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TABLE OF CONTENTS
UNION COUNTY, NORTH CAROLINA
TWELVE MILE CREEK WASTEWATER TREATMENT PLANT
PERFORMANCE EVALUATION
Page
EXECUTIVE SUMMARY
1.0 — Introduction 2
1.1 — Existing Facilities 2
1.2 — Effluent Quality Requirements 4
1.3 — Plant Performance Problems 4
2.0 — Wastewater Characterization 5
3.0 — Operations and Performance 6
4.0 — Process Modeling and Evaluation 9
4.1 — Process Evaluation 9
4.1.1. — Plant Recycle Streams 10
4.1.2. — Nitrified Recycle Rate 11
4.1.3.•— Dissolved Oxygen Return 11
4.1.4. — Readily Biodegradable Carbon 12
4.1.5. — Secondary Clarifier Blanket Level 13
4.1.6. — SRT Analysis and Optimization 14
4.1.7. — Chemical Phosphorus Removal 15
5.0 — Optimization of Existing Facilities 15
5.1 — Reduce Digester Decant Recycle 15
5.2 — SRT Optimization 16
5.3 — Reliable Solids Removal 16
5.4 — Chemical Phosphorus. Precipitation 17
5.5 — Solids Handling Optimization 17
6.0 — Required Capital Improvements 18
6.1 — Stand-by Power 18
6.2 — Supplemental Aeration 19
6.3 — Secondary Clarifier Flow Distribution and Solids Removal 19
6.4 — Optimization of Rotary Drum Thickener 19
7.0 — Anticipated Performance in Interim Period 20
APPENDICES
Appendix A — Flow and Load Analysis 21
Appendix B — Plant Operational Data 29
Union County
Twelve Mile Creek WWTP
Performance Evaluation
TOC

TABLE OF CONTENTS
UNION COUNTY, NORTH CAROLINA
TWELVE MILE CREEK WASTEWATER TREATMENT PLANT
PERFORMANCE EVALUATION
LIST OF TABLES
Page
1-1 — Process Design Criteria — Existing Facility 3
1-2 — Current Effluent Quality Requirements 4
2-1 — Historical Wastewater Characteristics 5
3-1 — SVI Percentile Values 9
4-1 — Maximum Month Conditions 10
5-1 — Recommended SRT Optimization 16
5-2 — RDT Operation — 2.5 MGD Design Flow — 5 Days per Week 17
5-3 — RDT Operation — 2.5 MGD Design Flow — 7 Days per Week 18
5-4 — Digester Capacity 18
A-1 — Historical Flows and Peaking Factors 22
A-2 — Annual Average Influent Concentrations 23
A-3 — Average Influent Ratios 24
A-4 — Historical Load Peaking Factors 24
A-5 — Historical Effluent Temperatures 27
Union County
Twelve Mile Creek WWTP
Performance Evaluation
TOC
ii

TABLE OF CONTENTS
UNION COUNTY, NORTH CAROLINA
TWELVE MILE CREEK WASTEWATER TREATMENT PLANT
CAPACITY EVALUATION
LIST OF FIGURES
Page
3-1 -- Effluent BOD5 and TSS Concentrations 6
3-2 — Effluent Nitrogen Concentrations 7
3-3 — Effluent Total Phosphorus Concentrations 8
4-1 — Effluent TP vs. Influent BOD:TP 12
4-2 — Effluent Phosphate vs. SRT 14
A-1 — Historical Influent Flows 23
A-2 — Influent BOD5 Concentration 25
A-3 — Influent TSS Concentration 25
A-4 — Influent Ammonia Concentration 26
A-5 — Influent Total Nitrogen Concentration 26
A-6 — Influent Total Phosphorus Concentration 27
A-7 — Wastewater Effluent Temperatures 28
B-1 — Historical MLSS Concentrations 30
B-2 — Historical Solids Retention Times 30
B-3 — Historical SVI 31
B-4 — Historical Oxidation Ditch Dissolved Oxygen 31
Union County
Twelve Mile Creek WWTP
Performance Evaluation
TOC
iii

TABLE OF CONTENTS
UNION COUNTY, NORTH CAROLINA
TWELVE MILE CREEK WASTEWATER TREATMENT PLANT
PERFORMANCE EVALUATION
LIST OF EXHIBITS
Following
Page
1-1 -- Site Plan 3
1-2 — Process Flow Schematic — Liquid Stream 3
1-3 — Process Flow Schematic — Solid Stream 3
Union County TOC
Twelve Mile Creek WWTP iv
Performance Evaluation

PERFORMANCE EVALUATION Twelve Mile Creek WWTP
EXECUTIVE SUMMARY
The Union County Public Works Department owns and operates the Twelve Mile Creek
Wastewater Treatment Plant (WWTP) located in Waxhaw, North Carolina. The facility is
currently permitted to discharge a maximum month flow of 2.5 mgd to Twelve Mile Creek and is
being expanded to a 6.0 mgd design capacity. This Performance Evaluation is to determine the
capabilities of the existing Twelve Mile Creek WWTP to reliably comply with the current NPDES
permit and identify any deficiencies that should be addressed to improve compliance. The
Twelve Mile Creek WWTP has recently had a number of permit compliance issues. This study
reviews the existing facilities and historical operational data, recommends how the efficiency of
the existing facilities can be maximized, and whether the WWTP requires additional capital
facilities to maintain reliable treatment and compliance with the NPDES permit.
The study indicates that the Twelve Mile Creek WWTP generally has sufficient process units of
sufficient size to reliably meet NPDES permit requirements. However, improvements are
recommended both in terms of operational approaches and in terms of capital facilities to
improve process reliability.
The Twelve Mile Creek WWTP has facilities in place to provide biological nitrogen and
phosphorus removal. However, increasing/variable flows and loads, operational issues and
deficiencies in the plant infrastructure have prevented the facility from being able to reliably
meet permitted effluent phosphorus requirements. The existing processes at the plant were
evaluated with respect to permit compliance with an emphasis upon optimization for
phosphorous removal since that permit parameter has been in continued violation. Several
operational changes can be made in order to optimize biological phosphorus removal and
improve process performance at the Twelve Mile Creek WWTP. The recommended process
modifications include:
• Reduce Digester Decant Recycle
• Optimization of Control of SRT
• Reliable Solids Removal
• Chemical Phosphorus Trim
Despite the recommended operational changes listed above, it is anticipated that the Twelve
Mile Creek WWTP will not reliably perform in compliance with the NPDES permit requirements
without making capital improvements. The recommended capital improvements include:
• Addition of Stand-by Power Facilities
• Installation of Additional Aeration Capacity
• Secondary Clarifier Flow Distribution and Solids Removal improvements
With these upgrades, it is anticipated that the plant will meet all current permit requirements on
a consistent year-round basis.
Union County
Twelve Mile Creek WWTP
Performance Evaluation
1

PERFORMANCE EVALUATION Twelve Mile Creek WWTP
1.0. Introduction
The Union County Public Works Department owns and operates the Twelve Mile Creek
Wastewater Treatment Plant (WWTP) located in Waxhaw, North Carolina. The facility is
currently permitted to discharge a maximum month flow of 2.5 mgd to Twelve Mile Creek. The
facility is also currently under construction to expand the design capacity to 6.0 mgd.
The purpose of this Performance Evaluation is to determine the capabilities of the existing
Twelve Mile Creek WWTP to reliably comply with the current NPDES permit and identify any
deficiencies that should be addressed to improve compliance. The Twelve Mile Creek WWTP
has recently had a number of permit compliance issues. This study will review the existing
facilities and historical operational data, recommends how the efficiency of the existing facilities
can be maximized, and whether the WWTP requires additional capital facilities to maintain
reliable treatment and compliance with the NPDES permit.
1.1. Existing Facilities
Raw influent enters the Twelve Mile Creek WWTP through a 48-inch main and is pumped from
the influent pump station to the headworks, where the flow is screened and grit is removed.
Plant recycle flows are also introduced at the headworks. Return activated sludge (RAS) is
introduced downstream of grit removal, and the combined influent/RAS flows by gravity to the
secondary process.
The Twelve Mile Creek WWTP has two Eimco Carrousel® A2Cm, Systems for biochemical
oxygen demand (BOD) removal and biological nutrient removal (BNR). The systems consist of
an oxidation ditch preceded by an anaerobic and anoxic zone. Aeration is provided via low
speed mechanical surface aerators. One 100-horsepower aerator is installed at each oxidation
ditch. It is reported that the existing aerators operate well below the rated motor horsepower.
Based on observations by plant staff, the aerator motors draw a maximum of 85 horsepower,
which substantially decreases the oxygen delivered to the system.
Nitrified recycle is returned from the oxidation ditch to the anoxic zone via an adjustable gate.
Two secondary clarifiers settle the mixed liquor suspended solids (MLSS) from the oxidation
ditches. RAS is pumped from a common sludge well back to the secondary process influent
pipe. Waste activated sludge (WAS) is pumped from the sludge well to aerobic digesters.
Secondary effluent is filtered through two traveling bridge filters, followed by ultraviolet (UV)
disinfection. Effluent is conveyed by gravity to a cascade aerator for re -aeration and ultimate
disposal to Twelve Mile Creek.
The solids handling facilities consist of three aerobic digesters. Aeration is provided through
coarse bubble diffusers. A rotary drum thickener is also installed at the facility. Sludge is
thickened in the digesters either by mechanical means (i.e., operating the rotary drum thickener)
or by gravity solids/liquid separation (Le., returning decant to the head of the plant). Sludge is
stored in the digesters until it is removed and hauled for disposal via land application. Solids
are typically removed from the facility four times per year.
Union County
Twelve Mile Creek WWTP
Performance Evaluation
2

PERFORMANCE EVALUATION Twelve Mile Creek WWTP
The layout of the existing facility is shown in Exhibit 1-1. Exhibits 1-2 and 1-3 present the liquid
stream and solids stream process flow schematics, respectively. Table 1-1 summarizes the key
process design criteria and existing facilities at the Twelve Mile Creek WWTP.
Table 1-1 — Process Design Criteria — Existing Facility
Design Parameter Design Value
Influent
Flow, mgd 2.5
BOD5, mg/L 250
TSS, mg/L 250
TKN, mg/L 40
TP, mg/L 8
Effluent
BOD5, mg/L
TSS, mg/L
NH3-N, mg/L
TN, mg/L
TP, mg/L
< 5.0
< 15
< 1.0
< 10
< 1.0
Anaerobic Basin Design
Number of Anaerobic Basins per Train Two
Anaerobic Volume per Train, MG 0.104
Number of Anaerobic Mixers per Train Two
Horsepower per Anaerobic Mixer, hp 5
Carrousel Basin Design
Number of Trains Two
Aerobic Volume per Train, MG 0.91
Anoxic Volume per Train, MG 0.23
Number of Aerators per Train One
Horsepower per Aerator, hp 100
Number of Anoxic Mixers per Train One
Horsepower per Anoxic Mixer, hp 10
Process Design
Aerobic SRT, days 15
Internal recycle, mgd 10
MLSS, mg/L 4,000
Sludge Production, lbs TSS/day 4,036
Secondary Clarifiers
Number of Clarifiers 2
Diameter, ft 70
Depth, ft 14
Total Area, ft2 7,697
Union County
Twelve Mile Creek WWTP
Performance Evaluation
3

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TWELVE MILE CREEK
PHOSPHORUS REMOVAL OPTIMIZATION STUDY
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PERFORMANCE EVALUATION Twelve Mile Creek WWTP
Effluent Filters
Number of Filters 2
Type Traveling Bridge
Total Area, ft2 864
Average Hydraulic Loading Rate, gpm/ft2 2.0
Peak Hydraulic Loading Rate, gpmlft2 5.0
Solids Handling
Number of Aerobic Digesters 3
Digester Nos. 1 and 2 Volume each, MG 0.244
Digester No. 3 Volume, MG 1.069
Total Digester Volume, MG 1.557
Rotary Drum Thickener Capacity, gpm 200
1.2. Effluent Quality Requirements
The Twelve Mile Creek WWTP is currently permitted by the North Carolina Department of
Environment and Natural Resources (NCDENR) Division of Water Quality (DEQ) to discharge a
maximum monthly -average daily flow (MMADF) of 2.5 mgd of treated effluent to Twelve Mile
Creek. The discharge is permitted through National Pollutant Discharge Elimination System
(NPDES) P,ermit Number NC0085359. The permit was effective on November 1, 2005 and
expires on June 30, 2010. Current permitted effluent requirements pertaining to the secondary
treatment process are summarized in Table 1-2.
Table 1.2 — Current Effluent Quality Requirements
Flow, mgd
BOD5 (Apr. 1 — Oct. 31), mg/L
BOD5 (Nov. 1 — Mar. 31), mg/L
TSS, mg/L
NH3-N (Apr. 1 — Oct. 31), mglL
NH3-N (Nov. 1 — Mar. 31), mg/L
TP Load, lb/day
TP Concentration, mglL
1.3. Plant Performance Problems
12-Month Avg. Monthly Avg. Weekly Avg.
20.85
1.00
2.5
5.0 7.5
10 15
30 45
2.0 6.0
4.0 12.0
41.70
2.00
The Twelve Mile Creek WWTP has typically produced a high quality effluent with minimal
NPDES permit violations until January 2005. • In 2002, the plant had three notices of violations
(NOVs) issued for the facility from NCDENR. These included failure of two chronic toxicity tests
and a weekly fecal coliform violation related to high flows and secondary clarifier solids wash-
out resulting in blinding of the tertiary filters and high solids concentrations to the ultraviolet (UV)
disinfection facility. In August 2003, there were two NOVs: one for fecal coliform related to
power outage and one for weekly ammonia concentration apparently due to low dissolved
oxygen levels in the aeration basin. In 2004, the plant received three NOVs all related to a
Union County
Twelve Mile Creek wwTP
Perron nance Evaluation
4

PERFORMANCE EVALUATION Twelve Mile Creek WWTP
power failure and related equipment damage. Beginning in January 2005, the plant
performance degraded significantly and the Twelve Mille Creek WWTP received 45 NOVs for
the calendar year. Major electrical equipment failures combined with low influent temperatures
resulted in loss of nitrification and a major process upset that lasted into April 2005. A similar
loss of nitrification was experienced in December 2005. In early 2006, the plant experienced
additional power failures and low wastewater temperatures that resulted in violations.
Throughout 2005 and 2006, the Twelve Mile Creek WWTP has had difficulty in maintaining
consistent low effluent phosphorus concentrations and has violated both monthly average and
annual average total phosphorus concentration requirements. As a result, Union County
retained Hazen and Sawyer to perform a Phosphorus Optimization Study for the facility. This
study identified operational improvements as well as capital improvements required to ensure
that the plant meets the current total phosphorus limits as well as lower concentration limits
associated with the 6 mgd expansion of the Twelve Mile Creek WWTP.
2.0. Wastewater Characterization
Historical data from the past two years (January 2004 through December 2005) was used to
characterize the influent wastewater and develop annual average flows, concentrations and
Toads as well as maximum month peaking factors. Daily influent flow, temperature, total
suspended solids (TSS) and 5-day biochemical oxygen demand (BOD5) data were available.
TSS and BOD5 samples are collected and analyzed on weekdays only. In addition, influent
samples are analyzed weekly for ammonia (NH3-N), total nitrogen (TN) and total phosphorus
(TP). It is assumed, for the purposes of the wastewater characterization, that the influent
concentrations of nitrate (NO3) and nitrite (NO2) are insignificant and that the influent TN is
equivalent to the total Kjeldahl nitrogen (TKN) concentration.
A composite influent sampler collects influent samples over a twenty-four hour period based on
flow proportion. The influent sampler is located in the headworks just downstream of the
screens. Plant recycle flows including plant drains, filter backwash and digester decant are
returned to treatment upstream of the headworks. Therefore, the influence of these return
streams is accounted for in the influent samples.
Historical wastewater characteristics are summarized in Table 2-1. A more detailed analysis of
the influent wastewater characteristics is provided in Appendix A. Maximum month wastewater
characteristics, including the peak factor, are based upon a load analysis, discussed further in
Appendix A.
Table 2-1 — Historical Wastewater Characteristics
Annual Average Maximum Month Load Peak Factor
Flow, mgd 2.2 2.6 1.21
BOD, mg/L 237 274 1.40
TSS, mg/L 279 401 1.74
TN, mg/L 40.4 41.1 1.23
NH3-N, mg/L 25.5 24.9 1.18
TP, mg/L 7.6 9.8 1.56
Union County
Twelve Mile Creek WWTP
Performance Evaluation
5

PERFORMANCE EVALUATION Twelve Mile Creek WWTP
The current annual average daily flow is approximately 2.15 rngd (from June 2005 to May
2006). The peak maximum month flow has already exceeded the permitted capacity of the
Twelve Mile Creek WWTP. Maximum month load peaking factors for TSS and TP may be
skewed by the influence of the plant recycle streams. The average temperature during the two
years evaluated was 19.3°C, and the minimum and maximum month temperatures were 12.7°C
and 25.3°C, respectively*
3.0. Operations and Performance
Union County Twelve Mile Creek WWTP operational and performance data from the past two
years was evaluated to understand current operations and determine the treatment efficiency of
the existing process. Daily laboratory reports provided weekday mixed liquor suspended solids
(MLSS) concentrations, sludge volume indices (SVIs) and dissolved oxygen (DO)
concentrations in each of the two oxidation ditches. Monthly operating logs provided daily RAS
and waste activated sludge (WAS) flow rates as well as a record of decant operations, solids
hauling, operational upsets and equipment malfunctions. Historical plant effluent concentrations
are presented in Figures 3-1 through 3-3.
1000
mo
A
Figure 3-1 — Effluent BOD5 and TSS Concentrations
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BOD A TSS .-*--BOD - Monthly Avg. —1OTSS , Monthly Avg
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The most notable observation from the operational data was a major process upset that
occurred during the first part of 2005. An increase in effluent solids occurred from January until
May 2005, and nitrification was lost from the middle of January until April 2005. The process
upset can be attributed to a variety of factors including loss of electrical power to the WWTP,
Union County
Twelve Mile Creek WWTP
Performance Evaluation

PERFORMANCE EVALUATION Twelve Mile Creek WWT.P
filter blinding and maintenance issues, in particular, a power outage damaged the high speed
starters on the aerator motors, and the aerators were not able to deliver sufficient oxygen for
nitrification. The process has since recovered and effluent BOD5, TSB, NH3 and TN
concentrations returned to typical concentrations before the upset. An increase in these
concentrations was seen again in December 2005. This may also be attributed to a lack of
oxygen for effective nitrification, as flows and influent loads exceeded design conditions,
Excluding these occurrences, effluent TN concentrations are typically below 5 mg/L, indicating
efficient denitrification as well,
Figure 3-2 — Effluent Nitrogen Concentrations
40
25
20
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9 95
10
Union County
Twelve Mile Creek WWTP
Performance Evaluation
r
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♦ NH3-N • TN ^ TN - Monthly Avg.
7

PERFORMANCE EVALUATION Twelve Mile Creek WWTP
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Figure 3-3 — Effluent Total Phosphorus Concentrations
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Effluent total phosphorus concentrations increased in the last half of 2005. The average effluent
TP concentration during this period was approximately 3 mg/L, and Union County has exceeded
their permitted phosphorus load to Twelve Mile Creek. In contrast, the average effluent TP
concentration before the process upset was approximately 1.2 mg/L. The effluent TP
concentration reached a maximum in January 2005, which coincided with the beginning of the
process upset. Effluent TP was reduced to previous concentrations during the upset (from
February through May 2005). This may be attributed to alum being added at the onset of the
process upset and an increase in the effective anaerobic volume, which promotes biological
phosphorus reduction, due to the loss of nitrification and subsequent absence of nitrate in the
internal recycle and RAS return flows. Since nitrification has been restored since May and
denitrification is occurring in the anoxic zones, the available anaerobic volume has decreased,
reducing biological phosphorus removal. Alum addition has been discontinued since the
process has recovered.
The Twelve Mile Creek WWTP typically operates at a MLSS concentration between 4,000 and
5,500 mg/L. The average MLSS over the two year period evaluated was approximately 4,700
mg/L. Operations staff reports a typical volatile content (f„) of 75%.
Historical solids retention times (SRT) were also evaluated to determine the impact on the loss
of nitrification. The solids retention time was computed using only the volume in the oxidation
ditch. The volumes of the anaerobic and anoxic tanks were omitted. It should be noted that
solids are only wasted on weekdays, and even then solids are not wasted every day. This
results in variable MLSS concentrations and resulting SRTs. The average SRT during the
period evaluated was over 26 days,
Union County
Twelve Mile Creek WWTP
Performance Evaluation

I
PERFORMANCE EVALUATION Twelve Mile Creek WWTP
The historical sludge volume index (SVI) was also evaluated. The SVI dropped at the onset of
the process upset due to a reduction in bulking organisms through RAS chlorination. The RAS
was also chlorinated in December 2005, as evidenced by another decrease in SVI. Table 3-1
presents the historical 50, 90 and 99-percentile SVI values.
Table 3-1 - SVI Percentile Values
SVI (mL/g)
50th-percentile 166
90th-percentile 204
99th-percentile 243
Dissolved oxygen concentrations are monitored between the aerator and effluent weir. The
average DO concentrations in Oxidation Ditch No. 1 and Oxidation Ditch No. 2 were 2.0 mg/L
and 1.8 mg/L, respectively. With the exception of Spring 2004 and January 2006, the DO
concentrations in each basin followed a similar trend, with slightly greater DO concentrations in
Oxidation Ditch No. 1. Plots of the plant operational data are attached as Appendix B.
4.0. Process Modeling and Evaluation
Computer modeling of the biological system using BioWin software was used in order to assess
the capacity of the existing oxidation ditches and identify potential operational and/or capital
improvements that will enable the Twelve Mile Creek WWTP to reliably meet total phosphorus
and other effluent requirements. BioWin is a dynamic wastewater treatment process modeling
and simulation software package widely utilized for process design and optimization. A model
of the Twelve Mile Creek WWTP was developed in BioWin and calibrated based upon historical
data and the results of a supplemental sampling program. The calibrated BioWin model
predicted effluent nitrogen concentrations fairly accurately. Actual effluent phosphorus
concentrations were lower than those predicted by the model. The dynamic model predicted
MLSS and MLVSS concentrations of approximately 3,400 mgfL and 2,500 mg/L respectively.
This correlated well to the solids concentrations found during the secondary effluent special
sampling.
4.1. Process Evaluation
The calibrated model was used to evaluate various treatment scenarios to determine treatment
process deficiencies and to optimize biological phosphorus removal. The evaluation assumes
that the flow distribution issue apparent during the supplemental sampling period will be
corrected and that sufficient aeration will be provided to the oxidation ditch. The process
evaluation identified several issues for which investigations should be made as follows:
• Plant Recycle Streams
• Nitrified Recycle Rate
• Dissolved Oxygen Return
• Readily Biodegradable Carbon
Union County
Twelve Mile Creek WWTP
Performance Evaluation
9

PERFORMANCE EVALUATION Twelve Mile Creek WWTP
• Secondary Clarifier Blanket Level
• SRT Analysis and Optimization
• Chemical Phosphorus Precipitation
The process evaluation was based on maximum month Toad conditions. Table 4-1 summarizes
the maximum month influent concentrations used in the modeling and analysis. The maximum
month TSS concentration was reduced from the historical concentration presented previously to
a more realistic value since reported peak TSS concentrations are likely overstated due to the
proximity of the influent sampler to the recycle stream return. Process options were evaluated
at an SRT of twelve days and the minimum month temperature of 12°C.
Table 4-1 — Maximum Month Conditions
Constituent Maximum Month
Flow, mgd 2.5
BOD5, mg/L 274
TSS, mg/L 288
TKN, mg/L 41
NH3-N, mg/L 27
TP, mg/L 9.8
PO4-P, mg/L 5.9
4.1.1. Plant Recycle Streams
Filter backwash, plant drain flows and aerobic digester decent or rotary drum thickener centrate
flow by gravity to the in -plant pump station, which pumps the flow back to the headworks. The
digester decant is a significant source of phosphorus and other loads to the secondary process.
Decant total phosphorus concentrations up to 85 mg/L were measured during the supplemental
sampling period, and operations staff report historical decant total phosphorus concentrations
between 130 and 180 mg/L. The remaining recycle flows likely do not contribute much to the
phosphorus loading of the process.
The digesters are decanted several times a month for a period of two to three days at a time.
There is no direct flow measurement of the decant flow, but operations estimates the flow to be
approximately 80,000 gpd and a typical total flow of 180,000 gallons over the decant period.
The digesters are decanted to thicken the sludge, which is hauled off -site quarterly for land
application.
The process model was used to determine the effect of removing the digester decant return
flow. Predicted total phosphorus effluent concentrations decreased from 0.81 mg/L to 0.53
mg/L and orthophosphate loads were reduced from 0.65 mg/L to 0.41 mg/L. In addition,
removing the digester decant return flow significantly reduces the variability of the phosphorus
and other waste Toads to the secondary process, which may substantially increase the reliability
of the process. Reducing or eliminating the digester decant flow will also reduce the inert solids
loading to the process, reducing MLSS concentrations.
Union County
Twelve Mile Creek WWTP
Performance Evaluation
10

