NC0024228_Report_20000218

NPDES DOCUMENT SCANNING COVER SHEET
NPDES Permit:
NC0024228
High Point Westside WWTP
Document Type:
Permit Issuance
Wasteload Allocation
Authorization to Construct (AtC)
Permit Modification
Complete File - Historical
Engineering Alternatives (EAA)
, ,gam..:
Instream Assessment (67b)
Speculative Limits
Environmental Assessment (EA)
Document Date:
February 18, 2000
This document is printed on reuse paper - ignore any
content on the reverse side

CITY OF HIGH POINT
NORTH CAROLINA
February 18, 2000
Kerr T. Stevens
NCDENR
PO Box 29535
Raleigh, NC 27626-0535
Subject: Operation and Maintenance Assessment
To Identify Methods of Optimizing Phosphorus
Removal with Existing System.
Dear Mr. Stevens:
Enclosed ple se find two letters. One is a letter from Tim Fitzgerald and the other is a copy of
DMP Project E2031. These letters explain our requirements to meet the one year phosphorus
assessment as required in our NPDES Permit #NC0024228.
If you need any additional information, please let me know.
Sincerely,
l Tom Gore
Plants Manager
NAYS
FEB 2 1 2000
VVK I tR QUALITY
SECTION
S'1p
DIV OPO/ o4TER QaA�
S oFF�C� r.
\Or
Ck)
U PUBLIC SERVICES DEPARTMENT. P.O. Box 230, 211 S. HAMILTON STREET. HIGII POINT, NORTH CAROLINA 27261 TELEPHONE [phone] FAX [phone](19 TDD 336-883-8517

CITY OF HIGH POINT
NORTH CAROLINA
To: Tom Gore, Public Services Plants Manager
From: Timothy H. Fitzgerald, Westside Plant Supervisor
Date: 2/07/00
Subject: Phosphorus Removal Using Alum
Tx; BP, J6-
FEB 1 0 2000
Davis, Martin & Powell Engineers completed a proposal for a Phosphorus Removal System in
July of 1997.
On October 1997 general contractors Laughlin -Sutton Construction Company was granted the
contract for installation and construction of a phosphorus removal system using alum.
The project was begun in November of 1997 and was completed in April 1998. After the final
inspection and necessary corrections were made the system was placed in service in May of 1998.
The system uses a series of three alum feed pumps supplied with alum from two 13,000 gallon
fiberglass wrapped tanks. The full volume of these tanks is not utilized due to level indicating
probes and overflow lines. The average volume stored in each tank never exceeds 8,000 gallons.
Alum can be pumped to either the effluent end of the aeration basin and discharged into the
diversion box before the Final Clarifiers, or it can be pumped to the Raw Influent line ahead of
the Primary Clarifiers. Presently alum is pumped to the effluent end of the aeration basin and
discharged into the diversion box ahead of the Final Clarifiers. This site has produced the
optimum phosphorus removal of the two sites.
The system functions in both manual mode with pump run status and speed selected by the
operator (either locally or remotely), and automatic mode which adjusts pump speeds in response
to the influent flow rate, and preset dosage calculations. In automatic mode, the system alerts the
operator if the required feed rate cannot be obtained.
The bulk tanks are monitored through a PLC and provide high and low-level alarms. The pumps
themselves are also controlled by the PLC, which start and stop pumps and vary flow rates in
response to changes in plant influent flow rates.
All pumps and controls are housed in a precast concrete building. In this building a heating and
automatic louver system was installed for temperature control.
With this system Westside has consistently met the permit limit for Phosphorus.
In the future, Westside will probably be upgraded to BPR. In fact, preliminary design work has
been started.
THF: ms
PUBLIC SERVICES DEPARTMENT, PO Box 230, High Point. North Carolina, 27261
Telephone [phone] FAX [phone] TDD [phone]

CITY OF HIGH POINT
NORTI-I CAROLINA
Memo
To: Tom Gore, Public Services Plants Manager
From: Tim Fitzgerald, Westside Plant Supervisor
Date: 2/07/00
Subject: Operation and Maintenance Assessment to Identify Methods of Optimizing
Phosphorus Removal with Existing Facilities
On February 3"d I received a reply from the State on the question of performing an
operation and maintenance assessment for optimization of phosphorus removal.
According to the State we can satisfy this requirement by chronologically listing the
construction and implementation of the alum feed system for phosphorus removal and
include any studies we have done for future Plant optimization of phosphorus removal.
The State was apparently unaware of our implementation of alum for phosphorus removal
before the new permit was issued. However, it is necessary that we report the present
method being used and include any studies planned or completed by outside engineering
firms to optimize nutrient removal.
If this manner of addressing the requirement is satisfactory with you let me know and I
will submit the necessary times, dates and system operation overview as requested for
your approval and submission to the State.
1.
FEB 1 0 2000
CI;;'
P,:R1.1(' Si.izvicrs DEPAR ,\I. I n-N I . PO Box 230. I-Iigh Point, North Carolina, 27261
"Telephone [phone] FAX [phone] TDD [phone]

January, 1998
DMP PROJECT E-2031
Prepared By:
DAVIS-MARTIN-POWELL & ASSOCIATES, INC.
ENGINEERING • LAND PLANNING • SURVEYING
218 Gatewood Avenue, Suite 102
High Point, NC 27262
Phone: [phone] / Fax: [phone]/ e-mail: [e-mail]

TABLE OF CONTENTS
Executive Summary 1
1.0 ,..Introduction 4
2.0 Population and Flow Projections 5
3.0 Existing Facility 8
4.0 Evaluation of Alternatives: for Plant Expansion and Upgrade 21
4.1 General 21
4.2 Interim Needs 21
4.3 Expanded Facilities 29

INTRODUCTION
The Westside Wastewater Treatment Plant (WWTP) provides wastewater services to the western areas
of the City of High Point. The purpose of this plant evaluation is to review facilities that would be required
to increase the Westside Plant capacity from 6.2 to 9.3 million gallons per day (MGD). This increase in
capacity is required to accommodate continued growth in the service area and to comply with State regulations
limiting the discharge of nitrogen and phosphorus to Rich Fork Creek.
POPULATION AND FLOW PROJECTIONS
Population projections and wastewater flows were reviewed for the existing service area of the Westside
Plant. Projections of future population for the existing service areas were based on current populations from
the 1990 census data and county projections of population growth for Guilford County over the 20 year
planning period.
For the projections based on the Guilford County population increases, the Westside WWTP would have
reached its current permitted capacity of 6.2 MGD in 1995 and will reach a maximum month expanded flow
of 9.3 MGD about 2023. For the projections based on the historical trend analysis, the current permitted flow
of 6.2 MGD will be reached in 1997, and a maximum month flow of 9.3 MGD will be reached around 2016.
EXISTING PLANT PROCESSES
The Westside WWTP provides tertiary treatment for a permitted flow of 6.2 MGD. Major treatment
process units include screening and grit removal facilities, primary clarifiers, secondary treatment, mono media
filters for tertiary treatment, and chlorination facilities for effluent disinfection. Solids treatment facilities
consist of dissolved air flotation (DAF) thickeners for thickening of secondary solids, solids blending tank for
primary and thickened secondary solids, and a high solids centrifuge for dewatering. Solids stabilization will
be by incineration at the Eastside Plant, which is under construction. Interim solids stabilization is by anaerobic
digestion, followed by storage in a solids lagoon and land application by contract to permitted private farm
land.
EXISTING & PROPOSED NPDES LIMITS
The Westside Plant has consistently met effluent limits for BOD5, TSS, and NH3-N. Effluent limits
for metals over most of the two year period were met, except for cyanide. Cyanide testing procedures are
currently being evaluated in a study conducted by the Water Resources Research Institute for the North
Carolina Urban Water Consortium.
City of High Point - Westside WWTP Evaluation
-1-

