NC0085359_Engineering Alternatives Analysis_20030320

NPDES DOCUHENT SCANNIN` COVER SHEET
NPDES Permit:
NC0085839
Twelve Mile Creek WWTP
Document Type:
Permit Issuance
Wasteload Allocation
Authorization to Construct (AtC)
Permit Modification
Complete File - Historical
Engineering Alternatives (EAA)
Correspondence
Owner Name Change
Instream Assessment (67b)
Speculative Limits
Environmental Assessment (EA)
Document Date:
March 20, 2003
Thus document is prirzted on reuse paper - ignore any
content on the rezrerse side

m
MCKIM&CREED?3°k r,
March 20, 2003
Mr. David A. Goodrich
NPDES Supervisor
NC Dept. of Environment and Natural Resources
Division of Water Quality
1617 Mail Service Center
Raleigh, NC 27699-1617
I ` ) r- 00771.0023 (42)
RE: Engineering Alternatives Analysis
Union County Twelve Mile Creek Wastewater Treatment Plant Expansion
NPDES Permit NC0085359
Dear Mr. Goodrich,
Enclosed for your review are five copies of the Engineering Alternatives Analysis which
evaluates alternatives to provide additional capacity in Union County's Twelve Mile
Creek Sewer Service Basin. Union County's Twelve Mile Creek Wastewater Treatment
Plant, which is permitted for a flow of 2.5 mgd, serves this basin. The facility is currently
operating at about 40-50% of its design capacity. However, an analysis of growth
trends in western Union County suggests that the facility will require expansion by
around the end of the year 2004.
We have evaluated three alternatives to provide the additional capacity: expanding
the existing facility; constructing a land application system; or discharging into the
Charlotte -Mecklenburg Utility system at Six Mile Creek. Our analysis confirms that the
most cost effective alternative and the one with the lowest capital cost is to expand
the existing facility.
A description of the existing facilities, wastewater flow projections, and the evaluation
of alternatives is covered in the attached report. We recommend that Union County
increase the capacity of the Twelve Mile Creek Wastewater Treatment Facility by re -
rating the existing plant to 3 mgd, and doubling the size of the facility to a capacity of
6 mgd. This capacity is expected to meet the needs of this basin for the next ten (10)
years.
In addition to the Engineering Alternatives Analysis, we are also preparing an
Environmental Assessment (EA) document covering this project. This document will be
2300 SARDIS RD. N., SUITE A, CHARLOTTE, NORTH CAROLINA 28227
TEL [phone] FAX [phone] www.mckimcreed.com
AA0002667

submitted shortly for review. In the meanwhile, we request that your staff review the
Engineering Alternatives Analysis. Please contact our office at 704-841-2588 to discuss
any issues that arise.
We appreciate the cooperation and guidance you have provided thus far as we
assist the County with the project permitting.
Respectfully submitted,
McKIM & CREED, PA
William S. Riddick, Jr., PE
Senior Project Manager
pc: Mr. Jon Dyer, Director, Union County Public Works
Mr. Mark Tye, Assistant Director, Union County Public Works
*fr/McKEM&CREED

Twelve /vile Creek
Sewer Service Basin
ENGINEERING ALTERNATIVES ANALYSIS (EAA)
TWELVE MILE CREEK
WWTP EXPANSION
‘' McKNI&CREED

Twelve Mile Creek
Sewer Service Basin
ENGINEERING ALTERNATIVES ANALYSIS (EAA)
TWELVE MILE CREEK
WWTP EXPANSION
ft7/&A3
McKim & Creed, PA
2300 Sardis Road North, Suite A
Charlotte, NC 28227

Table of Contents
Engineering Alternatives Analysis (EAA)
Twelve Mile Creek WWTP Expansion
Section: Paqe:
Section 1 - General Information 1
Proposed Action 1
Sewer Service Areas/Facilities 1
Wastewater Flow Projections 4
Section 2 - Wastewater Disposal Alternatives 9
Background 9
Re -rating the Twelve Mile Creek WWTP 9
Alternatives 10
Section 3 - Evaluation of Alternatives 12
Background 12
Expand the Existing Twelve Mile Creek WWTP 12
Construct Land Application System 13
Discharge to the Charlotte -Mecklenburg Utility System 14
Evaluation of Alternatives 15
Selected Alternative 17
Section 4 - Program Implementation 18
Proposed Action 18
Recommended Facility Improvements 18
Program Implementation 18