PERFORMANCE EVALUATION Twelve Mile Creek WWTP
The process model was also used to simulate introducing the recycle flow directly to the aerobic
portion of the oxidation ditch. The model predicted no significant change in effluent phosphorus
concentrations in comparison to current operations.
4.1.2. Nitrified Recycle Rate
Nitrate is returned from the oxidation ditch to the anoxic zone through an adjustable gate prior to
the oxidation ditch aerator zone. The nitrified recycle rate can range from 3 to 15 times the
influent flow rate, depending on the position of the gate. The gate may also be fully shut to
avoid recycle of nitrate to the anoxic zone. If the gate is fully shut, the anoxic zone acts as
additional anaerobic volume.
The internal recycle gates were fully open at both ditches during the supplemental sampling
period. Based on a mass balance of ammonia around the anoxic zone, it was estimated that
each oxidation ditch was recycling approximately 715% of the influent flow for a total nitrified
recycle rate of 1430%. This is consistent with the manufacturers stated maximum internal
recycle rate of 1500%.
The effects of reducing the nitrified recycle rate and shutting the gates completely to avoid
nitrified return were evaluated using the process model. Effluent nitrate and total nitrogen
concentrations were evaluated in addition to phosphorus removal.
Phosphorus removal increased with a reduction in the nitrified recycle rate. Effluent nitrate and
total nitrogen concentrations increased with a decreased nitrified recycle rate. Increasing the
recycle rates above 400% had little effect on effluent nitrogen and phosphorus concentrations.
The model estimated that an additional 0.15 mg/L of phosphorus could be removed by shutting
the gates.
Although additional biological phosphorus removal may occur if the nitrified recycle gate is
adjusted to reduce or prevent denitrification, it is not recommended since it may cause
operational issues, including pH depression due to reduced alkalinity recovery via denitrification.
A decrease in pH would inhibit nitrification. The process modeling indicated a pH depression of
0.4 units when the gate was fully closed compared to allowing 400% nitrified recycle. Oxygen
requirements would also increase if denitrification was prevented. The nitrified recycle gate
should be set to allow a minimum of 400% of the influent flow to be recycled back to the anoxic
zone.
4.1.3. Dissolved Oxygen Return
In order to optimize biological phosphorus removal, introduction of dissolved oxygen to the
anaerobic zone must be avoided. In some facilities, RAS can contribute significant dissolved
oxygen to the anaerobic zone, inhibiting biological phosphorus removal. RAS deoxygenation
zones can be .implemented to strip oxygen from the RAS to improve biological phosphorus
removal.
The dissolved oxygen profiles performed during the supplemental sampling week indicated that
there was no significant dissolved oxygen in the anaerobic zone. In addition, the high
secondary sludge blankets reported indicate that the RAS is likely anoxic. Therefore, it is
Union County
Twelve Mile Creek WWTP
Performance Evaluation
11

PERFORMANCE EVALUATION Twelve Mile Creek WWTP
unlikely the RAS is returning significant dissolved oxygen to the anaerobic zone. Incorporation
of a RAS dissolved oxygen stripping zone will have little effect on biological phosphorus
treatment under current conditions at the Twelve Mile Creek WWTP,
4.1.4. Readily Biodegradable Carbon
Readily biodegradable carbon is required for biological phosphorus removal. The influent BOD
to TP ratio (BOD:TP) is often used as an indicator of biological phosphorus potential. In
general, an influent BOD:TP ratio of at least 25:1 is considered favorable for biological
phosphorus removal. However, a recent Water Environment Research Foundation (WERE)
study indicates that variability in the BOD:TP ratio has a greater effect on effluent phosphorus
concentrations than absolute BOD:TP ratios (Neethling, et. al, ES-9). Effluent phosphorus was
observed to increase on occasions where the BOD:TP ratio decreased. It was hypothesized
that changes in the steady state operation of the phosphorus accumulating organisms (PAOs)
associated with the variable BOD:TP ratio resulted in excessive release of accumulated
phosphorus in the biomass.
The Twelve Mile Creek WWTP has a historical average BOD:TP ratio of approximately 33,
which is typically indicative of a system that can achieve reliable biological phosphorus removal.
Ninety percent of the influent samples that were analyzed for both BOD and TP had ratios
above 25. The historical data was further evaluated (Figure 4-1) to determine if there was a
correlation between influent BOD:TP ratio and effluent total phosphorus concentration.
Figure 4-1 — Effluent TP vs. Influent BOD:TP
GO
O 45
i9
rt 40
a.
g 35
E 30
c
25
10
Union County
Twelve Mile Creek WWTP
Performance Evaluation
'▪ YI
Z
InFluenl BO P
•
a
TP
a
13
12
11
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PERFORMANCE EVALUATION Twelve Mile Creek WWTP
The variability of the BOD:TP ratio appeared to influence the effluent phosphorus concentration
on several occasions. An increase in the BOD:TP ratio in Spring 2005 correlated to a decrease
in effluent TP concentration, and effluent TP concentrations increased when the influent ratio
decreased in the second half of the year. Similarly, effluent TP concentrations decreased in
January 2006, corresponding to an increase in BOD:TP. A decrease in the BOD:TP ratio in
February correlates to an increase in effluent TP concentration as well.
Typical influent BOD:TP ratios at the Twelve Mile Creek WWTP would tend to support reliable
biological phosphorus removal. It is uncertain whether variability in the influent BOD:TP ratio
may be partly responsible for inconsistent effluent TP concentrations. However, recent
research indicates that variable ratios may lessen reliability of biological phosphorus removal.
Variability in this influent ratio at the Twelve Mile Creek WWTP may be reduced by removing the
reintroduction of solids recycle streams (decant) to the process. This would also have the
added benefit of increasing the BOD:TP ratio, since the recycle streams contain high amounts
of phosphorus but limited readily biodegradable carbon (the recycle stream BOD:TP ratio was
found to be —11:1 during the supplemental sampling period).
4.1.5. Secondary Clarifier Blanket Level
Phosphate accumulated in the biomass may be released during anaerobic/anoxic conditions.
These conditions may occur during secondary clarification, particularly if high sludge blankets
and low dissolved oxygen concentrations in the clarifiers are present. High secondary clarifier
blanket levels are reported to be common at the Twelve Mile Creek WWTP. Operational data
indicates that blankets can exceed 10 feet at times. Furthermore, blanket levels in the two
clarifiers can be significantly different at the same time. Operations staff reports that it is very
difficult to evenly withdraw sludge from the two clarifiers. Sludge currently flows by gravity to a
common wetweli, where it is pumped back to the head of the plant. Provisions for isolating the
wetwell such that separate RAS pumps are used to control blanket depths in each clarifier are
being incorporated into the current construction of the expansion. High flow events have
resulted in loss of secondary clarifier sludge blankets to the downstream effluent filter facilities.
This failure mode has been responsible for the majority of the BOD, TSS, ammonia,
phosphorus, and fecal coliform violations at the Twelve Mile Creek WWTP.
The nutrient profile performed on January 25, 2006 indicated a release of phosphate in the
secondary clarifier. The secondary effluent ortho-phosphate concentration was 0.45 mg/L,
whereas aeration basin effluent concentrations were less than 0.10 mg/L. However, secondary
release was not apparent on the first day of nutrient profiling (January 24th). Sludge blankets
recorded for these two days were not significantly different. However, diurnal variations in
sludge blanket may attribute to the observation of phosphate release on only one day.
Release of phosphate in the secondary clarifiers appears to occur at times. High sludge
blankets and low oxidation ditch effluent dissolved oxygen create favorable conditions for
phosphorus release at the Twelve Mile Creek WWTP. Phosphorus release can be reduced by
maintaining low sludge blanket levels, if possible, and ensuring the mixed liquor exiting the
oxidation ditches is sufficiently aerated prior to introduction in the clarifier. Providing aeration in
lieu of mechanical mixing at the mixed liquor splitter box, currently under construction, may
reduce the potential of phosphate release at the clarifiers. Maintaining lower sludge blankets
Union County
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13

PERFORMANCE EVALUATION Twelve Mile Creek WWTP
will also optimize total phosphorus removal by reducing the amount of solids loss over the
clarifier weirs.
4.1.6. SRT Analysis and Optimization
The solids retention time (SRT) can significantly affect biological phosphorus removal.
Increased solids retention times decrease the efficiency of biological phosphorus removal due to
cell decay and resulting phosphorus release experienced at long sludge ages. However, it is
important to maintain the minimum aerobic SRT required for nitrification to meet effluent
ammonia limitations, Therefore, the aerobic SRT should be optimized for biological phosphorus
removal and ammonia removal,
The process model was used to evaluate biological phosphorus removal over a range of SRTs
for various temperatures. The SRT was calculated using only the volume of the oxidation ditch
(anaerobic and anoxic zones were omitted), to provide an aerobic SRT. This evaluation was
based upon maintaining aerobic conditions throughout the oxidation ditch. Figure 4-2 presents
the results of the SRT analysis,
Figure 4-2 — Effluent Phosphate vs. SRT
0,9
0 A
-4 0
-47
2
t 0.5
LU
0 4
4 5
35
2 )
0
E
0.6
0 3 - 0
6 7
a 9 10 11 12 13 14 15 16
Oxidation Ditch SRT idays)
* ' P 0 4 4 12C PO4 (0 19C —0--PO4 g,.., 26C .1 * Nt1.3 @ 12C —di —NH3 © 19C --411—NR3 @... 213C
As expected, the model indicated better phosphorus removal at lower SRTs. However,
particularly under cold weather conditions, the aerobic SRT has a significant effect on ammonia
removal. in order to assure that cold weather ammonia effluent limits are met (2,0 mg/L
maximum month average at the 6.0 mgd design condition), a minimum aerobic SRT of 12 days
should be maintained during the winter. The aerobic SRT can be reduced to 6 days during the
Union County
Twelve Mile Creek WWTP
Performance Evaluation
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PERFORMANCE EVALUATION Twelve Mile Creek WWTP
summer to optimize biological phosphorus removal while still meeting the 1.0 mg/L effluent
ammonia limit. An 8 day aerobic SRT is recommended during the remainder of the year to
optimize biological phosphorus removal and maintain nitrification. Minimizing the SRT will
increase the wasting requirements at the Twelve Mile Creek WWTP.
4.1.7. Chemical Phosphorus Removal
The process modeling indicated that SRT control could produce effluent soluble phosphate
concentrations between 0.5 mg/L to 0.6 mg/L. This is adequate to provide an effluent total
phosphorus concentration less than 1.0 mg/L provided that solids are removed below 10 mg/L
TSS. However, chemical phosphorus removal can be used to further reduce effluent soluble
phosphate concentrations. The Twelve Mile Creek WWTP has existing alum facilities, and has
used them in the past for phosphorus removal.
Process modeling indicated that an alum feed rate of 150 gallons per day at 2.5 mgd would
reduce soluble phosphate concentrations below 0.05 mg/L and total phosphorus concentrations
below 0.25, based on an effluent TSS of 5 mg/L. The predicted alum feed rate is based upon
providing 300% of the stoichiometric alum requirement to precipitate phosphorus. Jar testing is
recommended to better quantify the required feed rate.
5.0. Optimization of Existing Facilities
The Twelve Mile Creek WWTP has facilities in place to provide biological nitrogen and
phosphorus removal. However, increasing/variable flows and loads, operational issues and
deficiencies in the plant infrastructure have prevented the facility from being able to reliably
meet permitted effluent phosphorus requirements. The existing processes at the plant were
evaluated with respect to permit compliance with an emphasis upon optimization for
phosphorous removal. Several operational changes can be made in order to optimize biological
phosphorus removal at the Twelve Mile Creek WWTP and allow reliable NPDES permit
compliance. The recommended process modifications include:
• Reduce Digester Decant Recycle
• SRT Optimization
• Reliable Solids Removal
• Chemical Phosphorus Trim
5.1. Reduce Digester Decant Recycle
The results of the supplemental sampling program indicate that the recycle of phosphorus from
the aerobic digesters can increase the phosphorus loading to the process by 50% to 100%.
Dynamic simulations of historical operating data indicate the potential for elevated effluent
phosphorus concentrations due to the increased loads during and after decant operations. It is
recommended that the influence of decant from the digesters be reduced in order to consistently
reduce total phosphorus concentrations below permitted effluent limits.
Cell lysis and decay, resulting in release of stored phosphorus, occurs due to the prolonged
solids retention times (- 90 days) in the digesters. The impact of the recycle stream could be
diminished by reducing the solids retention time in the digesters. Increased solids hauling
frequency is required in order to decrease the retention time in the digester. Reducing the need
Union County
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15

PERFORMANCE EVALUATION Twelve Mile Creek WWTP
for decanting from the digesters would also be beneficial to provide reliable biological
phosphorus removal.
It is recommended that the existing rotary drum thickener be utilized to reduce the reliance on
decanting operations to thicken waste activated sludge. Plant staff has indicated that they have
had problems aerating thickened sludge. Thickened and un-thickened sludge could be blended
to achieve the desired solids percentage. Reducing digester decant operations will reduce the
quantity and variability of phosphorus loads and improve biological phosphorus process
reliability.
5.2. SRT Optimization
Optimizing the solids retention time is recommended to promote biological phosphorus removal
while maintaining nitrification. The SRT should be limited to the minimum required for full
nitrification. A minimum aerobic SRT of 12 days should be maintained during the winter to
ensure full nitrification. The aerobic SRT can be lowered to 6 days during the summer to
maximize biological phosphorus removal. Minimizing the SRT has the added benefit of
reducing the operational MLSS, which will reduce the solids loading to the secondary clarifiers
and increase clarifier reliability. Maximum month operational MLSS concentrations at the
reduced SRTs are predicted to be 2,000 mg/L in the summer to 3,500 mg/L in winter. These
concentrations do not include any additional solids Toad attributed to the use of alum for
chemical phosphorus removal.
Additional solids wasting will be required in order to minimize the SRT. It is estimated that
between 5,000 and 5,200 lbslday of solids will need to be wasted from the secondary process at
the design flow of 2.5 mgd. This is approximately 25% greater than the design solids production
rate of approximately 4,000 lbslday. It is recommended that solids be continually wasted to
maintain the target SRT and improve process reliability. Recommended solids retention times
and resulting MLSS concentrations and wasting rates are summarized in Table 5-1.
Table 5-1 — Recommended SRT Optimization
Parameter T < 14°C 14°C < T < 19°C T > 19°C
Aerobic SRT, days 12 8 6
MLSS, mg/L 3,500 2,700 2,000
Solids Prod., Ibs/day 5,000 5,100 5,200
WAS Flow, mgd 0.09 0.13 0.18
WAS Flow, gpm 62 90 125
5.3. Reliable Solids Removal
The historical operating data indicates frequent Toss of solids through the secondary clarifiers
and blinding of the effluent filters. in addition to exceeding permitted TSS and CBOD
concentrations, total phosphorus limits are being exceeded due to particulate phosphorus.
Consistent solids settling and removal are imperative in providing reliable phosphorus removal.
The solids settling tests conducted during supplemental sampling indicate a well settling sludge.
in addition, current solids and hydraulic loading rates are within acceptable guidelines. Plant
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Twelve Mile Creek WWTP
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PERFORMANCE EVALUATION Twelve Mile Creek WWTP
operations staff has had problems with uneven sludge withdrawal from the existing clarifiers.
The clarifiers operate at high mixed liquor concentrations, averaging 4,700 mg/L with maximum
reported concentrations above 6,000 mg/L. Limiting the operational solids retention time will
reduce the mixed liquor concentrations to the clarifiers. It is also recommended that the Twelve
Mile Creek WWTP be proactive in chlorinating RAS as SVI values increase to reduce the impact
of filamentous bacteria on settling.
The effluent filters provide an additional solids barrier prior to effluent disinfection and disposal.
However, these filters become blinded when secondary effluent solids concentrations increase.
Therefore, it is necessary that the secondary clarifiers are operated to achieve maximum solids
removal prior to the filters.
5.4. Chemical Phosphorus Precipitation
Alum feed facilities are currently in place at the Twelve Mile Creek WWTP. Alum has been fed
at times to reduce effluent phosphorus, but is not currently being applied. It is recommended.
that alum be fed upstream of the secondary clarifier to ensure total phosphorus limits are met.
Alum feed should be coordinated with effluent phosphorus monitoring to avoid overfeed of alum,
which increases operational costs and may inhibit biological phosphorus (as well as BOD and
nitrogen) uptake by decreasing the availability of phosphate for biomass growth.
Operations can be further improved by providing chemical phosphorus precipitation for the plant
recycle streams (decanting). Facilities are not currently in place to allow alum dosing of the
plant recycle streams.
5.5. Solids Handling Optimization
Optimization of solids handling operations is required in order to reduce digester decant recycle
while limiting process SRTs to promote biological phosphorus removal. Operation of the
existing rotary drum thickener (RDT) is preferable to thickening via decanting the digesters. It is
recommended that a portion of the WAS be diverted to the RDT, where it can be thickened and
recombined with unthickened WAS in Digester No. 2, from which the combined solids are
pumped to Digester No.3 where they are stored prior to hauling for land application.
The existing RDT has a hydraulic capacity of 200 gpm and can produce a thickened waste
activated sludge (TWAS) containing 6% solids. Annual land application reports indicate that the
average solids concentration hauled from the Twelve Mile Creek WWTP from 2003 through
2005 was 2.3%. The ability of the existing RDT to thicken sufficient WAS to produce solids
concentrations of 2%, 3% and 4% in Digester No. 3 was evaluated. VSS destruction was
assumed to be 38%. Predicted thickener run times for five and seven day per week operation
are summarized in Table 5-2 and Table 5-3, respectively.
Table 5-2 — RDT Operation — 2,5 MGD Design Flow — 5 Days per Week
SRT 2% Solids, hrs 3% Solids, hrs 4% Solids, hrs
6 Days 9.0 14.2 19.5
8 Days 6.3 10.2 14.0
10 Days 5.2 8.5 11.9
12 Days 4.2 6.9 91
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PERFORMANCE EVALUATION Twelve Mile Creek WWTP
Table 5-3 — RDT Operation — 2.5 MGD Design Flow — 7 Days per Week
SRT
6 Days
8 Days
10 Days
12 Days
2% Solids, hrs
6.4
4.5
3.7
3.0
3% Solids, hrs
10.2
7.3
6.1
4.9
4% Solids, hrs
13.9
10.0
8.5
6.9
Digester capacity was also evaluated to ensure adequate detention time for solids stabilization
and capacity for solids storage. As in the above analysis, 38% VSS destruction was assumed,
as well as elimination of digester decanting operations. Table 5-4 summarizes the digester
capacity, in days, for a range of solids concentrations for the 2.5 mgd design flow. The volumes
of Digesters No.1 and No. 2 are not included in the capacity calculation, but would increase the
detention time for solids stabilization and solids storage.
Table 5-4 — Digester Capacity
Solids Conc.
2% Solids
3% Solids
4% Solids
2.5 mgd Design Flow
49 days
73 days
98 days
Sufficient digester capacity currently exists to provide in excess of 90 days of solids storage at a
solids concentration of 4% at the current design flow. Additional digester capacity is not
considered necessary provided solids can be reliably hauled from the Twelve Mile Creek
WWTP.
6.0. Required Capital Improvements
Several operational changes are recommended to improve treatment performance for the
Twelve Mile Creek WWTP, however, it is anticipated that the plant will not perform reliably
without capital improvements. The recommended capital improvements include:
• Stand-by Power Facilities
• Additional Aeration Capacity
• Secondary Clarifier Flow Distribution and Solids Removal
6.1. Stand-by Power
The existing WWTP only provides stand-by power facilities for the influent pump station and not
for the aeration equipment or for the UV disinfection equipment. Stand-by power generators are
recommended to allow continued operation when the electric utility is unable to supply power.
This equipment is critical to the continued operation of the plant as demonstrated by the
numerous power outages and associated permit violations that have occurred in the past two
years. Stand-by generators are planned. as part of the 6 mgd plant expansion currently under
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1
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PERFORMANCE EVALUATION Twelve Mile Creek WWTP
construction. A new 1000 kw generator will be provided at the influent pump station and a 800
kw generator will be provided to serve the main plant equipment including the aeration
equipment and UV disinfection equipment.
6.2. Supplemental Aeration
The existing mechanical surface aerators in the existing oxidation ditches do not have sufficient
aeration capacity to provide reliable treatment. Nitrification is commonly lost, even at extended
solids retention times. Biological phosphorus removal depends on luxury phosphorus uptake
under aerobic conditions. The historical data and supplemental sampling indicate that
significant portions of the oxidation ditch are likely operating more in an anoxic mode,
decreasing the aerobic volume which may lead to a reduction in luxury phosphorus uptake. The
additional anoxic volume may also promote re-release of phosphate, further reducing biological
phosphorus removal.
Additional aeration is required in order to provide adequate aerobic volume for complete
nitrification, and may also benefit biological phosphorus removal by promoting luxury
phosphorus uptake. Because the existing oxidation ditches can not be removed from service
without the risk of more serious non-compliance issues, it is recommended that the existing
aerators be supplemented with additional aeration equipment. Union County is currently
pursuing the installation of floating aeration equipment in the oxidation ditches as a temporary
measure to provide adequate aeration while the expansion to 6.0 mgd facilities are constructed.
The size of the aerators for the new oxidation ditches currently under construction is also
planned to be increased to provide sufficient aeration under all operating conditions.
6.3. Secondary Clarifier Flow Distribution and Solids Removal
The frequent loss of solids through the secondary clarifiers has resulted in blinding of the
effluent filters which as been the cause of permit violations for BOD, TSS, ammonia and total
phosphorus. Several of the fecal coliform violations have also been traced to this issue. The
current secondary clarifier flow distribution arrangement is extremely difficult to control to
provide consistent flow distribution. The return activated sludge (RAS) piping is to a common
RAS pumping system that is difficult to almost impossible to control such that individual clarifier
sludge blanket levels are maintained.
An MLSS distribution structure and modifications to the RAS pumping system are
recommended and will be included in the construction of the expansion to 6.0 mgd. These
features should greatly increase secondary clarifier reliability. Individual submersible RAS
pumps are being provided for each clarifier, which will help provide more even sludge
withdrawal.
6.4. Optimization of Rotary Drum Thickener
It is recommended as part of the optimization of existing facilities that the existing rotary drum
thickening equipment be utilized to thicken waste activated sludge before digestion such that
the need for post -digestion thickening through decanting is minimized. It is anticipated that
operation of the rotary drum thickener would not totally eliminate the practice of decanting the
digester prior to biosolids disposal, but would greatly reduce it.
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PERFORMANCE EVALUATION Twelve Mile Creek WWTP
7.0. Anticipated Performance in Interim Period
The Twelve Mile Creek WWTP has had recent problems with non-compliance with several
parameters of the NPDES permit. Increasing/variable flows and loads, operational issues, and
deficiencies in the plant infrastructure have prevented the facility from being able to reliably
meet permitted effluent BOD, TSS, ammonia, and total phosphorus requirements. It is
anticipated that these difficulties will continue until the recommended improvements are
completed. An analysis of the plant performance was conducted and it is recommended that
the Twelve Mile Creek WWTP can not reliably meet current NPDES permit limits until the
recommended improvements are completed. Anticipated reliable performance until the
improvements are made is as follows:
Effluent Characteristics
Monthly Average
Weekly Average
Flow, mgd
3
---
BOD5 (Apri11 — October 31), mg/L
12.0
18.0
BOD5 (November 1 — March 31), mg/L
12.0
18.0
Total Suspended Solids, mg/L
30
45
NH3-N (April 1 — October 31), mg/L
6.0
12.0
NH3-N (November 1 — March 31), mg/L
6.0
12.0
Total Phosphorus, lb/day
60.00
Delete "Annual
Average" Permit
Requirement of
20.85 lb/day
Fecal Coliform
(geometric mean)
200 CFU/100 mi
Delete "Daily
Maximum" Permit
Requirement of
400 CFUI100 ml
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Twelve Mile Creek WWTP
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20

PERFORMANCE EVALUATION Twelve Mile Creek WWTP
Appendix A
Flow and Load Analysis
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Twelve Mile Creek WWTP
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21

PERFORMANCE EVALUATION Twelve Mile Creek WWTP
Historical data from the past two years (January 2004 through December 2005) was used to
characterize the influent wastewater and develop annual average flows, concentrations and
Toads as well as peaking factors. Daily influent flow, temperature, total suspended solids (TSS)
and 5-day biochemical oxygen demand (BOD5) data were available. TSS and BOD5 samples
are collected and analyzed on weekdays only. In addition, influent samples are analyzed
weekly for ammonia (NH3-N), total nitrogen (TN) and total phosphorus (TP). It is assumed, for
the purposes of the wastewater characterization, that the influent concentrations of nitrate (NO3)
and nitrite (NO2) are insignificant and that the influent TN is equivalent to the total Kjeldahl
nitrogen (TKN) concentration.
A composite influent sampler collects influent samples over a twenty-four hour period based on
flow proportion. The influent sampler is located in the headworks just downstream of the
screens. Plant recycle flows including plant drains, filter backwash and digester decant are
returned to treatment upstream of the headworks. Therefore, the influence of these return
streams is accounted for in the influent samples.
The recycle streams have had a significant effect on the influent concentrations reported. TSS
and BOD5 concentrations above 1,000 mg/L have been reported throughout the historical period
analyzed. A closer evaluation of the data shows that these periods of high influent
concentrations often coincide with reported process upsets and equipment repair and
maintenance periods. Examples of these events, which are included on the daily operations
log, include filter blinding, draining of a clarifier for maintenance and returning activated sludge
through the plant drain system during return activated sludge (RAS) pump repair periods. Plant
influent data during these occurrences, including a significant portion of the data from April and
May 2005, were removed from the data set during initial screening of the data.
Historical daily influent flows are presented in Figure A-1. The annual average flow for the 2
year period was 2.0 mgd. The current annual average daily flow is approximately 2.15 mgd.
Historical flows and peaking factors for the two year period analyzed are summarized in Table
A-1.
Table A 1 - Historical Flows and Peaking Factors
Criteria Flow (MGD) Peaking Factor
Minimum Day
Average Annual
Maximum 30-Day
Maximum 7-Day
Maximum Day
1.1
2.0
2.6
3.0
4.9
0.56
1.00
1.21
1.40
2.22
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22

PERFORMANCE EVA
UAT
ON Twelve Mile Creek W'TP
4
Figure A-1 — Historical Influent Flows
Day Running Avg, *"30-Day Runn Avg.
Annual average influent BOD5, TSS, NH3, TN and TP concentrations were calculated.
Concentrations outside of two standard deviations were not included in the annual average
calculation to eliminate the influence of sampling, analytical or other errors that may skew the
average. The annual average concentrations are summarized in Table A-2, Resulting average
influent ratios are provided in Table A-3. Ratios are typical for domestic wastewater and are
favorable for biological nutrient removal.
Table Awl - Annual Average Influent Concentrations
Criteria Concentration
BOD, mg/L 237
TSS, mg/L 279
TN, mg/L 40.4
NH3-N, mg/L 25.5
TP, mg/L 7.6
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PERFORMANCE EVALUATION Twelve Mile Creek WWTP
Table A-3 — Average Influent Ratios
Ratio Value
Influent BODITN
Influent BODINH3
Influent BODITP
6.22
9.55
33.3
An influent load analysis of the historical data was used to determine influent load peaking
factors. Historical influent concentrations were converted to loads by multiplying the
concentration by the daily flow by a unit conversion factor. The following equation is used to
determine the loads in pounds per day (Iblday) from flow and concentration data.
Load (lb / day) = Q(mgd) * C(mg / L) * 8.34
Minimum month, maximum month, maximum week and maximum day Toad peaking factors
were developed and are presented in Table A-4. Maximum week NH3, TN and TP were not
computed since only one sample is taken weekly. Concentrations outside of three standard
deviations were omitted to avoid the influence of sampling and analytical errors.
Table A-4 - Historical Load Peaking Factors
Criteria BOD5 TSS TN NH3 TP
Minimum Day 0.29 0.20 0.50 0.60 0.51
Average Annual 1.00 1.00 1.00 1.00 1.00
Maximum 30-Day 1.40 1.74 1.23 1.18 1.56
Maximum 7-Day 1.79 2.29 NA NA NA
Maximum Day 3.55 3.03 1.61 1.31 2.22
The load peaking factors are typical of a municipal wastewater with the exception of maximum
day BOD5 and TSS loads, which are greater than typically encountered. This is likely due to the
influence of plant recycle streams (filter backwash and digester decant) being introduced
upstream of the sampling point. Plots of historical influent concentrations are given in Figures
A-2 through A-6.
union County
Twelve Mile Creek WWTP
Performance Evaluation
24