Design influent wastewater characteristics were based on an evaluation of plant data for the two year
period from July 1994 to June 1996. Influent data for phosphorus and nitrogen is based on two months data.
More data should be collected prior to final design. A maximum month to annual average flow ratio of 1.25
was determined based on the two year period of record. A peak to maximum month average flow ratio of 2.5
was used for hydraulic evaluations of the expanded facilities. The treatment process will be fully maintained
at the corresponding peak flow of 23.3 MGD (2.5 x 9.3 MGD).
The current NPDES permit is scheduled for reissuance in October, 1998. Previous negotiation with
DWQ has resulted in the following schedule of new limits:
October 1, 1998
October 1, 2003
upon capacity expansion
2.0 mg/L total phosphorus
4.0 mg/L total nitrogen (summer)
8.0 mg/L total nitrogen (winter)
0.5 mg/L total phosphorus
The City also desires to construct ultraviolet disinfection facilities prior to the 1998 permit cycle. These
facilities will serve to eliminate the on -site storage of chlorine gas and also reduce effluent toxicity associated
with chlorine and chlorine byproducts.
EVALUATION OF FACILITIES FOR PLANT EXPANSION AND UPGRADE
Facilities for expansion and upgrade of the Westside WWTP were evaluated based on ability to meet
projected nutrient removal requirements; ability to meet more stringent effluent limits for conventional
pollutants; hydraulic considerations, site conditions and constraints, operability, flexibility, reliability, and input
from City Staff.
Proposed modifications to the preliminary treatment facilities include installing a second bar screen in
the existing bypass channel and installing a larger parshall flume and associated instrumentation. The existing
aerated grit chambers will be adequate for the increased flow, although the removal efficiency may be reduced.
The existing primary clarifier capacity should be increased for the expanded plant flow by the addition
of a new primary clarifier the same size as the existing clarifiers. The proposed primary clarifier would operate
in parallel with the existing primary clarifiers. The proposed facilities would include a new distribution box,
the addition of grinders, and replacement of the existing primary solids pumps in the existing pump station;
The driving force behind future upgrades is the need for compliance with the proposed nitrogen and
phosphorus limits. The chemical phosphorus removal facility under construction will allow the facility to meet
the 1998 request of 2.0 mg/L total phosphorus.
Evaluation of the existing facilities indicated that the WWTP would be unable to meet the proposed
2003 nitrogen limits without major modifications. Based on the projected wastewater flow patterns, it is most
City of High Point - Westside WWTP Evaluation
2

economical to combine the necessary BNR upgrade with a modest capacity expansion, timed to meet the 2003
permit cycle.
The proposed facilities would be a five stage process, generally known as a modified UNC process.
The new facilities would include modification of existing aeration basins, the addition of anoxic/aeration basins,
a recycle pump station, a fermentation tank, and a secondary clarifier. These new facilities and the continued
use of the existing facilities will provide greater operating flexibility in the treatment process.
Expansion of .the effluent filters will be necessary to provide an increased capacity. The existing filters
are not operating efficiently and should be upgraded as an interim improvement. Construction of additional
filters similar to the existing filters is recommended for the expanded plant.
Ultraviolet disinfection is being added at the present time in 1998 and is expandable to 9.3 MGD with
the addition of more UV modules.
With an increase in the plant flows, an increase in solids productions can be expected. In order to
accommodate these increases, it is recommended that the solids treatment facilities be upgraded. A second
dissolved air flotation (DAF) thickener should be installed in the existing chlorine contact basin. The remaining
anaerobic digester should be converted to a solids blending tank. This will provide for a more uniform sludge
supply for the recently installed centrifuge. Also, as flows increase, additional operating time of the centrifuge
will be required. A second centrifuge should be installed for backup and alternating use.
The current NPDES permit does not require a standby power system. It is anticipated that a secondary
power source will be required during a future permitting cycle or earlier if other improvements result in permit
modifications. It is recommended that a diesel driven generating unit be installed to prevent discharge of
inadequately treated wastewater during primary power outages.
RECOMMENDED FACIUTIES.AND ESTIMATED COSTS •
Recommended facilities for the proposed expansion of the Westside WWTP are shown in Figure WS-1.
A list of recommended facilities and associated cost estimates are provided in Table 4.6 and summarized below.
WESTSIDE WASTEWATER TREATMENT PLANT •
PROJECT COST SUMMARY
Project
Table
Construction
oject
Interim Phosphorus Removal
4.1
$234,200
$273,400
Interim Ultraviolet Disinfection
4.4
$1,050,000
$1,220,000
Interim Filter Improvements
$250,000
$300,000
Plant Expansion
4.8
$10,750,000
$12,900,000
Standby Power System
4.6
$750,000
$900,000
City of High Point - Westside WWTP Evaluation
3

BACKGROUND
The City of High Point is located in the northern Piedmont of North Carolina and in southwestern
Guilford County. The wastewater service area includes the City of High Point, the City of Archdale, the Town
of Jamestown, and the Sedgefield Sanitary District, as well as surrounding areas adjacent to the High Point
corporate limits.
The existing High Point sewer system includes approximately 500 miles of sewers, 28 wastewater
pumping stations, and two wastewater treatment plants. A major ridge line divides the City into two distinct
watersheds: the Cape Fear River Basin to the east and the Yadkin River Basin to the west. Gravity sewers to
the east and west of the ridge line flow to the Eastside and Westside Wastewater Treatment Plants, respectively.
The Eastside Plant provides service to northern, eastern, and southern areas within and surrounding the City.
The Westside Plant provides service to western areas only. The Eastside Plant also receives flows from
Archdale, Jamestown, and the Sedgefield Sanitary District.
PURPOSE AND SCOPE
The purpose of this preliminary Engineering Report is to review facilities required to upgrade the
Westside WWTP to meet immediate and interim needs as well as to address facilities required to meet
projected needs for a twenty-year planning period. Westside's immediate needs include a remedy for the
flooding problem during heavy rains. The interim goals include meeting a reduced phosphorus limit of 2.0
mg/L by October, 1998 and the implementation of ultraviolet disinfection. Future goals include meeting a
reduced nitrogen limit in 2003, and a facility expansion.
Population and flow projections are presented and were used to determine design wastewater flows over
the planning period. Projected influent wastewater characteristics based on an analysis of existing plant
operating records are also presented. Evaluations of alternatives to meet treatment needs for an expanded plant
from the current 6.2 MGD permitted capacity to 9.3 MGD are discussed. An analysis of plant hydraulics are
also included. Recommended facilities for the plant upgrade and expansion • are discussed along with cost
estimates.
City of High Point - Westside WWTP Evaluation - 4 -

DEMOGRAPHICS
High Point is an industrial and distribution center of the Piedmont of North Carolina. It is located along
several major highways including Interstate 40 to the north, Interstate 85 to the south, U.S. Highway 311, and
N.C. Highway 68. It is also served by a main line of the Southern Railway and by the Piedmont Triad
International Airport.
Major industries in High Point include furniture and textile manufacturing. The principal industrial
sources of wastewater are derived from textile and furniture manufacturers, textile chemicals, coatings
manufacturers, electroplaters, steel drum cleaners, and dairies.
The City of High Point has recently annexed an area in the north along the Highway 68 Corridor. This
annexation extends the City service area to Gallimore Dairy Road and Guilford College Road. This area is
designated for mixed use, including significant office and institutional development. Most of the remainder
of the Highway 68 Corridor is designated for residential or agricultural uses, with an associated very low
residential density to protect the watersheds of Oak Hollow and City Lakes, both of which are primary water
supply reservoirs for the City of High Point.
High Point owns the electrical power, distribution, and transmission lines within the City limits and sells
electricity to its customers after purchasing power on a wholesale basis from Electricities Consortium.
Telephone services are provided by North State Telephone Company, natural gas by Piedmont Natural Gas,
and cable television by Cablevision of High Point and Alert Cable TV.
The City of High Point Water Treatment Plant is rated at 16 MGD. Construction is underway to
expand its capacity to 32 MGD. Raw water is currently supplied from either City Lake or Oak Hollow Lake.
Additionally, the City has a contract with the Piedmont Triad Regional Water Authority for future purchase
of up to 10 MGD of water from Randleman Lake.
Land use inside the corporate limits of High Point and the extraterritorial limits outside the City is
regulated by the High Point Department of Planning and Community Development. Outside of these
boundaries, the primary growth areas are regulated by the adjacent municipalities or counties. Land use is
divided into five main categories: residential, office/institutional, commercial, industrial, and public open space.
Population projections for the City of High Point service area provide the basis for planning of
necessary wastewater treatment facilities improvements to accommodate the associated wastewater system's
flows. Population projections were prepared through the year 2015 for both existing and future service areas.
Future service areas include areas where major collection outfalls have been, or are being, considered to provide
service to growing areas.
City of Nigh Point - Westslde WWTP Evaluation 5

POPULATION PROJECTIONS FOR EXISTING SERVICE AREAS
The U.S. Census Bureau estimated the 1992 population for the City of High Point at 69,424. Census
population projections for Guilford County were used to project future populations for the City of High Point.
TABLE 2.1
Guilford County .
ountywide Population
6 Increase
Projected Hlgh Point.''
Population
1995
364,252
---
71,160
2000
375,107
3.0
73,295
2005
382,908
2.1
74,835
2010
391,817
2.1
76,405
2015
410,485
4.9
80,150
FLOW PROJECTIONS FOR EXISTING SERVICE AREA
An analysis of historical flow records for the Westside Plant for the past 12 month period from July,
1995 through June, 1996 results in a total average daily flow (ADF) of 5.3 MGD for the Westside Wastewater
Treatment Plant.
TABLE 2.2
Existing Service -Area
Projected ADF (MGD)
95-96
5.3
2000
5.5
2005
5.6
2010
5.7
2015
6.0
The projected wastewater flows to the Westside Plant from the City of High Point were estimated based
on the current flow rate from July, 1995 through June, 1996 and the projected increases in population to the
year 2015. It is assumed that the per capita wastewater flow rate will not change over the 20 year planning
period. The per capita wastewater flow rate includes residential, commercial, industrial, and infiltration/inflow
(I/I) flows. It is assumed that nonresidential wastewater flows will increase at the rate as residential flows.
FLOW PROJECTIONS FOR FUTURE SERVICE AREAS
The future service areas that will contribute flows to the Westside Plant consist of two major drainage
subbasins. The subbasins include existing or potential collection outfalls and each subbasin is expected to
continue to develop within the planning period.
City of Hlgh Point - Westside WWTP Evaluation 6