SECTION 1 - GENERAL INFORMATION
A. PROPOSED ACTION
The proposed action for which this Engineering Alternatives Analysis (EAA) has been
prepared will increase the available capacity of wastewater treatment/disposal facilities
serving the Twelve Mile Creek sewer service area in western Union County from 2.5 MGD
to 6.0 MGD.
1. Facility Name: Twelve Mile Creek WWTP
2. County: Union County, NC
3. Address: 3401 Providence Road South, Waxhaw, NC.
Facility Phone Number: 704-843-9482
4. EAA Prepared by:
McKim & Creed, PA
2300 Sardis Road North, Suite A
Charlotte, NC 28227
Attn: Mr. William S. Riddick, Jr., PE
Phone: [phone]
E-mail: [e-mail]
B. 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. Currently the
Twelve Mile Creek basin is the largest sewer service basin in Union County. These basins
are shown on Figure 1.
1. TWELVE MILE CREEK SEWER SERVICE BASIN
The Twelve Mile Creek drainage basin extends from the 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.
2. 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 Carrousel® 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.
Engineering Altematives Analysis (EAA)
Twelve Mile Creek WWTP Expansion
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fm+
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. A rotary thickener is provided. Solids disposal
is by land application.
In 2001, a 1.0 million gallon (MG) aerated sludge holding tank was added. This
expansion, coupled with the exceptional performance of this treatment plant,
demonstrates that the facility is capable of operating at flows of 3.0 MGD or
greater. The County expects to_formally apply to hav_e the facility_re.:p rmitted
for a flow of 3.0 MGD in the immediate future. Figures3, 4, and 5 illustrate the
foci sc:
l site Ian, site layout, and process herfnat E __
Operating data for fiscal year 2000 - 2001 are compared to the NPDES Permit
Limits in Table 1, and illustrate that the facility consistently meets all operating
parameters.
Table 1
FY 2000 - 2001 Performance Summary
Twelve Mile Creek WWTP
i Parameter
NPDES Limit
j
Actual Value
Flow, MGD
2.50
;
0.925
BOD5, Summer, PPM
I
5.0
•j
0.61
BOD5, Winter, PPM
I
10.0
�
0.64
NH3-N, Summer, PPM
2.0
0.17
NH3-N, Winter, PPM
4.0
0.19
TSS, PPM
30.0
0.04
Total Phosphorous, #/day
20.85*
15.57
Fecal Coliform, per 100 ml
200
8.08
DO, PPM
>_ 6.0
7.93
r•, *Not a Permit Limit until January 1, 2003.
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, even though the facility
operated at about 40% of design for the year 2000/2001. At this time, only limited
data are available on effluent phosphorous. The mass limit of 20.85 #/day is
equal to a concentration value of 1.0 ppm at a flow of 2.5 mgd. For the period
shown in Table 1, the average monthly effluent concentration was 2.02 mg/I, and
ranged from 0.20 to 6.0 mg/I. The facility was not operating to meet the
phosphorous limit during this period, but is capable of meeting this limit.
Engineering Alternatives Analysis (EAA)
Twelve Mile Creek WWTP Expansion
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1101
3. INTERCEPTORS, PUMP STATIONS, AND FORCE MAINS
A number of interceptor sewers, pump stations, and force mains have been
constructed to convey wastewater into the treatment plant. These are shown on
Figure 2 and described below.
a. 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.
b. 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
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.
1.9
c. 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 enters the Fincher Road pump
cm' station, which pumps to Price Mill Creek (a trunk sewer project which will
allow this station to be decommissioned is scheduled for construction in
2003) .
rim
d. Phase I of the West Fork Twelve Mile Creek interceptor was completed in
2001. This line consists of 4,500 feet of 42-inch pipe up the 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. This line was also
completed in 2001.
e. In 1999, a 10-inch PVC sewer was constructed along Still House Branch
from the treatment plant upstream to Newtown Road.
f. 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.
flol g. 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.
h. A 30-, 24-, 18-, and 15-inch line is currently under construction on Little
Twelve Mile Creek. This line will be completed in early 2003, and will
extend sewer service to NC 75 and areas around Mineral Springs.
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i. The County recently awarded a construction contract for the Blythe
Creek line, which will expand service to Waxhaw.
There are two pending construction projects along the East and West
Forks of Twelve Mile Creek. A 12- and 15-inch line will extend along Davis
Mine Branch from Fincher Road to Hawfield Lane. This line will eliminate
the Fincher Road and Hunters Pointe pump stations. Another will involve a
pump station located above Forest Lawn Road, and an 18- to 12-inch
trunk line to the existing Spring Hill Pump Station. This project will eliminate
two existing pump stations, and provide service to two planned residential
developments and a new elementary school.
There are several pumping stations in the Twelve Mile Creek service area that
currently convey wastewaters into existing components of the interceptor system.
These are described below.
a. 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.
b. 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.
c. A new 1,063 gpm pump station is under construction on the West Fork
Twelve Mile Creek. This station will serve two planned subdivisions with a
total of about 1,058 connections and an existing 472± customers
connected to two pump stations which are to be abandoned.
4. 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 will divert up to 1.2 MGD from this basin into the
Twelve Mile Creek basin on an interim basis to meet capacity needs in the
Crooked Creek area of Union County. It is expected that this diversion will be
required for up to ten years, or whenever the planned regional wastewater
facility to serve northwest Union County becomes a reality. 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.
C. WASTEWATER FLOW PROJECTIONS
In 1999, Union County prepared an update of the Master Water and Sewer System
Master Plan. 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
Engineering Alternatives Analysis (EAA)
Twelve Mile Creek WWTP Expansion
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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. In addition, growth of new "water only
accounts" in western Union County in the late 1990's was also considered. This growth
from 1995 to 1999 occurred at an annualized rate of 4.7%.
0.,
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
rim County as the guide to planning for water/sewer service needs.
The overall population projections and their distribution by census tract were used to
fir determine wastewater flows for the Twelve Mile Creek Sewer Service area. The following
assumptions were utilized:
1.1 1. For existing sewered areas, 100% of new growth would be served by the
wastewater system.
2. For currently unsewered areas, no wastewater flows would be generated until
trunk lines were built. Growth occurring up to that time will not be served; but
100% of growth thereafter will be served.
3. 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.
4. 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 on 360 gallons per
household per day. The lower numbers are more representative of actual water
use in Union County.
Appendix A presents a summary of the population projections for the Twelve Mile Creek
basin.
rwl As a part of the Master Sewer Plan Development, phasing of trunk sewer construction in
each basin was discussed in several public/stakeholder work sessions. A recommended
plan of construction was then prepared which included the following for the Twelve Mile
Creek area:
1. Phase 2002 - 2005
a. Construct Little Twelve Mile Creek Trunk Sewer. (Completed).
b. Construct Blythe Creek Trunk Sewer towards the Town of Waxhaw.
(Awarded).
c. Construct Davis Mine Creek trunk sewer and decommission two (2)
existing pump stations. (Proposed for mid-2003).
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At this time the Little Twelve Mile Creek project is nearing completion; bids have
been received for the Blythe Creek sewer; private interests have committed to
build the Davis Mine Creek line in early 2003; and the West Fork Twelve Mile Creek
Trunk Sewer is still planned by 2005.
2. Phase 2005 - 2010
a. Extend the West Fork Twelve Mile Creek line upstream to the Springhill
Pump Station.
b. Construct trunk line along Waxhaw Creek.
mr' c. Construct a trunk line along Keels Creek to NC 84.
d. Extend trunk lines along Mundy's Run, Culvert Branch, and other unnamed
'" I tributaries of the West Fork Twelve Mile Creek towards Mecklenburg
County.
The Culvert Branch line has been completed through private funding. Private
interests are planning to complete the upper third of Project 2a and add a 1,063
gpm pump station to extend service. Construction will begin in early 2003.
Environmental concerns associated with a Federally protected species will
rwl
potentially defer the Waxhaw Creek project for the foreseeable future.
The County capital plan will open essentially all of the Twelve Mile Creek basin to sewer
ron 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 EAA.
Another significant influence on flows directed to the Twelve Mile Creek WWTP is the
status of planning/permitting for a regional wastewater facility at the Goose
Creek/Crooked Creek/Rocky River confluence. 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 B. This facility will divert flow from the Crooked
Creek basin into the Twelve Mile Creek system.
A third 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.
The County is also considering taking over the privately owned Fairfield Plantation WWTP,
which is under an SOC. Flows from these two plants and the sewer service area will be
diverted to the North Fork Crooked Creek system and subsequently Twelve Mile Creek.
Diversions to Twelve Mile Creek will begin in 2003.
Wastewater flows originating in the Crooked and Goose Creek basins (areas currently
served by Union County) have been projected through the year 2010, assuming that no
new significant sewer service area expansions occur before that time. Flows anticipated
to be diverted into the Twelve Mile Creek basin are estimated assuming that the
Crooked Creek WWTP operates at a "base" capacity of 1.5 MGD, or about 80% of its 1.9
MGD NPDES Permit. These projections are tabulated in Appendix A, and summarized in
Table 2.
mai
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Table 2
Wastewater Flow Projections, MGD
Crooked/Goose Creek Basin
Year
2000
Total Flow, MGD Diverted Flow, MGD
2005
2010
1.1697 0
1.8943 0.3943
2.26250 1.1250
In estimating the magnitude of flows diverted, it has been assumed that the Crooked
Creek WWTP would operate at an base flow of 1.5 MGD. Appendix A also includes a
tabulation of the flow to the Twelve Mile Creek WWTP. These estimates reflect the
adopted phasing plan for sewer construction and the diversions from Crooked Creek.
Table 3 summarizes these estimates.
Table 3
Wastewater Flow Projected, MGD
Twelve Mile Creek Basin
Year
2000
2005
Twelve Mile
Creek Flow
Crooked Creek •
Diverted Flow
Total, MGD
0.903 0 0.903
2010
2020
2.435 0.3943 2.8293
4.026
1.1250 5.1510
6.859 0 6.859
Twelve Mile Creek wastewater flows assume the regional facility in northwest Union
County will be available by 2010, allowing diversions from Crooked Creek to be
discontinued at that time.
Trends presented in Appendix A illustrate that Union County must provide a total
treatment capacity of 6.0 MGD by 2005 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
further capacity expansion of 3.0 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. Union County has experienced four (4) consecutive years of unprecedented
Engineering Altematives Analysis (EAA)
Twelve Mile Creek WWTP Expansion
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drought, with rainfall totals well below long term average. Water use has been restricted
in hot months. While the restrictions have been for activities such as lawn watering, it is
likely that conservation has also reduced wastewater discharges. Also, groundwater
levels are at or near historic lows, reducing "normal" I/1 contributions to the sanitary sewer
systems. Summary flow data for the period 1998 to 2001 appear inconsistent with the
growth rates contained in the population growth model. 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 more 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 re-rate/expand the Twelve Mile Creek WWTP to a capacity of 6.0 MGD, or
alternately re -rate the existing plant to 3.0 MGD and provide an additional 3.0 MGD in
capacity either through expansion of existing contracts with Charlotte -Mecklenburg
Utilities, or by other means as discussed in the following sections.
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
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.
Engineering Altematives Analysis (EAA)
Twelve Mile Creek WWTP Expansion
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fINA
SECTION 2 - WASTEWATER DISPOSAL ALTERNATIVES
A. 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
Mal 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 has two (2) major new requirements:
1. Establishes 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.
2. Establishes 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
f"' total phosphorous occurs in the process, even though plant operations have not focused
specifically on maximizing phosphorous reduction. Union County does not anticipate
undue problems meeting the current TMDL for phosphorous using the BNR process plus
rawn chemical treatment, if necessary.
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.
B. RE -RATING THE TWELVE MILE CREEK WWTP
As a part of the strategy to provide additional capacity, Union County plans to 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:
1. The Carrousel® oxidation ditches can meet design requirements at a projected
flow of 3.1 MGD.
Put
Engineering Alternatives Analysis (EAA)
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1.9
2. 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.
ism C. ALTERNATIVES
Wastewater flow projections presented in Section 1 C, Table 2 show that by 2010 the
pp)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.
mei
2. Construct a land -based spray irrigation system with a rated capacity of 3.0 MGD.
Expand the system by 3.0 MGD in 2014.
Alternatives evaluated herein are based on continued operation of the existing Twelve
Mile Creek facility at a re -rated capacity of 3.0 MGD. Additional capacity will be
A., provided in 3.0 MGD increments by one of the three options listed below:
1. Expand the existing surface discharge facility from 3.0 to 6.0 MGD by 2004, and
from 6.0 to 9.0 MGD by 2014.
3. Discharge 3.0 MGD into the Charlotte -Mecklenburg Utilities system on Six Mile
Creek. Increase the allowable discharge to 6.0 mgd by 2014.
Each of these options is discussed in the following sections.
The evaluation of alternatives to provide an additional 3.0 MGD in capacity considers
fool the facilitycapital cost, operations and maintenance to identifythe "present -value -of -
cost"
p p of each option.
1. Expand the existing Twelve Mile Creek WWTP in 3.0 MGD increments.
This alternative will provide for the following modifications/additions to the existing
part treatment plant:
a. 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.
b. A new 3.0 MGD "liquid process" line consisting of parallel Carrousel®
oxidation ditches, new parallel 70-foot diameter secondary clarifiers, new
recycle/ waste sludge pumping, two (2) more effluent filters, parallel UV
disinfection system, and related process piping.
Engineering Altematives Analysis (EAA)
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Rig
Ing
Awl
cMI
c. New 1.0 MG aerobic sludge digester with diffusers and new blower
building.
d. New 750 kW emergency generator with primary switchgear for the liquid
process facilities, and all other site electrical and instrumentation.
2. Construct land -based treatment system.
a. 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 in 3.0 MGD increments, as noted.
b. New headworks with fine screens and odor control would be constructed
ahead of the existing influent pump station. A new influent station and
1.9
force main will be constructed to convey wastewaters to a remote
stabilization lagoon site.
c. Construct stabilized waste holding basin(s) and pumping facilities to
individual land treatment sites.
rim d. Construct land stabilization sites consisting of piping and fixed spray
nozzles.
Mot
3. 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
flEr' 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. Required facilities include:
a. Construct new headworks with fine screening and odor control, and a
new influent pump station dedicated to pumping flow to the Six Mile
p.mCreek trunk sewer. The station would be rated for an average daily flow
of 3.0 MGD, and be expandable for future flows.
b. 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.
c. 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.
PIM
Each of these alternatives will provide a total treatment capacity of 6.0 MGD by
2004, and 9.0 MGD by 2014.
Engineering Altematives Analysis (EAA)
Twelve Mile Creek WWTP Expansion
Page 11

