19970722 Ver 1_Public Hearing Info_19980606

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RANDLEMAN RESERVOIR ISSUES
FOR HEARING OFFICERS' CONSIDERATION
(On the Issues, I need to know what our position is if we have one)
Discharge Requirements
1) Discharge remain in Richland Creek
a) Meet P limits of 0.5 mg/1 with goal of 0.2 mg/l?
b) Meet P limits of 0.18 mg0?
- monthly?
- quarterly?
- 90 day average?
- Maximum yearly P capped at 14,200 lb/yr?_
- No new or expanded discharges
ISSUES
Show differences in water quality from .18,.20, and.5 mg/1
What wq difference will the monthly, quarterly, or 90 day average make?
2) Discharge around Lake
- 0.5 mg/1?
1.0 mg/1?
ISSUES
Who opposes and how strong is opposition?
What limits would we give them?
Do we argue that people will be drinking effluent & it will enhance
protection?
Exactly how much benefit in WQ will be achieved?
3) Discharge into Segment #2
- 0.18 mg/1
- 0.5 mg/l?
- 1.0 mg/1
ISSUES
What limit would be applied? ?°'>
What reductions in violations expected? i
What increases in Chlorophyll a in segment 2? r
What additional costs to High Point? i
What will Environmental Health say? Should we meet with them?
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Other Discharge Issues
1) Designate waters as NSW?
- Nitrogen requirements about 3.4 mg/l at 26 MGD (734 #/day max.)
- Prepare detailed nutrient response model with appropriate public
involvement.
2) Dual power source or auxiliary generators?
ISSUES
Are we together on no NSW?
Do we have a position on auxiliary generators? - could ignore
Riparian Area Protection
1) Define streams affected
la) Use Soil Survey maps, Quad maps, and DWQ criteria? (they also
prepare a map)
1b) Use Soil Survey maps and Quad maps?
lc) Use only blue lines on the Quad maps?
1d) Set some acreage to exclude coverage?
ISSUES
Do we have a position on maps?
Do we need them to prepare a map with streams on it?
What about setting some acreage?
2) Define Geographical Area of Coverage
a) Entire watershed? (110,000 acres)
b) Lower watershed? (70,000 acres)
ISSUES
How do we feel about upper watershed?
Do models show any benefit to buffers in upper area?
3) Define Type and Size of Buffer
a) 50 foot riparian area of protection - as in Neuse
b) Use existing Water Supply requirements.
- 30 foot vegetated (can be cleared and vegetated)
- 100 foot vegetated for high density
ISSUES
. Are we willing to bend on the 50 feet?
2

4) Should local governments be required to record all riparian areas on new or
modified plats?
ISSUES
High Point's proposal dropped this requirement. Do we have a position?
( I probably need to talk to local government folks)
Density Controls
Option A -
- Allow existing density requirements in upper watershed to remain as adopted
in March. Do not make Kernersville, Forsyth Co., Greensboro, Guilford Co.,
High Point, and Jamestown do anything different than what is in place in the
upper watershed.
- Allow existing controls in lower watershed to remain as has been in place.
Allow High Point, Jamestown, and Archdale to adopt ordinances at least as
stringent as are in place in the upper watershed.
Option B
Require Kernersville, Forsyth County, Guilford County, High Point and
Greensboro to revise existing ws ordinances in upper watershed to apply the
more stringent density provisions.
Require Randolph County, Guilford County, Randleman, and Greensboro to
modify ordinances in lower watershed to meet Option B levels and require
High Point, Jamestown and Randleman to adopt ordinances in the lower part
of the watershed to match the Option B density provisions.
ADDITIONAL INFORMATION NEEDED
Comparisons of existing densities in upper part of watershed with Option B
proposal.
Comparison of High Point's proposal with Option B. What will difference
be in modelling?
I need 4 packages of info - all labelled.
I need summary of all comments by commenter and copies for them to see.
3
•
Table of Contents
Section 1 Draft Nutrient Reduction Strategy and Implementation Plan
February 1998
Section 2 Response to NC DWQ Comments
Draft Nutrient Reduction Strategy for Randleman Lake
March 19, 1998
Section 3 Analysis of Potential Water Quality for Toxic Organic Chemicals
in the Proposed Randleman Lake
TetraTech, Inc.
March 18, 1998
Section 4 Fecal Coliform Bacteria in the Proposed Randleman Lake
TetraTech, Inc.
March 18, 1998
Section 5 Support Documentation for Nutrient Load and Eutrophication
Model
TetraTech, Inc.
February 1998
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HAZEN AND SAWYER

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Section 1
Draft Nutrient Reduction Strategy
and Implementation Plan
February 1998
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Randleman Lake
[EXEM ILLS Nutrient Reduction Strategy
and

Implementation Plan

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; February 1998
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Piedmont Triad Regional Water Authority
Acknowledgments
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This Nutrient Reduction Strategy and Implementation Plan document was written and prepared
for the Piedmont Triad Regional Water Authority (PTRWA) by
Tetra Tech Inc.
4401 Building, Suite 200
79 Alexander Drive
P.O. Box 14409
RTP, NC 27709
in cooperation with Hazen & Sawyer, P.C. PTRWA also wishes to express appreciation for the
cooperation of its members, the Piedmont Triad Council of Governments, and other local
jurisdictions within the proposed Randleman Lake watershed, in compiling data and information
for this document and the strategy development process.
Watershed nutrient loading models and the lake water quality model used to develop and
evaluate the proposed Nutrient Reduction Strategy are summarized in separate documentation
prepared by Tetra Tech Inc.
0
0
Draft (February 1998) Table of Contents
TABLE OF CONTENTS
i
• Acknowledgments .............................................................
List of Figures ................................................................ v
List of Tables ................................................................ vi
EXECUTIVE SUMMARY ......................................................ES-1
1. BACKGROUND ........................................................ 1-1
1.1 PTRWA and the Proposed Randleman Lake ........................... 1-1
1.2 Need for a Nutrient Reduction Strategy ............................... 1-5
1.3 Purposes of Strategy and Implementation Plan ......................... 1-5
1.4 Components of the Strategy and Implementation Plan ................... 1-5
2. NUTRIENT REDUCTION GOALS AND OBJECTIVES ............................ 2-1
2.1 Applicable Water Quality Standards ................................. 2-1
2.2 General Discussion of Assimilative Capacity .......................... 2-1
2.3 Point and Nonpoint Source Reduction Goals .......................... 2-4
2.3.1 Analysis of Existing Conditions .............................. 2-5
2.3.2 Analysis of Future Conditions without Water Supply Protection .... 2-11

3. NUTRIENT REDUCTION STRATEGY ........................................ 3-1
3.1 Point Source Nutrient Control Program ............................... 3-1
3. 1.1 Enhanced Phosphorus Removal at High Point Eastside WWTP ...... 3-1
3.1.2 Potential for Control of Minor Dischargers ...................... 3-2
3.2 Nonpoint Source Control Program .................................. 3-3
3.2.1 Watershed Protection Ordinances ............................. 3-3
3.2.2 Structural Controls on Loads ................................ 3-12
3.2.3 Non-structural Control on Loads ............................. 3-18
3.2.4 Education and Outreach Programs ............................ 3-26
3.2.5 Monitoring and Enforcement ................................ 3-27
3.3 Summary and Evaluation of Proposed Nutrient Reduction Strategies ...... 3-27
3.3.1 Point Source Controls ..................................... 3-28
3.3.2 Estimated Effectiveness of Nonpoint Source Control Strategies ..... 3-28
3.3.3 Net Load Reductions under Nutrient Reduction Strategy .......... 3-30
3.3.4 Estimated Chlorophyll a Response with Nutrient Reduction Strategies
....................................................... 3-30
4. IMPLEMENTATION PLAN ................................................ 4-1
4.1 Schedule for Implementation ....................................... 4-1
• 4.2 Monitoring Program .............................................. 4-2
Piedmont Triad Regional Water Authority iii
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
4.2.1 Tracking Implementation Activities ........................... 4-2 •
4.2.2 Tracking Environmental Effectiveness ......................... 4-3
4.3 Data Management ............................................... 4-6
4.4 Evaluating and Updating Strategy and Implementation Plan .............. 4-6
5. REFERENCES ......................................................... 5-1
APPENDIX I. EXISTING POINT SOURCE NUTRIENT LOADS ........................ A-I-1
APPENDIX II. ESTIMATION OF FUTURE LAND USE CONDITIONS ................... A-II-1
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iv Piedmont Triad Regional Water Authority
Draft (February 1998) Table of Contents
LIST OF FIGURES
• Figure 1. Location of Proposed Randleman Lake ................................... 1-2
Figure 2. Randleman Lake Watershed ............................................ 1-3
Figure 3. Randleman Lake Watershed Model Segmentation .......................... 2-3
Figure 4. Randleman Lake Watershed High Growth Areas for Year 2025 ............... 2-13
Figure 5. Annual Phosphorus Loads from High Point Eastside WWTP ................. 3-2
Figure 6. Existing Water Supply Watersheds in the Randleman Lake Watershed .......... 3-5
Figure 7. Existing and Projected 2025+ Land Use for Randleman Lake Watershed ....... 3-11
Figure 8. Location of Regional Detention Ponds ................................... 3-13
Figure 9. Location of Proposed Constructed/Enhanced Wetlands ..................... 3-16
Figure 10. Future Nonpoint Source Phosphorus Loads with and without Watershed
Protection Ordinances ................................................. 3-28
Figure 11. Locations of Proposed Monitoring Sites ................................. 4-5
Figure A-1. Sewered Areas and Soils with Poor Suitability for Onsite Wastewater Disposal
in the Guilford County Portion of the Randleman Lake Watershed ............ A-II-4
is
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Piedmont Triad Regional Water Authority v
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
LIST OF TABLES
Table 1. Jurisdictional Composition of Proposed Randleman Lake Watershed (acres and i
percent of land surface) Including Municipal Extra-Territorial Jurisdictions ........ 1-4
Table 2. Nutrient Export Rate Estimates ......................................... 2-6
Table 3. Estimated Existing Land Use by Sub-Watershed (acres) ...................... 2-7
Table 4. Estimated Nutrient Loads by Lake Segment (kg/yr) for Existing Conditions with
WWTP at 10.5 MGD, 4 mg/l Total Phosphorus, and 20 mg/1 Total Nitrogen ....... 2-8
Table 5. Chlorophyll a Predictions for Existing Conditions .......................... 2-9
Table 6. Estimated Future Land Use by Sub-Watershed (acres), without new WS Ordinances
................................................................... 2-15
Table 7. Estimated Nutrient Loads by Lake Segment (kg/yr) for Future Conditions, without
Nutrient Reduction Strategy,
WWTP at 26 MGD, 1 mg/1 Total Phosphorus, and 6 mg/1 Total Nitrogen ......... 2-16
Table 8. Chlorophyll a Predictions for Future Conditions,
without Nutrient Reduction Strategy ...................................... 2-16
Table 9. Future High Point Eastside WWTP Nutrient Loads (kg/yr) ................... . 3-2
Table 10. Existing Watershed Overlay Districts for Randleman Lake Watershed.......... . 3-6
Table 11. Limits to Development Density in Water Supply Protection Ordinances ........ . 3-8
Table 12. Estimated Future Land Use by Sub-Watershed (acres) with Water Supply
Protection Ordinances ................................................. 3-10
Table 13. Estimated Reduction in Nonpoint Nutrient Loads by Lake Segment (kg/yr)
Achieved by New Water Supply Protection Ordinances for Future Land Use
Conditions .......................................................... 3-11
Table 14. Proposed Constructed / Enhanced Wetlands ............................. 3-15
Table 15. Stormwater Controls Required by Water Supply Protection Ordinances ........ 3-19
Table 16. Primary Resource Concerns Addressed by Agricultural Soil Erosion
Control Plans ........................................................ 3-20
Table 17. Estimated Reduction in Nonpoint Nutrient Loads by Lake Segment (kg/yr)
Achieved by Enhanced BMP Implementation on Crop Land for Future Land Use
Conditions .......................................................... 3-21
Table 18. Stream Buffer Requirements in Water Supply Protection Ordinances .......... 3-22
Table 19. Factors Determining Suitability for Septic Systems ........................ 3-25
i

Vi Piedmont Triad Regional Water Authority
Draft (February 1998) Table of Contents
Table 20. Estimated Nutrient Loads by Lake Segment (kg/yr) for Future Conditions,
• with Nutrient Reduction Strategy, WWTP at 0.2 mg/l Total Phosphorus and
6 mg/1Total Nitrogen .................................................. 3-29
Table 21. Chlorophyll a Predictions for Future Conditions with Nutrient Reduction
Strategy and WWTP at 26 MGD and 0.2 mg/1 Total Phosphorus ................ 3-31
Table 22. Schedule for Implementation of Management Actions ...................... 4-1
Table 23. Proposed Programmatic Indicators to Track Plan Implementation ............. 4-2
Table 24. Proposed Environmental Indicators to Track Plan Implementation ............. 4-3
Table A-1. Domestic Type Dischargers in Randleman Lake Watershed ................. 6-2
Table A-2. Transfer Matrix for Calculating Potential Future Guilford Co. Land Use Based
On 2025 Projections ................................................. A-II-5
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Piedmont Triad Regional Water Authority vii
Draft (February 1998)
• EXECUTIVE SUMMARY
Background and Purpose
•

Executive Summary
The Piedmont Triad Regional Water Authority (PTRWA) plans to build Randleman Lake as a
safe and dependable water supply for the North Carolina Piedmont Triad Region. The
impoundment, expected to satisfy water demands for the next 50 years, will have a surface area
of 3,230 acres (at normal pool) in Guilford and Randolph Counties and will fall within sub-basin
03-06-08 of the Upper Cape Fear River Basin. The Randleman Lake watershed (450 km';
110,930 acres) will include parts of nine local jurisdictions-Forsyth, Guilford, and Randolph
counties, and the cities of Archdale, Greensboro, High Point, Jamestown, Kernersville, and
Randleman.
Because of the proposed lake's location downstream of the region's most rapidly urbanizing area,
existing and future sources of pollution could threaten water quality of the lake. Although the
majority of the lake is projected to meet water quality standards, modeling studies indicate that
nutrients from existing and proposed wastewater discharges and nonpoint sources will cause an
overabundance of algae growth and pose difficulty in meeting the state's related chlorophyll a
standard in the upper reaches of the lake. The purpose of this Nutrient Reduction Strategy and
Implementation Plan is to establish a set of goals and a management plan of action to achieve and
maintain adequate water quality in the proposed reservoir.
Nutrient Reduction Goals and Objectives
The following water quality goals have been established based on North Carolina water quality
standards and U.S. Environmental Protection Agency recommendations:
1) Attain a lakewide areal average chlorophyll a concentration of less than 25 µg/l.
2) Meet an average chlorophyll a concentration of less than 15 µg/l at the water supply
intake.
3) Do not exceed 40 µg/1 chlorophyll a more than 5% of the growing season in any segment
of the lake.
Modeling studies indicate that goals 1 and 2 can be met under both existing and projected future
nutrient loading conditions without a nutrient reduction strategy. The third goal cannot be met in
some segments of the lake under existing and projected future nutrient loading conditions.
Nutrient reduction goals and objectives are therefore driven by the third water quality goal.
Nutrient loading capacity (i.e., the maximum amount of nutrient loading that can be assimilated
by a waterbody and still allow the waterbody to meet water quality standards) varies by lake
segment and flow conditions. The upper segment of the Deep River arm of Randleman Lake is
projected to be the most sensitive to nutrient loading. To meet the third water quality goal in this
Piedmont Triad Regional Water Authority ES-1
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
lake segment, total phosphorus loading would need to be reduced to 2,880 kg during a high flow
year, 1,800 kg during an average flow year, and only 600 kg during a low flow year based on
water quality modeling analysis. For the upper segment of the Muddy Creek arm of Randleman
Lake, the total phosphorus loading capacity is estimated to be 2,290 kg/yr under high flow
conditions, 1,700 kg/yr under average flow conditions, and 780 kg/yr under low flow conditions.
Existing phosphorus loading to the upper segment of the Deep River arm is estimated to be about
60,700 kg during a low flow year, 63,600 kg during an average flow year, and 66,150 kg during a
high flow year. Approximately 58,000 kg/yr of these estimated loads is attributed to the
discharge from the High Point Eastside Wastewater Treatment Plant (WWTP). To meet the
loading targets in the upper segment, therefore, total phosphorus loading would need to be
reduced from existing loading levels by 60,100 kg during a low flow year, 61,800 kg during an
average flow year, and 63,860 kg during a high flow year. For the Muddy Creek arm, existing
total phosphorus loading is estimated to be about 800 kg during a low flow year, 1,700 kg during
an average flow year, and 2,730 kg during a high flow year. To meet the loading targets in the
Muddy Creek arm, total phosphorus loading must be reduced from existing loading levels by 20
kg during a low flow year, 0 kg during an average flow year, and 440 kg during a high flow year.
These nutrient reduction goals are summarized in the table below.
Total Phosphorus Nutrient Loading Reductions Goals for the Randleman Lake
Watershed
Randleman Lake Segment TP Reduction TP Reduction TP Reduction
Goal for Goal for Goal for
Low Flow Year Average Flow High Flow Year
(kg) Year (kg) (kg)
Upper segment of Deep River 60,100 61,800 63,860
Lake arm
Upper segment of Muddy 20 0 440
Creek Lake arm
0
Full achievement of the nutrient reduction goals for the upper segment of the Deep River arm is
not feasible at this time because of technological, economic, and environmental constraints on
reducing phosphorus loading from the High Point Eastside WWTP. Under an assumption that
half of the phosphorus load at loading capacity is attributable to nonpoint sources, the WWTP
would need to achieve an effluent concentration of 0.020 mg/1 total phosphorus to meet the i
loading capacity during low flow conditions and 0.060 mg/1 during average flow conditions for
the current WWTP discharge of 10.5 MGD. For expected buildout capacity flow from the
WWTP of 26 MGD, concentrations would need to be reduced to 0.008 mg/1 during a low flow
year and 0.025 mg/1 during an average flow year to meet the loading capacity. Even if all of the
point source loading were removed, however, achieving the reduction goals for nonpoint sources
would prove to be a formidable challenge. The initial objectives of this Nutrient Reduction
Strategy have therefore been set to make substantial progress toward these goals, with the hope
ES-2 Piedmont Triad Regional Water Authority
Draft (February 1998) Executive Summary
of moving even closer or attaining the goals in the future as technology improves and constraints
• are removed or reduced. Achieving the reduction goals in Muddy Creek is feasible at present,
but significant increases in development density by 2025 could pose a substantial challenge to
meeting the goals in the future.
Initial Management Objectives for the Nutrient Reduction Strategy
Reduce point source loadings to the maximum extent feasible by connecting minor facilities
into the major municipal systems within the region and by reducing the High Point Eastside
WWTP total phosphorus concentration to the limits of technology and as environmentally and
economically feasible.
Implement nonpoint source nutrient loading controls in accordance with North Carolina Water
Supply Watershed Protection Rules and Regulations (NCGS 143-214.5 and 15A NCAC
213.0100 and .0200) to protect the water supply and prevent additional degradation of water
quality in the upper tributary segments of the reservoir.
Summary of Nutrient Reduction Strategy
The Nutrient Reduction Strategy is divided into two program areas, control of point source
nutrient loads and control of nonpoint source nutrient loads.
• Control of Point Source Nutrient Loads
An expansion and upgrade of the High Point Eastside WWTP is currently underway, and is
expected to be online by July 2001. Initial plans for the 26-MGD facility called for meeting
effluent concentrations of 1 mg/1 total phosphorus and 6 mg/l total nitrogen. Under this first
phase of the Nutrient Reduction Strategy, PTRWA will work with the City of High Point to
achieve the environmentally sound limits of technology for phosphorus removal. The initial goal
is to achieve an effluent concentration of 0.2 mg/1 total phosphorus. PTRWA will provide a
financial incentive to the City of High Point to ensure meeting the goal on a consistent basis.
Additionally, PTRWA has identified two minor wastewater discharges that will be connected to
municipal WWTPs. PTRWA will also work with local utilities and the Division of Water
Quality to pursue connection of other minor facilities to the larger municipal sewer systems.
Combined, these actions should result in a reduction of approximately 51,750 kg/yr total
phosphorus (TP) and 78,200 kg/yr total nitrogen (TN). This constitutes more than 80 percent of
the phosphorus reduction goals for low and average flow years (see summary table below).
0
Piedmont Triad Regional Water Authority ES-3
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
Total Phosphorus (TP) Reductions from First Phase Point Source Control Strategies
Proposed Action Achieved TP Percent of TP
Reduction (kg/yr) Reduction Goal
Meet 0.2 mg/l TP in effluent of 26 MGD 50,850 85% - low flow yr
High Point Eastside WWTP 82% - average flow yr
Connect two minor discharges to 910 < 1% - low flow yr
municipal sewer systems < 1 % - average flow yr
TOTAL 51,760 86% - low flow yr
84% - average flow yr
Control of Nonpoint Source Nutrient Loads
Whereas significant reductions in point source loading can be achieved through improvements in
phosphorus removal technologies, total nonpoint source nutrient loading is expected to increase
over existing levels--even with significant management practices implemented-because of
anticipated development within the watershed and conversion of forested land to residential and
commercial use. Without a nutrient reduction strategy, nonpoint source loading of total
phosphorus in the year 2025 would be expected to increase from existing conditions by
approximately 14,100 kg in a low flow year, 20,740 kg in an average flow year, and 32,040 kg in
a high flow year. Although implementing nonpoint source controls will help minimize loading
increases, such controls are not expected to reduce loadings below existing levels.
The Nutrient Reduction Strategy for nonpoint sources has five major components:
¦ Water supply protection ordinances
¦ Structural controls on loads (e.g., regional stormwater ponds, constructed wetlands)
¦ Nonstructural controls on loads (e.g., best management practices)
¦ Education and outreach programs
¦ Monitoring and enforcement
WATER SUPPLY PROTECTION ORDINANCES
Seven jurisdictions have area in the watershed that drains directly to the proposed Randleman
Lake and not to the upstream water supply watersheds (Oakdale, City Lake, and Oak Hollow
Lake) for which ordinances are already in place. PTRWA is working closely with each of these
jurisdictions to encourage adoption of ordinances that will help protect Randleman Lake.
Guilford County, Randolph County, Greensboro, and Randleman have all adopted water supply
protection ordinances for the proposed Randleman Lake that are more stringent than required
under the state's minimum guidelines for a WS-IV classification (the anticipated classification
for Randleman Lake). High Point, Jamestown, and Archdale will also adopt ordinances by law
assuming Randleman Lake is built and classified for water supply use. These ordinances will
exceed State standards for WS-IV and will include restrictions on housing density, limits on
ES-4 Piedmont Triad Regional Water Authority
•
•
leI
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Draft (February 1998) Executive Summary
impervious area for development, requirements regarding buffers along streams and stormwater
. controls for higher density development, and other means of reducing potential contamination of
the water supply.
Estimated reductions in nonpoint nutrient loads from future (2025) land use conditions are
summarized in the table below.
Estimated Reduction in Nonpoint Nutrient Loads to Randleman Lake for Future
Land Use Conditions (2025) Achieved by New Water Supply Protection Ordinances
Flow Condition Phosphorus Reduction (kg/yr) Nitrogen Reduction (kg/yr)
Low flow year 5,130 (22%) 36,330 (18%)
Average flow year 6,250(16%) 36,800 (10%)
High flow year 9,870(16%) 57,920 (10%)
For the upper Deep River segment of the lake, the water supply ordinances provide a total
phosphorus load reduction of approximately 1,900 kg/yr under an average flow condition-3
percent of the needed reductions from future loading conditions to meet water quality goals in
this segment.
STRUCTURAL CONTROLS ON LOADS
• Urban and development stormwater controls are assumed to be covered under the Water Supply
Watershed Protection Ordinances. However, the City of High Point plans to construct a fifth
regional stormwater pond in the watershed along the West Fork of the Deep River at the
outermost reach of Oak Hollow Lake. (The four existing structures have already been accounted
for in loading estimates.) The Skeet Club Road facility will provide an estimated loading
reduction of 1,280 kg/yr total phosphorus, and 6,600 kg/yr of total nitrogen under average flow
conditions. Net reduction in loading to Randleman Lake will be somewhat less, however,
because of assimilation of nutrients within Oak Hollow Lake and City Lake.
Six constructed/enhanced wetland areas will be created under the strategy. These sites will either
be constructed directly by PTRWA or by the State under the Wetland Restoration Enhancement
Program (WREP) if the Authority elects to pay into this wetland bank. These sites will be
developed directly by PTRWA or by the State using funds paid by PTRWA into the State
mitigation bank. The primary purpose of the new wetlands is for mitigation of impacts on
existing wetlands caused by impoundment of Randleman Lake, but the wetlands will also
provide a water quality benefit. The estimated load reductions under average flow conditions
from the projects combined are 890 kg/yr total phosphorus and 15,620 kg/yr total nitrogen.
CJ
Piedmont Triad Regional Water Authority ES-5
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
NONSTRUCTURAL CONTROLS ON LOADS
The Natural Resources Conservation Service (MRCS) estimates the current rate of best
management practice (BMP) implementation on active agricultural cropland within the
watershed to be near 90 percent. NRCS believes incentives are such that 100 percent
implementation in the future is a realistic goal because area in cropland is expected to decline
sharply in the watershed. However, only a small net reduction in nutrient load could be
expected-approximately 150 kg total phosphorus and 420 kg total nitrogen during a low flow
year; 330 kg total phosphorus and 900 kg total nitrogen during an average flow year; and 600 kg
total phosphorus and 1,600 kg total nitrogen during a high flow year.
There are only three animal operations within the watershed, and therefore an explicit estimate of
nutrient load reduction due to animal waste management has not been included. Waste
management plans are, however, important to ensure that these farms do not become a source of
excessive nutrient loads. Under 15A NCAC 2H .0200, concentrated animal operations of
significant size must have an animal waste management system to receive certification under a
general permit.
Other meaningful nonstructural management programs include stream buffer and setback
requirements (covered by Water Supply Protection Ordinances), site development standards,
erosion and sediment ordinances, and onsite wastewater disposal requirements. Although these
management programs are not credited with additional nutrient reduction, they nonetheless
represent proactive steps in preventing nutrient loads from exceeding those estimated from •
export coefficients.
PTRWA will work with its members and other jurisdictions in the watershed to conduct
education and outreach on the importance of public pollution prevention measures in helping to
achieve nutrient reduction goals in the Randleman Lake watershed. Existing means, such as
conservation district outreach programs and Greensboro's storm water management outreach
program, will be used as a foundation for this strategy component. PTRWA will provide
information to outreach programs summarizing the goals of the Nutrient Reduction Strategy and
the responsibilities of the public in helping achieve the goals.
MoNiTogm AND ENFORCEMENT
Monitoring and enforcement is an important part of the Nutrient Reduction Strategy. This
component helps ensure that the load reductions estimated for many of the proposed management
controls will actually be achieved. Enforcement Officers, such as those employed by the City of
High Point under its Development Ordinance, ensure that development activities comply with
ordinance provisions. Use of civil and criminal penalties provides an extra incentive for
compliance with requirements.
0:
ES-6 Piedmont Triad Regional Water Authority
Draft (February 1998) Executive Summary
Summary and Evaluation of Proposed Nutrient Reduction Strategy
• The projected effectiveness of all of the nonpoint source nutrient controls combined is displayed
in the table below.
•
•
Effectiveness of Nutrient Reduction Strategy in Minimizing Future
Noupoint Source Loads
Load Description Low Flow Year High Flow Year Average Flow
Year
TP (kg) TN (kg) TP (kg) TN (kg) TP (kg) TN (kg)
Estimated total existins 8,890 96,540 29,680 375,220 18,900 243,870
nonpoint source loads
Total future nonpoint source 22,990 203,470 61,720 589,150 39,640 386,190
loads without Nutrient
Reduction Strategy
Total tore nonpoint source 16,460 158,390 49,520 513,810 31,640 336,950
loads with Nutrient
Reduction Strategy
Net reduction for future 6,530 45,080 12,200 75,340 8,000 49,240
nonpoint source loads from
(28%)
(22%)
(20%)
(13%)
(20%)
(13%)
implementing Strategy
Net Load Reductions in Critical Lake Segments Under Nutrient Reduction Strategy
Combining the point and nonpoint loading estimates, the proposed Nutrient Reduction Strategy
is expected to result in a decrease from existing loading to the upper Deep River segment of
Randleman Lake of 48,340 kg total phosphorus (78 percent of the nutrient reduction goal) during
an average flow year. The corresponding reduction in total nitrogen loading for the upper Deep
River Segment is 58,180 kg. These figures, and loading figures for low and high flow years, are
summarized in the table below.
Net Nutrient Load Reductions in Critical Upper Deep River Segment of
Randleman Lake
[percent of reduction goal shown in brackets below reduction estimates]
Low Flow Year High Flow Year Average Flow Year
TP (kg) TN (kg) TP (kg) TN (kg) TP (kg) TN (kg)
49,370 64,760 47,090 50,390 48,340 58,180
[82%] [74%] [78%]
Piedmont Triad Regional Water Authority ES-7
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
Loading in the upper Muddy Creek segment is expected to increase, although the Nutrient
Reduction Strategy decreases loadings from what they would expected to be in the future without
the nonpoint source management strategies. 0 1
Net Nutrient Load Change in Upper Muddy Creek Segment of Randleman Lake
Scenario Description Low Flow Year High Flow Year Average Flow
Year
TP (kg) TN (kg) TP (kg) TN k

)
11

TP (kg)

TN (kg)
Existing load 800 12,000 2,730 47,210 1,690 29,580
Future load without Nutrient 4,150 35,460 10,220 90,160 6,400 58,220
Reduction Strategy
Future load with Nutrient 2,530 26,320 7,280 76,400 4,460 48,970
Reduction Strategy
Net increase from existing 1,730 14,320 4,550 29,190 2,770 19,390
load with Nutrient Reduction
(216%)
(119%)
(166%)
(62%)
(164%)
(66%)
Strategy
Net reduction from future 1,620 9,140 2,940 13,760 1,940 9,250
load with Nutrient Reduction
(39%)
(26%)
(29%)
(15%)
(30%)
(16%)
Strategy
Estimated Chlorophyll a Response with Nutrient Reduction Strategy
Substantial reductions in nutrient loading can be achieved through the first phase of the Nutrient
Reduction Strategy. Ultimate loading levels necessary to meet all water quality goals, however,
cannot yet be achieved because of technological constraints on WWTP nutrient removal.
Although chlorophyll a concentration goals are expected to be achieved for the lakewide average
and at the water supply intake, concentrations in the upper segments of the lake tributary arms are
still expected to exceed the 40 µg/l criterion more than 5 percent of the days during the algae
growing season. Chlorophyll a predictions under estimated loading conditions that reflect the
Nutrient Reduction Strategy are presented in the table on the next page.
Although the percent reductions in nutrient loading to the upper Deep River arm are relatively
high (e.g., 74-82 percent of goal), the response in chlorophyll a concentration is not as great
because this lake segment-dominated by effluent flow-responds more to the concentration of
the effluent than to the total loading. Progress toward reaching the goal of exceeding 40 µg/l less
than 5 percent of the time will only be achieved only when WWTP phosphorus removal
technology is improved and an effluent concentration of 0.008-0.025 mg/1 is achievable for the
High Point Eastside WWTP.
0
0
ES-8 Piedmont Triad Regional Water Authority [
Draft (February 1998) Executive Summary
l?
U
•
Randleman Lake Chlorophyll a Predictions for Future Conditions
with Nutrient Reduction Strategy
[gray-shaded rows provide comparative information for upper segments]
Lake Segment Low Flow Year High Flow Year Average Flow
Year
Chi a Percent Chi a Percent Chi a Percent
(µg/1) of time (µg11) of time (µg/1) of time
> 40 µg/1 > 40 µg11 > 40 µg/1
Lakewide average 20 NA 19 NA 19 NA
Water supply intake 12 1% 12 1% 12 1.0%
segment
Upper Deep River arm- 117 94% 8_3 84% 95 89%
e, is ' nutrient loading
conditions
Upper Deep River arm- 95 89%0 71 76% 80 83%a
future without , Nutrient
Reduction Strategy
Upper Deep River arm- 81 83% 61 67% 67 73%
future with Nutrient
Reduction Strategy
Upper Muddy Creek 19 5% 20 7%0 17 5%
arm- Lxisti= nutrient
loading conditions
Upper Muddy Creek 28 18% 28 18% 28 T 8%0
arm- future without
Nutrient Reduction
Strategy
Upper Muddy Creek arm- 26 14% 26 16% 26 14%
future with Nutrient
Reduction Strategy
Piedmont Triad Regional Water Authority ES-9
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (Februrny 1998)
Implementation Plan Summary
PTRWA will work with its members to implement the Strategy, monitor progress and `
effectiveness, and adapt the Strategy-based management actions as needed to reach interim and
long-term reduction goals.
Schedule
Management plan administration will be set up within 6 months of plan approval by the
Environmental Management Commission (EMC), and protocols and means for data collection,
information management, and assessment will be established within 12-18 months of EMC plan
approval.
Reduction of the High Point Eastside WWTP effluent TP concentration to 0.2 mg/l is scheduled
for July, 2001. Completion of the six wetlands projects is expected before filling of the
reservoir. Many of the watershed protection ordinances are already in place, and the remaining
jurisdictions will act quickly following reclassification of the waters for water supply. Actions
such as education and outreach, and ordinance enforcement will be conducted on an ongoing
basis.
PTRWA plans to reevaluate the Nutrient Reduction Strategy and Implementation Plan within
3-5 years of filling the reservoir, and every 5 years thereafter, coordinated with the Division of
Water Quality (DWQ)'s 5-year management cycle for the Cape Fear River Basin. An annual
progress report will be prepared for the Authority's Board and copied to DWQ within the first
3-6 months of the end of each calendar year.
Monitoring Program
The PTRWA monitoring program will track both programmatic and environmental indicators to
evaluate performance. Monitoring programmatic indicators of plan implementation will help to
ensure that proposed actions are completed, and will provide the Authority with information that
is key to analyzing the effectiveness of management actions. Proposed programmatic indicators
include the following
¦ Milestone dates for Plan Administration setup
¦ Date High Point Eastside enhanced treatment process comes on line
¦ Dates projects are completed (constructed wetlands, regional stormwater ponds)
¦ Date by which all local ordinances for water supply watershed protection are in place
¦ Dates of revisions to watershed protection ordinances by individual jurisdictions
¦ Dates environmental monitoring is performed
¦ Annual progress reports
¦ Dates of strategy and plan reevaluation amendment
i
ES-10 Piedmont Triad Regional Water Authority
Draft (February 1998) Executive Summary
Monitoring environmental impacts of plan implementation will allow PTRWA to gauge the
. overall effectiveness of the Nutrient Reduction Strategy and Implementation Plan.
Environmental indicators to be tracked include the following:
¦ Annual point source TP and TN loads
¦ Annual nonpoint source TP and TN loads
¦ Tributary water quality (TP, orthophosphate, total inorganic nitrogen, total organic
nitrogen)
¦ Lake water quality (same as tributary plus chlorophyll a, temperature, pH. Secchi
depth, and dissolved oxygen)
¦ Downstream Deep River water quality (same as upstream tributary parameters)
Baseline monitoring will be conducted prior to impoundment of the reservoir, and a full
monitoring program will begin after reservoir impoundment.
Data Management
PTRWA will develop and maintain computerized databases to track all programmatic and
environmental indicator results. A metadata file on all data coverages will be maintained.
PTRWA members will be advised regarding formats and protocols for transferring data and will
be responsible for adhering to quality assurance/quality control (QA/QC) and other protocols.
• Evaluating and Updating Strategy and Implementation Plan
PTRWA will conduct annual evaluations will be conducted by to determine progress made in
implementing the plan and achieving strategy goals. An annual progress report will be prepared
for the Authority's Board, and copied to DWQ within 3-6 months of the end of each calendar
year. The report will include estimates of point and nonpoint source loadings for the previous
year, as well as summaries of tributary and inlake water quality conditions. In each succeeding
year, the reports will include comparisons to loading rates and water quality conditions from
previous years' monitoring.
The PTRWA Board will be responsible for periodically updating the Nutrient Reduction Strategy
and Implementation Plan. The first update is scheduled for 3-5 years from the date of
impoundment of Randleman Lake. PTRWA anticipates that the new reservoir will take at least
2-3 years to stabilize with regard to water quality, based on reviewing study results from other
large impoundments in the Piedmont area. Therefore, the Authority will need to be careful not to
place too much emphasis on the inlake water quality monitoring data during those first 2-3 years
when evaluating the effectiveness of the initial plan. A decision on a more specific due date for
the plan update will not be made until after the first 2-3 years of data have been analyzed and
evaluated.
L?
Piedmont Triad Regional Water Authority ES-11
Draft (February 1998) Section 1 - Background
• 1. BACKGROUND
1.1 PTRWA and the Proposed Randleman Lake
This Nutrient Reduction Strategy and Implementation Plan is being developed by the Piedmont
Triad Regional Water Authority (PTRWA), in cooperation with the North Carolina
Environmental Management Commission (EMC) and the NCDENR Division of Water Quality
(DWQ). PTRWA is comprised of the governments of Randolph County and the municipalities
of Greensboro, High Point, Jamestown, Archdale, and Randleman. Archdale and Randleman are
located in Randolph County, while the other three municipalities are located in adjacent Guilford
County. PTRWA was formed in 1986 for the purpose of identifying, evaluating, and developing
long-term water supply alternatives for member governments.
PTRWA plans to develop a safe and dependable water supply for North Carolina Piedmont Triad
region that will satisfy estimated water demands for a planning period of approximately 50 years.
The Piedmont Triad Region is one of the faster growing areas in North Carolina, adding an
average 14,900 people and 14,100 jobs per year over the last decade (personal communication,
State Demographer, NC Office of State Planning to Andrea Spangler, PTRWA, 1/5/98).
Projections show the regions adding 273,400 people over the next 25 years. Based upon
expected regional growth in water demand, water shortages are predicted to occur shortly after
the turn of the century. While water conservation may reduce the rate of demand increase,
• continued regional growth is expected to lead to more water consumption and more severe
shortages in the future. PTRWA seeks to establish a water supply to provide an additional safe
yield of approximately 48 MGD to meet its projected needs through the year 2050. An adequate
water supply is necessary to support continued growth and economic vitality of the region.
To meet the growing demand for water, PTRWA has proposed building Randleman Lake. This
public investment of 123 million dollars would augment the region's water supply with an
allocation of 48 million gallons per day to meet projected demands. The proposed Randleman
Lake will be formed as an impoundment of the Deep River just north of Randleman, in Randolph
Co., NC (Figure 1). The proposed impoundment will have a surface area of 3,230 acres (at
normal pool) in Randolph and Guilford Counties, and will fall within the state's sub-basin 03-06-
08 of the Upper Cape Fear River Basin. The normal water surface elevation of the reservoir
would be 682 feet above mean sea level (msl), with a minimum water surface elevation of 635
msl. At the normal surface elevation the reservoir would have a storage volume of 18.3 billion
gallons, and an estimated safe yield of 54 million gallons per day (MGD) (Black & Veatch,
1990). The reservoir will contain two major arms, one formed along the Deep River and the
other formed along Muddy Creek.
Total watershed area draining to Randleman Lake will be 427 km' (105,294 acres) exclusive of
lake surface, lying in Randolph, Guilford, and Forsyth Counties (Figure 2). Three water supply
watersheds are located upstream of Randleman Lake: Oakdale, City Lake (High Point Lake), and
is
Piedmont Triad Regional Water Authority 1-1
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)

LEGEND
Proposed Randleman Lake
Randleman Lake Watershed
County Boundaries
Location of Proposed
Randleman Lake
5 0 5 10 15 20 Mles
Figure 1. Location of Proposed Randleman Lake
Oak Hollow Lake Watersheds, all classified by the state as WS-IV. The Oakdale Watershed,
located above the Oakdale mill run-of-the-river dam on the Deep River below High Point Lake,
was the former water supply for the City of Jamestown, but is no longer used for this purpose.
High Point Lake (City Lake) is an impoundment on the Deep River completed in 1928 to serve
as a water supply for the City of High Point. This lake has a surface area of 275 acres, a storage
volume of 1.2 billion gallons, and a total drainage area of 61.4 square miles. Oak Hollow Lake,
on the West Fork of the Deep River above High Point Lake, was completed in 1971 to
supplement High Point's water supply. Oak Hollow Lake has a surface area of approximately
700 acres, a storage volume of 3.3 billion gallons, and a drainage area of 31.2 square miles. Both
Oak Hollow and High Point Lakes have sufficiently large storage capacity and retention time to
exert an important influence on the flow of water and movement of nutrients from the watershed
to Randleman Lake.
The Randleman Lake watershed will include parts of nine local jurisdictions with zoning and
planning authority, each of which will be responsible for implementing local water supply
protection ordinances. Areas of the watershed under direct zoning control of each jurisdiction
(including municipal extra-territorial jurisdictions) are shown in Table 1, which includes the area
which will be flooded by the proposed lake. This table represents best estimates of existing
(1997) zoning authority, although High Point's zoning map was not available electronically.
1-2 Piedmont Triad Regional Water Authority

I?