Estimated flows in the subbasins include residential, commercial, industrial, and I/I flows and are based
upon equivalent populations. The equivalent population projections were developed in a previous study for the
City of High Point by Hazen and Sawyer during 1988. The projected densities of development for the 20 year
planning period are as follows:
Land Use
TABLE 2.3
Equivalent Persons/Acre
Residential 2.0
Office & Light Industrial 8.0
Heavy Industrial 13.0
For each subbasin, current zoning and projected land use patterns were used to determine the projected
population equivalents. An average wastewater contribution of 100 GPD was applied to the projected
population equivalents. Flow projections for the Westside Wastewater Treatment Plant growth areas are as
follows:
ear
TABLE 2.4
Westside Subbasin. Growth Areas (MGD)
WWTP Subbasins
Abbotts Creek Area (No Outfalls)
2000
0.2
0.0
2005
0.4
0.0
2010
0.6
0.0
2015
0.8
0.0
COMBINED WASTEWATER FLOW PROJECTIONS
To project future wastewater flows for the Westside Wastewater Treatment Plant, existing and future
service area flow projections were combined as follows:
TABLE 2.5
Westside Flow Projections (MGD}:'.;
Within Ci
Subbasins Projected ADF Projected Peak Month (ADF) •
1996
5.3
0.0
5.3*
6.6*
2000
5.5
0.2
5.7
7.1
2005
5.6
0.4
6.0
7.5
2010
5.7
0.6
6.3
7.9
2015
6.0
0.8
6.8 •
8.5
* Based on Westside Plant flow data for 7/95 - 6/96.
The projected peak month flows are based on a ratio of the highest recorded monthly flow during the
past year divided by the average daily flow (ADF) for the same year. A peak month flow factor of 1.25 times
the ADF was used. It is recommended that a facility expansion to 9.3 MGD be incorporated into the design
of facilities to meet the 2003 nitrogen limits.
City of High Point - Westside WWTP Evaluation
7

_o
0
2
16.0
14.0
12.0
10.0
8.0
6.0
4.0
2.0
1996
—ADF
--— Peak Month
---f— High Historical
—0— Mid Historical
--�— Low Historical
Current
Expanded
2001
Figure 2.1
Projected Flows
2006
f Year
2011

GENERAL
The Westside Plant was originally constructed incorporating an activated sludge process during the
1920's. Various expansions and upgrades were conducted throughout the years and the plant was upgraded to
an average daily flow of 6.2 MGD with a corresponding peak hydraulic capacity of 12.4 MGD during the early
1980's. Flow is transported to the plant site by three outfalls: the Rich Fork Creek Outfall, the Kool Pool
Outfall, and the Ensley Creek Outfall.
Influent screw pumps lift flow to the plant treatment facilities. From the pump discharge, flow is routed
by gravity through influent bar screens, two aerated grit chambers, a parshall flume, and two primary clarifiers.
Primary effluent is then mixed with return activated sludge and a portion of the combined flow is pumped to
a biofilter which discharges to downstream aeration basins. The remainder of the combined flow directly
discharges to the aeration basins by gravity. Three aeration basins and two secondary clarifiers are provided.
Effluent from the secondary clarifiers flows by gravity through tertiary filters and chlorine contact basins.
Plant effluent is discharged through a 36 inch outfall to Rich Fork Creek.
INFLUENT WASTEWATER CHARACTERISTICS AND LOADINGS
Wastewater characteristics of significance in the design of wastewater treatment facilities include
oxygen -demanding materials and materials that can settle out in receiving streams, including BOD, ammonia
nitrogen, and suspended solids. Other parameters of concern include toxic substances, heavy metals, and
cyanide which can have an impact on the biological processes and affect disposal of the residual solids. The
presence of large solids, such as sticks and rags; heavy inorganics, such as sand and grit; and floatable
materials, such as grease and scum, must also be considered in the design of wastewater treatment facilities.
Influent data for the Westside Plant for the two-year period from July, 1994 through June, 1996 were
reviewed to develop projected wastewater characteristics. Projected wastewater characteristics are summarized
in Table 3-1. Design annual average BODS and TSS concentrations are based on plant record data. As there
is not any historical data on influent nitrogen and phosphorus available, the values are based on the past two
months data. Collection of additional plant influent, nitrogen, and phosphorus data is recommended prior to
final design.
For the purpose of the hydraulic evaluations conducted for this study, a peak hourly flow ratio of 3.0
is assumed for containing flow within tanks. At a peak daily flow ratio of 2.5, weirs will be unsubmerged on
all tanks, thereby providing full process capability at a peak flow of 2.5 times the average flow. Design of
City of High Point - Westside WWTP Evaluation
8

facilities for these peak flows will minimize the potential for wastewater overflows from the treatment plant
and collection system.
TABLE 3.1
DESIGN INFLUENT WASTEWATER CHARACTERISTICS
6.2 MGD 9.3 MGD
Parameter - Maximum Month Conditions Units Existing Capacity Expanded Capacity
Design Flow MGD 6.2 9.3
BOD5 mg/L 185 185
lb/day 9570 14354
Total Suspended Solids mg/L 330 330
lb/day 17070 25606
Total Kjeldahl Nitrogen, as N mg/L 12 12
lb/day 621 931
Ammonia Nitrogen, as N mg/L 9.9 9.9
lb/day 512 768
Total Phosphorus, as P mg/L 8.5 8.5
lb/day 440 660
Note: Design instantaneous peak flows are 3.0 times maximum month flows.
HISTORICAL PLANT PERFORMANCE
Performance data showing monthly influent and effluent characteristics for the two-year period from
July, 1994 through June, 1996 and effluent characteristics for heavy metals, cyanide and chronic toxicity for
the same period is summarized in Tables 3.2 and 3.3, respectively. For 1995-96, influent flow to the Westside
Plant averaged 5.3 MGD.
Table 3.2 shows influent and effluent BOD5, total suspended solids (TSS), ammonia nitrogen (NH3 N),
and total phosphorus (P) concentrations. The NPDES permit includes effluent limits for all of these parameters
except phosphorus, for which a limit of 2.0 mg/L is proposed in October, 1998, and a limit of 0.5 mg/1 upon
plant expansion. The plant consistently met permit limits for these parameters over the two-year period.
The NPDES permit for Westside also specifies effluent limits for dissolved oxygen, fecal coliforms,
and pH. The effluent dissolved oxygen limit was exceed on one occasion in January, 1996 and the weekly
average fecal coliform limit was exceeded two times in 1995 and 1996.
Effluent limits for heavy metals and cyanide are also included in the current NPDES permit. Over the
two-year period evaluated, the plant met permit limits for these parameters except for cyanide, chromium, and
City of High Point - Westside WWTP Evaluation
9

nickel. The effluent limit for nickel was exceeded in June and July of 1995. The effluent limit for cyanide
was exceeded for nearly all the months over the two-year period.
TABLE 3.2
INFLUENT AND EFFLUENT WASTEWATER CHARACTERISTICS
Influent
Effluent
Month Flow
,.:
BOD5 TSS NH3-N
mg/I mg/I .. mg/I
BODS TSS NH3-N P
mg/1 mg/I mg/I mg/I
July 1994
4.64
198
286
21.0
3.7
3.95
0.34
_
2.66
August 1994
4.72
175
257
22.6
3.8
3.00
0.70
September 1994
4.60
172
297
30.0
4.5
2.76
0.40
8.82
October 1994
4.11
180
357
30.0
6.8
2.43
0.40
5.68
November 1994
4.19
172
324
23.0
5.1
3.15
0.41
2.80
December 1994
4.08
186
307
36.0
5.0
3.19
0.13
1.95
January 1995
5.01
187
302
30.2
4.1
3.45
0.14
1.45
February 1995
5.68
177
281
24.9
5.8
6.00
0.18
5.23
March 1995
5.83
170
299
'
26.2
5.6
2.91
0.67
2.65
April 1995
4.30
183
287
29.1
5.0
6.68
0.03
3.32
May 1995
3.60
172
350
28.4
5.4
7.00
0.05
3.67
June 1995
4.61
161
412
24.3
4.0
6.05
0.04
2.07
July 1995
4.45
161
283
18.1
4.0
4.45
1.13
6.24
August 1995
4.55
172
333
18.0
4.0
3.87
0.07
7.04
September 1995
4.51
167
329
23.6
4.0
4.05
0.05
4.68
October 1995
5.52
169
392
18.5
4.0
6.68
0.08
4.06
November 1995
5.78
134
340
'
21.0
4.0
8.58
0.02
6.08
December 1995
5.28
`
200
344
18.8
3.0
4.79
0.13
2.23
January 1996
6.45
202
351
14.9
7.0
7.62
0.47
2.08
February 1996
6.12
242
384
23.0
9.0
9.67
0.22
0.70
March 1996
6.03
235
317
23.5
6.0
4.81
0.11
4.39
April 1996
5.55
185
356
15.7
5.0
' 5.67
0.06
3.19
May 1996
4.60
197
326
-
19.1
6.0
4.77
0.21
4.47
June 1996
4.22
202
314
21.4
6.0
4.80
0.16
7.18
Average BOD5 Removal: 97.3% Average TSS Removal: 98.5% Average NH3-N Removal: 98.9%
City of Nigh Point - Westside WWTP Evaluation
- 10-