PERFORMANCE EVALUATION T weave lade Creek W%VTP
Figure A-2 — Influent BOD5 Concentration
Figure A-3 Influent TSB Concentration
o4-._..,_...-....._...,..8...
Z
7-Day Running Avg
0-Day Run Average "s
Union County
Twehre Mile Creek WWTP
Performance Evaluation
41
25

PE ORMANCE EVALUATION
Twelve le Creep
Figure A-4 - influent Ammonia Concentration
Figure A-5 - nfltient Tote Nitrogen Concentration
Union County
Twelve Mile Creek r�
Performance Evalu on
2

PERFOR A 'ALAITATION TwelveMile Creek "T '
Figure A-6 - Influent Total Phosphorus Concentration
Daily wastewater temperatures (effluent data obtained from daily monitoring reports) were also
evaluated for the two year period, Table -5 summarizes the temperature data, and Figure
presents a plot of the temperature trend over the past two years.
Table A-5Historical Effluent Temperatures
Criteria Temperature,
$nimum Day i i.9
nirnum 7-Day 12,5
Unrmum Month 1 .7'
Average Annual 19.3
Maximum 80_Day 25.3
Maximum 7-Day 25.8
Union County
Twelve ale Creek WIMP
Performance Evaluation
2

PERFOR
ANCE EVAUATION
Twel
ve 1
e Creek W TP
Figure A f — aster
Union County
Twelve Mile Creek
Performance Evaluation
ate
E uent Temperatures
Day Running Avg,
28

PERFORMANCE EVALUATION Twelve Mile Creek WWTP
Appendix B
Plant Operational Data
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Twelve Mile Creek WWTP
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PERFORMANCE EVALUATION
Twelve Mile Creek WWTP
•
Union County
Twelve Mile Creek WWTP
Performance Evaluation
Figure B-1 Historical MLSS Concentrations
♦
♦
♦
♦
17-111--Monthily,Avg.
Figure B-2 — Historical Solids Retention Times
7-day Running Avg. 30 y R unnang Avg.
•
30

PERFORMANCE EVALUATION
Twelve Mile Creek %WTP
Figure B-3 - Historical SVI
'' Monthly Avy,
Figure B-4 - Historical Oxidation Ditch Dissolved Oxygen
E
• • •a
4 R
C •
v • a
♦ • ♦
Union County
Twelve Mile Creek W1NTP
Performance Evaluation
31

of 1NA l-R
off/ QG
�r
Michael F. Easley, Governor
William G. Ross Jr., Secretary
North Carolina Department of Environment and Natural Resources
Alau W. Klimek, P.E. Director
Division of Water Quality
November 30, 2004
MEMORANDUM
TO: • Rex GIeason, Surface Water Protection Supervisor
Andrew Pitner, Aquifer Protection Supervisor
Mooresville Regional Office
FROM: gC`' Rob Brown, Project Manager
Facilities Evaluation Unit
Construction Grants and Loans Section
SUBJECT: County of Union
Twelve Mile Creek WWTP 201 Facilities Plan
Project No. CS370370-09
One copy of the subject 201 Plan is attached for the Mooresville Regional Office's technical
review and comment. The Regional Office's technical input concerning this project, based on
the Region's knowledge of Union County's Twelve Mile Creek treatment facilities needs, will be
greatly appreciated. Please keep this copy of the report for your files and return your comments
to this office by January 10, 2005, if possible.
Thank you for your continued cooperation and responsiveness. If you have any questions, please
contact me at [phone] at your earliest convenience.
Attachment
RB:dr
cc: Dan Blaisdell, P.E.
FEU/SRF
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DEC 0 2 200A
TTTION
Construction Grants and Loans Section
1633 Mail Service Center Raleigh NC 27699-1633
Phone: [phone] / FAX: [phone] / Internet: www,nccgLnet
An Equal Opportunity/Affirmative Action Employer— 50% Recycled/10°k Post Consumer Paper
NorthCarolina
1VatiiraIIry

RECEIVED
-, NOV 30 2004
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CONSTRUCTION
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201 Facilities Plan Amendment
Twelve Mile Creek
Wastewater Treatment Plant Expansion
Union County Public Works Department
400 North Church Street
Monroe, NC 28112
September, 2004
Revision 1 - November, 2004
niZipfa ¢
Prepared by:
McKim & Creed, PA
8020 Tower Point Drive
Charlotte, NC 28227