rw
SECTION 3 - EVALUATION OF ALTERNATIVES
A. BACKGROUND
Alternatives discussed in Section 2 will each meet projected wastewater capacity needs
of 6.0 MGD by the year 2004, and 9.0 MGD by 2014. The alternatives have been
evaluated on the basis of present worth or present value of cost in accordance with
prescribed criteria.
Psi
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 (i = 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
'u, Alternatives," published by NCDENR, June 9, 2000.
Each alternative is further described in the following sections. Capital cost estimates,
r"' along with applicable operations and maintenance estimates for each alternative have
been prepared.
1.1 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 alternative,
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.
B. 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.
Pul 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 Carrousel® 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
ton 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 two (2) "fine" mechanical screens and space for a future
unit.
2. Upgrade influent pump station by replacing three (3) existing pumps with three
eval (3) new 280 Hp units, sized so that any two pumps can meet peak capacity of 2.5
Put
Engineering Altematives Analysis (EAA)
Twelve Mile Creek WWTP Expansion
Page 12

(6.0 MGD) or 15 MGD. One existing 88 Hp pump will be kept for low flow
conditions.
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 to meet
pumping needs.
5. Provide two (2) additional Carrousel® oxidation tanks, two (2) additional 70-foot
diameter 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 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 2014. 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 2004. The unit
treatment charge is estimated at $0.84/1000 gallons by 2014, adjusted for increased flow
but not inflation of costs.
The 20-year present worth of this alternate is approximately $33.8 million.
C. 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:
1. The Waxhaw site was permitted at a net 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.
2. 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.
Engineering Alternatives Analysis (EAA)
Twelve Mile Creek WWTP Expansion
Page 13

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.
Considering the above, the following facilities are required for a parallel land application
system:
1. New headworks with fine mechanical screens and space for a future unit.
2. New influent pump station with standby generator to pump from the Twelve Mile
Creek site to the lagoon/spray site.
3. Odor control system for headworks.
4. Approximately ten miles of 24-inch force main.
5. Waste stabilization and treated effluent storage system.
6. Effluent disinfection system.
7. 1,000 acres of active sprayfields with piping, sprinklers, and controls; and an
additional 1,000 acres for buffers, etc.
8. 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 2014, a further expansion will be required at an estimated cost of $14.9 Million. Key
rwl
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.
D. 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
r., 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 $1,140,000, bringing the total estimated
capital cost to $3,955,000 per million gallons of capacity.
Engineering Altematives Analysis (EAA)
Twelve Mile Creek WWTP Expansion
Page 14

Facilities required to provide 3.0 mgd of capacity include:
1. New headworks with fine mechanical screens and space for a future unit.
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 $11.865 Million.
The total project cost to provide the facilities for 3.0 MGD of capacity are estimated at
approximately $22.9 Million. This includes current and anticipated capital charges to
CMU.
By 2014 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 $5.12 million/MGD. The total cost per MGD to expand from 6.0
to 9.0 MGD, including the cost in the Six Mile Creek transmission and pumping system,
would be $6,885,000/MGD. The total of the expansion to 9.0 mgd is estimated at a
project cost of $21.5 Million. The 20-year present worth of this alternative is $47.7 Million.
E. 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:
1. 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 2014, as flows increase, the treatment cost will be reduced to
about $0.70 per 1,000 gallons.
2. 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.
3. 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 $11.9 Million. The phase 2 capital cost
Engineering Alternatives Analysis (EAA)
Twelve Mile Creek WWTP Expansion
Page 15

estimate, including capacity charges, is $21.5 Million. The current unit treatment
charge is $0.66 per 1,000 gallons.
The capital cost of each alternate is summarized in Table 4.
Table 4
Estimated Capital Costs
Alternate Phase 1 Phase 2 Total
1. Expand Twelve Mile Creek WWTP $12,289,000
2. Land Application
3. Pump to CMU
$15,877,000 $28,166,000
$70,755,000 $14,934,000 $85,689,000
$22,924,000 $21,483,000 $44,470,000
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 present worth of these alternatives is shown in
Table 5.
Table 5
20-Year Present Value of Costs
Alternate Amount
1. Expand Twelve Mile Creek WWTP
$33,758,000
2. Land Application $78,897,000
3. Pump to CMUD
The present value 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 present value. Land
application has the highest present value 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 the capital and present worth costs between plant expansion and
pumping into the CMUD system. Much of the difference is associated with pumping from
the Twelve Mile Creek site into the CMUD Six Mile Creek system near Marvin.
Based on the significant difference in the present value of each alternative, minor
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.
Engineering Alternatives Analysis (EAA)
Twelve Mile Creek WWTP Expansion
Page 16

F. 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
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)
Carrousel® A20 oxidation ditch systems, which include a fermentation zone, an
anoxic zone, and an aerobic oxidation ditch. The configuration oaf the
Carrousel® reactors 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
Carrousel® reactors 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.
Engineering Alternatives Analysis (EAA)
Twelve Mile Creek WWTP Expansion
Page 17

SECTION 4 - PROGRAM IMPLEMENTATION
A. 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 2004. 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 treatment capacity
from 2.5 mgd to 6.0 mgd by re -rating the existing facility and adding 3.0 mgd of
additional capacity.
B. 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 $86.7 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.
C. PROGRAM IMPLEMENTATION
Re -rating and expansion of the Twelve Mile Creek involves several key initiatives
including:
1. Review of the existing facility and completion of a Re -rating Study. This task is
completed.
2. Obtain an NPDES Permit for the proposed facility. This will involve completion of
this Engineering Alternatives Analysis (EAA) and an environmental assessment
(EA).
3. Prepare Engineering design documents and obtain construction permits.
4. Construct improvements and receive authorization to operate at flows above 2.5
mgd.
Union County is moving forward on each of these critical steps with a target of placing
the expanded facility online in 2004.
Engineering Alternatives Analysis (EAA)
Twelve Mile Creek WWTP Expansion
Page 18