TABLE 3.3
EFFLUENT CHARACTERISTICS FOR METALS AND CHRONIC TOXICITY
Cyanide
Chronic •
Toxlclty`
July 1994
<1.0
9.5
67
<5.0
<5.0
Pass
August 1994
<1.0
<5.0
<50
<5.0
<5.0
September 1994
<1.0
7.35
<50
<5.0
24.0
October 1994
<1.0
5.6
55
<5.0
7.0
Pass
November 1994
<1.0
<5.0
<50
<5.0
20.0
December 1994
<1.0
<5.0
<50
7.63
5.5
January 1995
1.0
<5.0
<50
5.0
8.0
Pass
February 1995
<1.0
<5.0
<50
5.48
54.0
March 1995
1.49
10.79
<50
<5.0
37.0
April 1995
<1.0
5.58
<50
<5.0
45.0
Pass
May 1995
<1.0
5.94
<50
<5.0
10.0
June 1995
<1.0
11.62
610
5.59
<5.0
July 1995
<1.0
387
145
<5.0
159
Pass
August 1995
<1.0
8.59
79.0
5.25
8.0
September 1995
<1.0
<5.0
<10.0
10.82
<5.0
October 1995
<1.0
8.82
<10.0
5.13
<5.0
Pass
November 1995
<1.0
11.95
<10.0
5.46
<5.0
December 1995
<1.0
10.13
27.9
<5.0
<5.0
January 1996
<1.0
9.15
51.19
<5.0
<5.0
Fail
February 1996
<1.0
8.67
12.1
6.75
7.0
Fail
March 1996
<1.0
5.82
12.8
<5.0
<5.0
Fail
April 1996
<1.0
14.52
42.5
<5.0
6.0
Fail
May 1996
<1.0
6.93
42.1
5.45
5.0
Pass
June 1996
<1.0
5.56
17.0
7.24
<5.0
* Maximum concentration in a given month, ug/L.
The effluent limit for chromium was exceeded one time in July, 1995.
City of Nigh Point - Westside WWTP Evaluation
- 11 -

REGULATORY AGENCY REQUIREMENTS
The Westside Wastewater Treatment Plant is operated under NPDES Discharge Permit No. NC0024228
which became effective on December 1, 1993 and will expire on September 30, 1998. This permit sets effluent
limits for the existing permitted flow of 6.2 MGD. The existing effluent limits are as follows:
TABLE 3.4
Flow, MGD
6.2
BOD5, mg/1 5
Total Suspended Solids, mg/L 30
Ammonia Nitrogen, mg/L 2
Fecal Coliforms, No./100 mL 200
Dissolved Oxygen, mg/L 6
pH 6-9
Chromium, ,ug/L 53
Nickel, ,ug/L 94
Cadmium, ,ug/L 2
Lead, ,ug/L 27
Cyanide, ,ug/L 5
Mercury, ,ug/L 0.013
6.2
10
30
4
200
6
6-9
53
94
2
27
5
0.013
All permit concentration limits are monthly averages except for heavy metals and cyanide which are
daily maximums. The existing permit also requires effluent monitoring for total residual chlorine, temperature,
total nitrogen, total phosphorus, chronic toxicity, and priority pollutants.
Solids disposal for the Westside Plant is by land application of liquid anaerobically digested sludge to
permitted privately owned farmland. Solids hauling and land application is by contract to AMSCO in
Clemmons, N.C. The land application program is operated under Permit No. WQ0001897, issued on March
31, 1995 and expiring on February 28, 1997. Currently, 3,295 acres are permitted for land application of both
Westside and Eastside solids. Facilities for incineration of dewatered sludge are under construction at the
Eastside WWTP with completion anticipated in Spring, 1998.
O&M ISSUES
A workshop was held for all City employees who are involved with the overall management, the daily
operation, and maintenance of the Westside Plant. Problems and concerns with the existing facilities were
discussed as well as considerations to be reviewed during plant expansion design process. A brief summary
of issues raised follows:
• The effluent filters seem to be the biggest trouble spot in the plant. The filters have
been very inefficient in the past, although recent repairs seem to have helped the
City of High Point - Westside WWTP Evaluation
- 12-

situation. Possible upgrades, as well as alternate filtration methods, should be
investigated.
• The existing grit removal system works fine. and is in good mechanical condition. But
a problem arises during the shut -down start-up process. When the grit removal buckets
are stopped, grit builds up on the chain and bucket. The built up grit must then be
removed manually before restarting the buckets. A possible solution to this problem
should be researched.
• The influent screw pumps have had problems with drives and bearings. The lower
drives and bearings may need replacing.
• Installation of a second centrifuge should be considered for plant expansion.
• Because of recent flooding, electrical equipment should be moved upstairs where
practical, and future facilities should be designed accordingly.
EXISTING FACILITIES DESIGN DATA
Design data for the existing facilities at the Westside Plant, including the recent solids handling facility
upgrade, is included in the following table. This information has been compiled from existing plans,
specifications, and O&M manuals.
City of High Point - Westside WWTP Evaluation - 13 -

TABLE 3.5
EXISTING FACILITIES
DESIGN DATA
Influent Pumping Station
Archemedian Screw Pump
Number 3
Diameter, inches 72
Capacity, each, GPM 8611
Lift, feet 26.2
Motor horsepower, each 100
Bar Screen
Mechanically Cleaned Screen
Number 1
Capacity, MGD 12.5
Clear screen opening, inches 1/2
Screen width, feet 4
Motor horsepower 2
Grit Removal
Aerated Grit Chambers
Number 2
Dimensions
Length, feet 38
Width, feet 7
Sidewall Water Depth, feet 9.75
Volume, each, gal. 19400
Total Volume, gal. 38800
Design Flow, each, MGD 6.2
Detention time, one unit © 6.2 MGD, min. 4.5
Flow Measurement
Type Parshall flume
Number 1
Range, MGD 0.3 - 21.4
Throat Width, inches 24
Primary Clarifiers
Type Circular, Center Feed
Number 2
Diameter, feet 70
Sidewall Water Depth, feet 12
Surface Area, each, ft2 3850
Total Surface Area, ft2 7700
Overflow Rate © Design Flow of 6.2 MGD, GPD/SF 805
Detention Time © 6.2 MGD, hr. 2.7
Sludge Pumps
Number 2
Capacity, each, GPM 15 - 45
Motor Horsepower 5
City of High Point - Westside WWTP Evaluation
- 14 -

TABLE 3.5 - EXISTING FACILITIES, DESIGN DATA (Continued)
Scum Pumps
Number 1
Capacity, each, GPM 45 - 210
Motor Horsepower 20
Biological Filter
Synthetic Media
Number 1
Diameter, feet 70
Media Depth, feet 20
Total Area, ft2 3850
Total Volume, ft3 77000
Distribution System Rotating Distributor
Minimum Wetting Rate, GPD/SF 0.8
Recirculation Pumps
Wet Pit, Vertical Turbine, Two Speed
Number 3
Capacity, Design - 3 pumps, GPM, Total 10750
Motor Horsepower, each 50
Aeration Basins
Number 3
Length, feet 297
Width, feet 23
S idewal l Water Depth, feet 15
Volume, each, mil. gal. 0.77
Total Volume, mil. gal. 2.29
Detention Time at Plant Design Flow of 6.2 MGD, hrs. 8.9
Aeration System
Fixed, Fine Bubble, Diffuser
Type of Diffuser 9 inch ceramic disk
Number of Diffusers per Basin 1300
Total Number of Diffusers 3900
Air Flow, Rated Capacity 1.5 SCFM/Diffuser
Blowers
Multistage Centrifugal
Number • " 3
Capacity
One Unit, SCFM 2100
Two Units, SCFM 3000
Three Units, SCFM 5680
Motor Horsepower, each 100
Final Clarifiers
Circular, Center Feed, Sludge Suction Withdrawal
City of High Point - Westside WWTP Evaluation
- 15 -

