NC0055786_Report_20020201

NPDES DOCUMENT SCANNING: COVER !SHEET
NPDES Permit:
NC0055786
Lexington Regional WWTP
Document Type:
Permit Issuance
Wasteload Allocation
Authorization to Construct (AtC)
Permit Modification
Complete File - Historical
Engineering Alternatives (EAA)
Correspondence
Owner Name Change
(-ger; r-/- /
Instream Assessment (67b)
Speculative Limits
Environmental Assessment (EA)
Document Date:
February 1, 2002
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Lexington Regional
Wastewater Treatment
Plant
City of Lexington
Lexington, North Carolina
NPDES Permit No. NC 0055787
Hydraulic Analysis and
Nutrient Removal Study
February 2002

Lexington Regional
Wastewater Treatment Plant
City of Lexington
Lexington, North Carolina
NPDES Permit No. NC 0055787
Hydraulic Analysis and
Nutrient Removal Study
February 2002
*Pease
Architects -Engineers
FINAL DRAFT
Issued for Review Purposes Only

HYDRAULIC ANALYSIS
Hydraulic Capacity
Table 1
Table 2
Hydraulic Profile
Table 3
Conclusions
NUTRIENT REMOVAL
Table of Contents
Plant Design Flow Summary
Summary of Existing Influent and Effluent Process Control
Data
Unit Process Hydraulic Analysis
Process Modifications — 6.5 MGD Upgrade
BNR Upgrade
Biosolids Dewatering
Solid Contact Reactor
Chemical Feed System
Table 4 Estimate of Probable Project Costs
Process Modifications — 8.25 MGD Upgrade
Table 5 Estimate of Probable Project Costs
Alternate Process Modifications
Table 6 Estimate of Probable Project Costs

HYDRAULIC ANALYSIS
Hydraulic Capacity
The Lexington Regional Wastewater Treatment Plant (WWTP) was designed for an initial flow
of 5.50 million gallons per day (MGD). The design for the WWTP included provisions for
future increases in the capacity up to an ultimate average daily flow of 16.50 MGD.
The ultimate hydraulic design capacity for the plant is 36.7 MGD. The ultimate capacity is
based on applying a peaking factor of 2.22 to average daily flow of 16.5 MGD. Various
components of the plant including flow proportioning manholes and underground piping were
designed and constructed to accommodate the ultimate plant capacity.
Summaries of the original plant design flows are shown in Table 1.
Data for the actual influent and effluent flows for the period beginning June 1999 and ending
August 2001 is shown in Table 2.
The purpose of this analysis is to assess the resultant impact on the hydraulics of the existing
facilities caused by increasing the average daily flow by 1.0 MGD to total average daily flow of
6.5 MGD and a peak flow of 14.45 MGD.
An analysis was conducted by routing an average flow of 6.5 MGD and a peak flow of 14.45
MGD through the WWTP from the influent chamber of the first stage lift station to the effluent
discharge end wall at Abbotts Creek. Each unit process, manhole, weir and pipe was analyzed.
Record drawings of the existing facilities were utilized along with the original hydraulic
calculations.
Few modifications have been made to the plant since construction was completed in 1984. The
First and Second Lift Stations have been modified. The stations as originally constructed
utilized enclosed screw pumps as the primary pumping apparatus. Both lift station were
equipped with three (3) 54-inch diameter screw pumps. Each screw pump had a pumping
capacity of 6.19 MGD.
Two of the screw pumps operated as lead/lag pumps. The third pump was a standby pump
that operated in the event of a failure of the lead/lag pump.
Submersible pumps have been installed to replace two of the screw pumps at each station. One
screw pump has been retained at each station as a standby pump. The capacity of the
submersible pumps at each station is as follows:
First Stage Lift Station:
Submersible Pumps (Primary)
• 2 each © 2.89 MGD (2000 GPM)
• 2 each Q 4.32 MGD (3000 GPM)
Screw Pump (Standby)
• 1 each Q 6.19 MGD

