20120285 Ver 1_Scoping Comments_20111122

BEVERLY EAVES PERDUE
GOVERNOR
STATE OF NORTH CAROLINA
DEPARTMENT OF TRANSPORTATION
TURNPIKE AUTHORITY
November 22 2011
Ms Polly Lespinasse
NC Department of Environment and Natural Resources
Division of Water Quality
Mooresville Regional Office
610 East Center Avenue — Suite 301
Mooresville NC 28115
EUGENE A CONTI 7R
SFCRFTARY
Ms Lespinasse
Thank you for your memorandum of September 19 in response to our request for comments on
the report titled Gaston East West Connector Indirect and Cumulative Effects Water Quality
Analysis — Draft (Atkins August 2011) (referred to in this letter as the Water Quality Analysis)
We offer the following in response to the questions and concerns raised in your letter
Protect Specific Comments
1 The analysis indicates notable increases between the 2035 No Build Analysis and the 2035
Build Analysis Increases in the amount of total phosphorus (TP) are expected in the
Catawba Creek (7 %) Lower Crowders Creek (5 5 %) Lake Wylie Catawba River (5 3 %) and
Beaverdam Creek Catawba River (5 3 %) hydrologic units (HUs) Increases in total nitrogen
(TN) are expected in the Catawba Creek (5 3 %) and Lake Wylie Catawba River (5 3 %) HUs
Additionally increases in annual runoff are expected in the Beaverdam Creek Catawba River
(8 73 %) Catawba Creek (7 97 %) and Lower Crowders Creek (7 28 %) HUs Catawba Creek
Lower Crowders Creek Lake Wylie and Beaverdam Creek are either on North or South
Carolinas 2010 303(d) list or have established TMDLs (total maximum daily loads) Catawba
Creek and Lake Wylie are listed for impaired biological integrity Lower Crowders Creek is
listed for impaired biological integrity throughout the reach and fecal coliform in some stream
sections DWQ is very concerned with the potential indirect and cumulative impacts to both
303(d) listed streams and non 303(d) listed streams throughout the study area that may result
from the construction of this road While Beaverdam Creek Catawba River is not currently on
the North Carolina 303(d) list it is expected to see an increase in TP TN and annual runoff
Increased pollutants in this HU as a result of the construction of this protect could result in
impairment necessitating its listing on the 303(d) list The NCTA is encouraged to investigate
opportunities with local governments to address the indirect and cumulative impacts to local
jurisdictional resources that may be incurred as a result of this protect
NORTH CAROLINA TURNPIKE AUTHORITY
1578 MAIL SERVICE CENTER RALEIGH N C 27699 1578
PHONE [phone] FAX [phone]
http / /www ncturnplke org

between the No Build and Build conditions was used to reallocate growth for the No Build
condition representing a different pattern of household and business location decision in the
absence of a Gaston East West Connector For complete technical information on the gravity
model equations refer to Section 2 4 2 of the Quantitative ICE Assessment
The NCDWQ requests written confirmation from each MPO that construction of the road or
any portion of the road was not included to the No Build analysis Based on the specific
methodology used for the Gaston East West Connector Quantitative ICE Assessment NCTA
does not believe additional written confirmation from the MPOs is necessary or applicable
The socioeconomic forecasts developed by the MPOs were used as the Build condition for
this analysis (unlike the Monroe Connector /Bypass where it was used as the No Build
condition) and documentation of the inclusion of the Garden Parkway explicitly in these
forecasts and MPO concurrence with this use is provided in the Quantitative ICE
Assessment as discussed above The gravity model methodology involves comparing
accessibility to individual TAZs for Metrolma model runs with and without the Garden
Parkway in order to allocate growth for the No Build condition So a No Build condition in
this approach inherently involves removing the Garden Parkway from the model to arrive at
the change in accessibility
3 Pages i and 33 of the Water Quality Analysis state that four of the five HUs with 303(d)
listed stream show decreases TSS under the Budd Scenario Based on Table 20 the
only 303(d) listed HU which shows a decrease in TSS is the Mill Creek — Lake Wylie HU
Decreases are seen in two other HUs (Fates Creek and Lake Wylie Catawba River) but
according to this document they are not 303(d) listed
• NCDWQ has identified an error in the water quality report The report should state that an
increase in TSS load is expected for 4 of the 5 HUs containing 303(d) listed waters The Mill
Creek Lake Wylie HU is the exception as the TSS loading rate was estimated to decrease by
1 0 percent in this HU The statement will be corrected in the final version of the report
General Comments
These general comments also were provided to NCTA in NCDWQ s comment letter on the Final
EIS (dated February 21 2011) and responses to these comments will be included in the ROD
1 In accordance with the Environmental Management Commission s Rules {15A NCAC
2H 0506(h)} mitigation will be required for impacts of greater than 150 linear feet to any
single perennial stream In the event that mitigation is required the mitigation plan shall
be designed to replace appropriate lost functions and values The NC Ecosystem
Enhancement Program may be available for use as stream mitigation
NCTA is working to identify and secure on site mitigation opportunities to proximity to the
project The NC Ecosystem Enhancement Program (EEP) has committed the Beaverdam
Creek mitigation project (letter dated July 11 2011 to be included in the ROD) The project
is in the fifth year of monitoring and is expected to deliver 13 534 6 stream mitigation credits
In June 2011 NCDOT acquired the Linwood Springs Golf Course property which will
prowde for stream restoration along Crowders Creek a 303(d) listed stream The golf course
property also contains several unnamed tributaries open water ponds and vegetated ditches
that drain surface water to Crowders Creek In addition NCTA is continuing to pursue other
adjacent parcels in this area as well as other onsite mitigation opportunities near the project
2 Future documentation including the 401 Water Quality Certification Application shall
continue to include an itemized listing of the proposed wetland and stream impacts with
corresponding mapping
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In this comment NCDWQ voices concern over the magnitude of pollutant loading increases
Please note that Gaston and Mecklenburg Counties which compose 99 percent of the water
quality study area are NPDES Phase II stormwater communities (Section 2 2 2 of the Water
Quality Analysts) As Phase II communities new development greater than or equal to 1 acre is
subject to specific stormwater control standards The Water Quality Analysts does not account for
such stormwater controls in the 2035 No Build and 2035 Preferred Alternative future scenarios
As discussed in Section 3 2 10 of the report site specific information related to future
development which is not available at this time is needed to appropriately model BMPs such as
stormwater controls Consequently the reported results overestimate the runoff and pollutant
loading from areas that would otherwise receive stormwater treatment It is not possible to
determine how much the specific values for each scenario are overestimated but the relative
values between the two scenarios are still valid
2 DWQ provided comments to the North Carolina Turnpike Authority (NCTA) on our review of
the Final Environmental Impact Statement (FEIS) on February 21 2011 One of the
comments is below
Chapter 2 Page 64 of the FEIS states that interviews were conducted with the MPOs
and County Planning Departments to determine whether the updated 2035 forecasts
should serve as the No Build Scenario or the Build Scenario for ICE Study Area
Based on these interviews the Gaston East West Connector was assumed to be
completed in the allocation of future growth to specific zones NCDWQ is unclear
whether this means the road was considered to be completed in the No Build Scenario
Table 2 17 provides the Estimated Change in Impervious Cover by Watershed using
baseline data from 2007 and the 2035 No Build and 2035 Build Scenarios Very little
change in impervious cover is realized between the 2035 No Build and Build
Scenarios The total increase in impervious cover from No Build to Build is 0 5% with
some watersheds showing no increase in impervious cover and some showing a
decrease in impervious cover This information may support the fact that the Gaston
East West Connector was included in the No Build Scenario If the Gaston East West
Connector was included in the No Build Scenario NCDWQ is concerned that this does
not provide an accurate evaluation of the indirect and cumulative impacts associated with
this project If the Gaston East West Connector was included in the models used to
generate data for the No Build Scenario the NCTA will be required to provide modeling
data that does not include the completion of the Gaston East West Connector as part of
the No Build Scenario
To our knowledge this comment has not been addressed It appears based on this
analysis that the land use data input for this model was provided by the Louis Berger
Group Inc DWQ is concerned that if the land use input data was generated using the
amount of impervious cover from Louis Berger Group report the results of the water
quality analysis may be skewed Again DWQ is unclear whether the construction of the
road or portions of the road were included in the 2035 Build Scenario The Water
Quality Analysis states on Page 2 that the No Build Alternative by definition is the
Forecasted land use for the year 2035 without the construction of the project It is also
important to note that in project discussions with other federal agencies DWQ was
advised that the construction of the road was included in the No Build analysis
Therefore based on the potentially conflicting information presented in the FEIS
Water Quality Analysis and verbal discussions with other agencies DWQ will not
consider this analysis complete until we receive written confirmation from each
Metropolitan Planning Organization (MPO) that construction of the road or any
portion of the road (i a construction of the road was allocated for within specific

TAZ units only in the No Budd analysis) was not included in the No Build
analysis
• Responses to all comments received on the Final EIS will be included in the Record of
Decision (ROD)
The Gaston East West Connector was not included in the No Build condition and was not
assumed to be completed in the growth allocations for the No Build scenario The Gaston
East West Connector was included in the Build scenario The impervious surface cover for
the No Build condition shown in Final EIS Table 2 17 does not include the project
For a more detailed version of the information presented in Final EIS Table 2 17 refer to
Table 9 in the Quantitative Indirect and Cumulative Effects Assessment (Quantitative ICE
Assessment) Table 9 shows the direct change in impervious cover in each watershed (e g the
roadway itself) and the indirect change (e g changes due to the difference between No Build
and Build household and employment distribution) that contribute to the total Build Scenario
impervious surface cover One reason the difference in impervious surface maybe less than
NC Division of Water Quality (NCDWQ) expects is that the direct and indirect changes in
impervious surface cover sometimes counteract each other For example the project adds 200
acres of impervious surface directly to the Upper Crowders Creek watershed but the indirect
land use effect reduces impervious surface associated with development by 200 acres
resulting in no net difference between the No Build Scenario and Build Scenario for this
watershed
As discussed in Section 2 4 1 of the Quantitative ICE Assessment interviews were held with
planners from GUAMPO MUMPO RFATS Gaston County Mecklenburg County and York
County Summaries of each meeting are provided in the report All three of the MPOs with
responsibility for developing the demographic forecasts for the study area confirmed that the
Gaston East West Connector was assumed to be completed in the allocation of future growth
to specific zones (Note that this is was not the case for the Monroe Connector /Bypass)
During the demographic forecasting efforts for the Metrolina model additional growth was
added in areas that were expected to become more attractive to development with the project
including southern Gaston County and northern York County This means that the indirect
land use effect of the project is already reflected in the forecasts Therefore the Metrolma
model forecasts were determined to represent the Build condition All the participants
concurred that the forecasts represent the Build condition and it was reasonable to use the
gravity model approach to redistribute households and employment for the No Build
condition Also the Gaston Urban Area s 2035 Long Range Transportation Plan specifically
notes that During the horizon years of 2020 and 2030 the Garden Parkway was instrumental
in luring housing units (Page 7 2 of the LRTP) further supporting the fact that the
socioeconomic forecasts specifically considered the Garden Parkway in allocation of growth
and supporting the use of the Metrolina model socioeconomic forecasts as the Build Scenario
Please note that this is a different situation and a different conclusion regarding the use of the
Metrolina model socioeconomic forecasts than was reached for the Monroe
Connector /Bypass For the Monroe Connector /Bypass the Metrolina model socioeconomic
forecasts were demonstrated to best represent the No Build condition for that project
Although different these conclusions are appropriate for each project based on review of the
data and interviews with local planners for the respective areas
Indirect land use effects are the difference between the No Build and Build condition
allocations of growth The Build condition allocation was already known (the existing MPO
socioeconomic forecasts) To determine the No Build allocation of growth to specific zones
a gravity model analysis was used A key input to the gravity model is zone to zone travel
time information for the No Build and Build conditions For the No Build scenario the
Metrolina travel demand model was run without including the Gaston East West Connector
roadway links For the Build scenario the Metrolina travel demand model was run
incorporating the Gaston East West Connector roadway links The difference in accessibility

MEMORANDUM
To Jennifer Harris P E North Carolina Turnpike Authority
From Polly Lespinasse Division of Water Quality Mooresville Regional Office
Through Brian Wrenn Transportation Permitting Supervisor Division of Water Quality
Subject Comments on the Indirect and Cumulative Effects Water Quantitative Analysis Related to the
Proposed Gaston East West Connector Extending from 1 85 West of the City of Gastonia in
Gaston County to 1 485 near the Charlotte Douglas International Airport in Mecklenburg County
Mecklenburg and Gaston Counties STIP No s U 3321
This office has reviewed the referenced document dated August 2011 The NC Division of Water Quality (NCDWQ) is
responsible for the issuance of the Section 401 Water Quality Certification for activities that impact Waters of the U S
including wetlands It is our understanding that the project as presented will result in impacts to jurisdictional wetlands
streams and other surface waters NCDWQ offers the following comments based on review of the aforementioned
document
Project Specific Comments
The analysis indicates notable increases between the 2035 No Build Analysis and the 2035 Build Analysis
Increases in the amount of total phosphorus (TP) are expected in the Catawba Creek (7 %) Lower Crowders
Creek (5 5 %) Lake Wylie Catawba River (5 3 %) and Beaverdam Creek Catawba River (5 3 %) hydrologic units
(HUs) Increases in total nitrogen (TN) are expected in the Catawba Creek (5 3 %) and Lake Wylie Catawba River
(5 3 %) HUs Additionally increases in annual runoff are expected in the Beaverdam Creek Catawba River
(8 73 %) Catawba Creek (7 97 %) and Lower Crowders Creek (7 28 %) HUs Catawba Creek Lower Crowders
Creek Lake Wylie and Beaverdam Creek are either on North or South Carolinas 2010 303(d) list or have
established TMDLs (total maximum daily loads) Catawba Creek and Lake Wylie are listed for impaired biological
integrity I ower Crowders Creek is listed for impaired biological integrity throughout the reach and fecal coliform
in some stream sections DWQ is very concerned with the potential indirect and cumulative impacts to both
303(d) listed streams and non 303(d) listed streams throughout the study area that may result from the
construction of this road While Beaverdam Creek Catawba River is not currently on the North Carolina 303(d)
list it is expected to see an increase in TP TN and annual runoff Increased pollutants in this HU as a result of
the construction of this project could result in impairment necessitating its listing on the 303(d) list The NCTA is
encouraged to investigate opportunities with local governments to address the indirect and cumulative impacts to
local jurisdictional resources that may be incurred as a result of this project
2 DWQ provided comments to the North Carolina Turnpike Authority (NCTA) on our review of the Final
Environmental Impact Statement (FEIS) on February 21 2011 One of the comments is below
Chapter 2 Page 64 of the FEIS states that interviews were conducted with the MPOs and County Planning
Departments to determine whether the updated 2035 forecasts should serve as the No Build Scenano or the
Mooresville Regional Office
Location 610 East Center Ave Suite 301 Mooresville NC 28115
Phone [phone] Fax [phone] Customer Service 1 877 623 6748
Internet www ncwaterquality org
An Equal Opportunity \ Affirmative Action Employer 501 Recycled/10/ Post Consumer paper
NorthCarohna
Naturally