Draft (February 1998) Section 1 - Background

is
•
Legend
Randleman Lake Watershed
Lakes
Major Streams
- /County Lines
t n Cities
6 - VI. -
.f r r
1 0 1 2 3 4 5 Niles
Figure 2. Randleman Lake Watershed
Piedmont Triad Regional Water Authority
1-3
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
Table 1. Jurisdictional Composition of Proposed
Randleman Lake Watershed (acres and percent of land surface)
Including Municipal Extra-Territorial Jurisdictions
Jurisdiction Randleman City (High Point) Oak Hollow Randleman Lake
Lake Direct Lake Watershed Lake Watershed Total Watershed
Drainage
Guilford Co. 24,202 4,570 8,551 37,323
(36.0%) (24.0%) (41.9%) (35.0%)
Randolph Co. 22,942 0 0 22,942
(34.1 %) (0%) (0%) (21.5%)
Forsyth Co. 0 0 2,310 2,310
(0%) (0%) (11.3 %) (2.2%)
Archdale 4,719 0 0 4,719
(7.0%) (0%) (0%) (4.4%)
Greensboro 1,769 5,141 4 6,914
(2.6%) (27.0%) (0.0%) (6.5%)
High Point 11,410 8,638 7,995 28.043
(17.0%) (45.3%) (39.1 %) (26.3%)
Jamestown 1,797 715 0 2,512
(2.7%) (3.8%) (0%) (2.4%)
Kernersville 0 0 1,564 1,564
(0%) (0%) (7.7%) (1.5%)
Randleman 372 0 0 372
(0.6%) (0%) (0%) (0.-)%)
Total Land Area 67,211 19,064 20,424 106,700
(63.0 %) (17.9 %) (19.1 %) (100 %)
Water Surface 3,123 365 742 4,230
Total Area 70,334 19,429 21,166 110, 930
•
0
1-4 Piedmont Triad Regional Water Authority
Draft (February 1998) Section 1 - Background
Within Oak Hollow and City Lake watersheds, there has been a shift in jurisdiction from the
. county to Greensboro and High Point since the CDM (1989) study. Total watershed area
calculated for this plan is 110,930 acres.
1.2 Need for a Nutrient Reduction Strategy
Randleman Lake is proposed to be built downstream of the most rapidly urbanizing area in the
region. Although the lower section of the lake proposed for the water supply intake is projected
to meet water quality standards, existing development and projected growth could generate
pollution that threatens the quality of the upper sections of the lake. Projections of nutrients
discharged from wastewater treatment plants and running off city streets, subdivision lawns,
gardens, septic fields, and farmland are a particular concern. Water quality modeling studies
indicate that nutrients from existing conditions in the region will cause overabundance of algae
growth and pose difficulty in meeting the state's related chlorophyll a standard in the upper
reaches of the lake. The water quality conditions are further threatened by projections of added
growth.
1.3 Purposes of Strategy and Implementation Plan
The purposes of this Nutrient Reduction Strategy and implementation plan are to:
¦ determine the level of nutrient reduction needed to assure that associated water
quality standards are met throughout the lake
¦ identify the most cost-effective ways of reducing nutrient loading to target levels
¦ establish accountability in meeting nutrient reduction targets
¦ provide a gauge to measure success in meeting water quality standards and to adapt
management to take advantage of new information and technologies.
1.4 Components of the Strategy and Implementation Plan
The proposed Randleman Lake Nutrient Reduction Strategy and Implementation Plan, as
detailed herein, contains the following three components:
¦ Nutrient Reduction Goals and Objectives
¦ Nutrient Reduction Strategy
¦ Implementation Plan
The Goals and Objectives component (Section 2) uses modeling analysis and North Carolina
water quality standards and U.S. EPA guidance as a basis for establishing nutrient loading
targets, and documents predicted water quality conditions if the reservoir was built now,
predictions for future conditions without water supply protection, and needed nutrient loading
reductions. The Nutrient Reduction Strategy component (Section 3) describes proposed
approaches to reducing nutrient loading from point and nonpoint sources and provides an
estimate of expected results of the strategy. Finally, the Implementation Plan component
(Section 4) outlines how the reductions will be accomplished and sustained into the future.
Piedmont Triad Regional Water Authority 1-5
Draft (February 1998) Section 2 - Nutrient Reduction Goals and Objectives
is 2. NUTRIENT REDUCTION GOALS AND OBJECTIVES
2.1 Applicable Water Quality Standards
The proposed Randleman Lake is expected to be classified as a Class WS-IV Water. Under state
regulations, waters of this class are protected as water supplies which are generally in moderately
to highly developed watersheds (15A NCAC 2B.0211 (f)(2)). Because of the presence of the
High Point Eastside Wastewater Treatment Plant at the upper end of the Deep River arm, the
proposed reservoir is expected to experience excess loading of the nutrients phosphorus and
nitrogen, which can lead to undesirable growth of nuisance algae and unaesthetic conditions.
The State of North Carolina does not specify numeric water quality standards for nutrients;
however, a water quality standard applicable to all fresh surface waters is established for
chlorophyll a, a measure of algal concentration (15A NCAC 2B.0211 (b)(3)(A)):
Chlorophyll a (corrected): not greater than 40 µg/l for lakes, reservoirs, and other
slow-moving waters not designated as trout waters ... ; the Commission or its
designee may prohibit or limit any discharge of waste into surface waters if, in the
opinion of the Director, the surface waters experience or the discharge would
result in growths of microscopic or macroscopic vegetation such that the
standards established pursuant to this Rule would be violated or the intended best
usage of the waters would be impaired;
is
EPA Region 4 has suggested more stringent limits for chlorophyll a in southeastern
impoundments': "It was determined that at a mean growing season limit of s 15 µg/l of
chlorophyll a, that very few problems would be incurred with respect to water supply. For other
uses, a mean growing season chlorophyll a of < 25 µg/1 is recommended to maintain a minimal
aesthetic environment for viewing pleasure, safe swimming, and good fishing and boating."
Based on these recommendations, North Carolina has considered more stringent goals for water
supply waters, including an average ambient chlorophyll a concentration of 25 µg/l coupled with
a not-to-be-exceeded' action level of 40 µg/l, although adoption of these goals as standards is not
currently being pursued by DWQ.2
2.2 General Discussion of Assimilative Capacity
The aim of the Nutrient Reduction Strategy is to attain the relevant water quality standard of 40
µg/l chlorophyll a within Randleman Lake. The Nutrient Reduction Strategy also addresses
' Raschke, R. 1993. Guidelines for Assessing and Predicting Eutrophication Status of Small Southeastern Piedmont
Impoundments. EPA Region IV, Environmental Services Division, Ecological Support Branch, Athens, GA.
2 Diane Reid, North Carolina Division of Water Quality, personal communications Feb. 8, 1996 and Nov. 21, 1997.
Piedmont Triad Regional Water Authority 2-1
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
attainment of the EPA recommendations of a lake-wide average concentration of s 25 µg/1
chlorophyll a, and an average concentration of s 15 µg/l within the lake segment adjacent to the 40
water supply intake. Attaining a chlorophyll a concentration goal within an impoundment
generally requires controlling the loading of nutrients into the impoundment.
Determining appropriate nutrient reduction goals requires an assessment of the assimilative
capacity of the proposed reservoir (also known as loading capacity). That is, what magnitudes of
nutrient loads are consistent with achieving the chlorophyll a standard? Federal regulations
under the Clean Water Act (40 CFR 130.2(f)) define the loading capacity as "the greatest amount
of loading that a water can receive without violating water quality standards." It is important to
realize that the assimilative capacity for nutrients is not a single, fixed loading amount. First,
algal response within a lake varies from year to year in response to variable rates of inflow of
water and flushing of reservoir segments. The water quality response within a reservoir also
depends on where the loads occur: a nutrient load concentrated in one arm of the reservoir may
produce a violation of the chlorophyll a water quality standard in that arm, whereas the same
load distributed throughout the reservoir might not result in any excursion of the standard.
Finally, loading capacity for one algal nutrient depends on the availability of other nutrients
required for algal growth. Assimilative capacity thus varies in both time and space, and cannot
be specified as a single fixed rate of loading. Instead, assimilative capacity for a reservoir must
be specified conditional on assumptions about hydrology and locations of nutrient sources.
For development of the Nutrient Reduction Strategy, the assimilative capacity of the proposed
Randleman Lake was evaluated through the application of water quality models of the lake and •
watershed. The reader is referred to the separate modeling report (Tetra Tech, 1997) for a
complete description of the model development and implementation. For the purposes of
modeling and analysis, Randleman Lake has been divided into a number of segments, as
described in the separate modeling report. These segments and their associated watersheds are
shown in Figure 3. Note that sub-watershed Deep River 3 is divided into two lake segments for
water quality modeling. The proposed water intake is located in segment Deep River 3B.
The Tetra Tech Randleman Lake models were used to assess expected water quality if the
reservoir were constructed now, and future water quality which would be expected from
increased development of the watershed and increases in wastewater flow without a nutrient
reduction strategy. These results provide the baseline against which to evaluate assimilative
capacity (both current and future) and needed levels of nutrient reduction.
The lake water quality model allows prediction of expected chlorophyll a concentrations. These
concentrations are most strongly driven by phosphorus concentrations. Assimilative capacity
for phosphorus was then assessed in terms of the expected probability of meeting (1) the state
standard of 40 µg/l chlorophyll a, (2) the EPA recommendation of attaining a lake-wide areal
average concentration of less than 25 4g/1, and (3) the EPA recommendation of meeting an
average concentration of less than 15 µg/1 at the water intake segment. It is not reasonable to
propose that the 40 4g/1 standard be predicted to be met 100% of the time. First, occasional algal
2-2 Piedmont Triad Regional Water Authority
Draft (February 1998) Section 2 - Nutrient Reduction Goals and Objectives
•
•
Figure 3. Randleman Lake Watershed Model Segmentation
to
Piedmont Triad Regional Water Authority 2-3
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998) _
blooms occur in most Piedmont reservoirs even when the average algal concentration and
nutrient load is moderate. Second, the predictive modeling tool generally yields a good estimate
of mean chlorophyll a, but can provide only a rough approximation of the expected frequency of
nuisance algal blooms. It is therefore proposed that model-predicted frequency of less than 5
percent of days during an annual growing season (May to October) with chlorophyll a
concentration greater than 40 µg/l is a reasonable indicator and appropriate target for assessing
assimilative capacity.
In general, the second and third goals are expected to be attained fairly easily, as documented
below in Section 2.3.1. Within the lower segments of the reservoir there is available assimilative
capacity for nutrients, and low chlorophyll a concentrations are expected. Potential excursions
of the 40 4g/1 standard are, however, likely in the upstream segments of the reservoir (upstream
segments of Deep River arm and Muddy Creek arm). Both of these upstream segments have a
small volume and receive substantial nonpoint source runoff from the urbanized High Point-
Archdale area. In addition, the Deep River arm receives effluent from the High Point Eastside
WWTP. Indeed, the model predicts that the goal of less than 5 percent of days with chlorophyll
a concentrations greater than 40 µg/l would not be met in the uppermost part of the Deep River
arm due to nutrient loads from the WWTP alone and with no watershed contribution of load,
even with the WWTP attaining a very high degree of nutrient removal. The hydrologic
characteristics of the uppermost section of the Muddy Creek arm will also make it very difficult
to achieve this goal within that area. Assimilative capacity is thus expected to be exceeded in the
upstream segments of the Deep River an Muddy Creek arms regardless of the controls placed on
watershed loading of nutrients. The strategy proposed for these segments is thus to reduce
nutrient loads as far as possible in order to minimize the occurrence of unacceptable conditions.
As noted above, assimilative capacity cannot be given as a single loading rate, due to interactions
among parameters. The model predicts chlorophyll a response to both phosphorus and nitrogen
loading, and the effects of phosphorus load depend on the level of nitrogen load. Algal response
is also sensitive to the partitioning between organic and inorganic fractions of the influent load.
Assimilative capacity will therefore be presented in context of specific analysis scenarios.
2.3 Point and Nonpoint Source Reduction Goals
Because loading capacity for nitrogen and phosphorus cannot be given by a single number,
reservoir chlorophyll a response must be analyzed for a variety of different conditions and
evaluated for attainment of water quality standards. Where water quality standards are not met,
additional reductions can be determined suitable to the specific conditions analyzed. In general,
water quality standards ought to be met both at the time the reservoir is built (existing land use)
and in the future as development occurs and land use changes (future land use). Further,
attainment of standards needs to be addressed across the expected range of meteorological
conditions.
E
2-4 Piedmont Triad Regional Water Authority
Draft (February 1998) Section 2 - Nutrient Reduction Goals and Objectives
40 2.3.1 Analysis of Existing Conditions
The first point of reference for analysis of assimilative capacity is predicted water quality given
that the reservoir was built now, with existing land uses and point sources at current operating
levels. Note that the Nutrient Reduction Strategy proposed for the High Point Eastside
Wastewater Treatment Plant (WWTP) is expected to result in a significant reduction in these
loads prior to actual filling of the impoundment. The existing condition analysis provides a
baseline for evaluating nutrient reductions.
Existing Point Source Loads
Existing point source loads are described in detail in Appendix I. The vast majority of point
source loading to the proposed Randleman Lake will come from the High Point Eastside WWTP.
Based on facility self-monitoring data (May 1996-May 1997), the High Point Eastside WWTP
discharges an annual phosphorus load of 58,070 kg/yr (128,021 lbs/yr), and a total nitrogen load
of 290,350 kg/yr (640,105 lbs/yr).
In addition, there are 11 active "domestic type" permitted discharges of treated wastewater within
the Randleman Lake Watershed (letter from W. C. Basinger, NCDWQ Winston-Salem, to
Andrea Spangler, PTRWA, 19 November 1997). These discharges-made up of schools, mobile
home parks, and a correctional center-do not have self-monitoring data on total phosphorus (TP)
and total nitrogen (TN) loading. Upper bound estimates of total load from these facilities, based
on a total operational permitted flow of 0.29 MGD and assuming typical TP and TN
concentrations of 5 mg/l and 20 mg/l respectively, are 2,005 kg/yr (4,420 lbs/yr) TP and 8,020
kg/yr (17,680 lbs/yr) TN. Actual load is likely to be considerably less, as actual flow is expected
to be less than permitted flow.
Existing Nonpoint Source Loads
Nonpoint loading of nutrients reflects physical features of the land surface (e.g., geology, soils,
slopes, and vegetative cover) and the uses of the land (e.g., agricultural, commercial, industrial,
residential, and open space), including management practices that influence the amount and
quality of water running off the land. Nonpoint source loads are estimated using a modified
export coefficient approach, as described in the accompanying modeling document. Table 2
provides nutrient export rate estimates (export coefficients) for each land use type as a long-term
average rate, as documented for the Randleman Lake watershed in CDM (1989) and Black &
Veatch (1991). Different rates apply to generalized hydrologic soil groups Band C; however,
soils within the watershed are primarily Class C soils.
There is not a detailed map of existing land uses in the Randleman Lake watershed available.
Instead, land use must be determined from a variety of sources, including Census, zoning, and
land cover information. To represent "existing" conditions we relied on the analysis presented in
Piedmont Triad Regional Water Authority 2-5
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998) r
Black & Veatch (1991), which summarizes land uses as of ca. 1989, modified to account for
Randleman Lake being constructed. The distribution of land uses by sub-watershed is shown in
Table 3. Note that large-lot rural residences are not accounted for separately, but are subsumed
into the forest, pasture, and agricultural land uses. (The total area shown in Table 3 is slightly
less than the revised area determined from the project GIS and shown in other tables because
Black & Veatch data were developed using other means.)
Table 2. Nutrient Export Rate Estimates
Land Use Phosphorus (lb/acre-yr) Nitrogen (lb/acre-yr)
Soil Group B Soil Group C Soil Group B Soil Group C
Forest 0.08 0.08 0.6 0.6
Open Space 0.08 0.08 0.6 0.6
Pasture 0.5 0.5 2.6 2.6
Cropland with BMPs 0.8 0.9 10.3 10.5
Cropland, High Till 4.7 5.6 15.9 17.3
Large Lot SF Residential (2
to 5-acre lots) 0.4 0.4 4.4 4.1
Low Density SF Residential
(1 to 2-acre lots) 0.8 0.9 6.7 6.6
Low-Medium Density SF
Residential (0.5 to 1-acre
lots) 1.0 1.0 8.0 8.0
Medium Density SF
Residential (0.25 to 0.5 acre
lots) 1.1 1.1 8.8 8.8
Institutional 1.1 1.1 8.8 8.8
Townhouse/ Apartment 1.6 1.7 12.9 13.1
Commercial/ Office 1.6 1.6 13.2 13.2
Heavy Industry 1.3 1.3 11.3 11.2

r
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2-6 Piedmont Triad Regional Water Authority
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Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
The predicted algal response within the proposed Randleman Lake is sensitive to loading of both
phosphorus and nitrogen. Table 4 presents estimates of the total nutrient loads to the proposed w
reservoir from both point and nonpoint sources (including minor point sources) if the reservoir
was built under existing conditions. The loads are shown by lake segment. Note that these
estimates include nutrient reductions achieved by the recent construction of four regional
stormwater detention ponds in the Oak Hollow and City Lake watersheds (see Section 3.2.2).
Table 4. Estimated Nutrient Loads by Lake Segment (kg/yr) for Existing Conditions
with WWTP at 10.5 MGD, 4 mg/l Total Phosphorus, and 20 mg/l Total Nitrogen
Segment Low Flow Year High Flow Year Average Flow Year
P N P N P N
Oak Hollow 1,240 15,980 4,690 65,150 3,030 43,620
City Lake 1,790 16,770 7,320 72,400 4,020 42,230
Deep River 1 (NPS and
minor PS) 2,610 24,130 8,080 87,670 5,570 60,260
Deep River 1 (WWTP) 58,070 290,350 58,070 290,350 58,070 290,350
Deep River 2 1,130 14,830 3,290 58,170 2,260 39,190
Deep River 3A 910 6,420 1,670 18,030 1,250 12,340
Deep River 3B 60 1,060 280 4,410 160 2,760
Muddy Creek 1 800 12,000 2,730 47,210 1,690 29,580
Muddy Creek 2 170 2,350 780 9,940 440 6,150
Near Dam 180 2,990 850 12,250 480 7,750
TOTAL 66,960 386,890 87,750 665,580 76,970 534,220
Total Nonpoint Source 8,890 96,540 29,680 375,220 18,900 243,870
Loading generated by land uses in the proposed Randleman Lake watershed will vary from
average load rates in a given year because of differences in rainfall patterns and runoff.
Accordingly, loading rates are modified to reflect load generation corresponding to meteorology
experienced in an actual year (see modeling report).
Chlorophyll a Predictions for Existing Conditions
•
Predictions for growing-season average chlorophyll a concentrations and frequency of nuisance
conditions (chlorophyll a greater than 40 µg/1) are shown in Table 5, based on existing watershed
I
2_8 Piedmont Triad Regional Water Authority
Draft (February 1998) Section 2 - Nutrient Reduction Goals and Objectives
and point source conditions described above. Results are given for extreme low flow, high flow,
• and average flow years, representing the range of potential responses. The predictions for Oak
Hollow and City Lakes reflect the nutrient reduction achieved by the recently-constructed
regional stormwater detention ponds, which are estimated to reduce average chlorophyll a
concentrations in City Lake by approximately 2 µg/l from conditions observed prior to 1997.
•
Table 5. Chlorophyll a Predictions for Existing Conditions
Lake Segment Low Flow Year High Flow Year Average Flow Year
(see Figure 3)
Chl a
(µg/1)
Nuisance
Frequency
Chl a
(µg/1)
Nuisance
Frequency
Chi a
(µg/1)
Nuisance
Frequency
Oak Hollow 11 0.6% 14 1.5% 13 1.2%
City Lake 19 6.0% 21 7.7% 20 7.0%
Deep River 1 117 94.4% 83 84.2% 95 89.0%
Deep River 2 39 36.8% 33 25.9% 35 30.0%
Deep River 3A 19 5.7% 20 6.2% 20 6.2%
Deep River 3B 13 1.1% 14 1.6% 14 1.6%
Muddy Crk 1 19 5.4% 20 6.5% 17 5.1%
Muddy Crk 2 11 0.6% 15 2.0% 14 1.4%
Near Dam 8 0.1% 12 1.0% 11 0.5%
Lake Randleman
Average 22 22 22
Predicted chlorophyll a concentrations for existing conditions, with no reduction in point or
nonpoint source loads of nutrients, meet two of the three management objectives: the predicted
lakewide average concentration is less than 25 µg/l, and the average concentration in the water
supply intake segment (Deep River 313) is less than 15 µg/l under all flow conditions. All
segments of Randleman Lake are expected to experience occasional algal blooms, although the
frequency of days with concentrations of chlorophyll a greater than 40 µg/l (nuisance conditions)
is expected to be less than 5 percent in the lower portions of the lake. Severe nuisance conditions
are, however, predicted for the lake segments immediately downstream of the High Point
WWTP. Within segment Deep River 1, the predicted growing season average concentration of
chlorophyll a ranges from 83 to 117 µg/l, with nuisance conditions with concentrations greater
than 40 µg/l present for more than 84 percent of the growing season. In segment Deep River 2
the growing season average concentration is predicted to be slightly less than 40 µg/l, but
nuisance conditions are predicted to occur on between 25 and 37 percent of days during the
Piedmont Triad Regional Water Authority 2-9
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
growing season. Thus nutrient reductions from current load rates are needed to meet water
quality standards in the Deep River 1 segment. The Muddy Creek 1 segment is also predicted to
experience nuisance blooms at a rate slightly above the 5 percent goal.
Nutrient Reduction Goals for Existing Conditions
Eutrophication in lakes is usually controlled through reduction of phosphorus loads, as this is
most commonly the nutrient limiting algal growth and nitrogen is more difficult to control, as it
has significant ground water and atmospheric loading pathways. Given the assumptions that
WWTP phosphorus loading is 75% orthophosphate (the approximate composition of wastewater
effluent) an approximate loading capacity for phosphorus in the Deep River 1 segment may be
calculated. When total nitrogen concentration in the WWTP effluent is at current levels of
approximately 20 mg/1, the loading capacity for phosphorus in the Deep River 1 segment needed
to achieve the nuisance frequency goal is approximately 1,800 kg/yr during an average flow year.
This results in a predicted average chlorophyll a concentration in this segment of 18 µg/1, and a
nuisance frequency of 5 percent. During a low flow year, the loading capacity for phosphorus in
Deep River 1 to achieve the nuisance frequency goal is only about 600 kg/yr. The low loading
capacity reflects the small dilution capacity present in this narrow, relatively shallow segment.
The loading capacity is inversely related to the rate of flow through this segment, with lower
flows resulting in longer residence and greater utilization of the nutrients by algae. During a
high flow year the loading capacity of the Deep River 1 segment is approximately 2,800 kg/yr.
Estimated phosphorus loads to this segment under existing conditions are on the order of 60,000
kg/yr, and direct loading to this segment from nonpoint sources alone is estimated to be from 4 to
10 times the loading capacity. These findings suggest that it will be difficult or infeasible to
achieve the nuisance frequency goal within the Deep River 1 segment, due to the natural
hydraulic characteristics of the proposed lake.
Nuisance frequency goals are also predicted not to be met within the Muddy Creek 1 segment.
This segment is primarily affected by nonpoint loads, and it was assumed that phosphorus
loading was 50% orthophosphate. Nitrogen loads were held at existing levels. With these
assumption, the phosphorus loading capacity of the Muddy Creek 1 segment is approximately
780 kg/yr under low flow conditions, 1,700 kg/yr under average flow conditions, and 2,290 kg/yr
under high flow conditions. The loading capacity under average flow is slightly greater than the
phosphorus loading under existing conditions shown in Table 4, yet a nuisance frequency of
5.1 % is predicted. This is due to the presence of a small amount of domestic-type wastewater
discharge to this segment, the effluent of which is assumed to contain greater than 50 percent
bioavailable orthophosphate, thus creating a slightly greater algal response than assumed for the
calculation of assimilative capacity. The Melbille Heights discharge to this segment will be
connected to the municipal sewer by PTRWA as part of the Nutrient Reduction Strategy.
Given these assumptions, reductions from existing levels of phosphorus loading needed to
achieve loading capacity are summarized below:
2-10 Piedmont Triad Regional Water Authority
•
Draft (February 1998) Section 2 - Nutrient Reduction Goals and Objectives
0
(* Assumes WWTP effluent is 75% orthophosphate, nonpoint loading is 50% orthophosphate,
and nitrogen concentration in High Point Eastside effluent is 20 mg/1.)
Total Phosphorus Nutrient Loading Reduction Goals for the Randleman Lake
Watershed (kg/yr)*
Lake Segment Low Flow Year High Flow Year Average Flow Year
Deep River 1 60,100 63,860 61,800
Muddy Creek 1 20 440 0
2.3.2 Analysis of Future Conditions without Water Supply Protection
As the Triad area continues to grow and develop, both point and nonpoint sources of nutrient
load to the proposed reservoir will also change. Changes to point sources include expansion of
the High Point WWTP, and potential elimination of some minor discharges. Nonpoint sources
will change as land is converted from rural uses to residential and commercial uses. Rates of
withdrawal for water supply from the reservoir will also increase. These changes will affect both
pollutant loading and flows. The combined effects of changes in load and alteration in flow
through the reservoir can be analyzed with the water quality model described above.
Future conditions in the watershed and reservoir are analyzed at approximately year 2025. This
date was chosen because land use predictions for 2025 have been developed as part of the
Piedmont Triad Regional Transportation Study.
WWTP and WTP Expansion
The High Point Eastside WWTP will expand in the near future to a design capacity of 26 MGD
that the facility is expected to reach by the year 2020. This expansion will be accompanied by
additional reductions in nutrient concentration and load, as described in Section 3.1.1. The
expected permit limits without additional reduction efforts are expected to be 1 mg/1 total
phosphorus and 6 mg/1 total nitrogen (summer). The corresponding total phosphorus and total
nitrogen loads are:
Effluent flow of 16 MGD Effluent Flow of 26 MGD
Total Phosphorus 22,110 kg/yr 35,950 kg/yr
(48,750 lb/yr) (79,270 lb/yr)
Total Nitrogen 132,640 kg/yr 215,690 kg/yr
(292,480 lb/yr) (475,590 lb/yr)
At the same time, withdrawals from Randleman Lake by the water treatment plant will also
increase, changing flow patterns in the lake, reaching a design capacity of 48 MGD by 2040.
Piedmont Triad Regional Water Authority 2-11
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
Withdrawals by the WTP will remove a significant amount of nutrient mass from the lake.
During an average flow year with future land use without water supply protection ordinances and
the WWTP operating at capacity, the WTP is predicted to remove 460 kg of phosphorus and
8,210 kg of nitrogen per year.
Minor Dischargers
It is assumed that no new domestic-type wastewater discharges will be permitted by the State
within the Randleman Lake watershed. It is also assumed that permitted flow will not be
increased on existing permits.
Future Land Use
Increased population and economic development in the Piedmont-Triad area will result in
changes in land use, including a shift from rural (forest, agriculture) to urbanized (residential,
commercial, industrial) uses. The dominant existing land use of undeveloped portions of the
watershed is forest (see Table 3), which provides low per-acre loadings of nutrients. To the
extent that forest land use is converted to urbanized land uses increases in nutrient loading will
occur. Increased impervious surface cover accompanying urbanization will also change runoff
patterns.
Changes in land use will occur as a result of the interaction of demand and water supply
protection efforts. Changes will be greatest, and water supply protection ordinances most
important, where development pressure is strongest; where development pressure is weak change
will come slowly, and water supply protection ordinances will be less critical.
Some parts of the Randleman Lake watershed are expected to experience rapid growth,
particularly the area between High Point and Greensboro. Other parts of the watershed, such as
the rural parts of Randolph Co. north of Randleman, are expected to remain largely rural and will
not approach buildout capacity within the foreseeable future.
To distinguish areas of high and low development pressure we used projections for year 2025
developed for the Piedmont Triad Regional Transportation Study, as shown in Figure 4. Areas
of the watershed predicted to be key "living areas" and "working areas" by 2025 in this study
were assumed to be near fully developed (90% of buildout capacity), while outlying areas were
assumed to experience a 20% increase in housing units over current conditions, consistent with
the expected rate of population increase in the watershed by 2025. Future conditions for the
analysis are thus based on approximate 2025+ conditions. Longer term projections are not
available.
Methods for estimating future land use changes, with or without water supply protection efforts,
are described in Appendix II. Table 6 summarizes the future land use distribution expected
without water supply protection ordinances for Randleman Lake, but including existing water
2-12 Piedmont Triad Regional Water Authority
Draft (February 1998) Section 2 - Nutrient Reduction Goals and Objectives
•
•
•
Figure 4. Randleman Lake Watershed High Growth Areas for Year 2025
Piedmont Triad Regional Water Authority
2-13
County Boundaries 1 0 1 2 3 4 Niles
Watersheds
M Projected Working Areas
Projected Living Areas
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
supply protection ordinances for the Oak Hollow, City Lake, and Oakdale watersheds.
Concentrations in effluent from the High Point Eastside WWTP are assumed to continue at
current concentrations as flow increases. Predicted nutrient loads and chlorophyll a response are
shown in Tables 7 and S.
For average flow conditions, total phosphorus load is predicted to decline slightly from existing
conditions, representing the reduction in WWTP effluent from 4 mg/1 to 1 mg/1 total phosphorus.
Total nonpoint phosphorus loads at average flow, however, are predicted to more than double,
from 18,900 to 39,640 kg/yr. Nonpoint nitrogen loads are also predicted to increase significantly
in the absence of a nutrient reduction strategy.
Chlorophyll a concentrations predicted for future conditions without a nutrient reduction strategy
show a significant reduction versus predictions for existing conditions in segments Deep River 1
and Deep River 2. Again, this is due to the decrease in phosphorus concentration in the WWTP
effluent, which is assumed to be required regardless of whether a nutrient reduction strategy for
Randleman Lake is implemented. In addition, increased through flow rate in these segments
associated with increased impervious surface and increased flow from the WWTP helps flush
excess nutrients out of the upstream segments of the lake. Within other lake segments,
chlorophyll a concentrations are predicted to increase in future due to increased nonpoint source
loading of nutrients. For instance, the average chlorophyll a concentration in segment Muddy
Creek 1 is predicted to increase from 17 to 28 µg/1 during an average flow year.
Impact of Predicted Future Conditions on Nutrient Reduction Goals 0
Predictions for future conditions without a nutrient reduction strategy continue to meet two of the
three chlorophyll a management goals: The lakewide average concentration is predicted to be
less than 25 µg/l and the concentration in the water intake segment (Deep River 3B) is less than
15 µg/1. However, the frequency of nuisance conditions (chlorophyll a concentrations greater
than 40 [41) is predicted to exceed 5% within four segments of the proposed Randleman Lake
(Deep River 1, Deep River 2, Deep River 3A, and Muddy Creek 1). The frequency is predicted
to increase relative to existing conditions in Deep River 3A and Muddy Creek 1.
Predicted future conditions without a nutrient reduction strategy are closer to meeting goals
within the Deep River 1 segment than under existing conditions (due to the reductions in the
WWTP effluent nutrient concentrations), but still far in excess of target levels. Increased
degradation is predicted for the Muddy Creek 1 segment. A nutrient reduction strategy is needed
to improve conditions in both segments.

2-14 Piedmont Triad Regional Water Authority
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Table 7. Estimated Nutrient Loads by Lake Segment (kg/yr) for Future Conditions,
without Nutrient Reduction Strategy,
WWTP at 26 MGD, 1 mg/l Total Phosphorus, and 6 mg/1 Total Nitrogen
Segment Low Flow Year High Flow Year Average Flow Year
P N P N P N
Oak Hollow 3,780 34,830 10,690 103,320 6,980 69,250
City Lake 3,080 28,210 9,660 93,710 5,710 57,470
Deep River 1 (NPS
and minor PS) 6,140 49,690 15,480 137,800 10,460 93,170
Deep River 1 (WWTP) 35,950 215,690 35,950 215,690 35,950 215,690
Deep River 2 4,040 36,520 10,860 104,490 7,040 70,190
Deep River 3A 1,190 10,430 2,290 27,120 1,630 17,720
Deep River 3B 140 2,210 460 7,030 270 4,320
Muddy Creek 1 4,150 35,460 10,220 90,160 65400 58,220
Muddy Creek 2 190 2,640 830 10,580 470 6,520
Near Dam 270 3,480 1,220 14,950 700 9,350
TOTAL 58,940 419,160 975670 804,840 75,590 601,900
Total Nonpoint Source 22,990 203,470 61,720 589,150 39,640 386,190
Table 8. Chlorophyll a Predictions for Future Conditions,
without Nutrient Reduction Strategy
Segment Low Flow Year High Flow Year Average Flow Year
Chl a
(µg/1) Nuisance
Frequency Chl a
(µg/1) Nuisance
Frequency Chl a
(µg/1) Nuisance
Frequency
Oak Hollow 15 2.3% 17 3.6% 17 3.3%
City Lake 22 9.0% 23 9.8% 23 10.4%
Deep River 1 95 89.3% 71 76.2% 80 82.5%
Deep River 2 36 32.1% 30 22.0% 33 26.1%
Deep River 3A 20 6.8% 19 5.7% 19 6.1%
Deep River 3B 14 1.9% 13 1.4% 14 1.6%
Muddy Crk 1 28 18.1% 28 17.7% 28 18.0%
Muddy Crk 2 14 1.6% 15 2.5% 15 2.0%
Near Dam 10 0.3% 13 1.3% 12 0.8%
Lake Randleman
Average 23 21 22
0,
•

2-16 Piedmont Triad Regional Water Authority
Draft (February 1998) Section 3 - Nutrient Reduction Strategy
0 3. NUTRIENT REDUCTION STRATEGY
The Nutrient Reduction Strategy is divided into two program areas: control of point source
nutrient loads, and control of watershed nonpoint source nutrient loads. To address predicted
water quality problems within the Deep River 1 segment the emphasis must be placed on point
source reductions, as the High Point Eastside contributes the bulk of nutrient load to this
segment. For the Muddy Creek 1 segment there are no significant point sources, so the emphasis
must be on nonpoint source controls.
3.1 Point Source Nutrient Control Program
3.1.1 Enhanced Phosphorus Removal at High Point Eastside WWTP
Under existing operations, the High Point Eastside WWTP has achieved approximately 4 mg/1
total phosphorus and 20 mg/1 total nitrogen (summer), for a total load of 58,070 kg/yr of
phosphorus and 290,350 kg/yr of nitrogen. New permit limits are currently being negotiated for
the plant. As part of the strategy for protecting the proposed Randleman Lake, it is expected that
these will include a 0.5 mg/1 limit for total phosphorus and a 6 mg/1 total nitrogen (summer only)
limit. PTRWA proposes to enter into an interlocal agreement with the City of High Point as
provided for in G.S. 160A-460 that will establish an operating goal of 0.2 mg/1 total phosphorus
for the Eastside plant. The interlocal agreement will serve to create a financial incentive for the
City of High Point to provide this higher level of treatment. The incentive payment by the
Authority will be based on the projected higher cost of treatment for this lower phosphorus
concentration. The agreement will also provide for a review and extension of the financial
incentive, if necessary, coincident with the permit renewal cycle for the Eastside plant.
The enhanced treatment levels of 0.2 mg/l total phosphorus and 6 mg/1 total nitrogen (summer),
represent a 20-fold reduction in phosphorus and a 3-fold reduction in nitrogen for a near-term
discharge of 16 MGD. By the time the plant reaches expected buildout capacity of 26 MGD, the
additional treatment will still result in a phosphorus load 88 percent less than that currently being
discharged from the plant. Nutrient loads for the WWTP are summarized in Table 9, and the
reduction in phosphorus load is shown graphically in Figure 5. Loads with the Nutrient
Reduction Strategy in place are compared to loads with an effluent limit of 1 mg/1 total
phosphorus as assumed for the analysis of future conditions without water supply protection
(Section 2.3.2).
Given an assimilative capacity at average flow of 1,800 kg/yr phosphorus within the Deep River
1 segment, and predicted future loads to this segment of 46,400 kg/yr without a nutrient
reduction strategy, a reduction in loading of 44,600 kg/yr would be needed to meet all water
quality goals. The improvements to the WWTP accomplish a reduction of 28,760 kg/yr, or 64
percent of the needed reductions.
•
Piedmont Triad Regional Water Authority 3-1
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
60,000
50,000
40,000
m
0
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2
0
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CL
0 20,000
L
CL
10,000
0
r-xistmg t.oaa k IU.a iviuu at 4 mgn) rutura t.oaa kco muu at U.,d mgn)
Figure 5. Annual Phosphorus Loads from High Point Eastside WWTP
Table 9. Future High Point Eastside WWTP Nutrient Loads (kg/yr)
Operating Condition Total Phosphorus Total Nitrogen
10.5 MGD at 4 mg/1 P, 20 mg/1 N 58,030 290,150
16 MGD at 1 mg/l P, 6 mg/l N 22,110 132,640
26 MGD at 1 mg/l P, 6 mg/1 N 35,950 215,690
16 MGD at 0.2 mg/l P, 6 mg/1 N 4,420 132,640
r26 MGD at 0.2 mg/1 P, 6 mg/1 N 7,190 215,690
3.1.2 Potential for Control of Minor Dischargers
The majority of the minor "domestic-type" permitted wastewater discharges within the watershed
of the proposed Lake Randleman are in areas for which no sewer extension is planned.
Currently, PTRWA has committed to remove two minor discharges-Melbille Heights and
Hidden Forest-by connecting their effluent to municipal sewer systems. For analysis of future
3-2 Piedmont Triad Regional Water Authority