APPENDIX A
WASTEWATER FLOW PROJECTIONS
1 - Crooked Creek Diversion
2 - Twelve Mile Creek
MCKIM & CREED

l l ] I 1 1 1 1 1 1 1 1 1 1 1 1 1
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 VVVVTP 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 VVVVTP Base Flow
1.5000
North Fork Crooked Creek Diverted FI,
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 Fairfield Plantation •
0.1000
SUBTOTAL:
25250
2.6250
Crooked Creek WV TP Base Flow
1.5000
North 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

l l l 1 i i l 1 1 l 1 l 1 1 l I I l l
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
TMC 10
Waxhaw-Blythe Creek (two schools)
2943
0.2943
2800
0.3000
TMC 11
Little TMC
2751
0.2751
TMC 12
Creek
312
0.0312
100
0.0100
TMC 13
Mineral Springs
784
0.0784
Total Combined School Flow
0.0060
0.0600
Total - Twelve Mile Creek Basin
30893
3.0953
7830
0.9030
North Fork Crooked Creek Diverted Flow
Projected Twelve Mile Creek WWTP Flow
0.0000
0.9030

Twelve Mile Creek Service Area
Population Served and Wastewater Flows
Sewer Basin/Description
2005 Potential
1999 - 2005 Growth
2005 Actual
Population
Flow (mgd)
Population
Flow (mgd)
Population
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
Mundy's 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
1907
0.1907
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 WWTP Flow
0.3943
2.8288

Twelve Mile Creek Service Area
Population Served and Wastewater Flows
Sewer Basin/Description
2010 Potential
2005 - 2010 Growth
201.0 Actual
Population
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
0.1114
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
Little TMC
6565
0.6565
1907
0.1907
.3814
0.3814
TMC 12
Creek
1073
0.1073
381
0.03805
861
0.0861
TMC 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
North Fork Crooked Creek Diverted Flow
Projected Twelve Mile Creek WWTP Flow
1.1250
5.1510

Twelve Mile Creek Service Area
Population Served and Wastewater Flows
Sewer Basin/Description
2020 Potential
2010 -2020 Growth
2020 Actual
Population
Flow (mgd)
Population
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
0.5802
638
0.0638
4217
0.4217
TMC 4
Lower Price Mill Creek (1 School)
4120
0.4120
1843
0.1843
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 1
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
9.1652
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
1 - Stream Flow Data
2 - NPDES Permit Speculative Limits

PEI
771 eZ>Z3
United States Department of the Interior
U.S. GEOLOGICAL SURVEY
3916 Sunset Ridge Road
Raleigh, North Carolina 27607
July 15, 2002
Mr. W.S. 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 low -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 ft3ls/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 Slate 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 ft3ls, or a 30Q2 yield of 0.0412 ft3/s/mi2.
You identified the actual location 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 downstream reach indicates that no tributaries enter into Twelve Mile Creek between the station
and the discharge point. Thus, the low -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 271, 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 Weave
Hydrologist
J. Curtis Weaver
Hydrologist
[phone] • FAX [phone]

,SUMMARY OF LOW -FLOW ESTIMATES IN RESPONSE TO REOUEST
REQUEST NO: 91613 SITE NO: 01 DATE: 07/15/2002
fon 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°5708" LONGITUDE: 80°45'21"
QUANDRANGLE NAME AND NUMBER: Catawba NE 1H-15-NE1
mig
COUNTY CODE: Union f 1791 STATE CODE: NC f371 DISTRICT CODE: NC F371
�► 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 ft3/s see note [A]
]
ANNUAL 7Q10 MINIMUM FLOW: 0.0013 ft/slmi2 0.1 ft3/s see note U
ANNUAL 30Q2 MINIMUM FLOW: 0.0412 ft3/s/mi2 3.2 ft3/s see note U
WINTER 7Q10 MINIMUM FLOW: 0.0200 •2 1.5 A
ft3/s/mi ft3/s see note U
ANNUAL 7Q2 MINIMUM FLOW: 0.0183 ft/s/mi2 1.4 ft3/s see note
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
Art 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.
0.1 [E] See remarks.
These data are considered provisional and subject to revision pending approval by the Director, USGS.
1.1
REMARKS:
• Low -flow estimates based on discharge records collected at gaging station during 1961-2000 climatic years
pig (12-month period from April 1 through March 31 and designated by the year in which the period begins,
used in low -flow analyses at continuous -record gaging stations)
• Requested by Mr. Sid Riddick, McKim & Creed Engineers
ENTERED BY: JCW FEE CHARGED: $ 150

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. Jon C. Dyer, P.E., Director
Union County Public Works Department
400 North Church St.
ram
Monroe, North Carolina 28112-4804
U C PUBLIC WORKS 7042964232 06/20/22 06:13pm P. 002
7 i i 1c Z 3 S)
Agi4;761,
NCDENR
Subject: Union County -Twelve Mile Creek WWTP
Speculative Limits for Expansion
NPDES Permit No. NC0085359
Union County
Dear Mr.•Dyer:
.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' for,6:0'MGD at this.tune.: These limits should be considered
very preliminary, as there .are a number of pending scions and .communications that may
influence your project. Twelve Mile Creek eventually flows into the Caawba River after
�► crossing the South Carolina state line. Any finalized 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 an•Environmental Assessment (EA) when
•wastteflows exceed or equal 0.5 MGD. If the EA demonstrates that the project may result in a
significant adverse effect•on the quality.of the environment,.an Environmental Impact Statement
(EIS) is required: • DWQ will not accept a permit application for a project 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 No Significant Impact (FONSI) has been sent to the State
Clearinghouse for review and comment or an EIS has_been approved. The Division of Water
Quatity's'Planning Branch can provide further information regarding the requirements of the
N.C. Environmental Policy Act. Please.contact Todd Kennedy ofthe DWQ Planning Branch at
(9.19) 733-5083.ext. 555'if you have questions: on this subject:• '
1617 Mail Senilce Center, Raleigh, North Carolina 27699-1617 Telephone [phone] FAX [phone]
An Equal Opportunity Affirmative Action Employer. Internet: http:tih2o.enr.state.nc.usl

pm U C PUBLIC WORKS 7042964232 06/20/02 06:19pm 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 altematives, 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
(.4 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 that_...:.':.
the County request actual flow estimations from the United States Geological Survey to ensure
1.9 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. lnstrearn water .
quality data indicated that there were dissolved oxygen levels below the 5.0 mg/1 standard both
above and below the Twelve Mile Creek WWTP discharge. There were data that showed
Pm, 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
MOP 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 WWTP on water quality in the receiving stream.
f,., 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/1 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.

nn
U C PUBLIC WORKS 7042964232 06/20/02 06:13pm 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,
0,4
10-c-- David A. Goodrich
NPDES Unit Supervisor
rim
cc: Mooresville Regional Office/Rex Gleason
Bobby Blowe, Construction Grants
Pot Central Files
NPDES Permit File
Jeff deBessonet, Bureau of Water DHEC, 2600 Bull St., Columbia SC 29201 .
frit
tml

U C PUBLIC WORKS
7042964232 06/20/02 06:13pm P. 00S
`'' Page 4
ran
Twelve Mile Creek WWTP Speculative Limits
A. SPECULATIVE EFFLUENT LIMITATIONS AND MONITORING
REQUIREMENTS - UNION CO. — TWELVE MILE CREEK WWTP
'1► ''
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r
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
BOD, 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
— March 30)
2.0 mg/L
Daily
Composite
Effluent
Dissolved Oxygen3
.
Daily =
Grab
Effluent ,Upstream,
Downstream
Fecal Coliform
(geometric mean) •\
200 / 100
ml
400 / 100
ml
Daily
Grab :
Effluent , Upstream,
Downstream
pH4
Daily
Grab
Effluent
Conductivity
' .
Daily
Grab
Effluent .
Total Phosphorus
Monthly Average: 41.7 Ibs/day
12 Month Average: 20.9 Ibs/day
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
mit Notes:
1. Influent, Effluent, Upstream 50 feet above the outran; Downstream sampling points D1+D2; D1- One
quarter mile below the outran, before confluence with the first tributary; D2 - Downstream at NCSR
,R 1301
2. The monthly average effluent HODS 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 less than 6.0 mg/1.
4. The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units.
S. Chronic Toxicity (Ceriodaphnia) P/F at 90%; February, May, August, and November.