Table of Contents
SECTION PAGE
1.0 - EXECUTIVE SUMMARY 4
2.0 - CURRENT SITUATION 7
3.0 - WASTEWATER DISPOSAL ALTERNATIVES 17
4.0 - EVALUATION OF ALTERNATIVES 21
5.0-USER CHARGES AND FINANCIAL CAPABILITY 28
6.0 -- PROGRAM IMPLEMENTATION 29
7.0 - ENVIRONMENTAL REVIEW 31
8.0 - PUBLIC PARTICIPATION 32
FIGURES
1. Union County Sewer Service Areas
2. Twelve Mile Creek Sewer Service Areas
3. Twelve Mile Creek Basin - Existing Facilities
4. Site Plan -Twelve Mile Creek WWTP
5. Process FlowSheet-Twelve Mile Creek
6. Projected Wastewater Flow
7. General Soils Map
8. Alternate 1 - Expand WWTP
rvC 'OPT. G1=
9. Alternate 2 - Land Application AND N T!
10. Alternative 3 - Pump to Charlotte -Mecklenburg Utilities
11. Recommended Site Plan
12.A Recommended Process Flow Sheet
12.B Recommend Solids Process Flow Sheet
DEC 0 2 200A
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APPENDICES
A. Wastewater Flow Projections
B. Project Site Data
C. Cost Estimates
D. Collection System Data
■ Spill History
• Non -Discharge Permit Summary
• Infiltration/Inflow Analysis
E. Sludge Management Plan
F. User Charge Analysis
G. Environmental Review
• E/A Document
• FONSI
H. Public Hearing Summary
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SECTION 1.0 - EXECUTIVE SUMMARY
1.1 Current Situation
Union County operates a wastewater utility system in the Crooked Creek basin serving
the Towns of Stallings and Indian Trail; and in the Twelve Mile Creek basin serving the
Towns of Waxhaw, Weddington, Wesley Chapel, and portions of the Towns of Mineral
Springs, Stallings, and Indian Trail. The County also operates other smaller facilities on
Goose Creek (Hunley Creek), Clear Creek (Tallwood), Grassy Branch, and a land
application plant on NC 218 and owns 1.9 mgd of capacity in the City of Monroe's
Richardson Creek WWTP.
The Twelve Mile Creek sewer service basin is the largest in the County, containing
approximately 84 square miles of area. The largest of fhe County -operated treatment
facilities is the Twelve Mile Creek Wastewater Treatment Plant in Waxhaw, which has a
permitted capacity of 2.5 mgd. In addition to the treatment plant, the wastewater
system includes approximately 36.6 miles of 12-inch through 48-inch diameter trunk
sewers, and approximately 147.7 miles of 8- and 10-inch gravity collection sewers. There
are several pumping stations within the Twelve Mile Creek sewer service area from
relatively small facilities serving residential subdivisions, to the 1,063 gpm pump sfation on
the West Fork of Twelve Mile Creek.
An Infiltration/Inflow (1/1) Analysis was conducted on the sewer system in the Twelve Mile
Creek system, based on records from the year 2003. The infiltration rate was estimated to
be about 466 gpd per inch mile of sewer. The inflow rate was determined for fhe single
highest flow day in 2003, and was 177 gallons per person served. Both the infiltration and
inflow estimates are not considered excessive, based on accepted ranges established
by NCDENR.
An assessment of future needs was made taking into consideration current flows and
population growth data. It is estimated that by the year 2005, the total flow expected at
the Twelve Mile Creek Wastewater Treatment Plant will be approximately 2.83 mgd. By
2010, this value is expected to increase to about 5.15 mgd. Based on the current rated
capacity of the Twelve Mile Creek Treatment Plant (2.5 mgd), it is evident that additional
capacity must be provided to meet projected growth.
1.2 Alternatives
Based on the analysis of needs, it has been determined that Union County should
provide a total capacity of about 6.0 mgd to meet flows anticipated by the year 2015.
This capacity should be available by the end of 2005 in order to meet projected flows at
that time.
A number of alternatives were identified to meet capacity needs in Union County. These
include expanding the capacity of the Twelve Mile Creek WWTP to 6.0 mgd; constructing
a 3.0 mgd land application system to operate in conjunction with the existing facility;
and by purchasing 3.0 mgd of capacity in the Charlotte -Mecklenburg Utilities system,
located along the Six Mile Creek basin. In addition, a "no action" alternative was
considered, but found to be not responsive to current and projected needs. Water reuse
is also a viable means of reducing dependence on additional discharges of treated
wastewater. At this point the County is pursuing reuse opportunities; but it is not
anticipated that reuse will result in any short term significant reduction in dependence on
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additional treatment plant capacity; and thus is not an alternative to meet capacity
needs.
1.3 Evaluation of Alternatives
The three alternatives which involve expansion of capacity to 6.0 mgd were evaluated
on both a capital and present worth basis. The alternative having the lowest capital
cost, as well as the lowest present worth cost, is to expand the existing Twelve Mile Creek
Wastewater Treatment Plant from 2.5 mgd to 6.0 mgd. The capital cost of this expansion
is about $12.3 million; and the present worth of this alternative is about $33.8 million.
Based on both capital and present worth costs, the selected alternative is to expand the
existing Twelve Mile Creek Wastewater Treatment facility by fhe addition of a new
headworks system; expanded influent pumping; two (2) additional oxidation ditches; two
additional secondary clarifiers with return and waste sludge pumping; effluent filters; and
ultraviolet disinfection. An additional sludge digester with blowers would also be
provided.
An evaluation of sludge management alternatives has also been conducted as a part of
the plan to expand capacity. Currently fhe County relies on aerobic stabilization of
waste activated sludge with disposal on agricultural lands. This alternative was
evaluated and determined to be the most cost effective for continued operations within
the County.
As noted above, reuse is an option that the County will pursue as future opportunities are
identified. At this time the County does not have permits to operate any of its treatment
facilities as reuse systems.
1.4 User Charge and Financial Capability
Union County has analyzed the impact of the added debt service and operations and
maintenance costs on the Sewer Enterprise fund, and has determined that the financial
impacts of this project can be absorbed without a rate increase. The projected sewer
bill of a customer using 5,000 gallons per month will be $25.75 per month, or 0.61% of the
County Median income; and is well below the 1.5% threshold established by Construction
Grants and Loans as a "high cost project."
1.5 Program Implementation
Based on the results of the 201 Facilities Plan, it is recommended that Union County
immediately construct an expansion of the existing Twelve Mile Creek Wastewater
Treatment Plant. The first phase of expansion will increase capacity from 2.5 to 6.0 mgd,
and is expected to meet needs through 2015. At the end of that time, a subsequent
expansion from 6.0 to 9.0 mgd will be required to meet 20-year needs.
The alternative of constructing two (2) 3.0 mgd expansions was compared to building a
single 6.0 mgd expansion. The present worth of either option is essentially the same, at
approximately $33.0 million. There is no compelling justification to build an additional 6.0
mgd per day of capacity atthis time; and it is recommended that the County continue
with its plans to phase construction with a 3.0 mgd expansion at ah expected cost of
$12.3 million.
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1.7 Environmental Review
As a part of the NPDES permitting activities, an Environmental Assessment was prepared
for this project. This E/A document has undergone a rigorous review through the State
Clearinghouse process; and on September 7, 2004, a Finding of No Significant Impact
{FONSI) for the project was issued by the Division of Water Quality.
1.8 Public Participation
(To be included when the Public Hearing is completed).
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SECTION 2.0 - CURRENT SITUATION
2.1 Background
Union County is undergoing rapid change, as evidenced by population growth, much of
which is occurring in the areas which border Mecklenburg County. The County operates
a wastewater utility system which serves much of this area. The County sewer system
began service in the 1970's, serving Marshville, a poultry processor, and Wingate. Later,
the County's system was expanded to provide sewer service to the Town of Waxhaw
and the industrial park adjacent to the Monroe Airport.
By 1990, a wastewater treatment facility, trunk sewers, pumping facilities, and collection
sewers were constructed to serve many portions of the Towns of Stallings and Indian Trail.
This system serves the Crooked Creek basin. The WWTP has been expanded twice since
being placed in service, and is now rated at 1.9 million gallons per day (mgd).
By the late 1980's, the land application treatment facility at the upper reach of Twelve
Mile Creek on Goldmine Road was operating above its rated capacity; and another
land application facility in Waxhaw, also on Twelve Mile Creek, was near its capacity. In
1997 a new, state of the art wastewater facility, rated at 2.5 mgd, was placed in service
at the Waxhaw site; and large diameter trunk sewers were extended up the creek to
Goldmine Road, effectively opening all of the East Fork of Twelve Mile Creek to sewer
service.
In the early 1990's, a privately funded wastewater treatment facility was constructed on
Goose Creek near Stevens Mill Road to serve developments in this area. Union County
later acquired this treatment plant, known as the Hunley Creek facility, and the
collection lines associated with the system. The plant has been expanded once, and is
now rated at 0.231 mgd. Plans are underway to divert this flow to the Twelve Mile Creek
WWTP.
Further north in the County are three (3) other treatment systems. Two were constructed
with private funding but now owned and operated by Union County. The older of these
two systems is the Tallwood Wastewater Treatment Plant, located on Clear Creek near
the Union/Cabanas County tine. This is a small (0.05 mgd) package system. Another
facility, Ode Sycamore, is located off NC 218 near the Mecklenburg County line. This
plant is a non -discharge facility, and is rated at 0.] 50 mgd. The final County treatment
facility was constructed in the mid 1990's to serve schools and residents in the Unionville
community. This plant, known as the Grassy Branch facility, is rated at 0.050 mgd; and
discharges to Crooked Creek near NC 218. Figure 1 illustrates the location of each
facility.
In addition to these publicly owned treatment facilities, there are three privatelyowned
systems serving Hemby Acres, Fairfield Plantation, and Country Woods, along with other
developments in the area.
2.2 Sewer Service Areas / Facilities
Union County provides wastewater services in five (5) major drainage basins. Service
areas generally extend along the western portions of the County along the Mecklenburg
County boundary and eastward along US 74 to Wingate and Marshville.
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The Twelve Mile Creek basin is fhe largest sewer service basin in Union County, and
extends from fhe Sun Valley area at Old Charlotte Highway, downstream to below the
Town of Waxhaw. The Union County towns of Wesley Chapel, Mineral Springs, Waxhaw,
and portions of the Towns of Weddington, Stallings and Indian Trail are located within this
basin. The Twelve Mile Creek basin is approximately 84 square miles in size. Figure 2
illustrates the area included in this sewer service basin, and the major facilities serving this
area, which are described below:
A. Twelve Mile Creek WWTP
The Twelve Mile Creek WWTP (Permit NC 0085359) is a 2.5 million gallons per day
(mgd) "advanced secondary" treatment facility located on the existing Waxhaw
Land Application site, about 4,000 feet downstream of NC Route 16. The
treatment plant includes an influent pumping station; headworks with screening
and grit removal; parallel biological treatment units consisting of fermentation
tanks, anoxic tanks, and oxidation ditches. Mixing and aeration of the ditches is
by 100 horsepower (Hp) surface aerators.
The plant also includes secondary clarifiers, recycle/waste sludge pumping,
filtration, UV disinfection, and effluent cascade re -aeration. Solids handling/
stabilization is by aerobic digestion. Solids disposal is by land application. In 2001,
a 1.0 million gallon (MG) aerated sludge holding tank was added. Figure 3
illustrates the site location for the existing treatment plant. Figures 5 and 6 show
the existing site plan and process schematic.
Operating data for calendar year 2003 are compared to the NPDES Permit Limits
in Table 1, and illustrate that the facility consistently meets all operating .
parameters.
Table 1
2003 Performance Summary
Twelve Mile Creek WWTP
Parameter
NPDES Limit
Actual Value
Flow, mgd
2.50
1.62
BOD5, Summer, PPM
5.0
0.56
BOD5, Winter, PPM
10.0
0.47
NH3-N, Summer, PPM
2.0
0.53
NH3-N, Winter, PPM
4.0
0.23 •
TSS, PPM
30.0
1.19
Total Phosphorous, #/day
20.85
15.32
Fecal Coliform, per 100 ml
200
8.25
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DO, PPM
6.0
8.78
The above values are based on monthly averages; except for total phosphorous,
which is based on an annual average with a maximum monthly value twice the
average annual limit. Plant performance is excellent. The facility operated at
about 65% of design for the year 2003.
B. Wastewater Collection System
The wastewater transport system in the Twelve Mile Creek basin was constructed
in 1996 - 1997, and placed in service in 1997, when construction of the Twelve
Mile Creek Treatment Plant was completed. The exception is the collection
system serving the Town of Waxhaw, which is much older. There are no good
historical records describing the Waxhaw system; however, it is likely that much of
the collection system in Waxhaw is over 50 years old.
The majority of the collection system (except the Waxhaw system) is constructed
of modern materials, is well maintained and in excellent condition. On the other
hand, the Waxhaw system experiences high rates of infiltration/inflow (I/1), and
there are current construction projects which will address known problems in
Waxhaw.
Union County Public Works supplied a summary of reported collection system spills
dating back to September, 1999. During this five-year period there were twenty-
five (25) reported spills. The summary of spills is attached in Appendix D. Nine of
the spills were attributed to one pump station, and this problem has now been
corrected. This accounted for 128,116 gallons, or 20.3 percent of the reported
spills. The single largest spill occurred in January, 2001, as a result of a
construction project. This spill, estimated at 466,000 gallons, accounts for 73.6
percent of the reported spills over the past five years.
Much of the land area within the basin is currently unsewered, since prior to 1998,
all development except in Waxhaw relied on septic tanks. The County has no
plans to sewer these areas at present. There are no known unsewered areas
within the Twelve Mile Creek sewer service area That are contributing to health or
water quality issues.
A number of interceptor sewers, pump stations, and force mains have been
constructed to convey wastewater into the treatment plant. These are illustrated
schematically on Figure 2 and described below.
1. The Twelve Mile Creek Interceptor extends from the plant site up the East
Fork of Twelve Mile Creek to the headwaters of the basin in the Sun Valley
area. The interceptor leaves the plant as a 48-inch diameter reinforced
concrete pipe, and progressively reduces in diameter to a 15-inch line at
Goldmine Road. The main portions of this line were constructed in 1996-
1998.
2. The Price Mill Creek interceptor is a tributary of the East Fork Twelve Mile
Creek. This line begins below Chambwood Road and extends upstream
to near Pioneer Lane. Pipe sizes range from parallel 24- and 15-inch pipe
at the lower end, 24-inch pipe from NC 84 to Hawfield Lane, and 15- and
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12-inch pipe above that point. The portions of this line above Hawfield
Lane were constructed in_1996-1998, along with about 4,500 feet of 15-
inch pipe to a point near NC 84. The balance of the project was
constructed in 2000/2001.
3. A tributary of Price Mill Creek is Davis Mine Creek. In 1987, a 15- and 12-
inch sewer was constructed from near Fincher Road upstream to near
Chestnut Land and Potter Road. This line connects to the Price Mill Creek
sewer.
4. Phase 1 of the West Fork Twelve Mile Creek interceptor was completed in
2001. This line consists of 4,500 feet of 42-inch pipe up fhe West Fork of
Twelve Mile Creek to Rogers Branch, and 5,000 feet of 12- and 10-inch
PVC pipe along Rodgers Branch to Newtown Road.
5. In 1999, a 10-inch PVC sewer was constructed along Still House Branch
from the treatment plant upstream to Newtown Road.
6. Beginning just south of NC 84, 15- and 12-inch trunk sewer extends
upstream Culvert Branch to serve the Weddington School complex and
areas upstream of Twelve Mile Creek Road. This line was recently
extended to Beulah Church Road. This line connects to the Deal Road
pump station.
7. In 1985 a 12-inch sewer was constructed to convey wastewater from
Waxhaw to the influent pump station for the Land Application facility. This
line has been reconnected into the Twelve Mile Creek WWTP.
8. A 30-, 24-, 18-, and 15-inch line has been constructed on Little Twelve Mile
Creek. This line extends sewer service to NC 75 and areas around Mineral
Springs.
9. The Blythe Creek sewer is a 24-inch line, which expands service to
Waxhaw.
10. An 18- to 12-inch trunk line was installed from a new pump station near
Forrest Lawn Road to a point north of Chestnut Lane. The pump station
discharges into the Davis Mine Creek line, and allowed four (4) existing
pump stations to be abandoned.
The County staff keeps an updated inventory of the trunk lines and collection
lines which have been constructed within fhe Twelve Mile Creek basin. As of
June, 2004, the County reported the following data on its collection system:
1. For permits issued through April, 2004, there are about 780,000 feet (147.7
miles) of 8- and 10-inch gravity sewers in the Twelve Mile Creek basin.
2. There are approximately 193,200 feet (36.6 miles) of 12- through 48-inch
interceptor sewers installed.
3. An estimated total 1966 "inch -miles" of gravity sewers has been installed
or permitted through June, 2004.
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A summary of the Non -Discharge Permits for the Twelve Mile Creek Basin is
included in Appendix D.
C. Wastewater Pump Stations
There are several pumping stations in the Twelve Mile Creek service area that
currently convey wastewaters into existing components of fhe interceptor system.
Three of these are described below.
1, In 1996, the Deal Road pump station was built on Culvert Branch near NC
84 to serve the Weddington Schools complex. The station is equipped
with two 325 gpm pumps, and discharge through an 8-inch force main
along NC 84 to the Lower Price Mill Creek system.
2. Limited sewer service is also provided in the Lanes Creek basin, where a
pump station conveys wastewater from the JAARS facilities into the Town
of Waxhaw, and subsequently to the Twelve Mile Creek WWTP. •
3. A new 1,063 gpm pump station is in operation on the West Fork Twelve
Mile Creek.
There are numerous (15±) other smaller stations in service in the Twelve Mile Creek
basin.
D. Crooked Creek Diversion Project
Union County recently completed construction of a major wastewater
interceptor, pump station, and force main in the North Fork Crooked Creek .
drainage basin. This project can divert up to 1.2 mgd into the Twelve Mile Creek
basin on an interim basis to meet capacity needs in the Crooked Creek area of
Union County. These improvements include 16,500 feet of 36- to 15-inch sewers, a
2,100 gpm pump station, and 40,000 feet of 16-inch and 12-inch force mains.
These major facilities are shown on Figure 2. It is expected that this diversion will
be required for up to ten years, or whenever the planned regional wastewater
facility to serve northern Union County becomes a reality.
2.3 Population and Demographics
In 1999/2000, Union County prepared an update of the Water and Sewer System Master
Plans. The first step in this effort was to prepare a comprehensive population growth
model to be used to project water and wastewater service needs. The growth model
assigned population in five year time steps to each census tract in the County.
This population model utilized census data, building permit records, development plans
approved by the Union County Planning Department and the County's Land Use Plan to
establish target populations in each census tract in five-year time steps for a 20-year
planning period. In addition, "buildout" populations were determined based on the
County Land Use Plan.
The population growth model compared data from a variety of sources, including the
NC Office of State Planning and Claritis, as well as localized information on building
permits and approved subdivision plans. Growth of new "water only" accountsin
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westem Union County in the late 1990's was also considered. Growth from 1995 to 1999
occurred at an annualized rate of 4.7%.
This growth model predicts that the County population will more than double over the
next 20 years, with most of the growth occurring in western portions of the County. This
model is more aggressive than current OSPL data; but has been accepted by the
County as the guide to planning for water/sewer service needs. Based on the
population/growth model, the 2002 population in Union County was estimated to be
123,677. A more detailed discussion of population and demographics is included in the
Section on Future Needs.
2.4 Infiltration / Inflow
An infiltration/inflow (1/I) analysis has been conducted for the Twelve Mile Creek system,
and a summary is included in Appendix D. For this analysis, precipitation and wastewater
flow records for calendar year 2003 were utilized. Base use or expected flow was
estimated from County water billing records, treatment plant flow data, and
precipitation data.
Expected use was determined from billing records from January to March, 2004, a period
which would exclude non -potable uses such as lawn watering. For this period the
average water used was 163 gallons per meter per day. With an average household size
of 2.7 persons, the per person use for this period was 60 gallons per day.
Rainfall data from NOAA for 2003 were reviewed. The months February through April,
2003 were the three wettest consecutive months. For this period the total recorded
rainfall was 21.03 inches, or about 50% above the normal average of 14.01 inches.
Wastewater flow data for this period were obtained. The average daily flow at the
Twelve Mile Creek WWTP for February to April, 2003, was 1.967 mgd. Expected flow for
the period was determined by multiplying the estimated population served by the
average water billed minus consumptive loss of 10%. For the period, the estimated
population served by the Twelve Mile Creek Facility (Union County Master Sewer Plan)
was 19,200. The expected flow from residential sources was determined by using a per
capita value of 54 gallons per person per day. Using this approach, the expected flow
was about 1.036 mgd. This number should be increased by approximately 0.103 mgd to
account for use by schools and industrial sources, bringing the total expected flow to
about 1.139 mgd.
Flow attributed to I/I in April, 2003 was 0.743 mgd. In January, 2003, the estimated total
inch -miles of gravity sewers installed was 1774. The 1/1 for this period was estimated to be
466 gpd/inch-mile. By NCDENR criteria, this is not excessive. The 1/1 on a per person basis
for this period is about 43 gpd per person.
Inflow is the extraneous flow entering the sewer system following a significant rain event.
For the Twelve Mile Creek system, the maximum 24-hour flow recorded at the treatment
plant was in July, 2003. The maximum 24-hour flow was 3.4 mgd. Dividing this value by
the estimated 19,200 persons served yields a per capita peak flow of 177 gallons per day.
This value is below the level established by NC DENR of 275 gallons per day, and is
considered to be non -excessive.
2.5 Future Needs
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The population projections and their distribution by census tract were used to determine
wastewater flows for the Twelve Mile Creek Sewer Service area. The following
assumptions were utilized:
A. For existing sewered areas, 100% of new growth would be served by the
wastewater system.
B. For currently unsewered areas, no wastewater flows would be generated from
population growth until trunk lines were built. Growth occurring up to that time
will not be served; but 100% of growth thereafter will be served.
C. Existing residents currently on septic systems, and new residents served by septic
systems built before trunk sewers are constructed will probably not connect to The
sewer system within the 20-year planning period.
D. For the purpose of estimating flows for the Treatment plants, 100 gallons per day
per person (or 270 gallons per household) was assumed, even though current
State regulations require non -discharge permits to be based an 360 gallons per
household per day. The estimates of per capita use, minus consumptive loss, plus
allowances for 1/1 discussed previously, show that a per capita value of 100 gpd is
reasonable.
Appendix A presents a summary of the population projections for the Twelve Mile Creek
basin.
As a part of Master Sewer Plan implementation, phasing of trunk sewer construction in
each basin was discussed at several public/stakeholder work sessions. A recommended
plan of construction was then prepared which included the following for the Twelve Mile
Creek area:
A. Phase 2002 - 2005
1. Construct Little Twelve Mile Creek Trunk Sewer. (Completed) .
2. Construct Blythe Creek Trunk Sewer towards the Town of Waxhaw.
(Completed).
3. Construct Davis Mine Creek trunk sewer and decommission two (2)
existing pump stations. (Completed).
B. Phase 2005 - 2010
1. Extend the West Fork Twelve Mile Creek line from Rodgers Branch
upstream to the Springhill Pump Station. (Partially completed).
2. Construct trunk line along Rhone Branch.
3. Construct a trunk line along Keels Creek to NC 84.
4. Extend trunk lines along Mundy's Run, Culvert Branch, and other unnamed
tributaries of the West Fork Twelve Mile Creek towards Mecklenburg
County.
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The Culvert Branch line has been completed. The upper third of Project B.1 and a
1,063 gpm pump station to extend service above Forrest Lawn Road is also
complete.
The County capital plan will open essentially all of the Twelve Mile Creek basin to sewer
service by 2010. It now appears that all areas may be served by the trunk sewer system
earlier than planned. However, the currently "accepted" phasing plan has been used
to prepare the flow projections used in this Facilities Plan Amendment.
A significant influence on flows directed to the Twelve Mile Creek WWTP is the status of
planning/permitting for a regional wastewater facility discharging to the Rocky River in
northern Union County. Planning for this facility has been underway for nearly ten years.
The possible presence of the Carolina Heelsplitter, a Federally protected species in
Goose and Duck Creeks, has delayed implementation of this project. To provide
needed sewer capacity in the Upper Crooked Creek basin, Union County has
constructed a major wastewater diversion project on the North Fork Crooked Creek,
described in Section 2.2.D. This facility will divert flow from the Crooked Creek basin into
the Twelve Mile Creek system.
An additional factor impacting flows to the Twelve Mile Creek WWTP is the planned
"mothballing" of the County's Hunley Creek WWTP, which discharges into Goose Creek.
Flows will be diverted to the North Fork Crooked Creek system and subsequently Twelve
Mile Creek. Diversions to Twelve Mile Creek will begin in early 2005.
Wastewater flows originating in the Crooked and Goose Creek basins (areas currently
served by Union County) have been projected through the year 2010, and assume that
no new significant sewer service area expansions occur before that time. Flows
anticipated to be diverted into the Twelve Mile Creek WWTP assume that the Crooked
Creek WWTP operates at a "base" capacity of 1.5 mgd, or about 80% of its 1.9 mgd
NPDES permited flow. These projections are Tabulated in Appendix A, and summarized in
Table 2.
Table 2
Wastewater Row Projections, mgd
Crooked/Goose Creek Basin
Year
Total Projected
Flow, mgd
Crooked Creek WWTP
Base Operating Capacity, mgd
Flow Diverted to
Twelve Mile Creek mgd
2000
1.1697
1.1697
0 •
2005
1.8943
1.5000
0.3943
2010
2.26250
1.5000
1.1250
Appendix A also includes a tabulation of the flows projected within the Twelve Mile
Creek WWTP. These estimates reflect the adopted phasing plan for sewer construction
and the diversions from Crooked Creek. Table 3 summarizes the estimates of wastewater
flows to the Twelve Mile Creek WWTP. Figure 6 shows the projected flows graphically.
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Table 3
Wastewater Flow Projected, mgd
Twelve Mile Creek Basin
Year
Twelve Mile
Creek Flow
Crooked Creek
Diverted Flow
Total, mgd
2000
0.903
0
0.903
2005
2.435
0.3943
2.8293
2010
4.026
1.1250
5.1510
2020
6.859
0
6.859
Twelve Mile Creek wastewater flows assume the regional facility in northern Union County
will be available by 2010, allowing diversions from Crooked Creek fo be discontinued at
that time.
Trends presented in Appendix A illustrate That Union County must provide a total
treatment capacity of 2.83 mgd by 2005, and 5.15 mgd by 2010 to meet projected
needs. This will provide capacity needed to meet the 2010 projections in Twelve Mile
Creek, plus flow diverted from Crooked Creek. If Union County resolves regulatory
concerns and is able to discontinue wastewater diversions from Crooked Creek by the
2010/2010 timeframe, no further expansion of Twelve Mile Creek will be needed until
about 2015. At that time a total capacity expansion of 9.0 mgd is anticipated.
There are many factors that influence flow projections and their relationship to measured
flows at each of the treatment plants, including actual per capita water use, growth and
climate. Between 1998 and 2003 Union County experienced four (4) consecutive years
of unprecedented drought, with rainfall totals well below long term average. Water use
was restricted in hot months. While the restrictions were for activities such as lawn
watering, it is likely that conservation reduced wastewater discharges. Also,
groundwater levels were at or near historic lows, reducing "normal" I/1 contributions to
the sanitary sewer systems. However, once rainfall returns to "normal" levels, flows will
increase. Thus, it seems prudent to plan for and implement system expansions based on
valid long term trends that reflect normal climatic patterns.
Development continues at a rapid rate in western Union County. According to Union
County Public Works, Non -Discharge Permits have been issued for a total of 8,997
residential connections into the Twelve Mile Creek WWTP, which will potentially result in
upwards of 3.8 mgd of wastewater flow, not including diversions from Crooked Creek. To
provide required treatment capacity, Union County should immediately proceed with
plans to increase wastewater treatment capacity in the Twelve Mile Creek basin to a
total of 6.0 mgd.
Union County is evaluating options to implement a reclaimed water program that will
substitute reclaimed water from two existing treatment facilities (Twelve Mile Creek and
Crooked Creek) for potable water for specific bulk uses such as construction and
irrigation of landscaped areas. The County is proceeding to have the two facilities
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above re -permitted to allow this practice. The County is seeking potential customers for
metered reclaimed water use, and will evaluate all opportunities on a case by case
basis.
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SECTION 3.0 - WASTEWATER DISPOSAL ALTERNATIVES
3.1 Background
Union County has utilized land based disposal, connections to other publicly owned
treatment works (POTW's), and development of its own POTW's with surface discharge to
meet the capacity/treatment needs of the growing customer base. The selection of
alternatives has historically been made based on available options, feasibility, and cost.
The existing Twelve Mile Creek WWTP was designed and permitted for a flow of 2.5 mgd.
Past performance and actual wastewater characteristics confirm that the existing facility
is capable of meeting current NPDES Permit limits. (See Table 1).
The NPDES Permit for the Twelve Mile Creek WWTP was renewed, effective January 1,
2003. The new permit included two (2) major new requirements:
A. Established new discharge limit and monitoring requirements for total
phosphorous, expressed as a total mass daily load (TMDL). Permit limits set the
TMDL at 20.85 lbs./day (12 month average). This is equivalent to a concentration
value of 1 mg/I at a flow of 2.5 mgd. The existing Twelve Mile Creek WWTP was
designed to achieve a 1 mg/I effluent total phosphorous, utilizing biological
nutrient removal (BNR) technology. The biological capability is further enhanced
by the addition of alum feed and effluent filters.
B. Established limits for total copper and zinc, and provides a schedule of
compliance to achieve required limits.
Past performance of the Twelve Mile Creek WWTP illustrates that significant reduction in
total phosphorous occurs in the process. Union County does not anticipate undue
problems meeting the current TMDL for phosphorous using the BNR process plus chemical
treatment, if necessary. Based on a recent site specific metals analysis, metal limits are
not expected to be an issue.
As a preliminary step in preparing this Engineering Alternatives Analysis, stream flow data
on Twelve Mile Creek at the existing point of discharge were requested from the US
Geological Survey (USGS). A copy of this information is in Appendix B. At the existing
discharge, the average annual stream flow is 72.7 cfs; the 30Q2 is 3.2 cfs; and the 7Q10 is
0.1 cfs.
Also, since one option for added capacity will be to expand the existing POTW,
speculative effluent limits were requested from NCDENR. A copy of the limits is also
included in Appendix B.
3.2 Re -rating of the Twelve Mile Creek WWTP
As a part of the strategy to provide additional capacity, Union County may request a
modification of the NPDES Permit to increase the capacity of the existing facilities by 0.5
mgd to a capacity of 3.0 mgd. An engineering analysis of the existing facilities indicates
that on the basis of past performance, wastewater characteristics, and present NPDES
Permit limits, this capacity can be attained. Critical observations include:
A. The oxidation ditches can meet design requirements at a projected flow of 3.1
mgd.
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B. The UV disinfection system is capable of meeting disinfection requirements at
peak flows of about 8.0 mgd, or 3.2 mgd average daily flow.
Application for the NPDES modification for the additional capacity has not been made.
However, for the purposes of this analysis, it is assumed that the existing facilities will be re -
rated to a flow of 3.0 mgd. Alternatives discussed below are based on providing an
additional 3.0 mgd of capacity by 2005, and another 3.0 mgd by 2015.
3.3 Alternatives
Wastewater flow projections presented in Section 2.5, Table 3 show that by 2010 the
average daily flow at Twelve Mile Creek will be about 5.15 mgd. For planning purposes,
Union County should have an available capacity of about 6.0 mgd, which is about 15%
above the projected average flow. These projections also show that flows will be about
6.9 mgd by about 2020, assuming that the Crooked Creek diversion has been
discontinued. The alternatives being considered in this analysis would provide 6.0 mgd of
capacity by about 2004. An additional 3.0 mgd capacity expansion will be required by
about 2014 to meet 20 year flows.
Alternatives evaluated herein are based on continued operation of the existing Twelve
Mile Creek facility of a re -rated capacity of 3.0 mgd. Additional capacity will be
provided in 3.0 mgd increments by one of the Three options listed below:
A. Expand the existing surface discharge facility from 3.0 to 6.0 mgd by 2004, and
from 6.0 to 9.0 mgd by 2015.
B. Construct a land -based spray irrigation system with a rated capacity of 3.0 mgd.
Expand the system by 3.0 mgd in 2015.
C. Discharge 3.0 mgd into the Charlotte -Mecklenburg Utilities system on Six Mile
Creek. Increase the allowable discharge to 6.0 mgd by 2015.
D. Water Reuse.
E. No Action.
Each of these options is discussed in the following sections.
The "no action" alternative above is not an acceptable option. First, Union County has
operated the existing Twelve Mile Creek WWTP since early 1998, and has achieved an
excellent record of compliance with existing NPDES requirements. When the treatment
plant was planned in the early 1990's, Union County made clear its intentions to expand
the facility if necessary to meet future needs. The site plan and other engineering
documents showed how facility expansion would be facilitated. Since that time the
County has issued Non -Discharge Permits to connect additional customers to the system.
As noted in the prior section, Union County has issued permits that could result in an
additional 3.8 mgd of wastewater. This, in combination with current flows of around 2.0
mgd, greatly exceeds the plant capacity. Thus, the "no action" alternative is not viable,
nor does if respond to the realities of growth in western Union County.
The evaluation of alternatives to provide an additional 3.0 mgd in capacity considers the
facility capital cost, operations and maintenance to identify the "present -value -of -cost"
of each option.
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A. Expand the existing Twelve Mile Creek WWTP in 3.0 mgd increments.
This alternative will provide for the following modifications/additions to the existing
treatment plant:
1. New headworks/pumping with fine mechanical screens and odor control.
The existing influent pump station will be modified to provide a rated
capacity of 6.0 mgd (15.0 mgd peak). A new 750 kW emergency
generator will be provided.
2. A new 3.0 mgd "liquid process" line consisting of parallel oxidation
ditches, new parallel 85-foot diameter secondary clarifiers, new recycle/
waste sludge pumping, two (2) more effluent filters, parallel UV
disinfection system, and related process piping.
3. New 1.0 MG aerobic sludge digester with diffusers and new blower
building.
4. New 750 kW emergency generator with primary switchgear for the liquid
process facilities, and all other site electrical and instrumentation.
A further 3.0 mgd expansion will be needed by around 2015.
B. Construct land -based treatment system.
1. This alternative would utilize the existing Twelve Mile Creek WWTP at a
capacity of up to 3.0 mgd. The additional capacity would be provided
by constructing a land application system, initially rated at 3.0 mgd, and
expandable to 6.0 mgd.
2. New headworks with fine screens and odor control would be constructed
ahead of the existing influent pump station. A new influent station and
force main will be constructed to convey wastewaters to a remoie
stabilization lagoon site.
3. Construct stabilized waste holding basin(s) and pumping facilities to
individual land treatment sites.
4. Construct land stabilization sites consisting of piping and fixed spray
nozzles.
The cost analysis includes land and improvements for a 6.0 mgd system.
C. Connect to Charlotte -Mecklenburg Utilities (CMU) at Six Mile Creek.
Union County currently has a contract with CMU for sewer service in the Six Mile
Creek basin. The contract provides for up to 3.0 mgd of capacity. The County
has exercised its rights for 1.0 mgd in capacity to serve Six Mile Creek. This analysis
assumes that the existing agreement would be applicable for an additional 3.0
mgd of capacity in this system with a further expansion to 6.0 mgd by 2015.
Required facilities include:
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1. Construct new headworks with fine screening and odor control, and a
new influent pump station dedicated to pumping flow to the Six Mile
Creek trunk sewer. The station would be rated for an average daily flow
of 3.0 mgd, and be expandable for future flows.
2. Construct a 24-inch diameter force main from the pump station at Twelve
Mile Creek to the Six Mile Creek basin. The force main discharges to a 36-
inch gravity sewer connection to the Six Mile Creek line.
3. Purchase an additional 3.0 mgd of capacity in the Charlotte -
Mecklenburg Utilities system in accordance with existing contracts. Under
these arrangements, Union County "purchases" capacity in all applicable
components, and then pays a treatment charge for operation of the
conveyance and treatment components. The County is responsible for all
future costs related to new permit requirements or improved operations or
reliability.
By 2015 another 3.0 mgd increment of capacity would be added.
Each of these alternatives will provide a total treatment capacity of 6.0 mgd by
2005, and 9.0 mgd by 2015.
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SECTION 4.0 - EVALUATION OF ALTERNATIVES
4.1 Background
Alternatives discussed in Section 3.3 will each meet projected wastewater capacity
needs of 6.0 mgd by the year 2005, and 9.0 mgd by 2015. The alternatives have been
evaluated on the basis of present worth or present value of cost in accordance with
prescribed criteria.
Present worth is a method of economic analysis that considers capital costs, operations
and maintenance costs, and residual or salvage value over a predetermined period (in
this case, 20 years) at a specified discount rate (1 = 6.125%) for each alternate. The
alternate with the lowest present value of cost or present worth is considered to be the
most cost effective of those being considered. The procedures for determining present
worth are described in "Guidance Document to Evaluate Wastewater Disposal
Alternatives," published by NCDENR, June 9, 2000.
Each alternative is further described in the following sections. Capital cost estimates,
along with applicable operations and maintenance estimates for each alternative have
been prepared.
It should be noted that the present worth analyses assume that the existing Twelve Mile
Creek WWTP will be an integral part of any wastewater solution. For each altemative,
the present worth analyses represent the costs above/beyond current costs that will be
required to meet long term needs. Appendix C includes summaries of the total capital
cost and present worth cost for each alternate. Figure 7 is a general soils map of Union
County. Figures 8, 9, and 10 illustrate the conceptual arrangement of facilities for each
alternative.
4.2 Expand the Existing Twelve Mile Creek WWTP
This option was envisioned when the current facility was permitted/constructed in 1996-
1998. The existing site layout was prepared to easily double the system rated capacity.
Space was provided in the site plan for new oxidation ditches, clarifiers, filters, and
disinfection units. Much of the process piping was installed to facilitate new process
tanks.
In addition, the existing treatment process utilizes oxidation ditch technology to achieve
biological removal of phosphorous down to concentrations of 1.0 ppm. Alum addition
was also included in the original design to promote solids flocculation/removal during
process upsets. Alum is traditionally employed to reduce phosphorous concentrations
below 1.0 ppm. In 2001, Union County constructed another aerobic digester (1.0 million
gallons) to improve solids stabilization and provide sludge storage for periods such as
wet/cold weather, when land application of sludge cannot be done routinely.
Expansion of the Twelve Mile Creek WWTP will require the following improvements:
1. New headwork with one (1) "fine" mechanical screen, a screen bypass channel,
and space for a future unit.
2. Upgrade influent pump station by replacing three (3) existing pumps with three
(3) new 280 Hp units, sized so that any two pumps can meet peak capacity of 15
mgd. One existing 88 Hp pump will be kept for low flow conditions.
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3. Provide odor control system at headworks and influent pump station, along with
a new electrical switchgear building and a 750 kW generator set.
4. Parallel the existing 16-inch force main with a new 24-inch force main.
5. Provide two (2) additional oxidation tanks, two (2) additional secondary clarifiers
with a new RAS/WAS pump station, new automatic backwash filters, and a new
parallel UV disinfection unit.
6. Sludge processing will require another 1.0 MG digester with blower facilities.
7. Other improvements include an odor control system for the existing grit facilities, a
new influent splitter box, upgraded in -plant pumping, and numerous piping
changes.
8. New 750 kW standby generator with automatic transfer switch and primary
switchgear building.
The proposed expansion to 6.0 mgd will cost an estimated $12.3 million. To meet 20-year
capacity needs, another 3.0 mgd expansion in capacity will be required by about 2015.
This expansion will cost an estimated $15.9 million.
Operations and maintenance costs have been estimated taking into account chemicals
and electricity, maintenance, laboratory operations, labor, management, and sludge
disposal. The estimated cost of operations is about $1.77/1000 gallons in 2005. The unit
treatment charge is estimated at $0.70/1000 gallons by 2015, adjusted for increased flow
but not inflation of costs.
The 20-year present worth of this alternate is approximately $33.8 million.
4.3 Construct Land Application System
This alternate will require operating "parallel" treatment systems to meet capacity needs.
The existing WWTP will be re -rated and will operate at a maximum capacity of 3.0 mgd.
The land application system will be patterned after the system formerly operated by
Union County at Waxhaw, with the following modifications:
A. The Waxhaw site was permitted at an average flow of 30,000 gallons per, acre. To
achieve the rated flow of 300,000 gpd, about 100 acres of sprayfields were used.
Topography, buffers, and unusable land resulted in Union County purchasing a
250 acre site. For the proposed land application alternative, it has been assumed
that each 1.0 mgd of capacity will require 333 acres of sprayfields, and an
additional 333 acres for buffers.
B. Land in the proximity of the existing Twelve Mile Creek WWTP has increased
dramatically in price over the past decade, and is estimated at $35,000 to
$40,000 per acre. Development and resulting high land costs between Waxhaw
and western Union County essentially eliminate the availability of suitable sites.
East of Waxhaw, however, open land is available, and there are numerous "large
scale" farming operations. For this analysis, it was assumed that waste would be
pumped up to ten miles from Waxhaw to find suitable acreage for the lagoons
and sprayfields.
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Considering the above, the following facilities are required for a parallel land application
system:
A. New headworks with fine mechanical screens and space for a future unit.
B. New influent pump station with standby generator to pump from the Twelve Mile
Creek site to the lagoon/spray site.
C. Odor control system for headworks.
D. Approximately ten miles of 24-inch force main.
E. Waste stabilization and treated effluent storage system.
F. Effluent disinfection system.
G. 1,000 acres of active sprayfields with piping, sprinklers, and controls; and an
additional 1,000 acres for buffers, etc.
H. Laboratory facilities.
The project cost to provide the facilities and land for the 3.0 mgd system is estimated to
be $70.8 million. This includes the purchase of land required for a further 3.0 mgd
expansion.
By 2015, a further expansion will be required at an estimated cost of $14.9 million. Key
improvements will be expansion of the pumping system, and development of additional
lagoon/spray sites. The projected 20-year present worth of this alternative is $78.9 million.
4.4 Discharge to the Charlotte -Mecklenburg Utility (CMU) System
This alternate will require construction of a major pump station at the Twelve Mile Creek
site, and a 34,000-foot-long force main to transport wastewater to the CMU system along
Six Mile Creek in Marvin. In addition, Union County would be required to purchase an
additional 3.0 mgd of capacity in the CMU system under the terms of an existing
agreement for service in the Six Mile Creek basin. Under this agreement, Union County
purchased 1.0 mgd of capacity at a total cost of $1,765,000 for the Six Mile Creek
interceptor and pumping system; and $1,050,000 for capacity in the McAlpine Creek
WWTP. In addition, the County is responsible for its share of treatment reliability and
process improvements. There are currently three (3) major projects underway at
McAlpine (digesters, influent pumping, phosphorous removal) which will increase the
treatment capital charge by an estimated $1,491,500, bringing the total estimated
capital cost to $4,306,500 per million gallons of capacity.
The capacity purchase agreement stipulates that the purchase of additional capacity
would be based on the actual cost of the expansion of the McAlpine Creek WWTP. This
capacity is estimated to cost $6,148,000 per mgd. The total cost for conveyance and
treatment of the additional 1.0 mgd is estimated to be $7,913,000.
Facilities required to provide 3.0 mgd of capacity include:
1. New headworks with fine mechanical screens and space for a future unit.
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2. New pump station with standby generator to pump to the Six Mile Creek
Interceptor. .
- 3. Odor control system for headworks.
4. Purchase 3.0 mgd of capacity in the Six Mile/McAlpine Creek system from CMU at
a cost of $16,526.000.
The total project cost to provide the facilities for 3.0 mgd of capacity, including the
pump station and force main to Six Mile Creek, are estimated at $27,585,000. This
includes current and anticipated capital charges to CMU.
By 2015 a further 3.0 mgd expansion will be required. The cost of capacity for flows
beyond 3.0 mgd has not been addressed in the contracts for service. However, based
on a study prepared by McKim & Creed for CMU, the cost to expand McAlpine from 64
mgd to 80 mgd is about $6,148,000/mgd. The total cost to expand from 6.0 to 9:0 mgd,
including the cost in the Six Mile Creek transmission and pumping system, would be
$7,913,000/mgd. The total of the expansion from 6.0 to 9.0 mgd is estimated at
$24,567,000. The 20-year present worth of this alternative is $53.7 Million.
4.5 Evaluation of Alternatives
The three alternative have been evaluated on the basis of capital cost and present
value of cost. The basis for the evaluations and results are discussed below. Capital cost
estimates were developed for each alternative, taking into account the appropriate
improvements and facilities which will be required. Key considerations include:
A. The cost of expansion at the Twelve Mile Creek site was estimated by considering
all items needed to parallel the existing process units. There were no
improvements needed to meet current NPDES limits. The cost to expand at the
existing site was $4.10/gallon of capacity for phase 1; and about $5.30/gallon for
phase 2.
O&M costs were estimated considering both fixed and variable costs. Current
O&M is estimated at about $1.77 per thousand gallons, exclusive of debt
repayment. By 2015, as flows increase, the treatment cost will be reduced to
about $0.70 per 1,000 gallons.
B. The capital cost to use land application will be highly dependent on actual land
costs. Land in the immediate vicinity of the treatment plant has sold for nearly
$45,000 per acre. This analysis assumes that land can be purchased at $10,000
per acre within ten (10) miles of the site. The estimated capital cost of phase 1 is
about $70.0 Million, including land for a subsequent expansion. Phase 2 costs are
estimated to be $14.9 Million.
C. The capital cost to discharge into the CMU system includes the cost to construct
the pumping system ($11.1 Million), plus the purchase of capacity in the CMU
system, which is estimated at about $16.5 Million. The phase 2 capital cost
estimate, including capacity charges, is $24,6 Million. The current unit treatment
charge is $0.66 per 1,000 gallons.
The capital cost of each alternate is summarized in Table 4.
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Table 4
Estimated Capital Costs
Alternate
Phase 1
Phase 2
Total
I. Expand Twelve Mile Creek WWTP
$12,289,000
$15,877,000
$28,166,000 '
2. Land Application
$70,755,000
$14,934,000
$85,689,000
3. Pump to CMU
$27,585,000
$24,567,000
$52,152,000
The capital costs range from $28.2 Million to $85.7 Million. The alternative with the lowest
capital cost is expansion of the Twelve Mile Creek WWTP. These costs are based on the
Engineering News Record CCI of 6,589.
The "present value of cost" includes capital costs, O&M, and salvage values, all.
expressed as 20-year present worth. The presenf worth of these alternatives is shown in
Table 5.
Table 5
20-Year Present Worth Costs
Alternate
Amount
1. Expand Twelve Mile Creek WWTP
$33,758,000
2. Land Application
$78,897,000
3. Pump to CMUD
$53,701,000
The present worth of costs ranges from $33.8 Million to $78.9 Million, with expansion of the
Twelve Mile Creek WWTP having the lowest capital cost and 20-year presenf worth. Land
application has the highest present worth due largely to the high cost of land and the
distance from the current treatment plant to suitable sites. There are also very significant
differences in fhe capital and present worth costs between plant expansion and
pumping into the CMU system. Much of the difference is associated with pumping from
the Twelve Mile Creek site into the CMU Six Mile Creek system near Marvin.
Based on the significant difference in the present value of each alternative, minpr
refinements of capital and O&M costs will not change the ranking of the alternatives.
Clearly, expansion of the Twelve Mile Creek WWTP is the most cost effective alternative
available to Union County.
4.6 Selected Alternative
The selected alternative to meet the treatment capacity needs is to expand the existing
Twelve Mile Creek treatment plant. This alternative has the lowest capital costs and
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present value of cost of the three alternatives evaluated. This alternative will involve the
following construction:
1. New headworks with fine mechanical screening and odor control facilities. Two
(2) screens will initially be installed, and space for a third future unit provided.
Modifications to the influent pumps will include replacing three (3) existing pumps,
sized so that any two (2) can meet the peak hydraulic rate of 15 mgd. A new 24-
inch force main will parallel the existing 16-inch pipeline. An odor control system
will be provided for the headworks and pumping station; and a new 750 kW
standby generator will provide backup power.
2. Expansion of the biological treatment system will require construction of two (2)
additional oxidation ditch systems, which include a fermentation zone, an anoxic
zone, and an aerobic oxidation ditch. The configuration of the ditches will
duplicate the existing two units. The biological system is sized to meet NPDES limits
for BOD reduction, effluent NH3-N, and effluent total phosphorous.
3. Improvements also include two (2) secondary clarifiers with return and waste
sludge pumping, and two (2) shallow bed automatic backwash effluent filters.
UV disinfection will be expanded with the addition of a second reactor. '
4. Waste sludge facilities will include an additional aerobic digester. Land
application of stabilized sludge will be used.
5. Other site improvements include a flow distribution structure ahead of the
oxidation ditches and piping intended to facilitate uninterrupted operations and
future expansion. A 750 kW emergency generator will allow uninterrupted of all
critical process units. Finally, the existing grit removal system will be retrofitted with
an odor control system.
These improvements are shown on Figure 11, a proposed site plan for the Twelve Mile
Creek WWTP expansion. Figures 12A and 12B illustrate the process schematic of the
expanded facility.
4.7 Wastewater Reuse
Union County operates two (2) wastewater facilities capable of producing "reuse
quality" wastewater on a consistent basis, although the County does not have permits
for, or the ability to provide, reuse water.
Union County recognizes the benefits of providing reuse water when opportunities exist.
To identify potential opportunities, the Union County Public Works Department has
formed a Reuse Committee consisting of the Assistant to the County Manager, the Public
Works Director, and an Assistant Public Works Director.
The Reuse Committee is currently exploring the possibility of providing reuse water to a
mixed use development project for a site adjacent to the Twelve Mile Creek Wastewater
Treatment Plant. Potential uses would be for irrigation of landscaped areas, and
common open spaces. This application would require Union County to obtain a "Reuse
Water Permit" from NCDENR.
While the actual quantity of reuse water would initially be very limited, establishing an
ongoing program to promote reuse is a positive initiative.
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4.8 Sludge Management
Union County currently disposes of aerobically stabilized liquid sludge by land
application. McKim & Creed analyzed options to use lime stabilization to produce a
"Class A" biosolid. For the near future, cis long as disposal sites are readily available,
Union County will continue ifs current program.
As a part of the County's plans to expand the Twelve Mile Creek plant, an analysis of
sludge management options was conducted. By reference, a copy of this report is
attached in Appendix E. The analysis supports continued reliance on land disposal
(beneficial reuse) of aerobically stabilized biosolids.
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SECTION 5.0 - USER CHARGES AND FINANCIAL CAPABILITY
5.1 User Charges
An analysis has been performed to evaluate the financial feasibility of the proposed
project. This was performed by Union County's Finance Department staff. A copy of the
analysis titled "Actual and Projected Results of Operations and Capital Improvements" is
attached in Appendix F. This analysis projected the performance of the Sewer Enterprise
Fund for the year ending in June, 2005 (assuming that the cost of improvements and
additional operations and maintenance costs are fully integrated into the annual
budgets) to the un-audited results for 2004. As stated in Note 5 on page 2, "Financing for
the Twelve Mile Creek Wastewater Treatment Plant Expansion individually has no impact
on current wastewater fees and rates."
5.2 Financial Feasibility
The US Bureau of Census reported the Union County Median Household Income at
$50,638 for the year 2000. The projected monthly sewer service bill for a typical family
usage of 5,000 gallons per month is projected to be $25.75. This is the equivalent of
about $309 per year, or 0.6 i % of the Median Household Income. The Twelve Mile Creek
expansion is not considered to be a "high cost" project, under Construction Grants and
Loans guidelines.
A copy of Union County's Water and Sewer Rates is also included in Appendix F:
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SECTION 6.0 - PROGRAM IMPLEMENTATION,
6.1 Proposed Action
A detailed analysis of growth trends in western Union County, particularly in the Twelve
Mile Creek sewer service area, confirms the need to provide additional wastewater
capacity by the year 2005. Projections illustrate that the available capacity of the
existing 2.5 mgd Twelve Mile Creek will be fully utilized by that time. To address this
critical need, Union County is proceeding to increase the treatment capacity from 2.5
mgd to 6.0 mgd in the Twelve Mile Creek sewer service area.
6.2 Recommended Facility Improvements
McKim & Creed has evaluated three options to provide the added 3.0 mgd of capacity.
The options consist of expanding the existing Twelve Mile Creek WWTP by constructing a
3.0 mgd land application facility, or by discharging up to 3.0 mgd into the Charlotte -
Mecklenburg Utilities system.
The 20-year capital cost of these options ranges from about $28.2 million to expand the
existing facility, to over $85.7 million for a land application system. The 20-year present
worth of these options is between $33.8 million and $78.9 million. Expansion of the
existing treatment facility is both the least expensive and most cost effective option. On
this basis, McKim & Creed has recommended the facility expansion, and has been
authorized by Union County to proceed with the necessary permitting and design
services_
6.3 Program Implementation
A further analysis of the selected alternative was performed to compare constructing the
additional 6.0 mgd of capacity in Iwo (2) 3.0 mgd phases, or a single 6.0 mgd expansion.
Details of this analysis are included in Appendix C, and summarized in Table 6.
Table 6
Phasing Analysis
Twelve Mile Creek WWTP Expansion
Option
20-Year Present Worth
Construct in two (2) 3.0 mgd phases
$33,758,000
Construct a single 6.0 mgd facility
$32,824,000
This analysis suggests that the present value of constructing the 20-year capacity in a
single phase is about $934,000 less than constructing the facility in two 3.0 mgd phases.
This cost differential of 2.8% is not considered statistically significant.
Union County should proceed to construct the facility in phases for the following reasons:
A. Funding: The projected $28.2 million cost to build in a single phase exceed the
funds that can be made available at this time.
Twelve Mile Creek WWTP 201 Facilities Plan
00771.0023
Page 29
November, 2004 Revision