TABLE 3.5 - EXISTING FACILITIES, DESIGN DATA (Continued)
Number 2
Diameter, feet 90
Sidewall Water Depth, feet 14
Surface Area, each, ft2 6360
Total Surface Area, ft2 12720
Overflow Rate at Design Flow of 6.2 MGD, GPD/SF 487
Detention Time at Design Flow of 6.2 MGD, hr. 5.2
Recycle Pumping Station
Centrifugal, Variable Speed
Number 3
Capacity, any two units, GPM 4350
Motor Horsepower 15
Effluent Filters
Gravity, Continuous Backwash
Number 2
Dimensions
Length, feet 55
Width, feet 13
Filter Surface Area, Total, ft2 1430
Filtration Rate at Design Flow of 6.2 MGD, GPM/ft2 3.0
Chlorine Contact Basins
Number 1
Dimensions
Diameter, feet 55
Sidewall Water Depth, feet 9.3
Volume, gal. 165280
Detention Time at Design Flow of 6.2 MGD, min. 38
Flow Equalization Basins
Number 2
Dimensions
Length, feet 210/275
Width, feet 144.5/200
Depth, feet 7/5
Bottom Slope, H:V 2:1
Volume, each, mil. gal. 1.3/1.8
Total Volume, mil. gal. 3.1
Chlorine Feed Facilities
Scales
Number 1
Type Enclosed box
Capacity 4 - One Ton Cylinders
Chlorinators
Number 3
City of High Point - Westside WWT"P Evaluation
- 16-

TABLE 3.5 - EXISTING FACILITIES, DESIGN DATA (Continued)
Type
Capacity, each
Chlorine Storage Area
Number of Cylinders
Sludge Thickener
Type
Surface Area
Solids Loading Rate
Solids Capacity
450 lbs/hr.
Hydraulic Capacity
Thickened Sludge Pumps
Type
Number
Capacity, each
Drive Size
Sludge Digester
Type
Number
Dimensions
Type of Cover
Volume
Sludge Blending Tank
Dimensions
Diameter, ft.
Sidewall water depth, ft.
Volume, gal.
Mixing System
Quantity
Type
Capacity, each, GPM
Motor Horsepower
Sludge Grinders
Number
Type
Size, inches
Capacity, GPM
Motor horsepower
Digester Mixing Equipment
Type
Number of Mixed Digesters
Free Standing, Pressure,
Manual Control
500 lbs/day
10 - One Ton Cylinders
Dissolved Air Flotation
2,380 SF
0.19 lbs/SF/hr.
180 GPM
Progressive Cavity
2
45 - 210 GPM
20 Hp
Anaerobic
1
70'x26'SWD
Floating
748,000 gallons
70
26
748,000
3
Submersible
12,700
15
2
In -line
4
200
3
Gas recirculation, center tube
1
City of High Point - Westside WWFP Evaluation
- 17-

TABLE 3.5 - EXISTING FACILITIES, DESIGN DATA (Continued)
Number of Gas Compressors
Drive Size, each
Sludge Recirculation Pumps
Type
Number
Drive Size
Capacity, each
Sludge Heater
Type
Capacity
Primary Fuel
Sludge Heating Capacity
Energy Recovery System
Type
Number
Engine
Type
Primary Fuel
Drive Engine Size
Generator
Type
Rating
Belt Filter Press
Size of Belt
Number
Hydraulic Capacity
Solids Loading Capacity
Solids Production Rate (90% Capture)
Sludge Feed Pumps
Type
Number
Capacity, each
Drive Size, each
Centrifuge
Number
Type
Capacity, GPM
Solids Capacity, lb/hr.
2
25 Hp
Centrifugal
2
10 Hp
550 GPM
Combined Boiler and
Heat Exchanger
1,125,000 BTU/hr.
Digester gas
90°F
Engine -driven induction
generator with engine and
exhaust heat recovery
2
Spark ignited
Digester gas
150 Hp
Squirrel cage induction motor
100 KW
2.0 meters, max.
1
90 GPM
1,300 lbs/hr.
1,170 lbs/hr.
Progressive cavity, variable speed
2
45 - 210 GPM
20 Hp
1
Horizontal, solid bowl
125
2,500
City of High Point - Westside WWTP Evaluation
- 18-

TABLE 3.5 • EXISTING FACILITIES, DESIGN DATA (Continued)
Solids Capture %
Dewatered Cake %
Polymer Dosage, lb/ton of Dry Solids
Dewatered Cake Screw Conveyor
Number
Capacity, ft3/hr.
160
Motor Horsepower
Dewater Cake Conveyors
Number
Type
Belt Width, inches
Belt Speed, FPM
Capacity, tons/hr.
Cake Storage Hopper
Number
Live Bottom Screws
Quantity
Storage Capacity, ft3
pH Control Facilities
Type
Feed Points
Bulk Lime Storage Hopper
Number
Capacity
Dry Lime Feeders
Number
Type
Capacity (Pebble Quick Lime)
Lime Slakers
Number
Type
Capacity (Pebble Quick Lime)
Lime Slurry Tank
Number
Type
Volume
Mixer type
Rating
95
30
17
1
3
2
Belt
24
20
4
1
3
600
Quick lime feed
Aeration basin influent, primary
clarifier, scum well,
DAF inlet and sludge well
1
2,000 cf
2
Volumetric, helical feed
500 lbs/hr.
2
Detention or paste
500 lbs/hr.
1
Reinforced concrete
5,425 gallons
Axial flow
5 Hp
City of Nigh Point - Westside WWTP Evaluation
- 19-

TABLE 3.5 - EXISTING FACILITIES, DESIGN DATA (Continued)
Lime Slurry Feed Pumps
Number 3
Type Progressive cavity
Capacity, each 120 to 900 GPH
Drive 5 Hp
Type Variable speed
Process Water Pumps
Type Vertical turbine
Number 2
Capacity, each 750 GPM © 123' TDH
Drive Size, each 30 Hp
i
City of High Point - Westside WHIP Evaluation
- 20 -

4.1 GENERAL
The evaluation of alternatives for expansion and upgrade of the Westside Plant is based on the
following:
•
.
.
.
.
.
Past performance of the treatment facilities.
The ability to meet more stringent effluent requirements for conventional pollutants,
including BODS and ammonia.
The ability to meet projected stringent nutrient removal requirements.
Hydraulic considerations with emphasis on providing capacity for peak flows and
positive flow distribution among operating units.
Operational reliability and flexibility.
Future expansions and improvements beyond the scope of this study.
Input from City Staff.
These improvements have been divided into three areas including interim and upgrade/expansion needs.
4.2 INTERIM NEEDS
This section addresses several items which are being, or will likely be, addressed prior to the plant
expansion project. In general, these items can be funded from the capital improvement plan or possibly regular
O&M budgets. The disinfection upgrade is already funded from 1992 Bond funds.
Flooding Problem
During the heavy rains just prior to Hurricane Fran in the Fall of 1996, several of the buildings were
flooded. The blower building had approximately a foot of water inside, which resulted in an elevation of 711.5
t. Although available data in north High Point indicated this was a 100 year storm, this significantly exceeds
the FEMA flood elevations for the site which are as follows:
Flood Event Elevation
10 year 704.0
50 year 705.3
100 year 706.0
500 year 707.5
The major damage from the 1996 flood occurred in the basements of the primary, secondary, and
blower buildings, and to electrical gear throughout the plant. All basin walls are at or ajove elevation 711.0
except for the influent pump station (710.5) and chlorine contact and DAF basins (710 ±). However, the floor
elevations of the blower building and primary and secondary sludge pump buildings are at 710.5. The main
power feed and switchgear are also located adjacent to the blower building and is at elevation 710 ±.
City of High Point - Westside WWTP Evaluation - 21 -

Because of the great expense associated with floodproofing of these structures, it is recommended to
concentrate floodproofing efforts in improving the condition of the adjacent streams. Inspection of Rich Fork
Creek shows heavy siltation within the channel which contributed to this flooding problem.
It is also recommended to relocate electrical gear above elevation 711.5, where feasible, as part of
regular maintenance activities or to install watertight replacements where possible. Future facilities should be
constructed with walls above 711.0 where feasible, and location of future electrical equipment should be as high
as possible.
Plant Headworks
City employees have fabricated a cover to prevent the grit auger from freezing. A cover for the entire
headworks structure would not be feasible due to the extremely high cost involved and resultant difficulty in
accessing equipment. Future upgrades should include provisions to reduce the freezing problems, such as
insulated covers, etc.
The existing grit removal system is in good mechanical condition. When the buckets are cut off for
maintenance, grit builds up around the buckets and the chains have a tendency to break when restarted. Two
possible solutions would be to cut a V-notch channel below the buckets to allow grit settlement or install a jet
system to suspend the grit prior to restarting the buckets.
The screw pumps have had problems in the past with drives and bearings. These should be inspected
to determine if the lower bearings or drives need rebuilding or replacing.
Chemical Phosphorus Removal
Phosphorus is found in two forms in raw municipal wastewater: polyphosphate and orthophosphate.
Polyphosphates are soluble compounds that pass through primary treatment into the secondary process where
biological enzymatic activity converts them to the orthophosphate form. Orthophosphates will pass completely
through primary and secondary processes and appear in the final effluent if not converted to an insoluble
precipitate, which can be settled out. The phosphorus is removed from the wastewater in the settled sludge.
To enhance the formation of the precipitated phosphorus, chemicals such as alum or ferric chloride are
added to primary and/or secondary clarifier influent flow. The proposed system will include storage and
feeding facilities capable of supplying chemical solution to achieve a 2 mg/1 total phosphorus limit.
TABLE 4.1
PHOSPHORUS REMOVAL COST SUMMARY
Construction Costs
Chemical System $234,200
Related Cost $39.200
Total $273,400
Annual Operating Costs
Alum and Electrical Cost $80,000
City of High Point - Westside WWTP Evaluation
- 22 -