Second Stage Lift Station
Submersible Pumps (Primary)
• 2 each @ 3.17 MGD (2200 GPM)
• 2 each @ 4.32 MGD (3000 GPM)
Screw Pump (Standby)
• 1 each Q 6.19 MGD (4300 GPM)
The results of the hydraulic analysis indicate that with minor modification the existing WWTP
can easily accommodate 1.0 MGD in crease in the average daily flow capacity.
A hydraulic profile is attached which shows the original elevations of the structures, weirs and
water surface elevations, invert elevations, etc. and the proposed changes in elevations resulting
from increasing the influent average daily flow from 5.50 MDG to 6.50 MGD. The increased
water surface level in most unit processes was less than 0.10 feet. All existing weirs have
sufficient head and freeboard to handle the increase in flow. The existing below ground and
above ground piping has adequate capacity. The underground piping consists primarily of
reinforced concrete pipe. A coefficient, C of 110 was calculated to read loss.
The minor modifications include the following:
• Increase the pumping capacity of the Second Stage Lift station by approximately
1050 GPM to handle peak flows
• Raise the Trickling (Roughing) Filter influent manhole approximately 1'6".
The need to raise the trickling filter influent manhole is based on a recirculation rate of 100°/a.
The plant currently operates without recirculation and anticipated changes in the plant process
to facilitate nutrient removal will probably eliminate the need to retain the recirculation
capability. Therefore, there may be no real need to raise the trickling filter influent manhole.
Simply replacing the impellers in the submersible pump with a larger impeller will provide the
required increase in the pumping capacity of the Second Stage Lift Pumps.
A future need to increase the pumping capacity was anticipated when the pumps were
purchased.
Aside from the changes in operating water levels as shown on the hydraulic profile, the
proposed 1.0 MGD increase in the influent flow rate will change the loading rates and detention
times of the various unit processes. These changes are summarized in Table 3.

Table 1: Lexington Regional Wastewater Treatment Plant Hydraulic Analysis
Plant Design Flow Summary*
(million gallonsyer day)
Line
Description
Avg.
Max
Hyd. Max.
1
Plant Influent
5.50
12.23
36.70
2
1st Stage Lift Station Effluent
5.50
12.23
36.70
3
2nd Stage Lift Station Influent
6.70
13.43
38.70
4
6.70
13.43
38.70
5
Primary Clarifier Influent
3.35
13.43
13.50
6
Primary Clarifier Effluent
3.05
12.83
12.90
7
Roughing Filter Influent -Effluent
5.80
18.33
18.40
8
Filter Recir. Pump Station Effluent
6.10
12.83
12.90
9
M.H. No. 3 Influent
6.10
12.83
38.70
10
M.H. No. 4 Influent
6.10
12.83
12.90
11
Aeration Tank - Influent
1.93
3.67
i,
3.70
12
Final Clarifier - Influent
5.80
18.33
18.40
13
Final Clarifier - Effluent
2.75
12.23
12.30
14
M.H. No. 6 Influent
8.25
12.23
25.60
15
M.H. No. 6 Effluent
5.50
12.23
36.90
17
Lagoon - Influent
2.25
6.12
12.30
18
Aeration Tank Pump Fac. - Effluent
2.88
19
20
Chlorine Cont. Tank - Influent
5.50
12.23
12.30
21
Plant Effluent
5.50
12.23
36.90
23
Raw Sludge Draw -Off
0.30
0.60
0.60
24
Raw Sludge
25
Digested Sludge
26
Digester Supernatant
0.60
0.60
0.60
27
Drying Beds Underdrain
0.60
1.40
1.40
28
Filter Recirculation
5.50
5.50
5.50
29
Activated Sludge Draw -Off
3.05
6.10
6.10
30
Activated Sludge Discharge
6.10
6.10
6.10
31
Return Activated Sludge
5.50
6.10
6.10
32
Waste Activated Sludge
0.60
6.10
6.10
33
Digester Supernatant
0.60
0.60
0.60
*JNPA Commission No. 5347 © 1983
Plant Flow Summary