B. Permits: The NPDES Permits Branch is unwilling to issue speculative limits for a total
flow in excess of 6.0 mgd.
C. The cost analysis does not provide justification sufficient to warrant the significant
up -front investment to construct in a single phase.
D. Constructing in phases more equitably shifts the capital cost impacts of future
expansion to future users.
Twelve Mile Creek WWTP 201 Facilities Plan
00771.0023
Page 30
November, 2004 Revision

SECTION 7.0 - ENVIRONMENTAL REVIEW
7.1 Environmental Assessment
An Environmental Assessment (E/A) document has been prepared for this project.
The E/A document is furnished separately in Appendix G.
7.2 Finding of No Significant Impact
The E/A has been distributed for review to the State Clearinghouse. On September 17,
2004, correspondence was received from Alex Marks, confirming that the E/A review is
complete and that a Finding of No Significant Impact (FONSI) was issued by the Division
of Water Quality on September 7, 2004.
The final documentation on the Clearinghouse review and the FONSI is attached in
Appendix G.
Twelve Mile Creek WWTP 201 Facilities Plan
00771.0023
Page 31
November, 2004 Revision

SECTION 8.0 - PUBLIC PARTICIPATION
(To be completed following the Public Hearing)
Twelve Mile Creek WWTP 201 Facilities Plan
00771.0023
Page 32
November, 2004 Revision

CROOKED/GOOSE
CLEAR CREEKS
SI'XM LE CREEK
M+sI+y " rwrtraaa 9 .O7
t.z1/4 Creek (6.25 NOD) ..
LANCASTER CO.
Figure 1
EXISTING SEWER SERVICE AREAS
Union County
STANLY CO,

EXISTING POTW
MONROE BYPASS
CORRIDOR
EXISTING TRUNK
SEWER
EXISTING SEWAGE
FORCE MAIN
A EXISTING SEWAGE
PUMP STATION
-- APPROXIMATE SEWERED
AREA IN WESTERN UNION
COUNTY
APPROXIMATE SEWERED
AREA IN TWELVE MILE CREEK
BASIN
APPROXIMATE SEWERED
AREA IN CROOKED CREEK
BASIN
Twelve Mile 1 Crooked Creek
Sewer Service Areas
ek
McKIlvi&CItEED
Figure 2

4"
EX STING POTW
MONROE BYPASS
CORRIDOR
DRAINAGE BASIN
BOUNDARY
SEWEREPTOR
SEWER
FORCEMAI N
EX{STING
PUMP STATION
Figure 3
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© HYDRAULIC PROFILE
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MILE CREEK
„
UNION CAROU
WASTEWATER TREATMENT FACILITY
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PROCESS SCHEMATIC/HYDRAULIC PROFILE/MASS

10.0
9,0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
2000
FIGURE 6
PROJECTED
WASTEWATER FLOW
2005
2010
YEAR
2015
2020
2025

601
*CC,
C
w
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tN44S
6,4
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Figure 7
General Soils Map

EXISTING POTW
PROPOSED POTW
EXISTING PUMP STATION
PROPOSED PUMP STATION
PROPOSED FORCEMAIN
EXISTING GRAVITY SEWER
EXISTING
SIX MILE
CREEK P
FIGURE 8
ALTERNATE 1
EXPAND EXISTING WWTP
1vFimvt&CRC
NQRTH
a

EXISTING POTW
MI PROPOSED POTW
EXISTING PUMP STATION
PROPOSED PUMP STATION
EXISTING
SIX MILE
CREEK P
PROPOSED FORCEMAIN
EXISTING GRAVITY SEWER
FIGURE 9
ALTERNATE 2
LAND APPLICATION
4.MIUM&cREED
PUMP TO LAND
APPLICAT6ON SITE

EXISTIN
SIX MILE
CREEK P
EXISTING POTW
PROPOSED POTW
EXISTING PUMP STATION
PROPOSED PUMP STATION
PROPOSED FORCEMAIN
EXISTING GRAVITY SEWER
FIGURE 10
ALTERNATE 3
PUMP TO CHARLOTTE
MECKLENBURG UTILITIES
McKINt&CRC
NORTH
0
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Twelve Mile Creek

Appendix A
Wastewater Flow Projections

Crooked Creek/Goose Creek
Population Served and Wastewater Flows
•
1999 Potential
1999 Actual
Sewer Basin
Population
Flow (mgd)
Population
Flow (mgd)
GC1 Goose Creek
6956
0.6956
1350
0.1350
GC2 North Fork Crooked Creek
3358 .
0.3358
3000
0.3000
GC3 South Fork Crooked Creek
4792
0.4792
4600
0.4600
GC4 Industrial Park Area
1747
0.1747 '
2250 -
.0.2250
5 Fairfield Plantation
0.1000
0.1000
SUBTOTAL:
11200
1.2200
Crooked Creek WWTP Base Flow
1.5000
North Fork Crooked Creek Diverted Flow
0.0000

- Crooked Creek/Goose Creek
Population Served and Wastewa•
•
2005 Potential
1999 - 2005 Growth
2005 Actual
Sewer Basin
Population
Flow (mgd)
Population
Flow (mgd)
Population
Flow (mgd)
GC1 Goose Creek
7915
0.7915
959
0.0959
2309
0.2309
GC2 North Fork Crooked Creek
7634
0.7634
4276
0.4276
7276
0.7276
GC3 South Fork Crooked Creek
5036
0.5036
244
0.0244
4844,
0.4844
GC4 Industrial Park Area •
3011
0.3011
1264
0.1264
3514
0.3514
5 • Fairfield Plantation
0.1000
.
SUBTOTAL:
17943
1.8943
Crooked Creek WWTP Base Flow
1.5000
North Fork Crooked Creek Diverted Fig .
0.3943

Crooked Creek/Goose Creek
Population Served and Wastewa•
2010 Potential
2005 - 2010 Growth
2010 Actual
Sewer Basin
Population
Flow (mgd)
Population .
Flow (mgd)
Population
Flow (mgd)
GC1 Goose Creek
8918
0.8918
1003
0.1003
3312
0.3312
GC2 North Fork Crooked Creek
11084
1.1084
3450
0.3450
10726
1.0726
GC3 South Fork Crooked Creek
6304
0.6304
1268
0.1268
6112 '
0.6112
GC4 Industrial Park Area
4597
, 0.4597
: 1586
0.1586
5100.
0.5100
5 Plantation
0.1000
SUBTOTAL:
25250
2.6250
Crooked Creek WWTPBase Flow
1.5000
Nnrfh Fork Crooked Creek Diverted FI.
1.1250

. Crooked Creek/Goose Creek
Population Served and Wastewa.
2020 Potential
2010 -2020 Growth
2020 Actual
Sewer Basin
Population
Flow (mgd)
Population
Flow (mgd)
Population
Flow (mgd)
GC1 Goose Creek
10922
1.0922
2004
0.2004
5316
0.5316
GC2 North Fork Crooked Creek
17980
1.7980
6896
0.6896
17622
1.7622
GC3 South Fork Crooked Creek
8866
0.8866
2562
0.2562
8674. '
0.8674
GC4 Industrial Park Area
' 7769
0.7769
3172
0.3172
8272
0.8272
5 Fairfield Plantation
0.1000
SUBTOTAL:
39884
- 4.0884
•
Crooked Creek WWTP Base Flow
4.5000 _
North Fork Crooked Creek Diverted Fi
- 0.0000 I

Twelve Mile Creek Service Area
Population Served and Wastewater Flows
Sewer Basin/Description
1999 Potential
1999 Actual
Population
Flow (mgd)
Population
Flow (mgd)
TMC 1
Upper West Fork TMC @ Beulah Ch Rd (1 school)
10953
1.0953
775 .
0.0775
TMC 2
Upper Price Mill Creek & Davis Mine Creek
3713
0.3713
130
0.0130
TMC.3
Culvert Branch (3 Schools)
1835
0.1835
250
0.0550
TMC 4
Lower Price Mill Creek (1 School)
828
0.0828
400
0.0500
TMC 5
Upper East Fork TMC @ Waxhaw Indian Trail Road
3534
0.3534
3240
0.3240
TMC 6
Mundy's Run
1347
0.1347
TMC 7
Middle West Fork TMC
751
0.0751
TMC 8
Middle East Fork TMC
740
0.074
135
0.0135
TMC 9
Rodgers Branch
402
0.0402
rMc 10
Waxhaw-Blythe Creek (two schools)
2943
0.2943
2800
0.3000
AMC 11
Little TMC 2751
0.2751
"MC 12
Creek
312
0.0312
100
0.0100
"MC 13
Mineral Springs
784
0.0784
Total Combined School Flow
0.0060
0.0600
'otal - Twelve Mite Creek'Dasin
30893
3.0953
7830 •
0.9030
forth Fork Crooked Creek Diverted Flow
'rojected Twelve Mile Creek VVWTP Flow
0.0000
0.9030

Twelve Mile Creek Service Area
Population Served and Wastewater Flows
Sewer Basin/Description
2005 Potential 1 1999 - 2005 Growth
2005 Actual
Population Flow (mgd) Population J Flow (mgd)
Population 1 Flow (mgd)
TMC 1
Upper West Fork TMC @ Beulah Ch Rd (1 school)
12789
1.2789
1836
0.1836
2611
0.2611
TMC 2
Upper Price Mill Creek & Davis Mine Creek
5133
0.5133
1420
0.1420
1550
0.1550
TMC 3
Culvert Branch (3 Schools)
3500
0.3500
1665
0.1665
1915
0.1915
TMC 4
Lower Price Mill Creek (1 School)
1553
0.1553
725
0.0725
1125
0.1125
TMC 5
Upper East Fork TMC @ Waxhaw Indian Trail Road
6590
0.6590
3056
0.3056
6296
0.6296
TMC 6
Mundys Run
2172
0.2172
825
0.0825
825
0.0825
TMC 7
Middle West Fork TMC
1308
0.1308
557 0.0557
557
• 0.0557
TMC 8
Middle East Fork TMC
1452
0.1452
712 0.0712
847
0.0847
TMC 9
Rodgers Branch
840
0.0840
438 0.0438
438
0.0438
TMC 10
Waxhaw-Blythe Creek (two schools)
4743
0.4743
1800 0.1800
4600
0.4600.
TMC 11
Little TMC
4658
0.4658
1
1907 0.1907
f
1907
0.1907
TMC 12
Creek
693
0.0693
381 0.0381
481
0.0481
TMC 13
Mineral Springs
1380
0.1380
596 0.0596
596
0.0596
Total Combined School Flow
0.0600
0.0600
0.0600
total - Twelve Mile Creek Basin
46808
4.7408
15915 1.6515
23745
2.4345
North Fork Crooked Creek Diverted Flow
Projected Twelve Mile Creek VVWTP Flow
0.3943
2.8288

Twelve Mile Creek Service Area
Population Served and Wastewater Flows
Sewer Basin/Description •
2010Potential
2005 - 2010 Growth 1 2010 Actual
Population 1 Flow (mgd)
Population Flow (mgd) Population 'Flow (mgd)
TMC 1
Upper West Fork TMC @ Beulah Ch Rd (1 school)
14625
1.4625
1836
.0.1836
4447
0.4447
TMC 2
Upper Price Mill Creek & Davis Mine Creek
6553
0.6553
1420
0.142
2970
0.2970
TMC 3
Culvert Branch (3 Schools)
5164
0.5164
1665
0.16645
3579
0.3579
TMC 4
Lower Price Mill Creek (1 School)
2277
0.2277
725
0.07245
1849
0.1849
TMC 5
Upper East Fork TMC @ Waxhaw Indian Trail Road
9646
0.9646
3056
0.3056
9352
0.9352
TMC 6
Mundy's Run
2996
0.2996
825
0.08245
1649
0.1649
TMC 7
Middle West Fork TMC
1865
0.1865
557
0.0557
1114
0.1.114
TMC 8
Middle East Fork TMC
2163
0.2163
712
0.07115
1558
0.1558
TMC 9
Rodgers Branch
1278
0.1278
438
0.0438
876'
0.0876
TMC 10
Waxhaw-Blythe Creek (two schools)
6542
0.6542
1800
0.17995
6399
0.6399"
TMC 11
Lithe TMC
6565
0.6565
1907
0.1907
3814
0.3814
TMC 12
Creek
1073
0.1073
381
0.03805
861'
0.0861
rMC 13
Mineral Springs
1976
0.1976
596
0.0596
1192
0.1192
Total Combined School Flow
0.0600
0.0600
0.0600
total - Twelve Mile Creek Basin
62723
6.3323
15915
1.6515
39660
4.0260 •
forth Fork Crooked Creek Diverted Flow
projected Twelve Mile Creek WWTP Flow
1.1250
5.1510

Twelve.MYlile Creek Service Area •
Population Served and Wastewater Flows
Sewer Basin/Description
2020 Potential
2010 -2020 Growth
2020 Actual
Population J Flow (mgd)
Population j Flow (mgd)
Population
Flow (mgd)
TMC 1
Upper West Fork TMC © Beulah Ch Rd (1 school)
18232
1.8232
3607
0.3607
8054
0.8054
TMC 2
Upper Price Mill Creek & Davis Mine Creek
6983
0.6983
430
0.0430
3400
• 0.3400
TMC 3
Culvert Branch (3 Schools)
. 5802
0.5002
638
0.0638
4217
0.4217
TMC 4
Lower Price Mill Creek (1 School)
4120
0.4120
1643
0.184.3
3692
0.3692
TMC 5
Upper East Fork TMC © Waxhaw Indian Trail Road
17252
1.7252
7606
0.7606
16958
1.6958
TMC 6
Mundy's Run
5078
0.5078
2082
• 0.2082
3731
0.3731
TMC 7
Middle West Fork TMC
2790
. 0.2790
925
0.0925
2039
0.2039
TMC 8
Middle East Fork TMC
3119
0.3119
956
0.0956
2514
0.2514
TMC 9
Rodgers Branch
1370
0.1370
92
0.0092
968
0.0968
TMC 10
Waxhaw-Blythe Creek (two schools)
10152
1.0152
3610
' 0.3610
10009
1.0009'
TMC 11 Little TMC
11491
1.1491
4926
0.4926
8740
0.8740
TMC 12
Creek
1103
0.1103
30
0.0030
891
0.0891
TMC 13
Mineral Springs
3560
0.3560
1584
0.1584
2776
0.2776
Total Combined School Flow
0.0600
0.0600
0.0600
Total - Twelve Mile Creek Basin
91052
9.1662
28329
2.8929
67989
6.8589
North'Fork Crooked Creek Diverted Flow
Projected Twelve Mile Creek WWTP Flow
0.0000
6.8589

Appendix B
Project Site Data

1716z>Z3
United States Department of the Interior
U.S. GEOLOGICAL SURVEY
3916 Sunset Ridge Road
Raleigh, North Carolina 27607 •
July 15, 2002
Mr. WS. Riddick, Jr., PE, Senior Project Manager
McKim & Creed Engineers
2300 Sardis Road North, Suite A
Charlotte, North Carolina 28277
Dear Mr. Riddick:
In response to your request for Iow-flow data, the U.S. Geological Survey (USGS) provides the following
low -flow characteristics for the continuous -record gaging station at Twelve Mile Creek near Waxhaw, NC
(station id 02146900, drainage area 76.5 mi2). The low -flow data that are provided on the attached sheet
have been computed based on techniques used by the USGS for assessing the low -flow characteristics at
continuous -record gaging stations having 10 or more years of record. Please note that the flow estimates
only account for the effects of any upstream diversions or regulation that have occurred during the period
of record at the gaging station.
The gaging station on Twelve Mile Creek has been in operation since October 1960. The available full
period of record through the most recent water year of published data (2001) was used in the analyses. The
7-day, 10-year (7Q10) low -flow discharge based on this period is 0.10 ft3/s, or 0.0013 ft3/s/mi2 of drainage
area (termed as the 7Q10 yield). A 7Q10 yield of this magnitude indicates fairly low potentials for sustained
base flows relative to other areas in parts of North Carolina. The basin upstream of the gaging station is
underlain by the geologic units of the Carolina SIate Belt, which has historically been correlated with rela-
tively low potentials for sustained bases flows at many streams within this belt. The 30-day, 2-year (30Q2)
low -flow discharge based on this period is 3.2 ft3/s, or a 30Q2 yield of 0.0412 ft3/slrni2.
You identified the actual Iocation of the discharge point as being approximately 2,500 feet downstream of
the gaging station. An examination of the topographical quad map showing the location of the gaging sta-
tion and the downstreamreachindicates that no tributaries enter into Twelve Mile Creek between the station
and the discharge point. Thus, the Iow-flow characteristics at the gaging station can be considered applica-
ble to the discharge point.
A charge for accessing and processing information has been assessed to partially offset these costs. Your
requested data and an invoice covering processing costs for these data are enclosed. Please forward the
original bill with your check to the U.S. Geological Survey, 12201 Sunrise Valley Drive, MS 27I, Reston,
Virginia 20192.
These data are preliminary and subject to revision pending approval for publication by the Director of the
U.S. Geological Survey, and are made available through our cooperative program of water -resources inves-
tigations with the North Carolina Department of Environment and Natural Resources.
If you have any questions regarding this information, please contact us at [phone].
Enclosures
•
Sincerely,
J. Curtis Weaver
Hydrologist

SUMMARY OF LOW -FLOW ESTIMATES IN RESPONSE TO REQUEST
REQUEST NO: . 91613 SITE NO: 01 DATE: 07/15/2002
SOURCE: - Consulting ACTION: • Existing
STATION NUMBER: 02146900 STATION TYPE: Continuous -record (01)
STATION NAME: Twelve Mile Creek near Waxhaw. NC
LOCATION: At NC Highway 16, and 2.5 miles north of Waxhaw
LATITUDE: 35°57'08" LONGITUDE: 80°45'21"
QUANDRANGLE NAME AND NUMBER: Catawba NE (H-15-NE1
COUNTY CODE: Union (1791 STATE CODE: NC f371 DISTRICT CODE: NC 1371
HYDROLOGIC UNIT CODE: 03050103 ENR BASIN CODE: 03-08-38
DRAINAGE AREA: 76.5 • mi2
Flow statistics as follows:
AVERAGE FLOW: Estimated using 0.95 ft3/s/mi2 72.7 ft3ls see note L./51
ANNUAL 7Q10 MINIMUM FLOW: 0.0013 ft3/s/mi2 0.1 ft3/s see note U
ANNUAL 30Q2 MINIMUM FLOW: 0.0412 ft3/s/mi2 3.2 ft3/s see note L A -1
WINTER 7Q10 MINIMUM FLOW 0.0200 ft3/s/mi2 1.5 ft3/s see note L Al
ANNUAL 7Q2 MINIMUM FLOW: 0.0183 ft3/s/mi2 1.4 ft3/s see note LA
NOTES:
[A] Estimate is based on records collected at or near the request site.
[B] Estimate is based entirely on runoff characteristics observed at nearby streams.
(C] Estimate based on procedures given in USGS Water Supply Paper 2403 "Low -flow Characteristics
of Streams in North Carolina" (Giese and Mason, 1993).
(D] Estimate based on procedures given in USGS Water Supply Paper 2403 and in conjunction with
streamflow records collected at or near the request site.
[E] See remarks.
These data are considered provisional and subject to revision pending approval by the Director, USGS.
REMARKS:
• Low -flow estimates based on discharge records collected at gaging station during 1961-2000 climatic years
(12-month period from April 1 through March 31 and designated by the year in which the period begins,
used in Iow-flow analyses at continuous -record gaging stations)
• • Requested by Mr. Sid Riddick, McKim & Creed Engineers
ENTERED BY: JCW FEE CHARGED: $ 150

U C PUBLIC WORKS 7042984232
State of North Carolina
Department of Environment
and Natural Resources
Division of Water Quality
Micheal F. Easley, Governor
William G. Ross, Jr., Secretary
Alan W. Klimek, P.E., Director
•
- June 14, 2002
Mr. Son C. Dyer, P.E., Director
Union County Public Works Department
400 North Church St.
Monroe, North Carolina 28112-4804
Dear Mr.•Dyer:
06/22/22 06:13pm P. 002
77lOo3CSC
A4751111:A
NCDENR
•
Subject: Union County -Twelve Mile Creek WWTP
Speculative Limits for Expansion
NPDES Permit No. NC0085359
Union County
.This letter is in response to the request for speculative effluent limits for proposed expansions of
the subject WWTP. Wastewater flows of 6.0, 9.0, and 12.0 MGD were targeted for expansion of
the Twelve Mile Creek WWTP into Twelve Mile Creek in the Catawba River Basin. After .
consultation with the permittee, it has been••determined that the staff of the NPDES will only
provide speculative effluent limits'for16:0 MGD at this time:: These limits should be considered
very preliminary, as there are a numb
er of pending actions a nd.communications that may
influence your project. Twelve Mile Creek eventually flows into the Catawba River after
crossing the South Carolina state line. Any fmalized permit will be subject to review and
scrutiny by that State, in addition to the U.S. Environmental Protection Agency.
It should be noted that expanding facilities,: involving.an expenditure of public funds or use of
public- (state) lands, will be required to prepare a n'Environmental Assessment (EA) when
•wasteflows exceed or equal 0.5 MGD. If the EA demonstrates that the project may result in a
significant adverse effecton the quality.of the enviz'onment,'an Enviroiunental Impact Statement
(EIS) is required: DWQ will not accept a permit application for aproject requiring an EA or EIS
until: (1) the document has been approved by the Department of Environment and Natural
Resources and, (2) a Finding.of Flo Significant Impact (FONSI) has been sent to the State
Clearinghouse for review and comment or an EIS has.been approved. The Division of Water
Quality's' Planning Branch can provide further information regarding the requirements of the
N.C. Environmental Policy :Act: `Please contact Todd Kennedy of the'DWQ Planning Branch at
[phone] 'ext. 555 if youe a ue have 9 f stions oil thissubject
: '
1617 Mail Service Center, Raleigh, North Carolina.27699-1617 Telephone [phone] FAX.[phone]
An Equal Opportunity Affirmative Action Employer. Internet: http:llh2o.enr.state.nc.us!