APPENDIX C
COST ESTIMATES
Alt. 1 - Expand Twelve Mile Creek
Alt. 2 - Land Application
Alt. 3 - Pump to CMUD
Present Worth Summary
4°,?McKIN4&CREED

Owl
Fog
OINEI
MEI
I�l
101110
faro
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 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
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

1 I J 1 ] 1 ] 1 4 l 1 1 1 1 1 1 1
ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
OPINION OF PROBABLE COST
ALTERNATIVE 1 - PHASE 1
EXPAND TREATMENT PLANT TO 6.0 MGD
YEAR 2004
ITEM
DESCRIPTION
UNIT
ESTIMATED
QUANTITY
UNIT PRICE
TOTAL PRICE
SALVAGE VALUE
HEADWORKS W/ ODOR
CONTROL LS 1
$1,000,000
$1,000,000
N/A
$500,000
UPGRADE INFLUENT PS LS 1
$600,000
$600,000
N/A
$0
OXIDATION DITCHES LS 1
$2,000,000
$2,000,000
$1,500,000
CLARIFIERS LS 2
$750,000
$1,500,000
$1,125,000
RECYCLE/WASTE PUMP LS 1
$400,000
$400,000
N/A
$0
1 MG DIGESTER W/
BLOWERS LS 1
$1,000,000
$1,000,000
N/A
$0
FILTERS & AIR COMP. LS 1
$750,000
$750,000
N/A
$375,000
UV DISINFECTION LS 1
$605,000
$605,000
N/A
$302,500
BLOW BUILDING LS 1
$50,000
$50,000
$25,000
ELECTRICAL LS 1
$1,000,000
$1,000,000
N/A
$500,000
SITE WORK PIPING LS 1
$1,500,000
$1,500,000
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
$12,289,000
ENGINEERING NEWS RECORD CCI = 6589

l 1 1 1 I l ] 1 I I I 1 I I l l 1 1 l
ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
OPINION OF PROBABLE COST
ALTERNATIVE 1 - PHASE 2
EXPAND TREATMENT PLANT TO 9.0 MGD
YEAR 2014
ITEM
DESCRIPTION
UNIT
ESTIMATED
QUANTITY
UNIT PRICE
TOTAL PRICE
SALVAGE VALUE
NEW PARALLEL INFLUENT
PUMP STATION LS 1
$1,000,000
$1,000,000
$375,000
ADDITIONAL SCREENING LS 1
$250,000
$250,000
$125,000
ADDITIONAL GRIT REMOVAL LS 1
$500,000
$500,000
$250,000
OXIDATION DITCHES LS 1
$2,000,000
$2,000,000
$1,500,000
CLARIFIERS LS 2
$750,000
$1,500,000
$1,125,000
RECYCLE/WASTE PUMP LS 1
$400,000
$400,000
$100,000
1.0 MG AEROBIC DIGESTER
W/ BLOWERS LS 1
$1,000,000
1000000
$625,000
FILTERS LS 2
$750,000
$1,500,000
$750,000
UV DISINFECTION LS 1
$605,000
$605,000
$302,500
ELECTRICAL LS 1
$1,000,000
$1,000,000
$500,000
SITE WORK PIPING LS 1
$1,500,000
$1,500,000
$750,000
NEW INPLANT PUMP
STATION LS 1
$250,000
$250,000
$93,750
TOTAL
$6,496,250
SUB -TOTAL
$11,505,000
CONTINGENCY - 20%
$2,301,000
TOTAL CONST. COST
$13,806,000
ENGR. & ADMIN. - 15%
$2,070,900
PROJECT TOTAL
$15,877,000
ENGINEERING NEWS RECORD CCI = 6589

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
PRESENT WORTH ANALYSIS
LAND APPLICATION - ALTERNATE 2
DISCOUNT RATE 6.125%
TOTAL COST I PRESENT WORTH
PHASE I - 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

1 1 1 3 1 1 1 1 1 1 1 1 1 1 1 1 1 1 l
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 LS 1
$1,000,000
$1,000,000
$500,000
INFLUENT PUMP STATION LS 1
$500,000
$500,000
$187,500
FORCE MAIN 30" DIA. LF 52,800
$150
$7,920,000
$6,336,000
SPRAY FIELD PIPING AC 1,000
$3,025
$3,025,000
$1,512,500
EROSION CONTROL LS 1
$175,000
$175,000
N/A
$0
LAGOON -145 AC LS 145
$38,381
$5,565,245
$2,782,623
FENCING LF 12,500
$15
$187,500
N/A
$0
LAB CONTROL BUILDING LS 1
$390,830
$390,830
N/A
$0
ELECTRICAL LS 1
$363,000
$363,000
N/A
$0
EFF. PUMPING LS 1
$363,000
$363,000
N/A
$0
MONITORING WELLS LS 1
$145,000
$145,000
N/A
$0
CLEARING AC 2,200
$250
$550,000
N/A
$0
SUB -TOTAL
$20,184,575
CONTINGENCY - 20% ..
$4,036,915
TOTAL CONST. COST
$24,221,490
ENGR. & ADMIN. - 15%
$3,633,224
SUB -TOTAL
$27,854,714
IRRIGATION SITE - 4000 AC © $ 10,000/AC
$40,000,000
$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

I I I I I 1 I 1 l I I I 1 1 l I I l 1
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
MODIFICATIONS LS 1
$500,000
$500,000
$187,500
FORCE MAIN 30" DIA. LF 0
$0
$0
N/A
$0
SPRAY FIELD PIPING AC 1,000
$3,025
$3,025,000
N/A
$0
EROSION CONTROL LS • 1
$175,000
$175,000
N/A
$0
LAGOON - TO 290 AC LS 145
$38,381
$5,565,245
N/A
$2,782,623
FENCING LF 9000
$15
$135,000
N/A
$0
LAB CONTROL BUILDING LS 1
$0
$0
N/A
$0
ELECTRICAL LS 1
$363,000
$363,000
N/A
$0
EFF. PUMPING LS • 1
$363,000
$363,000
N/A
$0
MONITORING WELLS LS 1
$145,000
$145,000
N/A
$0
CLEARING AC 2,200
$250
$550,000
N/A
$0
!SUB
-TOTAL
$10,821,245
CONTINGENCY - 20%
$2,164,249
TOTAL CONST. COST
$12,985,494
ENGR. & ADMIN. - 15%
$1,947,824
,PROJECT TOTAL
$14,934,000
TOTAL
$2,970,123
Source: EPA MANUAL "COST OF LAND TREATMENT SYSTEM", 430/9-75-003-1979

4
1M
furl
coM
fool
CoM
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 l - 2004
$11,059,000
$11,865,000
$22,924,000
PHASE II - 2014
$828,000
$20,655,000
$11,855,000
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
$30,320,800
$9,234,000
TOTAL =
$47,703,000
*COST INFORMATION OBTAINED FROM CMUD
O&M Present Worth CALCS
YEAR 1
$930,782
YEAR 10
YEAR 20
$2,335,772
$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
TOTAL FOR 20 YR
PW BACK TO YEAR 1
$10,764,872
$22,158,1791

l l l ) I 1 l l l 1 1 1 1 1 l l 1 l 1
ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
OPINION OF PROBABLE 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
LS 1
$500,000
$500,000
$187,500
HEADWORKS W/ ODOR
CONTROL
LS 1
$1,000,000
$1,000,000
$500,000
30" FORCE MAIN
LF 34,000
$150
$5,100,000
$4,080,000
36" GRAVITY SEWER
LF 5,000
$180
$900,000
$720,000
30" BORE
LF 250
$400
$100,000
N/A
$0
4' MANHOLES
EA 25
$2,200
$55,000
$44,000
INTERCONNECTIONS
EA 1
$6,100
$6,100
N/A
$0
EROSION CONTROL
LS 1
$58,600
$58,600
N/A
$0
SEEDING & CLEANUP
LS 1
$18,300
$18,300
N/A
$0
ELECTRICAL
LS 1
$275,000
$275,000
N/A
$0
SUB -TOTAL
$8,013,000
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 VW TP
a) BASE CAPACITY 3.0 MGD @
b) MODERNIZATION RELIABILITY 3.0 MGD ©
$1,050,000
$1,140,000
$3,150,000
$3,420,000
$2,362,500
$2,565,000
SUB -TOTAL - CMUD CAPITAL CARGES
TOTAL PHASE I CAPITAL COST
$11,865,000
$22,924,000
TOTAL SV $14,642,050