are necessary
it shall be noted in the document Geotechnical work is approved under
17 If foundation test borings
General 401 Certification Number 3687 /Nationwide Permit No 6 for Survey Act
18 Sediment and erosion control measures ion of North Carolina Sediment and Erosion Control P ann protect water resources m ust be implemented and
sufficient t
maintained in accordance
with the most recent versn
and Design Manual and the most recent version of NCS00052a d work area Approved BMP measures from
s rock
19 All work in or adjacent to stream waters shall be conducted in d to prevent excavation in flowing water
the most current version of NCDOT Construction and Mainteeancep Activities manual such as sandbag
berms cofferdams and other diversion structures shall s used
Coastal Region Evaluation of Wetland Significance
20 While the use of National Wetland Inventory (NWI) map
oil survey maps are useful toots their inherent naccuraaes require that qualified
(NC CREWS) maps ands permit app
personnel perform onsite wetland delineations prior to
merit shall be
should be operated from the bank rather therhaollutantsanto streams I This equipment minimize
s hydraulic
21 Heavy equipment fuels lubricants by
sedimentation and dredmaintained tolpre�e t contam natgion of surface waters from leaking
inspected daily a
fluids or other toxic materials precludes
22 Riprap shall not be placed in the active thalweg
channel or placed in the stramaedl9ned sized randtipstalied
aquatic life passage Bioengineering boulders or structures should be properly
reserved to the maximum extent possible Riparian
23 Riparian vegetation (native trees and shrubs)
shall be p by the end of the growing season
vegetation must be reestabistrucdionithin the construction limits of the project any
following completion of con you have any questions or require
Provide comments on your project Should
NCDWQ appreciates the opportunity top 663 1699
additional info rmation please contact Polly Lespinasse at ( 704 )
cc Liz Hair US Army Corps of Engineers Asheville Field Office
electronic copy)
Chris Militscher Environmental Protection Agency (electronic copy)
Marla Chambers NC Wildlife Resources Servo e (electronic lectronic copy)
Sonia Gregory NCDWQ Central Office (electronic copy)
Sonia Greg y
File Copy

C'A jkan,�
Gaston East -West Connector
Indirect and Cumulative Effects
Water Quality Analysis -Draft
Cleveland, Gaston, and Mecklenburg Counties, North Carolina,
York County, South Carolina
(STIP U -3321)
Prepared for the North Carolina Turnpike Authority
NORTH CAROLINA
f
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Turnpike Authority
-.. -. by
1616 East Millbrook Road Suite 310
Raleigh North Carolina 27609
August 2011 CA
I

Gaston East West Connector Water Quality Analysis
August 2011 - Draft
EXECUTIVE SUMMARY
The North Carolina Turnpike Authority (NCTA) operating as part of the North Carolina Department of
Transportation (NCDOT) proposes the Gaston East West Connector as a controlled access toll road from 1 85
west of the City of Gastonia in Gaston County NC to 1 485 near the Charlotte Douglas International Airport in
Mecklenburg County NC The purpose of the Gaston East West Connector (the Project) is to improve east west
transportation mobility in the area around the Gastonia and other municipalities in southern Gaston County to
the City of Charlotte metropolitan area Importantly the project will establish direct access between the rapidly
growing areas of southeast Gaston County and western Mecklenburg County The Gaston East West Connector
which is locally known as the Garden Parkway is included in the State Transportation Improvement Program
(STIP) as project U 3321
The Gaston East West Connector Draft Environmental Impact Statement (DEIS) circulated in April 2009
included a summary of the qualitative indirect and cumulative effects (ICE) analysis prepared for the Detailed
Study Alternatives (Indirect and Cumulative Effects Assessment for the Gaston East West Connector Louis Berger
Group Inc March 2009) The U S Environmental Protection Agency (EPA) U S Fish and Wildlife Service
(USFWS) N C Department of Environment and Natural Resources (NCDENR) and N C Wildlife Resources
Commission (NCWRC) provided comments on the DEIS Regarding indirect and cumulative effects the
Resource Agencies requested additional quantitative data on the Preferred Alternative
A quantitative indirect and cumulative effects study was prepared for the Preferred Alternative (Gaston East
West Connector Quantitative Indirect and Cumulative Effects Analysis Louis Berger Group Inc August 2010)
This report is summarized in the Projects Final EIS circulated in December 2010 In a comment letter on the
Final EIS dated February 21 2011 the NCDENR Division of Water Quality (NCDWQ) noted that NCDWQ will
require additional modeling of pollutant loadings for this project
This report presents a quantitative water quality analysis performed in response to NCDWQ s requirement and
to determine how estimated induced land use changes resulting from the Project may affect water quality
throughout the 265 square mile Study Area defined for this analysis The water quality analysis involved
constructing watershed models for the nine 12 digit hydrologic units (HUs) comprising the Study Area using the
BasinSim build of the Generalized Watershed Loading Functions (GWLF) model The watershed models were
used to estimate annual runoff and annual overland pollutant loading rates of total nitrogen (TN) total
phosphorus (TP) total suspended sediment (TSS) produced from the three land use scenarios a year 2006
baseline condition (Baseline Condition) year 2035 future condition without the Project (2035 No Build) and
year 2035 future condition with the Project (2035 PA)
Five of the nine HUs composing the Study Area contain streams or waterbodies on the 2010 North Carolina or
South Carolina 303(d) list (NCDWQ 2010a SCDHEC 2010) Catawba Creek Duharts Creek South Fork Catawba
River Lower Crowders Creek Mill Creek Lake Wylie and Upper Crowders Creek The Project alignment
intersects all five HUs Further interchanges are planned in all five HUs The watershed model results for these
five HUs indicate increased runoff and TN and TP loads in the 2035 PA scenario compared to the 2035 No Build
scenario while a decrease in TSS load is predicted for four of the five HUs the exception being the Upper
Crowders Creek HU Of the five HUs the Catawba Creek HU experiences the largest indirect effects the HU
incurs the greatest increase in urban land use and in turn the largest increase in impervious surface coverage
As a result the Catawba Creek HU is projected to have the greatest increases in runoff and nutrient loading
rates
IL

Gaston East West Connector Water Quality Analysis
August 2011 -Draft
10 INTRODUCTION
The North Carolina Turnpike Authority (NCTA) operating as part of the North Carolina Department of
Transportation (NCDOT) proposes the Gaston East West Connector as a controlled access toll road from 1 85
west of the City of Gastonia in Gaston County NC to 1 485 near the Charlotte Douglas International Airport in
Mecklenburg County NC The purpose of the Gaston East West Connector is to improve east west
transportation mobility in the area around the Gastonia and other municipalities in southern Gaston County to
the City of Charlotte metropolitan area Importantly the project will establish direct access between the rapidly
growing areas of southeast Gaston County and western Mecklenburg County The Gaston East West Connector
which is locally known as the Garden Parkway is included in the State Transportation Improvement Program
(STIP) as project U 3321 For the purposes of this report the Gaston East West Connector will be referred to as
the Project
The Gaston East West Connector Draft Environmental Impact Statement (DEIS) circulated in April 2009
included a summary of the qualitative indirect and cumulative effects (ICE) analysis prepared for the Detailed
Study Alternatives (Indirect and Cumulative Effects Assessment for the Gaston East West Connector Louis Berger
Group Inc March 2009) The U S Environmental Protection Agency (EPA) U S Fish and Wildlife Service
(USFWS) N C Department of Environment and Natural Resources (NCDENR) and N C Wildlife Resources
Commission (NCWRC) collectively referred to as the Resource Agencies hereafter provided comments on the
DEIS Regarding indirect and cumulative effects the Resource Agencies requested additional quantitative data
on the Preferred Alternative
A quantitative indirect and cumulative effects study was prepared for the Preferred Alternative (Gaston East
West Connector Quantitative Indirect and Cumulative Effects Analysis Louis Berger Group Inc August 2010)
This report is summarized in the projects Final EIS circulated in December 2010 In a comment letter on the
Final EIS dated February 21 2011 the NCDENR Division of Water Quality (NCDWQ) noted that NCDWQ will
require additional modeling of pollutant loadings for this project
Subsequent to the August 2010 version of the quantitative ICE assessment report circulated with the Final EIS
the quantitative ICE assessment was updated (Gaston East West Connector Quantitative Indirect and Cumulative
Effects Analysis Louis Berger Group Inc July 2011) to include the Fites Creek Catawba River subwatershed
(Hydrologic Unit Code [HUC] 030501011405) fWRA ,b q,"A Q�- ' S L
� r& ��W }) I V_d AA& �
This report presents a quantitative water quality analysis performed in response to NCDWQ' requirement and
to determine how estimated induced land use changes resulting from the Project may affect water quality
throughout the 265 square mile Study Area defined for this analysis The water quality analysis involved
constructing watershed models for the nine 12 digit hydrologic units (HUs) comprising the Study Area The
watershed models were used to estimate annual runoff and annual overland pollutant loading rates of total
nitrogen (TN) total phosphorus (TP) total suspended sediment (TSS) produced from the three land use
scenarios described in Table 1 Comparison of the runoff and pollutant loading rates projected for the 2035 No
Build Alternative (No Build) and 2035 Preferred Alternative (PA) scenarios provides an indication of the Project s
potential water quality effects

Gaston East West Connector Water Quality Analysis
August 2011 -Draft
FIGURES
Figure 1 GWLF surface and sub surface hydrology and loading pathways (adapted from Haith et al 1992) 12
Figure 2 Calibration and Validation Model Monthly Streamflows Plotted with Observed Monthly Streamflow 23
TABLES
Table 1 Land Use Scenarios Considered in the Quantitative Water Quality Analysis
2
Table 2 Study Area Hydrologic Units (HUs)
1
Table 3 Classifications and Use Support Ratings of Named Study Area Waterbodies in North Carolina
2
Table 4 Classifications of Study Area Waterbodies in South Carolina
4
Table 5 Study Area Waterbodies on the North Carolina 2000 — 2010 303(d) Lists
6
Table 6 Study Area Waterbodies on the South Carolina 2000 — 2010 303(d) Lists
7
Table 7 Study Area Stormwater BMPs
10
Table 8 Model Inputs and Data Sources
13
Table 9 NCLD Land Cover Categories for the Study Area
14
Table 10 Quantitative ICE Land Use Class CN Assignments
16
Table 11 LISLE Cover factors
17
Table 12 Study Area Regulated Buffer Widths
19
Table 13 Average Buffer Width by HU
20
Table 14 GWLF Buffer Reduction Efficiencies
20
Table 15 CN and Nitrogen and Phosphorus Buildup Rates for Urban Areas for the Baseline 2035 No Build
(Build) and 2035 PA (PA) Scenarios
25
Table 16 Reported Significant Figures
28
Table 17 Comparison of Annual Runoff Results for Baseline Condition 2035 No Build and 2035 PA Scenarios
29
Table 18 Comparison of Annual Total Nitrogen (TN) Results for Baseline Condition 2035 No Build and 2035
PA
Scenarios
30
Table 19 Comparison of Annual Total Phosphorus (TP) Results for Baseline Condition 2035 No Build and 2035
PA Scenarios
31
Table 20 Comparison of Annual Total Suspended Sediment (TSS) Results for Baseline Condition 2035 No Build
and 2035 PA Scenarios
32
A Large Format Figures
B Select Figures from the Gaston East West Connector Quantitative Indirect and Cumulative Effects
Analysis
C GWLF E and RUNQUAL E Input Parameters
D Correspondence with N C Division of Water Quality Regarding Analysis Methodology
IV

Gaston East West Connector Water Quality Analysis
August 2011 -Draft
TABLE OF CONTENTS
Executive Summary
Table of Contents
Figures
iv
Tables iv
Appendices
iv
10 Introduction
1
20 Study Area
2
2 1 Study Area Definition
2
22 Water Resources
1
2 2 1 Existing Water Quality
5
2 2 2 Existing Water Quality Measures
7
30 Water Quality Analysis Approach
11
3 1 BasinSim Description
11
3 2 Input Parameters
12
32 1 Land Use
14
3 2 2 Soils
15
3 2 3 Curve Numbers
16
3 2 4 Streams
16
3 2 5 Weather Stations
16
3 2 6 Point Sources
17
3 2 7 Surface Elevation
17
3 2 8 Erosion and Sediment Yield
17
3 2 9 Septic Areas
18
3 2 10 Best Management Practice (BMP) Implementation
18
3 3 Model Calibration
21
40 Results and Discussion
23
4 1 Baseline Condition
26
4 2 2035 No Build
27
4 3 2035 Preferred Alternative (PA)
27
4 4 Results Tables
28
5 0 Conclusions
33
6 0 References
35

Gaston East West Connector Water Quality Analysis
August 2011 -Draft
For the Study Area as a whole all nine HUs are anticipated to experience some degree of direct or indirect
effects from the Project Direct effects result from the additional paved surface and right of way associated
with the Project alignment Indirect effects are in the form of increased residential development or
commercial /industrial /office development The result of these effects are apparent in the increases in runoff
and nutrient loading rates projected for all HUs As mentioned above the Catawba Creek HU experiences the
largest indirect effect and is projected to have the largest increase in runoff and nutrient loadings Over 80
percent of the land consumed by the direct and indirect effects of the project is forecasted to come from
existing forest and pasture lands
It should be noted that the analysis documented in this report was not conducted for the purpose of predicting
the specific amount of pollutants delivered at the outlet of each modeled HU Rather the aim of the analysis
was to determine the magnitude of runoff and pollutant change between the 2035 No Build and 2035 PA
scenarios This measurement indicates the trend of water quality over time in each HU and the Study Area as a
whole Also in terms of BMPs the analysis only considered riparian buffers No site specific BMPs —
bioretention basins stormwater ponds grass swales etc — are accounted for in the results Consequently the
watershed model overestimates pollutant loadings from areas that would otherwise receive stormwater
treatment Site specific BMPs were omitted due to a lack information regarding the projected future
development However the three of the four counties intersected by the Study Area — Gaston and Mecklenburg
Counties NC and York County SC — are NPDES Phase II communities Under this designation the counties must
require land disturbances greater than or equal to 1 acre to implement runoff and pollutant reduction measures
(USEPA 2005) Compliance with Phase II rules would likely result in reduced runoff and nutrient loading rates
compared to those produced by the modeled 2035 No Build and 2035 PA scenarios