U C PUBLIC WORKS 7042864232 06/20/22 26:13pm P. 003
Twelve Mile Creek WWTP Speculative Limits
Page 2
Be advised that providing speculative limits do not guarantee that the Division will issue an
NPDES permit to discharge treated wastewater. Union County will also be required to complete
an Engineering Alternatives Analysis (EAA) that must be submitted with the application for a
flow expansion of the NPDES permit. The EAA should contain a defensible justification for the
proposed expansion and an analysis of potential alternatives, which should include a thorough
evaluation of non -discharge alternatives. Nondischarge alternatives, such as spray irrigation,
water conservation, or reuse, are considered to be environmentally preferable to a surface water
discharge. In accordance with the North Carolina General Statutes, the practicable waste
treatment and disposal alternative with the least adverse impact on environment is required to be
implemented.
This segment of the Twelve Mile Creek has a stream classification of C. The best usage of these
waters is aquatic life propagation and maintenance of biological integrity (including fishing, and
fish), wildlife, secondary recreation, and agriculture. Using information available at this current
time, the discharge point has an estimated drainage area of 76.8 square miles, with an average
flow of 69 cfs, a summer 7Q10 flow of 0.0 cfs, a winter 7Q10 flow of 1.5 cfs and a 30Q2 flow of
2.5 cfs. Please be advised that these .flows were estimated ,by. DWQ, however-it.is,preferable
the County request actual flow estimations from the United States G.eological Survey to ensure
accuracy.
As discussed in the April 25, 2002 meeting, it is recommended that Union County perform an
extensive synoptic study of dissolved oxygen levels in Twelve Mile Creek. Instream water _
quality data indicated that there were dissolved oxygen levels below the 5.0 mg/I standard both
above and below the Twelve Mile Creek WWTP discharge. 'There were data that showed
occasionally the downstream DO standard contravention occurred immediately downstream of
the WWTP and then sometimes occurred in a segment of Twelve Mile Creek located in South
Carolina. The collection of DO data should help determine whether the low instream DO values
can be attributed to the discharge from Twelve Mile Creek WWTP or other environmental
factors. Union County should conduct sampling of temperature and dissolved oxygen upstream
of the WWTP and downstream of all highway and/or bridge crossings, including the South
Carolina portion of Twelve Mile Creek. Sampling should be three times per week during the
summer months (April through October) to provide data during the critical low flow period.
During the winter months (November through March) instream sampling could be done weekly.
The results of this study should be included as part of the SEPA documentation regarding the
impact of the Twelve Mile Creek WW1P on water quality in the receiving stream.
Based on available information, the tentative effluent limits for oxygen -consuming constituents
of the Union County — Twelve Mile WWTP discharge at the flow of 6.0 MGD are included on
the attached effluent sheet. Upon formal permit application, if there is an industrial wastewater
constituency, an evaluation of limits and monitoring requirements for metals and other toxicants
will be addressed at that time. Based on an agreement with the State of South Carolina, North
Carolina has agreed to apply a mass limit equivalent to 1.0 mg/I of total phosphorus at the
existing permitted flow of 2.5 MGD. Compliance with the limit will be judged as a rolling
annual average. Union County should also prepare for the impending phosphorus total maximum
daily load (TMDL) from South Carolina within 3-5 years. This phosphorus TDML could result
in limits much lower than proposed here.

U C PUBLIC WORKS 7042984232 OS/20/02 OS:1Spm P. 004
Twelve Mile Creek WWTP Speculative Limits
Page 3
It is recommended that the facility initiate quarterly effluent monitoring for copper and zinc.
During an investigation into a recent whole effluent toxicity test failures, DWQ was unable to
complete the evaluation because this discharge does not monitor for copper and zinc. DWQ has
found that copper and/or zinc are often significant causative factors in whole effluent toxicity.
failures. The inclusion of monitoring for these parameters will provide DWQ with the data '
required evaluating if copper and zinc are potential sources of toxicity.
The Division of Water Quality is requiring chlorine limits for all new or expanding dischargers
'proposing the use of chlorine for disinfection. Dechlorination or an alternate form of
disinfection, such as ultraviolet radiation, should allow the facility to comply with this
requirement.
Final NPDES effluent limitations will be determined after a permit application has beep
submitted to the Division. If there are any additional questions concerning this matter, please
feel free to contact Jackie Nowell of my staff at [phone] ext. 512.
Respectfully,
David A. Goodrich .
NPDES Unit Supervisor
cc: Mooresville Regional Office/Rex Gleason
Bobby Blowe, Construction Grants
Central Files
NPDES Permit File
Jeff deBessonet, Bureau of Water DHEC, 2600 Bull St., Columbia SC 29201

U C' PUBLIC WORKS 7042564232 06/2.c^./22 0B:13pm F. 005
Twelve Mile Creek WWTP Speculative Limits
Page 4
A. SPECULATIVE EFFLUENT LTMITATIONS AND MONITORING
REQUIREMENTS - UNION CO. — TWELVE 1VIILE CREEK WWTP
' 3 ;x r 4: ., ,
,;1- ?--etvmoil ii,al1 vap:'- '+emu c:i " 1E ..
7.. ..: M 1 Khoo . M ?
'r_(..1'•',�AzTr.sc�
.!�'
`�"F.�.�s,
Y x y
�.x'. -I[ti J�=. r-mil-:i!F lnaeiil
-vi ,. a:rs
�'tY 5'i•;k
rr �6�a
.—•r7wr��n:,�.r� ��
� ��•�.+ '*fir
F.zh"C� �
�''ii+.:
�x -
�' F'ls ."cif i:Ta�./
12
�" sA .i.. 1 '�.?;
�'
='1�+
�".']
RIIL �t?^
.. � "��ss
:�r�� '
L`�=� n� ��
-10 �r
'Igt ►1 •-
: r ,�i.n..•,;st�' �� eaiLy;�',�•. y`__:i;e.
}' ���'J�'j�� ��_ '���.'�`
L ieaF.-_.r zi:.a�
y�LL.�'1"!U,�;T•T, `- �'�'kA4Tr'-
'�I' �_ r
�1 i aw 3'
.� }+��F t_
�i= .. - ..T
� _
Flow
6.0 MGD
Continuous
Recording
influent or Effluent
BOD, 5-day, 20°C2
(April 1— October 31)
5.0 mg/L
7.5 mg/L
Daily
Composite
influent, Effluent
DOD, 5-day, 20°C2
(November 1— March
30)
10.0 mg/L
15.0 mg/L
Daily '
Composite
.
Influent, Effluent '
Total Suspended
Residue 2
30.0 mg/L
45.0 mg/L .
Daily
.
Composite
Influent, Effluent
. .
_
NH3 as N (April 1-
October 31)
1.0 mg/L
Daily . '
Composite
Effluent
NH3 as N (November 1
—March30)
2.0 mg/L
-
.
Daily
Composite
r
Effluent
Dissolved 0xygen3
-
Daily
Grab
Effluent, Upstream,
Downstream
' Fecal Coliform
(geometric mean) -
2001100
mi
4001100
ml
Daily
Grab :
Effluent , Upstream,
Downstream
pH4
. Daily
Grab
Effluent
Conductivity
•
` .
Daily
Grab
Effluent -
Total Phosphorus
Monthly Average: 41.7 lbslday
12 Month Average: 20.9 lbslday
Monthly
Composite
Effluent
Total Nitrogen
(NO2+NO3+TKN)
-
Monthly
Composite
Effluent
Chronic Toxicity5
Quarterly
Composite
Effluent
Total Copper
Quarterly
Composite
Effluent
Total Zinc •
.
Quarterly .
• Composite
Effluent _
Temperature, °C
•
Weekly
Grab
Effluent , Upstream,
Downstream
Notes:
1. Influent, Effluent, Upstream 50 feet above the outfall; Downstream sampling points Dl+D2; 01-- One
con
fluence mile below the outfall, before with the first tributary; D2 - Downstream at NCSR
1301
2. The monthly average effluent BOD5 and Total Suspended Residue concentrations shall not exceed
15% of the respective influent value (85% removal). •
3. The daily dissolved oxygen effluent concentration shall not be Iess than 6.0 rng/l.
4. The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units.
5. Chronic Toxicity (Ceriodaphnia) P/F at 90%; February, May, August, and November.

Appendix C
Cost Estimates
= Present Worth Summary
• Phasing Analysis

Present Worth Summary

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
ALTERNATE 1 - EXPAND PLANT
ALTERNATE 2 - LAND APPLICATION
ALTERNATE 3 - PUMP TO CMUD
PHASE 1
CAPITAL
$12,289,000
$70,755,000
$27,585,000
PHASE 2
CAPITAL
PRESENT WORTH
$8,762,000
$8,241,000
$13,557,000
O&M
2004
$647,500
$820,000
$931,000
O&M
2014
$1,535,500
$1,845,000
O&M
2024
$2,867,500
$2,136,000
$2,336,000 $3,077,000
O&M
PRESENT WORTH
$16,232,000
$17,317,000
$22,158,000
SALVAGE
VALUE
PRESENT WORTH
-$3,525,000
-$17,416,000
-$9,599,000
TOTAL
PRESENT WORTH
$33,758,000
$78,897,000
$53,701,000

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
CAPITAL COST
2004
2014
2024
ALTERNATE 1 - EXPAND PLANT
PHASE 1-EXPAND PLANT TO 6.0 MGD
$12,289,000
PHASE 2-EXPAND PLANT TO 9.0 MGD
$15,877,000
ALTERNATE 2 - LAND APPLICATION
PHASE 1 - BUILD 3 MGD FACILITY
$70,755,000
PHASE 2 - EXPAND TO 6.0 MGD
$14,934,000
ALTERNATE 3 - PUMP TO CMUD
PHASE 1
CONSTRUCT FM & PIS
$11,059,000
CMUD CAPITAL CHARGES
$16,526,000
TOTAL
$27,585,000
PHASE 2
CONSTRUCT PIS
$828,000
CMUD CAPITAL CHARGES
$23,739,000
TOTAL
$24,567,000

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
OPINION OF PROBABLE COST
ALTERNATIVE 1 - PHASE 1
EXPAND TREATMENT PLANT TO 6.0 MGD
YEAR 2004
ITEM
DESCRIPTION
HEADWORKS W/ ODOR
CONTROL
UNIT
UPGRADE INFLUENT PS
OXIDATION DITCHES ILS: `:_= ; •".I
CLARIFIERS
RECYCLE/WASTE PUMP ILS2
1 MG DIGESTER W/
BLOWERS
FILTERS & AIR COMP.
UV DISINFECTION
BLOW BUILDING
ELECTRICAL
SITE WORK PIPING
ESTIMATED
QUANTITY
1
1
1
UNIT PRICE
:I4$2;000,000.;
2 ($750Q001
1
1
1
1
LS,_V _s . w�: 1
400 0001
yt $i1'o00000
_•u'$750;0001
► .1$605;0001
I $50;0001
T .. 2$.tO000001
$1;,500 O0.01
TOTAL PRICE
$1,000,000
$600,000
$2,000,000
$1,500,000
$400,000
$1,000,000
$750,000
$605,000
$50,000
• $1,000,000
$1,500,000
SALVAGE VALUE
N/A $500,000
NIA $0
$1,500,000
$1,125,000
N/A $0
N/A $0
N/A $375,000
N/A $302,500
$25,000
N/A $500,000
N/A $750,000
TOTAL $5,077,500
SUB -TOTAL
$8,905,000
CONTINGENCY - 20%
$1,781,000
TOTAL CONST. COST
$10,686,000
ENGR. & ADMIN. - 15%
$1,602,900
PROJECT TOTAL
ENGINEERING NEWS RECORD CCI = 6589
$12,289,000

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
OPINION OF PROBABLE COST
ALTERNATIVE 1 - PHASE 2
EXPAND TREATMENT PLANT TO 9.0 MGD
YEAR 2014
ITEM
DESCRIPTION
NEW PARALLEL INFLUENT I.
PUMP STATION
UNIT
ADDITIONAL SCREENING
ADDITIONAL GRIT REMOVAL ILSr' ."''
OXIDATION DITCHES
CLARIFIERS
RECYCLE/WASTE PUMP
1.0 MG AEROBIC DIGESTER {,.
W/ BLOWERS BLS.. °a. _.j 4,
FILTERS
UV DISINFECTION �LSs r
ELECTRICAL
SITE WORK PIPING LSE'
NEW INPLANT PUMP
STATION
SUB —TOTAL
ESTIMATED
QUANTITY
1
1
1
1
2
1
UNIT PRICE
'$1 000 &O
.., $250;0001
;$500000.
. $2 000 000
. $750 0001
$400QQ0.
1 $�i00Q;`000.
2
1
1
1
1
CONTINGENCY - 20%
TOTAL CONST. COST
ENGR. & ADMIN. —15%
PROJECT TOTAL
ENGINEERING NEWS RECORD CCI = 6589
.$750;000I
:$605 000
`$1;000;000.1
_ ._1$11;500 000J
`$250000; $250,000
TOTAL PRICE
$1,000,000
$250,000
$500,000
$2,000,000
$1,500,000
$400,000
1000000
$1,500,000
$605,000
$1,000,000
$1 ,500,000
$11,505,000
$2,301,000
$13,806,000
$2,070,900
$15,877,000
SALVAGE VALUE
$375,000
$125,000
$250,000
$1,500,000
$1,125,000
$100,000
$625,000
$750,000
$302,500
$500,000
$750,000
$93,750
TOTAL $6,496,250

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
OPINION OF PROBABLE COST
ALTERNATIVE 2 - PHASE 1
3.0 MGD LAND APPLICATION PLANT
ITEM
DESCRIPTION
UNIT
ESTIMATED
QUANTITY
UNIT PRICE
TOTAL PRICE
SALVAGE VALUE
HEADWORKS W/ ODOR
CONTROL tL;
C:,000;0001
$500,000 •
INFLUENT PUMP STATION ILS
$500,000i'
,$500 000
$187,500
FORCE MAIN 30" DIA. fLF
52;800.-
$15T
$7,920,000
$6,336,000
SPRAY FIELD PIPING
10,0;
$3,025
$3,0250000'',
$1,512,500
EROSION CONTROL
LS.
-• $175,000
'$175,000'
N/A $0
LAGOON -145 AC
ILS
145 ' "
$38,381 I
$5,565245
$2,782,623
FENCING
ELF .
12;500
$'1.5t;.
$187500'...
N/A $0
LAB CONTROL BUILDING ES
$390;8306.
$390830
N/A $0
ELECTRICAL
BLS',
"- $363,0
-$363000
NIA $0
EFF. PUMPING
gLS
:_.$363,000
$363000.'..
N/A $0
MONITORING WELLS
CLEARING
BLS
1
2,200
; $1'45:,000 ..
$250!'
$145,000I
$550,000;
NIA $0
N/A $0
SUB -TOTAL
$20;184,570
CONTINGENCY - 20%
$4 036915
TOTAL CONST. COST
$241,221,490
ENGR. & ADMIN. - 15%
$3,633 224
SUB -TOTAL
;$27 854. , 714
IRRIGATION SITE - 4000 AC @ $ 10,0001AC
$4.0 000000'
$40,000,000
LAGOON SITE - 290 AC @ $ 10,000/AC
$2,900;000
$2,900,000
PROJECT TOTAL
$70...,755,000`
TOTAL $54,218,623
Source: EPA MANUAL "COST OF LAND TREATMENT SYSTEM", 430/9-75-003-1979

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
OPINION OF PROBABLE COST
ALTERNATIVE 2 - PHASE II
6.0 MGD LAND APPLICATION PLANT
ITEM
DESCRIPTION
UNIT
ESTIMATED
QUANTITY
UNIT PRICE
TOTAL PRICE
SALVAGE VALUE
INFLUENT PUMP STATION 4'
MODIFICATIONS 1LS_ ..
FORCE MAIN 30" DIA.
$500,000'
$50;0 000
$187,500
N/A $0
SPRAY FIELD PIPING ;AC.,,
.$3,025;000
N/A $0
EROSION CONTROL
$175,0001
$175Q00;
N/A $0
LAGOON - TO 290 AC
11LS. _.
:145.
$38;381
$5565245:
N/A $2,782,623
FENCING
;LF_.
9000
$15
`$135,000
NIA $0
LAB CONTROL BUILDING ,LS
$0,
$0
N/A $0
ELECTRICAL
EFF. PUMPING
BLS
BLS
%$363,000.:
$363,000';
$363 000,
$363 000'
N/A $0
NIA $0
MONITORING WELLS
k$145';000�
.$145 000'.
NIA $0
CLEARING
AC
2200
$250E
$550;000
N/A $0
SUB -TOTAL
CONTINGENCY - 20%
$2,164;249.
TOTAL CONST. COST
$12,985,494'
ENGR. & ADMIN. - 15%
$1,947 8241
PROJECT TOTAL
$14,934 000
TOTAL $2,970,123
Source: EPA MANUAL "COST OF LAND TREATMENT SYSTEM", 430/9-75-003-1979

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
OPINION OFPROBABLE COST
ALTERNATIVE 3 - PHASE 1
3.0 MGD TREATMENT BY CMUD
YEAR 2004
ITEM
DESCRIPTION
UNIT
ESTIMATED
QUANTITY
UNIT PRICE
TOTAL PRICE
SALVAGE VALUE
5200 GPM PUMP STATION
L'S`..a -=w-:f .1 1
I. _ -. - -'" :$5000001
$500,000
$187,500
HEADWORKS W/ ODOR
CONTROL
LS '.- . ;�
1
,. $1,000;000J
$1,000,000
$500,000
30" FORCE MAIN
LF _g ;;;, ;,f;1_ 34,000
1u , ., . r,; $1501
$5,100,000
$4,080,000
36" GRAVITY SEWER
LE- . r; '_-:.:.11 5,000
H :-:_;.:=;:a -- �'$1801
$900,000
$720,000
30" BORE
LF ', ', :,`.°r _ .I 250
1" in- ' ,- f _ s$4001
$100,000
N/A
$0
4' MANHOLES
EA - •--a' F;:: ' 1 25
r:='.w -.. _^' .-.,7$22001
$55,000
$44,000
INTERCONNECTIONS
EA ..k-.1 1
1• ;$6,'i'00I
$6,100
N/A
$0
EROSION CONTROL
LSC; ' _ , e , -;; =:.1 1
1:.-_ ' °1,1-., , , .-..:i$58 6'001
$58,600
WA
$0
SEEDING & CLEANUP
LS' •-', -..V._1 1
1..._.::11-�ti'_.•.:-$1'8;3001
$18,300
WA
$0
ELECTRICAL
LSD,'.. _.. ,:,:_ J 1
1:,..„....__ _ _ $275;0001
$275,000
N/A
$0
SUB -TOTAL
$6,013,000
CONTINGENCY - 20%
$1,603,000
TOTAL CONST. COST
$9,616,000
ENGR. & ADMIN. - 15%
$1,443,000
SUB -TOTAL
$11,059,000
PROJECT TOTAL
$11,059,000•
CMUD CAPACITY CHARGES
*COST INFORMATION OBTAINED FROM CMUD
SIX MILE CREEK INTER/ PUMP STATION 3.0 MGD @
$1,765,000
$5,295,000
$4,183,050
McALPINE CREEK W WTP(2.0 MGD)
a) BASE CAPACITY 2.0 MGD ©
b) MODERNIZATION RELIABILITY 2.0 MGD ©
c) McALPINE CREEK WWTP(1.0 MGD)
$1,050,000
$1,491,500
$2,100,000
$2,983,000
$6,148,000
$1,575,000
$2,237,250
SUB -TOTAL - CMUD CAPITAL CARGES
TOTAL PHASE I CAPITAL COST
$16,526,000
$27,585,000
TOTAL SV $13,526,800

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
OPINION OF PROBABLE COST
ALTERNATIVE 3 - PHASE 2
3.0 MGD TREATMENT BY CMUD
YEAR 2014
_
.
ITEM
DESCRIPTION
UNIT
ESTIMATED
QUANTITY
UNIT PRICE
TOTAL PRICE
SALVAGE VALUE
30" FORCE MAIN LFk:,", 4 :4 0
r; ,. Yd �;. ' $150
$0
N/A
$0
12,150 GPM PUMP STATION iLSi ,: ' r : '1
1
-iqJZxs> :°$50000.01
$500,000
$187,500
36" GRAVITY SEWER ILF-,�-� t6'41'?,_
0
'345W16.i , rywf:„0$f801
$0
N/A
$0
30" BORE LF %% ,;;1
0
1 r , -: '.. ; *,¢a $'4.001
$0
N/A
$0
4' MANHOLES [EAf AT. ? w'l
0
Li ,z{ yZH"S $2 2001
$0
N/A
$0
INTERCONNECTIONS FEAR-.,
0
6:, ' aggirl$6.X001
$0
N/A
$0
EROSION CONTROL ILS+ :..:,7-1x3:
0
I<;� 3rs ;i5 14$5B6001
$0
N/A
$0
SEEDING & CLEANUP ILS
0
', 0 V.$ ,8;3.001
' $0
N/A
$0
ELECTRICAL BLSt .. JJ
1
- ; , i.$1`00 0001
' $100,000
N/A
$0
SUB -TOTAL
.$600,000
CONTINGENCY - 20%
$120,000
TOTAL CONST. COST
$720,000
ENGR. & ADMIN. - 15%
$108,000
SUB -TOTAL
$828,000
PROJECT TOTAL
$828,000
CMUD CAPACITY CHARGES
*COST INFORMATION OBTAINED FROM CMUD
SIX MILE CREEK INTER/ PUMP STATION 3.0 MGD @
$1,765,000
$5,295,000
$3,971,250
McALPINE CREEK WWTP 3xCMUD @
$6,148,000
$18,444,000
$13,833,000
SUB -TOTAL - CMUD CAPITAL CARGES
TOTAL PHASE I CAPITAL COST
$23,739,000
$24,567,000
TOTAL
$17,991,750

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
PRESENT WORTH ANALYSIS
EXPAND TREATMENT PLANT : ALTERNATE 1
DISCOUNT RATE 6.125%
TOTAL COST
PRESENT WORTH
PHASE l - 2004
$12,289,000
$12,289,000
PHASE II - 2014
$15,877,000
$8,762,000
O&M 2004
$647,500
O&M 2014
$1,535,500
O&M 2024
•
$2,867,500
O&M TOTAL
$16,232,000
SUB -TOTAL
$37,283,000
SALVAGE VALUE
$11,573,750
$3,525,000
$33,758,000
O&M PW CALCS
YEAR 1
$647,500
YEAR 10
$1,535,500
YEAR 20
$2,867,500
GRADIENT YR 1-10
$98,667
GRADIENT YR 10-20
$148,000
PW YR 1-10
$7;634,205
PW YR 10-20
$15,579,752
PW BACK TO YEAR 1
$8,597,724
TOTAL
$16,231,929

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
PRESENT WORTH ANALYSIS
LAND APPLICATION - ALTERNATE 2
DISCOUNT RATE 6.125%
TOTAL COST 1 'PRESENT WORTH
PHASE 1- 2004
$70,755,000
$70,755,000
PHASE II - 2014
$14,934,000
$8,241,000
O&M 2004
$820,000
O&M 2014
$1,845,000
O&M 2024
$2,136,000
O&M TOTAL
$17,317,000
SUB -TOTAL
$96,313,000
SALVAGE VALUE
$57,188,745
$17,416,000
TOTAL
$78,897,000
O&M Present Worth CALCS
YEAR 1
$820,000
YEAR 10
$1,845,000
YEAR 20
$2,136, 000
GRADIENT YR 1-10
$113,889
GRADIENT YR 10-20
$32,333
PW YR 1-10
$9,343,227
PW YR 10-20
$14,448,540
PW BACK TO YEAR 1
$7, 973,462
TOTAL
$17,316,689