E
f
1.
Draft (February 1998) Section 3 - Nutrient Reduction Strategy
conditions with nutrient reduction strategies it is assumed that these two dischargers will be
connected to the municipal sewer system, removing a total of 0.135 MGD in permitted flow.
This would result in an estimated reduction of 910 kg/yr total phosphorus and 3640 kg/yr total
nitrogen loading. Other existing minor dischargers falling within areas of future sewer extension
will be evaluated for discharge removal on a plant-by-plant basis. There are three minor
dischargers located within the boundaries of the future sewer service area of Greensboro. These
are Hickory Run Mobile Home Park (Bull Run Creek), and Plaza and Crown Mobile Home
Parks (Hickory Creek), all of which drain to the Deep River 1 segment of the proposed
Randleman Lake.
3.2 Nonpoint Source Control Program
Additional nutrient reductions will be achieved through a nonpoint source control program.
Within the downstream segments of the lake the nonpoint source control program provides
additional actions to help prevent exceeding assimilative capacity. Within the upstream
segments Deep River 1 and Muddy Creek 1, where assimilative capacity is expected to be
exceeded, the Nutrient Reduction Strategy for nonpoint sources will focus on preventing
additional degradation of water quality.
The Nutrient Reduction Plan for nonpoint sources contains five major components. First are the
watershed protection ordinances which restrict density of development and types of land use in
the watershed, as described in Section 3.2.1. Other components include structural controls on
• load generation from specific land uses (Section 3.2.2), non-structural controls on load
generation (Section 3.2.3), education and outreach programs (Section 3.2.4), and monitoring and
enforcement (Section 3.2.5).
3.2.1 Watershed Protection Ordinances
Basis in State Regulations
Approximately 50 % of North Carolina's population depends on rivers and lakes for drinking
water as well as commercial and industrial uses. In the last decade, the state and many local
governments recognized the need to rely not just on treating drinking water to remove chemicals
and pathogens but also on preventing pollution from entering water supplies. Responding to the
growing demand on the state's surface water supplies and growing concern about degradation of
surface water sources by nutrients and other pollutants, the NC General Assembly passed the
Water Supply Protection Act of 1989 (NCGS 143-214.5). The Act requires all local
governments that have land use jurisdiction within surface water supply watersheds to implement
and enforce nonpoint source pollution management according to minimum standards adopted by
the state. The water supply standards for managing nonpoint source pollution apply to local
governments' urban development and to agricultural, silvicultural, and Department of
Transportation activities in the watershed.
•
Piedmont Triad Regional Water Authority 3-3
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
In the State's Water Supply Watershed Protection standards, there are five water supply classes
(WS-I to WS-V) that are defined by the existing intensity of land use and types of permitted
wastewater discharges. The WS-1 watersheds are the least disturbed and have the most stringent
minimum requirements for future water quality protection. WS-IV watersheds have an urban
character and less stringent controls on future development. (WS-V watersheds are those that
local governments have designated as future water supply sources but currently have no water
supply withdrawal.)
The standards require dual action by state and local governments. By classifying a watershed as
a water supply, all local governments within the watershed must take action to control nonpoint
sources of pollution through housing density controls, limits on impervious area in a
development, buffers along streams, stormwater control requirements for higher density
development, and other means of reducing the potential contamination of the water supply. In
turn, the state limits the point source discharges that can locate within the watershed.
Watershed Overlay Districts
The Randleman Lake watershed contains three smaller water supply watersheds: Oakdale, City
Lake, and Oak Hollow Lake watersheds, all classified as WS-IV (Figure 6). The relevant
jurisdictions of Guilford Co., Forsyth Co., High Point, Jamestown, Kernersville, and Greensboro
all have approved water supply protection ordinances in place for these watersheds.
•
Seven jurisdictions have area in the watershed which drains directly to the proposed Randleman
Lake, and not to the upstream City Lake and Oak Hollow watersheds. These are: Guilford Co.,
Greensboro, High Point, Jamestown, Randolph Co., Archdale, and Randleman. Guilford Co.,
Greensboro, Randolph Co., and Archdale have all adopted water supply watershed overlay
districts and water supply protection ordinances for the proposed Randleman Lake. Guilford Co.
and Greensboro have designated the water supply watershed overlay district for Randleman Lake
(referred to as Randleman Dam watershed) as a WS-IV classification. Much of the watershed
lying in Randolph Co. is currently undeveloped, and Randolph Co. and Randleman have
voluntarily adopted a higher degree of protection, defining the overlay district as WS-III.
High Point has existing WS-IV watershed overlay districts for City Lake and Oak Hollow Lake.
For areas within High Point's zoning jurisdiction draining directly to Randleman Lake, High
Point has agreed to adopt Guilford County's watershed protection ordinances, which are more
stringent than the state minimum for WS-IV. These more stringent ordinances will also be
applicable in the existing Oakdale watershed overlay district. Jamestown and Archdale have not
yet adopted watershed overlay districts for the proposed reservoir. These jurisdictions, however,
have existing WS-IV water supply protection ordinances for other watersheds, and it is assumed
that similar ordinances will be adopted for Randleman Lake. The status of watershed overlay
districts for the Randleman Lake watershed and upstream watersheds is shown in Table 10.
3-4 Piedmont Triad Regional Water Authority
Draft (February 1998) Section 3 - Nutrient Reduction Strategy
0
•
ty
_ Ldrmb
Critical Area (Randolph County)
tical Area Tiers (Guilford County)
1 1 0 1 2 3 4 5 Niles
2
3
4
Figure 6. Existing Water Supply Watersheds in the Randleman Lake Watershed
0
Piedmont Triad Regional Water Authority 3-5
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
Table 10. Existing Watershed Overlay Districts for Randleman Lake Watershed.
Jurisdiction Applicability Critical Area (CA) Protected Area (PA)
Guilford County Randleman Dam (Lake) Not less than '/2 mile from the Balance of the reservoir
High Point (City Lake) normal pool elevation of reservoir. watershed.
Oak Hollow Lake Tiers defined within CA:
Tier 1: within 200 ft of normal
pool elevation of reservoir
Tier 2: 200-750 ft
Tier 3: 750 ft-3000 ft, not to
exceed CA boundary
Tier 4: between Tier 3 and
Guilford CA boundaries
Greensboro Randleman Dam (Lake) Not less than '/2 mile from the Balance of the reservoir
High Point (City Lake) normal pool elevation of reservoir. watershed.
Tiers: defined as in Guilford
County
High Point Oak Hollow Lake To the ridgeline of reservoir; for All land within
City Lake major feeding streams, not less jurisdiction that drains
Oakdale Watershed than 2,750 ft upstream. to reservoir and falls
(Randleman Lake:Guilford Tiers: defined as in Guilford outside of Critical Area
County ordinances County, except that Tier 3 extends
proposed for adoption) to 2,750 ft
Jamestown High Point (City Lake) To the ridgeline of reservoir; for All land within
Oakdale Watershed major feeding streams, not less jurisdiction that drains
(Randleman Lake: not yet than 2,750 ft upstream. to reservoir and falls
adopted) ie s: defined as in Guilford outside of Critical
County, except that Tier 3 extends Area.
to 2,750 ft
Randolph County Randleman Lake Defined on Randolph County's Balance of the reservoir
Watershed Protection Map; must watershed.
meet State requirement of/Z mile
and draining to reservoir.
Randleman Randleman Lake Defined on Randleman's Balance of the reservoir
Watershed Protection Map; must watershed.
meet State requirement of/z mile
and draining to reservoir.
Archdale (Randleman Lake: not yet Not applicable.
adopted)
Forsyth County Oak Hollow Lake Not applicable. (Approximately '/z Balance of the reservoir
mile of normal pool of reservoir) watershed.
Kernersville Oak Hollow Lake Not applicable. Balance of the reservoir
watershed.
3-6 Piedmont Triad Regional Water Authority
L?- I

Draft (February 1998) Section 3 - Nutrient Reduction Strategy
In keeping with the state's watershed protection rules, ordinances in all of the jurisdictions define
• two overlay districts: a Critical Area near the water supply (in which the most stringent land use
controls are required) and a Protected Area. The state rules require the Critical Area to include
all land within '/z mile of and draining to a water supply reservoir; Table 10 shows that all of the
jurisdictions meet this rule in the existing ordinances. Guilford County has adopted a Critical
Area that in some areas goes beyond the state-required '/Z mile minimum. In all of these
jurisdictions, the Protected Area has been defined as the balance of the reservoir's watershed
falling outside of the Critical Area, which meets the State requirement for WS-III watersheds and
exceeds the requirement for WS-IV watersheds.
In the Guilford County jurisdictions (Guilford County, Greensboro, High Point, and Jamestown),
four tiers have been delineated within the Critical Area that act as further overlay districts. Tier 4
is outside the state-defined Critical Area but within the Guilford County Critical Area
designation. Table 11 shows the density limits associated with the water supply ordinances.
Projected Future Land Use with Water Supply Protection Ordinances
The water supply protection ordinances place significant restrictions on potential development
within the watershed by controlling the minimum lot size in residential developments and the
maximum allowed areal coverage by buildings, roads, parking lots, and other impervious
surfaces in commercial and industrial developments. However, for some areas in the watershed
expected development is also restricted by other factors, such as lack of demand for
development, presence of public water and sewer, and poor suitability of soils for septic systems.
• The actual impact of the ordinances on future land use must therefore be determined through
careful analysis of the interaction of ordinances, demand, and environmental features. The
methodology used to estimate future land use conditions is described in Appendix II. As with
the estimate of future conditions without water supply protection, the analysis is based on
approximate year 2025+ conditions. Projected future land use with water supply protection
ordinances is shown in, Table 12, which can be compared with Table 5. Figure 7 contrasts
projected 2025+ land use under existing conditions and with and without proposed water supply
projection ordinances. The water supply ordinances result in an increased amount of forest and
open land. Commercial and industrial uses are diminished, with a corresponding shift to forest
and open land by the impervious surface cover limitations in the ordinances. The ordinances will
result in only a small decrease in the total land area in residential uses; however, the residential
land developed with WS-IV ordinances will generally be at lower density and greater lot size.
Table 13 shows the reduction in nutrient loads expected to be achieved by water supply
protection ordinances alone, without considering other nonpoint source control strategies. The
water supply protection ordinances are predicted to result in a net reduction of 6,250 kg/yr total
phosphorus (19% of the nonpoint source load) and 36,800 kg/yr total nitrogen (11% of the
nonpoint source load) during an average flow year. The greatest reductions are achieved in those
subwatersheds subject to growth pressure; little savings occur in areas such as Muddy Creek 2
where little growth is expected. No reductions are indicated for Oak Hollow and City Lake
watersheds because water supply protection ordinances for these watersheds are already in place.
Piedmont Triad Regional Water Authority 3-7
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Draft (February 1998) Section 3 - Nutrient Reduction Strategy
LJ
Existing Conditions
Commercial/Industrial(l (7%)
Residential (16%) L:'u ?.J
Forest (54%)
•
0
Agriculture (21%)
Open (2%)
Future, with Ordinances
Commercial/ Forest (24%)
Industrial (8%)
Residential (51 %)
Open (11 %)
Agriculture (6%)
Residential (52%)
Figure 7. Existing and Projected 2025+ Land Use for Randleman Lake Watershed
Table 13. Estimated Reduction in Nonpoint Nutrient Loads by Lake Segment (kg/yr)
Achieved by New Water Supply Protection Ordinances
for Future Land Use Conditions
Segment Low Flow Year High Flow Year Average Flow Year
P N P N P N
Oak Hollow 0 0 0 0 0 0
City Lake 0 0 0 0 0 0
Deep River 1 1,740 12,360 2,990 18,220 1,940 11,620
Deep River 2 1,750 12,370 3,710 20,690 2,290 12,950
Deep River 3A 170 2,430 320 4,540 210 2,840
Deep River 3B 50 700 90 1,310 60 820
Muddy Creek 1 1,360 7,840 2,590 11,670 1,640 7,660
Muddy Creek 2 10 100 20 210 10 130
Near Dam 60 520 160 1,280 100 780
TOTAL 5,130 36,330 9,870 57,920 6,250 36,800
Future, without Ordinances
Commercial/ Forest (21%)
Industrial (16%)
Open (5%)
Agriculture
(6%)
Piedmont Triad Regional Water Authority 3-11
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
For the Deep River 1 segment, the water supply protection ordinances provide a reduction of
1,940 kg/yr total phosphorus during an average flow year, or 3 percent of the needed reductions
to meet assimilative capacity in this segment.
3.2.2 Structural Controls on Loads
The second component of the strategy for reducing loads from nonpoint sources is use of
structural controls on loads. Given that land uses associated with increased pollutant loads will
be present, structural controls are designed to trap or isolate pollutants before they can reach the
reservoir.
Regional Stormwater Ponds
CDM (1989) conducted a watershed management study to design ways to improve the protection
of Oak Hollow and City Lake watersheds. This report recommended establishing a regional
BMP Master Plan to mitigate the impacts of NPS pollution loading into High Point's reservoirs.
Specific recommendations included 72 detention ponds (62 wet, 10 dry), of which 33 ponds
would be located in City Lake watershed and 39 ponds in Oak Hollow Lake watershed. The goal
of these detention ponds would be to reduce nonpoint source loading from existing and future
development. In addition, the ponds would provide retention and containment capabilities for
any potential hazardous material spills.
High Point began to implement the CDM recommendations for stormwater ponds on a pond-by-
pond basis. After permitting four of the ponds, USACE required that High Point document the
cumulative impacts on wetlands of all 72 of the ponds simultaneously to obtain necessary
permitting, rather than permitting ponds individually. High Point contracted with HDR to study
the permittability of the remaining 68 proposed ponds, and chose not to pursue a single permit
for financial reasons.
At present there are four regional detention ponds which have been constructed in the High
Point/Guilford County area (see Figure 8). The four sites are Piedmont Lake, Davis Lake,
Regency Lake,. and the Oak Hollow Mall Lake. The purpose of these four facilities is to provide
storm runoff protection and improved water quality for the City of High Point's two existing
water supplies: Oak Hollow Lake and City Lake. A fifth site is in the planning stage.
The Piedmont Lake facility is located north of High Point on Piedmont Parkway between NC
Highway 68 and Tarrant Road on the East Fork of Deep River. The watershed contributing to
the Piedmont Lake facility consists of 1,200 acres of medium density single family, commercial,
office, and woodland areas. This watershed also includes the petroleum tank farm at Friendship
along the I-40, railroad, and Piedmont-Triad International Airport corridor. The Piedmont Lake
facility has a normal pool elevation of 806 msl, a maximum water surface elevation of 816.3 msl,
a corresponding total storage volume of 304 acre-feet, and a total surface area of approximately
12 acres. Due to the potential for spills from the tank farm, Piedmont Lake has spill containment
capabilities.
3-12 Piedmont Triad Regional Water Authority
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The Davis Lake facility is located just north of High Point between NC Highway 68 and Tarrant
Road on the East Fork of Deep River. The watershed contributing to the Davis Lake facility
consists of 1,258 acres of mainly woodland and agricultural land uses, with some industrial and
commercial development appearing in the past several years. Davis Lake has a normal pool
elevation of 794 msl, a maximum surface elevation of 800.4 msl, a corresponding total storage
volume of 310 acre-feet, and a total surface area of 22 acres.
The Regency Lake facility is located north of High Point between Gallimore Dairy Road and
Regency Drive, east of NC Highway 68 on the East Fork of the Deep River. The watershed
contributing to the Regency Lake facility consists of 4,095 acres of industrial, commercial,
office, and medium density residential land uses. Regency Lake has a normal pool elevation of
792 msl, a maximum water surface elevation of 799 msl, a corresponding storage volume of 90
acre-feet, and a total surface area of approximately 4 acres.
The Oak Hollow Mall facility is located in High Point between Johnson Street and Eastchester
Drive, southeast of the Oak Hollow Mall. The watershed contributing to the Oak Hollow Mall
facility consists of 742 acres of medium density single family, multi-family residential,
commercial, office, and institutional land uses, and includes the northern segment of the North
Main Street corridor from Lexington Avenue north of Highway 68. The Oak Hollow Mall
facility has a normal pool elevation of 814.8 msl, a maximum water surface elevation of 822 msl,
a corresponding total storage volume of 163 acre-feet, and a total surface area of approximately 8
acres.
The City of High Point also plans to construct a fifth storm water treatment facility. The
proposed Skeet Club Road facility, which is scheduled to begin construction in the near future,
will be situated on the West Fork of the Deep River at the outermost reach of Oak Hollow Lake.
The watershed contributing to this proposed facility consists of approximately 9,800 acres of
urban and rural housing development, commercial, institutional, and agricultural land uses. The
Skeet Club Road facility will consist of an impoundment and containment structure which will
create approximately 11 acres of constructed/enhanced wetlands. A sediment forebay will
provide approximately 21,000 cubic yards (4.25 million gallons) of storage volume. The
proposed facility is currently being re-designed by the City's consultant, and construction is
scheduled to be completed by the summer of 1998.
For developments requiring stormwater control occurring in an area that is already controlled by
one of the existing ponds, the developer has the option of paying a share of costs of the existing
pond. If there is no stormwater detention already existing then the developer must construct one
on site.
WRRI conducted a study of pollutant trap efficiency in High Point's Davis and Piedmont Ponds
(Borden et al., 1996). They found that the ponds were capable of removing an average of 43
percent of influent phosphorus load and 26 percent of the influent nitrogen load. Four of the five
ponds have already been constructed, and do not represent an additional reduction in nutrient
! _
3-14 Piedmont Triad Regional Water Authority
Draft (February 1998) Section 3 - Nutrient Reduction Strategy
load. These ponds are included in the model simulations for future conditions both with and
without a nutrient reduction strategy. The fifth, proposed pond (Skeet Club Road facility) is
estimated to provide an additional reduction in loading to Oak Hollow Lake of 1,281 kg/yr total
phosphorus and 6,648 kg/yr total nitrogen under average flow conditions.
Constructed Wetlands
Uncontrolled stormwater runoff can accelerate erosion and downstream flooding, and transport
large amounts of nutrients and other pollutants to receiving waters. Control of runoff, with
opportunity for trapping and deposition of pollutants, can provide a significant reduction in
nutrient load. One alternative to the use of wet detention ponds for runoff control is use of
constructed or enhanced wetlands. Where runoff passes through a wetland, the force of the
flowing water is reduced, less particulate material is transported, and the pollutant load delivered
downstream is reduced.
Construction and operation of Randleman Lake would impact, principally by inundation,
approximately 121 acres of wetlands. As required under Section 404 of the Clean Water Act,
PTRWA is addressing the loss of these wetlands through the implementation of a mitigation
program that includes the acquisition and permanent conservation of approximately 700 acres of
swamp forest located along the Black River and the creation/restoration of approximately 120
acres of forested wetland along tributaries of the Deep River. The 120 acres will be located in
areas that would also provide water quality benefits, reducing loading to Randleman Lake from
upstream sources of pollution.
Davis-Martin-Powell & Associates has conducted a feasibility study on the use of constructed
and enhanced wetlands to reduce nutrient loading to Randleman Lake. Nine candidate wetland
mitigation sites were initially identified. From this list six sites were identified on which
constructed/enhanced wetlands will be created. These sites will either be constructed directly by
PTRWA or by the State under the Wetland Restoration Enhancement Program (WREP) if the
Authority elects to pay into this wetland bank. These are shown in Table 14 and Figure 9.
Table 14. Proposed Constructed / Enhanced Wetlands
Site Surface Area (acres) Drainage Area (acres)
Richland Creek/Eastside WWTP 38.1 9,979
Reddicks Creek 23.2 5,900
Hickory Creek 33.9 6,211
Upper Muddy Creek 16.6 2,020
Kersey Valley 7.0 450
Buttke Dairy 2.8 429
TOTALS 121.6 24,989
0
Piedmont Triad Regional Water Authority 3-15
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Draft (February 1998) Section 3 - Nutrient Reduction Strategy
Each constructed/enhanced wetland site will consist of low head dams as necessary to maintain a
normal water depth of -6" to +18" above natural ground level throughout the site. Some minimal
grading will be required to shape the constructed wetland and obtain the desired normal pool
depth, but the intent is to preserve the existing bottomland hardwood forests common to these
sites and replace the undergrowth with aquatic plants native to the wetland environment. The
types of vegetation that can be established will depend on the depth of water and how frequently
the areas will be inundated. A planting plan will be developed during the design of the wetlands
to coincide with the grading and site plans.
In general, wetlands designed for water quality treatment can provide significant nitrogen
removal through plant uptake and denitrification. Their performance for phosphorus removal is
highly variable (MWCOG, 1992).
The Water Pollution Control Federation (Schueler et al., 1990) provides guidelines for use of
wetlands for nitrogen removal. To achieve significant (> 50%) nitrogen removal they
recommend a minimum wetland surface area of 4 hectares (10 acres) per 1,000 m' of average
daily flow to provide sufficient retention time and trapping capability. Average daily flows to
the proposed wetlands range from about 10,000 to 50,000 m'/d-which would require wetland
areas of 100 to 500 acres for effective treatment. The areas of the proposed wetlands range from
17 to 38 acres, so only a small amount of pollutant removal is expected.
Based on data summarized in Novotny and Olem (1994), minimal nutrient removal capabilities
of 10% of influent total nitrogen and 5% of influent total phosphorus are assigned to these
wetlands for scoping purposes. Total estimated removal of nutrient load under average flow and
future land use conditions with water supply ordinances is as follows:
Sub-watershed Total Phosphorus (kg/yr) Total Nitrogen (kg/yr)
Deep River 1 590 9,200
Deep River 2 220 5,040
Muddy Creek 1 70 1,250
Muddy Creek 2 10 130
TOTAL 890 15,620
Urban Stormwater and Development Stormwater Controls
None of the municipalities in the watershed have large-scale centralized stormwater collection
systems or stormwater utilities operating or planned for the Randleman Lake watershed. For the
majority of the most urbanized areas (in and around High Point and Jamestown), there are no
piped stormwater collection systems, mainly diffuse drainage. New developments are subject to
stormwater control under the Watershed Ordinances discussed above. Most commercial and
industrial development prior to the Watershed Ordinance does not have any type of onsite
stormwater retention facilities.
Piedmont Triad Regional Water Authority 3-17
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
Most of the water supply overlay districts for Randleman Lake include a high density option, in
which increased impervious surface coverage is allowed if structural control of stormwater is
included in a project. State Regulations for WS-IV watersheds require controlling runoff from
the first inch of rainfall for the high density option. All jurisdictions within the watershed have
adopted requirements for stormwater controls, as shown in Table 15.
All of the local jurisdictions in the Randleman Lake watershed have ordinances which meet or
exceed the minimum requirements of the state regulations. As shown in Table 15, many of the
localities have stormwater control requirements in Low Density as well as High Density
developments. Greensboro and Kernersville require that the engineered stormwater controls be
designed to control 85% of total suspended solids, in addition to the State requirement of
controlling the first inch of rainfall. It should be noted that several of the jurisdictions (Randolph
County, Randleman, Archdale, and Forsyth County) do not permit High Density development
within the water supply watershed, and therefore do not specify any requirements for stormwater
control. Where stormwater control is required, wet detention ponds are generally the preferred
control method, although some of the ordinances allow for the use of other approved control
methods such as natural infiltration areas.
The effect of the Watershed Ordinance requirements for stormwater control is evident for recent
commercial and industrial development in the City Lake and Oakdale watersheds. Development
prior to the Watershed Ordinance generally does not have any type of onsite stormwater
retention. However, any construction or development which has taken place after the
implementation of the Watershed Ordinance has been required to comply with this ordinance by •
limiting impervious cover or construction onsite detention/treatment ponds. Due to the high land
costs within these watershed areas, most developers have chosen onsite detention facilities as a
method of complying with the ordinance. It is estimated by the City staff that approximately 75
onsite detention ponds for the treatment of stormwater runoff have been constructed within the
designated watershed critical areas. These detention ponds have contributing drainage areas
ranging from 10 to 50 acres. Design standards for these onsite detention ponds are included in
the Watershed Ordinance.
For the purposes of modeling it is assumed that the stormwater detention requirements for high
density development result in water quality equivalent to similar development under the low
density requirements of the water supply ordinances. Therefore, no additional credit for nutrient
removal is assigned to onsite detention ponds.
3.2.3 Non-structural Control on Loads
The third component of the Nutrient Reduction Strategy for nonpoint source loads is non-
structural control. Non-structural controls generally consist of modifications to land
management practices (i.e., use of "Best Management Practices") so that the amount of nutrient
load generated in nonpoint runoff is minimized.
i.
3-18 Piedmont Triad Regional Water Authority
Draft (February 1998) Section 3 - Nutrient Reduction Strategy
•
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Table 15. Stormwater Controls Required by Water Supply Protection Ordinances
Critical Area Balance of Watershed
Low Density Development High Density Development Low Density Development High Density Development
State Regulations No requirements Must control runoff from first No requirements Must control runoff from first
inch of rainfall inch of rainfall
Guilford County It built-upon area 12% or less, Must control runoff from first If site does not score 100, Must control runoff from first
permanent infiltration area or inch of rainfall then control first 1/2" by one 1" of rainfall with wet
runoff control fof first 1/2" of of a number of approved detention pond
rainfall over total drainage methods
area
If built-upon area > 12%,
must control runoff from first
inch of rainfall
Greensboro If built-upon area 12% or less, Control of first 1" of rainfall Not required, but will increase Control of first 1" of rainfall
permanent infiltration area or and 85% of TSS, with wet ability to meet performance and 85°'a of TSS, with wet
runoff control of first 1" of detention pond or other 8MP standards (scoresheet) detention pond or other BMP
rainfall and 85% of TSS
If built-upon area > 12%,
must control runoff from first
inch of rainfall and 85% of
TSS
High Point If <= 1 du/2 ac or 6% built- Wet detention pond or If <= 1 du/2 ac or 6% built- Wet detention pond or
upon area, no specific regional runoff control, in upon area, no specific regional runoff control, in
requirements. compliance with City's requirements. compliance with City's
Stormwater Guidelines Stormwater Guidelines
Other low density may use of Other low density must meet
one of 5 alternate measures, performance standards
in compliance with City's (scoresheet) or apply an
Stormwater Guidelines approved stormwater control
measure
Jamestown If <= 1 du/2 ac or 6% built- Wet detention pond or If <= 1 du/2 ac or 6% built- Wet detention pond or
upon area, no specific regional runoff control, in upon area, no specific regional runoff control, in
requirements. compliance with High Point's requirements. compliance with High Point's
Stormwater Guidelines Stomrwater Guidelines
Other low density may use of Other low density must meet
one of 5 alternate measures, performance standards
in compliance with High (scoresheet) or apply an
Point's Stormwater approved stormwater control
Guidelines measure
Randolph County No specific requirements in NA (no option provided for No specific requirements in NA (no option provided for
the watershed protection high density development) the watershed protection high density development)
ordinances. ordinances.
Randleman No specific requirements in NA (no option provided for No specific requirements in NA (no option provided for
the watershed protection high density development) the watershed protection high density development)
ordinances. ordinances.
Archdale NA (no Randleman Lake NA (no Randleman Lake No specific requirements in NA (no option provided for
Critical Area within Archdale Critical Area within Archdale the watershed protection high density development)
jurisdiction) jurisdiction) ordinances.
Forsyth County None required. Regulations NA (no option provided for None required. Regulations NA (no option provided for
stipulate that impervious area high density development) stipulate that impervious area high density development)
be sited and designed to be sited and designed to
minimize runoff and limit minimize runoff and limit
concentrated runoff. concentrated runoff.
Kemersville NA (no Randleman Lake NA (no Randleman Lake No specific requirements in Wet detention pond designed
Critical Area within Critical Area within the watershed protection to control first 1" of rainfall
Kernersville jurisdiction) Kernersville jurisdiction) ordinances. and 85% of TSS
Agricultural Cropland Best Management Practices (BMPs)
Erosion from cropland can be a significant source of sediment and nutrient loading to water
bodies unless proper management practices are followed. Cropland BMPs are developed as site-
specific systems of practices designed to reduce erosion and nonpoint source pollution. Soil
0
Piedmont Triad Regional Water Authority 3-19
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
erodibility, slope length, cropping factors, and practice factors are all considered in conservation
planning. A combination of rotation, tillage practices, and strip cropping are used to develop the
best system of cropland BMPs. According to NRCS District Conservationists, there are 241
agricultural Soil Erosion Control Plans in the Guilford Co. portion of the watershed, 166 in
Randolph Co., and 50 in the Forsyth Co. portion of the watershed. NRCS estimates that there are
approximately 150 locations within the Guilford Co. portion of the watershed that are registered
as farms but do not have a soil conservation plan. Within the Randolph Co. portion of the
watershed there are estimated to be approximately 250 locations registered as farms which do not
have a soil conservation plan. Forsyth Co. has approximately 25 registered sites without control
plans. Most of the listed sites without plans have either been developed (but not removed from
the list) or consist of pasture land with no tillage occurring on the property.
Most of the Soil Erosion Control Plans are for Subclass "e" crop lands. Subclass "e" land is made
up of soils where the susceptibility to erosion is the dominant limitation for cropland use. A
combination of several conservation practices may be needed on cultivated fields to control
erosion and provide for proper water disposal.
The practices typically used include the following:
• Conservation Cropping Sequence (1-corn, 2-small grain - no till soybeans)
• Conservation Tillage
• Crop Residue Use
• Grassed Waterways
The primary resource concerns that are addressed by these conservation practices are shown in
Table 16.
Table 16. Primary Resource Concerns Addressed by
Agricultural Soil Erosion Control Plans
Erosion
Control Water
Disposal Resource
Management Water
Management Offsite
Effects
Conservation
Cropping Sequence x x x
Conservation Tillage x x x
Crop Residue Use x x x
Grassed Waterways x x x
The current rate of implementation of BMPs on crop land is estimated by NRCS District
Conservationists to be 90%. For future conditions with the Nutrient Reduction Strategy in place
it is assumed that BMP implementation on cropland will be increased to 100%. However, area
in cropland is expected to decline sharply in the watershed, resulting in only a small net
reduction in nutrient load. Estimated reductions in nutrient loads achieved by enhanced
agricultural BMP implementation are shown in Table 17.
3-20 Piedmont Triad Regional Water Authority
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Draft (February 1998) Section 3 - Nutrient Reduction Strategy
•
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Table 17. Estimated Reduction in Nonpoint Nutrient Loads by Lake Segment (kg/yr)
Achieved by Enhanced BMP Implementation on Crop Land
for Future Land Use Conditions
Segment Low Flow Year High Flow Year Average Flow Year
P N P N P N
Oak Hollow 0 0 0 0 0 0
City Lake 0 0 0 0 0 0
Deep River 1 10 50 40 130 30 80
Deep River 2 40 110 140 430 80 240
Deep River 3A 20 60 90 230 50 140
Deep River 3B 10 20 20 70 10 30
Muddy Creek 1 30 80 90 240 50 140
Muddy Creek 2 20 50 110 230 50 120
Near Dam 20 50 130 290 70 150
TOTAL 150 420 600 1,600 330 900
Animal Operations
Concentrated animal operations, such as dairies, can provide significant sources of nutrient input
to water bodies. On June 21, 1996 the NC general Assembly passed Senate Bill 1217, An Act to
Implement Recommendations of the Blue Ribbon Study Commission on Agricultural Waste.
The new law establishes that, effective January 1, 1997, permits are required for operation of
animal waste management systems under a general permit system. This is implemented in the
NC Administrative Code, Section 15A NCAC 211.0200. Under the general permit system,
animal operations are not required to obtain individual permits, but those above the threshold
numbers are required to submit documentation certified by recognized authorities showing they
are complying with regulations established for animal waste systems in the general permit.
Animal waste management systems must have the following components:
• odor BMPs;
• insect control BMPs;
• methods for disposing of dead animals;
• BMPs for riparian buffers or equivalent controls along perennial streams;
• an emergency management plan designed to prevent lagoon failure and to minimize
environmental damage from lagoon overflows;
0
Piedmont Triad Regional Water Authority 3-21
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
provisions for testing waste to determine nutrient content and testing of soils where waste
is to be applied; 0
provisions of a plan for applying waste at a rate that assures a balance between nitrogen
application and nitrogen requirements of crops; and
provisions for keeping records of the required waste and soil testing and waste
application requirements.
The law also establishes a process under which each animal operation must undergo an
operational review and a regulatory inspection at least once per year. The law includes
provisions for fees, special orders of consent for getting an operation into compliance, operator
certification and training, and the permitting schedule. General permits are being issued over a
five-year period, commencing on January 1, 1997.
There are no animal operations within the Guilford Co. portion of the watershed. Within the
Randolph Co. portion of the watershed there are three farms with animal waste management
plans: Buttke Dairy, Cashatt Dairy, and Green Valley Farm. These three farms together have a
design capacity of 1,750 dairy cattle. Nutrient loading from these operations has not been
simulated separately from other agricultural operations; therefore, an explicit nutrient reduction
due to animal waste management has not been included in model predictions. Waste
management plans are, however, important to ensure that these farms do not become a source of
excessive nutrient loads.
Stream Buffer and Setback Requirements 0
State water supply regulations (15A NCAC 2B.0211 (f)(3)(B)(VI)) require the maintenance of a
vegetative buffer between all new development activities and perennial streams draining to a
WS-IV water. The minimum buffer width is 30 feet for low-density development, and 100 feet
for development under the high-density option. No buffer is required for intermittent streams.
All of the local jurisdictions in the Randleman Lake watershed have ordinances which meet or
exceed these minimum requirements, as shown by Table 18. Randolph County and all of the
Guilford County jurisdictions require wider buffers around the reservoir itself. In addition, High
Point and Jamestown require buffers around some intermittent waters (open drainage channels).
Randolph Co., Randleman, and Archdale all specify a 50' buffer width in the critical area. All
buffers are to remain vegetated and undeveloped, with some exceptions allowed for road and
greenway crossings and water-dependent structures.
The stream buffer requirements were assumed to be not significantly different from those in
place in the northern Virginia watersheds from which the nutrient export coefficients were
obtained. Therefore, no additional nutrient reduction component was assigned to the stream
buffer requirements.

3-22 Piedmont Triad Regional Water Authority
Draft (February 1998) Section: 3 - Nutrient Reduction Strategy
•
•
Table 18. Stream Buffer Requirements in Water Supply Protection Ordinances
Around Other Perennial Waters Intermittent Waters
Reservoir
Low Density High Density
Development Development
State Regulations 30' 30' 100' No specific requirements.
Guilford County 200' (Tier 1) 30' 100' No specific requirements.
Greensboro 200' (Tier 1) 30' 100' No specific requirements.
Protected buffer around open
drainage channels. Width
High Point 200' (Tier 1) 30' 100' varies from 10' to 100-year
floodplain contour, depending
on area of drainage basin.
Protected buffer around open
drainage channels. Width
Jamestown 200' (Tier 1) 30' 100' varies from 15' to 100-year
floodplain contour, depending
on area of drainage basin.
Randolph County 100' 50' NA No specific requirements.
Randleman 50' 50' NA No specific requirements.
Archdale 50' 50' NA No specific requirements.
Forsyth County 30' 30' NA No specific requirements.
Kernersville 30' 30' 100' No specific requirements.
Erosion and Sedimentation Ordinances
The NC Sedimentation Pollution Control Act of 1973 addresses the issue of soil erosion and
sedimentation. This act prohibits visible sediment from washing off construction sites. The law
does not specify a rigid set of practices; rather, they require the land developer to prepare an
erosion and sedimentation control plan and employ appropriate measures to meet the
performance standards.
This law is generally administered by the Land Quality Section of NCDENR, but local
governments may gain authority by adopting local sedimentation control ordinances at least as
stringent as the State standards. Greensboro, Guilford County, Jamestown and High Point have
their own sedimentation control ordinances, while Archdale, Randleman, and Randolph County
are regulated by the regional offices of NCDENR.
•
Piedmont Triad Regional Water Authority 3-23
Randleman Lake Nutrient Reduction StrateD, and Implementation Plan Draft (February 1998)
A soil erosion and sedimentation control plan is necessary if the land-disturbing activity: r
1. Exceeds one (1) acre; (State and ordinances)
2. Will take place on highly erodible soils with a "k" factor greater than 0.36 in a
watershed critical area; (ordinances)
3. Includes a pond or retention structure in a watershed critical area; (ordinances)
4. Will take place in tier 1 or tier 2 of a watershed critical area (ordinances)
The NC Sedimentation Pollution Control Act and the local sedimentation control ordinances
listed above all specify the following mandatory standards for land-disturbing activity:
1. Buffer Zone: A sufficient buffer zone must be retained or established along any natural
watercourse or lake to contain all visible sediment from the site in the first 25% of the
buffer strip nearest the disturbed area.
2. Graded Slopes and Fills:
State - the angle of cut-and-fill slopes must be no greater than that sufficient for proper
stabilization. Graded slopes must be planted with vegetation or otherwise stabilized
within 30 working days.
Ordinances - The angle for graded slopes and fills shall be no steeper than two (2) to one
(1) slope if they are to be stabilized with vegetative cover. Slopes or fills steeper than
two (2) to one (1) slope must be protected by structures. Graded slopes must be planted
with vegetation or otherwise stabilized within 30 working days.
3. Ground Cover: Off-site sedimentation must be prevented, and a ground cover sufficient
to prevent erosion must be provided within 30 working days or 120 calendar days after •
activity is completed, whichever is shorter.
4. Prior plan approval: An erosion and sedimentation control plan must be submitted at
least 30 days before land disturbance begins for any site larger than 1 acre.
Erosion and sedimentation control plays an important part in controlling nutrient loads,
particularly during construction. The ordinances are not credited with additional nutrient
reduction; rather they are a proactive step to help prevent nutrient loads greater than those
estimated from export coefficients.
On-site Wastewater Disposal
The counties within the watershed of the proposed Lake Randleman follow State standards for
on-site waste disposal. NC General Statutes, Chapter 130A Public Health, Article 11
Wastewater Systems, 333-343: governs the treatment and disposal of domestic-type sewage from
septic tank systems. Under NC law, an Improvement Permit or Construction Authorization must
be received from the local health department (i.e., Guilford, Forsyth, or Randolph Counties)
before a septic system can be installed. The local health department must evaluate the site to
determine if a permit could be issued.
3-24 Piedmont Triad Regional Water Authority f
Draft (February 1998) Section 3 - Nutrient Reduction Strategy
The site evaluation includes the following factors: topography and landscape position, soil
characteristics, soil wetness, soil depth, restrictive horizons, and available space. These factors
are classified as Suitable, Provisionally Suitable, and Unsuitable.
Sites are classified as:
Suitable - may be utilized for a septic system
Provisionally Suitable - may be utilized for a septic system, but have moderate limitations
Unsuitable - have severe limitations for the installation and use of a septic system
is
•
If all factors are classified the same, that classification will prevail. Where there is a variation in
classification of the criteria, the most limiting uncorrectable characteristics shall be used to
determine the overall site classification, as shown in Table 19.
Table 19. Factors Determining Suitability for Septic Systems
Factors Suitable Provisionally Unsuitable
Suitable
Topography (slope) < 15% 15%-30% >30%
Soil Characteristics
texture sandy, coarse loamy fine, loamy others
structure crumb and granular clayey platty, prismatic
clay mineralogy slightly expansive expansive
organic yes
Soil Wetness >48 in. below soil 36-48 in. below soil <36 in. below soil
surface surface surface
Soil Depth (to saprolite, >48 in. 36-48 in. <36 in.
rock, or parent material)
Restrictive Horizons >48 in. 36-48 in. <36 in.
(3 in. or more in
thickness)
Available Space based on square footage of nitrification field required for the long-term
acceptance rate
Location of septic systems is subject to a variety of restrictions. Specifically, every septic system
shall be located at least the minimum horizontal distance from the following:
1. any private water supply source, including any well or spring, 100 feet;
2. any public water supply source, 100 feet;
1 streams classified as WS-1 ,100 feet;
4. waters classified as SA, 100 feet from mean high water mark;
5. other coastal waters, 50 feet, from mean high water mark;
6. any other stream, canal, marsh, or other surface waters, 50 feet;
7. any Class I or Class II reservoir, 100 feet, from normal pool elevation;
8. any permanent storm water retention pond, 50 feet from flood pool elevation;
9. any other lake or pond, 50 feet, from normal pool elevation;
Piedmont Triad Regional Water Authority 3-25
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
10. any building foundation, 5 feet;
11. any basement, 15 feet;
12. any property line, 10 feet;
13. top of slope of embankments, 15 feet;
14. any water line, 10 feet;
15. drainage systems:
A. Interceptor drains, foundation drains, and storm water diversions
i. upslope, 10 feet
ii. sideslope, 15 feet
iii. downslope, 25 feet
B. Groundwater lowering ditches and devices, 25 feet
16. any swimming pool, 25 feet;
17. any other nitrification field, 20 feet
Regulation of on-site wastewater disposal plays an important part in controlling nutrient loads,
particularly in limiting the number of failing septic systems. Septic system failure rate is not
considered separately in the watershed model, and is not considered a major source at the whole-
watershed scale. The ordinances are not credited with additional nutrient reduction; rather they
are a proactive step to help prevent nutrient loads greater than those estimated from export
coefficients.
n
3.2.4 Education and Outreach Programs
PTRWA will work with its members and other jurisdictions in the watershed to conduct
education and outreach on the importance of public pollution prevention measures in helping to
achieve nutrient reduction goals in the Randleman Lake watershed. The general public is likely
to be unaware of the challenges associated with achieving the reduction goals and their role in
the process. The implementation plan will include developing information and presentation
materials that raise public awareness of the impacts of fertilizer runoff from commercial and
residential lawns and other common causes and sources of nutrient loading.
Existing means, such as conservation district outreach programs and Greensboro's storm water
management outreach program, will be used as a foundation for this strategy component.
Greensboro's public education component of its water conservation program won the U.S.
Environmental Protection Agency Region IV's first-place "Public Education" award in 1997,
and knowledge from that successful effort can be used to help design the public education
component for the Nutrient Reduction Strategy. PTRWA will provide information to the
existing outreach programs summarizing the goals of the Nutrient Reduction Strategy and the
responsibilities of the public in helping achieve the goals. Existing materials on best
management practices for commercial and home use of fertilizers can be used in this context.
•
3-26 Piedmont Triad Regional Water Authority
Draft (February 1998) Section 3 - Nutrient Reduction StrateU
3.2.5 Monitoring and Enforcement
• Monitoring and enforcement is an important part of the Nutrient Reduction Strategy. This
component helps ensure that the load reductions estimated in previous sections will actually be
achieved. All of the local watershed ordinances adopted to date include mechanisms to ensure
compliance with their site development standards. Each locality has designated an "Enforcement
Officer" or "Watershed Administrator" (typically the Town Manager or Planning Director) who
has responsibility for issuing permits pursuant to the locality's water supply watershed protection
ordinance. In these localities, all development plans within a water supply watershed are
reviewed by this individual, or by a designated review committee (the Planning Board, the Board
of Adjustment, or an appointed Watershed Review Board), prior to issuance of any building
permits. No building permit is issued unless the proposed development is found to be in
compliance with the locality's watershed protection ordinance. In the Randolph County
jurisdictions, the localities also review the development after construction is completed, and will
not issue an occupancy permit unless the development is found to meet all requirements of the
watershed protection ordinance. In those jurisdictions where High Density development is
allowed, the localities require approval of the required stormwater controls by a North Carolina
registered professional engineer (or, in the case of Kernersville, a landscape architect). Violators
of provisions of the watershed protection ordinances may also be subject to criminal and civil
penalties. In the case that a development is not approved, the developer may appeal this decision
to the designated review committee.
• The Development Ordinance of The City of High Point requires that development activities
which relate to zoning, subdivision and land use will be monitored and enforced by an
Enforcement Officer. The Enforcement Officer is responsible for issuing all permits required by
the Ordinance for development activity such as grading, building, land use, flood plain
development, erosion control, and others as required. Permit applications are submitted by the
property owner or his authorized agent and reviewed and processed by the Enforcement Officer
in accordance with the requirements of the Ordinance. Once development and/or land-disturbing
activity has begun, the Enforcement Officer will conduct periodic inspections and investigations.
The Enforcement Officer has the right upon presentation of proper credentials to enter on any
premises, public or private, at any reasonable hour, for the purpose of inspection and
determination of plan compliance. If a violation is found by the Enforcement Officer, the owner
or occupant is notified of the violation. The owner or occupant shall immediately remedy the
violation. If the owner or occupant fails to take prompt corrective action, the Enforcement
Officer will give the owner or occupant a written Notice of Violation indicating the following: 1)
that the land, building, structure or use is in violation of the Ordinance, 2) the nature of the
violation, and citation of the Section(s) of the Ordinance violated, and 3) the measures necessary
to remedy the violation.
3.3 Summary and Evaluation of Proposed Nutrient Reduction Strategies
This section summarizes the expected results of the proposed plan, including nutrient loads and
• BATHTUB model results and analysis of likelihood of meeting targets.
Piedmont Triad Regional Water Authority 3-27
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
3.3.1 Point Source Controls
For future conditions at buildout flow of 26 MGD, proposed reductions in effluent
concentrations from the High Point Eastside WWTP will provide a reduction of 50,880 kg/yr
total phosphorus (88%) from existing loads. An additional 910 kg/yr phosphorus will be
eliminated through connection of minor dischargers. Nitrogen loads from the WWTP under the
Nutrient Reduction Strategy will be reduced by 74,660 kg/yr (26%) from existing loads, while
nitrogen loads from minor dischargers will be reduced by 3,640 kg/yr.
3.3.2 Estimated Effectiveness of Nonpoint Source Control Strategies
Estimated reductions in nonpoint source nutrient loads associated with the proposed Nutrient
Reduction Strategy are primarily attributed to changes in predicted commercial and residential
density achieved under the water supply protection ordinances. Additional reductions are
achieved through increased use of agricultural BMPs, constructed wetlands and stormwater
controls. Figure 10 and Table 20 summarize the estimated nutrient loads by lake segment for
future conditions with the Nutrient Reduction Strategy in place..
Nonpoint source loads are expected to increase relative to existing conditions, due to increased
development, but this impact is mitigated by the Nutrient Reduction Strategy. In an average flow
12000
10000
Y 8000
c0
6000
to
2
O
t
N 4000
O
s
a.
2000
0