Table 2: Lexington Regional Wastewater Treatment Plant Hydraulic Analysis
Summary of Existing Influent and Effluent Process Control Data
Month/Year
'=
EFF
FLOW
Average
INFLUENT
MIN.
INFLUENT
MAX
INFLUENT
FLOW
-
•
EFF
FLOW
Maximum
INFLUENT
MIN.
INFLUENT
MAX
INFLUENT
FLOW
EFF
FLOW
Minimum
INFLUENT
MIN.
INFLUENT
MAX
INFLUENT
FLOW
Jun-99
1.769
1.15
4.183
2.2
2.37
1.3
5.9_
2.64
' .
1.48
0.9
3
1.89
Jul-99
1.981
1.5
4.584
2.4729032
3.98
2.7
10
4.51
:
1.63
1
3.2
2.02
Aug-99
2.122
1.568
5.426
2.6996774
,- :
5.32
3
12
5.81
1.5
1.4
4
1.94
Sep-99
2.645
1.383
4.02
2.3331034
, .
4.12
2.2
5.8
3.46
=::;
1.91
1.1
3
1.01
0ct-99
3.008
1.416
4.845
2.7996774
_ .
6.17
2.4
10.4
5.4
2.06
1.2
4.1
1.68
Nov-99
2.604
1.35
4.433
2.633
4.9
2
10
4.83
2.19
1.2
3.2
2.24
Dec-99
2.718
1.484
4.474
2.718065
4.64
2.1
8.8
4.37
;::
1.46
1.2
3.2
2.22
Jan-00
3.131
1.661
5.035
3.0740968
. .
6.13
3.3
11.6
6.11,
'
2.16
1.3
4.1
2.18
Feb-00
3.32
1.903
4.99
3.2906897
;
5.81
2.8
10.8
5.62
; :
2.67
1.6
4.2
2.65
Mar-00
3.136
2.026
5.313
3.1463226
•
7.03
3.4
12.2
5.78
1.47
1.6
3.3
2.51
Apr-00
2.639
1.755
4.731
3.1503448
-
4.02
2.6
10.2
4.41
:
2
1.2
3.3
2.49
May-00
2.46
1.361
4.629
2.7629032
5.52
2.4
14.9
5.24
,=
2.03
1.1
3.6
1.94
Jun-00
2.29
0.997
3.67
2.2783333
2.81
1.2
4.4
2.73
' ;
1.92
0.8
3.3
1.98
Jul-00
2.179
1.216
3.894
2.3890323
2.99
1.9
6.9
3.25
: :
1.76
0.8
2
1.78
Sep-00
2.454
1.587
6.173
3.172333
:
3.606
2.4
14
4.408
;
1.765
1
4.4
2.466
Aug-00
2.241
1.584
5.094
2.9749355
.
3.474
2.6
8
4.055
1.753
1.4
4.1
2.589
Oct-00
1.697
4.697
2.55658061:
2.083
2.6
6.6
2.765
1.438
0
3.8
2.181
Nov-00
•
2.05
1.1
3.193
2.57
,
2.709
1.8
5.4
3.05
0.036
' 0.4
1
2.24
Dec-00
2.066
1.571
4.355
2.54
2.74
2
5.6
3.15.
1.64
1.4
3.6
2.14
Jan-01
2.15384
1.565
4.348
2.6144516
4.11
2.1
9
4.96
~
1.65
1.2
3.6
2.16
Feb-01
2.456
1.982
4.664
2.9264286
5.26
5.3
11.6
5.97
,;
1.8
1.8
3.8
2.33
Mar-01
2.946
1.913
5.368
3.3454839
6.66
4.8
12.8
6.57
1.99
1.6
3.3
2.44
Apr-01
2.553
1.713
5.24
3.07633333
3.77
2.2
8.8
3.94
1.97
1
3.4
1.77
May-01
2.345
1.806
4.81
2.9641935
3.93
2.4
7.3
4.24
=
2
1.7
4.4
2.68
Jun-01
2.217
1.71
4.423
2.861
2.89
2
7
3.33
1.76
1
3.3
2.52
Jul-01
2.198
1.665
4.961
2.8912903
3.24
2.4
7.8
3.74
1.71
1.2
4
2.42
Aug-01
2.057
1.752
4.694
2.8983871
.
3.05
2.8
10.8
3.64.5.
1.73
1.4
3.9
2.58
Source: Lexington Regional WWTP Process Control Monthly Reports

