Clinton Street CSO Abatement Project Facility Plan (Nov 2005)
by Environmental Engineering Associates, LLP
for Onondaga County Department of Water Environment Protection

6. Optimization of recommended/preferred CSO abatement plan

6.1 Introduction

With the selection of the recommended/preferred CSO abatement plan described in Section 5.7, i.e., in-line storage/vortex separator RTF at Clinton Station site, several additional abatement plan analyses were undertaken to assess various conditions to optimize the plan for implementation. This section describes and presents the results of these optimization analyses.

6.2 CSO 037 assessment

The purpose of this assessment was to evaluate the cost-effectiveness of including the CSO from CSO drainage basin 037 (East Adams Street) into the Clinton Street CSO RTF, in lieu of separating the existing combined sewers within the CSO 037 drainage basin, as currently directed by the ACJ. This assessment was considered appropriate due to the short distance between the CSO 037 outfall and the proposed Clinton Street CSO RTF, along with the anticipated complexity and potential construction risks, difficulties, and impacts to local business operations associated with separation of combined sewers within the highly urbanized CSO 037 drainage basin.
 

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Figure 6-1 depicts the CSO drainage basin within the downtown Syracuse area and the multiple businesses that reside within this congested City area.

As described in Sections 1 through 5, the following Clinton Street CSOs will be diverted and conveyed to the Clinton Street RTF at the Clinton Station site: 027, 028, 029, 030, 031, 032, 033, 034, 035, and 036 (10 CSOs total). Per the ACJ, CSO drainage basin 037 is planned for full sewer separation of existing combined sewers into separate sanitary and storm sewer systems to abate the overflow from CSO 037.

As described in Section 5.4, the total estimated peak flow (1-year, 2-hour, 15-minute rainfall interval storm event) from the 10 current Clinton Street CSOs to the Clinton Street vortex separator RTF is 755 cubic feet per second (cfs) (based on a full service area RTF at the Clinton Station site). The estimated peak flow rate from CSO 037 for the same design storm condition is 22 cfs. Based on sewer system modeling data provided by modeling consultant Brown and Caldwell, diversion of CSO 037 overflow to the Clinton Street CSO RTF will increase the peak flow to the Clinton Street RTF to 775 cfs (2.6% increase) (Note: flow attenuation in the conveyance system reduces the CSO 037 peak flow rate discharging to the Clinton Street RTF such that the 22 cfs is not directly additive to the 755 cfs for the original 10 CSOs).

Using the estimated construction cost for CSO Abatement Alternative 1d - RTF (Vortex Separator) - No Sewer Separation at the Clinton Station site (as presented in Table 5-9) as the basis for comparison, estimated construction, project, annual O&M and present worth costs were developed for the following two approaches.
 

Table 6-1 presents the estimated construction and project costs for the two approaches to abating CSO 037 as described above.
 

TABLE 6-1. CSO 037 ASSESSMENT CONSTRUCTION AND PROJECT COST COMPARISON ($000,000)
Component	Approach 1	Approach 2
Clinton RTF and conveyances
Construction costs (nearest $100,000)
RTF	(1) $33.0	$33.9
Conveyances	(1) 19.0	(1) 19.0
Subtotal	52.0	52.9
CSO 037
Construction costs (nearest $100,000)
Sewer separation (6,135 lf x 762/lf (3)	(2) 5.0	0
Additional conveyances	0	1.3
Subtotal	5.0	1.3
Est construction cost	57.0	54.2
Est site mitigation /special costs of site (4)	6.3	6.3
Subtotal	63.3	60.5
Project related costs (5)	14.3	13.6
Total estimated project cost	$77.6	$74.1

Notes:
(1) Source: Table 5-9
(2) Based upon sewer separation costs presented in Section 5.6 and drainage basin sewer lengths derived from sewer maps prepared by City of Syracuse Department of Planning, 1965 and US Army Corps of Engineers - Buffalo District, Design of Sewer Separation Combined Sanitary/Storm Sewers, Onondaga County, Syracuse, New York, prepared by O'Brien & Gere Engineers, Inc.
(3) Based on $693/LF plus a 10% contingency (source: Appendix I).
(4) From Table 5-11.
(5) Project Related Costs includes engineering, legal and administrative costs estimated to equal 25% of the Estimated Construction Cost.

A present worth comparison, including estimated annual O&M costs, of the two approaches is presented in Table 6-2.
 