Gaston East West Connector Water Quality Analysis
August 2011 -Draft
Table 1 Land Use Scenarios Considered in the Quantitative Water Quality Analysis
.. r
Baseline Condition Baseline Land use conditions existing in 2006
2035 No Build Alternative 2035 No Build Forecasted land use for the year 2035 without
construction of the Project
Year 2035 Preferred Alternative 2035 PA Forecasted land use for the year 2035 with
(PA) construction of the PA as presented in the FEIS
The watershed model selected for this analysis was the Virginia Institute of Marine Science BasinSim 10 (VIMS
2000) build of the Generalized Watershed Loading Functions model (Haith and Shoemaker 1987 Haith et al
1992) GWLF is considered an effective tool for watershed planning efforts where runoff and overland pollutant
loadings are primary concerns (EPA 2008) as it simulates runoff and overland nutrient (TN and TP) and sediment
(TSS) loading by considering variable land uses In this analysis land use is isolated as the experimental variable
As such the difference between runoff and loadings calculated by GWLF for the 2035 No Build and 2035 PA
scenarios is dictated by the direct effects of the Project and Project induced development (indirect effects)
captured in the 2035 PA scenario
The water quality analysis scope study area and model selection were coordinated with NCDWQ at a meeting
held on October 18 2010 Minutes from this meeting and follow up emails regarding the Fites Creek Catawba
River subwatershed are included in Appendix C The Fites Creek Catawba River subwatershed was initially
excluded from the quantitative ICE assessment study area used by Louis Berger Group Inc (Berger) due to a lack
of substantial changes in travel times for the majority of this area with the completion of the Gaston East West
Connector However due to the proximity of the southern boundary of the subwatershed to the Preferred
Alternative it was decided that this subwatershed should be included to capture any potential induced growth
that may occur in this subwatershed This water quality analysis also includes the Fites Creek Catawba River
subwatershed
2 0 STUDY AREA
The Study Area marks the extent of the water quality analysis The following sections describe the process by
which the Study Area was defined and the condition of the Study Area water resources
2 1 Study Area Definition
This water quality analysis adopted the Study Area developed for the Gaston East West Connector Quantitative
Indirect and Cumulative Effects (ICE) Analysis performed by (Berger) (Berger 2011) The primary factors
considered in the defining the Study Area included the following the Natural Resources Conservation Service
Watershed Boundary Dataset (NRCS WBD) Subwatershed boundaries (12 digit HUs) potential changes in
accessibility and potential changes in travel times By considering these and other factors in combination
Berger determined the Study Area to be the aggregate extent of the nine 12 digit HUs listed in Table 2
The Study Area is 265 square miles and contains portions of North Carolina and South Carolina From west to
east the Study Area extends from Cleveland County NC through Gaston County NC into western Mecklenburg
County NC From south to north it extends from the Town of Clover SC to the Town of Spence Mountain NC
The North Carolina portion composes 207 square miles (78 percent) of the Study Area while South Carolina
portion constitutes 58 square miles (22 percent) Municipalities located in the Study Area include the Cities of
2

Gaston East West Connector Water Quality Analysis
August 2011 -Draft
Belmont Bessemer City Charlotte Gastionia Kings Mountain Lowell and Mount Holly and Towns of
Cramerton McAdenville Ranlo and Spencer Mountain in North Carolina The Town of Clover is the only
municipality in South Carolina included the Study Area The extent of the Study Area as well as municipalities
and roads are depicted in Figure Al Appendix A
Hydrologic.
Unit Code
030501011404
Table Z Study Area Hydrologic Units (HUs)
Subwatershed Name
Paw Creek Lake Wylie
Quality
umber,
03 08 34
030501011405
Fites Creek Catawba River
03 08 34
030501011406
Lake Wylie Catawba River
03 08 34
030501011501
Upper Crowders Creek
03 08 37
030501011502
Catawba Creek
03 08 37
030501011503
Beaverdam Creek Catawba River
Located in South Carolina
030501011504
Lower Crowders Creek
03 08 37
030501011505
Mill Creek Lake Wylie
03 08 34 03 08 37
030501020605
Duharts Creek South Fork Catawba River
03 08 36
2 2 Water Resources
The Study Area is located on the border of North and South Carolina within the Catawba Santee River Basin
The entirety of the Study Area is located within the Catawba River Basin (0305) and includes portions the
Catawba River Headwaters Subbasin (USGS Hydrologic Unit [HUC] 03050101) and the South Fork Catawba River
Subbasin (USGS HUC 03050102) (NCDWQ 2010b) The Study Area includes the nine 12 digit HUs listed in Table
2 Streams in the North Carolina portion of the Study Area represent 76 percent of the total stream footage
South Carolina contains 24 percent of the Study Area stream footage
The Study Area contains 36 named streams (Table 3) from both North and South Carolina The headwaters of 26
streams occur within the Study Area Abernathy Creek Anthony Creek Beaverdam Creek Blackwood Creek
Camp Run Catawba Creek Crowders Creek Duharts Creek Ferguson Branch First Creek Fites Creek Little Paw
Creek McGill Creek Mill Creek Neal Branch Oates Creek Paw Creek Porter Branch Rocky Branch Shoal
Branch South Crowders Creek Spring Creek Squirrel Branch Stowe Branch Studman Branch and Ticer Branch
Classifications are assigned to waters of the State of North Carolina based on the existing or contemplated best
usage Thirty of the named streams within the Catawba Study Area are Class C streams Class C streams are
protected for secondary recreation fishing wildlife fish and aquatic life propagation and other uses (NCDWQ
2009) The Study Area also includes three WS IV (Water Supply IV) streams and three WS V (Water Supply V)
streams Water Supply III and IV streams are used as sources of water supply for drinking culinary or food
processing purposes and are protected through restrictions on development and waste water discharges Water
Supply V streams are also used as sources of water supply but have no categorical restrictions on watershed
development or wastewater discharges Local governments are not required to adopt watershed protection
ordinances for Water Supply V streams but are required to do so for WS III and WS IV streams (NCDWQ 2009)
Of the streams with Water Supply classifications four are also assigned a CA (Critical Area) designation CA
refers to an area adjacent to the water supply intake where risk associated with pollution is greater than from
the remaining portions of the watershed (NCDWQ 2007a) CAs require additional restrictions on watershed
development beyond those required for a WS classification Table 3 lists the best usage classifications for all
named streams within the North Carolina portion of the Study Area
1

Gaston East West Connector Water Quality Analysis
August 2011 -Draft
The North Carolina Division of Water Quality (NCDWQ) has Initiated a whole basin approach to water quality
management for the 17 river basins within the state Water quality for the Study Area is summarized in the
Catawba River Basinwide Water Quality Plan (NCDWQ 2010b) Water quality within the Catawba River Basin is
assessed by sampling of fish and benthic macroinvertebrates and data collected at ambient (chemical and
physical water quality) monitoring stations The collected data Is compared against water quality standards in
order to evaluate the various best uses of North Carolina waters Including aquatic life or biological integrity
recreation or swimming and water supply Table 3 lists the use support categories for aquatic life recreation
and water supply use for all NCDWQ evaluated waterbodies within the Study Area Blank cells indicate use
support category was not rated
Similarly the South Carolina Department of Health and Environmental Control (SCDHEC) assigns use
classifications to waters of the state The classifications establish the general rules and specific water quality
criteria applicable to a given waterbody for protecting Its classification and existing use All Study Area streams
in South Carolina carry the Freshwaters (FW) classification Freshwaters are suitable for primary and secondary
contact recreation as a source of drinking water supply after conventional treatment for fishing and the
survival and propagation of aquatic fauna and flora and for industrial and agricultural uses (SCDHEC 2006a
2008a)
Table 4 presents the named waterbodles of the Study Area located in South Carolina Stream classifications are
Included but use support ratings are not
T�kio 2 rinccifientinne nnrl [Ica Ciinnnrf Ratinoc of Named Study Area Waterbodles In North Carolina
Classification w
Wat6riteGly v Description Classification AN 0
juat
El
11 135 4a Abernethy Creek From source to First C Supporting
Creek
11 135 4b
Abernethy Creek
From First Creek to
C
Supporting
Crowders Creek
11 130 2 (1)
Anthony Creek
From source to Dam at
C
(Robinwood Lake)
Robinwood Lake
11 130 2 (2)
Anthony Creek
From Dam at
C
Robinwood lake to
Catawba Creek
11 126
Beaverdam Creek
From source to Lake
C
Wylie Catawba River
11 135 5
Bessemer Branch
From source to
C
Crowders Creek
11 135 7
Blackwood Creek
From source to
C
Supporting
Supporting
Crowders Creek
11 130a
Catawba Creek
From source to
C
Supporting
Supporting
SR2446 Gaston
11 130b
Catawba Creek
From SR2446 Gaston
C
Supporting
Supporting
to SR2439 Gaston
11 130c
Catawba Creek
FromSR2439 to Lake
C
Supporting
Wylie
11 (117)
CATAWBA RIVER
From Mountain Island
WS IV CA
Supporting
Supporting
Supporting
(Lake Wylie below
Dam to Interstate
elevation 570)
Highway 85 Bridge at
Belmont
11 (122)
CATAWBA RIVER
From 185 bridge to
WS IV B CA
Supporting
Supporting
Supporting
(Lake Wylie below
the upstream side of
elevation 570)
Paw Creek Arm of
Lake Wylie Catawba
River
N

Gaston East West Connector Water Quality Analysis
August 2011 -Draft
Classification
Index
Waterbody
Description
Classification
Use Support Ratirij,
Mquatild
11 MWater
Sup
11 (123 5)
CATAWBA RIVER
From the upstream
WS V B
Supporting
Supporting
Supporting
(Lake Wylie below
side of Paw Creek Arm
elevation 570)
of Lake Wylie to North
North Carolina
Carolina South
portion
Carolina State Line
11 135a
Crowders Creek
From source to
C
Supporting
SR1118
11 135b
Crowders Creek
From State Route
C
Supporting
1118 to State Route
1122
11 135c
Crowders Creek
From State Route
C
Supporting
1122 to State Route
1131
11 135d
Crowders Creek
From State Route
C
Supporting
1131 to State Route
1108
it 135e
Crowders Creek
From State Route
C
Supporting
Supporting
1108 To NC 321
11 135f
Crowders Creek
From State Route 321
C
Supporting
Supporting
to State Route 2424
11 1358
Crowders Creek
From State Route
C
Supporting
Supporting
2424 to North
Carolina South
Carolina State Line
11 129 19
Duharts Creek
From source to South
WS V
Supporting
Supporting
Supporting
Fork Catawba River
11 1358
Ferguson Branch
From source to
C
Crowders Creek
11 1354 1
First Creek
From source to
C
Abernethy Creek
it 121 (1)
Fites Creek
From source to a point
WS IV
Supporting
Supporting
Supporting
0 3 mile downstream
of N C Hwy 273
11 121 (2)
Fites Creek
From source to a point
WS IV CA
0 3 mile downstream
of N C Hwy 273 to
Lake Wylie Catawba
River
11 129 17
Housers Branch
From source to South
C
Fork Catawba River
11 126 1
Legion Lake and
Entire lake and
C
Shoaf Lake
connecting stream to
Beaverdam Creek
11 125
Little Paw Creek
From source to Lake
C
(Danga Lake)
Wylie Catawba River
11 132
Long Cove
From source to Lake
C
Wylie Catawba River
11 135 9
McGill Branch
From source to
C
Supporting
Supporting
Crowders Creek
11 135 2
McGill Creek
From source to
C
Supporting
Crowders Creek
11 131
Mill Creek
From source to North
C
Carolina South
Carolina State Line

Gaston East West Connector Water Quality Analysis
August 2011 -Draft
Classification
of Study Area Waterbodies in Soutn
Description
The entire stream tributary to Crowders Creek
caroilna
FW
Brown Creek
The entire stream tributary
Index
Camp Run
The entire stream tributary to Beaverdam Creek
FW
C
y1
Wl' MPUPRItey
The enitre stream tributary to Lake Wylie
FW
Lake Wylie
The entire lake on Catawba River
f
11 128
Neal Branch
From source to Lake
C
The entire stream tributary to Crowders Creek
FW
(Armour Creek)
Wylie Catawba River
11 135 6
Oakland Lake
Entire lake and
C
connecting stream to
Crowders Creek
11 135 5 1
Oates Creek
From source to
C
Bessemer Branch
it 124
Paw Creek
From source to Lake
C
Wylie Catawba River
11 133
Porter Branch
From source to Lake
C
Wylie Catawba River
11 135 11
Rocky Branch
From source to North
C
Carolina South
Carolina State Line
11 1304
Shoal Branch
From source to
C
Catawba Creek
11 135 10 1
South Crowders
From source to South
C
Impaired
Supporting
Creek
Fork Crowders Creek
11 129 (15 5)
South Fork
From a point 0 4 mile
WS V
Impaired
Supporting
Supporting
Catawba River
upstream of Long
Creek to Cramerton
Dam and Lake Wylie at
Upper Armstrong
Bridge (mouth of
South Fork Catawba
River)
11 135 10
South Fork
North Carolina Portion
C
Supporting
Crowders Creek
11 135 1
Squirrel Branch
From source to
C
Crowders Creek
11 127
Stowe Branch
From source to Lake
C
Wylie Catawba River
11 134
Studman Branch
From source to Lake
C
Wylie Catawba River
11 124 1
Ticer Branch (Tiser
From source to Paw
C
Branch)
Creek
B Primary Recreation Fresh Water
C Aquatic Life Secondary Recreation Fres
CA Critical Area
WS IV Water Supply IV Highly Developed
WS V Water Supply V Upstream
Table 4 Classltications
Water6ody
Beaverdam Creek
of Study Area Waterbodies in Soutn
Description
The entire stream tributary to Crowders Creek
caroilna
FW
Brown Creek
The entire stream tributary
FW
Camp Run
The entire stream tributary to Beaverdam Creek
FW
Crowders Creek
The enitre stream tributary to Lake Wylie
FW
Lake Wylie
The entire lake on Catawba River
FW
Mill Creek
The emtre stream tributary to Lake Wylie
FW
Rocky Branch
The entire stream tributary to Crowders Creek
FW