1 1 1 1 1 4 1 1 M M M M M M 1 1 1 I 1
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 LF 0
$150
$0
N/A
$0
12,150 GPM PUMP STATION LS 1
$500,000
$500,000
$187,500
36" GRAVITY SEWER LF 0
$180
$0
N/A
$0
30" BORE LF 0
$400
$0
N/A
$0
4' MANHOLES EA 0
$2,200
$0
N/A
$0
INTERCONNECTIONS EA 0
$6,100
$0
N/A
$0
EROSION CONTROL LS 0
$58,600
$0
N/A
$0
SEEDING & CLEANUP LS 0
$18,300
$0
N/A
$0
ELECTRICAL LS 1
$100.000
$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 VWVTP 3/16x
$81,920,000
$15,360,000
$11,520,000
SUB -TOTAL - CMUD CAPITAL CARGES
TOTAL PHASE I CAPITAL COST
$20,655,000
$21,483,000
'
TOTAL
$15,678,750

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
PHASE 1
CAPITAL
PHASE 2
CAPITAL
PRESENT WORTH
O&M
2004
O&M
2014
O&M
2024
O&M
PRESENT WORTH
SALVAGE
VALUE
PRESENT WORTH
TOTAL
PRESENT WORTH
ALTERNATE 1 - EXPAND PLANT
$12,289,000
$8,762,000
$647,500
$1,535,500
$2,867,500
$16,232,000
-$3,525,000
$33,758,000
ALTERNATE 2 - LAND APPLICATION
$70,755,000
$8,241,000
$820,000
$1,845,000
$2,136,000
$17,317,000
-$17,416,000
$78,897,000
ALTERNATE 3 - PUMP TO CMUD
$22,924,000
$11,855,000
$931,000
$2,336,000
$3,077,000
$22,158,000
-$9,234,000
$47,703,000

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 7.0 MGD
$14,934,000
ALTERNATE 3 - PUMP TO CMUD
PHASE 1
CONSTRUCT FM & PIS
$11,059,000
CMUD CAPITAL CHARGES
$11,865,000
TOTAL
$22,924,000
PHASE 2
CONSTRUCT PIS
$828,000
CMUD CAPITAL CHARGES •
$20,655,000
TOTAL
$21,483,000

rn
PEI
151
rat
ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
O & 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
$1,535,500
TREATMENT AT EXISTING PLANT
$647,500
$1,535,500
TOTAL
$930,782
$2,335,772
$3,076,628

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
OPINION OF PROBABLE COST
ALTERNATIVE 2 - O & M - YEAR 2004
LAND APPLICATION PLANT
ITEM
•
UNIT
ESTIMATE .
QUANTITY
UNIT
PRICE
TOTAL
PRICE
SCREENING
LS
1.2
$9,700
$11,640
FACULTATIVE LAGOON
MG
0.4
• $19,920
$7,968
TRANSMISSION
LF
52,800
$0.11
$5,808
STORAGE
MG
12
$26
$312
PUMPING
MG
0.4
$9,150
$3,660
DISTRIBUTION
AC
1800
$66
$118,800
LABORATORY
MG
0.4
$18,910
$7,564
MONITORING WELLS
EA
8
$125
$1,000
SERVICE RDS & FENCING
AC
1800
$7.80
$14,040
CHLORINATION
MGD
0.4
$4,575
$1,830
EXISTING PLANT
$647,500
TOTAL $820,122

ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
OPINION OF PROBABLE COST
ALTERNATIVE 2 - O & M - YEAR 2014
LAND APPLICATION PLANT
ITEM
UNIT
ESTIMATE
UNIT
TOTAL
QUANTITY
PRICE
PRICE
SCREENING
0
co0u_0(.900!“..)0
--12-122<2 LIJ <
1.2
. $9,700
$11,640
FACULTATIVE LAGOON
3
- $19,920
. $59,760
TRANSMISSION
52,800
$0.11
$5,808
STORAGE
12
526
$312
PUMPING
3
$9,150
$27,450
DISTRIBUTION
1800
S66
$118,800
LABORATORY
3
.518,910
$56,730
MONITORING WELLS
6
5125
$750
SERVICE RDS & FENCING
1800
S7.80
$14,040
CHLORINATION
3
$4,575
$13,725
EXISTING PLANT
$ 1,535,500
TOTAL $1,844,515

PM
Mil
ENGINEERING ALTERNATIVES ANALYSIS
UNION COUNTY
OPINION OF PROBABLE COST
ALTERNATIVE 2 - O & M - YEAR 2024
LAND APPLICATION PLANT
ITEM
UNIT
ESTIMATE
UNIT
TOTAL
QUANTITY
PRICE
PRICE
SCREENING
LS
1.2
$9,700
$11,640
FACULTATIVE LAGOON
MG
6
• $19,920
$119,520
TRANSMISSION
LF
52,800
$0.11
$5,808
STORAGE
MG
24
$26
$624
PUMPING
MG
6
$9,150
$54,900
DISTRIBUTION
AC
3600
$66
$237,600
LABORATORY
MG
6
$18,910
$113,460
MONITORING WELLS
EA
10
$125
$1,250
SERVICE RDS & FENCING
AC
3600
$7.80
$28,080
CHLORINATION
MGD
6
$4,575
$27,450
EXISTING PLANT
$1,535,500
TOTAL $2,135,832

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 Flow Sheet - Twelve Mile Creek
6. Projected Wastewater Flow
7. General Soils Map
8. Alternate 1 - Expand WWTP
9. Alternate 2 - Land Application
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
vvMctmvi&citEED

2Q
CROOKED/GOOSE
CLEAR CREEKS
SIXMILE CREEK
Q
EXISTING PUBLIC
PLANT(CAPACITY)
• WASTEWATER PRIVATE
PLANT(CAPACITY)
MONROE BYPASS CORRIDOR
AND ALIGNMENT
BOUINDARYBASIN
- ■ Fairfield
Hunley Plantation (0.07 AIG0
cry Creek (0.25 MOD)
■_'
iINDIA.
A
LANCASTER CO.
Figure 1
EXISTING SEWER SERVICE AREAS
Union County
STAN LY CO.
O
0
Z
0
to
Z
0/00 M KLM

MOM
MINN
MINN
- EXISTING POTW
MONROE BYPASS
CORRIDOR
DRAINAGE BASIN
BOUNDARY
Figure 2
Twelve Mile / Crooked Creek
Sewer Service Areas
v�McK M&CREED

MIR
- EXISTING POTW
MONROE BYPASS
CORRIDOR
DRAINAGE BASIN
BOUNDARY
INTERCEPTOR
SEWER
SEWER
FORCEMAIN
-EXISTING
PUMP STATION
Six Mile
Creek
Z
U U ♦
j JAARS
0 0
z
Figure 3
Existing Facilities
Hunley
Creek WIMrP
(0.23 MGD)
Goose
Creek
Cr. • ked Creek
South Fork
Crooked Creek
vIMcIQM&CREED

v
1 1 2 1 3 1 4 1 5 1 6 1 7 I 8 1 9 1 11) 1 11 1 12 1 13 1 14
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TOTAL i T m C G t*A vou. it. WL
1100020
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-
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570
560
550
340
530
520
(
510
HYDRAULIC PROFILE
110a12OxMfrr. UAL, p i
490
•
•
NFTCIvt&CREm
pl oat • ARO,nCtiS • 9.WORS
UNION COUNTY
NORTH CAROUNA
TWELVE MILE CREEK
WASTEWATER TREATMENT FACILITY
PROCESS SCHEMATIC/HYDRAULIC PROFILE/MASS FLOW
•lbaN
AC
w•n•.
w JIM TL 1
-COWS' C9 rV

FLOW, MGD
10.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
O O
W
z
z
O
Z
W X
X
0
6.0
MGD
2.5
3.0
MGC
MGD
TOTAL F
TWELVE
CRK WW
_ow
MILE
FP
PR
OJEC
TED
'RO
JECT=
1WEL
VE
D
1ILE
CRE
K SLR VI
CE
ARE
CR
OOKE
D C
REE
K DIV
ERS
ION
2000
FIGURE 6
PROJECTED
WASTEWATER FLOW
2005
2010
YEAR
2015
2020
2025