TABLE 6-2. CSO 037 ASSESSMENT, PRESENT WORTH ANALYSIS ($000,000)
Abatement approach	Total est proj cost (1)	Est annual O&M	Present worth (2)
Approach 1	$77.6	$1.028	$92.3
Approach 2	74.1	1.058	89.0
Note: (1) Based on Feb 2005 dollars (ENRCCI = 7298), rounded. (2) Present Worth Cost based on a 25-year useful life and a discount rate equal to 5.0%

Based on the present worth cost comparison presented in Table 6-2, it is more cost-effective to collect and convey CSO 037 overflows to the Clinton Street RTF at the Clinton Station site than to provide sewer separation within the CSO 037 drainage basin. It is recommended that Approach 2 contained within Table 6-2 be implemented to further optimize the Clinton CSO abatement plan.

Table 6-3 presents a summary listing of the CSO outfalls recommended to be included in the Clinton Street CSO abatement plan, including CSO 037.
 

TABLE 6-3. CSO OUTFALL ONE-YEAR PEAK FLOW RATES
CSO	Basin Area, Acres	Peak Flow Rate(1), cfs
027	134	86
028	24	9
029	8	12
030	312	216
031	25	14
032	25	16
033	18	16
034	214	264
035	23	16
036	188	135
037	33	22
Note: (1) Peak flow rate based upon 1-year frequency, 2-hour duration, 15-minute rainfall interval storm event with free-outlet design condition. cfs = cubic feet per second

Figure 6-3 depicts each of the CSO outfalls within the Clinton Street CSO service area.

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Figure 6-2 depicts each of the CSO outfalls in the Clinton Street CSO service area.

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Figure 6-3 depicts preliminary conveyances and in-line storage/vortex separator RTF at Clinton site (CSO 037
inc)

6.3 Off-line upstream storage evaluation

Due to potential concerns regarding the volume and frequency of treated CSO discharges associated with the full service area in-line storage/vortex separator RTF at the Clinton Station site, an evaluation was conducted to assess the implementation of a smaller (half-size) vortex separator RTF in combination with additional upstream storage to reduce the vortex separator peak flow rate and the number of influent flow pumps and vortex separator units required. To conduct this evaluation, EEA coordinated with the modeling consultant Brown and Caldwell to execute the previously calibrated SWMM EXTRAN model for the Clinton Street CSO service area to determine the upstream storage volume required to reduce the peak RTF influent flow rate from 755 cfs to 378 cfs. (Note: This optimization evaluation was conducted independent from the CSO 037 assessment [Section 6.2] and, therefore, is based on a peak RTF influent flow rate of 755 cfs.}

The results of Brown and Caldwell's modeling analysis revealed that a 3.5 MG upstream storage facility would be required to reduce the peak RTF influent flow rate to 378 cfs while maintaining compliance with ACJ treatment requirements.
 

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Figure 6-4 is a preliminary layout of reduced-size vortex separator RTF and 3.5 MG upstream storage at Clinton
site.
 

 

A summary of the principal advantages and disadvantages of the reduced size vortex separator RTF and upstream storage is presented in Table 6-4.
 

TABLE 6-4. UPSTREAM STORAGE/REDUCED SIZE VORTEX SEPARATOR

Advantages   Higher degree of settleable solids, TSS, BOD, TKN, P and floatables removal in comparison to full service area vortex separator   Provides capture and treatment of storm water pollutants as well as sanitary wastewater pollutants   Provides sufficient treatment for downstream disinfection   Disruption due to construction is confined to a smaller area in comparison to sewer separation   Existing sanitary connections and storm leaders within buildings in the urban area are undisturbed   Smaller above grade facilities will result in less visual impact in comparison to full service area vortex separator facility   Conveys a larger volume of CSO to Metro for treatment in comparison to a full service area vortex separator facility   Has lower annual O&M costs in comparison to full service area vortex separator

Disadvantages   Requires approximately 23% additional land area requirements in comparison to full service area vortex separator facility   Larger consolidation pipelines required for regional storage facilities will require deeper and wider excavation areas in comparison to sewer separation   Requires larger capacity pumps to dewater the facility in the same amount of time as the full service area vortex separator facility   May not allow permanent closure of CSOs   Has higher total project cost, construction cost and net present worth cost in comparison to full service area vortex separator   Requires greater need for ground water pumping and risk of settlement due to more extensive deep excavation in comparison to full service area vortex separator   Above grade facilities will have more visual impact in comparison to regional storage facility.