Gaston East West Connector Water Quality Analysis
August 2011 -Draft
2 2 1 Existing Water Quality
NCDWQ and SCDHEC are required by Clean Water Act Section 303(d) and 40 CFR 130 7 to maintain a list of
impaired waterbodies Commonly referred to as the 303(d) list the list is typically corr3plied every two years
with the last effective final list dated 2010 for North Carolina and South Carolina These lists are a
comprehensive accounting of all impaired waterbodies An impaired waterbody is one that does not meet
water quality standards including designated uses numeric and narrative criteria and anti degradation
requirements defined in 40 CFR 131 The standard violations may be due to an individual pollutant multiple
pollutants or an unknown cause of impairment The impairment could come from point sources non point
sources and /or atmospheric deposition
In both states inclusion to the 303(d) list is based upon use support guidelines in Section 305(b) (USEPA 841 B
97 002A and 002B) Those waterbodies only attaining Partially Supporting or Not Supporting status are
included on the 303(d) list Tables 5 and 6 list the Study Area waterbodies that are found on the year 2000 to
2010 303(d) lists for North and South Carolina The waterbodies occur in the Catawba Creek Duharts Creek —
South Fork Catawba River Lower Crowders Creek Mill Creek Lake Wylie and Upper Crowder Creek HUs (Figure
A2 Appendix A)
Review of current and past 303(d) lists as well as the NCDWQ Catawba River Basinwide Water Quality Plan and
SCDHEC Catawba River Basin Watershed Water Quality Assessment provide an indication of water quality trends
in the Study Area Based on inspection of Tables 5 and 6 it is apparent the number of Study Area waterbodies
listed as impaired by North Carolina has increased slightly over the period from 2000 (12 listed waterbodies) to
2010 (14 listed waterbodies) (NCDWQ 2000 2003 2006 2007b 2010a 2010c) In contrast South Carolina has
seen a marked reduction in the number of impaired waterbodies from six in 2000 to two in 2010 (SCDHEC 2000
2002 2004 2006b 2008b 2010) In all cases the waterbodies delisted by South Carolina between 2008 and
2010 were removed because water quality standards were attained (SCDHEC 2010)
Additionally Clean Water Act Section 303(d) requires states to develop Total Maximum Daily Loads (TMDLs) for
impaired waterbodies A TMDL establishes 1) the maximum amount of a pollutant a waterbody can receive and
still comply with water quality standards and 2) pollutant loading limits on known sources By accounting for
and limiting loadings of a pollutant steps can then be taken to restore the waterbody to its assigned uses
(USEPA 1991 from Crowders Creek TMDL) The following waterbodies in the Study Area have existing TMDLs
Crowders Creek Lake Wylie Beaverdam Creek and Brown Creek
In 2004 NCDWQ in coordination with SCDHEC developed a TMDL for fecal coliform bacteria (FCB) for the last
four miles of Crowders Creek from State Route 1108 to the North Carolina /South Carolina state line
(classification indexes 11 135e g) This section of Crowders Creek in North Carolina as well as the remainder in
South Carolina has historically experienced elevated FCB concentrations as indicated by its listing on the North
and South Carolina 303(d) lists for over a decade and the implementation of a previous TMDL in 1996 Sources
of FCB are attributed to discharge from multiple waste water treatment plants faulty sewage collection system
lines septic systems biosolids application and livestock
Lake Wylie has a history of nutrient enrichment problems In 1992 a report authored by the NCDWQ and
SCDHEC concluded the lake s assimilative capacity for nutrients was exhausted Subsequently the Lake Wylie
Nutrient Management Plan and accompanying TMDL was implemented in 1996 The nutrient management
5

Gaston East West Connector Water Quality Analysis
August 2011 - Draft
strategy established by the TMDL targeted non point source reductions and placed stringent nutrient removal
requirements on point source dischargers to the most highly eutrophic arms of the lake (NCDWQ 2010b) The
latest water quality data reported in the 2010 Catawba River Basinwide Water Quality Plan (NC DWQ 2010b)
indicates nutrient enrichment remains a problem in the lake Samples of the main stem of Lake Wylie produced
no chlorophyll a standard exceedances yet all samples demonstrated elevated chlorophyll a Further sampling
from the Crowders Creek and South Fork Catawba arms of the lake suggested localized areas of eutrophication
In addition to nutrient enrichment portions of Lake Wylie have more recently been cited as impaired for aquatic
life support due to water quality standard exceedances of low pH copper chlorophyll a and high water
temperature
SCDHEC developed FCB TMDLs for two streams in the Study Area — Beaverdam Creek and Brown Creek — in
2001 For Beaverdam Creek runoff from livestock pastures and built up land were noted as the primary and
secondary FCB sources (SCDHEC 2001a) In the case of Brown Creek urban runoff as well as failing septic
systems and direct sewage discharges were described as the principal sources of FCB (SCDHEC 2001b)
Rl
Table 5 Study
Area Waterbodies
on the North Carolina 2000
— 2010
303(d)
Lists
00
00 2
2004
2006
00
t i
list
list
list
list
list
list
11 135 4b
Abernethy Creek
From First Creek to
Impaired biological integrity
No
No
No
Yes
Yes
No
Crowders Creek
11 130a
Catawba Creek
From source toSR2446
Unknown (2000 02) impaired
Yes
Yes
Yes
Yes
Yes
Yes
Gaston
biological integrity (2004 10)
11 130b
Catawba Creek
From SR2446 Gaston to
Unknown (2000 02) impaired
Yes
Yes
Yes
Yes
Yes
Yes
SR2439 Gaston
biological integrity (2004 10)
11 130c
Catawba Creek
FromSR2439 to Lake
Unknown (2000 02) impaired
Yes
Yes
Yes
Yes
Yes
Yes
Wylie
biological integrity (2004 10)
11 (117)
Catawba River (Lake
From 1 85 bridge to the
Low pH
No
No
No
No
Yes
Yes
Wylie below elevation
upstream side of Paw
570)
Creek Arm of Lake Wylie
Catawba River
11 (123 5)b
Catawba River (Lake
South Fork Catawba
Copper chlorophyll a (2008)
No
No
No
No
Yes
Yes
Wylie South Fork
River Arm of Lake Wylie
turbidity (2008) high water
Catawba arm) North
temperature (2010)
Carolina portion
11 135a
Crowders Creek
From source to SR 1118
Unknown (2000 02) impaired
Yes
Yes
Yes
Yes
Yes
Yes
biological integrity (2004 10)
11 135b
Crowders Creek
From State Route 1118
U k ow (2000 02) mpaired
Yes
Yes
Yes
No
Yes
No
to State Route 1122
biological integrity (2004 2008)
11 135c
Crowders Creek
From State Route 1122
Unknown (2000 02) impaired
Yes
Yes
Yes
Yes
Yes
Yes
to State Route 1131
biological integrity (2004 10)
11 13Sd
Crowders Creek
From State Route 1131
Unknown (2000 02) impaired
Yes
Yes
Yes
Yes
Yes
Yes
to State Route 1108
biological integrity (2004 10)
11 135e
Crowders Creek
From State Route 1108
Fecal Coliform impaired biological
Yes
Yes
Yes
Yes
Yes
Yes
To NC 321
integrity (2004 06 2010)
11 135f
Crowders Creek
From State Route 321 to
Fecal Coliform impaired biological
Yes
Yes
Yes
Yes
Yes
Yes
State Route 2424
integrity (2004 06 2010)
11 135g
Crowders Creek
From State Route 2424
Fecal Coliform (2000 06 impaired
Yes
Yes
Yes
Yes
Yes
No
to NC /SC Line
biological integrity (2006 08)
11 135 2
McGill Creek
From source to
Unknown (2000 02) impaired
Yes
Yes
Yes
Yes
Yes
Yes
Crowders Creek
biological integrity (2004 10)
11 135 10 1
South Crowders Creek
From source to South
Low Dissolved Oxygen
No
No
No
No
No
Yes
Fork Crowders Creek
11 129 (15S)
South Fork Catawba
From a point 0 4 mile
Turbidity low pH (2010)
No
No
No
No
Yes
Yes
River
upstream of Long Creek
Rl

Gaston East West Connector Water Quality Analysis
August 2011 -Draft
2 2 2 Existing Water Quality Measures
As part of the preparation for the modeling effort and in order to determine whether existing regulations and
ordinances are sufficient to protect water quality Atkins inventoried the variety of protective measures for
riparian buffer widths and stormwater requirements of the different planning jurisdictions within the Study
Area Government organizations that were considered include the North Carolina municipalities of Belmont
Bessemer City Charlotte Cramerton Gastionia Kings Mountain Lowell McAdenville Mount Holly Ranlo and
Spencer Mountain in South Carolina and the Town of Clover was considered
Additionally EPA Phase I or Phase II Stormwater Rules are in effect in nearly the entire Study Area (99 percent)
NCDWQ Identifies the City of Charlotte as a Phase I stormwater permlttee by the EPA as of 1993 As required
by National Pollutant Discharge Elimination System ( NPDES) regulations Charlotte must develop and Implement
a storm water program Including public education Illicit discharge detection and elimination storm sewer
system and land use mapping and analytical monitoring Gaston County NC and York County SC are both
Phase II stormwater permlttees NPDES regulations require them to at a minimum develop Implement and
enforce a storm water program designed to reduce the discharge of pollutants from the municipal separate
storm sewer system (MS4) Stormwater best management practices (BMPs) drafted by Gaston and
Mecklenburg Counties are provided In Table 7
7
Table 6 Study
Area Waterbodies on the South Carolina 2000
— 2010
303(d)
Lists
•
000
2002
2004 00
00
Station
...
Watery
Description Stressor
list
list
list list
list
list
CW 023
Crowders Creek
Crowders Creek at S 46 Fecal coliform (2000 04) cadmium
Yes
Yes Yes
Yes
No
564 NE Clover (2006) copper (2006 08)
CW 024
Crowders Creek
Crowders Creek at S 46 Impaired biological integrity fecal
Yes
FYe
Yes
Yes
Yes
No
1104 coliform (2000 2004)
CW 027
Lake Wylie
Lake Wylie Crowders Fecal coliform (2000 04 2008 10)
Yes
Yes
Yes
Yes
Yes
Creek arm at SC 49 and copper (2006)
CW 105
Brown Creek
Brown Creek at S 46 228 Fecal coliform (2000) Turbidity
Yes
No
Yes
Yes
Yes
No
(Guinn St) 0 3 mile west
CW 152
Crowders Creek
Crowders Creek at US
Copper fecal coliform
No
Yes
No
No
No
No
3210 5 mile north OF NC
state line
CW 153
Beaverdam Creek
Beaverdam Creek at S
Fecal coliform (2000) turbidity
Yes
No
No
Yes
Yes
No
46 152 8 miles east of
(2006 08)
CW 192
South Fork Crowders
South Fork Crowders
Fecal colilform
Yes
Yes
Yes
No
No
No
Creek
Creek at S 46 79 4 5
CW 197
Lake Wylie
Lake Wylie at Mill Creek
Copper
No
No
Yes
Yes
Yes
No
arm at end of S 46 557
RS 06020
Beaverdam Creek
Beaverdam Creek at
Impaired biological integrity
No
No
No
No
Yes
Yes
bridge on S 46 64 3 2
2 2 2 Existing Water Quality Measures
As part of the preparation for the modeling effort and in order to determine whether existing regulations and
ordinances are sufficient to protect water quality Atkins inventoried the variety of protective measures for
riparian buffer widths and stormwater requirements of the different planning jurisdictions within the Study
Area Government organizations that were considered include the North Carolina municipalities of Belmont
Bessemer City Charlotte Cramerton Gastionia Kings Mountain Lowell McAdenville Mount Holly Ranlo and
Spencer Mountain in South Carolina and the Town of Clover was considered
Additionally EPA Phase I or Phase II Stormwater Rules are in effect in nearly the entire Study Area (99 percent)
NCDWQ Identifies the City of Charlotte as a Phase I stormwater permlttee by the EPA as of 1993 As required
by National Pollutant Discharge Elimination System ( NPDES) regulations Charlotte must develop and Implement
a storm water program Including public education Illicit discharge detection and elimination storm sewer
system and land use mapping and analytical monitoring Gaston County NC and York County SC are both
Phase II stormwater permlttees NPDES regulations require them to at a minimum develop Implement and
enforce a storm water program designed to reduce the discharge of pollutants from the municipal separate
storm sewer system (MS4) Stormwater best management practices (BMPs) drafted by Gaston and
Mecklenburg Counties are provided In Table 7
7

Gaston East West Connector Water Quality Analysis
August 2011 - Draft
3 0 WATER QUALITY ANALYSIS APPROACH
This section outlines the methodology used to quantify the Projects potential water quality effects The
BasinSim GWLF watershed model employed in the analysis is discussed in detail The procedures used to derive
model input parameters special model considerations and model calibration are also presented
3 1 BasinSim Description
BasinSim is a desktop simulation system that predicts sediment and nutrient loads for small to mid sized
watersheds The simulation system is based on the Generalized Watershed Loading Functions (GWLF) a tested
watershed model developed by Dr Douglas Haith and his colleagues at Cornell University New York (Haith and
Shoemaker 1987 Haith et al 1992) BasinSim 10 integrates an easy to use graphic Windows interface
extensive databases (land uses population soils water discharge water quality climate point nutrient sources
etc ) and the GWLF model (with modifications) into a single software package It was designed to enable
resource managers to visualize watershed characteristics retrieve historic data (at the county and sub
watershed levels) manipulate land use patterns and simulate nutrient (N P and organic C) and sediment
loadings under various scenarios The latest version of BasinSim version 10 0 was released in April 1999
The GWLF model developed by Haith and Shoemaker (1987) is currently used in different platforms under
different names (Dai et al 2000 Schneiderman et al 2002 Evans et al 2002 Hong and Swaney 2004 Morth et
al 2007) Each version has particular modifications but all follow the same conceptual framework GWLF
simulates runoff sediment delivery and average nutrient concentration based on land use Figure 1 depicts the
mayor components of GWLF The model uses daily steps for weather data and water balance calculation
Evapotranspiration is determined using daily weather data and a cover factor dependent upon land use /land
cover type Sediment and nutrient loads are estimated monthly based on the daily water balance accumulated
to monthly values
GWLF has been described as an engineering compromise between the empiricism of export coefficients and
the complexity of chemical simulation models (Haith and Shoemaker 1987) GWLF is considered a combined
distributed /lumped parameter watershed model For surface loading it is distributed in the sense that it allows
multiple land use /land cover scenarios but each area is assumed to be homogenous with regard to various
attributes considered by the model The model does not spatially distribute the source areas but simply
aggregates the loads from each area into a watershed total in other words there is no spatial routing
Groundwater runoff and discharge are obtained from a lumped parameter watershed water balance for both
shallow saturated and unsaturated zones
Runoff is calculated by means of the US Soil Conservation Services (SCS) curve number equation (SCS 1986)
The Universal Soil Loss Equation (USLE) is applied to simulate erosion Rural nutrients are estimated using
empirical concentrations of each land use which are based on both dissolved concentration in runoff and solid
concentration in sediment Urban nutrient loads are computed by exponential accumulation and washoff
functions Nutrient loads from septic systems are calculated by estimating the per capita daily load from each
type of septic system and the number of people in the watershed served by each type Sub surface losses are
calculated using dissolved N and P coefficients for shallow groundwater contributions to stream nutrient loads
and the sub surface sub model only considers a single lumped parameter contributing area as mentioned
previously GWLF does not include instream flow and transport of loads However GWLF provides for ground
water discharges to stream systems offering an opportunity for calibrating instream flow volume
11