The plant expansion proposed will include biological nitrogen and phosphorus removal. With the 1998
total phosphorus limit of 2 mg/1 approaching, a chemical phosphorus reduction system is being installed. It
will be used until the plant is expanded, at which time it will be used as a polishing phosphorus reduction
system to meet the 0.5 mg/L limit, and a backup.
DISINFECTION
The existing chlorine storage and feed facilities consist of three chlorinators rated at 500 lb/day each,
one four single ton container scale and storage for ten ton containers. The existing chlorine contact tank has
a total volume of 165,000 gallons.
Review of plant monitoring data for the period of January, 1993 through June, 1996 indicates an average
effluent chlorine dosage of 1.8 mg/1 and a maximum month chlorine dosage of 3.0 mg/1. The maximum
recorded daily chlorine use for the period was 158 pounds and the maximum daily chlorine dosage rate was
4 mg/1. The adequacy of the existing facilities was reviewed based on a maximum daily dosage rate of 4 mg/1
and a maximum monthly dosage rate of 3 mg/1.
Based on a process peak flow of 23.25 MGD and a chlorine dosage rate of 4 mg/1, the maximum
chlorine demand is 775 lb/day. Given the maximum allowable withdrawal rate from a ton container of 400
lb/day, the four manifolded ton containers have a maximum capacity of 16001b/day. Given that the maximum
daily chlorine use for the above period was 158 pounds, the existing ton container facilities would be adequate
for the expanded flow.
Based on the design flow of 9.3 MGD and a maximum month chlorine dosage of 3.0 mg/1, the existing
ton container storage facilities provide for an adequate chlorine supply of over a month. No additional storage
space is required.
Regulations require 15 minutes of chlorine contact time at peak flow or 30 minutes at permitted
maximum month flow, whichever results in the greater contact volume. The existing chlorine contact tank
would have a contact time of 10 minutes at the process peak flow of 23.25 MGD. Additional chlorine contact
tanks with a volume of 115,000 gallons will be required.
Three alternatives were considered for increasing disinfection capacity and for providing dechlorination
at the Westside Wastewater Treatment Plant. The plant currently disinfects with gaseous chlorine and is not
required to dechlorinate under the present NPDES permit. However, dechlorination will be required if a
chlorine -based disinfectant is used for the proposed plant expansion. Alternative 1 is based on the continued
use of gaseous chlorine for disinfection and the use of gaseous sulfur dioxide for dechlorination. Alternative
2 is based on the use of liquid sodium hypochlorite for disinfection and liquid sodium bisulfite for
dechlorination. Alternative 3 is based on the use of ultraviolet disinfection.
City of High Point - Westside WWTP Evaluation
- 23- -

The following cost assumptions are used for the valuation of the alternatives. Annual operating costs
include estimated costs for chemicals, power, and labor. An average rate of $20 per hour is used to estimate
labor costs. Power costs are estimated at $0.05 per KW-hr. Unit costs for chemicals are listed as follows:
Chlorine Gas
Sulfur Dioxide Gas
Liquid Sodium Hypochlorite
Liquid Sodium Bisulfite
$0.23 per pound
$0.20 per pound
$0.50 per pound (15%)
$0.24 per pound (38%)
. The present worth cost of each alternative is estimated based on a 20 year design life and an interest
rate of 8 percent.
Alternative 1: Gaseous Chlorine and Sulfur Dioxide
Since the City currently utilizes chlorination as the means of disinfection consideration must be given
to its continued use followed by chemical dechlorination. The continued use of the toxic chlorine gas will
produce chlorine residuals that are very toxic to some aquatic species at very low concentrations. The toxic
byproducts of chlorine compounds may be carcinogenic and can accumulate in aquatic organisms and adversely
affect the quality of downstream public water supplies. Dechlorination by adding another toxic gas, sulfur
dioxide, can remove the chlorine residuals, but will not neutralize all compounds formed during the disinfection
process.
Dechlorination facilities necessary would include ton cylinder handling and storage facilities, as well
as sulfur dioxide feed equipment similar to those associated with the chlorination system. The sulfur dioxide
solution could be injected in a small structure downstream of the chlorine contact basin. Continuous chlorine
residual monitoring equipment would be required to automatically adjust chlorine and sulfur dioxide solution
feed rates to adequately reduce micro-organism levels while minimizing potential toxicity problems. A gas
scrubber system is recommended for neutralizing chlorine gas in the event of a leak, and is likely that one may
be required under future regulations.
A new chlorine contact tank would have to be constructed to provide, in combination with the existing
tank, 15 minutes of contact time at a flow of 23.25 MGD.
City of High Point - Westside WWTP Evaluation
- 24 -

TABLE 4.2
GASEOUS CHLORINATION/DECHLORINATION COST SUMMARY
Construction Cost
Chlorine Contact Tanks $200,000
S itework $50,000
Chlorine Building Modifications $150,000
Dechlorination Building $230,000
Chlorine Gas Scrubber $250,000
Yard Piping $75,000
Miscellaneous Structures $75.000
Total $1,030,000
Annual Operating Cost
Chemical Cost for Chlorine $25,000
Chemical Cost for Sulfur Dioxide $3,700
Labor $28,500
Safety Equipment and Training $30,000
Total $87,200
Present Worth of O&M Cost $856,000
Total Present Worth Comparative Cost $1,886,000
Alternative 2: Liquid Sodium Hypochiorite and Sodium Blsulfite
Under Alternative 2, the existing chlorine building would be renovated to house a metering pump room.
A new bulk storage facility will be constructed for storage of liquid sodium hypochlorite and sodium bisulfite.
A chlorine contact tank of the same size and configuration as in Alternative 1 will be constructed. Although
sodium hypochlorite is less hazardous than gaseous chlorine, sodium hypochlorite also poses some safety
concerns. Both sodium hypochlorite and sodium bisulfite are corrosive chemicals; therefore, safety is a concern
for operators who supervise the transfer and metering of the chemicals. Another problem is that sodium
hypochlorite decomposes over time. Decomposition occurs more rapidly when the concentration is high, when
the temperature is high, and when the solution is exposed to light.
TABLE 4.3
LIQUID CHLORINATION/DECHLORINATION COST SUMMARY
Construction Costs
Chlorine Contact Tank $200,000
Sitework ; $70,000
Bulk Storage Facility and Pump Room $350,000
Yard Piping $75,000
Miscellaneous Structures $75,000
Total Cost $770,000
City of High Point - Westside WWTP Evaluation
- 25 -

Annual Operating Costs
Chemical Cost for Sodium Hypochlorite $31,000
Chemical Cost for Sodium Bisulfite $3,200
Labor $20,000
Safety Equipment and Training $10.000
Total Cost $64,200
Present Worth O&M Cost $630,322
Total Present Worth Comparative Cost $1,400,322
Although the safety concerns are abated with hypochlorite, the issue regarding toxicity and cyanide
production still remain with this option.
Alternative 3: Ultraviolet Disinfection
Ultraviolet disinfection pilot testing was performed at Westside during October, 1995 and the effluent
responded well to ultraviolet disinfection dosing. A conservative transmittance value of 50 percent was used
for analysis. Additional testing may indicate a higher transmittance value may be used for design, thus
reducing the cost.
The ultraviolet disinfection equipment would include high output lamps with automated cleaning cycles
and flow -paced controls to regulate power usage. There are two manufacturers offering high intensity UV
systems. Although there is some penalty in electrical costs over conventional low intensity systems, these
designs reduce lamps by a factor of over 15:1. The higher intensity systems also offer significant advantages
in penetration of low transmittance (less than 60%) wastewater, as encountered here. The power outfit of the
lamps would be variable to provide additional control of power consumption. The existing chlorine system
would be abandoned with a small chemical system for backup. The existing chlorine contact basin could then
be converted to a second DAF unit upon plant expansion.
TABLE 4.4
UV COST SUMMARY
Construction Costs
Ultraviolet Disinfection Equipment $660,000
Yard Piping/Site Work $135,000
Associated Equipment $97,000
Structure $88,000
Electrical $70,000
Total $1,050,000
Annual Operating Costs
Power Cost $38,900
Lamp & Misc. Replacements $18.270
Total $57,170
Present Worth O&M Cost $549,150
Total Present Worth Comparative Cost $1,599,150
City of High Point - Westside WWTP Evaluation
- 26 -