For comparison purposes, modeling consultant Brown and Caldwell was requested to estimate the average annual number of treated (and disinfected) CSO discharges from a full service area in-line storage/vortex separator RTF (755 cfs) (the previously identified recommended/preferred CSO abatement approach per Section 5.7) versus the number of treated (and disinfected) CSO discharges from a 3.5 MG upstream storage/378 cfs vortex separator RTF, as described above. Based on Brown and Caldwell's modeling results, the number of treated (and disinfected) CSO discharges would be as follows:
 

Average annual treated/disinfected CSO discharges
CSO abatement approach	#	Volume
1) Full service area in-line storage/vortex separator RTF (755 cfs)	18	118 MG
2) 3.5 MG upstream storage/378 cfs vortex separation RTF	9	70 MG
MG = million gallons

Table 6-5 presents the estimated construction and project costs for the two approaches to abating CSOs in the Clinton Street CSO drainage basins as described above.

Table 6-5. Off-line upstream storage evaluation construction and project cost comparison
Component	Approach 1 (1)	Approach 2 (2)
Clinton Street RTF/Conveyances
Construction costs (nearest $100,000)
Conveyances	$19,000,000	$19,000,000
Vortex separator	33,000,000	26,600,000
Storage tank	0	18,900,000
Subtotal	$52,000,000	$64,500,000
Estimated construction cost	$52,000,000	$64,500,000
Estimated site mitigation costs (3)	4,400,000	4,400,000
Estimated special costs associated with site (4)	1,900,000	1,900,000
Subtotal	58,300,000	70,800,000
Project related costs	13,000,000	16,100,000
Total estimated project cost	$71,300,000	$86,900,000

Tables 6-6 and 6-7 present detailed construction cost breakdowns for Approaches 1 and 2, respectively.

Table 6-6. Detailed Construction Cost Breakdown for Approach 1 (In-Line Storage / Vortex Separator [755 cfs] at Clinton Station Site)
A. Conveyances	Estimated cost
1. Mobilization / Demobilization	$460,000
2. Site Preparation	$210,000
3. Excavation	$585,000
4. Sheeting and Bracing	$7,680,000
5. Dewatering	$1,040,000
6. Furnish and Install 24-Inch PVC	$45,000
7. Furnish and Install 27-Inch PVC	$30,000
8. Furnish and Install 36-Inch PVC	$195,000
9. Furnish and Install 42-Inch PVC	$90,000
10. Furnish and Install 48-Inch PVC	$85,000
11. Furnish and Install 60-Inch PCCP	$205,000
12. Furnish and Install 66-Inch PCCP	$45,000
13. Furnish and Install 72-Inch PCCP	$80,000
14. Furnish and Install 84-Inch PCCP	$680,000
15. Furnish and Install 96-Inch PCCP	$1,065,000
16. Furnish and Install 108-Inch PCCP	$155,000
17. Furnish and Install 120-Inch PCCP Outfall	$100,000
18. Furnish and Install 16-Inch DIP Force Main	$220,000
19. Pipe Bedding	$120,000
20. Special Backfill	$370,000
21. Pavement Restoration	$215,000
22. Rock Removal	$5,000
23. Regular Manholes	$30,000
24. Special Manholes	$1,180,000
25. Creek Crossing (72-Inch)	$110,000
26. Creek Crossing (36-Inch)	$85,000
27. Railroad Boring	$135,000
28. Traffic Maintenance	$80,000
29. Utilities Relocation	$520,000
Subtotal Conveyances	$15,820,000
Construction Contingency (20%)	$3,165,000
Total Estimated Conveyances	$18,985,000
Rounded To	$19,000,000
B. Vortex Separator (755 cfs) Regional Treatment Facility
1. Mobilization / Demobilization	$780,000
2. Vortex Separator Facility
a. Site Work	$3,620,000
b. Structural Concrete	$3,875,000
c. Structural Miscellaneous Metals	$390,000
d. Overhead Crane	$30,000
e. Structural Roof	$515,000
f. Architectural	$2,560,000
g. Mechanical Equipment	$3,300,000
Subtotal	$14,290,000
3. Disinfection Tank
a. Site Work	$2,080,000
b. Structural Concrete	$2,960,000
c. Structural Miscellaneous Metals	$75,000
d. Structural Roof	$260,000
e. Mechanical Equipment	$895,000
Subtotal	$6,270,000
4. Piping	$1,060,000
5. Heating, Ventilation, and Odor Control	$1,515,000
6. Electrical and Instrumentation	$2,160,000
7. Plumbing	$650,000
8. Geotechnical	$810,000
Subtotal Vortex Separator RTF	$27,535,000
Construction Contingency (20%)	$5,505,000
Total Estimated Vortex Separator RTF	$33,040,000
Rounded To	$33,000,000
C. Total Estimated Construction Cost (Items A and B)	$52,000,000
Note: 1. Costs Based on February 2005 Dollars (ENRCCI = 7298)

A present worth comparison, including estimated annual O&M costs, of the two approaches is presented in Table 6-8.
 