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Gaston East West Connector Water Quality Analysis
August 2011 - Draft
Figure 1 GWLF surface and sub surface hydrology and loading pathways (adapted from Haith et al 1992)
BasinSim s implementation of GWLF has incorporated a variable seepage control into the model replacing a
constant seepage coefficient to help with calibration of streamflow GWLF in BasinSim also supplies a time
delay feature which postpones the effect of weather events on stream responses a population growth function
which permits the nutrient contribution by septic systems to change over time and the ability to assign variable
nutrient concentrations as a function of streamflow
3 2 Input Parameters
Spatial (GIS data layers) and non spatial data were used to derive input parameters for the GWLF watershed
model Data sources are listed in Table 8 and their use is described in the following sections Table 8 also lists
the units significant figures and decimal places used for the model inputs Significant figures are not relevant
to some of the data listed such as the aerial photography and sewer service extent data With the exception of
the Study Area land use the significant figures and decimal places listed are determined by the data provider
I
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Gaston East West Connector Water Quality Analysis
August2011 - Draft
3 2 1 Land Use
Study Area land use for the Baseline Condition 2035 No Build and 2035 PA scenarios was provided by Berger
and described in the Gaston East West Connector Quantitative Indirect and Cumulative Effects Analysis (Berger
2011) The land use datasets were developed as part of the Gaston East West Connector quantitative ICE
analysis
A spatially explicit Baseline Condition land use dataset was produced for the year 2006 condition of the Study
Area by using high resolution aerial photography to update the 2001 National Land Cover Database (NLCD)
(USGS 2003) The NLCD is a spatially explicit gridded dataset with a 30 meter resolution That is each 30
meter by 30 meter grid cell in the dataset is assigned a land cover category The update process focused on
identifying large areas of land such as subdivisions and shopping centers that converted from forest to
developed land cover in the interim time period The land cover categories of the NLCD grid cells were modified
to reflect areas of land use conversion Fifteen NLCD 2001 land cover categories occur in the Study Area (see
Table 9)
Land use forecasts for the 2035 No Build and 2035 PA scenarios in contrast were developed as non spatially
explicit datasets In other words the individual 30 meter by 30 meter grid cells of the spatially explicit Baseline
Condition land use dataset were not changed to reflect a land use conversion in the future scenarios Instead
the land use forecasts were performed at the scale of Traffic Analysis Zones (TAZs) The Study Area was found
to encompass 275 TAZs The TAZ boundaries however did not necessarily conform to the HU boundaries of the
Study Area To summarize the TAZ land use forecasts by HU the 275 TAZs were intersected with the nine Study
Area HUs The result was 387 forecasting zones with each zone corresponding to exactly one TAZ and one HU
The forecasting zones provided the geographic framework for the 2035 No Build and 2035 PA land use forecasts
and are the smallest unit for which land use change results are reported
Figures depicting the forecasting zones and results of the quantitative ICE analysis are provided in Appendix B
Further explanation of the land use forecast can be found in the Gaston East West Connector Quantitative
Indirect and Cumulative Effects Analysis (Berger 2011)
Table 9 NCLD
Land Cover Categories for the Study Area
r
-'Diescriotiphi-
All areas of open water generally with less than 25/ cover of
vegetation or soil
Open Water
Includes areas with a mixture of some constructed materials but
mostly vegetation in the form of lawn grasses Impervious surfaces
account for less than 20% of total cover These areas most
Developed Open Space
commonly include large lot single family housing units parks golf
courses and vegetation planted in developed settings for
recreation erosion control or aesthetic purposes
Includes areas with a mixture of constructed materials and
vegetation Impervious surfaces account for 20 49/ of total cover
Developed Low Intensity
These areas most commonly include single family housing units
Includes areas with a mixture of constructed materials and
vegetation Impervious surfaces account for 50 79% of the total
Developed Medium Intensity
cover These areas most commonly include single family housing
units
14

Gaston East West Connector Water Quality Analysis
August2011 -Draft
N,LCD, Cate
Includes highly developed areas where people reside or work in
Developed High Intensity
high numbers Examples include apartment complexes row houses
and commercial /industrial Impervious surfaces account for 80
100/ of the total cover
Barren areas of bedrock desert pavement scarps talus slides
Barren Land (Rock /Sand /Clay)
volcanic material glacial debris sand dunes strip mines gravel pits
and other accumulations of earthen material Generally vegetation
accounts for less than 15/ of total cover
Areas dominated by trees generally greater than 5 meters tall and
Deciduous Forest
greater than 20/ of total vegetation cover More than 75/ of the
tree species shed foliage simultaneously in response to seasonal
change
Areas dominated by trees generally greater than 5 meters tall and
greater than 20% of total vegetation cover More than 75% of the
Evergreen Forest
tree species maintain their leaves all year Canopy is never without
green foliage
Areas dominated by trees generally greater than 5 meters tall and
Mixed Forest
greater than 20/ of total vegetation cover Neither deciduous nor
evergreen species are greater than 75/0 of total tree cover
Areas dominated by shrubs less than 5 meters tall with shrub
Shrub /Scrub
canopy typically greater than 20/ of total vegetation This class
includes true shrubs young trees in an early successional stage or
trees stunted from environmental conditions
Areas dominated by grammanoid or herbaceous vegetation
Grassland /Herbaceous
generally greater than 80% of total vegetation These areas are not
subject to intensive management such as tilling but can be utilized
for grazing
Areas of grasses legumes or grass legume mixtures planted for
Pasture /Hay
livestock grazing or the production of seed or hay crops typically on
a perennial cycle Pasture /hay vegetation accounts for greater than
209/ of total vegetation
Areas used for the production of annual crops such as corn
soybeans vegetables tobacco and cotton and also perennial
Cultivated Crops
woody crops such as orchards and vineyards Crop vegetation
accounts for greater than 209/ of total vegetation This class also
includes all land being actively tilled
Areas where forest or shrubland vegetation accounts for greater
Woody Wetlands
than 20/ of vegetative cover and the soil or substrate is
periodically saturated with or covered with water
Areas where perennial herbaceous vegetation accounts for greater
than 80% of vegetative cover and the soil or substrate is
Emergent Herbaceous Wetlands
periodically saturated with or covered with water
3 2 2 Soils
Spatial and tabular Soil Survey Geographic (SSURGO) soil information was downloaded from NRCS (NRCS 2010)
for Cleveland Gaston and Mecklenburg Counties NC as well as York County SC The soils were clipped to the
15

Gaston East West Connector Water Quality Analysis
August 2011 -Draft
3 2 6 Point Sources
Location of point source dischargers within the Study Area were identified by retrieving NPDES permits from
NCDWQ (NCDWQ 2011a) and SCDHEC (Larry Turner SCDHEC personal communication 6/20/2011) Monthly
discharge reports for all dischargers were retrieved from NCDWQ for 2009 (NCDWQ 2011b) Additionally
monthly discharge permits for dischargers in the calibration watersheds were retrieved for the calibration and
validation periods 1999 2003 (Jaeha Ho SCDHEC personal communication 10/7/2010)
3 2 7 Surface Elevation
A 20 foot resolution Digital Elevation Model (DEM) was constructed for the Study Area Elevation data for the
North Carolina portion of the Study Area were obtained from N C Floodplain Mapping Program (NCFMP)
(NCFMP 2007) Elevation data for the portion of the Study Area extending to South Carolina was obtained from
the U S Geologic Survey National Elevation Dataset (USGS 2009)
3 2 8 Erosion and Sediment Yield
GWLF computes erosion using the Universal Soil Loss Equation (USLE) and the sediment yield is the product of
erosion and sediment delivery ratio Models derived from USLE are some of the most widely applied tools for
predicting sediment yield from catchments USLE factors K LS C and P must be specified as the product K * LS *
C * P for each rural runoff source area Erosion from urban land is not explicitly handled by GWLF For sediment
loading from urban land uses some applications of GWLF (e g Schneiderman et al 2002) use the accumulation
and washoff functions given for nutrients in the original model (Haith et al 1992) substituting sediment
accumulation rates given in Haith et al (1992) for particulate nutrient accumulation rates In this application of
GWLF USLE was used to compute erosion from urban areas as well
Residential and rural residential land uses are not addressed directly by USLE though a number of studies have
successfully applied USLE to catchments containing an urban component (Ricker et al 2008 Jackson et al
2005 Fu et al 2005 and Boyle et al 2011) Estimates of the percent tree cover bare soil grass and relative
herbaceous cover based on Study Area observations and land use descriptions were used to estimate the
appropriate C factors for urban land covers in this study (Table 11) in a manner similar to the method used to
calculate C factors for rural land uses USLE K LS and P factors for urban land use were estimated in the same
manner as for rural land uses (Appendix B)
Table 11 USLE Cover factors
Open Water
0
Developed High Intensity
0
Woody Wetlands
0 003
Emergent Herbaceous Wetlands
0 004
Evergreen Forest
0 004
Grassland /Herbaceous
0 004
Shrub /Scrub
0 004
Mixed Forest
0 007
Deciduous Forest
0 009
Developed Medium Intensity
002
Developed Low Intensity
003
Developed Open Space
004
Pasture /Hay
005
Cultivated Crops
024
Barren Land (Rock /Sand /Clay)
1
17

Gaston East West Connector Water Quality Analysis
August 2011 -Draft
Study Area boundary Soil series or map units which occurred in the Study Area were assigned available
water holding capacity soil erodibility (K) factor dominant hydrologic soil group and organic matter content as
required by GWLF Available water holding capacity was assigned by using the Available Water Storage 0 100
cm Weighted Average value provided for each map unit in the Mapunit Aggregated Attribute table Soil
erodibility (K) factor was assigned using the Kf value provided for the top horizon in the Horizon table for each
map unit Dominant hydrologic soil group was assigned by using the Hydrologic Group Dominant Conditions
value provided for each map unit in the Mapunit Aggregated Attribute table Organic matter content is not
currently used by the model and was not assigned a value
3 2 3 Curve Numbers
GWLF computes runoff from each land use class using the SCS Curve Number Equation (Ogrosky and Mockus
1964 SCS 1986) Curve Numbers (CNs) an essential component to this method were assigned to each land use
class by relating the individual classes to a cover type and hydrologic condition category described in Soil
Conservation Service Technical Release 55 (SCS 1986) CNs assignments are presented in Table 10 The GWLF
model used in this analysis only accepts one CN per land use class As such a single area weighted average CN
was calculated for each land use class of each HU based on the area of the land use class overlying the four
hydrologic soil groups The resultant average CN value was provided to GWLF
Table 10 Quantitative ICE Land Use Class CN
Quarititative ICE Land Use Classes
Open Water 100
ck,
6
100
100
100
Developed Open Space
39
61
74
80
Developed Low Intensity
57
72
81
86
Developed Medium Intensity
77
85
90
92
Developed High Intensity
89
92
94
95
Barren Land (Rock /Sand /Clay)
77
86
91
94
Deciduous Forest
30
55
70
77
Evergreen Forest
30
55
70
77
Mixed Forest
30
55
70
77
Shrub /Scrub
30
48
65
73
Grassland /Herbaceous
39
61
74
80
Pasture /Hay
49
69
79
84
Cultivated Crops
67
78
85
89
Woody Wetlands
36
60
73
79
Emergent Herbaceous Wetlands
49
69
79
84
3 2 4 Streams
The stream layer was derived from the National Hydrography Dataset (NHD) (USGS 2010) by extracting the high
resolution NHD flow lines from the prestaged Edisto Santee subregion The merged streams were then clipped
to the Study Area boundary The clipped streams were used in delineating the extent of existing riparian
buffers
3 2 5 Weather Stations
The location of weather stations with daily temperature (maximum and minimum) and precipitation records for
the period 1999 2010 were retrieved from State Climate Office of North Carolina (SCO) (SCO 2011) Weather
data from the Gastonia Municipal Airport (KAKH) in Gaston County was formatted for use by BasinSim
16