t out Ordinances

With S Or dinanc es

Ink Wnllnw, n an 1 Dapn 3A Mud 1 Dam
•

High Point Deep 2 Deep 3B Mud 2
Sub-watershed
Figure 10. Future Nonpoint Source Phosphorus Loads with and without Watershed
Protection Ordinances
•
3-25 Piedmont Triad Regional Water Authority
Draft (February 1998) Section 3 - Nutrient Reduction Strategy
•
•
•
Table 20. Estimated Nutrient Loads by Lake Segment (kg/yr) for Future Conditions,
with Nutrient Reduction Strategy,
WWTP at 0.2 mg/1 Total Phosphorus and 6 mg/1 Total Nitrogen
Segment Low Flow Year High Flow Year Average Flow Year
P N P N P N
Oak Hollow 3,780 34,830 10,690 103,320 6,980 69,250
City Lake 3,080 28,210 9,660 93,710 5,710 57,470
Deep River 1 (NPS and 4,120 34,040 11,870 111,950 8,110 76,470
minor PS)
Deep River 1 (WWTP, at 7,190 215,690 7,190 215,690 7,190 215,690
26 MGD)
Deep River 2 2,210 22,950 6,840 79,800 4,560 54,690
Deep River 3A 310 5,180 1,200 19,590 690 12,000
Deep River 3B 90 1,490 350 5,650 200 3,460
Muddy Creek 1 2,530 26,320 7,280 76,400 4,460 48,970
Muddy Creek 2 160 2,460 700 10,030 400 6,220
Near Dam 190 2,910 940 13,390 540 8,420
TOTAL 23,650 374,080 56,710 729,510 38,830 552,640
Total Nonpoint Source, 16,460 158,390 49,520 513,820 31,640 336,950
Future Conditions with
Nutrient Reduction
Strategy
Total Nonpoint, Existing 8,890 96,540 29,680 375,220 18,900 243,870
Conditions
Total Nonpoint, Future 22,990 203,470 61,720 589,150 39,640 386,190
Conditions without
Nutrient Reduction
Strategy
TOTAL, Existing 66,960 386,890 87,750 665,580 76,970 534,220
Conditions
TOTAL, Future 58,940 419,160 97,670 804,840 75,590 601,880
Conditions without
Nutrient Reduction
Strategy
Piedmont Triad Regional Water Authority
3-29
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
year, the proposed Nutrient Reduction Strategy is expected to result in a reduction of 8,000 kg/yr
(20%) total phosphorus loading from nonpoint sources versus future conditions without the •
strategy, and a reduction of 49,240 kg/yr (13%) in total nitrogen loading from nonpoint sources.
3.3.3 Net Load Reductions under Nutrient Reduction Strategy
As summarized in Table 20, combining the point and nonpoint load reductions for the proposed
nutrient strategy is expected to result in a reduction during an average flow year of 36,760 kg/yr
(49%) of total phosphorus compared to future conditions without the Nutrient Reduction
Strategy, and a reduction of 38,140 kg/yr (50%) versus existing conditions. For total nitrogen,
the proposed Nutrient Reduction Strategy is expected to result in a reduction of 49,240 kg/yr
(8%) of total nitrogen load versus future conditions without the Nutrient Reduction Strategy
(during an average flow year), although total loading will increase relative to existing conditions.
As techniques for additional nutrient removal at the WWTP prove feasible it will be possible to
further reduce nutrient loading levels toward the identified target loads.
For the upstream segments, the total phosphorus load to Deep River 1 with the WWTP at 26
MGD is approximately 15,300 kg/yr, while the load to Muddy Creek 1 is approximately 4,460
kg/yr for future land use and average flow conditions. Despite the reductions in load associated
with the Nutrient Reduction Strategy, these loads remain well in excess of the assimilative
capacities for phosphorus in these segments, estimated at 1,800 and 1,700 kg/yr, respectively.
Reaching the goal in Deep River 1 will only occur when the High Point Eastside WWTP effluent
can be reduced to 0.008-0.025 mg/1 total phosphorus. •
3.3.4 Estimated Chlorophyll a Response with Nutrient Reduction Strategies
Algal response is determined by the combination of nutrient loading and flow patterns. The
Nutrient Reduction Strategy results in a reduction in total nutrient loads, but also reduces dilution
flows by placing restrictions on impervious surface cover which promote direct runoff rather than
infiltration of rainfall.
Table 21 summarizes chlorophyll a predictions for future conditions with the Nutrient Reduction
Strategy in place, and can be compared to Table 8. (Note that there is no change in predicted
concentrations within Oak Hollow Lake and City Lake because water supply protection
ordinances are already in place for these reservoirs). At average and high flows, the Nutrient
Reduction Strategy results in a small decrease in predicted chlorophyll a concentrations in all
segments of the proposed Randleman Lake. For instance, at average flow the predicted
concentration in the Deep River 1 segment declines from 95 4g/1 under existing conditions and
80 µg/1 for future conditions without the Nutrient Reduction Strategy to 67 4g/l for future
conditions with the Nutrient Reduction Strategy.
•,
3-30 Piedmont Triad Regional Water Authority 1
Draft (February 1998) Section 3 - Nutrient Reduction Strategy
•
is

Table 21. Chlorophyll a Predictions for Future Conditions
with Nutrient Reduction Strategy and
WWTP at 26 MGD and 0.2 mg/1 Total Phosphorus
Lake Segment Low Flow Year High Flow Year Average Flow Year
(see Figure 3)
Chi a
(µg/1)
Nuisance
Frequency
Chl a
(µg/1)
Nuisance
Frequency
Chl a
(µg/1)
Nuisance
Frequency
Oak Hollow 15 2.5% 17 3.8% 17 3.4%
City Lake 22 9.1% 23 9.9% 23 10.4%
Deep River 1 81 83.0% 61 67.1% 67 73.3%
Deep River 2 32 24.3% 27 16.7% 29 19.0%
Deep River 3A 17 3.7% 17 3.5% 17 3.4%
Deep River 3B 12 0.9% 12 0.9% 12 0.9%
Muddy Crk 1 26 14.2% 26 15.5% 26 14.4%
Muddy Crk 2 12 0.8% 14 1.4% 13 1.0%
Near Dam 8 0.1% 12 0.7% 10 0.4%
Lake Randleman
Average 20 19 19
Piedmont Triad Regional Water Authority 3-31
Draft (February 1998) Section 4 - Implementation Plan
4. IMPLEMENTATION PLAN
PTRWA will work with its members to implement the Strategy, monitor progress and
effectiveness, and adapt Strategy-based management actions as needed to reach interim and long-
term nutrient reduction goals. The Authority will track overall implementation of the Strategy,
including but not limited to the following methods and responsibilities for implementation.
4.1 Schedule for Implementation
•
Section 3 of this document outlines management actions to reduce existing nutrient loads and
mitigate nutrient loading impacts associated with future growth. The schedule for implementing
these measures is detailed in Table 22.
Table 22. Schedule for Implementation of Management Actions
Description of Management Proposed Schedule
Action
Set up PTRWA management Establish plan administration within 6 months of EMC plan
plan administration approval
Establish PTRWA data Refine monitoring plan (e.g., perform reconnaissance; establish
collection, information specific sampling sites, flow measurement methods, field and
management, and assessment laboratory methods) and assessment methods (e.g., determine how
protocols and means annual nutrient loading estimates will be calculated, and relate to
data collection), within 12 months of EMC plan approval
? Establish interlocal agreements between PTRWA and local
jurisdictions to share residential and commercial development
information and land use data, within 12-18 months of EMC plan
approval
? Establish information management system to quality assure, store,
share, assess, and present data, within 12-18 months of EMC plan
approval
Implement PTRWA ? Baseline monitoring prior to impoundment of reservoir
monitoring program Full monitoring program after reservoir impounded
Reduce High Point Eastside Facility renovation expected by July, 2001; PTRWA will also work
WWTP effluent TP with High Point to have the interlocal agreement providing financial
concentration to < 0.2 mg/1 incentives in place by July, 2001
Complete construction of 6 To be completed prior to filling of the reservoir area
wetlands projects to filter
water in these drainage areas
Reevaluate Nutrient Within 3-5 years of filling of the reservoir, and every 5 years
Reduction Strategy and thereafter coordinated with DWQ's 5-year management cycle for the
Implementation Plan Cape Fear River Basin
•
Piedmont Triad Regional Water Authority 4-1
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
In addition to management actions detailed in Section 3, Table 22 includes the proposed schedule
for implementation of the administrative structure and monitoring program, and for reevaluation M
of the overall Nutrient Reduction Strategy and Implementation Plan. PTRWA will be
responsible for tracking progress in adhering to the schedule.
4.2 Monitoring Program
PTRWA will establish a monitoring program to track implementation of strategies and evaluate
their effectiveness.
4.2.1 Tracking Implementation Activities
Monitoring programmatic indicators of plan implementation will help PTWRA ensure that
proposed actions are followed through with, and provide the Authority with information that is
key to analyzing the effectiveness of management actions. Programmatic indicators to be
tracked by PTRWA are listed in Table 23.
Table 23. Proposed Programmatic Indicators to Track Plan Implementation
Description of Programmatic Indicator Source of Tracking Information
Milestone dates for Plan administration setup PTRWA
(e.g., date information management system for
plan implementation tracking is in place)
Date enhanced treatment process completed for City of High Point
High Point Eastside WWTP
Date interlocal agreement between City of High PTRWA
Point and PTRWA is in place providing financial
incentive to meet 0.2 mg/l total phosphorus goal
in Eastside WWTP effluent
Dates projects are completed (constructed PTRWA contractors
wetlands, regional stormwater ponds)
Date by which all local ordinances for water Local jurisdictions within watershed,
supply watershed protection are in place; Dates of summarized by PTRWA
revisions to water supply watershed protection
ordinances by individual jurisdictions
Dates environmental monitoring is performed PTRWA
Annual progress reports PTRWA
Dates of strategy and plan reevaluation and PTRWA
amendment
•
W
4_2 Piedmont Triad Regional Water Authority f
Draft (February 1998) Section 4 - Implementation Plan
4.2.2 Tracking Environmental Effectiveness
• Monitoring environmental impacts of plan implementation will allow PTRWA to gauge overall
effectiveness of the Nutrient Reduction Strategy and Implementation Plan. Environmental
indicators to be tracked by PTRWA are listed in Table 24.
is
Table 24. Proposed Environmental Indicators to Track Plan Implementation
Description of Environmental Indicator Source of Tracking Information
Annual Point Source TP and TN Loads Facility monitoring data [assuming permission
can be received to gain onsite access, small
domestic facilities will be periodically sampled
by PTRWA]
Annual Nonpoint Source TP and TN Loads Local jurisdictions report new residential and
commercial development information
including area of project, density, impervious
surface area, type of land use/land cover
project is replacing, and BMP details
including SW detention
? Local health departments report new onsite
septic systems and existing systems that are
failing
? NRCS and conservation district data on BNIP
implementation, animal operations and
cropping
Tributary Water Quality PTRWA monitoring program (see details below)
? Total Phosphorus, Orthophosphate, Total
Inorganic Nitrogen, Total Organic Nitrogen
[concentrations and loading]
Lake Water Quality PTRWA monitoring program (see details below)
? Total Phosphorus, Orthophosphate, Total
Inorganic Nitrogen, Total Organic Nitrogen,
Chlorophyll a, Temperature, pH, Secchi
Depth, Dissolved Oxygen
Downstream Deep River Water Quality PTRWA monitoring program (see details below)
? Total Phosphorus, Orthophosphate, Total
Inorganic Nitrogen, Total Organic Nitrogen
[concentrations and loading]
Although PTRWA will be responsible for conducting the instream monitoring program, the
Authority will depend heavily on its local jurisdiction members to report changes in land
use/land cover from development. Local jurisdictions, therefore, will be responsible for tracking
and reporting this information in a timely manner and in a format that follows protocols for
Piedmont Triad Regional Water Authority 4-3
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
information management and quality assurance/quality control (QA/QC). PTRWA will pursue
interlocal agreements with local government jurisdictions to ensure commitment to this process.
In addition, PTRWA will coordinate with other agencies to facilitate data exchange. Key sources
of information will include the Division of Water Quality NPDES discharge monitoring data,
local health department septic system data, and NRCS and Conservation District data on
agricultural best management practices being used within the watershed.
Tributary and Downstream Deep River Sampling Program
Tributary monitoring data will be needed to help estimate nutrient loading being delivered to
Randleman Lake. Proposed monitoring sites include each of the significant tributaries, including
(see Figure 11 for approximate locations):
1. Bull Run at mouth
2. Deep River above confluence with Bull Run
3. Richland Creek upstream of WWTP outfall*
4. Reddicks Creek at mouth
5. Hickory Creek at mouth
6. Muddy Creek at mouth
[* Coordination with DWQ and High Point Eastside is needed to ensure adequate effluent
nutrient monitoring data are collected to provide accurate annual point source loading estimates
for the Richland Creek subwatershed.] is
Monitoring downstream of the Randleman Lake dam will be conducted to support calculations of
nutrients trapped in the lake on an annual basis. Figure 11 indicates an approximate station
location for:
7. Deep River below Randleman Lake dam and above Randleman WWTP outfall
PTRWA plans to conduct year round monitoring at the tributary and downstream monitoring
locations, with a minimum of monthly sampling. Sampling will performed such that a range of
flows are captured, including base and high flow conditions. In addition to the parameters listed
in the indicator table, flow will be measured so that phosphorus and nitrogen loads can be
estimated. PTRWA anticipates using a combination of grab samples and some selected
composite sampling over high-flow events. Specifics of the monitoring program will be worked
out during the first 12 months following EMC approval of the overall Nutrient Reduction
Strategy and implementation plan.
Lake Sampling Program
Monitoring lake sites will be critical to evaluating the effectiveness of nutrient loading
management strategies. One station will be located in the upper Deep River segment of the lake,
which is expected to be the most heavily impacted by nutrient loads. Monitoring in the
0
4-4 Piedmont Triad Regional Water Authority
Draft (January 1995) Section 4 - Implementation Plan
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,
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-? ? LANE

Approximate location of LUCLINAM
proposed lake monitoring sites
Figure 11. Locations of Proposed Monitoring Sites
Piedmont Triad Regional Water Authority 45
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
upper segment of the Muddy Creek arm will provide information on the most sensitive area of '
that tributary. A third station will be located near the water supply intake to monitor quality in
the lower section of the lake and in an area of high interest given the lake's intended drinking
water use. In summary, the proposed lake sites for monitoring include (see Figure 11 for
approximate locations):
A. Deep River Segment 1
B. Muddy Creek Segment 1
C. Deep River Segment 3B near intake
Lake sampling will be performed monthly during the growing season, May through October, of
each year. Depth integrated samples over a distance of twice the secchi depth from the surface
will be collected for chemical analyses. Temperature, pH, and dissolved oxygen will be recorded
at 1-3 meter intervals.
Sampling Quality Assurance/Quality Control
All samples will be collected and processed using standard operating procedures and quality
assurance protocols consistent with monitoring conducted by the North Carolina Division of
Water Quality.
4.3 Data Management
PTRWA will develop and maintain computerized data bases to track all programmatic and •
environmental indicator results. A meta-data file on all data coverages will be maintained.
PTRWA members will be advised regarding formats and protocols for transferring data, and will
be responsible for adhering to QA/QC and other protocols.
4.4 Evaluating and Updating Strategy and Implementation Plan
Annual evaluations will be conducted by PTRWA to determine progress made in implementing
the plan and achieving strategy goals. An annual progress report will be prepared for the
Authority's Board, and copied to DWQ within 3-6 months of the end of each calendar year. The
report will include estimates of point and nonpoint source loadings for the previous year, and
summaries of tributary and inlake water quality conditions. In each succeeding year, the reports
will include comparisons to loading rates and water quality conditions from previous years'
monitoring.
The PTRWA Board will be responsible for periodically updating the Nutrient Reduction Strategy
and Implementation Plan. The first update is scheduled for 3-5 years from the date of
impoundment of Randleman Lake. PTRWA anticipates that the new reservoir will take at least
2-3 years to stabilize with regard to water quality, based on reviewing study results from other
large impoundments in the Piedmont area. Therefore, the Authority will need to be careful not to
place too much emphasis on the intake water quality monitoring data during those first 2-3 years * i
4-6 Piedmont Triad Regional WaterAuthority
Draft (February 1998) Section 4 - Implementation Plan
when evaluating effectiveness of the initial plan. A decision on a more specific due date for the
plan update will not be determined until after the first 2-3 years of data have been analyzed and
40 evaluated.
•
Piedmont Triad Regional Water Authority 4-7
Draft (February 1998) References
• 5. REFERENCES
Black & Veatch. 1990. Water Quality and Quantity Studies to Support Randleman Lake
Environmental Impact Statement, December 1, 1990. Prepared for Piedmont Triad Regional
Water Authority, Greensboro, NC.
Borden, R.C., J.L. Dorn, J.B. Stillman, and S.K. Liehr. 1996. Evaluation of Ponds and Wetlands
for Protection of Public Water Supplies. Report submitted to Water Resources Research Institute
of the University of North Carolina, Raleigh, NC.
Butcher, J., T. Clements, A. Beach, K. Brewer, D. Korn, N. Archambault, P. Kellar and G.
Pesacreta. 1995. Falls Lake Watershed Study, Final report. Prepared for The North Carolina
Department of Environment, Health, and Natural Resources. The Cadmus Group, Durham, NC.
Davis-Martin-Powell & Associates. 1996.
CDM. 1989. Watershed Management Study: Oak Hollow and City Lake Watersheds. Report to
City of High Point and Guilford County, N.C. Camp Dresser & McKee, Raleigh, NC.
NCDEM. 1994. Water Quality Monitoring Data for Waters in the Upper Deep River Area, July
28, 1992 - October 7, 1993. North Carolina Division of Environmental Management, Water
Quality Section, Environmental Sciences Branch, Raleigh, NC.
NCDWQ. 1996. Cape Fear River Basinwide Water Quality Management Plan. North Carolina
Division of Water Quality, Water Quality Section, Raleigh, NC.
Novotny, V. and H. Olem. 1994. Water Quality: Prevention, Identification, and Management of
Diffuse Pollution. Van Nostrand Reinhold, New York.
Schueler, T.R., P.A. Kumble, and M.A. Heraty. 1992. A Current Assessment of Urban Best
Management Practices: Techniques for Reducing Non-Point Source Pollution in the Coastal
Zone. Metropolitan Washington Council of Governments, Washington, DC.
Tetra Tech. 1997. Randleman Lake Project: Water Quality Considerations for the Siting and
Design of a Drinking Water Treatment Plant, Phase II Report. Tetra Tech, Inc., Research
Triangle Park, NC.
Walker, W.W., Jr. 1987. Empirical Methods for Predicting Eutrophication in Impoundments.
Report 4-Phase III: Applications Manual. U.S. Army Corps of Engineers Technical
Report E-81-9. U.S. Army Waterways Experiment Station, Environmental Laboratory,
Vicksburg, MS.
0 Piedmont Triad Regional Water Authority 5-1
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
Walker, W.W., Jr. 1985. Empirical Methods for Predicting Eutrophication in Impoundments.
Report 3-Phase II: Model Refinements. U.S. Army Corps of Engineers Technical
Report E-81-9. U.S. Army Waterways Experiment Station, Environmental Laboratory,
Vicksburg, MS.
WPCF. 1990. Natural Systems for Wastewater Treatment. Manual of Practice FD-16. Water
Pollution Control Federation, Alexandria, VA.
E
?f
5-2 Piedmont Triad Regional Water Authority
Draft (February 1998) Appendix 1
APPENDIX I. EXISTING POINT SOURCE NUTRIENT LOADS
High Point Eastside WWTP
Existing discharge from the High Point Eastside WWTP is assumed to average 10.5 MGD, with
an average phosphorus concentration of 4 mg/1, based on monthly monitoring data collected from
January 1986 through December 1989 (Black & Veatch 1990). This is consistent with results
from monthly effluent monitoring data for May 1996 through May 1997, which has an average
of 3.98 mg/l total phosphorus.
Black & Veatch (1990) reported an average total nitrogen concentration in the effluent of 23 mg/l
from 1986-1989. For the May 1996-May 1997 period, concentrations of total nitrogen varied
from 9 to 42 mg/1, with an average of 19.6 mg/l. Average concentration in the effluent was thus
assumed to be approximately 20 mg/l total N.
The specification of nutrient chemical form is also an important factor in water quality
simulation, since it helps determine the availability of nutrients to algae and the rate of
sedimentation losses. Information on phosphorus speciation in the High Point Eastside effluent
is not available, but it is unlikely that the phosphorus is 100% orthophosphate, and some
conversion to organic forms by bacteria and plankton is expected within the stream reach
between the discharge point and the proposed lake pool. Based on recent experience with
Durham dischargers and analysis of phosphorus species reported by NCDEM (1994) for 1992-93
at station RL4, in Deep River just below the WWTP discharge, an estimate of 75 percent
orthophosphate in the WWTP effluent (as delivered to the proposed lake) appears reasonable.
For nitrogen, it was assumed that approximately 85% of the load would be in inorganic form,
based on analysis of performance monitoring of the Durham Northside WWTP (Butcher et al.
1995).
Existing `Domestic-type "Dischargers
As of July 1, 1997 there were a total of 12 "domestic type" permitted discharges of treated
wastewater within the Randleman Lake watershed, of which 9 were actively discharging to the
watershed downstream of the Oak Hollow and High Point Lake watersheds (letter from W. C.
Basinger, NC Division of Water Quality Winston-Salem to Andrea Spangler, Piedmont Triad
Water Authority, November 19, 1997). These facilities discharge treated sewage, and thus
constitute an additional source of nutrient loading. There are two "domestic type" permitted
dischargers of treated wastewater above Oak Hollow Lake. Current status of these dischargers is
shown in Table A-1.
In addition to the domestic-type dischargers, there are 13 permitted small industrial dischargers
in the watershed. Most of these permits are for stormwater and non-contact process water, and
include 11 permits for stormwater flow from the tank farm on the East Fork of Deep River. The
40
Piedmont Triad Regional Water Authority A4-1
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
Table A-1. Domestic Type Dischargers in Randleman Lake Watershed
Discharger NPDES Location Status
Permit
Discharges to the direct drainage of proposed Randleman Lake
Hickory Run MHP NC- UT Bull Run Operating; permitted flow 0.035
0041505 Creek
Sumner Elementary NC- UT Hickory Operating; permitted flow 0.009 MGD
School 0037117 Creek
Plaza MHP NC- UT Hickory permitted flow 0.003 MGD
0041483 Creek
Crown MHP NC- UT Hickory Operating; permitted flow 0.05 MGD
0055255 Creek
Southern Guilford NC- UT Hickory Operating; permitted flow 0.012 MGD
High School 0038229 Creek
Southern Elementary NC- UT Hickory Operating; permitted flow 0.0075 MGD
School 0038091 Creek
Penman Heights NC- Taylor Br. of Operating; permitted flow 0.025 MGD
(Rayco Utilities) 0055191 Muddy Creek
Hidden Forest MHP NC- UT Deep River Operating; permitted flow 0.10 MGD
0065358
Rimmer Mobile NC- Muddy Creek Permitted for 0.0204 MGD, but never
Home Court 0069451 constructed.
Melbille Heights NC- Muddy Creek Operating; permitted flow 0.0315 MGD
(Rayco Utilities) 0050792
Discharges to Oak Hollow Lake watershed
Slate Residence NCG- UT W Fork Operating; permitted flow 0.00045 MGD
550102 Deep River
Sandy Ridge NC- UT W. Fork Operating; permitted flow 0.0175 MGD
Correctional Center 0027758 Deep River
Total Permitted Flow 0.029 MGD
A
0
•
A-I-2 Piedmont Triad Regional Water Authority
Draft (February 1998) Appendix I
other two permitted discharges are AMF Hatteras Yachts (NCG-500204), discharging to a
tributary of Richland Creek with a permitted flow of 0.002 MGD; and LCP National Plastics
(NC-0036366) discharging to a tributary of West Fork Deep River above Oak Hollow Lake. The
Hatteras Yachts discharge will be discontinued as the plant is moving out of the basin. None of
these industrial discharges contains a significant nutrient load.
The total permitted flow from operating domestic-type dischargers appears to be 0.029 MGD
While these sources contain nutrients, their combined load is insignificant compared to the
current 10.5 MGD flow from High Point Eastside WWTP. These small discharges are of little
importance in terms of the overall nutrient balance of Randleman Lake, but do have the potential
to present localized problems.
0
40
Piedmont Triad Regional Water Authority A-I-3
Draft (February 1998) Appendix 11
APPENDIX II. ESTIMATION OF FUTURE LAND USE CONDITIONS
Developing a Nutrient Reduction Strategy requires a reasonable estimate of future changes in
land use patterns within the watershed. Future land use cannot be predicted with certainty;
however a reasonable estimate can be obtained by analysis of growth-shaping factors.
Future land use within any given area of the watershed will be largely determined by the
interaction of four factors: (1) demand or development pressure; (2) water supply protection
ordinances which limit the types of development permissible; (3) infrastructure, including
availability of roads, water, and sewer; and (4) natural characteristics of soils and slopes.
Future demand is one of the most difficult factors to evaluate. For this study we have based
estimates of future land use demand on year 2025 trendline scenario developed for the Piedmont
Triad Regional Transportation study. This study identifies projected living and working areas,
and represents the best available consensus information on future land use demand. We assumed
that the 2025 projected living and working areas represent areas of high demand, while areas not
so identified are areas of low demand. For the high-demand areas it was assumed that the land
would be developed to 90% of the capacity allowed by the applicable water supply protection
ordinances and natural environmental constraints, with the "living" areas converting to residential
development and the "working" areas converting to commercial, office, light industrial, or
institutional uses. For the lower demand areas it was assumed that there would be an
approximately 20% increase in the existing number of housing units, reflecting the general rate
of population increase expected for the Piedmont-Triad area.
The methods used to estimate future land use differed by county, according to the type and
format of data which were available. For Guilford Co., detailed coverages of a variety of
growth-shaping factors were obtained in a Geographic Information System (GIS). The Guilford
Co. portions of the watershed contain most of the expected high growth areas and are most
critical for the Nutrient Reduction Strategy, and a detailed geographically-based estimate of
future land use was constructed using the GIS. For Randolph and Forsyth counties, only limited
data (primarily zoning) were obtained in GIS format, and a simpler method of analysis was
applied.
For the high-growth portions of Guilford Co. the estimates of future land use involved the
following steps:
1. Account for existing high-intensity land uses grand-fathered under water supply
protection ordinances.
2. Account for publicly owned land and other preserved open space.
3. Determine relevant future jurisdiction, based on the annexation agreement established by
High Point, Archdale and Jamestown extra-territorial jurisdictions, and planned sewer
expansion by Greensboro.
Piedmont Triad Regional Water Authority A-II-1
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
4. Determine whether an area is now or will be sewered. Projections of future sewered areas
within Guilford Co. are given by the Guilford Co. Atlas "Forecast 2015" and the water
and sanitary systems improvement map for the High Point Southeast Economic
Development Area (April, 1996). Jamestown's entire extra-territorial jurisdiction is also
assumed to be sewered in the future. Existing and future sewered areas, along with the
occurrence of poor soils for onsite wastewater disposal, are shown in Figure A-1.
5. For sewered high-growth areas, assume 90% development by 2025, in either residential
or commercial land uses, subject to water supply protection ordinances of the relevant
jurisdiction. For residential areas in the high-growth area, new lots are assumed to be
created in the minimum specified zoning size class allowed under the ordinances. Actual
lot yield per acre is based on the assumption used by Guilford Co. Planning that 25% of a
developed area is typically required for roads, other utilities, high slopes, and other
characteristics of a site which increase effective lot size. Thus development under 1 acre
zoning is assumed to achieve an effective lot size of 1 dwelling unit per 1.25 acres.
6. For unsewered areas, 90% development is also assumed for high growth areas. However,
effective lot size and potential yield of dwelling units is potentially limited by soil
qualities. For unsewered areas with soils with poor qualities for onsite wastewater
disposal it is assumed that the minimum effective lot size is 5 acres per dwelling unit,
even if zoning allows denser development.
For areas in Guilford Co. without substantial development pressure, the potential future land use
is assumed to represent a mix of 60% forest, 10% crop, 10% pasture, and 20% residential use.
The residential land uses are distributed across a range of lot sizes, with half in the minimum
allowed lot size.
The transfer matrix showing the calculation of potential land use distribution in response to
growth shaping factors is shown in Table A-2. Once potential land use is estimated it is
combined with existing land use information to create an estimate of future land use. This
procedure allows existing higher-density land uses, as well as commercial and institutional land
uses in residential areas, to be retained for the future land use scenario.
In the absence of water supply protection ordinances, it is assumed that all areas with high
development pressure would be sewered and 90% developed. High growth residential areas are
then assumed to achieve a mix of 70% 0.25-0.5 acre single family lots and 30%
townhouse/apartment development. High growth commercial areas are assumed to achieve a
mix of 50% commercial/office, 10% open space, 20% heavy industry, and 10% institutional land
use.
Outside of Guilford Co., GIS coverages were available for zoning and 2025 "living" and
"working" areas; however, other growth-shaping factors were not available in GIS, requiring a
different approach. For the Forsyth Co. portion of Oak Hollow watershed, the CDM (1989)
analysis under Scenario lA was used. For Randolph and Forsyth counties, future land use is
based primarily on zoning and an assumption that approximately 50% of the soils have poor
A-II-2 Piedmont Triad Regional Water Authority
Draft (February 1998) Appendix 11
characteristics for onsite wastewater disposal (the same ratio observed in southwestern Guilford
Co.) For Randolph Co. it is assumed that sewer extension under water supply ordinances will be
confined to the extra-territorial jurisdiction limits of Archdale, Randleman, and Kernersville.
Finally, in all low-growth areas of Randolph and Forsyth counties it is assumed that future land
uses represent a 20% increase in number of housing units, with some limited outlying
commercial development to support the increased population. The housing unit baseline is
drawn from 1990 US Census data. New lots created in these areas are distributed across a
variety of lot sizes. Future land use is then estimated based on existing land use, modified by
transferring land area from rural (forest, agriculture) land uses to residential land uses.
0
0
Piedmont Triad Regional Water Authority A-II-3
Randleman Lake Nutrient Reduction Strategy and Implementation Plan Draft (February 1998)
Legend
County Boundaries
f'+'I Randleman Lake Watershed
Poor Development Soils
Existing Severed Areas
Proposed Sewer Areas
1 0 1 2 3 4 5 Mles
Figure A-1. Sewered Areas and Soils with Poor Suitability for Onsite Wastewater Disposal
in the Guilford County Portion of the Randleman Lake Watershed
A-11-4 Piedmont Triad Regional Water Authority
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Section 2
Response to NC DWQ Comments
Draft Nutrient Reduction Strategy for
Randleman Lake
March 19, 1998
•
HAZENAND SVAT
Draft Nutrient Reduction Strategy for Randleman Lake
Response to NC DWQ Comments
Piedmont Triad Regional Water Authority
March 19, 1998
On February 6, 1998, the Piedmont Triad Regional Water Authority (PTRWA)
submitted to the North Carolina Department of Environment and Natural Resources,
Division of Water Quality (DWQ) a Draft Nutrient Reduction Strategy and
Implementation Plan for the proposed Randleman Lake. The DWQ provided oral
comments on the draft at a meeting held in Raleigh on March 2, 1998. Additional
written comments were provided by letter from Coleen Sullins, Acting Chief, Water
Quality Section, with attachments, dated March 9, 1998. This document and
attachments provide a detailed response to each of the DWQ's comments.
The comments and concerns raised by the DWQ were uniformly constructive and
appropriate. PTRWA has addressed each of these comments below. Incorporation of
these comments and additional material will result in a revised and improved Nutrient
Reduction Strategy, which will be submitted to the DWQ and the NC Environmental
Management Commission (EMC).
The letter of March 9, 1998 from the DWQ raised four major areas of concern:
• Measures for reduction of nonpoint nutrient loads,
• Option of removing High Point Eastside Wastewater Treatment Plant
effluent,
• Wetlands mitigation, and
• Toxic organic chemicals
A fifth major concern, existing excursions of the fecal coliform bacteria standard in the
upper Deep River, was brought forth at the March 2, 1998 meeting. Each of these five
major concerns is discussed in detail below, with reference to several. attachments
which contain supporting technical documentation. Item 6 of this response addresses
the 12 "additional staff comments" which were attached to the March 9 letter from the
DWQ.
1. MEASURES FOR REDUCTION OF NONPOINT NUTRIENT LOADS
The draft Nutrient Reduction Strategy prepared by PTRWA outlines a variety of
measures to be undertaken by the Authority and local jurisdictions to reduce present
and future point and nonpoint loading of nutrients to Randleman Lake. The DWQ
commented, however, that the Nutrient Reduction Strategy "did not sufficiently address
the reduction of nutrients," and stated "that the Plan appeared to offer no new potential
initiatives or measures to address nonpoint sources of nutrients over what is being
required by existing regulatory requirements."
Randleman Lake Nutrient Reduction Strategy: Response to Comments
Piedmont Triad Regional Water Authority March 20, 1998
In fact, the draft Nutrient Reduction Strategy proposed initiatives which are well in
• excess of regulatory requirements for the proposed WS-IV classification of the
reservoir. The impression that no measures beyond the regulatory minimum were
proposed is mistaken, and likely reflects insufficient clarity in the draft Strategy
document.
C]
•
Comparison to State Minimum Requirements. The draft Nutrient Reduction
Strategy proposes initiatives which are well in excess of regulatory requirements for the
proposed WS-IV classification of the reservoir. Ways in which the proposed strategy
goes beyond state minimum regulatory requirements are highlighted in Table 1.
Table 1. Comparison to State Minimum Requirements
State Requirements Ways in Which Nutrient Reduction
Strategy Goes Beyond State
Requirements
Point Source Controls
High Point Eastside WWTP to reduce total PTRWA will provide performance incentives
phosphorus in effluent to 0.5 mg/I. for WWTP to achieve a 0.2 mg/I total P
concentration. This measure alone results in
an 80% reduction in the P load to the lake.
Watershed Classification
State expected to give Randleman Lake a Randolph County and Randleman have
WS-IV classification. given watershed a WS-III classification,
which requires stricter restrictions on
allowable development density, dischargers,
and new landfills allowed. Randolph and
Guildford Counties enacted watershed
protection standards more than 10 years
ago.
Watershed Overlay Districts
State defines two overlay districts for a WS- Guilford County jurisdictions further
IV watershed: Critical Area and Protected subdivide Critical Area into 4 "Tiers" with
Area. additional restrictions on development.
Critical Area defined as 1/z mile and draining Significant portions of Critical Area go
to reservoir. beyond/2 mile from reservoir.
Protected Area defined as 5 miles and Protected Area defined as entire Balance of
draining to reservoir. Watershed, applies watershed restrictions
beyond 5 miles from reservoir.
2 Randleman Lake Project Phase 11 Report
Piedmont Triad Regional Water Authorih, March 20, 1998
•
ICJ
n
LJ
Table 1. Comparison to State Minimum Requirements
State Requirements Ways in Which Nutrient Reduction
Strategy Goes Beyond State
Requirements
Prohibited Uses
WS-IV Critical Area: no new landfills or sites Guilford County jurisdictions prohibit a long
for land application of sludge. list of additional uses in the Critical Area
(e.g., mining and quarrying, fuel oil sales,
truck washing).
WS-IV Protected Area: no land uses are In Randolph County and Randleman, no
specifically prohibited. new discharging landfills are allowed in the
Balance of the Watershed.
Limits to Development Intensity
Critical Area, low-density option, residential In Guilford Co. jurisdictions: no development
development up to 2 dwelling units per acre in Tier 1, 1 du/5 ac in Tier 2. In areas
(du/ac) allowed. without public sewer, Tier 3 is limited to 1
du/3 ac and Tier 4 to 1 du/1 ac.
In Randolph Co. jurisdictions: 1 du/2 ac.
Critical Area, low density option, non- In Guilford Co. jurisdictions: no development
residential development up to 24% built- in Tier 1, Tier 2 limited to 2.4-2.5 %; unless
upon area allowed. public sewer is present Tier 3 is limited to 4
% and Tier 4 limited to 12 %.
In Randolph Co. jurisdictions: limit is 6-12

Critical Area, high-density option: up to 50 % In Guilford Co. jurisdictions: No high-density
built-upon area allowed. development allowed in Tiers 1 and 2.
Option available in Tiers 3 and 4 only with
public sewer, with limits of 34 % and 40 %
built-upon area, respectively.
In Randolph Co. jurisdictions: High-density
option not allowed.
Protected Area, low-density option: up to 2 Guilford Co., High Point direct drainage, and
du/ac allowed. Randolph Co. jurisdictions allow only 1 du/ac
for balance of watershed, unless public
sewer is available.
Protected Area, high-density option: up to No high density option allowed in Randolph
70% built-upon area allowed. Co. jurisdictions or Forsyth Co.
Randleman Lake Nutrient Reduction Strategy: Response to Comments
Piedmont Triad Regional Water Anthorin, March 20. 1998
•
•
•
Table 1. Comparison to State Minimum Requirements
State Requirements Ways in Which Nutrient Reduction
Strategy Goes Beyond State
Requirements
Stormwater Control Requirements
Stormwater controls required only in High Guilford County jurisdictions (Guilford
Density development. County, Greensboro, High Point,
Jamestown) also require stormwater controls
in some or all Low Density development in
the Critical Area.
Additionally, the Guilford County jurisdictions
require stormwater controls in Low Density
development in the Balance of the
Watershed if the site is marginal or the
development plan is not sufficiently
protective of adjoining waters.
Stream Buffer Requirements
Stream buffers required around perennial 30'-50' buffers on perennial waters in new
streams in new developments: 30-foot for Low Density development.
new Low Density development, 100-foot
buffer for new High Density development. Buffer around lakes is 100' in Randolph
County ordinances and 200' in Guilford
County jurisdictions (Tier 1). PTRWA is
acquiring a 200' buffer around Randleman
Reservoir.
High Point and Jamestown provide
protection for open drainage channels in
addition to perennial waters.
Regional Stormwater Retention Ponds
Not required. 5 ponds, controlling over 17,000 acres of
drainage.
Constructed Wetlands
Not required for water quality purposes; may 6 constructed wetlands, controlling
be required for mitigation. approximately 28,000 acres of drainage.
Monitoring and Assessment
Not required Detailed plan for regular monitoring, data
management, and continuing assessment.
Randleman Lake Project Phase II Report
Piedmont Triad Regional Water Authority March 20, 1998