TABLE 6-8. OFF-LINE UPSTREAM STORAGE EVALUATION PRESENT WORTH ANALYSIS
Abatement Approach	Total est. project cost (1)	Est. annual O&M cost	Present worth cost (2)
Approach 1: Vortex Separator RTF (peak flow of 755 cfs) at Clinton Station site, no sewer separation within current Clinton Street CSO drainage basins.	$71,300,000	$1,026,000	$85,900,000
Approach 2: Vortex Separator RTF (peak flow of 378 cfs) and off-line upstream storage (3.5 MG) at Clinton Station site, no sewer separation within current Clinton Street CSO drainage basins.	$86,900,000	$766,000	$97,800,000
Note: (1) Based on February 2005 Dollars (ENRCCI = 7298), rounded. (2) Present Worth Cost Based on a 25-year useful life and a discount rate equal to 5.0%

As presented in Table 6-8, a full service area in-line storage/vortex separator RTF (755 cfs) at the Clinton Station site (Alternative 1d) has a lower estimated present worth ($85,900,000) than the estimated present worth ($97,800,000) of the 3.5 MG upstream storage/378 cfs vortex separator RTF approach. Therefore, the in-line storage/full service area vortex separator RTF (755 cfs) at the Clinton Station site remains the most cost-effective CSO abatement plan for the Clinton Street CSO service area.

6.4 CSO closure evaluation

Recognizing that one of the objectives of the ACJ is to provide the most beneficial CSO abatement program for the Clinton Street CSO service area from a receiving water quality standpoint, a supplemental optimization analysis was conducted to assess the impact of physically sealing the existing CSOs in the service area for the recommended/preferred CSO abatement approach (i.e., in-line storage/vortex separator RTF at Clinton Station site, including CSO 037). This would involve permanently sealing the existing CSOs by installing an upstream bulkhead on the overflow pipe to Onondaga Creek using brick and block methods. Bulkheading of the overflow would generally occur at the regulator structure, if possible. To conduct this analysis, EEA, in conjunction with modeling consultant Brown and Caldwell, identified the increased conveyance sizing and vortex separator sizing that would be required upon closure of the various CSOs within the service area.

For the purpose of this optimization analysis, closure of the service area CSOs was evaluated beginning with the outfall contributing the smallest flow proceeding sequentially to the outfall contributing the largest flow. A summary matrix presenting the results of the sequential CSO closure analysis is presented in Table 6-9.
 

TABLE 6-9. CSO CLOSURE EVALUATION
Assoc convey- ance pipeline	Dia (ft)*	Lngth (ft)	028	029	031	032	033	035	037	027	036	030	034
W Jefferson	3.5	280	3.5	3.5	3.5	3.5	3.5	3.5	3.5	*4.5	4.5	4.5	4.5
W Jefferson	4	315	4	4	4	4	4	4	4	*5	5	5	5
W Jefferson	7	635	7	7	7	7	7	7	7	*7.5	7.5	*8	8
West St.	2	415	*2.5	2.5	2.5	2.5	2.5	2.5	2.5	2.5	2.5	2.5	2.5
West St.	3	685	3	3	*3.5	3.5	3.5	3.5	3.5	3.5	3.5	3.5	3.5
West St.	3	80	3	3	*3.5	3.5	3.5	3.5	3.5	3.5	3.5	3.5	3.5
West St.	3	185	3	3	3	*3.5	3.5	3.5	3.5	3.5	3.5	3.5	3.5
West St.	3	80	3	3	3	*3.5	3.5	3.5	3.5	3.5	3.5	3.5	3.5
RTF Influent	9	120	9	9	9	9	9	9	9	9	9	9	9
W Onondaga	5	280	5	5	5	5	5	5	5	5	5	5	5
W Onondaga	5.5	50	5.5	5.5	5.5	5.5	5.5	5.5	5.5	5.5	5.5	5.5	5.5
W Onondaga	2.25	235	2.25	2.25	2.25	2.25	*3.00	3.00	3.00	3.00	3.00	3.00	3.00
W Onondaga	6	95	6	6	6	6	6	6	6	6	6	6	6
W Onondaga	3	580	3	3	3	3	3	3	3	3	3	3	3
W Onondaga	7	70	7	7	7	7	7	7	7	7	7	7	*8
W Onondaga	8	900	8	8	8	8	8	8	8	8	9	9	*9.5
Clinton RTF influent (cfs)	775		775	775	800	800	825	850	850	925	1,050	1,175	1,300

Notes:
* Based on 1-yr design storm
1. Values with asterisk signify changes to pipe diameters/RTF influent flow due to CSO closing.
2. CSO closings occurred sequentially beginning with CSO 028, as shown in this table (for example, closure of CSO 031 also includes closure of CSOs 028 and 029).
3. Results are based on the model response to the 5-year design storm, as conducted by modeling consultant Brown and Caldwell.
4. Results include incorporating CSO 037 into the full service area in-line storage/vortex separator RTF, as determined to be cost-effective pursuant to Section 6.2.