These costs are representative of two UV channels and two disinfection modules using the Trojan
UV4000 system. Proposed improvements include construction of two channels, the initial installation of one
UV module, and associated electrical and piping work. The expanded facility would require only the
installation of additional lamp modules.
TABLE 4.5
COST COMPARISON OF DISINFECTION ALTERNATIVES
Cost for the three alternatives are summarized below:
Alternative 1
Construction Cost $1,030,000
Present Worth O&M Cost $856,000
Total Present Worth Comparative Cost $1,886,000
Alternative 2
Construction Cost $770,000
Present Worth O&M Cost $630,322
Total Present Worth Comparative Cost $1,400,322
Alternative 3
Construction Cost $1,050,000
Present Worth O&M Cost $549,150
Total Present Worth Comparative Cost $1,599,150
Ultraviolet disinfection would minimize safety concerns and eliminate the potential for effluent toxicity
associated with the use of chlorine. Based on these factors, ultraviolet disinfection is recommended for the
proposed upgrade and expansion of the Westside Plant.
EFFLUENT FILTERS
The filters have been one of the most troublesome processes at the Plant. Recent repairs and changes
to the backwash pumps seem to have remedied some of these problems. At present, the filters bypass at flows
of 7-9 MGD. This would indicate that the existing filters are not adequately sized to handle peak flows. Also,
plant operators have expressed some need to have the traveling bridge mechanism rebuilt.
Alternatives have been reviewed for upgrade/replacement of the existing filters to a more reliable,
economical system. The DAVCO Gravisand filter is an improved two pump traveling bridge filter. (TBF)
designed for retrofitting and upgrading existing TBF's. A tubular underdrain header replaces the porous plate
underdrain which eliminates media leakage and biological fouling. The bridge mechanism stops over each cell
during backwash. Once the cell has been washed, the pump is de -energized. This allows the fluidized media
to settle and prevents media migration. The Gravisand filters can be retrofitted to existing tankage so no new
structures are necessary. The existing filters can be replaced with Gravisand filters as an interim improvement
for approximately $300,000.
City of High Point - Westside WWTP Evaluation
- 27 -

ACCESS TO PRIMARY AND SECONDARY BUILDINGS
At present, access to the primary and secondary solids buildings via the monorail is limited. The
existing monorails do not extend far enough outside. This prevents personnel from loading heavy equipment
directly from the monorail to a truck. As a remedy, the monorails could be extended by constructing an
additional support structure outside and providing an additional length of railing. This work could be completed
as an interim improvement or as part of the plant expansion.
STANDBY POWER SYSTEM
The existing NPDES permit does not require a standby power system. The existing NPDES permit for
the plant states the City is responsible for preventing the discharge of inadequately treated waste during power
outages by standby power generators or the retention of inadequately treated effluent. Current State regulations
require either dual electric power sources or an automatically activated standby power system capable of
providing power to all essential treatment components during periods of primary power outages. It is
anticipated that a secondary power source other than electricity will be required by year 2003. Proposed House
Bill 215 will require any wastewater system for which a permit for facilities discharging to the waters of the
State is required shall not be operated unless a generator that is operated by a source of power other than
electricity is maintained on -site.
The existing plant's primary power supply is a 480 volt, 3 phase system for the larger drive motors and
includes step down transformers for 240V and 120V circuits. The largest drive motors are 100 Hp which are
located at the influent pump station and at the blower building. Numerous other smaller motors are located
throughout the plant site. In order to provide essential treatment, the standby power system must be sized to
allow all treatment components to be operable during primary power outages. At a minimum, the standby
power system would require the installation of a single 1500 KW diesel driven generating unit, switchgear
modifications, and wiring renovations. A second generating unit may become necessary after the plant is
expanded.
TABLE 4.6
STANDBY; POV1WER SYSTEM `2
Estimated Construction Cost
Equipment
Installation & Wiring
Total Construction Cost
Estimated Project Cost
Construction Cost
Technical Services, & Construction Contingencies
TOTAL PROJECT COST
$550,000
$200,000
$750,000
$750,000
$150,000
$900,000
City of High Point - Westside WWTP Evaluation - 28 -

4.3 EXPANDED FACILITIES
Based on results from the workshop, the plant expansion has been sized to treat an average daily flow
of 9.3 MGD, with corresponding peaks of 23.25 MGD for process design and 27.9 MGD for hydraulic design.
The expanded facilities should be designed for nutrient removal in light of the proposed limits.
Preliminary and Primary Treatment Facilities
The existing preliminary and primary treatment facilities consist of one mechanical bar screen, a Parshall
flume, two aerated grit chambers, two primary clarifiers, and primary solids pumping facilities. Based on City
Staff input at an October workshop, the major equipment has generally been working well. The existing
facilities were evaluated for peak flows associated with the proposed plant expansion to 9.3 MGD.
The existing bar screen is working well except in freezing weather. A plant expansion will require a
second screen be installed in the existing bypass channel. In any case, the screens need to be covered to
resolve the freezing problem.
The existing aerated grit chambers will pass the 23.3 MGD peak flow with a detention time of 2
minutes. The 2 minute detention time is on the low end of the recommended detention range for aerated grit
chambers (2 to 5 minutes) at peak hourly flows. At the design flow of 9.3 MGD, detention time increases to
6 minutes. The existing facilities may be utilized for an expanded plant flow of 9.3 MGD, but grit removal
efficiency may be reduced at higher flows.
Two concerns associated with the existing grit facilities were raised by City Staff. First, during winter
months, the grit conveyors tend to freeze up when not in use. As an interim measure, it is recommended to
insulate the augers as a maintenance item. Future projects should consider replacement with belt conveyors
or other improvements. Second, when the bucket system is not in operation, grit builds up quickly. This build-
up makes the bucket start up virtually impossible without manually removing the grit before restarting. The
only solution for this is to operate the grit removal system at more frequent intervals to prevent overloading.
Future remedies could include a jet system to resuspend the grit, or possibly a small trough and drain line could
be installed to facilitate cleanout.
The parshall flume will need to be upgraded for increased flow measurement, as well as replacing
instrumentation. The existing flume is rated at 21.4 MGD and future hydraulic concerns will necessitate lower
headloss. It may be possible to incorporate flow measurement and primary clarifier flow splitting and reduce
overall head loss.
The two existing 70-foot diameter clarifiers would have a surface overflow rate (SOR) of 1208 GPD/SF
at the design flow rate of 9.3 MGD. This exceeds the value normally designed for of <1000 GPD/SF. One
additional 70-foot diameter clarifier is required to provide a SOR of 806 GPD/SF at the design flow rate of
9.3 MGD.
City of High Point - Westside WWTP Evaluation
- 29 -

The existing primary solids pumps are inadequate to handle the increased volume associated with
expansion. These existing pumps should be replaced with larger capacity pumps during renovations of the
primary solids building to accommodate the three clarifiers.
Flow Equalization
No modifications are proposed to the flow equalization basins, as recently installed piping has increased
operating flexibility of the basins.
Activated Sludge Facilities
The existing activated sludge facilities are designed for a process flow of 6.2 MGD and a peak process
flow of 12.4 MGD. Modifications to the existing facilities will be required to provide capacity for the proposed
expanded design flow of 9.3 and are also necessary to meet nutrient limits.
The existing activated sludge facilities are designed for year-round nitrification to meet current monthly
ammonia limits of 2 mg/1 in the summer and 4 mg/1 in the winter. Speculative limits have been requested but
none have been provided by the State. The following limits are based on proposed limits at Eastside WWTP
and will be revised once the State provides speculative limits for Westside.
Parameter
TABLE 4.7
Current Limits
Speculative Limits
Flow, MGD
6.2
9.3
BOD5, mg/1
5.0 (summer)
10.0 (winter)
5.0
5.0
NH3-N, mg/1
2.0 (summer)
4.0 (winter)
1.0
2.0
Total Phosphorus, mg/1
2.0 (1998)
0.5
Total Nitrogen, mg/1
N/A
4.0 (summer)
8.0 (winter)
Significant modifications to the existing facilities will be required to meet the proposed total nitrogen
limits, as well as the proposed total phosphorus limit as previously mentioned. This will require the chemical
process to be installed prior to the upgrade/expansion which will include biological phosphorus removal.
Processes for removing nitrogen, as well as phosphorus from wastewater, are available for meeting the
speculative limits at the proposed design flow of 9.3 MGD. Limited site area, future expansion considerations,
as well as maintenance of existing plant operations during construction all play a role in the facility design for
nutrient removal at the Westside Plant.
Biological nutrient removal (BNR) processes can be utilized to remove both phosphorus and nitrogen
to low effluent levels without the use of chemicals and the associated increases in waste sludge production,
City of High Point - Westside WWTP Evaluation
- 30 -