A
Figure 7
General Soils Map
,k,/ REED

s
EXISTING POTW
•
EXISTING
SIX MILE
CREEK P/
PROPOSED POTW
EXISTING PUMP STATION
PROPOSED PUMP STATION
PROPOSED FORCEMAIN
EXISTING GRAVITY SEWER
FIGURE 8
ALTERNATE 1
EXPAND EXISTING WWTP
41WKIM&CREED
NORTH
1 0 1 Miles

� o
EXISTING
SIX MILE
CREEK P/
J,
�6
EXISTING POTW
PROPOSED POTW.
EXISTING PUMP STATION
PROPOSED PUMP STATION
PROPOSED FORCEMAIN
EXISTING GRAVITY SEWER
FIGURE 9
ALTERNATE 2
LAND APPLICATION
e►NFImVIF�CR�
1
NORTH
0
1 Miles
PUMP TO LAND
APPLICATION SITE

J
0 EXISTING POTW
MI PROPOSED POTW
0 EXISTING PUMP STATION
A PROPOSED PUMP STATION
0
EXISTING
SIX MILE
CREEK P/
PROPOSED FORCEMAIN
EXISTING GRAVITY SEWER
FIGURE 10
ALTERNATE 3
PUMP TO CHARLOTTE
MECKLENBURG UTILITIES
...1 4,44amsecREED
40
NORTH
1 0 1 Miles

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Twelve Mile Creek Reliability Upgrade
rs-3s?
Subject: Twelve Mile Creek Reliability Upgrade
Date: Mon, 17 Mar 2003 13:23:26 -0500
From: "Sid Riddick" <[e-mail]>
To: "Jackie Nowell (E-mail)" <[e-mail]>
CC: "Mark Tye (E-mail)" <[e-mail]>
Jackie,
As promised, I'm providing clarification about the "reliability upgrades" planned
for the Twelve Mile Creek WWTP (Permit NC 0085359). Union Co proposes to install a
new emergencyemergancy generator_at the site to provide electrical power to the biological
treatment units, clarifiers, filters and UV disinfection systems (there is already
one for the influent pump station). In addition, there are plans to replace the
existing "hard -wired" SCADA data highway with a fiber optic cable to cut down on
lightning damage to plc's and other sensitive equipment. Finally, vfd's for the the
influent pumps, return sludge pumps and waste sludge pumps are out'of date
technology and Union Co has trouble with repair service and wishes to replace the
existing equipment with current technology. These improvements were to be
incorporated into the expansion plans. The issues associated with repermitting will
probably delay our submitting the expansion plans for an "ATC" until the fall of
2003. The new NPDES Permit which now includes limits for total phosphorous, suggest
it would be beneficial to proceed with the above listed improvements. Although the
generator would be sized for future capacity, the work described above would not
result in any change in capacity at the treatment plant. Under these circumstances,
is an "ATC" necessary.
Thanks in advance, Sid
o`r-tivi
c-pLoc3
„:ct -/b 0-- ,A._--fv.-A,4,„-4
1 of 1 3/18/03 1:45 PM

NPDES Permit/WWTP Expansion -Union Co Twelve Mile Creek
Subject: NPDES Permit/WWTP Expansion -Union Co Twelve Mile Creek
Date: Fri, 7 Mar 2003 13:57:50 -0500
From: "Sid Riddick" <[e-mail]>
To: "Jackie Nowell (E-mail)" <[e-mail]>
Jackie,
We are anxious to begin the "formal" NPDES Permit process to expand the Union Co
Twelve Mile Creek WWTP, and I have a number of questions:
1) who do we send the Engineering Alternatives Analysis (EAA) to, and how many
copies [c_ �e „s (At2) same question for the draft EA q✓C Z. x, ,P-
3) the County wants to move ahead with several "reliability improvements" (standby
AF generator, SCADA/telementry upgrades, pump VFD replacements) that do not impact
capacity. Who reviews these plans .\ •u s}tt
I'll look forward to hearing from you on these issues.
Thanks in advance
Sid Riddick
PS: I called Mike Myers number. Is he gone? yam_
AA-(11490.
/9AfjvsriLj—
Co
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12/,L-1-
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1 of 1 3/10/03 7:43 AM

LN td h.
DWQ determination of Cu and Zn effluent limits based on SC criteria
For hardness, used the default hardness of 25 mg/1 from South Carolina.
Used four years of data from 1998 through 2002, per SC requirement used
the 1 St percentile of data.
1) for Copper
SC standard/water quality criteria CMC = 3.8 ug/1 CCC = 2.9 ugll , assumes hardness
of 25 mg/1
NCDWQ used the following equation to develop Cu limit for Union Co. -
Twelve Mile Creek, using the default hardness of 25 mg/1 from South
Carolina.
Acute = CMC= e {m [ln (hardness)] + b
a a
Chronic = CCC= e (m [ln (hardness)] + b }
c
ma , ba, mc, and be are " parameters for calculation freshwater dissolved metals
criteria that are hardness dependent . Reference: Attachment 2 from the
SCDEC Water Classifications and Standards.
For Copper, the parameters are as follows:
a = 0.9422
b
a=-1.700
m
c=0.8545
b
c=-1.702
The acute copper limit was estimated to be: e (0.9422(ln 25)- 1.7 = 3.8
The chronic copper limit was estimated to be: e (0.8545(1n 25)-1.702 = 2 9

2) for Zinc
SC standard/criteria CMC = 37 ug/1 CCC = 37 ug/1, assumes hardness of 25 mg/1
NCDWQ used the following equation to develop Cu limit for Union Co. -
Twelve Mile Creek, using default hardness of 25 mg/1 from South Carolina.
Acute = CMC= e { m [In (hardness)] + b }
a a
Chronic = CCC= e (m [In (hardness)] + b )
c
ma , ba, mc, and be are " parameters for calculation freshwater dissolved metals
criteria that are hardness dependent . Reference: Attachment 2 from the
SCDEC Water Classifications and Standards.
For Zinc, the parameters are as follows:
a = 0.8473
b
a = 0.884
m
c = 0.8473
b
c = 0.884
The acute zinc limit was estimated to be: e (0.8473(ln 25)+ 0.884 = 37.0
The chronic zinc limit was estimated to be: e (0.8473(1n 25)+ 0.884 = 37.0
&IA�1.72
134.
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35".G
35", to

UNION COUNTY PUBLIC WORKKS
TWELVE MILE CREEK \MNTP NPDES NO. NC0085359
EFFLUENT METAL CONCENTRATIONS
DATE CU (mgll) ZN (mg/I)
Aug. 26, 2002
Aug. 27, 2002
Aug. 28, 2002
Aug. 29, 2002
Aug. 30, 2002
Sept.3, 2002
Sept. 4, 2002
Sept. 5, 2002
Sept. 6, 2002
Sept. 9, 2002
0.0023 0.045
0.0037 0.042
0.0051 0.045
<.002 0.042
0.006 0.048
<.002 0.031
<.002 0.026
<.002 0.025
<.002 0.033
<.002 0.053
All samples were collected via flow proportional refrigerated sampler.
Samples were collected and preserved by Public Works staff.
Pace Analytical performed analysis. Chain of Custody and QA/QC are available for inspection.