C
2. ANALYSIS OF OPTIONS CONSIDERED BUT NOT INCLUDED IN NUTRIENT REDUCTION
STRATEGY
2.1 Analysis of Option of Removing High Point Eastside Effluent
The DWQ requested an updated analysis of the economics of the option of removing
the High Point Eastside WWTP effluent from the lake. This would be accomplished by
piping the discharge from the existing WWTP to a point just below Randleman. Cost
estimates for this option were developed by Hazen and Sawyer, P.C. It was assumed
that a 78 MGD firm pumping capacity would be required to handle peak flows, and that
a 66-inch diameter forcemain 72,000 feet in length would be required to reach the
discharge point. In addition, because of the long transit time between the WWTP and
discharge point, effluent reaeration would be required. Estimated capital costs are in
excess of $28,000,000 for this option, as shown in Table 2.
Table 2. Capital Cost of Effluent Bypass around Randleman Lake
Item Cost
Effluent Pumping Station: 78 mgd firm capacity $3,600,000
Forcemain: 66-inch diameter, 72,000 feet $19,008,000
Effluent Reaeration Facility $200,000
Outfall Diffuser $240,000
SUBTOTAL $23,048,000
Engineering and Contingencies @ 25% $5,762,000
TOTAL CAPITAL COST $28,810,000
In addition to incurring a high capital cost, rerouting the High Point effluent below
Randleman has important water quality implications for the Deep River. The 1996
Cape Fear River Basinwide Water Quality Management Plan states that elevated
nutrient levels are present throughout the upper Deep River, while "the lower Deep
River studies indicate that water quality in the study reach, including the Carbonton
impoundment, is severely impacted by nutrient loading from upstream sources." With
Randleman Lake in place, approximately 80% of the total phosphorus load generated
above Randleman Dam would be trapped in the lake, resulting in a marked decrease in
loads to the lower Deep River. In contrast, moving the effluent below Randleman
would place the major load source nearer to the nutrient-impacted reaches of the lower
Deeper River and could potentially increase downstream impacts. Discharge of the
Eastside WWTP into the lake will result in increased eutrophication of the lake,
particularly in those sections of lake closest to the discharge point. However,
elimination of the point source has no significant impact on water quality at the
is proposed intake location.
Randleman Lake Nutrient Reduction Strategy: Response to Comments 5
Piedmont Triad Regional Water Authority March 20, 1998
It should also be noted that removal of the effluent would still not result in predicted
algal concentrations in the Deep River 1 segment reaching target levels. Under
average flow and future land use conditions, the predicted average chlorophyll a
concentration in this segment would be 46 pg/I with a 48% probability of concentrations
greater than 40 pg/l. For average flow and existing land use, the predicted average
chlorophyll a concentration would be 39 pg/I, with a 38% probability of concentrations
greater than 40 pg/I.
2.2 Enhanced Stream Buffers
Stream buffers were not assigned a water quality benefit in modeling to date.
Buffers, with widths currently specified in regulations, can provide significant
nutrient removal for new development if designed and maintained for this
purpose.
Stream buffers are instituted for a number of reasons. Important among these are flood
protection, maintenance of drainage ways, reduction of streambank erosion, and
prevention of incursion of buildings and private roads into riparian areas. Stream
buffers can also provide water quality benefits; however, reduction of nutrient loads by
stream buffers is largely dependent on proper design and management of the buffer.
In the previous version of the Nutrient Reduction Strategy, no quantitative reduction in
nutrient loads was assigned to stream buffers, on the assumption that the buffers
specified in the existing regulations might not be specifically maintained for water
quality purposes. As an additional component of the Nutrient Reduction Strategy
enhanced water quality stream buffers could be required for all new development.
These enhanced buffers would be designed to maximize potential nutrient removal.
The most promising type of buffers for urban streams combine a grass strip in the outer
(landward zone) with mature forested buffer toward the stream (Schueler, 1995).
[??7
Buffers can remove a significant fraction of nutrients passing through them in shallow
sheet flow. This removal occurs through deposition of particulate matter and uptake by
plants. However, flow which is "concentrated" into ephemeral channels is not
effectively treated, but tends to flow through buffers with minimal removal. As a general
rule of thumb, flow from pervious areas may be regarded as concentrated, and thus not
effectively treated by buffers, when it arises from a distance of more than 150 feet
beyond the buffer edge (Schueler, 1995). This limits the total effectiveness of buffers
in reducing nonpoint nutrient loads from a watershed.
A typical water shed in the eastern United States has approximately 1.4 miles of
perennial streams per square mile. For instance, with a 50 foot stream buffer on both
sides of perennial channels, the total watershed area enclosed within the buffers and
within 150 feet of the buffer boundaries accounts for approximately 10.6% of the
watershed area, and only this fraction is controlled by the buffers. For the Randleman
6 Randleman Lake Project Phase 11 Report
Piedmont Triad Regional Water Authority March 20, 1998
Lake watershed, the stream density is greater than average, and the area controlled by
buffers is thus larger. Using a GIS analysis of perennial streams shown in 1:24,000
scale hydrography, 50 foot stream buffers in the Randleman Lake watershed would
control 12.8% of the land area. 1 w 7 1
It is assumed that buffers maintained for water quality improvement purposes would be
placed primarily on perennial streams. While some of the jurisdictions in the watershed
also have requirements for buffers on intermittent streams or drainage ways, the
purpose of these narrow buffers is primarily to provide adequate drainage and reduce
flooding. Specifying large buffers with specific vegetative practices onJntermitten-t
usCrz
r1
4mc
streams would introduce severe constraints on use of property. Water quality benefi .s,
of buffers on intermittent _streams_are. also not well.demonstrated. Therefore, only
buffers on perennial streams are considered to provide ?a quantitative water quality
benefit in this analysis. 0",5 i y w`{
Removal efficiencies of properly maintained buffers vary widely, ranging from 0 to
100% of influent pollutant load in agricultural studies. Removal efficiencies are likely
highest in relatively low gradient rural areas with low imperviousness and well-drained
w CA,

soils. Rates of nutrient removal by stream buffers within the Coastal Plain portion of ---
the Neuse River basin (NCDWQ, 1996) are thus likely overly optimistic for the cJ co,su(?
Piedmont setting of the Randleman Lake watershed. Accordingly, we have used the"A')
fitted trend of removal efficiency in response to buffer width reported by Desbonnet et O+?
al. (1994; cited in Schueler, 1995). Estimated rates of phosphorus and nitrogen S?
removal from watersheds with stream buffers are summarized in Table 3 for several
different buffer widths, based on GIS analysis of 1:24,000 hydrography data obtained
from the N.C. Center for Geographic Information Analysis.
Table 3. Estimated Nutrient Removal Rates for Stream Buffers
Buffer Width (ft) Percent of
watershed area
controlled Total P removal
(percent) from
controlled area Total P removal
(fraction) from
total watershed Total N removal
(percent) from
controlled area Total N removal
(fraction) from
total watershed
30 12.8% 55% 0.070 60% 0.077
50 14.2% 60% 0.085 65% 0.092
100 17.6% 68% 0.120 70% 0.123
150 21.1 % 70% 0.148 72% 0.152
•
It is generally difficult to add effective water quality stream buffers to areas which are
already developed. Therefore, a water quality benefit for stream buffers is assumed
only for loads from new development. For instance, if 50 foot buffers are assumed for
the Muddy Creek 1 sub-watershed, the water quality benefits of buffers on new
development are estimated to result in a reduction of approximately 650 kg/yr of total
phosphorus and 5,600 kg/yr of total nitrogen for future conditions with other
components of the Nutrient Reduction Strategy in place. Extending buffer width to 100
Randleman Lake Nutrient Reduction Strategy: Response to Comments 7
Piedmont Triad Regional Water Authority March 20, 1998
feet would provide an increase to 920 kg/yr total phosphorus and 7,470 kg/yr total
nitrogen for this basin. Using the widths specified in existing regulations (30 feet in
Guilford and Forsyth jurisdictions, 50 feet in Randolph County jurisdictions) the
estimated removal rates for the entire Randleman Lake watershed under future
conditions with the Nutrient Reduction Strategy in place are 2,850 kg/yr total
phosphorus and 25,220 kg/yr total nitrogen.
•
•
Reductions in load for a variety of buffer widths are summarized in Table 4. Note that
doubling width results in a much smaller gain in load removal.
Because removal rate estimates for buffers are based on long-term average
performance, it is appropriate to apply this estimated reduction to the long-term
average load generated within a sub-watershed. That is, the load reduction is applied
to the average load prior to the calculation of specific loads adjusted for high, average,
and low flow years. In this way, the load reduction attributed to buffers also varies in
accordance with annual flow.
Table 4. Estimated Nutrient Load Reductions from Application of Water Quality
Stream Buffers to New Development
Total Phosphorus
Reduction (kg/yr) Total Nitrogen
Reduction
(kg/yr)
For Entire Randleman Lake Watershed
Existing Buffer Width (30' in Guilford and
Forsyth, 50' in Randolph Co.) 2,850 25,220
All 50' Buffer 3,280 28,880
All 100' Buffer 4,600 38,530
All 150' Buffer 5,520 46,190
For Deep River 1 Segment
Existing 30' Buffer 440 3,810
50' Buffer 530 4,570
100' Buffer 750 6,100
150' Buffer 890 7,320
For Muddy Creek 1 Segment
Existing 50' Buffer 650 5,600
8 Randleman Lake Project Phase H Report
Piedmont Triad Regional Water Authority March 20, 1998
•
r
100' Buffer 920 7,470
150' Buffer 1,100 8,950
Cost estimates for additional land acquisition for buffers were developed by Hazen &
Sawyer, P.C. Buffer widths were multiplied by estimated perennial stream length to
estimate area; the area of a 30-foot buffer was subtracted from this number to estimate
additional land to be acquired. Cost of acquisition was derived by multiplying the
additional land area by per acre cost. It was assumed that 50% of acquired land would
require reforestation at a cost of $400 per acre. Total cost is summarized in Table 5. +
Table 5. Capital Cost of Additionatiqnd Acquisition for Buffers
Additional Area Required by Buffer Expansion (Acres)
50-ft buffer width 100-ft buffer
width 150-ft buffer
width
Deep River Segment 1 118 414 710
Muddy River Segment 1 71 249 427
Additional Estimated Cost
Deep River Segment 1
(@ $5,000 per acre) $590,000 $2,070,000 $3,550,000
Muddy River Segment 1
(@ $3,500 per acre) $248,500 $871,500 $1,494,500
Reforestation Cost (50%
of area @ $400 per
acre) $37,800 $132,600 $227,400
Total Cost $876,300 $3,074,100 $5,271,900
2.3 On-site Stormwater Control
At present, none of the jurisdictions have regulations specifying on-site stormwater
control for low density development (except for Guilford Co. within the Critical Area). At
the small development scale, stormwater control is most likely to be through Extended
Detention or Dry ponds with infiltration. The record of such controls in reducing
nutrient loads leaving a site is mixed. However, they may have an important secondary
effect through control of runoff peaks.
In the existing modeling we have assumed that a watershed delivery ratio reduction in
loads could not be justified for denser development (residential lots of 1 acre or less,
Randleman Lake Nutrient Reduction Strategy Response to Comments 9
Piedmont Triad Regional Water Authorin, March 20, 1998
commercial and industrial development) located within highly developed portions of the
watershed. The rationale behind this is that such areas would produce rapid peak
runoff from impervious areas which would transport nutrients quickly to the lake-unlike
runoff from more rural, pervious areas where the hydrograph peak is less sharp and
significant losses are expected, on average, in transport between source and basin
outlet. This is a highly conservative assumption, which likely leads to some over-
estimation of loads to the lake. The effects of this conservative assumption is most
noticeable in the Muddy Creek 1 watershed, where rapid development from existing
fairly rural conditions is predicted. Here we have both an increase in load generation
due to shift from forest to residential land use, AND a large increase in load delivery
due to a shift from rural to urban conditions and consequent assumption of no delivery
ratio reduction. Thus, the predicted impacts of development in this watershed are
amplified by an assumption of greater delivery.
If on-site stormwater control was required for new developments this would result in
hydrologic response more like existing "natural" conditions. It would then be
appropriate to apply a watershed delivery ratio reduction to loads generated by these
areas (although not to existing high density uses if retrofitting requirements are not
assumed). In the Muddy Creek 1 basin this would result in an estimated reduction of
phosphorus loading of greater than 1000 kg per year under average flow. Significant
(although less dramatic) reductions in loading would also be predicted for the Deep
River 1 and Deep River 2 watersheds. Preliminary results for Deep River 1 and Muddy
Creek 1 are shown in Table 6.
Table 6. Estimated Phosphorus Load Reductions with On-site Stormwater
Control (kg/yr)
Low Flow Year Average Flow Year High Flow Year
Deep River 1 760 1,380 2,050
Muddy Creek 1 660 1,080 1,880
In sum, a valuable option to consider for "extra effort" would be a requirement that new
developments under the low-density option with residential lots of 1 acre or less in size
and new commercial and industrial developments provide on-site control of the first 1/2"
of rainfall. This would be similar to Guilford County's existing requirements for the
Critical Area and for developments in the Balance of Watershed which do not score
100 or more on the subdevelopment review criteria. The cost of this option would be
passed on to the developer. However, representatives of High Point and Randolph II
County have indicated that they are unwilling to amend their ordinances to include this l t
requirement at this time.
•
10 Randleman Lake Project Phase 11 Report
Piedmont Triad Regional Water Authority' March 20, 1998
0 2.4 Additional Regional Stormwater Impoundments and Constructed Wetlands
Constructed wetlands considered for mitigation in the Randleman Lake watershed are
expected to provide only a minor water quality benefit because of low surface area to
drainage area ratios. There are apparently very few additional sites suitable for
mitigation wetlands available within the watershed.
Regional stormwater impoundments provide the potential for effective removal of large
quantities of nutrients; however, here too sites are limited. A major problem is that the
best sites for impoundments tend to be those already selected for wetlands mitigation.
Also, the impoundments may themselves create additional mitigation needs.
The analysis of regional stormwater impoundments has not yet been completed,
although preliminary information has been provided by Davis Martin and Powell (DMP).
Three sites appear worth considering as allowing the necessary configuration to
provide adequate performance and removal of sediment and phosphorus:
Richland Creek (Deep River 1 drainage). This pond has an estimated surface
area of 43 acres, an average depth of 4 feet, and an approximate drainage area of
9900 acres. It would control about 70% of the drainage from the highly-developed High
Point portion of this sub-watershed. Based on the surface area to drainage area ratio,
this impoundment may be estimated to achieve approximately 65% removal of influent
phosphorus on an annual basis (Driscoll, 1988). A major problem with this site is that it
would pre-empt a major wetlands mitigation area.
Upper Muddy Creek (Muddy Creek 1 drainage). According to information
provided by DMP, this site would have an estimated surface area of 9.75 acres, an
average depth of 4 feet, and a drainage area of 4800 acres. It appears that this site
would also pre-empt a wetlands mitigation site. According to the figures supplied by
DMP, this impoundment would control about 83% of the drainage from the highly-
developed portion of the Muddy Creek 1 drainage. Estimated phosphorus removal rate
is about 52%, due to relatively small surface area (Driscoll, 1988).
Lower Muddy Creek (Muddy Creek 1 drainage). The pond would have a surface
area of 4.7 acres and a drainage area of about 9500 acres (about 72% of the sub-
watershed). Due to the small surface area of this impoundment relative to drainage
area, phosphorus removal efficiency would be low (about 20%).
Preliminary estimates of potential phosphorus load reduction associated with these
impoundments is shown in Table 7. Note that the Richland Creek site would also incur
a small gain in load relative to the current Nutrient Reduction Strategy due to the
elimination of the wetland at the same site. A similar situation may apply for the Muddy
Creek 1 site.
E
Randleman Lake Nutrient Reduction Strategy: Response to Comments 11
Piedmont Triad Regional Water Authority March 20, 1998
•
Table 7. Estimated Phosphorus Load Reductions with Regional Stormwater
Impoundments (kg/yr)
Low Flow Year Average Flow Year High Flow Year
Richland Creek 1,670 3,300 4,820
(Deep River 1)
Upper Muddy 660 1,170 1,900
Creek
(Muddy Creek 1)
Lower Muddy 340 610 990
Creek
(Muddy Creek 1)
The Richland Creek and Upper Muddy Creek sites are not considered viable options
because they preempt wetlands mitigation sites required by DWQ and the U.S. Army
Corps of Engineers. Preliminary engineering studies of the Lower Muddy Creek site
have not been undertaken. Based on the actual construction cost of past regional
detention ponds by the City of High Point (Davis and Piedmont Lakes), it is expected
that individual stormwater impoundments will cost on the order of $2-3 million each.
Site characteristics such as topography and drainage would affect individual
development costs. Detailed studies would be required to assess these factors.
The DWQ Water Quality Section suggested that more than 121 acres of wetland
restoration be located "to provide some margin of error if the selected mitigation sites
are not successful." Another comment suggested "additional nonpoint source controls
such as creating additional wetlands beyond that required through the 401 process."
PTRWA is committed to obtaining appropriate wetland mitigation sites for the proposed
Randleman Lake. Unfortunately, potential wetland sites which meet the DWQ
requirements are rare within the basin's hilly topography, and considerable effort has
been required to identify sufficient sites to meet the 121 acre requirement.
PTRWA's consultant Davis Martin Powell and Associates originally identified nine
potential wetland sites located on various tributaries of the proposed Randleman Lake.
Following site visits by DWQ personnel and review by Pete Colewell (DWQ Wetlands
Group), four of these sites were eliminated for a variety of reasons including, but not
limited to, unsuitable topography, existing wetlands, and location. Since that time,
PTRWA has sought additional potential mitigation sites to increase the area of wetland
restoration. Two additional sites (near the Kersey Valley Landfill and south of Oakdale
Cotton Mill) are currently under investigation for suitability.
40
12 Randleman Lake Project Phase 11 Report
Piedmont Triad Regional Water Authority March 20, 1998
is PTRWA will continue to attempt to identify additional potential wetlands mitigation sites
consistent with Wetland Restoration Program Basinwide Restoration Goals. Additional
:sites would both add a margin of safety on meeting 401 requirements and provide
water quality benefits through trapping of nutrients and sediment. Given the
topography of the watershed it appears, however, that it will be difficult to achieve a
substantial increase beyond the requirement for 121 acres in wetlands which are
consistent with Program criteria.
The need for wetlands mitigation also interacts with the analysis of additional options
for nutrient control. One potentially effective way of controlling nutrient loads from the
already urbanized areas of High Point and Archdale would be through installation of
regional stormwater detention ponds on Richland Creek and Muddy Creek. These
have a much better track record of removing nutrients than wetlands of the type and
size that are proposed. Like wetlands, suitable sites for ponds are limited by
topography, as the pond must have sufficient surface area and volume for effective
control, yet should not be more than 4 or 5 feet deep to prevent the development of
stratification and anoxia. Unfortunately, the sites suitable for regional detention ponds
are the same ones best suited for wetlands mitigation, so it may not be feasible to
satisfy the wetlands mitigation objective if additional nutrient loading through regional
detention ponds is pursued.
PTRWA agrees that monitoring for success of the mitigation wetlands will be important.
Indeed, such monitoring will be required as part of the 404 process.
3. TOXIC ORGANIC CHEMICALS (SEE ALSO ATTACHED MEMORANDUM)
The DWQ raised several questions regarding potential loading of toxic organic
chemicals to the proposed reservoir and impacts on reservoir water quality. Important
areas of concern identified by DWQ include chemicals present in ground water at the
Seaboard Chemical and Riverdale Landfill sites, and phenols of undetermined origin
detected during 1997 sampling.
To address these and various other issues related to toxic organic chemicals, Tetra
Tech developed a fate and transport model of the proposed lake and assessed the
likely range of chemical concentrations throughout all lake segments. This analysis
indicates that neither toxics from Seaboard Chemical/Riverdale Landfill or phenols are
likely to result in unacceptable water quality conditions within the proposed reservoir.
The technical analysis is provided in the attached separate memorandum, which also
addresses lindane concentrations identified in the High Point Eastside WWTP effluent
and "unidentified peaks" reported in the DWQ water quality analyses for organic
chemicals.
•
Randleman Lake Nutrient Reduction Strategy: Response to Comments 13
Piedmont Triad Regional Water Authoritv March 20, 1998
Seaboard Chemical/Riverdale Landfill. Ground water beneath these sites
contains a large variety of organic solvents. Despite their presence in ground water,
the DWQ sampling of Richland Creek and Deep River has not detected any excursions
of North Carolina water quality standards or EPA ambient water quality criteria.
Remedial investigations of the Seaboard Chemical and Riverdale Landfill sites are
ongoing. Construction of the proposed reservoir will not flood the contaminated sites,
but will decrease the hydraulic gradient and rate of flow of ground water from these
sites to the reservoir. Construction of the reservoir is also expected to result in further
diminution of concentrations due to increased dilution volume, increased time of travel,
and increased opportunity for loss to volatilization, settling, photolysis, hydrolysis, and
biodegradation, depending on the characteristics of individual chemicals.
A conservative screening analysis was used to estimate an upper bound on potential
in-lake concentrations of chemicals derived from these sites. The screening analysis
used the maximum observed concentration in ground water of each of ten chemicals of
concern, coupled with the maximum expected rate of ground water discharge from the
site suggested by the NC Division of Solid Waste. Even with these conservative
assumptions, maximum predicted in-lake concentrations of all chemicals of concern
was at least an order of magnitude less than the relevant standard or criterion. Ratios
of maximum predicted in-lake concentrations to water quality standards range from
Ol 0.05 to 0.000009.
Phenols. Relatively high concentrations of phenolic compounds were observed
at a number of locations in the Deep River during 1997 sampling. Concentrations were
often in excess of the North Carolina WS standard of "not greater than 1 fag/I (phenols)
to protect water supplies from taste and odor problems due to chlorinated phenols;
specific phenolic compounds may be given a different limit if it is demonstrated not to
cause taste and odor problems, and not to be detrimental to other best usage." Both
the sources and the specific chemical identity of the phenolic compounds detected by
the DWQ are unknown. However, the samples were also analyzed by gas
chromatography, including a Method 625 scan for individual chlorophenols and
nitrophenols. None of these specific compounds was detected above EPA criteria, and
most were non-detect.
Analysis with the lake fate and transport model indicates that concentrations of total
phenolics are likely to be less than the water quality standard within most sections of
the lake. There is, however, a potential for concentrations of total phenolics in excess
of the 1 pg/l standard in the immediate vicinity of sources only. Because the North
Carolina standard is only applicable to taste and odor problems associated with
chlorinated phenols, and because these chlorinated phenols were not detected at
problem levels in the DWQ sampling, these localized problems should not present an
excursion of water quality standards.
•
14 Randleman Lake Project Phase 11 Report
Piedmont Triad Regional Water AuthoriA, March 20, 1998
0 4. FECAL COLIFORM BACTERIA (SEE ALSO ATTACHED MEMORANDUM)
During both 1993 and 1997 sampling, concentrations of fecal coliform bacteria were
noted in excess of state standards within streams in the area of the proposed lake.
Highest concentrations were seen in Muddy Creek and in Deep River below Muddy
Creek, and are likely associated with animal operations in that area. Lower
concentrations were seen upstream in the High Point area, likely reflecting urban
runoff.
As with toxic organic chemicals, concentrations of fecal coliform bacteria are expected
to decline relative to observed stream concentrations once the lake is built, even with
existing loads. This is because increased residence times in the lake will provide a
greater opportunity for natural die-off of enteric bacteria. A screening analysis (see
attached memorandum) suggests that existing loads will not result in excursions of
water quality standards on a lake segment average basis, with most concentrations
less than 100 organisms per 100 ml. In addition, mitigation measures are expected to
significantly decrease coliform loading prior to impoundment of the reservoir.
There are presently five dairies in the reservoir, but none of these yet has the Waste
Management Plan required by NC regulations approved. The owners of these dairies
have applied for a Special Agreement in accordance with Senate Bill 1217, which
10 allows the EMC to enter into a special agreement with an operator who registered by
September 1, 1996 with their local Soil and Water Conservation District office and who
makes a good faith effort to obtain an approved animal waste management plan by the
December 31, 1997 deadline. Two dairies (Green Valley Farm, draining to Deep River,
and Cashatt Dairy, draining to Muddy Creek) still have active pasture land within the
future reservoir buffer which will be purchased by PTRWA following completion of
negotiations and removed from use prior to impoundment. Implementation of required
Waste Management Plans and removal of pasture land within the reservoir buffer will
result in decreased bacterial loads. A variety of additional mitigation measures are
proposed which are expected to result in significant reductions in loading of fecal
coliform bacteria and consequent further reductions in concentrations. Status of waste
management planning for the five regulated dairies is summarized from information
contained in the Applications for Special Agreement in Table 9.

Randleman Lake Nutrient Reduction Strategy: Response to Comments 15
Piedmont Triad Regional Water Authoritv March 20, 1998
U
0
•
Table 9. Status of Dairy Waste Management Plans
Facility Average Animal Acres for Improvements and Proposed
Population Land Schedule for Remaining Work
Application
of Waste
Green Valley Farms, 250 head milking, -600 Irrigation system, fencing, cattle
Keith S. Hockett, 1001 200 heifers and calves crossing/trails, buffers,
Hockett Dairy Rd., on pasture waterways, and diversions
Randleman, NC 27317 installed.
Waste handling equipment
(3/98)
Waste storage structure (11/98)
Runoff controls from exterior
lots (11/98)
Cashatt Dairy 150-200 head milking 350 Deadline for filing information
Davis Cashatt week of 3/23.
5665 Davis Country
Rd.
Randleman, NC 27317
Buttke Dairy 1200 head milking 800 Vegetation removed on dam.
James D. Mitchell Jr. 800 head calves and Land application site (5/98)
5796 Walker Mill Rd. heifers Start pump markers (6/98)
Randleman, NC 27317 Waste management retrofit
(10/98)
Run off controls (10/98)
Land application handling
equipment (10/98)
Loflin Dairy 300 head 170 Runoff control for exterior lots
Clifford Loflin (12/98)
2410 Loftin Dairy Rd. Waste storage structures
Sophia, NC 27350 (12/98)
Waste application site (12/98)
Waste handling equipment
(12/98)
W.R. Farlow & Sons 175 head milking 300 Deadline for filing information
William R. Farlow 125 replacement week of 3/23.
409 Aldridge Rd. heifers
High Point, NC 27263
5. ADDITIONAL COMMENTS
A number of "additional staff comments" were attached to the letter from the DWQ.
Each of these twelve numbered comments has been addressed or will be addressed in
the revision to the Nutrient Reduction Strategy.
16
Randleman Lake Project Phase H Report
Piedmont Triad Regional Water Authority March 20. 1998
5.1 Confidence intervals on chlorophyll a predictions will be included in the
revised strategy. PTRWA's consultant, Tetra Tech, has also developed
an improved methodology for estimating the percent of days with
concentrations greater than 40 pg/I, based on the temporal variability
seen in intensive monitoring on Falls Lake rather than BATHTUB default
values. (This improved methodology will change the numbers, but not
result in any qualitative difference in the general results.) Confidence
intervals on percent exceedence predictions can present a difficult
statistical problem; however, approximate confidence intervals on these
figures are also being developed for the revised Strategy.
5.2 Additional documentation is being assembled for the load reduction
estimates. Language will also be clarified as to percent reductions. The
existing text is confusing, as many different conditions and scenarios are
being compared.
Future land use projections for the study were based on data elicited from
local governments and planners as part of the Piedmont Triad Regional
Transportation Study and provided to us by Paul Kron, Piedmont Triad
Regional Council of Governments (personal communication to Jonathan
Butcher, Tetra Tech, 12/10/1997). This is the best estimate of future
• growth which was available at the time of the study, and no other detailed
geographically-based projections of future land use have been completed
for the study area. The Regional Transportation Study will not be
completed and published for another 8 months or more. Because the
land use projections are not in a final form, the nutrient analysis makes
the very conservative assumption that all areas identified as growth areas
in the study will be 90% built out by the year 2025. The Implementation
Plan calls for continued data management and periodic assessment. If
more precise future growth projections become available they will be
incorporated into the analysis.
5.3 The description of state minimum requirements for control of stormwater
on p. 3-18 will be corrected to incorporate the appropriate language.
5.4 The Penman Heights subdivision wastewater effluent was included in
modeling of current conditions. Of the two minor dischargers to Upper
Muddy Creek, only Melbille Heights is presently considered to be feasible
for connection to public sewer. Under the Nutrient Reduction Strategy,
Melbille Heights will be connected to the High Point wastewater system.
Appropriate clarification will be inserted in the text.
5.5 Cost/economic analyses to compare methods of reducing nutrient load
were requested. A cost-benefit analysis for the major alternative of re-
Randleman Lake Nutrient Reduction Strategy: Response to Comments 17
Piedmont Triad Regional Water Authority March 20, 1998
• routing High Point Eastside WWTP effluent below the dam has now been
developed and will be added to the Nutrient Reduction Strategy (see item
2 above). For various other structural controls cost comparisons have not
been supplied because selection of options is not sensitive to cost. For
nutrient removal at the WWTP the proposed reductions are at the level
safely achievable by currently available technology, and additional
expenditure would not necessarily guarantee further reduction. Wetlands
and regional stormwater detention ponds are limited primarily by
availability of suitable sites, rather than cost. The ability to construct
regional stormwater detention ponds is limited by necessity to achieve an
absolute goal of wetland mitigation acres. Finally, non-structural control
options for reducing nutrient load, such as additional zoning restrictions,
involve many cost externalities and a variety of impacts on stakeholder
groups which are not meaningful to compare solely on a cost basis.
5.6 PTRWA agrees that nutrient management plans are desirable for all
animal operations in the watershed, although PTRWA and local
jurisdictions have limited authority to require them for small operations not
covered by existing regulations. PTRWA recognizes that the existing
documentation of animal operations in the watershed is incomplete, and
are working to correct this. The five large dairies in the watershed subject
0 to State regulations have all submitted initial Waste Management Plan
information but have not yet received certified animal Waste Management
Plans under the requirements of 15A NCAC 2H .0200. A Special
Agreement delaying final certification was issued to each of these dairies
by DWQ on 2/11/1998. Within the near future each of these dairies
should have in place a certified Waste Management Plan which will help
to minimize impacts on the lake. These are discussed above under Item
5. A sixth small dairy is located in the reservoir critical area which does
not fall under State animal waste regulations. PTRWA anticipates
acquisition of this dairy, although negotiations are not complete.
5.7 The wording change suggested for p. 1-1 is appropriate and will be
incorporated into the revised version of the Strategy. PTRWA is
developing this strategy "for consideration by the DWQ and the EMC."
5.8 A detailed study was conducted on the performance and nutrient removal
capacities of two of the four existing High Point regional stormwater
ponds by scientists at NC State. The final version of this document was
recently published by WRRI (Borden, R.C., J.L. Dorn, J.B. Stillman. and
S.K. Liehr, 1997, "Evaluation of Wet Ponds for Protection of Public Water
Supplies", UNC-WRRI-97-311) and confirms the reduction efficiencies
i
18 Randleman Lake Project Phase H Report
Piedmont Triad Regional Water Authorih, March 20, 1998
• used in the modeling. PTRWA will provide additional discussion and an
updated citation in the revised Strategy.
5.9 The comment regarding concentrated versus "diffuse" stormwater
drainage is correct. The intent of this sentence is merely to say that most
stormwater in the area is not via piped conveyances. PTRWA will correct
the inappropriate language in the revised Strategy.
5.10 Imprecise statements regarding the NC Sedimentation and Pollution
Control Act of 1973 will be rectified.
5.11 On page ES-2 of the draft Strategy, the Total Phosphorus Reduction Goal
for a High Flow Year, Upper Segment of Deep River Lake arm, is
incorrectly given as 63,860 kg/yr. The correct number is 63,270 kg/yr.
Other calculations on page ES-2 are correct. On page 2-10 the loading
capacity for the Deep River 1 segment was erroneously transcribed as
2,800 kg/yr total phosphorus. The correct number is 2,880 kg/yr.
5.12 The incorrect description of the WS-V classification (which is not directly
relevant to this study) will be corrected.
0
•
Randleman Lake Nutrient Reduction Strategy: Response to Comments 19
?J
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CA
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•
Section 3
Analysis of Potential Water Quality for Toxic
Organic Chemicals in the Proposed
Randleman Lake
TetraTech, Inc.
March 18, 1998
•

HAZENAND SAWYER
•
•
TMO
Analysis of Potential Water Quality for Toxic Organic
Chemicals in the Proposed Randleman Lake
Prepared for Piedmont Triad Regional Water Authority
Tetra Tech, Inc.
March 18, 1998
Potential concentrations of toxic organic chemicals within the proposed Randleman Lake are of
concern for classification of the waterbody and protection of the water supply. In a few
instances, NC DWQ monitoring in the Deep River has revealed concentrations of organic
chemicals in excess of state standards or EPA criteria. Solvents are also present in ground water
beneath the former Seaboard Chemical solvent recovery facility and High Point landfill near the
confluence of Richland Creek and Deep River, which may discharge to surface water.
From the EIS, subsequent comments on the EIS, and recent DWQ investigations there appear to
be four areas of concern for toxic organic chemicals in the proposed Randleman Lake:
• Concentrations of lindane in High Point WWTP effluent
• Potential leaching of solvents from the Seaboard/landfill site. Detected toxicants are:
chlorobenzene, 1,2-dichloroethane, 1,1-dichloroethylene„ vinyl chloride, benzene, 2-
chlorophenol, methylene chloride, 1,1,2,2-tetrachloethane, 1,1,2-trichloroethane, and
toluene.
• Concentrations of phenolics, apparently from a variety of sources in the Deep River
watershed
• Presence of unidentified organic chemicals in DWQ monitoring of the Deep River
drainage
Each of these areas of concern is addressed below. Following analysis, none of these concerns
appears to represent a threat to the requested WS-IV classification of the reservoir.
1. Modeling Framework
While small loads of a variety of organic chemicals are likely to be present in runoff and WWTP
effluent from any urban area, construction of the reservoir will drastically change the hydrology,
and the concentrations expected in the reservoir cannot be inferred directly from concentrations
currently observed in streams or ground water. Accordingly, a modeling approach is required to
estimate the expected concentrations once the reservoir is constructed.
Both the WWTP and ground water discharge from the solvent recovery/landfill site are likely to
load organic chemicals to surface water on an intermittent basis; however, a conservative worst-
case estimate of potential impact can be made by assuming that pollutant mass is loaded at a
steady rate using a conservative upper bound estimate, then calculating the resulting
concentration at the water intake using a simple steady-state model of transport through the lake.
Randleman Lake Toxic Chemicals Analysis 1
Tetra Tech, Inc.
March 18, 1998
The underlying hydraulics (on a seasonal average basis) are provided by the application of the
BATHTUB eutrophication model, as discussed in the Nutrient Reduction Strategy and
accompanying modeling report. In addition, it is necessary to consider a variety of fate and
transport processes that will affect concentrations of lindane (as well as other organic chemicals
contained in the WWTP effluent) at the water intake. These processes include:
• Sorption to particulate matter;
• Volatilization to the atmosphere;
• Settling of the particulate fraction to the lake bottom;
• Resuspension from the lake bottom;
• Deep burial and sequestration of the pollutant within lake sediments;
• Degradation within the water column; and
• Degradation within the sediments.
These processes are numerous and complex. For initial assessment of the magnitude of risk,
however, it is appropriate to employ a steady-state model of lake fate and transport that includes
all the major processes, but in a simplified form. This model, based largely on the work of
Chapra (1991), is described below.
Assuming that a chemical is completely mixed throughout the volume, V, of a lake segment, i,
and exchange with the next downstream segment occurs only by advection, a mass balance of the
total chemical mass contained in the water column of the lake segment may be written as
dc.
where c is concentration (M/L3), t is time (T), Q is flow (L3/T), W is mass loading rate (M/T), v,
is net reaction and exchange loss rate per unit area basis (L/T), and A is segment surface area
(L2).
At steady state, dc/dt = 0 and (11) may be solved for c:
W.
ci = (2)
vtr ``l
or, dividing the top and bottom of (12) by A;,
c. = W. (3)
A;(qs; + v;;)
where qs = Q/A is segment overflow rate (L/T). This is the classic solution for toxicant
concentration in a mixed lake of Thomann and Di Toro (1983) and is similar to the lake mass
balance equation for total phosphorus presented by Vollenweider (1969). If W is expressed in
µg/yr, A in mz, and qs and v, in units of m/yr, Equation (3) yields c in µg/m3, equivalent to
nanograms per liter (ng/1).
2 Randleman Lake Project Phase 11 Report
Tetra Tech, Inc. March 18, 1998
Equation (3) yields concentrations in a lake segment adjacent to the source of loading. The
is analysis must also address transport through downstream lake segments. This may be
accomplished as follows: Consider the case where the mass loading to segment i is derived from
the next upstream lake segment, numbered i+l. Mass loaded to segment i is then equal to that
advected out of segment i+1:
W. = Qr+1• ci+I (4)
Substituting (3) into (4) yields
W+1 Qi+1 qsi+I
W. = = W1.+1 (5)
A;+I (gs;+1 +vti+l) qsi+I + vti+,
For pollutant loads proceeding through a series of lake segments to a terminal segment, the
concentration in that terminal segment, c,, can be written as the product of the reduction
occurring in all upstream segments:
__ 1 • 1 r, q,, W
CI AI(gsl + vtl) ii=2 qsi + vti m (6)
where m is the total number of lake segments and W,,, is the mass loading to the upstream
segment.
Equation (6) represents net loss of chemical mass during transport through the generalized loss
coefficient v,;. Total loss rate v, can be separated into dissolved phase loss (decay and
volatilization) and losses due to sediment interaction. Following Chapra (1991), the sediment
interaction can be expressed in terms of a recycle ratio, Fr':
vi = kl zl + vv fdI + (1-Fr t) • (vs fP1 + Vd fll) (7)
where k, is a first-order decay rate (total mass basis) in water column (1/T), including photolysis,
hydrolysis, and biodegradation, such that k, = Ln(2)/half-life; z, is segment depth (L); v,, is a
volatilization coefficient (LIT); fd, is the dissolved fraction in the water column, equal to
1/(1+Kdm); v, is the settling velocity, (L/T); fp, is the particulate fraction in water column, equal
to 1 - fdI; vd is a diffusion mass transfer coefficient (LIT); Kd is a partition coefficient (L3/M); and
m is the suspended solids concentration (MV).
The volatilization velocity, v,,, can be estimated using the two-film model (Mackay, 1981) by
1 _ 1 1
VV Kl Kg H
where Kt is the liquid side mass transfer coefficient (LIT), Kg is the gas side mass transfer
• coefficient (LIT), and H, is the dimensionless form of the Henry's Law constant. Mills et al.
Randleman Lake Toxic Chemicals Analysis 3
•
L`
Tetra Tech, Inc.
March 18, 1998
(1982) summarize methods for estimating Ki and Kb from molecular weight, wind speed, and
physical properties of the water body.
The recycle ratio, Fr', contains factors governing sediment interaction, and it represents the ratio
of the rate of sediment feedback of contaminant (i.e., resuspension and diffusion) to the total rate
at which the sediment purges itself of contaminants (i.e., resuspension, diffusion, burial and
decay):
Fr t =
Vu + Vd fd2
Vu + Vd fd2 + Vh + k2z2
(9)
where v" is the upward mass transfer coefficient due to resuspension (L/T), fdZ is the dissolved
fraction in the sediment, Vb is the burial or sedimentation velocity (L/T), k2 is the decay rate in
sediment (1/T), and z2 is the thickness of the "active" sediment layer.
The expression for Fr' involves resuspension and burial velocities that are interdependent and
difficult to measure or calibrate in practice. Therefore, following Chapra (1991), Fr' can be
redefined in terms of a sediment resuspension ratio, which can be taken as a single parameter for
calibration:
Fr = Fr ysb + yd A
(10)
Vsb + Vd A + k2Z2
where the scaled settling velocity (converted to units comparable to sediment scour), VSb, is
m
VSb _ (1 -C P VS (11)
with ? representing sediment porosity, and p the density of sediment solids (M/L3).
The resuspension ratio is then equivalent to
Fr = vu = vu = vu (1-?) P (12)
Vh + Vu vsb Vs M
0
An additional simplifying assumption can be made. If it is assumed that the partition coefficients
in the water and sediment layer are equal, Chapra (1991) shows that diffusive sediment-water
transfer will either be negligible or result in a loss from the water to the sediments. Therefore,
ignoring the diffusion coefficients will either have negligible effect on the solution or result in an
upper-bound (conservative) prediction. The general expressions for loss rates in individual lake
segments, respectively, can then be written as
4 Randleman Lake Project Phase H Report
Tetra Tech, Inc. March 18, 1998
V, _ k1H + vv fd, + 1 _ Fr vsb . vs fP1 (13)
vsb + k2Z2
2. Model Parameterization
Implementation of the fate and transport model requires data or assumptions on a number of
parameters of the chemical and/or the water body. Most of these parameters cannot be specified
with complete precision, although some (e.g., Henry's Law constant) are much more certain than
others (e.g., environmental decay rates). A complete uncertainty analysis is not warranted unless
an initial scoping analysis with conservative assumptions indicates there is at least a potential for
concentrations in excess of risk-based standards.
To complete the scoping analysis, probable ranges were assigned to key parameters whose
estimates are thought to be subject to significant uncertainty. The best estimates and parameter
ranges for water body characteristics are summarized in Table 1. Table 2 provides chemical-
specific parameter values, derived from the literature summarized in Howard (1989, 1990).
Where the literature provides a range of values, the range is also shown in the table.
The fate and transport model was used to predict concentrations of toxic organic chemicals on a
segment-by-segment basis, using the model segmentation described in the Nutrient Reduction
Strategy and Management Plan. Segmentation of the proposed Randleman Lake and watershed
is shown in Figure 1. For compounds derived from the Seaboard Chemical/Riverdale Landfill
site or the High Point Eastside Wastewater Treatment Plant, maximum concentrations are
expected in the Deep River 1 segment, immediately below the source area. Other lake segments
will have lower concentrations. For all compounds, estimated concentrations are also shown for
the water intake segment, Deep River 3B.
Randleman Lake Toxic Chemicals Analysis
•
•
0
Tetra Tech, Inc.
March 18, 1995
Table 1. Parameter Values and Ranges for Toxics Fate and Transport Model:
Water Body Characteristics.
Parameter
Z,A Segment depth, area
qs Segment overflow rate
(m/yr)
M Solids concentration in
water column (mg/1)
foc
P
Vs
Z2