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
PRESENT WORTH ANALYSIS
TREATMENT BY - CMUD ALTERNATE 3
DISCOUNT RATE 6.125%
TOTAL COST
ADDITIONAL
PRESENT WORTH
CONSTRUCTION
CIPS & CAPACITY
PHASE I - 2004
$11,059,000
$16,526,000
$27,585,000
PHASE 11- 2014
$828,000
$23,739,000
$13,557,000
O&M 2004
$931,000
-
-
O&M 2014
$2,336,000
-
-
O&M 2024
$3,077,000
-
-
O&M TOTAL
-
-
$22,158,000
SALVAGE VALUE
$31,518,550
$9,599,000
TOTAL =
$53,701,000
*COST INFORMATION OBTAINED FROM CMUD
O&M Present Worth CALCS
YEAR 1
$930,782
YEAR 10
$2, 335, 772
YEAR 20
$3,076,628
GRADIENT YR 1-10
$156,110.
GRADIENT YR 10-20
$82,317
PW YR 1-10
$11,393,307
PW YR 10-20
$19,506,794
PW BACK TO YEAR 1
$10,764,872
TOTAL FOR 20 YR
$22,158,179

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
0 & M
2004 •
2014
2024
ALTERNATE 1 - EXPAND PLANT
LABOR
$203,500
$203,500
$203,500
POWER
$132,000
$396,000
$792,000
SLUDGE DISPOSAL
$62,000
$186,000
$372,000
PARTS, MATERIALS & MAINTAINACE
$250,000
$750,000
$1,500,000
TOTAL
$647,500
$1,535,500
$2,867,500
ALTERNATE 2 - LAND APPLICATION
LAND APPLICATION
$172,622
$309,015
$600,332
EXISTING PLANT
$647,500
$1,535,500
$1,535,500
TOTAL
$820,122
$1,844,515
$2,135,832
ALTERNATE 3 - PUMP TO CMUD
PUMPING
$34,066
$102,200
$175,200
LABOR
$29,216
$40,072
$50,928
TREATMENT BY CMUD
$219,000
$657,000
$1,314,000
MATERIALS
$1,000
$1,000
$1,000
TREATMENT AT EXISTING PLANT
$647,500
$1,535,500
$1,535,500
TOTAL
$930,782
$2,335,772
$3,076,628

Phasing Analysis

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
PRESENT WORTH ANALYSIS
EXPAND TREATMENT PLANT - ALTERNATE 1
DISCOUNT RATE 6.125%
TOTAL COST
PRESENT WORTH
PHASE I - 2004
$12,289,000
$12,289,000
PHASE I! - 2014
$15,877,000
$8,762,000
O&M 2004
$647,500
O&M 2014
$1,535,500
O&M 2024
•
$2,867,500
O&M TOTAL
\
$16,232,000
SUB -TOTAL
•
$37,283,000
SALVAGE VALUE
$11,573,750
•$3,525,000
$33,758,000
O&M PW CALCS
YEAR 1
$647,500
YEAR 10
$1,535,500
YEAR 20
$2,867,500
GRADIENT YR 1-10
$98,667
GRADIENT YR 10-20
$148,000
PW YR 1-10
$7;634,205
PW YR 10-20
$15,579,752
PW BACK TO YEAR 1
$8,597,724
TOTAL
$16,231,929

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
PRESENT WORTH ANALYSIS
EXPAND TREATMENT PLANT - ALTERNATE 1
DISCOUNT RATE 6.125%
TOTAL COST
PRESENT WORTH
PHASE 1- 2004
$28,166,000
$28,166,000
O&M 2004
$647,500
O&M 2014
$1,535,500
O&M 2024
$2,867,500
O&M TOTAL
$16,232,000
SUB -TOTAL
$44,398,000
SALVAGE VALUE
$11,573,750
$11,573,750
$32,824,000
O&M PW CALCS
YEAR 1
$647,500
YEAR 10
$1,535,500
YEAR 20
$2,867,500
GRADIENT YR 1-10
$98,667
GRADIENT YR 10-20
$148, 000
PWYR 1-10
$7,634,205
PW YR 10-20
$15,579,752
PW BACK TO YEAR 1
$8,597,724
TOTAL
$16,231,929

Appendix D
Collection System Data
• Spill History
• Non -Discharge Permit Summary
• Infiltration/Inflow Analysis

Spill History

12 Mile WWTP Collection System Spill History
DATE
LOCATION
CAUSE OF SPILL
May 25, 2003
GALLONS SPILLED
9/22/1999 Rone Branch Outfall
1/10/1999 Rone Branch Pump Station
8/9/2000 Rone Branch Pump Station
9/9/2000 Hawfield Rd Force Main
1/12/2001 Sun Valley / Price Mill Outfall
1/16/2001 Wesley Chapel Elementary
4/19/2001 Givens Street Outfall
6/12/2001 Brandon Oaks Outfall - Phase V
6/13/2001 Colton Ridge tie-in
2/12/2002 JARRS Pump Station
8/10/2002 Stonegate Subdivision
2/22/2003 Rone Branch Pump Station
2/27/2003 Rone Branch Pump Station
3/6/2003 Rone Branch Pump Station
3/10/2003 JARRS Pump Station
3/20/2003 Rone Branch Pump Station
4/9/2003 Pine Oak Lane
4/9/2003 Rone Branch Pump Station
5/1/2003 Poplin & Hartz Rd.
6/22/2003 Goldmine Rd - MH 1591
6/30/2003 Wysacky Pump Station 3
7/14/2003 Gray Byrum Outfall
8/3/2003 Rone Branch Pump Station
12/25/2003 Rone Branch Pump Station
3/2/2004 Twelve Mile Creek Outfall
contractor's "plug" from new construction
I&I
-low voltage to station
split bell
Contractor blasted while paralleling line
force main break
grease
contractor knocked off lid & filled w/ dirt
construction debris from straddle tie-in
control breaker tripped
grease
I&I
I&I
I&I
PVC coupling cracked
I&I
l&I
i&I
force main break
grease
pump separated from flange
cone separated from riser - high flow
l&1
blown control fuse
cone separated from riser - high flow
500.00
3,366.00
28,000.00
900
466,000
450
675
500
400
750
450
19,000
6,000
16,200
800
27,600
8,000
20,000
420
2,700
200
11,600
7,350
100
9,900
IMPORTANT NOTE: On March 4, 2004 a piping problem was found at the Rone Branch Pump Station.
The piping error was allowing a large percentage of the pumped flow to recirculate back into the wetwell.
After the problem was corrected, no spills have occurred.

Non -Discharge Permit Summary

o.
0
o
Q
o
0
0
a
0
89L£
0
0
0
0
0
0
0
0
6661/81/9
1Z3L4000M
0.
0
0
0_ .
0
0
0
0
0
39E3
0
0
0
0
0
0
r0
0
6661/E/8
69144000M
0
0
0
0
0
0
0
034
9E4
BOLO
0
0
0
0
0
0
0
0
6661/6IAL
49044000M
0
0.
0
0
0
0
0
0
0
60L
0
0
0
0
0
0
0
0
66611941E
1.0944000M
0
0
0
0
0
0
0
0
0
5318
0
0
0
0
0
0
0
0
666L/83/9
89691000M
0_
0
0
0
0
0
0
0
0
IL1E
0
0
0
0
0
0
0
0
6661/9/9
4499100DM
0
0
0
0
0
0
0
0
0
0101
0
0
0
0
0
0
0
0
6661/9/9
94891000M
0
0
0
0
0
0
0
0
0
5804
0
0
0
0
0
0
0
0
66611E1/4
6999100DM
0
0 •
0
0
0
0
0
0
931
4E99
0
0
0
0
0
0
0
0
66611331E
98991000M
0
0
0
0
0
0
0
0
0
5313
0
0
0
0 -
0
0
0
0
66611611E
94991000M
0
0
0
0
0
0
0
0
0
59441
0
0
0
0
0
0
0
0
666 L/01/3
59E91000M
0 -
0.
0
0
0 .
0
0
0
6649
89031
0
0
0
0
0
0,
0
0
6661/P1/4
4LZ9100OM
0
0
0
0
0
0
0
0
3303
06
0
0
0
0
0
0
0
0
8661/01/6
SE891000M
0
0
0
0
0
0
0
01.P3
0
0
0
0
0
0
0
0
0
0
8661/93/9
84494000M
0
0
0
0 '
0
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Twelve MLte Creek WWTP Pipe
PERMIT #
DATE
2" FM
3" FM
4" FM
6" FM
8" FM
10" FM
4" GR
6" GR
8" 6R
10" GR
12" GR
15" GR
18" GR
24" GR
30" GR
36" GR
42" GR
48" GR
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET 1
FEET
WQ0001761
6/30/1989
0
0
330
0
0
0
0
0
3300
0
0
0
0
0
0
0
0
0
10748
9/19/1984
0
0
0
0
0
0
0
0
326
0
0
0
0
0
0
0
0
0
W00009231
7/13/1994
0
0
0
0
0
0
0
0
6964
0
0
0
0
0
0
0
0
0
W00009230
8/19/1994
0
0
2600
0
0
0
0
0
7424
0
0
0
0
0
0
0
0
0
W00008881
7/13/1994
0
0
0
0
0
0
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0
1369
0
0
0
0
0
0
0
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0
W00009087
7/13/1994
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0
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0
0
0
0
0
0
0
WQ0009218
7/13/1994
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0
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0
0
0
0
0
W00009077
7/13/1994
0
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1900
0
0
0
0
0
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0
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0
0
0
0
0
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7/13/1994
0
0
0
0
0
0
0
0
5577
0
0
0
0
0
0
0
0
0
WQ0020869
1/28/2002
43
WQ0020712
1/14/2002
9423
654
W00020039
7/2/2001
331
WQ0020165
8/2/2001
436
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8/20/2001
4495
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8/20/2001
2388
8/20/2001
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9/27/2001
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8/12/2002
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9/10/2002
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11/22/2002
7615
223
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12/612002
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12/20/2002
2320
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12/20/2002
2429
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12/20/2002
8284
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1/17/2003
2245
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1/7/2003
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2/7/2003
4426
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2/7/2003
112
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2/24/2003
24193
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2/24/2003
1200
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2/26/2003
1056
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4/8/2003
250
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8/12/2003
1318
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5/12/2003
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5/16/2003
5599
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5/16/2003
407
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5/22/2003
3729
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5/22/2003
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7/1/2003
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8/11/2003
11417

Twelve Mile Creek WWTP Pipe
PERMIT #
DATE
2" FM
3" FM
4" FM
6" FM
8" FM
10" FM
4" GR
6" GR
8" GR
10" GR
12" GR
15" GR
18" GR
24" GR
30' GR
36" GR
42" GR
48" GR
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
FEET
WQ0022998
8/27/2003
3684
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9/8/2003
•
4477
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9/15/2003
9598
WQ0023088
9/22/2003
1121
W 00023159
10/10/2003
15610
1695
W 00023106
9/26/2003
9092
W 00023224
10/29/2003
4924
W Q0023223
10/29/2003
4474
W00023129
9/30/2003
1338
524
WQ0023284
11 /14/2003
88
WQ0023325
12/1/2003
4984
4816
W00023478
1/7/2004
10546
W00023549
2/5/2004
1349
WQ0023551
2/5/2004
21186
W00023550
2/5/2004
3565
W00023565
2/9/2004
6564
W00023564
2/9/2004
3652
W00022105
2/23/2003
892
WQ0023647
3/8/2004
9051
_
W00023646
3/8/2004
7928
W00023710
3/25/2009
1
620
_
W00023711
3/25/2004
1205
.
WQ0023761
4/6/2004
6910
1
SUB TOTAL
9815
21762
10554
61487
4984
4440
6038
9280
792318
17890
50916
36805
20042.
43387
14347
14095
9064
4525
TOTAL FM FEET
.113042
TOTAL GR FEET
1018707
GR <18" FEET
913247
TOTAL FM MILES
21.40947
TOTAL GR MILES
192.9359
GR <18" MILES
172.9634
TOTAL PIPE FEET
1131749
PIPE FEET TO JET
91324.7
TOTAL PIPE MILES
214.3464
-
PIPE MILES TO JET
17.29639
- . 06(-4 i r[Fr 2(773 ZaT . • L NCB-- pr. /g 1Z 3f z 73
17-1O7- (f .o3 .... J1AML-&S 191-7IZ9

CI)
.c7)
0
c
0
c
c
0
0
c

Infiltration/Inflow Analysis
Twelve Mile Creek 201 Amendment
Union County, NC
1) Per Capita Water Use (Data from Union County Public Works)
Jan. 2003 Febr. 2003
a) Water consumption in billing group (residential and 28,502,000 21,682,900
commercial), gal.
b) Number of days in billing cycle 37.75 28.25
c) Average daily use, gal. 755,019 767,500
d) Number of residential meters in billing group 4,605 4,743
e) Use per meter, gpd 164 162
f) Persons per meter 2.7 2.7
g) Use (gpd per person) 60.7 60
2) Expected Wastewater Flow (January through March, 2003)
a) Total persons served at Twelve Mile Creek WWTP
Twelve Mile Creek Basin (UCPW's) 18,700
From outside basin 500
Total: 19,200
b) Expected residential Flow
Q=19,200 persons (60 gpd/person x .90) 1,036,800 gpd
c) Industrial flow (metered) 2,900 gpd
d) Institutional flow (estimated) 100,000 gpd
e) Total expected flow 1,139,000 gpd
3) Il1 Estimate (April, 2003)
a) Average daily WWTP flow 1.967 mgd
b) Expected flow 1.139 mgd
c) Excess flow (infiltration) 0.827 mgd
d) Inch -Miles of Pipe 1,774
e) Infiltration 466 gpd/inch-mile
4) lnflow Estimate (2003)
a) Max 24-hour flow 3.400 mgd
b) lnflow per person served 177 gpd
1\4(1 M&CREED

Appendix E
Sludge Management Plan

Final Report
Sludge Management Analysis
Union County, NC
. a:•:_ ..:1t:.l
unasnMIIIIiMill n,
1nhul
RIM
■.w
n �ymen
J�1f6 1 r?ii 14111
Prepared by:
McKim & Creed, PA
8020 Tower Point Drive
Charlotte, NC 28227

Final Report
Sludge Management Analysis
Union County, NC
Prepared by:
McKim & Creed, PA
8020 Tower Point Drive
Char[otfe, NC 28227

Table of Contents
Section 1 -- Introduction
1.1 -- Background 1
1.2 -Scope of Work 1
Section 2 -- Existing Aerobic Stabilization Facilities
2.1 - General 3
2.2 -- Crooked Creek 3
2.3 - Twelve Mile Creek 3
2.4 - Land Application 4
Section 3 - Waste Sludge Production
3.1 -- General 5
3.2 - Waste Sludge Production 5
Section 4 - Sludge Management Alternatives
4.1 - introduction 7
4.2 - Aerobic Stabilization / Land Application 8
4.3 - Class "A" Biosolids - lime Heat Processing 8
4.4 - Sludge Management Plan Comparison 9
4.5 - Implementation 10
Section 5 -- Summary and Recommendations
5.1 -- Summary 12
5.2 - Recommendations 12

SECTION 1 - INTRODUCTION
1.1 Background
Union County operates two significant wastewater treatment facilities, The Crooked
Creek Facility (NPDES Permit NC 0069841), located on Sardis Church Road at the South
Fork of Crooked Creek, is a 1.9 MGD treatment plant currently treating a flow of about
1.0 MGD. The Twelve Mile Creek Plant (NPDES Permit NC 0085359) located on NC 16 at
Twelve Mile Creek is a 2.5 MGD treatment plant, also treating a flow of about 1.0 MGD.
Waste sludges at each of these two facilities is aerobically stabilized, and then
beneficially reused by application to agricultural sites.
To meet projected growth in western Union County, the Twelve Mile Creek facility is to be
re -rated to increase the permit capacity to 3.0 MGD; and then the capacity will be
doubled to 6.0 MGD through an expansion of the treatment system. As a part of the
expansion, additional aerobic sludge processing facilities are proposed.
Although the current sludge management program works well, limitations include
disposal of liquid sludge during winter months and other times when agricultural
practices limit sludge application. Also, the County has experienced some problems in
meeting EPA criteria for Class "B" sludge, notably volatile solids reductions. When this
occurs, the County must further stabilize sludge by lime addition, which increases cost
and delays sludge removal.
Thus, before proceeding with the expansion of the existing aerobic stabilization system at
Twelve Mile Creek, the County authorized this review to compare existing sludge
management practices to other options, particularly processing sludge to a Class 'A"
product. Class "A" sludge is more stable; and, under EPA regulations, can be ultimately
disposed of with fewer limitations.
1.2 Scope of Work
The scope of this investigation includes the following activities:
A. Prepare updated waste sludge production estimates for the Twelve Mile and
Crooked Creek wastewater treatment plant service areas for a ten year period.
B. Identify improvements required at the Twelve Mile Creek and Crooked Creek
WWTP to continue to aerobically stabilize/land apply liquid sludges.
C. Prepare process flow sheets, equipment sizing, basis of design and capital cost
estimates to install lime stabilization/pasteurization (Class A) sludge processing at
a remote site (County landfill) sized for all Union County sludges.
D. Prepare design basis equipment sizing and cost estimates to construct Class A
facility at Twelve Mile Creek with transportation of sludge from Crooked Creek to
this site.
E. Identify infrastructure needs (water/sewer) to construct Class A facility at the
landfill.
F. Prepare O&M estimates for Class A sludge options described above. Include
chemicals, labor, maintenance and replacement, and transportation.
00771.0023
November 1, 2004
Page 1

G. Using existing contracts, estimate costs to continue with the liquid sludge
operations.
H. Prepare life cycle and present worth cost analysis of options for a 10-year period.
i. Prepare a draft Technical Memorandum describing the work performed and
recommended waste sludge management plan.
J. Meet with OWNER to review draft Waste Sludge Management Plan.
K. Incorporate OWNER comments and submit final report on Waste Sludge
Management Plan.
00771.0023
November 1, 2004
Page 2

SECTION 2 - EXISTING AEROBIC STABILIZATION FACILITIES
2.1 General
Aerobic stabilization of waste sludge, as operated by Union County, involves wasting
activated sludge from the biological process info holding tanks, where thickening to a
solids concentration of between 3-4% occurs. Simultaneously, the thickened sludge is
mixed and aerated to reduce volatile solids. To comply with EPA regulations, the County
must achieve a 38% volatile solids reduction to be deemed as a Class "B" product, which
can then be land applied to permitted sites.
While the aerobic stabilization processes at each treatment plant are similar, they differ in
several details.
2.2 Crooked Creek
Facilities at Crooked Creek include the following:
a.
b.
Two (2) aerobic digesters (45-foot diameter by 16.5-foot water), each having a
volume of 200,000 gallons. Each tank is mixed with a 30 Hp floating aerator.
Two (2) aerobic digesters (76-foot diameter by 16.5-foot liquid depth), each
having a volume of 575,000 gallons. Each of these tanks is equipped with 75 Hp
floating aerators.
c. One (1) stabilized sludge storage tank, 76-foot diameter by 16.5-foot depth. This
tank uses a 75 Hp floating aerator for mixing and stabilization.
Waste activated sludge is pumped into one of the digesters, where the contents are
alternately mixed/aerated to reduce volatile solids, and allowed periods of quiescent
settling so that the tank can be decanted to increase total suspended solids to a target
value of 4%. Once the sludge is stabilized, the contents are usually transferred to the
holding tank for an additional period of stabilization proceeding land application.
This facility uses floating aerators for mixing and aeration; and because this method of
aeration results in heat loss, EPA protocol requires a minimum solids retention time (SRT) of
90 days to meet Class `13" requirements.
2.3 Twelve Mile Creek
Facilities for sludge processing at Twelve Mile Creek include a rotary sludge thickener;
two (2) aerobic digesters, each with a volume of 250,000 gallons; and one (1) 1.0 MG
digester.
a. Two (2) 50-foot diameter by 18-foot deep digesters, each mixed/aerated with a
single 40 Hp positive displacement blower and a coarse bubble diffuser system.
Each tank has a piping system to allow manual decanting for thickening.
b. One (1) 96-foot diameter by 18-foot deep circular digester with a volume of 1.0
million gallons. This tank is mixed/aerated by two (2) 125 Hp positive
displacement blowers and a coarse bubble diffuser system. This tank also has a
decant piping system.
00771.0023
November 1, 2004
Page 3

c. A rotary thickener sized for a flow of 100 gpm to mechanically thicken waste
sludge to a concentration of about 4%.
Under current operations, sludge is wasted into any one of the three tanks, manually
thickened by decanting, and stabilized by aeration. Stabilized sludge is land applied.
The rotary thickener is not currently used. Waste sludge practices do not currently require
the use of this equipment. As sludge wasting increases, it will be more desirable to use
mechanical thickening.
1n contrast to Crooked Creek, Twelve Mile Creek utilized diffused aeration for mixing and
oxygen transfer. This system does not result in the same temperature loss as does surface
aeration, and thus the required SRT is reduced to 45 days. This allows smaller tankage to
achieve process requirements and less mixing/aeration horsepower. The Crooked Creek
facility has a total of 2.15 MG of tankage (1.13 MG/MGD), with 285 Hp (150 Hp/MGD of
capacity) of aerators for stabilization. By comparison, Twelve Mile Creek has 1.5 MG of
tankage (0.5 MG/MGD of rated capacity), and 110 Hp/MGD of capacity.
2.4 Land Application
Sludge is removed from each of the facilities by tanker truck, and applied to permitted
agricultural sites by contract. When either the oxygen uptake or volatile solids reduction
criteria are not met, the sludge must be lime stabilized prior to disposal.
Generally, the land application program works well. The chief drawback to this program
is lack of flexibility to land apply sludges during Inclement weather, or when the sludge
must be lime stabilized if oxygen uptake or volatile reductions goals are not met.
00771.0023
November 1, 2004
Page 4

SECTION 3 - WASTE SLUDGE PRODUCTION
3.1 General
Growth in the western portions of the County coupled with the number of non -discharge
permits issued have been used to predict wastewater flows to the Crooked Creek and
Twelve Mile Creek treatment systems. These projections and the resulting waste sludge
production rates were used to compare sludge management options for the next ten
(10) years.
Waste sludge production at each plant site reflects County plans to place the North Fork
Crooked Creek Diversion Pump Station online. This system will allow the Crooked Creek
WWTP to operate at hydraulic rates of 1.5 to 1.9 MGD, with the balance of the flow and
resulting waste sludge transferred to the Twelve Mile Creek WWTP.
For the purpose of this analysis, the flow projections shown in Table 1 will be used to
estimate waste sludge projections.
Table 1
Wastewater Flow Projections, MGD
3.2 Waste Sludge Production
Both the Crooked Creek and Twelve Mile Creek plants utilize extended aeration
processes based on oxidation ditch technology; and both facilities receive flow
comprised of domestic wastewater of "average" strength. Waste solids production at
each site Is estimated to be about 1334 pounds/million gallons of waste treated. This
represents the approximate pounds of waste solids sent to the sludge stabilization system
at each site.
00771.0023
November 1, 2004
Page 5

Table 2
Waste Solids Production, #/Day
These values reflect the total pounds of sludge to be processed.
00771.0023
November 1, 2004
Page 6

SECTION 4 - SLUDGE MANAGEMENT ALTERNATIVES
4.1 Introduction
This analysis compared two (2) sludge stabilization/disposal options. The current program
uses aerobic stabilization and disposal of liquid sludge by land application. The
proposed alternative uses lime stabilization to produce Class "A" biosolids, which will be
applied on agricultural sites. This section discusses each alternative.
4.2 Aerobic Stabilization / Land Application
The current process at each site involves wasting excess solids into aerobic digesters.
Stabilization is achieved by aeration. Crooked Creek uses mechanical surface aerators,
and Twelve Mile Creek uses positive displacement blowers and diffusers. At both sites,
decanting is used to thicken the waste sludge to about 3.5% to 4% prior to land
application.
Each facility currently uses aerobic digestion to produce Class "B" biosolids. This process
achieves a reduction in volatile solids of around 40%. Based on operating records, the
waste sludge averages about 66% volatiles. Applying the 40% reduction in volatiles
achieved in the aerobic stabilization process yields a net total solids reduction of about
26%. Thus, for each 1 MGD of wastewater treated, 1334 pounds of solids goes into the
sludge processing system, and about 990 pounds of aerobically stabilized solids are
disposed of by land application. Table 2 summarizes the projected waste sludge at
each treatment plant site over the next ten years. At 3.5% solids concentration, the
volume of wastewater sludge land applied equals 3392 gal/MG of waste treated.
The existing Crooked Creek sludge facilities are sized for the plant rated flow of 1.9 MGD.
Twelve Mile Creek will require an additional 1.0 MGD aerobic digester with diffused air
and blowers, along with site piping, electrical, and related site improvements. The
estimated cost of these improvements is $1,363,000, and will result in a system sized for a
plant capacity of 6.0 MGD.
Operating costs for continued operation of the existing aerobic stabilization/disposal
plan have been estimated. Union County staff assisted in estimating the total energy
used at current flows based on wasting schedules and pump -out cycles. Operating
costs include labor for decanting and cleaning digesters, and electricity to power the
aeration systems.
Land disposal costs were estimated using a net cost of $0.03/gallon for pumping, hauling,
permitting, testing, and disposal. Total volumes were based on 3.5% solids
concentrations. A summary of the costs for continuing the existing program is shown in
Table 3.
00771.0023
November 1, 2004
Page 7