Table 3: Lexington Regional Wastewater Treatment Plant Hydraulic Analysis
Unit Process Hydraulic Analysis
Description
Plant Design Flow
• Flow Rates
24-Hour Average
8-Hour Maximum
4-Hour Maximum
Peak
• Wastewater
BOD5
Suspended Solids
Total Kjeldahl Nitrogen
Influent Lift Stations
First Stage Lift Stations
• Units
Submersible Pumps
Screw Pump (standby)
Second Stage Lift Station
• Units
Submersible Pumps
Original Design Basis
5.50 MGD
8.25 MGD
11.00 MGD
12.23 MGD
320mg/1
200 mg/1
25 mg/1
2 each @ 2.89 MGD (2000
GPM)
2 each @ 4.32 MGD (3000
GPM)
Total Pumping Capacity =
14.42 MGD
1 each @ 6.19 MGD
2 each @ 3.17 MGD (2200
GPM)
2 each @ 4.32 MGD (3000
GPM)
Total Pumping Capacity =
14.98 MGD
Proposed
1.0 MGD Additional Flow
6.5 MGD
9.75 MGD
13.0 MGD
14.45 MGD
271
169
21
2 each @ 2.89 MGD (2000
GPM)
2 each @ 4.32 MGD (3000
GPM)
Total Pumping Capacity =
14.42 MGD
1 each @ 6.19 MGD
2 each @ 4.32 MGD (2200
GPM)
2 each @ 4.32 MGD (3000
GPM)
Total Pumping Capacity =
17.28 MGD

Table 3: (cont.)
Screw Pump
Preliminary Treatment
• Parshall Flume Max.
Hydraulic Loading w/
18" throat
Primary Clarifiers
• Units
• Flow (Inf. + W.A.S)
• Diameter
• S.W.D.
• Depth
• Detention
• Surface Rate
Roughing Filters
• Units
• Diameter
• Depth
• Total Surface Area
• Hydraulic Loading
• Biological Loading
• Recirculation Rate
1 each @ 6.19 MGD (4300 1 each @ 6.19 MGD (4300
GPM)
15.9 MGD
2 ea.
6.70 MGD
75'-0"
8'-3"
11' —1 "
2 hrs. 36 min. @ Avg. Day
800 GPD/SF
2 ea.
100'-0"
5'-11"
15,708 SF (.36 Ac)
30.6 MGD/Acre
5708 Lbs BOD/Acre/Day
0.13 lbs. BOD/SF/Day
100%
GPM)
14.45 MG
7.8 MGD
2 hrs. 14 min. Q Avg. Day
882 GPD / SF
33.3 MGD/Acre
6780 Lbs BOD/Acre/Day
0.16 lbs. BOD/SF /Day
100%
Source: Lexington Regional WWTP Process Control Monthly Reports

Table 3: (cont.)
Aeration Tanks
• Units 6 ea.
• Length x Width 28" x 218' 8"
• S.W.D 14'
• Volume 514,312 C.F.
3.847 M.G.
• R.A.S. Rate 0 to 3.02 MGD 0 to 6.5 MGD
Detention Time (Loading) 5.42 hrs. — 8.4 hrs. 3.6 hrs. — 7.7 hrs.
Aeration Requirements
Carbonaceous 5,729 CFM 6488 CFM
Nitrification 5,257 CFM 5942 CFM
Total 10,986 CFM 12,430 CFM
Final Clarification
• Units 2 ea.
• Diameter 110' 0"
• S.W.D 14'0"
• Surface Area 19,000 SF
• Volume 1.99 M.G.
• R.A.S. Rate 0 — 100% 0 —100%
• Detention Time 8.7 hrs. — 5.62 hrs. 7.3 hrs. — 3.67 hrs.
• Surface Loading Rate 290 GPD/SF 342 GPD/SF