Va
Values
variable
variable
Most likely:
100
Range:
75-150
Organic carbon fraction of 0.07
sediment
Sediment solids density 2.65
(g/cm')
Settling velocity (m/yr) Most likely:
1000
Range:
900-1800
Thickness of active Most likely:
sediment layer (m) 0.05
Range:
0.01-0.1
Sediment porosity 40
(percent)
Resuspension velocity Most likely:
(m/yr) 0.043
Range (for v,
= 900 m/yr):
0.03-0.06
Range (for vs
=1800 m/yr):
0.08-0.11
Source
BATHTUB model specification.
BATHTUB model results, future land use conditions across
range of flows.
Assumed based on typical values in literature and regional
assumptions used in Butcher et al. (1995).
Value assumed for fine depositional sediment based on
typical values in literature and regional assumptions used in
Butcher et al. (1995).
Assumed based on typical values in literature and regional
assumptions used in Butcher et al. (1995).
Settling velocity depends on both turbulence and particle
size. Thomann and Mueller (1987) suggest a range of 900 to
1800 m/yr for Great Lakes. Using Stokes Law, settling
velocity for fine particles (clay with 20-µm clumps) is about
900 m/vr. Most likely value is placed in the low end of the
range to account for probable effects of turbulence in this
narrow impoundment.
Assumed based on typical values given in Thomann and
Mueller (1987).
Assumed based on typical values in literature and regional
assumptions used in Butcher et a/. (1995).
The scaled settling velocity and scour velocityjointly yield
net burial rate. Assume net burial rate of 1 to 3 cm/yr.
Range for scour velocity is then based on range of settling
velocities.
6
Randleman Lake Project Phase 11 Report
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Tetra Tech, Inc.
March 18, 1998
Figure 1. Randleman Lake Watershed Model Segmentation
8 Randleman Lake Project Phase H Report
Tetra Tech, Inc. Adarch 18, 1998
3. Lindane
• In 1992-93, NCDEM's Water Quality Section analyzed numerous water samples for pesticides
and organic chemicals at eight stations in the area proposed for Randleman Lake (NCDEM,
1994). These samples detected one violation of the state standard for dieldrin, and numerous
violations of the state standard for lindane, including violations at Deep River station RL4,
below the High Point Eastside WWTP, station RL5, within the proposed lake at SR 1129, and
station RL9, at the U.S. Highway 220 Bypass above the proposed dam site and near the location
of the proposed water intake (see Figure 2). This report (which was not available when the EIS
and update were prepared) "suggests that Lindane is coming from the WWTP," while "the City
of High Point stated that they believe that residential use of flea dip and shampoo containing
Lindane is the source of these elevated Lindane levels." No other violations of water quality
standards were identified in NCDEM's analyses for pesticides and other priority pollutant
organic chemicals.
Subsequent stream monitoring by DWQ between May 1997 and September 1997 did not detect
Lindane. This suggests that the lindane problem has either been resolved since 1992-93, or is
highly intermittent. Nonetheless, it is advisable to determine whether the maximum loads
observed in stream would present a water quality standard in the proposed lake.
Lindane is listed by EPA as a priority pollutant, requiring water quality standards. The State of
North Carolina has adopted a standard for lindane in all waters of 10 nanograms per liter (ng/1)
• for the protection of aquatic life. EPA risk-based water quality criteria calculated by the Office
of Science and Technology include a recommended maximum concentration of lindane in
surface water for the protection of human health, based on an assumption of exposure via both
drinking water and consumption of contaminated fish, stated as 12.3 ng/1 technical hexachloro-
cyclohexane-y. This criterion accounts for bioaccumulation of lindane in fish. EPA has also
established drinking water standards for lindane at 40 CFR 141.12. The Maximum Contaminant
Level (MCL) and Maximum Contaminant Level Goal (MCLG) for lindane in finished drinking
water are both now set at 200 ng/1(0.2 ppb). The MCLG is a non-enforceable goal that EPA has
determined to represent a safe level of a chemical that will not cause health effects in humans
exposed through drinking water. The MCL is the corresponding enforceable standard. It is
worth noting that the drinking water standard is 20 times higher than the standard for the
protection of aquatic life, due to lindane's high chronic toxicity to many aquatic organisms. The
MCLG for lindane in finished drinking water is also four times greater than the highest
concentration of lindane observed by NCDEM in Deep River.
3.1 Monitoring Data
NCDEM monitoring for ambient concentrations of lindane in the proposed Randleman Lake
watershed is summarized in Table 3, showing results from Richland Creek below the High Point
Eastside WWTP and two monitoring stations downstream of Richland Creek in the Deep River.
In addition, High Point reported a concentration of 0.07 µg/l lindane in Richland Creek on
0 October 16, 1992.
Randleman Lake Toxic Chemicals Analysis

s
High Point Landfill
and Seaboard Chemical
I CD
1
High Point
Eastside WWTP
RL3 Richland Cr
?? (02099484)
13
U`
U'
a o
r__i z
NC s o
2
SR
?vddy
0 1 mile
I
goo 130ch
V,
FIGURE 1
UPPER DEEP RIVER
MONITORING LOCATIONS
AND THE PROPOSED
RANDLEMAN LAKE
? i
0
Tetra Tech, Inc.
March 18, 1998
Table 3. NCDEM Monitoring Data for Lindane (gg/1) in Deep River between High
Point Eastside WWTP and Proposed Randleman Lake Dam
•
Date RL4
Richland Creek
downstream of High
Point Eastside WWTP RL5
Deep River at SR 1129 RL9
Deep River at Hwy 220
Bypass
7/28/92 0.03 0.02 ND
8/26/92 0.03 0.03 0.01 E
9/30/92 ND ND ND
10/27/92 0.02 0.01 E 0.01 E
11/18/92 0.01 E 0.01 E ND
12/14/92 ND ND ND
1/20/93 ND ND ND
2/16/93 ND ND ND
3/31/93 0.005 E ND ND
4/20/93 ND ND ND
5/19/93 ND ND ND
6/16/931 0.01 ND ND
9/22/93 0.02 0.02 0.01
10/7/93 0.05 0.05 0.02 E
5/5/97 ND ND not sampled
6/2/97 ND ND not sampled
7/8/97 ND ND not sampled
8/6/97 ND ND not sampled
9/3/97 ND ND not sampled
Notes: ND Not detected.
E Estimated value below Target Quantitation Limit (generally 0.02 µg/1).
On March 5, 1993, the NCDEM Winston-Salem Regional Office requested the City of High
Point to perform an investigation on potential sources of lindane. In response, the city submitted
14 samples for analysis of lindane in influent and effluent of the WWTP, of which 13 were
Randleman Lake Toxic Chemicals Analysis 11
Tetra "Tech, Inc.
•
•
March 18, 1998
reported. These data (NCDEM, Table 4. Sampling for Lindane (gg/1) in High
1994), summarized in Table 4, Point Eastside WWTP Influent and Effluent.
indicated that lindane was present in
the WWTP plant effluent, but loads
are intermittent and highly variable.
Seven additional samples of effluent
collected between 2/16/96 and
1/23/98 did not detect lindane.
Approximate upper-bound estimates
of the mass of lindane loaded into
the reservoir area can be obtained
from the concentrations observed at
RL4. Flow is not monitored at
RL4, but can be approximated by
using a ratio method and assuming
the change in flow is proportional to
the change in drainage area from the
USGS gage at RL6. For the eight
days on which lindane was
quantified in the water column at
RL4, mass loading rates range from
1.5 to 5.2 µg/s, equivalent to
0.00029 to 0.00099 pound of
lindane per day.
Date Influent
Concentration Effluent
Concentration
3/17/93 <0.02 <0.02
3/20/93 <0.02 <0.02
3/22/93 <0.02 <0.02
3/23/93 1.21 0.03
3/24/93 <0.02 0.03
3/26/93 <0.2 <0.2
3/27/93 <0.2 <0.2
3/28/93 <0.2 <0.2
3/29/93 <0.2 <0.2
3/30/93 <0.02 <0.02
3/31/93 0.22 0.05
4/ 1 /93 <0.02 <0.02
4/2/93 <0.02 0.03
The presence of violations of water Note: Data provided by the City of High Point
quality standards for lindane within
the area that will be impounded for
the proposed Randleman Lake, and indeed near the location of the proposed Deep River arm
water intake, raises concerns for the quality of the source water that must be addressed. It is
clear, however, that concentrations observed by NCDEM in the Deep River under free-flowing
conditions will not be representative of conditions expected following impoundment of
Randleman Lake, since dilution volume, residence time, and opportunity for losses due to
volatilization, sedimentation, and degradation will increase following impoundment. The
analyses presented in the following sections confirm that lindane concentrations will not present
an unacceptable risk to water quality within the proposed Randleman Lake.
3.2 Model Results for Lindane
Simulation of lindane reduction in transport within the lake is obtained using estimates of both
annual and summer growing season segment-to-segment flow rates output by the eutrophication
model, BATHTUB. Summer flows represent minimum dilution capacity, but provide additional
opportunity for degradation and other removal processes to occur. The upper bound estimate of
12 Randleman Lake Project Phase 11 Report
Tetra 'T'ech, Inc. A4arch 18, 1995
mass loading (5 µg/s) was used to provide an upper bound on in-lake concentrations, using the
• range of parameters water body characteristics shown in Table 1 and the range of chemical
characteristics shown in Table 2. In addition, the hydrologic effects for dry years (represented by
1967 flows) and wet years (1975 flows).
As shown in Table 5, the predicted concentrations increase in the wet year (1975) versus the dry
year (1967). Results are shown for the upstream Deep River 1 segment (where concentration is
at a maximum) and the water intake segment (Deep River 313). Over this range of summer
flows, the decrease in degradation associated with faster flow has a greater effect than increased
dilution. Predicted concentrations at the water intake segment will continue to increase with
higher flows up to about 2.5 times the summer segment overflow rates estimated for 1975, after
which further increases in flow result in declining concentrations due to increased dilution. For
comparison, the annual-basis segment overflow rates range from about 3 to 8 times those
estimated for summer 1975 conditions. Annual flows for the dry year 1967 are thus near the
maximum impact combination of low degradation and low dilution. Results for this case are
shown in Table 6.
•
•
Table 5. Estimated Upper Bounds on Lindane Concentration (ng/1) in Randleman
Lake During the Growing Season. (Note: Table shows best estimate and range.)
Flow Regime Deep River 1 Deep River 3B
(below source) (Water Intake)
Dry Year (1967) 5.07 0.010
(3.52-5.86) (0.0066-0.24)
Wet Year (1975) 2.82 0.25
(2.44-2.92) (0.043-0.37)
Table 6. Estimated Upper Bounds on Lindane Concentration (ng/1) Based on Dry
Year Annual Flows. (Note: Table shows best estimate and range.)
Deep River 1 Deep River 3B
(below source) (Water Intake)
1.47 0.43
(1.35-1.49) (0.11-0.53)
In all cases, both the best estimate and the maximum predicted concentrations of lindane at either
water intake location are well below the state water quality standard of 10 ng/1 and drinking
water standard of 200 ng/1, despite conservative assumptions regarding mass loading rates.
Additional reductions in concentration will occur during water treatment, ensuring even lower
concentrations in the finished water.
Randleman Lake Toxic Chemicals Analysis 13
Tetra Tech, Inc. March 18, 1998
In sum, existing lindane discharges do not appear to present any risk of excursion of water
• quality standards in Randleman Lake. The estimates presented are highly conservative because
they assume a constant release of lindane from the High Point Eastside plant at loads near the
maximum loading rate that has been observed, whereas no lindane has been detectable in the
effluent during recent monitoring.
4. Potential Loading from Seaboard Chemical Solvent Recovery and
Riverdale Landfill Sites
Ground water beneath the former Seaboard Chemical solvent recovery and adjacent Riverdale
Landfill sites is known to be contaminated with a variety of organic chemical solvents. Ground
water from this site appears to discharge to the adjacent segment of the Deep River. ERM, the
contractor for the Remedial Investigation of these sites, has not yet completed analysis of site
hydrogeology. At a recent presentation (9/2/97), ERM presented results of additional studies,
including surface water grab samples, and samples from piezometers in the river bed. They
noted that the discharge of a volatile organic compound (VOC) ground water plume to the Deep
River had been confirmed; however, very low concentrations observed in the river indicated
strong attenuation of concentrations by dilution. Instream sampling by NC DWQ also suggests
that ground water from these sites is not resulting in excursions of water quality standards in
stream.
A total of ten organic solvent priority pollutants have been detected in ground water at the site,
• and are analyzed here. These are chlorobenzene, 1,2-dichlorethane, 1, 1 -dichloroethylene
(vinylidene chloride), vinyl chloride, benzene, 2-chlorophenol, methylene chloride
(dichloromethane), 1,1,2,2-tetrachloroethane, 1,1,2-trichloroethane, and toluene. As will be
noted from Table 2, all of these compounds (with the exception of 2-chlorophenol) are highly
volatile and will be expected to move from water to air once discharged from ground water.
Once the proposed Randleman Lake is built, it is expected that the surface water concentrations
of chemicals derived from Seaboard Chemical and Riverdale Landfill will further decrease, due
to increased dilution volume and longer residence time, which will promote volatilization loss, as
well as biodegradation, hydrolysis, or photolysis of some of the chemicals. In addition, filling of
the reservoir will help create a hydraulic barrier which will reduce the flow of contaminated
ground water from these sites.
The Remedial Investigation has not yet yielded firm estimates of rates of ground water flow from
the sites to the river. Thus quantitative estimates of loading rates of contaminants are not
available. A screening approach was therefore taken to assess whether the maximum reasonable
load rate from these sites would potentially result in excursions of water quality standards within
the reservoir. The screening approach included the following extremely conservative
assumptions:
1. Maximum reasonable flow of contaminated ground water from the site. .
2. Maximum observed concentrations in ground water
3. Minimum rates of degradation and loss based on the ranges of parameters in
Table 2.
14 Randleman Lake Project Phase II Report
Tetra Tech, Inc.
March 18, 1998
4. Worst case range of waterbody characteristics from Table 1 (low solids
• concentration, settling velocity, and thickness of active sediment layer; high
resuspension velocity).
5. Analysis for worse case among summer and annual flows during range from wet
to dry years.
This approach will greatly overestimate the likely concentrations which will occur in Lake
Randleman; however, if these very conservative screening estimates can be shown to be still
below relevant water quality standards it can be concluded that contaminated ground water from
the Seaboard Chemical/Riverdale Landfill sites will not result in excursions of water quality
standards in the proposed lake.
In the draft EIS, the rate of flow of contaminated ground water from the site was estimated to be
450 gpd. Review comments by the North Carolina Division of Solid Waste suggested that this
flow rate might be too low, and that discharge from the site might be as high as 5,000 gpd. This
upper bound flow rate was assumed for the screening analysis.
For concentrations, the screening analysis uses the maximum concentrations detected in ground
water modeling in August 1997 and 1989, as reported by NC DWQ and shown in Table 7:
0 Compound Detected Maximum Concentration (µg/1) Sampling Program
Table 7. Maximum Concentrations in Ground Water Monitoring Wells below Seaboard
Chemical Site (as summarized by NC DWQ)

Chlorobenzene 13,000 1997
1,2-Dichloroethane 220 1997
1, 1 -Dichloroethylene 960 1997
Vinyl Chloride 1800 1997
Benzene 6 1997
2-Chlorophenol 33 1997
Methylene Chloride 2600 1989
1,1,2,2-Tetrachloroethane 3800 1989
1,1,2-Trichloroethane 800 1989
Toluene 6200 1989
Using these assumptions, the lake toxics model was applied to estimate maximum screening
upper bound concentrations, as shown in Table 8. Because of the large reduction by dilution and
other factors, the resulting small in-lake concentrations are reported as nanograms per liter (ng/1).
Relevant ambient water quality standards and criteria (see Table 2) are also reported. In each
Randleman Lake Toxic Chemicals Analysis 15
Tetra Tech, Inc.
March 18. 1998
case, the maximum screening upper bound concentration is well below the relevant water quality
• criterion. Actual concentrations are expected to be much lower. Therefore, given the
conservative assumptions employed in the screening analysis, no excursions of water quality
associated with ground water loading from the Seaboard Chemical/Riverdale Landfill sites is
expected.
n
LJ
Table 8. Screening of Toxicants from the Seaboard Chemical/Riverdale Landfill Sites
Compound Maximum Screening Concentration (ng/1) Standard or Criterion
Deep River 1
(below source) Deep River 313
(Water Intake) (ng/1)
Chlorobenzene 38.2 0.70 488,000
1,2-Dichlorethane 0.65 0.013 380
1, 1 -Dichloroethylene 2.8 0.052 57
Vinyl Chloride 4.9 0.084 2,000
Benzene 0.016 0.0002 1,190
2-Chlorophenol 1.6 0.036 180,000
Methylene Chloride 7.3 0.13 4,700
1,1,2,2-
Tetrachloroethane 6.1 0.13 172
1,1,2-Trichlorethane 2.5 0.054 600
Toluene 17.4 0.29 11,000
5. Phenolic Compounds
5.1 DWQ Monitoring for Phenolic Compounds
Between May and September 1997, NC DWQ sampled the Upper Deep River for total
recoverable phenolics. Samples were taken at nine stations. There is no numeric standard for
Class C waters (current classification); however, there is a state standard of 1.0 µg/1 for water-
supply waters. For the 1997 sampling, 36 of 45 samples were greater than 1.0 µg/1, with a
maximum of 52 µg/l. Higher concentrations were seen at Stations RL2 (Deep River at I-85
downstream of High Point Landfill and Seaboard Chemical), RL3 (Richland Creek at SR 1154
upstream of High Point Eastside WWTP) and RL4 (Richland Creek downstream of High Point.
Eastside WWTP), but were always __<6 µg/l at downstream stations RL5 (Deep River at SR 1129)
and RL6 (Deep River at SR 1921). Higher concentrations were again seen further downstream at
16 Randleman Lake Project Phase 11 Report
Tetra Tech, Inc.
March 18, 1998
stations RL 7 (Deep River at SR 1936), RL 8 (Muddy Creek at SR 1936) and RL 9 (Deep River
at Hwy 220 Bypass).
Phenols may enter surface waters from a variety of sources including manufacturing (resins,
plastics, fibers, adhesives, iron and steel, aluminum, leather, and rubber), agriculture (animal
wastes, decomposition of organic wastes, agricultural burning), highway runoff (phenol is a
constituent of automobile exhaust), and landfill leachate. The apparent presence of peak
concentrations in two different areas of the Deep River suggests there may be multiple sources.
One potential source for upstream concentrations (unproven) is the Seaboard Chemical solvent
recovery and Riverdale Landfill site. Another source is demolition landfills near Groometown
Road which discharge to Hickory Creek. An investigation by the DWQ Winston-Salem
Regional Office (memo from Beth Morton to Jay Sauber, June 5, 1997) detected 37 µg/l in
landfill effluent and 12 µg/l in Hickory Creek downstream of the landfill. These landfills contain
significant amounts of veneer and furniture wastes, which are a probable source of phenols from
their constituent resins and adhesives. However, elevated phenol concentrations were not
detected by DWQ at Station RL6, in the Deep River below Hickory Creek. Specific sources
have not been identified in the area near the confluence of Deep River and Muddy Creek, where
concentrations are also elevated.
5.2 Relevant Standards and Identification of Specific Phenolic Compounds
Observations of concentration of phenols in excess of the water supply water quality standard are
. of concern to the proposed reservoir. It should, however, be noted that the standard for phenols
is established for its organoleptic properties, i.e., to prevent taste and odor problems in drinking
water. The standard is not required to protect either human health or aquatic life (although
certain individual phenols, such as 2-chlorophenol, do have water quality criteria established by
EPA). The state standards for WS-IV waters are (15A NCAC 213.0211 (f)(3)(B)):
Phenolic compounds: not greater than 1 µg/l (phenols) to protect water supplies
from taste and odor problems due to chlorinated phenols; specific phenolic
compounds may be given a different limit if it is demonstrated not to cause taste
and odor problems and not to be detrimental to other best usage;
Observations on total phenolics such suggest a potential concern, but do not necessarily imply
contravention of the water quality standard if the compounds present are not chlorinated phenols.
Indeed, all of the 1997 DWQ samples from stations RL1, RL3, RL5, RL6, RL7, and RL8 were
also submitted for pesticide/organics analysis by gas chromatography, including analysis of
semi-volatiles by EPA Method 625, which included quantification for 11 phenolic compounds:
4-chloro-3-methylphenol, 2-chlorophenol, 2,4-dichlorphenol, 2,4-dimethylphenol, 2,4-
dinitrophenol, 2-methyl-4,6-dinitrophenol, 2-nitrophenol, 4-nitrophenol, pentachlorophenol,
phenol, and 2,4,6-trichlorophenol. None of these phenols was detected above quantitation limits
(generally 10 µg/1); however, pentachlorophenol was detected below quantitation limits in 7 out
of 30 samples with estimated concentrations ranging up to 0.07 µg/1. Pentachlorophenol,
formerly used as a wood preservative, is commonly found in the environment. North Carolina
does not have a specific standard for pentachlorophenol, however, the EPA criterion for the
Randleman Lake Toxic Chemicals Analysis 17
Tetra Tech, Inc.
Harch 18, 1995
protection of human health through consumption of water and aquatic organisms is 1,000 µg/l,
while the fresh water chronic criterion for the protection of aquatic life is 13 µg/l. The highest
observed concentration in the Deep River is almost 200 times smaller than the fresh water
chronic criterion.
The EPA Method 625 scan includes the chloro and nitro-substituted phenols which are most
likely to cause taste and odor problems and are the intended targets of the North Carolina
standard for total phenols. It thus appears likely that the phenols which are present do not meet
the intent of the North Carolina standard "to protect water supplies from taste and odor problems
due to chlorinated phenols". Further investigation may be necessary, however, to determine the
exact nature of those phenols which are present in Deep River waters. Presumably, these may
represent some of the unidentified peaks reported on DWQ's analyses of semi-volatile
compounds (see Section 6).
5.3 Analysis of Phenol Loads
Concentrations of phenolic compounds reported by DWQ showed considerable variability,
suggesting intermittent rather than steady loading. Once the lake is impounded, long-term
average loading rates will be more significant than transient stream concentrations. DWQ
samples from the main stem of the Deep River can be converted to approximate loading rates by
using daily average flow data from the USGS gage # 02099500, which is co-located with DWQ
sampling station RL 6. For the DWQ samples, all of which occurred at low to moderate flows,
the gaged flow is assumed to apply equally at stations RL2, RL5, RL6, RL7, and RL9. This will
tend to over-estimate loads at the upstream stations RL3 and RL5, and may under-estimate loads
at RU and RL9, but provides an initial estimate of the loading rate. Estimated phenol loads
from the DWQ sampling are summarized in Table 9.
Table 9. Estimated Mass Loading Rate of Phenolic Compounds (mg/sec)
in the Deep River from NC DWQ 1997 Sampling
Station RL2
Deep River
at 1-85 RL5
Deep River
at SR 1129 RL6
Deep River
at SR 1921 RL7
Deep River
at SR 1936 RL9
Deep River at
Hwy 220 Bypass
Sample count 5 5 5 5 5
Maximum 97.1 6.6 39.5 110.4 371.1
Minimum 0.5 1.4 1.4 4.2 27.6
Average 23.3 3.7 10.2 41.0 114.4
Median 3.9 3.9 4.0 32.1 30.7
The load estimates show a wide range, and the averages are increased by the presence of a few
high-mass samples. Given the small sample size and the apparently intermittent nature of
loading, the median or 50' percentile value is likely to be a more reliable indicator of long-term
18 Randleman Lake Project Phase H Report
Tetra Tech, Inc. March 18, 1998
central tendency. This suggests that the average phenolic load in the upper portion of the
proposed reservoir is on the order of 5 mg/s, while the load in the lower portion of the reservoir
is on the order of 35 mg/s.
C]
Phenols encompass a wide variety of organic compounds, of differing environmental properties.
Most phenols are, however, expected to biodegrade rapidly in the environment, although nitrate
and chlorine substitution on the phenol will impede degradation. For instance, phenol itself will
completely biodegrade in aerobic water over a time span of hours to days, while the more
resistant 2-chlorophenol is expected to completely degrade in rivers in from 13 to 36 days
(Howard, 1989). Rapid degradation in the Deep River system is suggested by the fact that high
peak concentrations near the Seaboard Chemical/Riverdale Landfill (RL2) site are not seen by
the time flow reaches the Deep River at SR 1129 sampling station.
What concentrations of phenolics can be expected in the reservoir? To perform a conservative
analysis for the unidentified phenols it is assumed these compounds have the characteristics of 2-
chlorophenol (see Table 2), which is more resistant to degradation than most unchlorinated
phenols, combined with the minimum values for solids concentration and settling velocity, and
maximum value for resuspension velocity given in Table 1 to provide an upper bound for a
screening analysis. A lower bound is provided by assuming the "most likely" characteristics of
unsubstituted phenol, combined with "most likely" solids dynamics. The resulting range, across
all flow regimes, of predicted lake segment concentrations, given loading of 5 mg/s to Deep
River 1 and 35 mg/s to Deep River 3B, is shown in Table 10.
Table 10. Range of Predicted Concentrations of Phenolic
Compounds in Randleman Lake
Segment Minimum (µg/1) Maximum (µg/1)
Deep River 1 0.31 4.4
Deep River 2 0.0057 0.45
Deep River 3A 0.00002 0.13
Deep River 3B 0.68 9.0
Muddy Creek 2 2,3 x 10g 0.10
Near Dam 7.8 x 1012 0.005
These results suggest that there is a possibility of exceeding the state water quality standard for
total phenols in the Deep River 1 segment, and in the Deep River 3B segment, if the
undetermined load of phenols enters directly into this segment. However, as noted above, it
appears unlikely that the unidentified phenols present in the Deep River are the problematic
chlorinated phenols covered by the standard. Once the lake is impounded, residence times will
increase dramatically, leading to increased opportunity to remove phenols via biodegradation.
Randleman Lake Toxic Chemicals Analysis 19
Tetra Tech, Inc. Alarch 18, 1998
Thus concentrations are expected to decline rapidly with distance away from any source of
loading.
In sum, unidentified phenolic compounds are not expected to present a water quality problem, as
chlorinated phenols are not present at significant levels. Further investigation may, however, be
needed to determine the source of phenols present in the lower portion of the proposed
Randleman Lake.
6. Unidentified Organic Chemicals
In 1992-1993 (NCDEM 1994) and again in 1997 (unreleased draft provided by DWQ), the
North Carolina Division of Water Quality collected water quality samples from the Upper Deep
River for organic substances analysis. A total of 87 samples were analyzed for organic
chemicals in 1992-93 from seven stations, plus the High Point Eastside WWTP effluent. In
1997, 30 samples were analyzed from six stations, as summarized in Table 11. In reporting these
data, DWQ noted many "unidentified peaks" in the organics analyses. These are listed in the
tables summarizing the monitoring data as "unidentified chlorinated pesticide peaks,"
"unidentified acid herbicide peaks," and so on, giving the impression that a significant number of
unidentified pesticides were present. The number of unidentified peaks was greatest at the two
stations below the WWTP (RL4 and RL5); however, unidentified peaks were noted at all stations
except for the single sample at RL7A.
Examination of the original laboratory reports, plus personal communication with Ray Kelling at
the State Water Quality Laboratory (June 6, 1997), reveals that the summary tables provided by
the laboratory are somewhat misleading. That is, the summary in NCDEM (1994) lists, for
example, "unidentified chlorinated pesticide peaks." The laboratory, however, did not render any
judgments on the probable identity of unidentified compounds. Rather, its reports list the count
of "unidentified peaks" noted on the analysis for chlorinated pesticides. These peaks thus appear
on the same analytical method used to detect chlorinated pesticides, but the peaks may well be
other types of compounds, including naturally occurring compounds.
The State Water Quality Laboratory reported results for organic compounds in the Deep River
samples in five categories. All analyses used standard EPA-approved gas chromatographic (GC)
methods, which are matched to the reporting categories as follows:
Chlorinated Pesticides and PCBs by Electron Capture Detection. This report
provides analyses for chlorinated compounds (51 in 1992-93, 54 in 1997) and
uses EPA Method 608, "Organochlorine Pesticides and PCBs" (40 CFR Part 136,
Appendix A). This is a standard GC method coupled with an electron capture
detector (ECD).
• Acid Herbicides by Electron Capture Detection. This report includes 16
compounds such as 2,4-D, dicamba, and pentachlorophenol, and uses EPA
Method 8151 (US EPA 1986), "Chlorinated Herbicides by GC". This is a
capillary column GC method using methylation and analysis by ECD.
20 Randleman Lake Project Phase H Report
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March 18, 1995
Table 11. NCDEM Sampling for Organic Chemicals, Deep River, 1992-1993 and 1997.
Sampling Location Number of Maximum Number of Total Number of
Sampling Unidentified Peaks for Unidentified
Events a Single Sample Event Peaks
RL 1. Deep River at SR 1113 upstream of 1992-93: 14 12 28
High Point Landfill and Seaboard Chemical 1997: 5 18 46
RL3. Richland Creek at SR 1154 upstream 1992-93: 14 11 41
of High Point Eastside WWTP 1997: 5 19 73
RL4. Richland Creek at SR 1145 1992-93: 14 86 643
downstream of High Point Eastside WWTP 1997: 5 19 179
RL5. Deep River at SR 1129 1992-93: 14 56 332
1997: 5 41 137
RL7. Deep River at SR 1936 1992-93: 0 - -
1997: 5 41 132
RL7A. Muddy Creek at SR 1944 1992-93: 1 0 0
1997: 0 - -
RL8. Muddy Creek at SR 1936 1992-93: 14 16 66
1997: 5 11 39
RL9. Deep River at U.S. 220 Bypass 1992-93: 14 34 164
1997: 0 - _
High Point Eastside WWTP Effluent 2 53 102
Organophosphate Pesticides by Flame Photometric Detection. This report
includes 25 compounds such as chlorpyrifos, diazinon, and parathion, and uses
EPA Method 8141A (US EPA 1986), "Organophosphorus Compounds by Gas
Chromatography". This is a capillary column GC technique with a flame
photometric detector.
Semivolatile Organics. This report covers semivolatile compounds (65 in
1992-93, 66 in 1997), including a variety of phenols, polyaromatic hydrocarbons
(PAHs), phthalate esters, nitroaromatics, and other compounds, and uses EPA
Method 625, "Base/Neutrals and Acids" (40 CFR Part 136, Appendix A). This is
a GC method with mass spectrometry, capable of detecting a wide variety of
organic compounds.
• Volatile Analysis. This report covers 54 compounds, primarily purgeable
halocarbons and aromatics, and uses EPA Methods 601 and 602 (40 CFR Part
136, Appendix A). Method 601, "Purgeable Halocarbons," is a purge and trap GC
method with a halide-specific detector. Method 602, "Purgeable Aromatics," is a
purge and trap GC method with a photoionization detector.
Randleman Lake Toxic Chemicals Analysis 21
Tetra Tech, Inc.
March 18, 1998
During the course of the Deep River sampling, unidentified peaks were recorded by four of the
five GC methods listed above (Table 12). By far the largest number of unidentified peaks were
detected by the method used to identify chlorinated pesticides and PCBs (EPA Method 608),
followed by peaks detected by the method for acid herbicides (EPA Method 8151).
0 Station Chlorinated Acid Semivolatile Organophosphate Volatile
To address the significance of these unidentified peaks, a brief discussion of GC analytical
methods is useful. GC methods are used to separate multiple substances in a sample based on
their molecular properties (molecular weight, polarity, volatility, etc.). The substances in a
sample are identified by measuring the amount of time it takes for them to travel through a
chromatographic column and reach the detector. This "retention time" is compared to a "library"
of characteristic retention times for a large number of previously studied organic substances for
which calibration standards are available. Concentration is then estimated based on the area of
the chromatogram peak and a calibrated response factor for the compound. Different detectors
are used for their sensitivity and/or selectivity for a certain class of chemicals. For example, the
electron capture detector is known to be highly sensitive to poly-halogenated hydrocarbons,
though it has relatively poor selectivity (i.e., it will detect many substances other than just poly-
halogenated hydrocarbons).
Table 12. Sample Count of Occurrence of Unidentified Peaks by Station and Method.
(Note: Table shows number of occurrences out of total number of samples for 1992-93 and 1997
sampling combined.)
Pesticides and
PCBs Herbicides Organics Pesticides Organics
RL1 14/19 7/19 0/19 0/19 0/19
RL3 11/19 8/19 0/19 5/19 0/19
RL4 19/19 18/19 8/19 11/19 0/19
RL5 19/19 16/19 6/19 6/19 0/19
RL7 515 515 4/5 5/5 015
RL7A 0/1 0/1 0/1 0/1 0/1
RL8 15/19 11/19 10/19 0/19 0/19
RL9 14/14 8/14 2/14 1/14 0/14
High Point
Effluent 2/2 2/2 0/2 2/2 0/2
An "unidentified peak" is a peak on the GC chart-indicating a substance recorded by the
detector-that is not in the "library" being used by the laboratory. Although each method listed
above has been optimized for detection of a specific class of chemicals, that does not by any
22 Randleman Lake Project Phase 11 Report
Telra Tech, Inc. March 18, 1998
means guarantee that only that type of chemical will be detected by the method. In other words,
a peak detected by Method 608 is not necessarily a chlorinated pesticide or PCB.
The State Water Quality Laboratory attempts to characterize unidentified peaks where possible.
When such peaks occur in the chromatogram above a threshold activity level (indicating
relatively high concentration), the Laboratory routinely follows up with additional analyses using
mass spectrometry (MS) methods, by which the chemical composition of the unknown molecule
can often be deduced. According to Ray Kelling (personal communication, July 29, 1997), the
activity level threshold for proceeding to MS analysis is equivalent to an approximately 5 µg/l
concentration in water for most compounds. None of the unidentified peaks on the chlorinated
pesticide, acid herbicide, or organophosphate pesticide GC scans in the Deep River samples were
present at sufficient concentrations to allow further identification by MS. The fact that no
unidentified peaks had activities high enough to merit further study is an indication that they
were present at low concentrations. On the semi-volatile scan, many of the unidentified peaks
presumably represent the phenolic compounds discussed in the previous section.
It should also be noted that the chemical "libraries" used by the state for the five analyses
together comprise over 200 different organic substances, including a majority of the organic
priority pollutants identified by EPA as posing a risk to the health of humans or aquatic
organisms. (The analyses requested do not include a separate analysis for nitrogen pesticides, for
which the State Laboratory uses Hall detection. Many of the nitrogen pesticides will show up on
other methods, but some common pesticides such as atrazine and simazine will not. Certain
• other priority pollutants requiring special analyses, such as dioxins, were also not examined.)
The relative comprehensiveness of this library reduces the probability that the unidentified
substances were substances that represent a threat, particularly at the low concentrations at which
they were found. It is also possible that some of the unidentified peaks could have been caused
by substances that were identified by one of the other methods. For example, phthalate esters
may cause unidentified peaks in Method 608, but many of these can be identified by the GC-MS
method used by the state to detect semivolatile organics when present in sufficient concentration.
The unidentified peaks detected by the State Laboratory likely include a mixture of naturally
occurring compounds, synthetic compounds contained in nonpoint runoff, and compounds
associated with the High Point Eastside WWTP effluent. Each of the EPA GC methods (40 CFR
Part 136, Appendix A) contains cautions on potential matrix interferents, indicating the common
presence of naturally occurring unidentified peaks. There are, for instance, a wide variety of
naturally occurring chlorinated organic compounds frequently found at low concentrations in the
environment (Gribble 1994), many of which may appear on a Method 608 analysis as
unidentified peaks. Some synthetic organic compounds that are not included in the list of
substances identified by EPA methods but show up as unidentified peaks are likely to be
associated with nonpoint runoff from urban and residential areas. The WWTP effluent contains a
variety of synthetic organic compounds loaded by residential, commercial, and industrial
wastewater. Finally, the disinfection process at the WWTP produces a variety of chlorinated
organic compounds, which likely accounts for much of the increase in unidentified peaks below
the WWTP. Even in the WWTP effluent samples, however, the unidentified peaks were not
present at sufficient concentration to allow further resolution by MS.
Randleman Lake Toxic Chemicals Analysis 23
Tetra Tech, Inc. March 18, 1998
In sum, the presence of unidentified peaks on the organic chemical analyses is an expected and
. usual occurrence. Given the facts that most organic priority pollutants are identified by the
methods used, and concentrations in the unidentified peaks are below the threshold required to
pursue identification by mass spectrometry, it is unlikely that any human health risk is associated
with these unidentified compounds.
REFERENCES
Butcher, J., T. Clements, A. Beach, K. Brewer, D. Korn, N. Archambault, P. Kellar and G.
Pesacreta. 1995. Falls Lake Watershed Study, Final report. Prepared for The North Carolina
Department of Environment, Health, and Natural Resources. The Cadmus Group, Durham, NC.
Chapra, S.C. 1991. Toxicant-loading concept for organic contaminants in lakes. J. Env. Eng.
117(5): 656-677.
Gribble, G.W. 1994. The natural production of chlorinated compounds. Environ. Sci. Technol.
68:1.
Mackay, D. 1981. Environmental and laboratory rates of volatilization of toxic chemicals from
water. pp. 303-322 in J. Saxena and F. Fisher (eds.), Hazard Assessment of Chemicals, Current
Developments, vol. I. Academic Press, New York.
is Mills, W.B., J.D. Dean, D.B. Porcella, S.A. Gherini, R.J.M. Hudson, W.E. Frick, G.L. Rupp, and
G.L. Bowie. 1982. Water Quality Assessment: A Screening Procedure for Toxic and
Conventional Pollutants. Athens Environmental Research Laboratory, U.S. Environmental
Protection Agency, Athens, GA.
NCDEM. 1994. Water Quality Monitoring Data for Waters in the Upper Deep River Area, July
28, 1992 - October 7, 1993. North Carolina Division of Environmental Management, Water
Quality Section, Environmental Sciences Branch, Raleigh, NC.
Thomann, R.V. and D.M. Di Toro. 1983. Physico chemical model of toxic substances in the
Great Lakes. J. Great Lakes Res. 9(4): 474-496.
Thomann, R.V., and J.A. Mueller. 1987. Principles of Surface Water Quality Modeling and
Control. Harper & Row, New York.
US EPA. 1986. Test Methods for Evaluating Solid Waste: Physical/Chemical Methods, 3rd ed -
4 vols. November 1986; Final Update I, July 1992, Final Update II, September 1994, IIA August
1993, Final Update IIB and Proposed Update III, January 1995. EPA 530/SW-846.
Vollenweider, R.A. 1969. Moglichkeiten and Grenzen Elementarer Modelle der Stoffbilanz von
Seen. Arch. Hydrobiol. 66(1): 1-36.
C _J
24 Randleman Lake Project Phase H Report
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Section 4
Fecal Coliform Bacteria in the Proposed
Randleman Lake
TetraTech, Inc.
March 18, 1998
•
•
HAZEN AND SAWYER
•
TMO
Fecal Coliform Bacteria in the Proposed Randleman Lake
Prepared for Piedmont Triad Regional Water Authority
Tetra Tech, Inc.
March 18, 1998
This memorandum summarizes recent monitoring for fecal coliform bacteria within the
watershed of the proposed Randleman Lake. High concentrations of fecal coliform bacteria have
been observed on occasion within free-flowing streams in this area. A modeling analysis of
expected conditions after impoundment of the lake suggests that the observed bacterial loads will
not result in excursions of North Carolina water quality standards within the proposed reservoir.
In addition, a variety of mitigation measures will reduce the bacterial load prior to impoundment
of the reservoir, particularly loads associated with dairy operations.
Monitoring Data
Water quality monitoring by the North Carolina Department of Environment and Natural
Resources, Division of Water Quality (DWQ) indicates excursions of water quality standards for
fecal coliform bacteria at many sites within the watershed of the proposed Randleman Lake in
the upper Deep River basin in Randolph and Guilford counties, NC. The relevant North Carolina
• water quality standards for fecal coliform bacteria are a geometric mean of less than 200
organisms per 100 ml (based on at least 5 samples during a 30-day period), and less than 20% of
samples with more than 400 organisms per 100 ml.
The DWQ undertook two rounds of five samples within a month in June 1993 and August 1997
to examine compliance with the geometric mean water quality standard. Additional coliform
samples were collected during regular monthly monitoring. Results are summarized in Table 1
(note that we have followed the DWQ in including only the lower of duplicate sample results
collected on August 6, 1997). Sampling locations are shown in Figure 1.
Observed conditions were generally worse in 1997 than 1993. Occasional high concentrations of
fecal coliform bacteria are expected in most watersheds due to washoff of nonpoint pollution,
which is why the standard is written in terms of the geometric mean and 80`h percentile, rather
than specifying a maximum. Many of the highest concentrations observed in 1997 were from
samples on June 2, following a rain event. However, high concentrations were also seen during
dry weather flows.
The sampling results appear to delineate two general areas of bacterial contamination in the
watershed of the proposed Randleman Lake. The first is the upstream portion of the watershed
near the High Point urban area, particularly in Richland Creek and the portion of Deep River
immediately below the confluence with Richland Creek (stations RL3-RL6). The second is in
• the lower portion of the watershed of the proposed reservoir, both above and below the
confluence with Muddy Creek (RL7-RL9).
Randleman Lake Fecal Coliform Bacteria Analysis
Tetra Tech, Inc.
•
•
March 18, 1998
Table 1. NC DWQ Fecal Coliform Bacteria Monitoring, Upper Deep River