Gaston East West Connector Water Quality Analysis
August2011 - Draft
3 2 9 Septic Areas
GIS layers describing the extent of current and future sewer systems for the Study Area were supplied by Berger
(Tidd Louis Berger Group Inc personal communication 10/15/2010) Current septic service was assumed to
occupy the portion of the Study Area not served by the current sewer system and likewise for the future septic
service The population served by current and future septic systems was derived from population data supplied
by Berger (Tidd Louis Berger Group Inc personal communication 1/10/2011) The septic population estimates
assumed that the Project will not make southern Gaston County more attractive to the types of facilities
counted as group quarters (i a college dorms prisons nursing homes etc ) and that the future group quarters
population is the same in the No Build and Build scenarios The group quarters facilities are assumed to be
distributed proportional to land area for TAZs only partially contained within the Study Area Population in
households was assumed to take into account the trend of decreasing household sizes over time in the
forecasts Therefore the future population in the Study Area is based on the relationship between future
population in households and future households in Metrolina Travel Demand Model estimates The analysis
assumes no changes to septic areas between the future land use scenarios
3 2 10 Best Management Practice (BMP) Implementation
The BasinSim GWLF build does not account for pollutant load reductions provided by BMPs
For this study pollutant load reductions attributable to riparian buffers (buffers) BMPs were instead accounted
for in a post processing effort in which GWLF calculated TN TP and TSS loads for a given HU were reduced
according to the existing buffer characteristics of the HU The implementation of the buffer post processing
calculations is described below
Existing buffers were delineated and characterized in portions of the Study Area with legally protected buffers
such as the main stem of the Catawba River The process was initiated by identifying buffer regulations in the
various planning jurisdictions of the Study Area Table 12 summarizes the Study Area buffer regulations Using
GIS the stream network represented by the NHD flowlines was buffered based on the buffer requirements
applicable to the stream location The resulting buffer layer establishes the extent of regulated buffers in the
Study Area However the buffer layer does not necessarily reflect the existing extent of intact buffers To
delineate the existing extent of intact buffers the buffer layer was overlaid on 2009 National Agriculture
Imagery Program (NAIP) aerial photography (USDA 2009a 2009b 2009c) Areas of disturbed buffer were
removed from the buffer layer leaving only intact buffers within regulated buffer areas The final buffer layer
represents the Baseline Condition buffer extent
It should be emphasized that only buffers in areas with legal protection were delineated Further the buffers
were only delineated to their legally protected width For example a riparian buffers along the Catawba River
would only be delineated to 50 feet even if the vegetated area extends beyond 50 feet This judgment was
made because the vegetated area beyond 50 feet is not protected and consequently not guaranteed to persist
in the 2035 No Build and 2035 PA scenarios
18

'Catawba River Basin Buffer Rules (15a ncac 02b 0243)
2Gaston County NC (2011)
3Mecklenburg County NC (1999)
4York County SC (2009)
Gaston East West Connector Water Quality Analysis
August 2011 - Draft
'ilurisdictional Area
Table 12 Study Area Regulated Buffer Widths
Criteria
Willi
Main Catawba River stem and the 7 main stem
Catawba River'
lakes below Lake James south to the NC /SC
50
border
WS III 1 dwelling units (DU) /ac or 12/ built
Gaston County NC2
upon area (low density) 0 5 mile critical area
30
perennial stream
Gaston County NC2
WS III 1 du /0 5 ac or 24% built upon area (low
30
density) Rest of watershed perennial stream
Gaston County NC2
WS IV 1 du /0 5 ac or 24/o built upon area (low
30
density) 0 5 mile critical area perennial stream
WS IV (1 du /0 5 ac or 24/ built upon area with
Gaston County NC2
curb and gutter) or (1 du /0 33 ac or 36/ built
30
upon area with no curb and gutter) Protected
Area perennial stream
Gaston County NC2
WS III 12 30% built upon area 0 5 mile critical
100
area perennial stream
Gaston County NC2
WS III 24 50/ built upon area Rest of
100
watershed perennial stream
Gaston County NC2
WS IV 24 50/ built upon area 0 5 mile critical
100
area perennial stream
Gaston County NC2
WS IV 24 70/ built upon area 0 5 mile critical
100
area perennial stream
Mecklenburg County NC3
Drainage area >= 100 acres
35
Mecklenburg County NC3
Drainage area >= 300 acres
50
Mecklenburg County NC3
Drainage area >= 640 acres
100 + 50/ floodplain fringe
York County SC4
Lake Wylie
50
York County SC4
Catawba River
100
Perennial streams draining directly to the
York County SC4
Catawba River or Lake Wylie Perennial streams
50
are defined as solid blue lines on USGS
topographic maps
19

Gaston East West Connector Water Quality Analysis
August 2011 -Draft
The buffered stream fraction and average buffer width was determined for each Study Area HU using the
Baseline Condition buffer extent described above The buffered stream fraction was calculated as follows
Buffered Stream Fraction = Buffered Stream Length in HU
Total Stream Length in HU
The NHD flowlines were used to determine the total HU stream length value in the above equation
The average buffer width in each HU was calculated as a weighted average based on the length of the buffered
stream segments Again only buffers in areas with legal protection were considered _Average buffer widths
calculated for the HUs ranged from 0 feet to 76 feet
The buffered stream fraction and average buffer width determined for each HU are presented in Table 13 The
average buffer width for Beaverdam Creek Catawba River is reported as 0 feet because no buffer protection
ordinances are in effect in this HU
Table 13 Averaee Buffer Width by HU
12-digit
Hydrologic Unit
Code
030501011404
Subwatershed Name
Paw Creek Lake Wylie
Buffer Width
74
Buffered
Stream
Fraction
0 104
030501011405
Fites Creek Catawba River
57
0 033
030501011406
Lake Wylie Catawba River
66
0 010
030501011501
Upper Crowders Creek
22
0 023
030501011502
Catawba Creek
50
0 001
030501011503
Beaverdam Creek Catawba River
0
Not Applicable
0030501011504
Lower Crowders Creek
50
0 002
030501011505
Mill Creek Lake Wylie
76
0 012
030501020605
Duharts Creek South Fork Catawba River
50
0 005
The NCDWQ Stormwater Best Management Practices Manual (2007c) provides pollutant reduction efficiencies
for 50 foot riparian buffers (Table 14) The reduction efficiencies were applied in the post processing of the
GWLF calculated TN TP and TSS loads to account for pollutant reduction by buffers as follows
Reduced Pollutant Loading = GWLF Loading x Buffered Stream Fraction x Reduction Efficiency
Pollutant reduction by buffers was only considered for HUs with an average buffer width of 50 feet or greater
Upper Crowders Creek and Beaverdam Creek Catawba River HUs do not meet this criterion As such the GWLF
calculated loads for these HUs were not modified
Table 14 GWLF Buffer Reduction Efficiencies
20

Gaston East West Connector Water Quality Analysis
August 2011 -Draft
Riparian buffers were the only BMP considered in this analysis Implementation of other BMPs — bioretention
basins stormwater ponds grass swales etc — requires site specific information unavailable at this time Atkins
believes that without site specific information simulating such BMPs for developed areas in the future land use
scenarios amounts to applying a blanket pollutant loading reduction to all runoff from these areas Substantial
pollutant load reductions beyond those provided by the simulated riparian buffers could be realized if the EPA
Phase I and II Stormwater Rules in effect through 99 percent of the Study Area and locally mandated
stormwater treatment requirements are enforced
3 3 Model Calibration
A modeling analysis of any type may include a calibration procedure in which model parameters are adjusted to
achieve a best fit model or a model that best accords with observed data This process occurs in two steps
calibration and validation Before either is performed the observed data record is split into corresponding
calibration and validation periods The observed record for model calibration consisted of daily streamflow
(USGS 2010) at USGS gage 02145642 Crowders Creek (RD 1104) near Clover SC in the Lower Crowders Creek
watershed (HU 030501011504) for the period 10/1/1999 through 9/30/2003 Missing observations (July 11
2000 and 17 dates in August 2000) were replaced with streamflow for same day in 2001
Since the headwaters of Crowders Creek are also contained within the Study Area (Upper Crowders Creek HU)
Upper and Lower Crowders Creek were modeled and their output combined to compare to the observed
streamflow from the USGS gage GWLF reports streamflow in depth (centimeters) over the modeled area As
such total catchment streamflow was calculated as the area weighted average of the two watersheds This
approach uses area to scale the contribution of each watershed to the total streamflow Pollutant loadings were
not calibrated due to the lack of adequate monitoring data
The goal of the calibration effort for this analysis was to produce the best fit between modeled monthly
streamflow and observed monthly streamflow for the validation period The observed period of record was
divided evenly to establish the calibration (10/1/1999 through 9/30/2001) and validation periods (10/1/2001
through 9/30/2003) During calibration model parameters are adjusted within reasonable ranges until the
model results best fit the observed data of the calibration period The performance of the calibrated model is
then tested in the validation step by executing the model for the validation period and comparing the results to
observed data (EPA 2008) In watershed modeling studies the scope of the calibration effort depends in part on
the nature of the analysis and the availability of observed data Comparative analysis such as one the described
in this report often do not require a rigorous calibration effort as model error is expected to affect the study
scenarios equally
Calibration involved adjusting the GWLF parameters of the Upper and Lower Crowders Creek watershed models
to achieve better agreement between the model monthly streamflow and observed streamflow
Evapotranspiration and seepage coefficient parameters were adjusted during calibration Dai et al (2000)
recommended calibrating streamflow by adjusting the seepage parameters Seepage flow in GWLF represents
the water lost to the deep saturated zone (aquifer) and it may remain in the aquifer or exit the aquifer in areas
other than the watershed being studied The final parameter values are listed in Appendix B
The Nash Sutcliffe statistic (Nash and Sutcliffe 1970) a goodness of fit statistic recommended by the American
Society of Civil Engineers (1993) for hydrologic studies was used to evaluate the fit of the modeled streamflow
to observed stream The Nash Sutcliffe statistic (N S value) can range from oo to 1 The statistic measures the
models predictive performance relative to the mean of the observed data A value of 1 indicates a perfect fit
while a value of 0 indicates the model is predicting no better than mean of the observed data
21

Gaston East West Connector Water Quality Analysis
August 2011 - Draft
Modeled streamflows produced for Upper and Lower Crowders Creek watersheds correlated poorly with the
observed monthly streamflow (N S value = 0 26) for the calibration period Low flows during the period made
the calibration difficult The root mean square error (RMSE) between the modeled and observed monthly
streamflows for the calibration watershed was 0 9 cm however modeled streamflow did not provide a
satisfactory fit for the calibration period (Moriasi et al 2007) RMSE observations standard deviation ratio (RSR
= 0 84) (Moriasi et al 2007) was relatively small indicating that while the RMSE was small low flow rates were
the mayor reason and RSR was within acceptable limits Percent bias (PBIAS = 37) measures the average
tendency of the simulated data to be smaller than their observed counterparts and indicates that the
underestimation provides an unsatisfactory fit Modeled streamflow generally replicated the observed
streamflow response peaks and valleys (Figure 2)
Modeled streamflows for the validation period correlated well with the observed monthly streamflow (N S value
= 0 89) The RMSE between the modeled and observed monthly streamflows for the calibration watershed was
14 cm RSR was acceptably small (0 33) PBIAS (0 18) indicates minimal underestimation Modeled streamflow
provided a satisfactory fit for the validation period (Moriasi et al 2007)
Modeled monthly flows are plotted against the observed monthly streamflows of the calibration and validation
periods in Figure 2 monthly precipitation is plotted along the top axis In general the peaks of the modeled
streamflow align with the observed streamflow in terms of magnitude and duration although the amplitudes of
the modeled peaks are often larger than those of the observed streamflow in the later portion of the calibration
period The monthly streamflow values estimated by the final calibration and validation models are plotted in
Figure 2
Ultimately it was concluded the watershed models constructed for the Upper and Lower Crowders Creek
watersheds performed adequately well in calibration and validation procedures The ET and seepage coefficient
parameter values used in the best fit models were incorporated in the watershed models constructed for the
nine 12 digit HUs composing the Study Area
22

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Gaston East West Connector Water Quality Analysis
August 2011 - Draft
Calibration Period 10/1/1999 through 9/31/2001
Observed Monthly Streamflow vs Modeled Streamflow
Precipitation — Observed Streamflow - Modeled Flow
Validation Period 10/1/2001 through 9/31/2003
Observed Monthly Strearnflow vs Modeled Streamflow
0
— .— 10
L0 Precipitation —Observed Streamflow ---*---Modeled Flow
20
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4 0 RESULTS AND DISCUSSION
GWLF was run for three land use scenarios Baseline Condition 2035 No Build and 2035 PA Between scenarios
land use was modified to reflect forecasted land use conversions Other input parameters (Appendix B)
remained constant for all modeled scenarios Simulations were run for two years using weather data for the
period 2008 to 2010
Runoff and loading rates of TN TP and TSS (referred to cumulatively as pollutants ) vary as land use patterns
change within the Study Area In both future scenarios increased coverage by impervious surfaces resulted in
increases in runoff These results are expected as increased urbanization occurs Higher pollutant loads are
anticipated as currently undeveloped unmanaged land use categories (namely forest lands) are converted to
residential commercial and industrial categories Nutrient export loads from forest lands are significantly less
than export loads from commercial and industrial parcels The change from undeveloped but managed land use
categories (agricultural land and pasture) to developed land use categories can result in decreased pollutant
loads but increases in runoff
In reviewing the GWLF model output patterns emerged between the calculated runoff and nutrient loading
rates and the average HU CN nitrogen buildup rate for urban areas and phosphorus buildup rate for urban
areas The CN and nitrogen and phosphorus buildup rates for urban areas are parameters considered by GWLF
In calculating runoff TN loading and TP loading respectively In general runoff increases as CN Increases TN
loading Increases as the nitrogen buildup rate Increases and TP Increases as the phosphorus buildup rate
Increases These observations are a gross simplification of the relationship between land use and runoff and
pollutant loads yet the pattern generally bears out In the model results reported In Tables 17 19 Table 15
23

Gaston East West Connector Water Quality Analysis
August 2011 - Draft
presents the CN nitrogen build rates and phosphorus buildup rates for the Baseline 2035 No Build and 2035
PA scenarios The values are helpful in explaining differences between the 2035 No Build and 2035 PA scenarios
and will be referred to throughout this section
A similar trend was not found for the TSS loading rate The TSS loading rate is determined by a more
complicated relationship of model parameters which makes it difficult to isolate any one parameter as a
controlling factor
The results of the water quality analysis are discussed individually for the three modeled land use scenarios
Tables comparing the streamflow and pollutant loadings for the three scenarios are provided (Tables 17 20)
The presentation format of the tables is discussed in section 4 4 Analysis results are graphically presented in
Figures A4 A6 in Appendix A
24