Table 3: (cont.)
Stabilization Pond
• Units 2 ea.
• Volume 5.5 MG
• Detention Time 24.0 hrs.
Chlorine Contact
• Units 2 each
• Length x Width 24'0" x 66'0"
• SWD 5' 43/4"
• Volume 17,094 C.F.
127,860 gallons
20.3 hrs.
• Detention Time
33 Minutes
28 Minutes

CONCLUSIONS
The WWTP was originally designed for an initial average daily flow of 5.5 MGD and an
ultimate maximum hydraulic capacity of 36.7 MGD.
It was anticipated that the plant would be expanded in two stages with each stage adding an
additional 5.5 MGD to average daily flow for an ultimate average daily flow capacity of 16.5
MGD.
The initial design capacity of manholes and interconnecting piping included capacity of the
ultimate maximum hydraulic flow. Unit process structures were designed to be expanded
and/or to be duplicated to provide additional capacity for the ultimate flows. Therefore, the
existing facilities have the hydraulic capacity to handle proposed additional average flow of 1.0
MGD with only minor modifications.

NUTRIENT REMOVAL
Process Modifications - 6.5 MGD Upgrade
Based on our recent discussions regarding the speculative effluent limits pending for
Lexington's existing WWTP, several upgrades to the plant are required. The primary effluent
limitation requiring the upgrades is total phosphorus (TP). Although total nitrogen (TN) limits
were not imposed by the State at this time, the Biological Nutrient Removal (BNR) upgrades
integrate TN removal based on cost effectiveness and future permit inclusion bases. The
following nutrient removal upgrades reflect the proposed 1.0 MGD hydraulic capacity increase
of the WWTP (proposed upgrades reflect revised capacity of 6.5 MGD).
The primary unit processes required by the nutrient removal upgrade include the following:
• BNR Upgrades:
BNR process includes partitioning the existing six aeration basins into multiple
chambers to provide three stages of biological conditions for TP uptake and
removal and TN conversion. The three stages include Anaerobic, Anoxic and
Oxic (or Aerated) zones. Based on preliminary sizing, the existing aeration
basins should provide adequate volume for these three stages at the design flow
rate of 6.5 MGD. Consideration was given to modify the existing roughing filters
to be used as first stage anaerobic selector tanks prior to the aeration basins. This
option will be pursued if additional capacity is determined to be needed. In the
current design, the roughing filters would be bypassed and abandoned.
• Biosolids Dewatering:
The BNR process produces additional solids wasting volume. In addition, if
chemical trimming is utilized to enhance TP removal, this chemical precipitation
step will further increase waste activated sludge volume. Therefore, a solids
dewatering unit is proposed to reduce the biosolids volume to the existing
anaerobic digesters. A dissolved air flotation (DAF) unit is proposed for this
function.
• Solids Contact Reactor:
As a byproduct of the BNR process, the digester supernatant will contain high
concentrations of phosphorus. Chemical precipitation can be utilized to reduce
the sidestream supernatant to acceptable levels prior to return to the primary
influent.
• Chemical Feed System:
As a backup to the BNR process, a chemical feed system (typically alum) is
included in the design to chemically precipitate total phosphorus below the
permit limit of 0.5 mg/L. The precipitated solids are then removed in the
existing final clarifiers.

An estimate of probable cost for the 6.5 MGD upgrade is attached. The estimate for probable
total project cost, which includes construction, contingencies, and technical fees, is
approximately $5,431,375.00.