Station 1993 Sampling 1997 Sampling
Geometric Percent > Maximum Geometric Percent > Maximum
Mean 200 per Observed Mean 200 per Observed
(June) 100 ml (August) 100 ml
RL 1. Deep River at 91 18 760 31 20 300
SR 1113
RL 2. Deep River at 105 24 700 55 40 410
I-85
RL 3. Richland 158 33 400 708 90 5000
Creek above WWTP
RL 4. Richland Creek 30 6 240 190 50 300
below WWTP
RL 5. Deep River at 46 17 250 381 60 800
SR 1129
RL 6. Deep River at 17 6 200 196 70 800
SR 1921
RL 7. Deep River at 17 17 210 252 20 500
SR 1936
RL 8. Muddy Crk at 224 78 12000 2158 100 >9900
SR 1936
RL 9. Deep River at 229 56 1500 655 80 4100
I-220 Bypass
Muddy Creels at SR 288 40 1000 - - -
1922
Muddy Creek at SR 851 100 1300 - - -
141

In the upstream area, the concentrations in Richland Creek, which drains High Point, are
consistent with reported concentrations for urban runoff (Doran et al., 1981). The High Point
Eastside WWTP does not appear to be the source of the problem, as concentrations in Richland
Creek decline as flow passes the WWTP outfall.
0 Downstream concentrations were highest in Muddy Creek in both 1993 and 1997, and these
loads also apparently result in increased concentrations downstream in the Deep River at the
Randleman Lake Project Phase 11 Report
•
•
11
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and Seaboard Chemical
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Eastside WWTP
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FIGURE 1
UPPER DEEP RIVER
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RANDLEMAN LAKE
1
Tetra Tech, Inc. March 18, 1998
Highway 220 Bypass (RL 9). In 1997 concentrations were also elevated above standards in the
• Deep River above the confluence with Muddy Creek (RL 7). A possible source of these elevated
concentrations is runoff from dairy farms, of which four are located in the Muddy Creek drainage
(above RL8), and two in the Deep River drainage (between RL6 and RL7). All the DWQ
sampling addresses summer conditions in which flow was low to moderate, allowing high
impacts instream from localized runoff events.
Screening Analysis
Observed concentrations of fecal coliform bacteria in the upper Deep River are unacceptable for
a water supply watershed, and the use of this portion of Deep River for recreational uses is also
currently impaired by high bacterial concentrations. Construction of the proposed Randleman
Lake will, however, result in a significant change in conditions, most notably through increased
residence time and dilution volume, which will reduce fecal coliform concentrations in the
reservoir relative to those observed in the river. Increased residence time is particularly
important, as it provides a greater opportunity for natural die-off of coliforms. Characteristics of
reservoirs, such as high insolation and active natural bacterial and fungal populations, also tend
to increase the rate of destruction of enteric organisms.
Loading of fecal coliform bacteria is expected to be intermittent, responding in part to
rainfall-washoff events. A conservative screening analysis may, however, be undertaken by
assuming a constant loading rate (which will yield a higher concentration than intermittent
loading at the same rate).
• Expected fecal coliform concentrations within the proposed reservoir under conditions of a
constant load may be calculated, for a mixed reservoir segment, as (Thomann and Mueller,
1986):
C= W
Q + KB V
(1)
in which C is concentration (organisms per volume), W is the loading rate (organisms per time),
Q is the rate of flow through the segment, KB is the coliform die-off rate (time -'), and V is the
volume of the segment. A summary of fecal coliform die-off rates in freshwater by Mitchell and
Chamberlain (1978; cited in Bowie et al., 1985) suggests a range for KB for lakes ranging from
0.052 to 0.114 per hour.
Estimates of Fecal Coliform Bacteria Load
Flow gaging in the Deep River is available at sampling station RL 6 (USGS gage 02099500).
Multiplying daily average flows times 1997 observed fecal coliform concentrations yields
estimates of coliform load ranging from 1.4 x 10' organisms per hour (July 28, 1997) to 1.8 x
10" organisms per hour (May 5), with a geometric mean of 3.5 x 109 organisms per hour. No
flow monitoring is available for Muddy Creek, but loads there are presumably greater than those
• in the upper Deep River, as concentrations in the Deep River at RL 9 (below Muddy Creek) are
higher than those seen at RL 6, despite the addition of incremental flow.
Randleman Lake Project Phase 11 Report
Tetra Tech, Inc. March 18, 1995
Coliform loads observed at RL 6 are approximately lognormally distributed. The 80"' percentile
of a lognormal distribution may be estimated as (Gilbert, 1987):
x.so = exp(µ + Z.80,sl,) (2)
where µ is the mean of the natural logarithms of observations, Z80 = 0.8416 is the critical value
of the standard normal distribution, and sy is the sample standard deviation of the logarithms.
This yields an estimate of the 80"' percentile of the load at RL 6 of 1.6 x 1010 organisms per hour.
Concentrations in Upper Segments of the Lake
For modeling analysis, Randleman Lake has been divided into seven segments (Figure 2), as
documented in the Nutrient Reduction Strategy and Implementation Plan. To provide a
screening analysis of the potential upper bound fecal coliform bacteria concentrations in each
segment of the upper portion of the proposed lake, the following conservative assumptions were
made:
• The fecal coliform load is discharged directly to each lake segment at a constant
load rate of 1 x 10" organisms per hour (rounded up from the 80`h percentile
estimate based on observations at station RL 6).
• Flow within the lake is set to summer conditions for an extreme low flow year
(based on observations for the drought year 1967), which results in minimum
dilution and maximum bacterial concentration within each segment receiving
load.
• Analysis is undertaken over the full reported range of KB values for lakes.
When a load of 1 x 10" organisms per hour is assumed to be introduced directly to any of the
upper lake segments, application of Equation (1) yields the predicted range of the 801" percentile
of fecal coliform concentrations (organisms per 100 ml) shown in Table 2.
Table 2. Estimated Range of 80`h Percentile', Concentration of Fecal Coliform Bacteria
in Upper Segments of the Proposed Randleman Lake During Low Flow
(organisms per 100 ml)
Deep River 1 Deep River 2 Deep River 3A Deep River 313
104-223 10-23 5-11 18-39
In all cases, the predicted range is less than the 400 organisms per 100 ml standard for the 80"'
percentile even under low flow conditions; further, these conservative predictions are less than
the 200 organisms per 100 ml geometric mean standard in all segments except Deep River 1,
reflecting the fact that coliform die-off will be substantially increased in a lake compared to
existing free-flowing stream conditions. Predicted 'concentrations are highest in the Deep River
segment, because dilution volume is small and residence time short.
•
Randleman Lake Fecal Coliform Bacteria Analysis
Tetra Tech, Inc. March 18, 1998
L

•
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Deep River 2
Deep River 1
----------------- ---------- ------ Guil ord County
Ra olph County
Muddy Creek 1 3A Dee River 3
N B
Mu dy Creek 2
Dam
Figure 2. Randleman Lake Watershed Model Segmentation
6 Randleman Lake Project Phase II Report
Tetra Tech, Inc. March 18, 1998
Concentrations in Lower Segments of the Lake
For the downstream segments, the magnitude of existing loads from Muddy Creek is not known.
However, these lake segments have longer residence times and larger volumes, and thus can be
expected to further diminish fecal coliform bacteria concentrations through natural die off. For a
screening analysis, a fecal coliform bacteria load of 1 x 1012 organisms per hour is assumed (that
is, ten times greater than the 801h percentile of the upstream load) for segments Muddy Creek 2
and Near Dam, which are downstream of dairy operations. A load of 1 x 10" (same as for the
upper segments) was assumed for Muddy Creek 1, which is upstream of the dairy operations.
Loads of these magnitudes would still result in in-lake concentrations well less than 100
organisms per 100 ml in the downstream Muddy Creek 2 and Near Dam lake segments, as shown
in Table 3, while concentrations in Muddy Creek 1 would be less than 200 organisms per 100 ml.
As with the screening analysis for the upper lake segments, these results are obtained with the
conservative assumption of summer low flow conditions.
Table 3. Estimated Range of 80`h Percentile Concentration of Fecal Coliform Bacteria
in Downstream Segments of the Proposed Randleman Lake During Low Flow
(organisms per 100 ml)
Muddy Creek 1 Muddy Creek 2 Near Dam
32-144 59-130 35-76
It should be noted that the screening analysis presented above yields predicted concentrations as
segment-wide averages. Excursions of the standard for fecal coliforms might still exist in the
locality of any concentrated sources (e.g., dairy feedlot runoff).
Mitigation Measures
PTRWA recognizes that it is general good management practice to minimize loading of enteric
bacteria to a water supply reservoir. While segment average concentrations are expected to meet
water quality standards, the presence of any concentrated sources of loads might lead to localized
excursions of the standards. Accordingly, the following load-mitigation measures are proposed:
• Each of the five dairies in the watershed with over 100 head is developing a waste
management plan, as required under 15A NCAC 2H.0200. Implementation of these plans
is behind the originally-anticipated schedule, which means that observations during 1997
do not reflect the load reduction which will be achieved by waste management planning.
The owners of the five dairies have applied for a Special Agreement in accordance with
Senate Bill 1217, which allows additional time for plan approval to an operator who
registered by September 1, 1996 and who makes a good faith effort to obtain an approved
animal waste management plan by the December 31, 1997 deadline. The Applications
for Special Agreement show that each dairy will institute significant improvements in
waste handling, waste storage, runoff control, and land application. These improvements
are scheduled to be completed by late 1998, and should significantly reduce the fecal
Randleman Lake Fecal Coliform Bacteria Analysis
Tetra Tech. Inc.
March 18, 1998
coliform loads generated by the major dairy operations. A complete summary of status of
dairy waste management plans is provided in PTRWA's response to DWQ comments on
the draft Nutrient Reduction Strategy and Management Plan.
A sixth small dairy, not subject to waste management planning requirements, is located
along the Deep River in the reservoir critical area. PTRWA anticipates acquisition and
elimination of this dairy, although negotiations are not complete.
Two of the dairies which drain to Muddy Creek (Green Valley Farm and Cashatt Dairy)
currently have active pasture land which lies within PTRWA's acquisition boundaries for
the reservoir. These pastures will be acquired by PTRWA following completion of
negotiations and prior to impoundment of the reservoir and eliminated from animal
operations.
A wetland will be constructed on Richland Creek upstream of the wastewater treatment
plant. This will provide interception of urban runoff from High Point and additional
opportunity for inactivation of bacterial loads before they reach the reservoir.
A wetland will be constructed on Muddy Creek, which will provide interception of urban
runoff from Archdale and part of High Point, providing additional opportunity for
inactivation of bacterial loads before they reach the reservoir.
• One small domestic-type wastewater discharger (Hidden Forest MHP, permitted flow 0.1
. MGD) discharges to a tributary of the Deep River near the boundaries of the proposed
reservoir. Another small domestic-type wastewater discharger (Melbille Heights,
permitted flow 0.0315 MGD) discharges to Muddy Creek near Archdale. Small
dischargers can be problematic because of limited monitoring and operational expertise.
These small dischargers will be removed and piped to the High Point municipal sewer
system.
PTRWA will work with local jurisdictions to ensure that enforcement of all ordinances
regarding on-site disposal of domestic wastewater receives high priority.
References
Bowie, G.L. et al. 1985. Rates, Constants, and Kinetic Formulations in Surface Water Quality
Modeling (2" d Edition). EPA/600/3-85/040. U.S. Environmental Protection Agency,
Environmental Research Laboratory, Athens, GA.
Doran, J.W., J.S. Schepers, and N.P. Swanson. 1981. Chemical and bacteriological quality of
pasture runoff. J. Soil Water Conserv.. May-June: 166-171.
Gilbert, R.O. 1987. Statistical Methods for Environmental Pollution Monitoring. Van Nostrand
Reinhold, New York.
•
Randleman Lake Project Phase H Report
Tetra Tech, Inc.
March 18, 1998
. Mitchell, R. and C. Chamberlin. 1978. Factors affecting the survival of indicator organisms in
the aquatic environment. In G. Berg. (ed.), Indicators of Enteric Contamination in Natural
Waters. Ann Arbor Press, Ann Arbor, MI.
Thomann, R.V. and J.A. Mueller. 1987. Principles of Surface Water Quality Modeling and
Control. Harper & Row, New York.
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Randleman Lake Fecal Coliform Bacteria Analysis
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Section 5
Support Documentation for Nutrient Load
and Eutrophication Model
TetraTech, Inc.
February 1998

Tetra Tech, Inc.
cEnusnuE Randleman Lake Project
``•-' ' Support Documentation for
Nutrient Load and
Eutrophication
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Tetra Tech, Inc. February 1998
• TABLE OF CONTENTS
1. INTRODUCTION .........................................................1
2. LAKE EUTROPHICATION MODEL ........................................... 1
2.1 Black & Veatch Application ......................................... 2
2.2 Review and Revisions to Eutrophication Modeling Assumptions ............ 4
3. WATERSHED MODEL ....................................................13
3.1 Rainfall/Runoff Model ............................................. 14
3.2 Nonpoint Nutrient Loading Model ................................... 16
4. APPLICATION ..........................................................19
5. REFERENCES ..........................................................21
6. BATHTUB INPUT FILES .............................. ................23
•
LIST OF FIGURES
Figure 1. Schematic Diagram of Segmentation for BATHTUB Model of Randleman
LakeWatershed (from Black & Veatch, 1990) ............................... 4
Figure 2. BATHTUB Segmentation Used by Black & Veatch .......................... 9
Figure 3. Revised BATHTUB Segmentation for Randleman Lake ...................... 10
Figure 4. Schematic Diagram of Revised Segmentation for BATHTUB Model of
Randleman Lake .....................................................11
?.J
Randleman Lake Nutrient Load and Eutrophication Model i

Randleman Lake Project
Support Documentation for
Nutrient Load and Eutrophication
Model
1. INTRODUCTION
This report describes the technical basis for modeling of existing and future nutrient loads and
their impact in the proposed Randleman Lake. Results of this modeling are described in the
accompanying Randleman Lake Nutrient Reduction Strategy and Implementation Plan (February
1998).
Initial modeling of potential eutrophication within Randleman Lake was presented in the Draft
EIS (Black & Veatch 1990). For the development of the Nutrient Reduction Strategy, this
application was thoroughly reviewed by Tetra Tech, and revised and corrected in a number of
respects, as documented in this report.
2. LAKE EUTROPHICATION MODEL
Black & Veatch selected the U.S. Army Corps of Engineers' BATHTUB model (Walker 1987)
to represent nutrient and eutrophication conditions within Randleman Lake in response to current
and future land use conditions, and contracted with Walker to develop a spreadsheet application
of the model for Randleman Lake, driven by 59 years of rainfall/runoff data. The BATHTUB
model is designed to facilitate application of empirical eutrophication models to
morphometrically complex reservoirs. The program performs water and nutrient balance
calculations in a steady-state, spatially segmented hydraulic network that accounts for advective
transport, diffusion, and nutrient sedimentation. Eutrophication-related water quality conditions
are expressed in terms of total phosphorus, total nitrogen, chlorophyll a, transparency, organic
Randleman Lake Nutrient Load and Eutrophication Model I
Tetra Tech, Inc. February 1998
nitrogen, non-orthophosphate phosphorus, and hypolimnetic oxygen depletion rate. These
conditions are predicted using semiempirical relationships developed and tested on a wide range
of reservoirs (Walker 1985). The model can also simulate mass balances of arbitrary
conservative substances (such as magnesium or chloride).
Mass balances are computed in BATHTUB at steady state over an appropriate averaging period.
Steady-state approximation means that only seasonal or annual average loads and lake conditions
are simulated, although the loads and conditions may change from year to year. In other words,
the model does not represent day-to-day changes in flow, loads, or nutrient concentrations.
Although this approach represents a compromise, it has proven effective in practice. Short-term
variations in lake conditions reflect variations in flow, including wind and weather effects, which
require complex and labor-intensive models; such effects tend to average out, however, over
longer time frames. Thus, annual or seasonal average conditions can be successfully predicted
using data that are insufficient for simulating day-to-day variability.
While BATHTUB takes a steady-state approach to variability in time, it can represent spatial
complexity. Within the model, a reservoir can be represented as a set of linked segments, with as
much detail as desired. Each segment is assumed to be laterally mixed, but the water column can
be represented as stratified into three layers (each of which is assumed to be of constant thickness
over the averaging period, in accordance with the model's steady-state assumptions). Exchanges
of constituents between adjacent segments can occur by advection and dispersive transport, both
of which are calculated by the model. The model includes several methods for representing
dispersive exchange.
BATHTUB also provides a variety of options for simulating nutrient sedimentation, including
several first- and second-order representations proposed in the literature, as well as methods
developed explicitly for BATHTUB. Also available are five submodels for chlorophyll a, which
depend variously on nitrogen, phosphorus, light, and flushing rate limitations, and three
candidate models relating Secchi depth (transparency) to chlorophyll a, turbidity, and nutrient
concentrations. BATHTUB thus provides a highly flexible tool for developing a semi-
empirical, annual-average analysis of nutrient concentrations and eutrophication. The model also
includes extensive diagnostics and capabilities for error analysis.
2.1 Black & Veatch Application
Black & Veatch implemented a modified version of the BATHTUB model, designed for
spreadsheet application. The spreadsheet model solution algorithms are fully compatible with
the full BATHTUB model, although only a limited set of the options contained in the full
BATHTUB model are implemented. For instance, the spreadsheet implementation models
phosphorus, but not nitrogen, and therefore cannot examine potential colimitation by nitrogen
and phosphorus on algal growth. BATHTUB error analysis capabilities are also not included in
the spreadsheet model. Comparison of results from the spreadsheet model and the full
BATHTUB model run with identical input confirms that the spreadsheet provides results
2 Randleman Lake Nutrient Load and Eutrophication Model
Tetra Tech, Inc. February 1998
40 consistent with the published version of BATHTUB, with minor differences due to numerical
roundoff.
The main advantage of the spreadsheet implementation is that it includes a Lotus macro that
allows calculating results over 59 years of annual input data on flows and phosphorus loads.
These input data are based on Black & Veatch's analysis of historical meteorology and U.S.
Geological Survey (USGS) gage records for the Randleman Lake watershed. The spreadsheet
model thus provides an estimate of the range of conditions expected in response to variations in
annual precipitation and flow. In contrast, obtaining such results would require preparation of 59
separate input files using the original BATHTUB model.
Black & Veatch conducted simulations for both current and predicted future land use in the
watershed. Randleman Lake was divided into six segments for the simulations, as shown in
Figure 1. In all cases, water treatment plant withdrawals from Randleman Lake were assumed to
occur from the Muddy Creek 2 segment. The upstream impoundments Oak Hollow Lake and
High Point Lake were also included in the simulation.
Black & Veatch's analysis of current conditions represented the High Point Eastside WWTP
with an average discharge of 10.5 million gallons per day (mgd), containing 4 milligrams per
liter (mg/1) total phosphorus, based on monthly monitoring data collected from January 1986
through December 1989. The base analysis of future conditions assumed that wastewater flow
rate increased to 16 mgd, the design capacity of the plant. Based on 59 years' simulation,
existing land use was predicted to result in growing season average concentrations in the Muddy
Creek 2 segment of between 12.6 and 13.3 pg/1 chlorophyll a, while between 1.1 and 1.3 percent
of individual days were predicted to have nuisance algal concentrations of greater than 40 pg/l.
For future land use (with the WWTP operating at current treatment levels), growing season algal
concentrations in Muddy Creek 2 were predicted to increase to a range of 13.6 to 13.9 µg/l, with
nuisance frequencies of 1.5 to 1.6 percent.
The modeling also examined several special cases: (1) sensitivity of the model to 50 percent
versus 30 percent orthophosphate content of total phosphorus in nonpoint runoff; (2) sensitivity
of the model to an assumption of non-algal turbidity of 0.4 versus 0.7 and 0.2; (3) reduction of
the concentration of phosphorus in wastewater effluent from 4000 µg/l to 1000 µg/l; (4)
reduction of concentration of phosphorus in wastewater effluent from 4000 pg/1 to 500 µg/l; and
(5) elimination of wastewater discharge to Randleman Lake. For these special cases, the full 59
years were not simulated. Instead, representative years were chosen-1957 and 1967 to represent
low flow, 1943 and 1953 for average flow, and 1960 and 1975 for high flow. Maximum impact
in different parts of the lake is estimated to occur at different flows. In general, 1967 and 1975
conditions appear to represent the full range of potential impacts. Average flows can be
represented by 1983 data, when rainfall and runoff were very close to long term averages in the
watershed.
•
Randleman Lake Nutrient Load and Eutrophication Model 3
Tetra Tech, Inc. February 1998

z
g
z
W
Q
W
o:
W

RANDLEMAN LAKE
Figure 1. Schematic Diagram of Segmentation for BATHTUB Model of Randleman Lake
Watershed (from Black & Veatch, 1990)
2.2 Review and Revisions to Eutrophication Modeling Assumptions

Because Randleman Lake has not yet been impounded, it is impossible to calibrate the reservoir
model application. It is therefore necessary to run the model with best reasonable assumptions.
Because model predictions are only as good as the assumptions regarding input parameters and
cannot be tested against actual data, a careful review of the assumptions made by Black &
Veatch is warranted. Key areas reviewed are (1) model averaging period, (2) dispersion and 48
WASTEWATER
TREATMENT PLANT
WATER TREATMENT
PLANT
4 Randleman Lake Nutrient Load and Eutrophication Model
Tetra Tech, Inc. February 1998
numeric stability, (3) model segmentation, (4) specification of algal response and nutrient
sedimentation models, and (5) estimates of nonpoint nutrient loading. These assumptions are
discussed below, and used as a basis for developing a revised eutrophication analysis.
Residence Time, Turnover Rates, and Averaging Periods
•
Reservoir response to nutrient loads is strongly affected by the rate at which the lake flushes or
"turns over." General specifications of reservoir volumes and morphometry are based on
engineering analysis. Water balance for the reservoir also appears likely to be accurate and is
based on analysis of 59 years of USGS gage data. The nutrient residence time, however, affects
the way in which the BATHTUB model should be implemented, and so requires checking.
The spreadsheet model does not provide calculation of residence times; however, these are
readily calculated using the full BATHTUB model. For conditions of future land use, with the
WWTP discharging at 16 mgd and water treatment plant withdrawals from the Muddy Creek 2
segment at 48 mgd, the residence time for water (hydraulic residence time) varies from 0.0046
year in Deep River 1 to 0.21 year in Muddy Creek 2 under 1975 high flow conditions, and from
0.013 to 0.44 year under 1967 low flow conditions.
Mass residence time for nutrients may be calculated as
mass residence time (yr) = nutrient mass in reservoir (kg) (1)
external nutrient loading ftlyr)
while the corresponding turnover ratio, which approximates the number of times that the nutrient
mass in the reservoir is displaced during the averaging period, is given by
length of averaging period (yr)
turnover ratio =
mass residence time (yr)
(2)
Phosphorus residence times depend on both flows and rates of nutrient losses to sedimentation.
Walker (1987) states:
Ideally, the turnover ratio should exceed 2.0. If the ratio is too low, then pool and
outflow water quality measurements would increasingly reflect loading conditions
experienced prior to the start of the averaging period, which would be especially
problematical if there were substantial year-to-year variations in loadings ...
Normally, the appropriate averaging period for water and mass balance
calculations would be 1 year for reservoirs with relatively long nutrient residence
times or seasonal (May-September) for reservoirs with relatively short residence
times.
•
Randleman Lake Nutrient Load and Eutrophication Model 5
Tetra Tech, Inc. February 1998
To select an averaging period for BATHTUB, the documentation suggests running both annual
and seasonal applications, then selecting seasonal averaging "if seasonal phosphorus turnover
ratio > 2"; otherwise, selecting annual averaging.
Implementing a seasonal (May-September) model requires calculation of flows and influent
concentrations for the seasonal period. This presents two problems: (1) Black & Veatch (1990)
have calculated flows using their proprietary BVYIELD model and a complex averaging
procedure taking data from four USGS gages as input, adjusted to account for the creation of
upstream impoundments during the period of gage record, and do not report seasonal flows; and
(2) tributary concentrations are developed from long-term average annual yields, adjusted for
total flow within a year (see below). Tetra Tech developed surrogate summer season flows for 3
years that represent the range of hydrologic response simulated by Black & Veatch - a dry year
(based on 1967), a wet year (based on 1975), and an average year (based on 1983 data). The
summer season flows were estimated by calculating the percentile rank of annual flows for these
years in the annual flow duration series, identifying the total flows for May through September
with the same rank in the monthly flow duration series, and apportioning these seasonal flows
among tributaries based on the fraction of annual flow associated with each tributary. Rather
than recreating the entire BVYIELD model, Tetra Tech based flow durations on gage data at
Deep River near Randleman (USGS gage 02099500), downstream of the High Point Eastside
WWTP, for 1971 (after closure of Oak Hollow Lake) to present. Incremental flow rate between
this gage and the proposed Randleman Dam was calculated by the same equation used by Black
& Veatch:
(46.0 - 5.1) . (flow at gage 02100500 - flow at gage 02099500) (3)
224
where gage 02100500 is the downstream USGS gage on Deep River at Ramseur and the
coefficients adjust for the portion of the incremental drainage area above the dam, less expected
reservoir surface area.
Precipitation and evaporation for the May-September period were calculated from data from the
first-order meteorological station at Greensboro Piedmont-Triad Airport, scaled to correspond to
whole-year results reported by Black & Veatch for the Randleman station. May-September
tributary concentrations were assumed to be equal to those used for the annual simulation.
Finally, a water balance calibration was undertaken to assess the approximate amount of
drawdown of the reservoir during a seasonal simulation. Drawdown can be significant during
dry years, and it increases the impacts of nutrient loads by decreasing the volume available for
dilution.
For future land use conditions with the WWTP discharging at current phosphorus concentrations,
the annual phosphorus turnover ratio (calculated using area-weighted concentrations) varies from
14 to 19 for the whole watershed and from 16 to 21 for Randleman Lake itself (excluding Oak
6 Randleman Lake Nutrient Load and Eutrophication Model
Tetra Tech, Inc. February 1998
Hollow and High Point Lakes). Turnover ratios calculated for Randleman Lake on a seasonal
40 basis range from 1.9 (dry year) to 3.2 (wet year).
These turnover ratios at first suggested that a seasonal model might be appropriate. Closer
examination revealed, however, that the high seasonal turnover ratio (and short seasonal
residence time) is due to the dominance of WWTP phosphorus input during the May-September
period. Without WWTP loads, the May-September phosphorus turnover ratio would range from
0.2 to 1.0, corresponding to residence times of about 0.4 to 2 years, and would indicate use of
annual averaging. The Randleman Lake watershed (without the WWTP input) would then be
similar to that of many other North Carolina reservoirs, in which nonpoint nutrient loads occur
predominantly during winter-spring flows, which essentially flush out the reservoir and reset
conditions, leading to very low annual mass residence times, but high May-September mass
residence times. The calculated higher seasonal turnover ratios are due to the WWTP, which is
essentially a steady source, and thus there is not a need to modify the averaging period to limit
the influence of changing conditions prior to the start of simulation. Seasonal averaging will also
be inappropriate for the Muddy Creek arm, which is dominated by spring inflows, so results of a
seasonal BATHTUB application will be of limited value for comparing water quality at the
candidate water intake locations. Finally, data on external flows and loads appear considerably
less precise for seasonal as compared to annual simulations. Use of annual averaging is thus
appropriate for general simulation, although seasonal predictions should also be checked and
compared because they provide information on segment-to-segment flow patterns during the dry
period.
Dispersion and Numeric Stability
In the BATHTUB model a reservoir is divided into segments. Exchange between segments can
be by advection or dispersion, but constituents within segments are assumed to be laterally
mixed. A discontinuity in concentration will thus exist between adjacent segments, which leads
to numeric or artificial dispersion that is a consequence of model segmentation. Excessive
numeric dispersion can lead to instability in the model solution. Walker (1987) recommends
holding numeric dispersion less than longitudinal dispersion estimated by the method of Fischer
et al. (1987). This is achieved when the following condition holds:
L < 200 • W Z . Z -0.14 (4)
where L is the segment length (km), W is the mean top width (surface area divided by length,
km), and Z is the mean depth (m).
In the model segmentation presented by Black & Veatch, this length constraint is violated in two
segments - Deep River 1 and Muddy Creek 1. For instance, Deep River 1 has a segment length
of 7.1 km, but the Fischer length constraint is 0.731 km. Within these long and narrow
headwaters segments, however, transport is dominantly advective and longitudinal dispersion has
an insignificant effect on concentrations in segments downstream. Simply turning off dispersion
0
Randleman Lake Nutrient Load and Eutrophication Model 7
Tetra Tech, Inc. February 1998
for these segments results in no change in predictions at the water supply intake locations. The
length constraint is met in all other segments. Therefore, the existing segmentation grid is not
compromised by excessive numeric dispersion.
Model Segmentation
Although the model segmentation is acceptable in terms of dispersion calculations, it is not ideal
for comparison of alternative water intake locations. Because BATHTUB computes segments as
laterally averaged, concentration estimates are most representative of segment midpoints. Black
and Veatch (1990) considered only withdrawals from the Muddy Creek arm and set up the
Muddy Creek 2 segment so that the proposed intake is approximately centered in this segment.
Black & Veatch did not design segmentation to assess concentrations at the currently proposed
water intake location on Deep River. The Deep River intake location is at the downstream end of
Black & Veatch's Deep River 3 segment (Figure 2), and predictions for Deep River 3 will
overestimate expected chlorophyll a concentration at this intake because the center of this
segment is much nearer the WWTP phosphorus source than is the intake location.
It is also questionable whether Black & Veatch's segmentation will correctly represent reservoir
flow patterns. As shown in Figure 2, Muddy Creek 2 and Deep River 3 share an open water
boundary. Yet, the model flow network (Figure 1) connects both of these segments not to one
another but to the Dam Area segment. The Dam Area segment is, however, separated from
upstream segments by the constriction of the U.S. 220 bridge. It is unreasonable to assume that '
flow between Deep River 3 and Muddy Creek 2 occurs only via the Dam Area. Water
withdrawals from either segment should cause direct backflow from the adjacent segment.
To resolve these issues, model segmentation of the reservoir was revised. First, the Deep River 3
segment was subdivided into Deep River 3A and Deep River 313, with the latter segment
representing conditions near the proposed intake (Figure 3). The last half-kilometer of the old
Deep River 3 segment was moved to Muddy Creek 2, so that Muddy Creek 2 occupies the whole
width of the river immediately upstream of the U.S. 220 bridge. The revised flow network is
shown in Figure 4.
14
8 Randleman Lake Nutrient Load and Eutrophication Model
Tetra Tech, Inc. February 1998
•
REDDICKS
` CREEK
` HICKORY
HIGH POINT DEEP CREEK
' RIVER
RICHLAND CREEK
r Np
River 1 ___, `
GUILFORD COUNTY 7-
RANDOLPH '
COUN
N ` Deep
ARCHDALE River 2
` MUDDY 40 ? ''-
` CREEK
WATERSHED` Deep
BOUNDARY ` River 3
Muddy k *?Creek 1
2 miles
` Muddy rb
Creek 2
Figure 2
° . M x. `
BATHTUB Segmentation Used by Black & Veatch ` us 220"
3,: Candidate wafer Intake locations f?Dann
earM
BASE MAP SOURCE: 'BLACK AND VEATCH, WATER SUPPLY ALTERNATIVES ASSESSMENT (SEPTEMBER 1991) RAN D LEMAN
0
Randleman Lake Nutrient Load and Eutrophication Model 9
Tetra Tech, Inc. February 1998
REDDICKS
` CREEK
` HICKORY
J HIGH POINT DEEP CREEK
RIVER
?
RI
y?-" RICHLAND CREEK
` Deep
River 1
?rrrr
GUILFORD COUNTY
7 ....,..
??- RANDOLPH COON Deep
N ` River 2
ARCHDALE ?
??--MUDDY
\ CREEK
` ?J\ Deep `?=
WATERSHED `? mow 1 RNer 3A
BOUNDARY
Muddy'
Creek 1 ?t Deep
? 2 miles ? River 3B '
Muddy
Creek 2'
Figure 3 '
Revised BATHTUB Segmentation for Randleman Lake ` US 220 ,
mom f
if$ Candidate water Intake locations / Near AM
BASE MAP SOURCE: 'BLACK AND VEATCH, WATER SUPPLY Dam
ALTERNATIVES ASSESSMENT" (SEPTEMBER 1991) ` RAN D LE MAN
10 Randleman Lake Nutrient Load and Eutrophication Model