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Gaston East West Connector Water Quality Analysis
August 2011 - Draft
4 1 Baseline Condition
The Study Area primarily consists of suburban and rural land uses (Berger 2011) Urban and suburban land uses
are concentrated around Gastonia NC in the north central portion of the Study Area — an area corresponding to
the Catawba Creek Duharts Creek South Fork Catawba River and Upper Crowders Creek HUs In the
northeastern portion of the Study Area Belmont NC and the western extent of Charlotte NC impart an urban
character to the Fites Creek Catawba River and Paw Creek Lake Wylie HUs (Figures Aland A2 Appendix A)
HUs containing a high percentage of impervious surface as described in Berger (2011) and high average CN
value (Table 15) were found to produce the most runoff on a per acre basis (e g Lake Wylie Catawba River
Fites Creek Catawba River and Paw Creek Lake Wylie) As expected these HUs correspond to the urban areas
of Belmont Gastonia and Charlotte NC The Mill Creek Lake Wylie HU was found to have the second highest
runoff rate despite having only the third highest percentage of impervious surface This result is explained by
the large proportion of the HU comprised by Lake Wylie In the GWLF model water surfaces such as lakes yield
high amounts of runoff because unlike soils water is not considered to have any absorptive capacity In effect
all precipitation falling on a waterbody is treated as runoff
High rates of TN loading may be attributable to several factors agricultural land high density urban land uses
septic systems and point source discharges In the case of the Duharts Creek South Fork Catawba River HU the
high TN loading rate is caused by the presence of septic systems and multiple point source dischargers three of
which are waste water treatment plants (WWTPs) The Fites Creek Catawba River HU has the second highest TN
and TP loading rates of the Study Area Here the high loadings are attributable to a combination of two
WWTPs urban runoff and septic systems Compared to other HUs the TN loading rate from the Paw Creek
Lake Wylie HU is seemingly lower than expected the HU has the highest percentage of urban land uses but
generates a relatively low amount of TN Other HUs with lower concentrations of urban land use exceed the TN
loading rate of the Paw Creek Lake Wylie HU because of the presence of septic systems
The pattern of TP loading rates in the HUs closely follows the average phosphorus buildup for urban areas the
TP loading rate increases as the average phosphorus buildup rate increases Deviations from this relationship
are the result of point source dischargers namely WWTPs For instance the Paw Creek Lake Wylie HU has the
highest average phosphorus buildup rate and produces the highest rate of TP loading among the HUs without
WWTPs The Duharts Creek South Fork Catawba River and Fites Creek Catawba River HUs have high average
phosphorus buildup rates and both contain WWTPs Discharge from the WWTPs causes these HUs to surpass
the TP loading rate of the Paw Creek Lake Wylie HU
TSS is calculated as a proportion of overland erosion by GWLF Overland erosion is related to runoff but is also
influenced by watershed specific conditions such as slope soil properties and land use practices Agricultural
lands used for crop cultivation in particular are major generators of overland erosion In urban areas
developed open space and developed low intensity land uses are the largest generators of overland erosion but
produce much less erosion than agricultural land uses Accordingly these land uses have the comparatively
high TSS loading rates Due to watershed conditions and a relatively high composition of developed open space
and developed low intensity land uses the Duharts Creek South Fork Catawba River Fites Creek Catawba River
and Upper Crowders Creek produce the highest TSS concentrations The Paw Creek Lake Wylie HU is notable
here because the high percentage of developed open space and developed low intensity land uses would
suggest that the HU rank as one of the highest TSS exporters However the slopes and soil properties of the HU
are less conducive to erosion and serve to moderate the erosive potential of these land uses

Gaston East West Connector Water Quality Analysis
August 2011 -Draft
4 2 2035 No Build
Development is predicted to increase throughout the Study Area The greatest increase in households and
residential land use acreage is expected around Gastonia NC in the Catawba Creek Duharts Creek South Fork
Catawba River and Upper Crowders Creek HUs (Figure A2 Appendix A) The attendant increase in impervious
urea results in increased modeled runoff and TN and TP loading rates across all HUs In contrast TSS loading
gates decrease in all but the Beaverdam Creek Catawba River HU as a result of the conversion of agricultural
land uses which generate large amounts of overland erosion relative to urban land uses
The mayor contributors of runoff do not change between the Baseline and 2035 No Build scenario HUs with
high impervious percentages and high average CN values (Table 15) continue to contribute high runoff (Lake
Wylie Catawba River Fites Creek Catawba River and Paw Creek Lake Wylie) The Paw Creek Lake Wylie and
Upper Crowders Creek HUs are projected to experience relatively large increases in urban land uses under the
2035 No Build scenario Consequently these two HUs are predicted to experience the greatest increase in
runoff
The largest TN exporters are unchanged in the 2035 No Build Scenario the Duharts Creek South Fork Catawba
River HU remains the largest exporter of TN and the Fites Creek Catawba River and Upper Crowders Creek HUs
are also still among the largest exporters However in a departure from the Baseline scenario the Paw Creek
Lake Wylie and Lake Wylie Catawba _River_HUs =trans it ion _fro .m low to moderate TN_ exporters These HUs
experience the largest increase in TN_loading rate as a result of relatively high increases in urban land uses
A similar pattern was observed for the TP loading, rates as well _The Duharts Creek South Fork Catawba River HU
is still projected to have the largest TP loading rate dust as in the Baseline scenario Yet as explained above for
TN increases in urban land use cause the Paw Creek Lake Wylie and Lake Wylie Catawba River HUs to
experience the greatest increase in TP loading rate
Six of the nine HUs experience an increase in TSS loading rate as a result of the conversion of less erosive
undisturbed land uses namely forestt c, mor_e_erosive developed land uses The overall pattern of TSS expos ers°
changes only for the highest generators - Upper Crowders Creek Duharts Creek South Fork Catawba River HUs
and Fites Creek Catawba River
43 2035 Preferred Alternative (PA)
The land use condition captured by the 2035 PA scenario is differentiated from the 2035 No Build scenario by
construction of the Project In aggregate The 2035 PA scenario would see approximately 1 100 additional acres
of residential development and approximately 100 fewer acres of commercial /industrial /office development in
the Study Area as compared to the 20_35 No Build scenario The increase in residential development is expected
to produce 3 300 additional households Most of the resident development (70 percent) is forecasted to occur
in the Catawba Creek and Lower Crowders HUs (Berger 2011) Additionally 1500 acres of direct impacts
resulting Gaston East West Connector right of way are expected Direct impacts will be distributed among the
six HUs traversed by the proposed alignment Catawba Creek Duharts Creek South Fork Catawba River Lake
Wylie Catawba River Lower Crowders Creek Mill Creek Lake Wylie and Upper Crowders Creek HUs
Five of the nine Study Area HUs add impervious surface cover in the 2035 PA scenario (Berger 2011) Beaverdam
Creek Catawba Creek Lake Wylie Catawba River Lower Crowders Creek and Mill Creek Lake Wylie The
Catawba Creek and_Lower Crowders Creek experience the largest area of change between the 2035 No Build
and the 2035 PA scenarios Of these HUs Catawba Creek is projected to have largest increase in development
density as measured 6y—change in impervious surface coverage (Berger 2011) and further evidenced by the
increase in the 2035 No Build and 2035 PA CN values reported in Table 15
27
`S

Gaston East West Connector Water Quality Analysis
August 2011 - Draft
The HU runoff and pollutant loading rates in the 2035 PA scenario for the most part mirror the pattern observed
for the 2035 No Build scenario Lake Wylie Catawba River is still the largest generator of runoff Duharts Creek
South Fork Catawba River still has the highest TN loading rate and so on While the relationship among the HUs
remains unchanged in terms of which HUs generate the largest runoff and nutrient exports the predicted runoff
and nutrient loading rates have changed Differences in runoff and pollutant loading rates observed between
the 2035 PA scenario and 2035 No Build scenarios reflect changes in development density and the type of land
use converted Specifically differences in runoff and nutrient loads (TN and TP) are caused by increased
impervious surface coverage in the 2035 PA scenario HUs with large increases in the highest density
development are projected to experience the largest increase in runoff and nutrient loading The Catawba
Creek HU which experiences the largest increase in impervious surface coverage demonstrates this point
Catawba Creek is projected to have the largest the increase in nutrient loads and second largest increase in
runoff
It is more difficult to identify such a simple relationship between TSS loading rates and other model parameters
as TSS loading trends are confounded by the number of factors involved in computing sediment yield Sediment
transport capacity is proportional to runoff and watershed size as reflected in the sediment delivery ratio
Runoff and erosion change between the No Build and Build scenarios The degree in land use change is reflected
in the erosion load factors however the magnitude of that change does not directly map to the magnitude of
change in TSS load
4 4 Results Tables
The water quality analysis results are compared in the series of tables that follow (Tables 17 20) Each table
presents the results of a single experimental parameter for the nine HUs composing the Study Area The
percent difference between the 2035 No Build and 2035 PA results are reported in the rightmost column of the
tables with the heading 2035 PA — 2035 No Build The values in this column quantify the water quality effects
of the Project as measured by this analysis
GWLF consumes the data listed in Table 8 to produce runoff and pollutant loads The number of decimal places
and significant figures generally used by GWLF for reporting various model outputs are displayed in Table 16
The significant figures listed in Table 16 determined the significant figures used to report the analysis results in
Tables 17 20 Some pollutant loads are presented as annual loading per unit HU area —In-these—cases pollutant,
load value is divided by the HU_area which has fewer significant figures The resulting quotient should contain
five significant figures as the HU area does However reported values have been truncated to three or four
significant figures (i a three decimal places) to avoid excessively long decimal values
Table 16 Renorted Sienificant Fieures
Parameter (units)
Runoff (centimeters/ year)
Decimal Places
2
Significant Figures
5
Total Nitrogen (tons /year)
4
7
Total Phosphorus (tons /year)
4
6
Total Suspended Sediment
(ton x 1000 /year)
1
5
Area (hectares)
1
5
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Gaston East West Connector Water Quality Analysis
August 2011 - Draft
5 0 CONCLUSIONS
The water quality analysis described in this report was performed in response to the Resource Agencies request
for additional quantitative data on the Preferred Alternative particularly NCDWQ s request for additional
modeling of pollutant loadings attributable to the Project As such the analysis sought to determine how
estimated induced land use changes resulting from the Project may affect water quality throughout the 265
square mile Study Area defined for the analysis
The analysis was performed by constructing watershed models for nine 12 digit hydrologic units (HUs)
composing the Study Area (Figure A2 Appendix A) using the BasinSim build of GLWF Model estimates of annual
runoff and annual overland pollutant loadings of total nitrogen (TN) total phosphorus (TP) and total suspended
sediment (TSS) loads produced from three land use scenarios - Baseline Condition 2035 No Build and 2035 PA
(Table 1) - were reviewed to assess the Project effects Specifically model results of the 2035 No Build and
2035 PA scenarios were compared
Five of the nine HUs composing the Study Area contain streams Qr waterbodies on the 2010 North Carolina or
South Carolina 303'(d) list (NCDWQ 2010a SCDHEC 2010) (Figure 2A- Appgndix_A) Catawba Creek Duharts
Creek South Fork Catawba River Lower Crowders Creek Mill Creek Lake Wylie and Upper Crowders Creek The
Pro— c"t aahTnment intersects all five HUs Further interchanges are planned in all five HUs The watershed
model results for these five HUs indicate increased runoff and TN and TP loads in the 2035 PA scenario
compared to the 2035 No Build scenario In contrast a decrease in TSS load is predicted for four of the five HUs
the exception being the Upper Crowders Creek HU Of the five HUs the Catawba Creek HU experiences the
largest indirect effects of the Pr'oject the HU incurs the greatest increase in urban land use and in turn the
largest increase-in-impervious surface coverage —As a result the - Catawba Creek HU is projected to have the
great�ease_s__in_r_unotf and nutrient loading rates
For the Study Area as a whole all nine HUs are anticipated to experience some degree of direct or indirect
effects from the Project Direct effects result from additional paved surface and right of way associated with
the Project alignment Indirect effects are in the form of increased residential development or
commercial /industrial /office development The result of these effects are apparent in the increases in runoff
and nutrient loading rates projected for all nine HUs As mentioned above the Catawba Creek HU experiences
the largest indirect effect and is projected to have the largest increase in runoff and nutrient loadings Over 80
percent of the land consumed by the direct and indirect effects is forecasted to come from forest and pasture
lands
Lastly several further points warrant mentioning First the analysis documented in this report was not
conducted for the purpose of predicting the specific amount of pollutants delivered at the outlet of each
modeled HU Rather the aim of the analysis was to determine the magnitude of runoff and pollutant loading
change between the 2035 No Build and 2035 PA scenarios These measurements indicate the trend of water
quality over time in each HU and the Study Area as a whole And second in terms of BMPs the analysis only
considered riparian buffers No site specific BMPs such as bioretention basins stormwater ponds grass
swales etc are accounted for in the results Consequently the watershed model overestimates pollutant _
loadings from areas that would otherwise - receive stormwater treatment Site specific BMPs were omitted due
to� a lack information regarding future development However the three of the four counties intersected by the
Study Area - Gaston and Mecklenburg Counties NC and York County SC - are NPDES Phase II communities
Under this designation the counties must require land disturbances greater than or equal to 1 acre to
implement runoff and pollutant reduction measures (USEPA 2005) Compliance with Phase II rules would likely
33

Gaston East West Connector Water Quality Analysis
August 2011 -Draft
result in reduced runoff and nutrient loading rates compared to those produced by the modeled 2035 No Build
and 2035 PA scenarios
34

Gaston East West Connector Water Quality Analysis
August 2011 - Draft
6 0 REFERENCES
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Management Committee Irrigation and Drainage Division 1993 Criteria for evaluation of watershed
models Journal of Irrigation and Drainage Engineering 199(3)
Beutow W S 2002 On site Wastewater Nitrogen Contributions to a Shallow Aquifer and Adjacent Stream MS
Thesis North Carolina State University Department of Soil Science Raleigh NC
Boyle John F Andy J Plater Claire Mayers Simon D Turner Rob W Stroud and Jerry E Weber 2011 Land
use soil erosion and sediment yield at Pinto Lake California comparison of a simplified LISLE model
with the lake sediment record Journal of Paleolimnology Volume 45 Number 2 Pages 199 212
Dai T R L Wetzel T R L Christensen and E A Lewis 2000 BasinSim 10 A Windows Based Watershed
Modeling Package User s Guide Virginia Institute of Marine Science College of William and Mary
Gloucester Point VA
Evans B M D W Lehning K J Corradini G W Petersen E Nizeyimana J M Hamlett P D Robillard and R
L Day 2002 A comprehensive GIS based modeling approach for predicting nutrient loads in
watersheds Journal of Spatial Hydrology 2(2)
Evans B M and K J Corradini 2007 AVGWLF Version 7 0 A Guide to Creating Software Compatible Data Sets
Penn State Institutes of the Environment 34 pp
Evans B M D W Lehning and K J Corradini 2008 AVGWLF Version 7 1 Users Guide Penn State Institutes of
the Environment 114 pp
Evans B M D W Lehning K J Corradini G W Petersen E Nizeyimana J M Hamlett P D Robillard and R
L Day 2002 A comprehensive GIS based modeling approach for predicting nutrient loads in
watersheds Journal of Spatial Hydrology 2(2)
Fu B W Zha L Chen Q J Zhang Y H Lu H Gulinck and J Poesen 2005 Assessment of soil erosion at larger
watershed scale using RUSLE and GIS a case study in the loess plateau of China Land Degradation &
Development 16 73 -85
Gaston County North Carolina 2011 Gaston County Unified Development Ordinance Chapter 15 Watershed
Supply Watershed Regulations Available at http / /www gastongov com /departments /planning /udo
Haith D A and L L Shoemaker 1987 Generalized Watershed Loading Functions for Stream Flow Nutrients
Water Resources Bulletin 23(3) 471 478
Haith D R R Mandel and R S Wu 1992 GWLF Generalized Watershed Loading Functions User s Manual
Vers 2 0 Cornell University Ithaca NY
Haith D A 1993 RUNQUAL Runoff Quality from Development Sites Users Manual Dept Agricultural and Biol
Engineering Cornell University 34 pp
Hong B and D Swaney 2004 GWLFXL Users Manual (Online) Available at
http //www eeb cornell edu /biogeo /usgswri /GWLFXL /gwlfxl doc [May 2011]
35