Table 4: Lexington Regional Wastewater Treatment Plant Hydraulic Analysis
Estimate of Probable Project Cost
PROCESS MODIFICATIONS - 6.5 MGD Upgrade
2002 Cost Estimate
!c NR Process:
1+ quipment
322,500
1 ectrical
171,600
,1 odifications to Existing Tank
412,000
and Piping
200,000
Subtotal =
$1,106,100.00
IP AF Facility;
+ • uipment
$172,000.00
r • uipment Installation
152,800.00
'-tructural Grading
81,800.00
oncrete
uilding:
161,000.00'
Pump
96,000.00
1 Compressor
134,000.00
' cellaneous Metals
j iping.
23,000.00
Internal
34,300.00
Yard
28,600.00
ectrical
51,500.00
Subtotal =
olids Contact Reactor.
$935,000.00
+ • uipment
$114,500.00
1 tallation
99,500.00
+ oncrete
42,300.00
,ia ectrical
23,000.00
' arct Piping
30,000.00
r ump Station
75,000.00
Subtotal =
hemical Feed System;
$384,300.00
$4,500.00
tcuctural Grading
oncrete
17,000.00
1 . 'pment (feed pumps, tanks, etc.)
96,000.00
i quipment Installation
75,500.00'
1 iping:
Yard
21,400.00
1 Internal
12,000.00
ectrical
55,000.00
Subtotal =
i!' •.i 0 •a•
$281,400.00
$228,800.00
' ellaneous Piping
alves
309,000.00
ates
63,000.00
• DA/Instrumentation
630,000.00
+ echanical Bar Screen
114,500.00
- tatic Aerator
293,000.00
Subtotal =
$1,638,300.00
otal Construction Cost - 6.5 MGD Upgrade
$4,345,100.00
0% Contingency
434,510.00
15% Technical
651,765.00
otal Estimate Cost - 6.5 MGD Upgrade
•
$5,431,375.00

Table 4: Lexington Regional Wastewater Treatment Plant Hydraulic Analysis
Estimate of Probable Project Cost
PROCESS MODIFICATIONS - 6.5 MGD Upgrade
2002 Cost Estimate
BNR Process:
Equipment
322,500
Electrical
171,600
Modifications to Existing Tank
412,000
Yard Piping
200,000
Subtotal =
$1,106,100.00
DAF Facility;
Equipment
$172,000.00
Equipment Installation
152,800.00
Structural Grading
81,800.00
Concrete
161,000.00
Building:
Pump
96,000.00
Compressor
134,000.00
Miscellaneous Metals
23,000.00
Piping:
Internal
34,300.00
Yard
28,600.00
Electrical
51,500.00
Subtotal =
$935,000.00
Solids Contact Reactor:
Equipment
$114,500.00
Installation
99,500.00
Concrete
42,300.00
Electrical
23,000.00
Yard Piping
30,000.00
Pump Station
75,000.0
Subtotal =
$384,300.0
Chemical Feed System:
Structural Grading
$4,500.0
Concrete
17,000.00
Equipment (feed pumps, tanks, etc.)
96,000.
Equipment Installation
75,500.
Piping:
Yard
21,400.
Internal
12,000.01
Electrical
55,000.01
Subtotal =
$281,400.01
Division 20 Items:
Miscellaneous Piping
$228,800.00
Valves
309,000.0I
Gates
63,000.0I
SCADA/Instrumentation
630,000.0
Mechanical Bar Screen
114,500.01
Static Aerator
293,000.0'
Subtotal =
$1,638,300.00.
Total Construction Cost - 6.5 MGD Upgrade
$4,345,100.00.
10% Contingency
434,510.01
15% Technical
651,765.00.
!Total Estimate Cost - 6.5 MGD Upgrade
$5,431,375.01

Process Modifications - 8.25 MGD Upgrade
Information was also requested regarding a plant expansion to 8.25 MGD. The same BNR
process components outlined in the 6.5 MGD upgrade would be utilized in the expansion. It
should also be noted that the upgrade and expansion could be constructed separately or
simultaneously. To accommodate the increased capacity, four primary processes would have to
modified and/or expanded.
• Add BNR Train
• Main Lift Station Upgrade
• New Final Clarifier
• New Digester
An estimate for probable cost for the 8.25 MGD expansion is attached. The estimate of probable
total project cost, including the cost of the 6.5 MGD upgrade, for construction, contingencies,
and technical fees is approximately $10,226,250.00.