Table 3
Capital / Operating Costs
Aerobic Stabilization / Land Application
4.3 CIass "A" Biosolids - Lime / Heat Processing
There are a number of proprietary processes that produce Class "A" biosolids by
elevating the sludge temperature and pH in a controlled reaction. For the purpose of
this analysis, the Bioset® process has been evaluated.
This process involves dewatering waste activated sludge to a solids concentration of 15-
17%, and then combining the dewatered sludge with lime and acid in a "pressure"
reactor. The resulting stabilized Class "A" biosolids can be land applied as a soil
amendment within the limitations of EPA regulations.
The equipment for the Biosef® process has been sized to handle seven (7) days of waste
sludge in 40 hours of actual operation. This system requires a two -meter belt filter press
capable of dewatering 100 gpm or about 2000 pounds per hour of sludge solids to a
concentration of 15% or greater. The dewatered sludge is blended with lime and acid in
a BiosefO reactor. Related equipment includes a sludge feed pump and a polymer
system for the belt press; a sludge conveyor; a "Bridge Breaker" progressive cavity feed
pump for the Bioset® system; and associated lime and acid storage and feed systems.
The Bioset® reactor incorporates a scrubber for odor control.
The above system is proposed as a "single train" system without backup equipment
since both the Crooked Creek and Twelve Mile Creek plants already have aerobic
digestion which can be used if the Class "A" system is down for maintenance.
There are two options for the site of the Class "A" biosolids system. The first option is to
locate the Class 'A" processing facility at a remote site. One such site is adjacent to the
closed Union County landfill. This site is about 17.5 miles from the Twelve Mile Creek plant,
and 15 miles from the Crooked Creek plant. This site is convenient for delivery of
chemicals, and offers excellent access for end users of the stabilized sludge. The landfill
site does not have water or wastewater services, and would require pumping
wastewater back to the City of Monroe system for treatment. This site would also require
liquid sludge storage.
The second option is at the Twelve Mile Creek Treatment Plant. This site offers ample
sludge storage in existing tanks, reuse water for chemical makeup and equipment
washdown, and existing infrastructure to process the wastewater from the dewatering
00771.0023
November 1, 2004
Page 8

operation. Also, since about 75% of the sludge will be produced at this site,
transportation costs are limited to bringing sludge in from Crooked Creek and hauling
away the Class "A" biosolids. The chief disadvantage of this site is the proximity of
residential developments and a planned office/retail center on 150 acres immediately
adjacent to the plant site. Truck access/egress and potential complaints related to the
operation of the Class "A" facilities are concerns
Appendix A summarizes costs associated with providing water, sewer, and electric
utilities to the remote site, along with other improvements including sludge storage and
wastewater pre-treatment systems. The capital cost to locate the Class "A" facilities at
the landfill is estimated to be $2,486,000. . The estimated cost to construct Class "A"
processing facilities at the Twelve Mile Creek site is $1,319,000.
Operating costs for the Class "A" Bioset® system include labor, electricity, water and
polymer for the dewatering system; and electricity, lime, acid, and labor for the Bioset®
reactor. Estimates on a "per ton" of sludge processed are included in the analysis.
Hauling costs are a significant factor in the operation of the Class "A" system. These
have been estimated for each option based on haul distances and sludge volumes. It
was assumed that the County would purchase a truck/tanker trailer for liquid sludge, and
an additional watertight dump trailer to haul processed sludge away from Twelve Mile
Creek.
Appendix A includes a estimate of operating costs associated with the Class "A" system.
These are summarized in Table 4.
Table 4
Capital / Operating Cost
Class "A" Biosolids System
The differences in O&M between the two options for a Class "A" facility are associated
with hauling liquid sludge from Twelve Mile Creek to the remote site.
4.4 Sludge Management Plan Comparison
There are different capital and operating costs associated with each alternative and the
site identified for the Class "A" facilities. Appendix A presents a comparison of the
alternates using two approaches. The first is a "life cycle" approach where capita! costs
are amortized on a 20-year basis at 6% to create an annual "debt service" cost.
Operating costs are based on chemicals, utilities, labor, fuel, etc. required to process the
projected sludge quantities using a "straight line" growth curve over ten years. All
operating costs are expressed in 2002 dollars.
00771.0023
November 1, 2004
Page 9

The second approach is to use a "present" value analysis. For this analysis a 6% discount
rate was used; and it was assumed that the system has a 30% salvage value after ten
years.
Table 5 compares the alternates on the basis of capital, life cycle cost and present
value.
Table 5
Cost Comparisons
Sludge Management Alternates
Capital
Class "A" Processing
at Twelve Mile Creek
$5; 7ba 400
The capital cost of a "single train" Class "A" facility located at the Twelve Mile Creek site
compares favorably to aerobic stabilization. Locating the Class "A" facility to the landfill
is more expensive, due to the additional infrastructure needed.
Life cycle and present value comparisons favor a Class 'A" system at Twelve Mile Creek.
The chief disadvantage of this location is the proximity of commercial/residential
development.
4.5 Implementation
The cost analysis indicates that development of a Class "A" biosolids facility utilizing a
single train Bioset® process has a lower life cycle and present value cost compared to
continued land application of aerobically stabilized Class "B" liquid sludge. The results of
the analysis were reviewed with Union County Public Works staff. As noted above, staff
members are concerned that planed residential/ commercial development immediately
around the Twelve Mile Creek site would make it difficult to effectively operate a Class
"A" biosolids system at this location. This factor influenced the County decision to
continue with the current plan of land application of liquid sludge when the Twelve Mile
Creek Wastewater Treatment Plant is expanded.
The concept of a centralized Class "A" sludge processing system has not been ruled out,
however. Union County plans to construct a major new wastewater treatment facility on
Grassy Branch in the northern part of the County. At that time the opportunity to
consolidate sludge processing to a single site should be reviewed. The cost associated
with large aerobic digesters and associated equipment required for an advanced
treatment plant in the 5.0 mgd capacity range will likely be in the $3.0 million dollar
range, based on experiences at Twelve Mile Creek. Much of this cost could be avoided
if long term sludge stabilization/storage tanks could be replaced with much smaller
00771,0023
November 1, 2004
Page 10

waste sludge holding tanks at the new treatment plant site. The capital cost savings
could then be applied towards the construction of a single Class "A" processing facility.
Finally, in July, 2004, McKim & Creed and Union County Public Works met with the City of
Monroe's Water Resources Department to discuss sludge handling/disposal issues.
Currently the City of Monroe utilizes the same process for sludge stabilization/ disposal at
its Richardson Creek WWTP as does Union County. It was reported that the City faces
many of the same issues as the County in managing sludge disposal, particularly during
wet periods. Current facilities are adequate; however, the City expressed a desire to be
included in the analysis of options for a future Class "A" system. The City noted that the
Richardson Creek WWTP is centrally located in Union County, and would be equidistant
from the Twelve Mile Creek and Grassy Branch sites. Space is available to 'host" a
centralized Class "A" facility; and many of the infrastructure costs required at the County
landfill site could be avoided. Further study would be required to confirm the suitability of
this option.
if the engineering analysis confirms the cost advantage of constructing a Class "A"
facility at the Richardson Creek WWTP, other strategic issues such as ownership and inter -
municipal arrangements would need to be resolved. Union County currently has an
ownership interest in the Richardson Creek WWTP; and a jointly owned Class "A" facility
could be an extension of the current inter -local agreements. First, however, the
engineering aspects of this location would need to be explored.
00771.0023
November 1, 2004
Page 11

0
SECTION 5 - SUMMARY AND RECOMMENDATIONS
5.1 Summary
Union County currently operates two (2) significant wastewater treatment facilities
(Crooked Creek and Twelve Mile Creek), and is planning a third facility on Grassy Branch.
Current sludge management practice is land application of liquid Class "13" sludge for all
County -owned wastewater treatment plants.
McKim & Creed evaluated sludge production data and alternatives to the current Class
"B" land application system. Over the next ten years, sludge production at County -
owned facilities will increase by about 400% to about 10,500 pounds per day. Three
options to manage the stabilization and disposal of sludge were reviewed, including
continuation of liquid disposal and lime stabilization at two different locations.
Continuation of liquid sludge disposal has the lowest ten-year capital cost, followed very
closely by a Class "A" facility at Twelve Mile Creek. The Twelve Mile Creek Class "A"
option is significantly lower in both life cycle and present value than continuing the liquid
sludge program. Locating a Class "A" facility at the closed County landfill is the least
desirable option from a cost standpoint, due largely to the infrastructure costs to develop
this site. Concerns about development around and adjacent to the Twelve Mile Creek
WWTP site influenced the County decision to not add a Class "A" sludge processing
system at this location. The County will continue, for the immediate future, the liquid
sludge application program.
Union County reviewed the results of this investigation with the City of Monroe, who
operates a similar program. The City has expressed interest in a joint Class "A" facility
when the Richardson Creek Wastewater Treatment Plant is expanded, and is willing to
"host" a facility under an appropriate inter -local arrangement. Further study would be
required to determine the economic feasibility of locating a Class "A" facility at the City's
treatment plant.
5.2 Recommendations
The following recommendations are offered:
A. Expand the scope of this study to consider locating the Class "A" facilities at the
Richardson Creek site instead of the County landfill with or without capacity for
the City of Monroe.
B. Evaluate long range sludge management program needs to include both the
planned County Grassy Branch WWTP and capacity to handle part or all of the
City of Monroe's sludge, as well as Twelve Mile Creek and Crooked Creek.
The above steps will assist in defining an appropriate long range sludge management
strategy if undertaken promptly, and avoid construction of unnecessary sludge storage
facilities at Twelve Mile Creek and better define facilities needed at the planned Grassy
Branch WWTP.
00771.0023
November 1, 2004
Page 12

Appendix A

Appendix F
User Charge Analysis

Actual and Projected Results of Operations and Capital Improvements
Appendix A
Sewer Sewer Sewer
Actual Actual (UNA) Projection
June 30 June 30 June 30
2003 2004 2005
Operating Revenues
1 Charges for services 6,277,874 6,848,690 7,254,100 1
2 Other operating revenues 168,507 374,821 295,532
3 Total operating revenues 6,446,381 7,223,511 7,549,632
Operating Expenses
4 Personnel
5 Operating
6
Total operating expenses
(2,047,736) (2,156,202) (2,390,915)
(3,036,168) (2,736,924) (3,761,940) 2
(5,083,904) (4,893,126) (6,152,855)
7 Operating income 1,362,477 2,330,385 1,396,777
Nonoperating Revenues (Expenses)
8 Water & sewer capacity and taps 3,205,949 5,205,171 5,348,610 3
9 Investment earnings 290,504 205,358 326,150
10 Gain on sale of fixed assets 7,125,536 14,014 41,250
11 Federal grant 5,806
12 Interest and Fees (1,949) (33,585) (6,000)
Total nonoperating revenue
13 (expenses) 10,625,846 5,390,958 5,710,010
14 Net Revenues Available for Debt Service & Capital 11,988,323 7,721,343 7,106,787
Senior Debt Service
15 Revenue Bonds 1,204,826 1,911,341 1,949,185
16 CIP Revenue Bonds
17 Total Senior Debt Service 1,204,826 1,911,341 1,949,185
Subordinated Debt Service
18 1995 NC State Revolving Loan 386,710 345,918 337,902
19 GO Debt Service 1,292,610 1,242,002 1,151,391
2004 NC State Revolving Loan - 1,338,667 4
20 Total Subordinated Debt Service 1,679,320 1,587,920 2,827,960
21 Total Debt Service 2,884,146 3,499,261 4,777,145
Coverage Test - Section 6.6 (b)
22 Net Revenues/Total Debt Service (1.0X) 4.16 2.21 1.49
23. Net Revenues Available After Debt Service 9,104,177 4,222,081 2,329,642
24 Capital Outlays (625,681) (473,723) (334,100)
25 Remaining Available Funds 8,478,496 3,748,358 1,995,542 5
Total Beginning Cash & Investments (incs. req. working
26 cap.) 11,418,194 19,896,690 20,242,288
27 Remaining Available Funds 6,478,496 3,748,358 1,995,542
28 Transfers to CIP projects (3,402,760) (2,785,000)
29 Total Ending Cash & Investments (incs.req. working cap.) 19,896,690 20,242,288 19,452,831
9/28/2004

Actual and Projected Results of Operations and Capital Improvements
1 Sewer Operating Revenue projection reflects 8% increase over FY04 actual revenue. Recent trend suggests
9.4% increase is likely. FY05 first quarter actuals exceed same period for FY04 by 34.8%.
2 $647,500 increased O&M expenses associated with 12 Mile WWTP Expansion.
3 Sewer Nonoperating Revenue (Capacity/Tap Fees) projection reflects 3% increase over FY04 actual revenue
(unaudited). Recent trend is inconclusive due to policy change in FY01. However, FY05 first quarter actuals
exceed same period in FY04 by 28.2%.
4 Assumes level principal payments, declining interest payments. Financing is at 4% for 15 years term.
5 Financing for 12 Mile WWTP Expansion individually has no impact on current wastewater fees and
rates.
i
9/28/2004

Union County North Carolina
Page 1 of 4
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Water & Sewer Rate
Schedule
Palk Wa
Jon C. Dyer, P.E. - Director
400 North Church Street
Monroe, NC 28112
[phone]
HOURS: 8 a.m.- 5 p.m.
Monday - Friday
Select a County Office...
If you currently have a water leak, a sews
backup please call 704-289-1591 to repo
emergency. Use the number only on wee
holidays or after hours (5 p.m. - 8 a.m.) IV
Friday
Water and Sewer Rates
Rates or fees listed in these web pages are subject to change without prior notice.
Please call [phone] for verification. Last update July, 2001.
• Monthly Base Charge
• Monthly Service Charges
• Additonal Fees
• Water & Sewer Capacity Fees
• Tap Fees
• Fire Connection Fees
Monthly Base Charge:
Water
Sewer
Meter Size
Monthly Amount
Monthly Amount
3/4"
$ 5.00
$ 9.25
1 °
$ 12.60
$ 23.31
1 1 /2"
$ 25.05
$ 46.34
2°
$ 40.05
r
$ 74.09
3"
$ 112.70
$ 208.50
4"
$ 250.45
$ 463.33
6°
' $ 350.60
$ 648.61
(Residential accounts are normally 3/a°)
htto://www.co.union.nc.us/gov_offices/public_works/rates.htm 9/28/2004

Union County North Carolina
Page 3 of 4
2"
$ 4,000.00
$ 21,225.00
3"
$ 11,250.00
$ 59,725.00
4"
$ 25,050.00
$ 132,725.00
6"
$ 35,050.00
$ 185,825.00
(Residential accounts are normally3/44)
Tap Fees:
Sewer (Tap Fee by Size of Line)
Water (Tap Fee by Meter Size)
4"
6"
>6°
3A"
1"
11/2
$630.00
$825.00
Cost
$400.00
$525.00
$2,600.00
Fire Connection Fees:
Capacity Fee — No Charge
Tap Fee — At Cost
Here is an example cost for installation of a typical 3/a° residential meter & a 4" sewer line. Cost in thi
example were based upon current prices, using estimates, and is not meant to be a definitive price li
[phone] for verification of costs.
Water
Sewer
Capacity Fee
$ 500.00
$2,650.00
Tap Fee
$ 400.00
$ 630.00
Total
$900.00
$ 3280.00
Total for both water & sewer = $4,180.00
Disclaimer
ALL RIGHTS RESERVED, COPYRIGHT 2004. CONTACT THE WEBMASTER.
http://www.co.union.nc.us/gov_offices/public__works/rates.htm 9/28/2004

Union County North Carolina Page 2 of 4
Monthly Service Charges:
(in addition to the monthly base charge)
o Base Facility Charge (Fixed amount varies by meter size)
o Volume Charge Water per 1,000 Gallons of metered usage
Residential Customers (standard 3A" household meter)
First 3,000 Gallons $2.10
Next 7,000 Gallons $2.45
Over 1 0,000 Gallons $3.45
Non Residential Customers and Irrigation Meters - $2.45
• Volume Charge Sewer per 1,000 Gallons of metered usage - $3.30 **
Sewer Cap Rates (Effective Summer 2003)**
Residential customers with a 3/4" meter will receive a sewer billing cap for the summer month:
(approximately 5 months). Under the current sewer billing cap policy, the maximum usage tha
customer is billed for is 14,000 gallons per bill cycle.
** Fairfield Sewer- $15.00 (base fee) plus $4.35 per 1,000 gallons used
(example: billed for 4,400 gallons - 4.400 x $4.35 =$19.14 + $15.00 = $34.14)
Additionai Fees:
• Rental Deposit - $50.00 (applied to renters or customers who do not own their homes).
• Service Charge - $25.00 (applied to new accounts).
• Late Fee - $5.00 (applied after the past due date).
• Reconnection Fee - $50.00 (due before service is restored).
Water and Sewer Capacity Fees:
(Capacity fees simply stated are fees charged upon an original connection to any County water or s(
fine. This fee is used for expansion to ensure adequate water & sewer plant capacity for current and
use in relation to the demands placed on the system by an additional customer.)
Meter Size
Water
Sewer
34,"
$ 500.00
$ 2,650.00
1"
$ 1,250.00
$ 6,675.00
1 W/z°
$ 2,500.00
$ 13,275.00
„o/n,c, nffinaolr it lir cirorlre/rntae htm
Q/932/711flet

Union County North Carolina Page 4 of 4
Union County North Carolina does not endorse content on external sites.
1
httn://www.co.union.nc.us/2ov officesfDublic_works/rates.htm 9/28/2004

Appendix G
Environmental Review
■ E/A Document (Bound Separately)
■ FONSI

T
z

Michael F. Easley, Governor
William G. Ross Jr., Secretary
North Carolina Department of Environment and Natural Resources
Alan W. Klimek, P.E. Director
Division of Water Quality
September 17, 2004
Mr. Jon C. Dyer, P.E., Director
Union County Public Works Department
400 N. Church Street
Monroe, NC 28112-4804
Subject: Environmental Assessment; Twelve Mile Creek Wastewater Treatment Plant Expansion
Dear Mr. Dyer:
The NC Environmental Policy Act review for the subject project is complete. Comments were
received during the course of the State Clearinghouse review (see attached letter from the
Clearinghouse); however, due to the nature of the comments no further review action is required.
Permit applications covering activities associated with this project may now proceed. The
applications should be consistent with the Finding of No Significant Impact issued by the
Division of Water Quality on August 9, 2004 (attached).
If there is anything else I can assist you with, please give me a call at 919.733.5083 ext. 555.
Sincerel
J
Alex • arks, AICP
Environmental Specialist
cc: Dave Goodrich
Melba McGee
✓Sid Riddick, PE
/Nao Caroina
turally
North Carolina Division of Water Quality/Planning Branch 1617 Mail Service Center Raleigh, NC 27699-1617 Phone [phone]
http//www.h2o.enr.state.nc.us
512 North Salisbury St. Raleigh, NC 27604 FAX [phone]
DENR Customer Service 1-877-623-6748 An Equal Opportunity/Affirmative Action Employer

FINDING OF NO SIGNIFICANT IMPACT
Environmental Assessment for the Twelve Mile Creek Wastewater Treatment
Plant Expansion Project
Union County Public Works Department
August 9, 2004
Pursuant to the requirements of the North Carolina Environmental Policy Act (N.C.G.S. § 113A-
1$ etseq.), an environmental assessment (EA) has been prepared for the expansion of the existing -
Twelve Mile Wastewater Treatment Plant (WWTP) in Union County. The proposed project
will expand the plant's existing permitted capacity of 2.5 million gallons per day (MGD) to 6.0
MGD. Growth in the Twelve Mile Basin area of the County has been rapid. The plant is
currently operating at 40% of its rated capacity and Union County has issued non -discharge
permits committing 100% of the available capacity. These factors, plus planning projections,
show a need for the project.
The plant, constructed in 1996 is located on an 88-acre parcel, approximately 4,000 feet west of
NC 16 along Twelve Mile Creek in the Town of Waxhaw. Beyond the WWTP, Twelve Mile
Creek flows directly into the Catawba River downstream from Lake Wylie near Van Wyck, SC.
The creek is in the Catawba River sub -basin 03-08-38. The plant will serve an area of
approximately 93 square mules, which includes the towns of Waxhaw, Mineral Springs, and
Wesley Chapel, portions of the towns of Stallings and Indian Trail, much of the town of
Weddington, and unincorporated portions of the basin. Union County provides sewer and water
services to the entire basin.
Alternatives analyzed for the EA include constructing a land application system and discharging
wastewater to the Charlotte -Mecklenburg Utility System. The selected alternative, expansion of
the existing plant capacity, was chosen as it offers the lowest capital and present value costs.
All construction associated with the proposed expansion will occur immediately adjacent to the
existing facility on land already disturbed. Following required federal and state permit
conditions will minimize potential direct impacts. An Erosion and Sedimentation Control Plan
will be submitted to DENR for approval before construction commences.
Secondary and cumulative impacts associated with land development occurring within the
service area may result from the project. Various town ordinances and land development
regulations of the municipalities within the project's service area as well as Union County will
mitigate many of these impacts. These regulations include various smart growth provisions,
open space, and riparian buffer protection regulations.
Based on the findings of the EA, review by governmental agencies, and the impact
avoidance/mitigation measures contained therein, it is concluded that the proposed project will
not result in significant impacts to the environment. This EA and Finding of No Significant
Impact are prerequisites for the issuance of an NPDES Discharge Permit by the Division of
Water Quality. Pending approval by the State Clearinghouse, the environmental review for this
project will be concluded. An environmental impact statement will not be prepared for this
project.
North Carolina Division of Water Quality, Water Quality Section
August 9, 2004

r
North Carolina
Department of Administration
Michael F. Easley, Governor Gwynn T. Swinson, Secretary
September 14, 2004
Mr. Alex Marks
DENR, Water Quality
1617 MSC
Raleigh, NC 27699-1617
Dear Mr. Marks:
Re: SCH File # 05-E-4300-0040; Environmental Assessment/Finding of No Significant Impact;
Expansion of the 12 Mile Creek Wastewater Treatment Plant in Waxhall , N.C.
The above referenced environmental impact information has been reviewed through the State
Clearinghouse under the provisions of the North Carolina Environmental Policy Act.
Attached to this letter are comments made by agencies in the course of this review. Because of the
nature of the comments, it has been determined that no further State Clearinghouse review action on
your part is needed for compliance with the North Carolina Environmental Policy Act. The attached
comments should be taken into consideration in project development.
Best regards.
Sincerely,
sty
• Ms. Chrys Daggett
•Environmental Policy Act Coordinator
Attachments
cc: Region F
Mailing Address: Telephone: [phone] Location Address:
I301 Mail Service Center Fax [phone] West Jones Street
Raleigh, NC 27699-130! State Co Tier t151-01-00 Raleigh, North Carolina
e-mail Cluys.Baggett o ncmail.net
An Equal Opportunity/Affirmative Action Employer

NORTH CAROLINA STATE CLEARINGHOUSE
DEPARTMENT OF 1-:DMINISTRATION
INTERGOVERNMENTAL REVIEW
tihAt
MR PHIL LETSINGER
CLEARINGHOUSE COORD
CC&PS - DEM, NFIP
MSC # 4716
RALEIGH NC
REVIEW DISTRIBUTION
CC&PS -- DEM, NFIP
CENTRALINA COG
DENR LEGISLATIVE AFFAIRS
DEPT OF CUL RESOURCES
DEPT OF TRANSPORTATION
PROJECT INFORMATION
APPLICANT: DEnr, Water Quality
TYPE: State Environmental Policy Act
STATE NUMBER: 05-E-4300-0040
DATE RECEIVED: 08/11/2004
AGENCY RESPONSE: 09/08/2004
REVIEW CLOSED: 09/13/2004
ERD: Environmental Assessment/Finding of No Significant Impact
DESC: Expansion of the 12 Mile Creek Wastewater Treatment Plant in Waxhall , N.C.
CROSS-REFERENCE NUMBER: 03-E-4300-0009
The attached project has been submitted to the N. C. State Clearinghouse for
intergovernmental review. Please review and submit your response by the above
indicated date to 1301 Mail Service Center, Raleigh NC 27699-1301.
If additional review time is needed, please contact this office at [phone].
AS A RESULT OE THIS REVIEW THE FOLLOWING IS SUBMITTED:
'1 1 NO COMMENT
COMMENT r CHE
SIGNED BY:
DATE:

c
cJ
North Carolina Department of Crime Control and Public S
Division of Emergency Management
Floodplain Management Branch
Michael F. Easley, Governor Bryan E. Beatty,
Division of Emergency Management
National Flood Insurance Program
STATE NUMBER: 05-E-4300-0040
APPLICANT: DENR, Water Quality
si4r[£l2
Secretary
DESC: Expansion of 12-Mile-Creek Wastewater Treatment Plant in Waxhall, NC
Given the rough location provided in the final EA, the plant proposed to be expanded
may be located in a Base Flood (AE) Zone. Before commencement of any work on the
structure, a detailed determination of the specific location in relation to the Union County
FIRM (Panel 70, dated July 5, 1994) must be made.
If the project is determined to be located in the AE zone, flood protection measures
must be taken. Because the proposed project would be a substantial improvement of
the existing structure, all new construction and existing construction must meet current
construction standards outlined in the Union County Flood Damage Prevention
Ordinance, even if the original structure was grandfathered.
Please contact the local Floodplain Administrator to determine the floodplain
designation and to find out specific regulations, if applicable.
ave Lentzne
Division of Emergency Management — NFIP
919-715-8000 extension 351
MAILING ADDRESS:
Disaster Recovery Operations
Center (DROC)
4713 Mail Service Center
Raleigh, NC 27699-4713
Fax: [phone]
www.ncem.org
NC Division of Emergency
Management
OFFICE LOCATION:
1830-B Tillery Place
Raleigh, NC 27604
Telephone: [phone]x351
An Equal Opportunity/Affirmative Action Employer

.1 . . L
NORTH CAROLINA STATE CLEARINGHOUSE
DEPARTMENT OF ADMINISTRATION
INTERGOVERNMENTAL REVIEW
MS MELBA MCGEE
CLEARINGHOUSE COORD•
DENR LEGISLATIVE AFFAIRS
ARCHDALE BLDG - MSC # 1601
RALEIGH NC
REVIEW DISTRIBUTION
CC&PS - DEM, NFIP
CENTRALINA COG
DENR LEGISLATIVE AFFAIRS
DEPT OF CUL RESOURCES
DEPT 'OF TRANSPORTATION
cO
r.
CO
tP
PROJECT INFORMATION •
APPLICANT: DEnr, Water Quality
TYPE: State Environmental Policy Act
ERD: Environmental Assessment/Finding
STATE NUMBER:
DATE RECEIVED:
AGENCY RESPONSE:
REVIEW CLOSED:
of No Significant Impact
05-E--4300-0040
08/11/2004
09/08/2004
09/13/2004
DESC: Expansion of the 12 Mile Creek Wastewater Treatment Plant in Waxhall , N.C.
CROSS-REFERENCE NUMBER: 03-E-4300-0009
The attached project has been submitted to the N. C. State Clearinghouse for
intergovernmental review. Please review and submit your response by the above
indicated date to 1301 Mail Service Center, Raleigh NC 27699-1301.
If additional review time is needed, please contact this office at [phone].
AS A RES LT F THIS REVIEW THE FOLLOWING IS SUBMITTED:
NO COMMENT
SIGNED BY:
DATE:
COMMENTS ATTACHED
1-