Ambient Station at Twelve Mile Creek @ Waxhaw
STATION
SAMPLING
DATE
HARDNESS
TOTAL (MG/L
AS CACO3)
C9819500
01/20/98
30
C9819500
02/18/98
20
C9819500
03/12/98
78
C9819500
04/27/98
36
C9819500
05/20/98
40
C9819500
06/15/98
50
C9819500
07/21/98
34
C9819500
08/06/98
32
C9819500
09/15/98
54
C9819500
10/13/98
42
C9819500
11/05/98
49
C9819500
12/08/98
52
C9819500
01/05/99
39
C9819500
02/04/99
36.72
C9819500
03/04/99
42
C9819500
04/06/99
69.3
C9819500
05/11/99
48
C9819500
06/28/99
43.56
C9819500
07/21/99
54
C9819500
08/19/99
84.46
C9819500
09/13/99
74.2
C9819500
10/18/99
58.58
C9819500
11/18/99
52.085
C9819500
12/14/99
36.72
C9819500
01/19/00
42.42
C9819500
02/03/00
34.68
C9819500
03/06/00
64
C9819500
04/04/00
47
C9819500
05/10/00
44
C9819500
06/22/00
78
C9819500
07/25/00
74
C9819500
08/14/00
40
C9819500
09/11/00
55
C9819500
12/12/00
79
C9819500
04/05/0140
C9819500
06/12/0161
C9819500
09/06/0138
/5 -ivc,.
��, o sc is-61/f

DWQ determination of Cu and Zn effluent limits based on SC criteria
For hardness, used the default hardness of 25 mg/1 from South Carolina.
Used four years of data from 1998 through 2002, per SC requirement used
the 1st percentile of data.
1) for Copper
SC standard/water quality criteria CMC = 3.8 ug/1
of 25 mg/1
NCDWQ used the following equation to develop Cu limit for Union Co. -
Twelve Mile Creek, using the default hardness of 25 mg/1 from South
Carolina.
Acute = CMC= e {m [In (hardness)] + b }
a a
Chronic = CCC= a {m [In (hardness)] + b }
c
CCC = 2.9 ug/1 , assumes hardness
ma , ba mc, and be are cc parameters for calculation freshwater dissolved metals
criteria that are hardness dependent . Reference: Attachment 2 from the
SCDEC Water Classifications and Standards.
For Copper, the parameters are as follows:
a = 0.9422
b
a = -1.700
m
c = 0.8545
b
c = -1.702
The acute copper limit was estimated to be: e (0.9422(ln 25)-1.7= 3.8
The chronic copper limit was estimated to be: e (0.8545(ln 25)-1.702 = 2.9

2) for Zinc
SC standard/criteria CMC = 37 ug/1 CCC = 37 ug/1 , assumes hardness of 25 mg/1
NCDWQ used the following equation to develop Cu limit for Union Co. -
Twelve Mile Creek, using default hardness of 25 mg/1 from South Carolina.
Acute = CMC= e { ma [In (hardness)] + ba }
Chronic = CCC= e {mc [In (hardness)] + b )
ma , ba mc, and be are " parameters for calculation freshwater dissolved metals
criteria that are hardness dependent . Reference: Attachment 2 from the
SCDEC Water Classifications and Standards.
For Zinc, the parameters are as follows:
a = 0.8473
b
a = 0.884
m
c = 0.8473
b
c=0.884
The acute zinc limit was estimated to be: e (0.8473(In 25)+ 0.884 = 37.0
The chronic zinc limit was estimated to be: e (0.8473(ln 25)+ 0.884 = 37.0

Union Co
4.
Subject: Union Co
Date: Thu, 16 Jan 2003 10:56:29 -0500
From: [e-mail]
Organization: NC DENR DWQ
To: "[e-mail]" <[e-mail]>,
"[e-mail]" <[e-mail]>,
Dave Goodrich <[e-mail]>
Hello Dee, per your telephone call earlier this week regarding the
change in the copper and zinc limits for Union Co. After consultation
with Dave, he recommended that we use the SC default hardness values to
calculate the limits, based on the draft letter from EPA that we
received on Dec. loth. (Although the final approval letter from EPA
made no mention of using SC hardness, we had already made the changes
and finalized the permit.) Since there is so little difference in the
proposed limits and the final limits, we just incorporated the new
limits. Attached you will find the equations used and by changing the
hardness from 23.9 mg/1 to 25 mg/1, you basically have the SC criteria
as the effluent limits for Cu and Zn in the Union Co. permit.
Copper (daily max.)
Copper (weekly avg.)
Zinc (daily max.)
Proposed
3.6 ug/1
2.75 ug/1
35.6 ug/1
Thanks and hope this clears up the matter.
Final
3.8 ug/1
2.9 ug/1
37 ug/1
D1 Union Co - revised metals limit equations.doc
Name: 1_Union Co - revised metals
limit equations.doc
Type: Microsoft Word Document
(application/msword)
Encoding: base64
Download Status: Not downloaded with message
1 of 1 1/16/03 10:57 AM

DWQ determination of Cu and Zn effluent limits based on SC criteria
For hardness, used the default hardness of 25 mg/1 from South Carolina.
Used four years of data from 1998 through 2002, per SC requirement used
the 1st percentile of data.
1) for Copper
SC standard/water quality criteria CMC = 3.8 ug/1
of 25 mg/1
NCDWQ used the following equation to develop Cu limit for Union Co. -
Twelve Mile Creek, using the default hardness of 25 mg/1 from South
Carolina.
Acute = CMC= e (in[ln (hardness)] + b }
a a
Chronic = CCC= e (m [In (hardness)] + b }
c
CCC = 2.9 ug/1 , assumes hardness
ma , a bmc, and be are " parameters for calculation freshwater dissolved metals
criteria that are hardness dependent . Reference: Attachment 2 from the
SCDEC Water Classifications and Standards.
For Copper, the parameters are as follows:
a = 0.9422
b
a = -1.700
m
c=0.8545
b
c = -1.702
The acute copper limit was estimated to be: e (0.9422(ln 25)- 1.7= 3.8
The chronic copper limit was estimated to be: e (0.8545(In 25)-1.702 = 2.9

2) for Zinc
SC standard/criteria CMC = 37 ug/1 CCC = 37 ug/1 , assumes hardness of 25 mg/1
NCDWQ used the following equation to develop Cu limit for Union Co. -
Twelve Mile Creek, using default hardness of 25 mg/1 from South Carolina.
Acute = CMC= e { ma [in (hardness)] + ba
Chronic = CCC= e {m [In (hardness)] + b }
c
ma , ba mc, and be are " parameters for calculation freshwater dissolved metals
criteria that are hardness dependent . Reference: Attachment 2 from the
SCDEC Water Classifications and Standards.
For Zinc, the parameters are as follows:
a = 0.8473
b
a=0.884
m
c = 0.8473
b
c=0.884
The acute zinc limit was estimated to be: e (0.8473(ln 25)+ 0.884 = 37.0
The chronic zinc limit was estimated to be: e (0.8473(ln 25)+ 0.884 = 37.0

UNION COUNTY PUBLIC WORKS DEPARTMENT
Jon C. Dyer, P.E., Director
January 14, 2003
Ms. Jacquelyn Nowell
NCDENR
Division of Water Quality
1617 Mail Service Center
Raleigh, North Carolina 27699-1617
SUBJECT: NPDES Permit No. NC0085359
Twelve Mile Creek WWTP
Union County
Dear Ms. Nowell:
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Public Works is in receipt of the referenced permit dated December 13, 2002.
Section A. (1.) of the Permit sets forth effluent limitations and monitoring
requirements. Among the effluent limitations are daily maximum metal
concentration for copper and zinc of 3.8 ug/I and 37.0 ug/I respectively.
Based on past effluent metal analysis, and under current operating procedures,
UCPW will not be able to meet the metal concentrations contained in the Permit
on a regular basis. UCPW understands that a twenty-one (21) month schedule
of compliance has been granted; at the end of which, UCPW must either 1) have
developed site -specific standards or 2) be capable of achieving limits for copper
and zinc contained in the Permit.
UCPW is contracting with the engineering firm Hazen & Sawyer to provide
technical assistance in the development of site -specific standards. The study and
report will be completed well within the twenty-one (21) month window.
Hazen & Sawyer has experience in developing site -specific standards in
accordance with "Interim Guidance on Determination and Use of Water -Effect
Ratios for Metals" EPA-823-B-94-001, February 1994.
400 North Church St. . Monroe, North Carolina 28112-4804 . Phone: [phone] . Fax: [phone]

a
UCPW is finalizing the design phase of a project that will increase the rated
capacity of the Twelve Mile Creek WWTP from 2.5 MGD to 6.0 MGD. UCPW
anticipates bidding the project in the spring/summer of 2003. With this expansion
in mind, UCPW has directed Hazen & Sawyer to develop the site -specific
standards based on an average daily flow of 6.0 MGD. Upon development of the
standards, treatment process altematives will be evaluated and implemented as
necessary to comply with final effluent limits.
Should you wish to discuss these matters in more detail, please do not hesitate
to contact Mr. Mark Tye at [phone].
Respectfully,
on C. Dyer, .E.
Public Works Director