Table 5: Lexington Regional Wastewater Treatment Plant Hydraulic Analysis
Estimate of Probable Project Cost
PROCESS MODIFICATIONS - 8.25 MGD Expansion
2002 Cost Estimat,
Cost of 6.5 MGD Upgrade
$4,345,100.0'
BNR - Add New Trait.:•
Structural Grading
$231,700.01
Concrete
944,000.0 1'
Equipment
370,000.0 1+
,Electrical
212,000.0 P+
Yard Piping
372,000.011
Subtotal =
$2,129,700.00
Main Lift Station Upgrade:
Structural Grading
$231,700.0 1
Concrete
944,000.011
Equipment
370,000.01
Electrical
212,000.0 1 ,
Yard Piping
372,000.01
Subtotal =
$2,129,700.0 is
New Final Clarifier:
Structural Grading
$243,000.001
1
Concrete
538,000.01
Equipment
131,600.01
Electrical
57,200.1
Yard Piping
57,500.11
Subtotal =
$1,027,300.0I
New Digester,
$44,000.01
Structural
Concrete
422,500.01
Equipment
450,800.01
Electrical
114,500.01
Gas Storage
303,000.01.
Subtotal =
$1,334,800.0"
Pivision 20 Items:
Miscellaneous Piping
$150,000.0 t
Valves
309,000.01
Gates
63,000.11
SCADA/Instrumentation
630,000.011
Mechanical Bar Screen
114,500.01
Static Aerator
293,000.01
Subtotal =
$1,559,500.0
Total Construction Cost - 8.25 MGD Expansion
$8,181,000.0
10% Contingency
818,100.01
15% Technical
1,227,150.01
Total Estimate Cost - 8.25 MGD Expansion
$10,226,250.0 1

Alternate Process Modifications
Several other unit process upgrades, including Denitrification, Chlorination/Dechlorination,
and Grit Removal, are also presented for discussion. Both Denitrification and
Chlorination/Dechlorination are not required due to imposed speculative limits, they should be
considered to further enhance the treatment capability of the WWTP to meet future NPDES
limits.

Table 6: Lexington Regional Wastewater Treatment Plant Hydraulic Analysis
Estimate of Probable Project Cost
Additional Unit Processes to Consider
2002 Cost Estimate
Denitrification:
Structural Grading
$30,900.01
Concrete
515,000.01
Miscellaneous Metals
126,000.01
Equipment
Blower
231,100.01
Diffusers
112,000.01
Installation
286,000.01
Electrical
160,200.0 i
Yard Piping
263,000.0.
Subtotal =
$1,724,200.011
10% Contingency
172,420.011
15% Technical
258,630.011
Total Estimate of Project Cost
$2,155,250.0 t,
Chlorination/Dechlorination:
Structural Grading
$45,200.01'
Concrete
110,000.0 11
Masonry
18,000.011
Miscellaneous Metals
30,500.01
Roofing
29,000.01
Painting
15,700.011
Hoist
16,400.11
Piping
30,000.011
Chlor/Dechlor Equipment
98,200.11
Fan and Aerator
18,300.01'
Electrical
45,800.01
Yard Piping
28,600.01
Subtotal =
$485,700.0 0i
10% Contingency
48,570.1 1'
15% Technical
72,855.011
Total Estimate of Project Cost
$607,125.0 t
Grit Removal=
Structural Grading
58,000.11
Concrete
155,200.0 1!
Equipment
120,100.011
Electrical
63,000.1 1i
Subtotal =
$346,300.0
10% Contingency
34,630.011
15% Technical
51,945.011
Total Estimate of Project Cost
$432,875.0
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