oy
oxygen requirements, and operational costs. It is possible to implement either biological phosphorus removal
(BPR) or biological nitrogen removal separately, but the processes are more stable, efficient, and economical
when implemented together. In many cases, BPR can be achieved by simply adding an anaerobic zone to the
biological nitrogen removal process.
BNR processes include activated sludge process modifications which consist of alternating anaerobic,
anoxic, and aerobic zones to promote biological nutrient removal. By definition, an anaerobic zone is totally
devoid of free oxygen, an anoxic zone uses nitrate -nitrogen in the absence of oxygen, and the aerobic zone
maintains a free oxygen concentration.
Typically, BNR process consists of at least 3 separate stages. In the first stage of the process, anaerobic
conditions are provided which promotes the release of phosphorus from the activated sludge organisms. In the
second stage, anoxic conditions are provided for the conversion of nitrate to nitrogen gas. In the aerobic zone,
BOD is oxidized, ammonia is converted to nitrate by nitrifying organisms, and phosphorus uptake occurs.
Recycle is provided from the aerobic zone to the anoxic zone for denitrification of the nitrates formed in the
aerobic zones.
In order to implement BNR processes, more detention time will be required which means larger basins
are required. While required detention times vary between BNR processes, typically 5 to 14 hours at design
flow is necessary. For this report and associated cost estimates, a total detention time of 13.4 hours has been
used. Final design using additional nitrogen monitoring data will refine the actual volumes to be provided.
The existing aeration basins are well suited to be retrofitted into the required anaerobic, anoxic, and
aerobic zones as they are long and narrow. The zones can be created by modifying aeration piping, adding
gates and baffle walls, and adding mixing equipment. The existing basins are 0.76 MGD each, for a total
volume of 2.29 MGD. At the current design flow of 6.2 MGD, this is an 8.8 hour detention. Even with
modifications to provide the different zones, it is unlikely that this volume could provide consistent compliance
with the 2003 nitrogen limits. A fourth basin, similar in size to the existing basins, would provide about 11.8
hours detention at 6.2 MGD. However, at the expanded capacity, an additional 2.9 MG would be necessary
to provide the design detention time.
The processes which are considered for BNR are outlined as follows:
Vip Process
The Virginia Initiative Process (VIP) was developed at the Hampton Roads Sanitation District (HRSD)
and has been made available for public use with no license requirement or patent fees. The VIP process is a
conventional BNR process very similar to the University of Cape Town Process (UCT) with the biological
phosphorus release mechanism occurring in the main flow train of the treatment process. In the UCT/VIP
process, the primary clarifier effluent first enters the anaerobic stage of the biological treatment process so that
City of High Point - Westside WWTP Evaluation
- 31 -

influent BOD5 and volatile fatty acids can be utilized to fuel the anaerobic phosphorous release mechanism in
the biological phosphorus release -uptake cycle. The waste stream then flows into the anoxic stage for
denitrification and BOD5 removal. Nitrification, phosphorus uptake and further BOD5 removal occur in the
anaerobic stage.
Nitrified mixed liquor is recycled from the aerobic stage to the anoxic stage to allow denitrification.
Sludge from the secondary clarifier is returned to the anoxic stage to allow denitrification of this stream and
avoid nitrate addition to the anaerobic stage. Mixed liquor is recycled from the anoxic stage to the anaerobic
stage to provide a denitrified mixed liquor to the anaerobic stage. The system can also be operated as a two -
stage system without an anaerobic stage.
Sequential Step Feed
The sequential step feed nitrification/denitrification process provides multiple anoxicjoxic reactors in
series. Operating experience with sequential step feed is limited. The process does not typically use internal
recycle, rather the influent flow is fed in steps to the beginning of the anoxic zones to provide a carbon source
to drive denitrification. Methanol may be added in the third anoxic zone to achieve low effluent nitrogen
values.
The main advantages of the step feed process are that it does not require recycle, there is potential for
greater nitrogen removal than the VIP and modified UNC processes, and tank volume requirements may be
reduced. The disadvantage is its limited operating experience.
Modified Unc Process
The Modified UNC Process is a modification of the sidestream biological phosphorus removal process
which was developed by Dr. Donald Francisco and Dr. James Lamb at the University of North Carolina at
Chapel Hill. In this process, the biological phosphorus release mechanism occurs in a sidestream anaerobic
stage and the main process flow train is not treated in an anaerobic stage. The modified UNC process is a
derivation of the original UNC Process with the addition of a recycle stream for denitrification in an anoxic
stage at the beginning of the main wastewater flow train. In the Modified UNC process, the primary clarifier
effluent entering the biological treatment process flows first to the anoxic stage where influent BOD5 is used
to fuel denitrification. The waste stream then flows to the aerobic stage for nitrification, phosphorus uptake,
and then to the secondary clarifier. Mixed liquor is recycled from the aerobic stage to the anoxic stage for
denitrification. The return sludge from the secondary clarifier is pumped to a sidestream anaerobic stage where
the release phase of the phosphorus release -uptake cycle occurs. Fermented primary sludge is added to this
stage to provide volatile fatty acids for the phosphorus storing organisms. The anaerobically treated return
sludge then flows to the anoxic stage where it is combined with primary effluent.
City of High Point - Westside WWTP Evaluation
- 32 -

An advantage of the Modified UNC Process is that the anaerobic stage is incorporated into the return
sludge stream rather than receiving the full influent flow as in the VIP process. This protects the anaerobic
stage and the phosphorus release -uptake mechanism from upsets due to fluctuations in influent and organic
loading and requires less anaerobic tankage. The process should be configured in 5 stages. The 5-stage
configuration adds a second anoxic zone to achieve higher levels of TN reduction, which will be necessary with
the proposed 4 mg/L nitrogen limit.
Effluent Filters
Plant expansion will also require the addition of effluent filters. The existing filters are gravity,
continuous backwash type filters. It is recommended that additional filters, similar in design and size to the
retrofitted Gravisand TBF's, be added to accommodate larger flows and maintain the current loading rate.
Solids Handling
The recent sludge handling and dewatering facility renovations included the conversion of an existing
anaerobic digester to a sludge blending tank, installation of three submersible mixers, two grinders, a dry solids
centrifuge, a cake storage hopper, and an additional truck loading conveyor. The dewatered cake is loaded onto
a truck or stored in a hopper and transported to Eastside. Once the incinerator at Eastside is placed on-line,
the remaining anaerobic digester at Westside can be taken out of service and renovated to serve as a second
mixing/holding basin. These renovations would include the installation of three submersible propeller mixers
to provide a homogenous sludge supply for the dewatering system. As flow increases, additional operating time
of the centrifuge will be required. Also, the addition of a second centrifuge should be considered for backup
and alternating use.
Solids Thickening
At the existing facilities, waste activated sludge (WAS) is thickened by a single 55 foot diameter
dissolved air flotation (DAF) thickener. WAS thickening reduces the volume of secondary solids by
concentrating the relatively dilute solids from the return activated sludge flow stream. This reduces costs of
pumping, increases detention time in downstream storage tanks, and reduces solids dewatering costs.
The installation of the ultraviolet disinfection facilities will discontinue use of the existing chlorine
contact basin. Westside's WAS thickening capabilities can be increased with the conversion of the chlorine
contact basin to a DAFf thickener. This will serve as a backup to the existing DAF and will be necessary to
handle the sludge from the BNR process and expanded plant flows.
Summary
The following table lists the proposed improvements and estimated costs associated with the previously
addressed plant upgrade and expansion from 6.2 MGD to 9.3 MGD. These improvements represent the most
cost-effective approach for providing additional treatment capacity at the Westside Plant.
City of Nigh Point - Westside WWTP Evaluation
- 33 -

A proposed plant site plan is shown on Figure 4.1.
TABLE 4.8
PROPOSED IMPROVEMENTS AND ESTIMATED CONSTRUCTION COSTS
BNR UPGRADE AND EXPANSION TO 9.3 MGD
_�. � ..i Tyr � m x. � i'riy'�bdi9rta� ,..mi ur ,u'... •
Proposes# Improvements �t.T`L." �f+° <{�{.:.,,�',.i'+F timatect Cost
'3:fiiw.ii.lr-.....
Preliminary/Primary Treatment
New bar screen $ 150,000
New primary clarifier 275,000
flow splitter / measurement 125,000
Primary sludge pump upgrade 150,000
BNR facilities
Basin structural renovations 300,000
Additional basin structure 2,300,000
Mixing / aeration equipment 850,000
Blower improvements 200,000
Nitrified recycle pump station 900,000
Other Process
Secondary clarifier 775,000
Sludge return pump upgrades 100,000
New effluent filter 550,000
Additional UV modules 700,000
Sludge Thickening
Demo CCT 75,000
Dome Cover 125,000
DAF equipment 300,000
Sludge pump replacement 125,000
Building Modifications 100,000
Sludge Dewatering
Convert Digester to Mixing Tank 400,000
New centrifuge & accessories 650,000
Miscellaneous
Sitework • 150,000
Yard Piping 700,000
Electrical 500,000
Distributed Control System 250,000
Estimated Construction Cost $ 10,750,000
Related Costs
Technical Services (10%) 1,075,000
Contingencies (10%) 1,075,000
Total Estimated Project Cost $ 12,900,000
City of High Point - Westside WWTP Evaluation
- 34 -

PROPOSE')
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CITY OF HIGH POINT
WESTSIDE WWTP EXPANSION
OVERALL SITE PLAN
DAVIS-MARTIN-POWELL
& ASSOCIATES, INC.
ENGINEERING - LAND PLANNING - SURVEYING
HIGH POINT. NORTH CAROLINA