Gaston East West Connector Water QualityAnalysis
August 2011 -Draft
Jackson C R J K Martin D S Leigh L T West 2005 A southeastern piedmont watershed sediment budget
evidence for a multi millennial agricultural legacy J Soil Water Consery 60 298 -310
King K W J C Balogh and R D Harmel 2007 Nutrient flux in storm water runoff and baseflow from managed
turf Environmental pollution 150 321 328
Lee K Y T R Fisher T E Jordan D L Correll and D E Weller 2000 Modeling the hydrochemistry of the
Choptank River Basin using GWLF and Arc /Info 1 Model calibration and validation Biogeochemistery
49 143 173
Mecklenburg County North Carolina 1999 Surface Water Improvement & Management (S W I M ) Oridance
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Gaston East West Connector Water Quality Analysis
August 2011 -Draft
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40

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Appendix D
Correspondence with N.C. Division of Water Quality Regarding
Analysis Methodology

pBskjol
an Atkins company
To: Polly Lespinasse, Brian Wrenn, Colin Mellor
From: Brad Allen
CC: Christy Shumate, Jennifer Harris, Jill Gurack, David O'Loughlin
Date: October 22, 2010; Updated
MEMORANDUM
Re: Minutes for Gaston ICE Water Quality Analyis Meeting with NCDWQ
Attendees:
• Polly Lespinasse (NCDWQ)
• Brain Wrenn (NCDWQ)
• Colin Mellor (NCDOT
• Dave O'Loughlin (PBS &J)
• Brad Allen (PBS &J)
On October 18, 2010, the above personnel from the NC Division of Water Quality (NCDWQ), NC
Department of Transportation (NCDOT), and PBS &J met at the NCDWQ Winston - Salem, NC office.
The purpose of the meeting was to discuss issues related to the Gaston East/West Connector (the
Project) indirect and cumulative effects (ICE) water quality analysis (Analysis).
The meeting started with PBS &J summarizing the status of the Analysis. PBS &J explained work had
begun to develop the Analysis methodology, but they had reached a point at which they would like to
receive NCDWQ's approval on several key elements of the proposed Analysis before moving forward.
The focus of the meeting was then turned to the following six questions identified by PBS &J as
requiring resolution.
1. Is it acceptable to use the quantitative ICE boundary for the Analysis?
The Gaston East -West Connector Quantitative Indirect and Cumulative Effects Analysis
(August 3, 2010) was prepared by Louis Berger Group. The report was posted on the
NCTA website and environmental resource and regulatory agencies were notified and
asked to review and comment. To date, no comments have been received.
2. Are the 12 -digit Hydrologic Units (HUs) acceptable reporting units for the Analysis results?
3. Is focusing the Analysis on non -point source nitrogen, phosphorus, and sediment
adequate for addressing regulatory agency concerns over the Project's ICE?
• Page 1

4. Is it acceptable to only consider the effect of riparian buffer best management
practices (BMPs) in the Analysis?
5. Is the resolution of the forecast -zone scale for which No Build and Build land use
forecasts are reported adequate for the Analysis?
6. Is PBS &J's recommended approach for processing the forecast data of the future
land use scenarios acceptable?
The resolution and discussion corresponding to each question are summarized below
1. Is it acceptable to use the quantitative ICE boundary for the Analysis?
Resolution: No resolution was reached during the meeting.
Resolution Update: Brian Wrenn of NCDWQ responded to this issue in an email on October 22,
2010. In the email, he requests that the Fites Creek - Catawba River 12 -digit hydrologic unit (HUC
30501011405) be included in the study area of the ICE quantitative land use and water quality analysis.
Brian's email is included at the end of this memorandum as a record of documentation.
NCDWQ had questions regarding the quantitative ICE boundary and requested to withhold comments
on the matter until those questions are answered . Specifically, NCDWQ questioned why the 12 -digit
HUs highlighted in green and marked with asterisks in the below figure were not included in the
quantitative ICE analysis. The point was made that both HUs are in the vicinity of the proposed
roadway alignment, and both appear to have open space available for development. Neither Colin nor
PBS &J could provide an answer, but agreed to find out why the HUs were not considered. PBS &J will
inform NCDWQ of the findings. At which time, NCDWQ will then provide an opinion on the suitability of
the quantitative ICE boundary for the Analysis.
• Page 2

In answer to NCDWQ's questions conceming the quantitative ICE boundary, PBS &J has identified that
sections 2.1.1 and 2.1.2 of the Gaston East -West Connector Quantitative Indirect and Cumulative
Effects Analysis explain the exclusion of the HUs. The content of both sections is provided below.
PBS &J requests that NCDWQ reply to indicate if the explanations are sufficient.
2.1.1 Gaston County
In Gaston County, a small portion of the northwest corner of the
qualitative ICE study area was removed, including the northern half of
Bessemer City and part of Gastonia. To the east of Gastonia, a portion of
Belmont and an adjacent unincorporated area along the I -85 corridor
was removed. The transportation modeling conducted for the project with
the Metrolina Travel Demand Model shows that the TAZs in these areas
would notexperience any substantial change in travel times as a result of
the Gaston East -West Connector and thus are unlikely to experience
growth pressures attributable to the project. The reason this area would
not experience substantial changes in accessibility is that it is already in
close proximity to 1 -85, which is the existing primary east -west roadway
and crossing of the Catawba River in Gaston County.
The study area was expanded to the north to include the entirety of the
Duharts Creek -South Fork Catawba River subwatershed
(030501020605). The expanded area includes parts of Gastonia, Lowell,
McAdenville, Ranlo and Spencer Mountain. This expansion of the study
area was made only for the purpose of including the entire watershed in
the study area, not because of accessibility changes in this area.
2.1.2 Mecklenburg County
In Mecklenburg County, the study area was expanded to include the
entire Paw Creek -Lake Wylie subwatershed (030501011404). Although
there are not substantial accessibility changes for this watershed, it does
contain part of two important No Build condition projects -- the Charlotte -
Douglas International Airport third runway and intermodal freight facility.
A portion of the study area to the east of 1 -485 was removed based on
the results of the projected travel time improvements being the greatest
around and to the east of the Gaston East -West Connector's interchange
with 1 -485. The subwatersheds in this location (030501030103- Upper
Sugar Creek and 030501030108- Steele Creek) are within a heavily
developed portion of the City of Charlotte and would be unlikely to
experience further environmental impacts from land use change because
the majority of the land in these subwatersheds is already developed.
While a portion of the Charlotte- Douglas International Airport is within the
Upper Sugar Creek watershed, the primary considerations in terms of
cumulative impacts (the new runway and the proposed intermodal
facility) are not and remain within the study area for the quantitative ICE
assessment.
Additionally, NCDWQ mentioned that a population of Carolina heelsplitter (Lasmigona decorata) may
have been found in the Catawba River; although, they were not sure of the details. The heelsplitter has
hereunto not been mentioned as an issue for this project. PBS &J will investigate this matter and inform
NCDWQ of the findings.
• Page 3

2 Are the 12 -digit HUs acceptable reporting units for the Analysis results?
Resolution: NCDWQ confirmed that the 12 -digit HUs are acceptable.
This question generated little discussion as it is typical to report the results of such analyses at the 14-
digit or 12 -digit HU scale.
3. Is focusing the Analysis on non -point source nitrogen, phosphorus, and sediment
adequate for addressing regulatory agency concerns over the Project's ICE?
Resolution: NCDWQ confirmed that modeling non -point source nitrogen, phosphorus, and sediment is
adequate, but the analysis may need to be expanded to include metal loadings.
The topic of metal pollution came up while reviewing impaired parameters for 303(d)- listed water s in
the project study area; the Catawba River is impaired in part for copper standard violations. Colin
mentioned metal pollution (such as copper and zinc) from highway runoff has become an issue of
increasing concern at NCDOT. Yet, no previous water quality analyses performed in support of
roadway ICE analyses in North Carolina have considered metal loadings. In fact, it is still unclear how
metals should be addressed in such analyses or if they should be considered at all. Colin and PBS &J
will continue to investigate the issue. NCDWQ recommended contacting Cindy Moore or Carol
Hollenkamp in NCDWQ's Aquatic Toxicology unit for assistance. Depending on the findings, the metal
loadings may be incorporated into the analysis.
4. Is it acceptable to only consider the effect of riparian buffer BMPs in the Analysis?
Resolution: NCDWQ confirmed that considering only riparian buffer BMPs is acceptable.
PBS &J discussed the uncertainty involved in modeling structural stormwater BMPs — bioretention
basins, stormwater ponds, grass swales, etc — for future land use conditions. It was PBS &J's
contention that such BMPs should not be considered in the water quality model. Instead, a qualitative
discussion of these BMPs will be provided in the Analysis report. NCDWQ agreed.
5. Is the resolution of the traffic analysis zone (TAZ) (or forecast -zone) scale for which No
Build and Build land use forecasts are reported adequate for the Analysis?
Resolution: NCDWQ confirmed that the forecast zones used to report the No Build and Build land use
forecasts were adequate. Further, NCDWQ requested that the Existing land use be aggregated to the
forecast -zones too. The purpose in normalizing all the land use datasets to the forecast zones is to
provide consistent reporting scale for all land use scenarios.
PBS &J discussed the format of the Existing, No Build, and Build land use datasets developed by the
Louis Berger Group. It was noted that the Existing land use was formatted as a spatially- explicit raster
dataset with a 30 -meter resolution. In contrast, the No Build and Build land use datasets are not
spatially explicit and are constructed at the much coarser resolution of the forecast zones. Because of
the varying resolutions of the land use datasets, separate techniques would need to be used to
generate model parameters and the reporting of results would differ too. NCDWQ expressed concern
over this seeming disparity between the Existing dataset and future land use forecasts, stating that it
creates doubt that a direct comparison of pollutant loadings can be made. Essentially, the Analysis
would not provide an "apples to apples" comparison if the land use datasets are not normalized to a
• Page 4

consistent scale. PBS &J and Colin acknowledged as much. Two solutions were then discussed: 1)
spatially - explicit future land use forecasts could be generated to match the format of the Existing
dataset or 2) the spatially - explicit Existing dataset could be aggregated to the forecast -zone scale to
match the format of the future land use forecasts. Ultimately, it was decided to pursue the second
option.
6. Is PBS &J's recommended approach for processing the forecast data of the
future land use scenarios acceptable?
Resolution: NCDWQ suggested the approach detailed in question 5 above.
NCDWQ, as well as Colin and PBS &J, felt that PBS &J's initial recommendation to process the lower
resolution future land use datasets in a different manner than the Existing dataset would introduce
unnecessary confusion into the Analysis and subsequent report. All attendees concluded an
alternative approach in which the Existing dataset would be aggregated to the forecast -zone scale to
match the lower resolution format of the future land use forecasts should be used. By processing the
Existing dataset to match the format of the future land use forecasts, the same techniques can be used
to calculate the water quality model parameters for all three land use scenarios. This will eliminate the
need to explain and justify the use of separate modeling techniques for the Existing and future land use
scenarios.
• Page 5

Allen, Thomas B
From: Wrenn, Brian
Sent: Friday, October 22, 2010 10:26 AM
To: Allen, Thomas B; Lespinasse, Polly; Mellor, Colin
Cc: jsgurak,; Shumate, Christy; Harris, Jennifer; O'Loughlin, David K
Subject: RE: Minutes for Gaston WQ Analysis Meeting
I have one comment regarding the minutes. For the explanation of excluding the watersheds in Gaston
Co. near Bessemer City, although I can understand the travel time savings will not be significantly
increased for the northern portion of the HUC, surely there will be some induced growth south of 85
and 29. 1 think this HUC should be included in the analysis. Several of the HUCs included in the analysis
have portions that will not experience significant travel time savings, but they are still part of the study
area. No reason for this HUC to be excluded. That being said, Polly holds the trump card in this, so if
she disagrees with me, I will concede.
Brian Wrenn
Transportation Permitting Unit, Supervisor
NC Division of Water Quality
brian.wrenn @ncdenr.gov
585 Waughtown Street
Winston - Salem, NC 27107 -2241
336 - 771 -4952 (Winston -Salem no.)
336 - 771 -4631 (Fax)
or
2321 Crabtree Blvd., Ste 250
Raleigh, NC 27103
919 - 733 -5715 (Raleigh no.)
919 - 733 -6893 (Raleigh Fax)
From: Allen, Thomas B [mailto:TBAllen @pbsj.com]
Sent: Friday, October 22, 2010 10:02 AM
To: Wrenn, Brian; Lespinasse, Polly; Mellor, Colin
Cc: jsgurak,; Shumate, Christy; Harris, Jennifer; O'Loughlin, David K
Subject: Minutes for Gaston WQ Analysis Meeting
Polly, Brian, Colin:
Please find attached the minutes for the Gaston East /West Connector water quality analysis meeting
held on October 18, 2010. Perhaps the largest outstanding question from the meeting was why were
12 -digit HUs 030501011405 (Fites Creek -Lake Wylie) and 030501030103 (Sugar Creek Headwaters)
excluded from the study area? An explanation to this question is provided in the minutes. Brian and
Polly, would you please review the explanation and let me know if it is sufficient. Feel free to contact
me if you have any further questions or comments.
Thanks,

Brad Allen, E.I.
Senior Scientist
PBSU - Mid - Atlantic Sciences
1616 E. Millbrook Road, Suite 310
Raleigh, NC 27609
Office: 919.876.6888 (Main)
Office: 919.431.5222 (Direct)
Fax: [phone]
[e-mail]
www.pbs'.com