.7
Tetra Tech, Inc.
February 1998
HIGH POINT EASTSIDE
WASTEWATER
TREATMENT PLANT
EXISTING HIGH POINT
WATER TREATMENT
PLANT
•
Figure 4. Schematic Diagram of Revised Segmentation for BATHTUB Model of
Randleman Lake
Algal Response and Nutrient Sedimentation Models
•
BATHTUB contains options for seven different nitrogen and phosphorus sedimentation models
and for four different models for chlorophyll a (algal) response. The sedimentation models
determine the rate at which nutrients are lost from the water column (and thus implicitly include
reduction and degassing of nitrogen as well as true sedimentation), whereas the chlorophyll a
model controls the simulation of algal response to nutrient concentrations.
Randleman Lake Nutrient Load and Eutrophication Model 11
DEEP RIVER INTAKE,
NEW WATER
TREATMENT PLANT
Tetra Tech, Inc. February 1998
Black & Veatch chose to represent chlorophyll a response by BATHTUB Model 2, which bases
predictions on phosphorus, light availability, and flushing rate. For this reason, the spreadsheet
simulation model does not include the nitrogen mass balance. Model 2 predicts average
chlorophyll a (in µg/1) through
P 1.37
chlorophyll a = Kc - 4.88 P 1.37 (5)
1 + 0.025 4.88 • G (1 + G•a)
where
K, = calibration factor,
P = total phosphorus concentration (µg/1),
G = kinetic factor defined as
G=Zm,., •(0.19+0.0042•F ),
a = non-algal turbidity (m-'),
Z,,,;x = mean depth of the segment mixed (surface) layer (m), and
F,. = summer growing season flushing rate (yr'), defined as
(Inflow - Evaporation)/Volume.
This model is applicable where nitrogen is not limiting on algal growth. Walker's (1987) general
guidelines for application of this model are (1) Ni IPO„h ratio of inorganic nitrogen to ortho-
phosphate concentration greater than 7, and (2) (N-150)/P, the ratio of total nitrogen
concentration minus 150 pg/1 to total phosphorus concentration greater than 12. These
conditions are not always met. For instance, in the Black & Veatch simulation for future land
use and 1975 flows with the WWTP in place, NiIP,,,,h is estimated to be less than 7 in the Deep
River 1 and Deep River 2 segments, while (N-150)/P is estimated to be less than 12 in the Deep
River 1, Deep River 2, and Deep River 3 segments.
Accordingly, it is preferable to represent algal response using BATHTUB Model 1, which
accounts for both phosphorus and nitrogen limitation and is of general applicability. In this
model, chlorophyll a is predicted from
X 1.33
P"
chlorophyll a = Kc • 4.31 6
X1.33 ( )
1 + 0.025 • P" - G1 (1 + G1•a)
4.31
12 Randleman Lake Nutrient Load and Eutrophication Model
Tetra Tech, Inc. February 1998
0
40
0
where the new variables are
X,,,, =composite nutrient concentration (µg/1), calculated as
X =
pn
1 + 144
P' (N - 150)'
G, = kinetic factor defined as GI = ; ,, • (0.14 + 0.0039•F ), and
N = total nitrogen concentration (µg/1).
(7)
For phosphorus sedimentation, the Black & Veatch application uses BATHTUB Model 1. This
is a second-order decay model recommended for general application in Walker (1987), in which
total phosphorus loss is expressed empirically, based on Walker's analysis of the Corps of
Engineers reservoir data, as
S = K • 0.17 QS Pa
Qs + 13.3
where
(8)
S = empirical sedimentation or net removal rate (µg/l-yr),
K = calibration parameter reflecting deviations from the average of the base data
set used to develop the BATHTUB model, and
P" = inflow available phosphorus, defined as 0.33 x inflow total P concentration
plus 1.93 x inflow ortho-P concentration.
This model includes an empirical adjustment for the greater biological activity associated with
the ortho-phosphate fraction of total load. Walker offers various alternative sedimentation
models, but these are not recommended for application to series of linked reservoirs.
Accordingly, this sedimentation model is appropriate for use in Randleman Lake. The
corresponding second-order decay model was also adopted for simulation of nitrogen
sedimentation.
3. WATERSHED MODEL
Black & Veatch (1990) used a loading factor type approach for estimating annual flows and
nutrient loads to each of the model segments. This is not a full simulation of watershed
processes, but is more sophisticated than simple export coefficients (average annual loading
rates) because year-to-year variability in precipitation and flow are accounted for. Simulations
Randleman Lake Nutrient Load and Eutrophication Model 13
Tetra Tech, Inc. February 1998
conducted for the Nutrient Reduction Strategy are based on a modification and refinement of the
method used by Black & Veatch. The watershed model consists of two parts: representation of
runoff and nonpoint nutrient loading.
3.1 Rainfall/Runoff Model
Total annual runoff volume from a subwatershed, Qt, can be partitioned into two components,
surface and subsurface runoff. If runoff is given as a depth per year, the total annual runoff
volume from a subwatershed is
Qt = RI.A = RS•A + Rb•A
(9)
where R, is total runoff depth, RS is surface runoff depth, Rb is subsurface or baseflow runoff
depth, and A is area of the subwatershed. Partitioning into surface and subsurface components is
needed to drive the nutrient loading model.
Black & Veatch applied their BVYIELD model to available gage data to calculate total runoff,
R„ under existing conditions for each subwatershed. They then estimated the surface runoff
component (following CDM 1989) as
RS = P•0.75•I + P•0.11 •(1 -1) (10)
where P is the annual precipitation depth, I is the fraction of impervious surface cover within the
watershed, and 0.11 is a runoff factor for pervious surfaces obtained from typical runoff per unit
rainfall weighted over the percentage of Type B and Type C soils within the entire Randleman
Lake watershed. Note that the factor 0.75 for runoff from impervious surfaces appears to be
incorrect, and CDM (1989) used a more commonly accepted fraction of 0.95. Black & Veatch
then calculated baseflow as the difference between measured total runoff and estimated surface
runoff:
Rb = Rt - RS (11)
This approach leads to potentially inconsistent results. First, because RS is calculated from an
approximate empirical relationship while R, is based on gage data, for some low flow years and
subwatersheds the calculated value of RS was greater than R„ leading to a negative estimate of
baseflow. Black & Veatch compensated for this effect by assuming that RS was the smaller of the
estimated value and Rt. This correction, however, leads to a second undesirable effect: when the
calculated RS is greater than R, in low flow years the result is that all flow is predicted to occur by
surface pathways, with no baseflow. This is the opposite of what is expected for low flow years:
during drought conditions a larger than average percentage of precipitation will infiltrate into soil
and streamflow will be maintained primarily by baseflow. As nutrient concentrations are
generally higher in surface runoff, this leads to an overestimate of nutrient loading during low
flow conditions.
14 Randleman Lake Nutrient Load and Eutrophication Model
Tetra Tech, Inc. February 1998
A complete separation of surface and subsurface components on an annual basis would require
detailed rainfall-runoff modeling on a continuous basis, which was beyond the scope of the
current project. It was, however, desired to use more realistic estimates of baseflow which avoid
the bias inherent in assuming that all flow during drought conditions is by surface pathways. We
therefore made an ad hoc assumption that baseflow constitutes 50% of the total flow derived
from impervious areas up to total of 15" depth. Flow from impervious areas in excess of 15"
was assumed to be entirely by surface pathways.
The revision starts from the premise that values of total runoff depth, R,o, calculated by Black &
Veatch from gage data are correct. The surface component R,O is then partitioned into separate
runoff depths from impervious and pervious areas, RIO and Rpo. In this notation the subscript "0"
is used to indicate existing conditions. The resulting estimated flow components for existing
conditions are then given by
RIO = min (Pr-10-0.95, RIO)
RbO = min ((TAO-RI012, 7.5)
(12)
RPn = RIO - RIO - RbO
RIO = RPn + RIO
Runoff is expected to change under future land use conditions, due to increase in impervious
surface coverage. Black & Veatch apparently estimated future runoff based on scaling up the
surface runoff component by the estimated increase in impervious surface area. The future
runoff component estimates are subject to the same limitations as indicated above for partitioning
of existing flow. In addition, the Black & Veatch approach neglects the fact that baseflow will
likely be decreased as imperviousness increases. Given an estimate of future impervious surface
fraction, I,, we estimated the flow components under future land use conditions (indicated by
subscript "I", as follows:
RP1 = RPO ' (1 -I,)/(1 -Io)
Rb1 - RbO ' RP1 /RPn
R11 = P - 1l • 0.95 (13)
RII - RPl + R11
RI, - RI/ + Rbl
A final error was detected in the Black & Veatch spreadsheet application: the runoff depths are
applied over the entire area of a subwatershed, including the areas which will be part of the
proposed Randleman Lake. Because BATHTUB accounts for precipitation input directly, this
amounts to double counting of flow for the lake surface area.
40
Randleman Lake Nutrient Load and Eutrophication Model 15
Tetra Tech, Inc. February 1998
3.2 Nonpoint Nutrient Loading Model
Black & Veatch (1990) estimated nonpoint load rates based on export coefficients (lb-acre/yr),
largely derived from studies of small, single-land-use Piedmont basins in northern Virginia.
These are the same export coefficients used by CDM (1989) in the watershed studies of Oak
Hollow and City Lake Watersheds, which constitute the upper part of the watershed for the
proposed Randleman Lake. CDM compiled these coefficients from a variety of sources, but cites
as primary references NVPDC (1979) and Hartigan et al. (1983), in which loading factors were
developed through calibration of a nonpoint runoff model.
The northern Virginia export coefficients represent annual average delivery of load at the scale of
6- to 150-acre watersheds. Black & Veatch required yearly estimates of average stream
concentrations to apply the BATHTUB model to a variety of flow conditions. Year to year
variability in concentration is assumed to be due to variations in the relative contributions of
surface runoff and baseflow. To represent this, Black & Veatch first converted the reported long-
term average annual phosphorus load factor to an event mean concentration and calculated an
overall event mean stormwater concentration, C,,, for each tributary basin. This is considered to
be a constant. Total runoff concentration, C„ in any given year is then calculated as a weighted
average of concentrations in surface stormflow and baseflow:
R
Cl = S (CS - Q + Cb (14)
RI
where Ch is the concentration in baseflow. Black & Veatch (1990) present calculated annual
series of estimated phosphorus concentrations by subwatershed in their Appendix B. Annual
load series for nitrogen are not presented by Black & Veatch, but can be readily calculated using
the same methodology and data contained in their Tables IV-5 and IV-7.
Black & Veatch assumed a constant baseflow concentration. For phosphorus, the baseflow
concentration was assumed to be 35 ppb under existing conditions, and 80 ppb under future land
use conditions. We accepted these concentrations as reasonable estimates. However, an increase
under future conditions to 80 ppb was assumed to apply only in those subwatersheds for which
significant additional development was predicted. For nitrogen we assumed existing baseflow
concentrations of 1000 ppb, with an increase in highly-developed areas under future conditions
to 1500 ppb, based on experience in the Falls Lake and Cane Creek watersheds.
Watershed Delivery Ratio
One problem in applying the Hartigan load factors is that they do not account for attenuation of
load during transport through larger watersheds. Watershed areas draining to segments defined
for the Randleman Lake BATHTUB model range in size up to 78.8 km' (19,470 acres), versus
150 acres or less for the northern Virginia studies. Within a larger watershed, substantial '
16 Randleman Lake Nutrient Load and Eutrophication Model
Tetra Tech, Inc. February 1998
trapping of nutrients can occur. This is particularly important for phosphorus, which tends to
sorb to sediment and has a relatively insignificant baseflow component. Nitrogen, which is less
particle-reactive and has a large baseflow component, is less likely to be trapped, although losses
of mass can occur due to uptake by vegetation and denitrification by microbes.
For phosphorus, an approximate correction for basin scale may be made by assuming that
transport is primarily associated with sediment and considering the sediment delivery ratio (DR).
The DR indicates the portion of eroded soil within a watershed that is carried to the watershed
mouth. The dependence of DR on watershed area (for primarily rural watersheds) is summarized
graphically by Vanoni (ASCE 1975) for watersheds of size 1 km2 and larger. The graphical
relationship is closely approximated by the relationship
Log 10(DR) = -0.279 Log 10(A) - 0.376 (15)
in which A is watershed area expressed in square kilometers. If the CDM/Hartigan factors are
assumed to be approximately correct at a scale of 1 km2, estimates of percent phosphorus
delivered from larger watersheds may then be calculated by multiplying by the factor
10-0.279 logio(A)
(16)
For instance, for a watershed of 50 km2, this would suggest reducing phosphorus delivery by
multiplying by a factor of 0.407. Direct use of the CDM/Hartigan factors without accounting for
watershed trapping is therefore likely to result in an overestimate of total nonpoint phosphorus
delivery.
Equation (16) should not be applied directly to the loading factors used for Randleman Lake for
two reasons: (1) the area draining to each lake segment is not a single drainage, but actually
consists of a number of separate, smaller drainages; and (2) the Vanoni relationship is not valid
for highly developed watersheds in which connected impervious areas and stormwater
conveyances increase the delivery of sediment. To correct for these potential sources of error
two modifications were made. First, it was assumed that no watershed reduction of loading
factor rates occurs in runoff from highly developed areas, and reduction factors were only
applied to areas with a less-developed or rural character. Second, an analysis was made to
determine the approximate number of major constituent subwatersheds contained within the
drainage area of a given lake segment and the reduction factor altered accordingly. For instance,
if an areas was determined to consist of approximately 3 drainages, Equation (16) would be
modified to 10-0.279 log (A/3) Assumptions used to calculate delivery ratios for existing and future
conditions are summarized in Table 1 below. The net effect is that delivery ratios are expected to
increase under future conditions for most lake segments.
0
Randleman Lake Nutrient Load and Eutrophication Model 17
Tetra Tech, Inc. February 1998
Table 1. Assumptions Used to Calculate Delivery Ratios for
Existing and Future Conditions
Lake Segment Existing Conditions Future Conditions
Oak Hollow 100 % delivery from High Point, 2 100% delivery from all areas.
subwatersheds each for Guilford
and Forsyth Co. jurisdictions.
City Lake 100% delivery from all areas. 100% delivery from all areas.
Deep River 1 100% delivery from urban land 100% delivery from urban land
uses; 2 subwatersheds for rural uses; 2 subwatersheds for rural
land uses. land uses.
Deep River 2 3 subwatersheds. 100 % delivery from urban land
uses; 3 subwatersheds for rural
land uses.
Deep River 3 3 subwatersheds. 3 subwatersheds.
Muddy Creek 1 3 subwatersheds. 100% delivery from urban land
uses; 2 subwatersheds for rural
land uses.
Muddy Creek 2 3 subwatersheds. 3 subwatersheds.
Near Dam 3 subwatersheds. 100% delivery from Randleman
jurisdiction; 3 subwatersheds for
remaining area.
Organic and Inorganic Fractions
The specification of organic and inorganic fractions of nutrients is also an important factor in
BATHTUB simulation, since it helps determine the availability of nutrients to algae and the rate
of sedimentation losses. The loading factors give total phosphorus and total nitrogen only.
Black & Veatch assumed that all phosphorus discharged from the WWTP was in the form of
orthophosphate, while 30 percent of the phosphorus in storm runoff and baseflow was
orthophosphate. Analysis of USGS gage data for studies of the Falls Lake Watershed and Cane
Creek Watershed (Butcher et al. 1995, 1996) suggests that 30 percent is probably too low. For
instance, the orthophosphate fraction in Eno River and Little River in Durham is around 45
percent on a flow-weighted basis. For smaller streams in the Cane Creek watershed, the average
is around 50 percent. On the other hand, it is unlikely that the phosphorus load from the WWTP
is 100 percent orthophosphate, and some conversion to organic forms by bacteria and plankton is
expected within the stream reach between the discharge point and the proposed lake pool. Based
on recent experience with Durham dischargers and analysis of phosphorus species reported by
18 Randleman Lake Nutrient Load and Eutrophication Model
Tetra Tech, Inc. February 1998
NCDEM (1994) for 1992-93 at station RL4, in Deep River just below the WWTP discharge, an
estimate of around 75 percent orthophosphate in the WWTP effluent as delivered to the lake
appears more reasonable.
For nitrogen (not simulated by Black & Veatch), it is reasonable to assume that the baseflow
component from ground water is largely inorganic nitrogen, while surface runoff contains both
inorganic and organic nitrogen. Part of the inorganic nitrogen will be converted to organic forms
during delivery in the stream, and the inorganic fraction is difficult to estimate without
monitoring data. Fortunately, the model predictions of chlorophyll a response are not very
sensitive to the inorganic fraction of nonpoint nitrogen. Accordingly, the inorganic fraction is
simply estimated as a first approximation in Tetra Tech's simulations as 50 percent of the part of
nitrogen concentration attributable to surface runoff.
4. APPLICATION
The revised watershed model has been incorporated into a spreadsheet with dynamic links to
spreadsheets which estimate future land use conditions (see Appendix in the Nutrient Reduction
Strategy). This enables rapid evaluation of alternative management strategies and provides a
modeling tool which can be readily updated. The spreadsheet produces an input file for the COE
BATHTUB model, which predicts eutrophication response. Results are presented in the Nutrient
Reduction Strategy.
Sample BATHTUB input files for current land use and low flow, high flow, and average flow
conditions are appended.

Randleman Lake Nutrient Load and Eutrophication Model 19
Tetra Tech, Inc. February 1998
0
5. REFERENCES
ASCE. 1975. Sedimentation Engineering. V.A. Vanoni (ed.). American Society of Civil Engineers,
New York.
Black & Veatch. 1990. Water Quality and Quantity Studies to Support Randleman Lake Environmental
Impact Statement, December 1, 1990. Prepared for Piedmont Triad Regional Water Authority.
Butcher, J., T. Clements, A. Beach, K. Brewer, D. Korn, N. Archambault, P. Kellar and G. Pesacreta.
1995. Falls Lake Watershed Study, Final report. Prepared for The North Carolina Department of
Environment, Health, and Natural Resources. The Cadmus Group, Durham, NC.
Butcher, J., T. Clements, K. Brewer, A. Werner, D. Korn, J. Carey, N. Archambault, S. Coffey, D. Line
and G. Pesacreta. 1996. Cane Creek Reservoir Watershed Study, Draft report. Prepared for Orange
Water and Sewer Authority. The Cadmus Group, Durham, NC.
CDM. 1989. Watershed Management Study: Oak Hollow and City Lake Watersheds. Prepared for City
of High Point and Guilford County. Camp Dresser & McKee, Raleigh, NC.
Fischer, H.B., E.J. List, R.C.Y. Koh, J. Imberger and N.H. Brooks. 1979. Mixing in Inland and Coastal
Waters. Academic Press, New York.
• Hartigan, J.P., T.F. Quasebarth, and E. Southerland. 1983. Calibration of NPS model loading factors. J.
Environ. Eng.-ASCE 109(6): 1259-1272.
NCDEM. 1994. Water Quality Monitoring Data for Waters in the Upper Deep River Area, July 28,
1992 - October 7, 1993. North Carolina Division of Environmental Management, Water Quality Section,
Environmental Sciences Branch, Raleigh, NC.
NVPDC. 1979. Guidebook for Screening Urban Nonpoint Pollution Management Strategies. Prepared
for Metropolitan Washington Council of Governments by Northern Virginia Planning District
Commission.
Walker, W.W., Jr. 1987. Empirical Methods for Predicting Eutrophication in Impoundments.
Report 4-Phase III: Applications Manual. U.S. Army Corps of Engineers Technical Report E-81-9.
U.S. Army Waterways Experiment Station, Environmental Laboratory, Vicksburg, MS.
Walker, W.W., Jr. 1985. Empirical Methods for Predicting Eutrophication in Impoundments.
Report 3-Phase II: Model Refinements. U.S. Army Corps of Engineers Technical Report E-81-9. U.S.
Army Waterways Experiment Station, Environmental Laboratory, Vicksburg, MS.
0 Randleman Lake Nutrient Load and Eutrophication Model 21
Tetra Tech, Inc. February 1998
0
6. BATHTUB 1"UT FILES
Randleman Lake, Existing Land Use, Low Flow
PO S LABEL -------------------------- >
1 0 LIST INPUTS
2 1 HYDRAULICS & DISPERSION
3 2 GROSS WATER & MASS BALANCES
4 2 DETAILED BALANCES BY SEGMENT
5 2 SUMMARIZE BALANCES BY SEGMENT
6 1 COMPARE OBS & PREDICTED CONCS
7 1 DIAGNOSTICS
8 1 PROFILES
9 2 PLOTS
10 0 SENSITIVITY ANALYSIS
00
MO S LABEL----------------->
1 0 CONSERVATIVE SUBSTANCE
2 1 PHOSPHORUS BALANCE
3 1 NITROGEN BALANCE
4 1 CHLOROPHYLL-A
5 1 SECCHI DEPTH
6 1 DISPERSION
7 1 PHOSPHORUS CALIBRATION
8 1 NITROGEN CALIBRATION
9 0 ERROR ANALYSIS
00
IV NAME --->ATM--->CV---- >AVAIL->
1 CONSERV .0 .00 .00
2 TOTAL P 30.0 .50 .33
3 TOTAL N 1200.0 .50 .59
4 ORTHO P 15.0 .50 1.93
5 INORG N 600.0 .50 .79
00
ID LABEL ------------------ >MEAN----- >CV---- >
1 PERIOD LENGTH YRS 1.000 .000
2 PRECIPITATION M .916 .000
3 EVAPORATION M .896 .000
4 INCREASE IN STORAGE M .000 .000
5 FLOW FACTOR 1.000 .000
6 DISPERSION FACTOR 1.000 .700
7 TOTAL AREA KM2 .000 .000
8 TOTAL VOLUME HM3 .000 .000
00
ID T IS NAME ----------- >DAREA---- >FLOW----- >CV------- >
1 1 1 To Oak Hol 78.810 10.610 .100
2 1 2 To High Pt 75.820 11.750 .100
0 Randleman Lake Nutrient Load and Eutrophication Model 23
Tetra Tech, Inc. February 1998
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
00
ID
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
00
IS
1
2
3
4
5
6
7
8
9
00
IS
1
2
1 3 To Deep 1 89.740 12.540 .100
1 4 To Deep 2 75.220 10.510 .100
1 5 To Deep 3A 19.880 2.980 .100
1 6 To Deep 3B 5.740 .860 .100
1 7 To Mud 1 53.460 8.010 .100
1 8 To Mud 2 11.960 1.790 .100
1 9 To Dam 16.730 2.510 .100
4 2 WTP High Pt .000 19.360 .000
4 6 WTP New .000 8.300 .250
3 3 High Point WWTP .000 14.520 .000
3 1 Minors to Oak .000 .025 .000
3 3 Minors to Deep 1 .000 .048 .000
3 4 Minors to Deep 2 .000 .100 .000
3 5 Minors to Deep3a .000 .138 .000
3 7 Minors to Mud 1 .000 .044 .000
CONS-->CV-->TOTALP>
.0 .000 105.0
.0 .000 152.2
.0 .000 189.1
.0 .000 59.3
.0 .000 73.1
.0 .000 73.1
.0 .000 72.9
.0 .000 94.9
.0 .000 73.0
.0 .000 .0
.0 .000 .0
.0 .000 4000.0
.0 .000 5000.0
.0 .000 5000.0
.0 .000 5000.0
.0 .000 5000.0
.0 .000 5000.0
-V-->TOTALN>
.250 1459.8
.250 1427.5
.250 1875.4
.250 1327.1
.250 1740.7
.250 1740.7
.250 1448.7
.250 1857.6
.250 1822.5
.000 .0
.000 .0
.00020000.0
.00020000.0
.00020000.0
.00020000.0
.00020000.0
.00020000.0
-V-->ORTHOP>
.250 52.5
.250 76.1
.250 94.6
.250 29.7
.250 36.6
.250 36.6
.250 36.4
.250 47.5
.250 36.5
.000 .0
.000 .0
.000 3000.0
.000 3000.0
.000 3000.0
.000 3000.0
.000 3000.0
.000 3000.0
CV-->INORGN>CV-->
.250 878.0 .250
.250 808.8 .250
.250 938.1 .250
.250 849.6 .250
.250 1093.2 .250
.250 1093.2 .250
.250 926.8 .250
.250 1152.7 .250
.250 1148.4 .250
.000 .0 .000
.000 .0 .000
.00017000.0 .000
.00010000.0 .000
.00010000.0 .000
.00010000.0 .000
.00010000.0 .000
.00010000.0 .000
JO JG NAME ----------- >KP-->KN-->KC-->KS-->KO-->KD------- >
2 1 Oak Hollow 1.00 1.00 1.00 1.00 1.00 .000
3 2 High Point 1.00 1.00 1.00 1.00 1.00 .000
4 3 Deep 1 1.00 1.00 1.00 1.00 1.00 .000
5 3 Deep 2 1.00 1.00 1.00 1.00 1.00 1.000
6 3 Deep 3A 1.00 1.00 1.00 1.00 1.00 1.000
8 1 Deep 3B 1.00 1.00 1.00 1.00 1.00 1.000
8 3 Mud 1 1.00 1.00 1.00 1.00 1.00 .000
9 3 Mud 2 1.00 1.00 1.00 1.00 1.00 1.000
0 3 Dam 1.00 1.00 1.00 1.00 1.00 1.000
PERD>PREC>EVAP>STOR>LENG->AREA->ZMN--> ZMIX->CV--- >Z HYP->CV--- >
1.0 1.0 1.0 1.0 2.5 3.004 4.11 3.96 .00 1.99 .00
1.0 1.0 1.0 1.0 2.2 1.478 3.09 3.09 .00 1.77 .00
24 Randleman Lake Nutrient Load and Eutrophication Model
Tetra Tech, Inc. February 1998
• 3 1.0 1.0 1.0 1.0 7.1 .559 1.87 1.87 .00 3.98 .00
4 1.0 1.0 1.0 1.0 6.7 2.239 4.16 4.16 .00 3.98 .00
5 1.0 1.0 1.0 1.0 5.2 2.737 6.62 5.31 .00 3.98 .00
6 1.0 1.0 1.0 1.0 1.5 .789 6.62 5.31 .00 3.98 .00
7 1.0 1.0 1.0 1.0 5.2 .887 3.84 3.84 .00 3.98 .00
8 1.0 1.0 1.0 1.0 3.7 2.146 7.27 5.31 .00 3.98 .00
9 1.0 1.0 1.0 1.0 2.3 3.288 8.08 5.31 .00 3.98 .00
00
IS TURB->COND->TP- -->TN--->CH LA->SEC -->ORGN->PP--->HODV->MODV->
1 .40 .0 .0 0. 14.0 1 .20 0. .0 .0 .0
1 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
2 .28 .0 .0 0. 29.5 1 .00 0. .0 .0 .0
2 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
3 .40 .0 .0 0. .0 .00 0. .0 .0 .0
3 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
4 .40 .0 .0 0. .0 .00 0. .0 .0 .0
4 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
5 .40 .0 .0 0. .0 .00 0. .0 .0 .0
5 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
6 .40 .0 .0 0. .0 .00 0. .0 .0 .0
6 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
7 .40 .0 .0 0. .0 .00 0. .0 .0 .0
7 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
8 .40 .0 .0 0. .0 .00 0. .0 .0 .0
8 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
9 .40 .0 .0 0. .0 .00 0. .0 .0 .0
9 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
00
IT CAT1--->CAT2--- >CAT3--->CAT4--->
00
IC NAME ----------- >RLTNOFF->CONSER->TOTALP->TOTALN->ORTHOP->INORGN->
1 landusel .840 .0 248.1 1000.0 74.4 500.0
1 .00 .00 .00 .00 .00 .00
2 landuse2 1.050 .0 231.7 1000.0 69.5 500.0
2 .00 .00 .00 .00 .00 .00
3 landuse3 .810 .0 238.6 1000.0 71.6 500.0
3 .00 .00 .00 .00 .00 .00
4 landuse4 .780 .0 211.3 1000.0 63.4 500.0
4 .00 .00 .00 .00 .00 .00
00
IX NAME ----------- - >MEAN--->CV----- >
1 P DECAY RATE 1.000 .450
2 N DECAY RATE 1.000 .550
3 CHL-A MODEL 1.000 .260
4 SECCHI MODEL 1.000 .100
5 ORGANIC N MODEL 1.000 .120
6 TP-OP MODEL 1.000 .150
7 HODV MODEL 1.000 .150
8 MODV MODEL 1.000 .220
0 Randleman Lake Nutrient Load and Eutrophication Model

25
Tetra Tech, Inc. February 1998
9 BETA M2/MG .025 .000
10 MINIMUM QS .100 .000
11 FLUSHING EFFECT 1.000 .000
12 CHLOROPHYLL-A CV .570 .000
00
Randleman Lake, Existing Land Use, High Flow
PO S LABEL -------------------------- >
1 0 LIST INPUTS
2 1 HYDRAULICS & DISPERSION
3 2 GROSS WATER & MASS BALANCES
4 2 DETAILED BALANCES BY SEGMENT
5 2 SUMMARIZE BALANCES BY SEGMENT
6 1 COMPARE OBS & PREDICTED CONCS
7 1 DIAGNOSTICS
8 1 PROFILES
9 2 PLOTS
10 0 SENSITIVITY ANALYSIS
00
MO S LABEL----------------->
1 0 CONSERVATIVE SUBSTANCE
2 1 PHOSPHORUS BALANCE
3 1 NITROGEN BALANCE
4 1 CHLOROPHYLL-A
5 1 SECCHI DEPTH
6 1 DISPERSION
7 1 PHOSPHORUS CALIBRATION
8 1 NITROGEN CALIBRATION
9 0 ERROR ANALYSIS
00
IV NAME --->ATM--->CV---- >AVAIL->
1 CONSERV .0 .00 .00
2 TOTAL P 30.0 .50 .33
3 TOTAL N 1200.0 .50 .59
4 ORTHO P 15.0 .50 1.93
5 INORG N 600.0 .50 .79
00
ID LABEL ------------------ >MEAN----- >CV---- >
1 PERIOD LENGTH YRS 1.000 .000
2 PRECIPITATION M 1.686 .000
3 EVAPORATION M .896 .000
4 INCREASE IN STORAGE M .000 .000
5 FLOW FACTOR 1.000 .000
6 DISPERSION FACTOR 1.000 .700
7 TOTAL AREA KM2 .000 .000
8 TOTAL VOLUME HM3 .000 .000
00
ID T IS NAME ----------- >DAREA---- >FLOW- ---- >CV------- >
26 Randleman Lake Nutrient Load and Eutrophication Model

•
0 Randleman Lake Nutrient Load and Eutrophication Model 27
Tetra Tech, Inc.
February 1998
1 1 1 To Oak Hol 78.810 45.040 .100
2 1 2 To High Pt 75.820 52.380 .100
3 1 3 To Deep 1 89.740 54.020 .100
4 1 4 To Deep 2 75.220 45.280 .100
5 1 5 To Deep 3A 19.880 11.920 .100
6 1 6 To Deep 3B 5.740 3.440 .100
7 1 7 To Mud 1 53.460 32.050 .100
8 1 8 To Mud 2 11.960 7.170 .100
9 1 9 To Dam 16.730 10.030 .100
10 4 2 WTP High Pt .000 19.360 .000
11 4 6 WTP New .000 8.300 .250
12 3 3 High Point WWTP .000 14.520 .000
13 3 1 Minors to Oak .000 .025 .000
14 3 3 Minors to Deep 1 .000 .048 .000
15 3 4 Minors to Deep 2 .000 .100 .000
16 3 5 Minors to Deep3a .000 .138 .000
17 3 7 Minors to Mud 1 .000 .044 .000
00
ID CONS-->CV-->TOTALP>CV-->TOTALN>CV-->ORTHOP>CV-->INORGN>CV-->
1 .0 .000 101.3 .250 1435.5 .250 50.7 .250 884.4 .250
2 .0 .000 139.8 .250 1382.3 .250 69.9 .250 829.0 .250
3 .0 .000 145.0 .250 1624.9 .250 72.5 .250 955.8 .250
4 .0 .000 61.5 .250 1356.0 .250 30.8 .250 836.3 .250
5 .0 .000 81.9 .250 1911.5 .250 41.0 .250 1114.6 .250
6 .0 .000 81.9 .250 1911.5 .250 41.0 .250 1114.6 .250
7 .0 .000 78.4 .250 1514.4 .250 39.2 .250 916.1 .250
8 .0 .000 109.0 .250 2059.3 .250 54.5 .250 1188.6 .250
9 .0 .000 84.3 .250 2067.4 .250 42.2 .250 1192.6 .250
10 .0 .000 ..0 .000 .0 .000 .0 .000 .0 .000
11 .0 .000 .0 .000 .0 .000 .0 .000 .0 .000
12 .0 .000 4000.0 .00020000.0 .000 3000.0 .00017000.0 .000
13 .0 .000 5000.0 .00020000.0 .000 3000.0 .00010000.0 .000
14 .0 .000 5000.0 .00020000.0 .000 3000.0 .00010000.0 .000
15 .0 .000 5000.0 .00020000.0 .000 3000.0 .00010000.0 .000
16 .0 .000 5000.0 .00020000.0 .000 3000.0 .00010000.0 .000
17 .0 .000 5000.0 .00020000.0 .000 3000.0 .00010000.0 .000
00
IS JO JG NAME ----------- >KP-->KN-->KC-->KS-->KO-->KD------- >
1 2 1 Oak Hollow 1.00 1.00 1.00 1.00 1.00 .000
2 3 2 High Point 1.00 1.00 1.00 1.00 1.00 .000
3 4 3 Deep 1 1.00 1.00 1.00 1.00 1.00 .000
4 5 3 Deep 2 1.00 1.00 1.00 1.00 1.00 1.000
5 6 3 Deep 3A 1.00 1.00 1.00 1.00 1.00 1.000
6 8 1 Deep 3B 1.00 1.00 1.00 1.00 1.00 1.000
7 8 3 Mud 1 1.00 1.00 1.00 1.00 1.00 .000
8 9 3 Mud 2 1.00 1.00 1.00 1.00 1.00 1.000
9 0 3 Dam 1.00 1.00 1.00 1.00 1.00 1.000
00
IS PERD>PREC>EVAP>STOR>LENG->AREA->ZMN-->ZMIX->CV--- >ZHYP->CV--- >

Tetra Tech, Inc.
February 1998
1 1.0 1.0 1.0 1.0 2.5 3.004 4.11 3.96 .00 1.99 .00
2 1.0 1.0 1.0 1.0 2.2 1.478 3.09 3.09 .00 1.77 .00
3 1.0 1.0 1.0 1.0 7.1 .559 1.87 1.87 .00 3.98 .00
4 1.0 1.0 1.0 1.0 6.7 2.239 4.16 4.16 .00 3.98 .00
5 1.0 1.0 1.0 1.0 5.2 2.737 6.62 5.31 .00 3.98 .00
6 1.0 1.0 1.0 1.0 1.5 .789 6.62 5.31 .00 3.98 .00
7 1.0 1.0 1.0 1.0 5.2 .887 3.84 3.84 .00 3.98 .00
8 1.0 1.0 1.0 1.0 3.7 2.146 7.27 5.31 .00 3.98 .00
9 1.0 1.0 1.0 1.0 2.3 3.288 8.08 5.31 .00 3.98 .00
00
IS TURB->COND->TP--->TN--->CHLA->SEC-->ORGN->PP--->HODV->MODV->
1 .40 .0 .0 0. 14.0 1.20 0. .0 .0 .0
1 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
2 .28 .0 .0 0. 29.5 1.00 0. .0 .0 .0
2 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
3 .40 .0 .0 0. .0 .00 0. .0 .0 .0
3 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
4 .40 .0 .0 0. .0 .00 0. .0 .0 .0
4 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
5 .40 .0 .0 0. .0 .00 0. .0 .0 .0
5 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
6 .40 .0 .0 0. .0 .00 0. .0 .0 .0
6 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
7 .40 .0 .0 0. .0 .00 0. .0 .0 .0
7 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
8 .40 .0 .0 0. .0 .00 0. .0 .0 .0
8 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
9 .40 .0 .0 0. .0 .00 0. .0 .0 .0
9 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
00
IT CAT1--->CAT2--->CAT3--->CAT4--->
00
IC NAME ----------- >RLTNOFF->CONSER->TOTALP->TOTALN->ORTHOP->INORGN->
1 landusel .840 .0 248.1 1000.0 74.4 500.0
1 .00 .00 .00 .00 .00 .00
2 landuse2 1.050 .0 231.7 1000.0 69.5 500.0
2 .00 .00 .00 .00 .00 .00
3 landuse3 .810 .0 238.6 1000.0 71.6 500.0
3 .00 .00 .00 .00 .00 .00
4 landuse4 .780 .0 211.3 1000.0 63.4 500.0
4 .00 .00 .00 .00 .00 .00
00
IX NAME ------------ >MEAN--->CV----- >
1 P DECAY RATE 1.000 .450
2 N DECAY RATE 1.000 .550
3 CHL-A MODEL 1.000 .260
4 SECCHI MODEL 1.000 .100
5 ORGANIC N MODEL 1.000 .120
6 TP-OP MODEL 1.000 .150
28 Randleman Lake Nutrient Load and Eutrophication Model
Tetra Tech, Inc. February 1998
• 7 HODV MODEL 1.000 .150
8 MODV MODEL 1.000 .220
9 BETA M2/MG .025 .000
10 MINIMUM QS .100 .000
11 FLUSHING EFFECT 1.000 .000
12 CHLOROPHYLL-A CV .570 .000
00
Randleman Lake, Existing Land Use, Average Flow
PO S LABEL -------------------------- >
1 0 LIST INPUTS
2 1 HYDRAULICS & DISPERSION
3 2 GROSS WATER & MASS BALANCES
4 2 DETAILED BALANCES BY SEGMENT
5 2 SUMMARIZE BALANCES BY SEGMENT
6 1 COMPARE OBS & PREDICTED CONCS
7 1 DIAGNOSTICS
8 1 PROFILES
9 2 PLOTS
10 0 SENSITIVITY ANALYSIS
00
MO S LABEL----------------->
1 0 CONSERVATIVE SUBSTANCE
2 1 PHOSPHORUS BALANCE
. 3 1 NITROGEN BALANCE
4 1 CHLOROPHYLL-A
5 1 SECCHI DEPTH
6 1 DISPERSION
7 1 PHOSPHORUS CALIBRATION
8 1 NITROGEN CALIBRATION
9 0 ERROR ANALYSIS
00
IV NAME --->ATM--->CV---- >AVAIL->
1 CONSERV .0 .00 .00
2 TOTAL P 30.0 .50 .33
3 TOTAL N 1200.0 .50 .59
4 ORTHO P 15.0 .50 1.93
5 INORG N 600.0 .50 .79
00
ID LABEL ------------------ >MEAN----- >CV---- >
1 PERIOD LENGTH YRS 1.000 .000
2 PRECIPITATION M 1.101 .000
3 EVAPORATION M .947 .000
4 INCREASE IN STORAGE M .000 .000
5 FLOW FACTOR 1.000 .000
6 DISPERSION FACTOR 1.000 .700
7 TOTAL AREA KM2 .000 .000
8 TOTAL VOLUME HM3 .000 .000

• Randleman Lake Nutrient Load and Eutrophication Model 29
Tetra Tech, Inc. February 1!
00
ID T IS NAME ----------- >DAREA---- >FLOW----- >CV------- >
1 1 1 To Oak Hol 78.810 31.230 .100
2 1 2 To High Pt 75.820 31.580 .100
3 1 3 To Deep 1 89.740 37.150 .100
4 1 4 To Deep 2 75.220 31.140 .100
5 1 5 To Deep 3A 19.880 7.880 .100
6 1 6 To Deep 3B 5.740 2.270 .100
7 1 7 To Mud 1 53.460 21.180 .100
8 1 8 To Mud. 2 11.960 4.740 .100
9 1 9 To Dam 16.730 6.630 .100
10 4 2 WTP High Pt .000 19.360 .000
11 4 6 WTP New .000 8.300 .250
12 3 3 High Point WWTP .000 14.520 .000
13 3 1 Minors to Oak .000 .025 .000
14 3 3 Minors to Deep 1 .000 .048 .000
15 3 4 Minors to Deep 2 .000 .100 .000
16 3 5 Minors to Deep3a .000 .138 .000
17 3 7 Minors to Mud 1 .000 .044 .000
00
ID CONS-->CV-->TOTALP>CV-->TOTALN>CV-->ORTHOP>CV-->INORGN>CV-->
1 .0 .000 93.0 .250 1381.0 .250 46.5 .250 898.9 .250
2 .0 .000 127.4 .250 1337.0 .250 63.7 .250 849.2 .250
3 .0 .000 143.4 .250 1595.8 .250 71.7 .250 946.7 .250
4 .0 .000 56.4 .250 1194.0 .250 28.2 .250 845.6 .250
5 .0 .000 71.1 .250 1215.8 .250 35.5 .250 845.6 .250
6 .0 .000 71.1 .250 1215.8 .250 35.5 .250 845.6 .250
7 .0 .000 69.6 .250 1355.2 .250 34.8 .250 906.0 .250
8 .0 .000 91.8 .250 1296.9 .250 45.9 .250 886.6 .250
9 .0 .000 72.5 .250 1168.1 .250 36.3 .250 824.4 .250
10 .0 .000 .0 .000 .0 .000 .0 .000 .0 .000
11 .0 .000 .0 .000 .0 .000 .0 .000 .0 .000
12 .0 .000 4000.0 .00020000.0 .000 3000.0 .00017000.0 .000
13 .0 .000 5000.0 .00020000.0 .000 3000.0 .00010000.0 .000
14 .0 .000 5000.0 .00020000.0 .000 3000.0 .00010000.0 .000
15 .0 .000 5000.0 .00020000.0 .000 3000.0 .00010000.0 .000
16 .0 .000 5000.0 .00020000.0 .000 3000.0 .00010000.0 .000
17 .0 .000 5000.0 .00020000.0 .000 3000.0 .00010000.0 .000
00
IS JO JG NAME ----------- >KP-->KN-->KC-->KS-->KO-->KD------- >
1 2 1 Oak Hollow 1.00 1.00 1.00 1.00 1.00 .000
2 3 2 High Point 1.00 1.00 1.00 1.00 1.00 .000
3 4 3 Deep 1 1.00 1.00 1.00 1.00 1.00 .000
4 5 3 Deep 2 1.00 1.00 1.00 1.00 1.00 1.000
5 6 3 Deep 3A 1.00 1.00 1.00 1.00 1.00 1.000
6 8 1 Deep 3B 1.00 1.00 1.00 1.00 1.00 1.000
7 8 3 Mud 1 1.00 1.00 1.00 1.00 1.00 .000
8 9 3 Mud 2 1.00 1.00 1.00 1.00 1.00 1.000
9 0 3 Dam 1.00 1.00 1.00 1.00 1.00 1.000
30 Randleman Lake Nutrient Load and Eutrophication Moe
Tetra Tech, Inc. February 1998
-' 00
IS PERD>PREC>EVAP> STOR>LENG->AREA-> ZMN-->ZMIX->CV--->ZHYP->CV--->
1 1.0 1.0 1.0 1.0 2.5 3.004 4.11 3.96 .00 1.99 .00
2 1.0 1.0 1.0 1.0 2.2 1.478 3.09 3.09 .00 1.77 .00
3 1.0 1.0 1.0 1.0 7.1 .559 1.87 1.87 .00 3.98 .00
4 1.0 1.0 1.0 1.0 6.7 2.239 4.16 4.16 .00 3.98 .00
5 1.0 1.0 1.0 1.0 5.2 2.737 6.62 5.31 .00 3.98 .00
6 1.0 1.0 1.0 1.0 1.5 .789 6.62 5.31 .00 3.98 .00
7 1.0 1.0 1.0 1.0 5.2 .887 3.84 3.84 .00 3.98 .00
8 1.0 1.0 1.0 1.0 3.7 2.146 7.27 5.31 .00 3.98 .00
9 1.0 1.0 1.0 1.0 2.3 3.288 8.08 5.31 .00 3.98 .00
00
IS TURB->COND->TP- -->TN--->CHLA->SE C-->ORGN->PP--->HODV->MODV->
1 .40 .0 .0 0. 14.0 1.20 0. .0 .0 .0
1 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
2 .28 .0 .0 0. 29.5 1.00 0. .0 .0 .0
2 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
3 .40 .0 .0 0. .0 .00 0. .0 .0 .0
3 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
4 .40 .0 .0 0. .0 .00 0. .0 .0 .0
4 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
5 .40 .0 .0 0. .0 .00 0. .0 .0 .0
5 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
6 .40 .0 .0 0. .0 .00 0. .0 .0 .0
6 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
• 7 .40 .0 .0 0. .0 .00 0. .0 .0 .0
7 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
8 .40 .0 .0 0. .0 .00 0. .0 .0 .0
8 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
9 .40 .0 .0 0. .0 .00 0. .0 .0 .0
9 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
00
IT CAT1--->CAT2--- >CAT3--->CAT4--->
00
IC NAME ----------- >RUNOFF->CONSER->TOTALP->TOTALN->ORTHOP->INORGN->
1 landusel .840 .0 248.1 1000.0 74.4 500.0
1 .00 .00 .00 .00 .00 .00
2 landuse2 1.050 .0 231.7 1000.0 69.5 500.0
2 .00 .00 .00 .00 .00 .00
3 landuse3 .810 .0 238.6 1000.0 71.6 500.0
3 .00 .00 .00 .00 .00 .00
4 landuse4 .780 .0 211.3 1000.0 63.4 500.0
4 .00 .00 .00 .00 .00 .00
00
IX NAME ----------- - >MEAN--->CV----- >
1 P DECAY RATE 1.000 .450
2 N DECAY RATE 1.000 .550
3 CHL-A MODEL 1.000 .260
4 SECCHI MODEL 1.000 .100
40 Randleman Lake Nutrient Load and Eutrophication Model 31
Tetra Tech, Inc. February I S
5 ORGANIC N MODEL 1.000 .120
6 TP-OP MODEL` 1.000 .'150
7 HODV MODEL 1.000 .150
S' " MODV MODEL 1.000 .220
9 BETA M2/MG .025 .000
10 MINIMUM QS .100 .000
11 FLtJSHING EFFECT 1.000 .000
12 CHLOROPHYLL-A CV .570 .000
00
32 Randleman Lake Nutrient Load and Eutrophication Mot