A capital construction cost, project cost, O&M cost, and 25-year present worth cost comparison of the sequential CSO closures was then prepared to provide these data for County consideration of potential permanent CSO closures as part of the overall Clinton Street CSO abatement plan. Table 6-10 presents the total estimated construction and project costs for the sequential closure of CSOs within the Clinton Street CSO service area as described in Table 6-9.
 

TABLE 6-10. CSO CLOSURE EVALUATION, EST. PROJECT COSTS ($000,000)
CSO to be closed (1)	RTF	Convey- ances	Est const cost	Est site mitigation (3)	Subtotal	Proj related costs (4)	Total
None (2)	$33.89	$20.31	$54.20	$6.30	$60.50	$13.55	$74.05
CSO 028	33.89	20.33	54.22	6.30	60.52	13.56	74.08
CSO 029	33.89	20.33	54.22	6.30	60.52	13.56	74.08
CSO 031	34.98	20.36	55.34	6.30	61.64	13.84	75.48
CSO 032	34.98	20.37	55.35	6.30	61.65	13.84	75.49
CSO 033	36.07	20.39	56.46	6.30	62.76	14.12	76.88
CSO 035	37.17	20.39	57.56	6.30	63.86	14.39	78.25
CSO 037	37.17	20.39	57.56	6.30	63.86	14.39	78.25
CSO 027	40.45	20.86	61.31	6.30	67.61	15.33	82.94
CSO 036	45.91	21.18	67.09	6.30	73.39	16.77	90.16
CSO 030	51.38	21.19	72.57	6.30	78.87	18.14	97.01
CSO 034	56.84	21.29	78.13	6.30	84.43	19.53	103.96

Notes:
(1) CSO closings occur sequentially beginning with CSO 028.
(2) From Table 6-1 (rounded to nearest $10,000 vs. nearest $100,000).
(3) From Table 5-11.
(4) Project Related Costs includes engineering, legal, and administrative costs estimated to equal 25% of the estimated construction cost.

Table 6-11 presents the 25-year present worth cost comparisons, including estimated annual O&M costs, for these same required CSO closures.
 

TABLE 6-11. CSO CLOSURE EVALUATION, PRESENT WORTH ANALYSIS
CSOs to be closed	Total est const cost (1)	Est annual O&M	Present worth (2)
No closures	$74,050,000	$1,058,000	89,150,000
CSO 028	74,080,000	1,058,000	89,180,000
CSO 029	74,080,000	1,058,000	89,180,000
CSO 031	75,480,000	1,092,000	91,060,000
CSO 032	75,490,000	1,092,000	91,070,000
CSO 033	76,880,000	1,126,000	92,950,000
CSO 035	78,250,000	1,160,000	94,800,000
CSO 037	78,250,000	1,160,000	94,800,000
CSO 027	82,940,000	1,263,000	100,990,000
CSO 036	90,160,000	1,433,000	110,660,000
CSO 030	97,010,000	1,604,000	119,990,000
CSO 034	103,960,000	1,775,000	129,220,000
Note: (1) Based on Feb 2005 dollars (ENRCCI = 7298), rounded to nearest $10,000, from Table 6-6. (2) Present Worth Cost based on a 25-year useful life and a discount rate equal to 5.0%

Based upon the present worth cost comparison presented on Table 6-11, for a minimal additional present worth cost of $30,000, it appears feasible to close CSOs 028 and 029 as part of the Clinton CSO abatement plan. These CSOs are also both located in the downtown Armory Square area and would provide the additional benefit of CSO closure in close proximity to the future planned Onondaga Creekwalk within the Armory Square area.

6.5 Recommended plan

As presented in Section 5.7, the recommended/preferred CSO abatement approach for the Clinton Street CSO service area is a full service area in-line storage/ vortex separator RTF at the Clinton Station site.

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Table 6-12 summarizes optimization alternatives for the recommended/preferred CSO abatement approaches.
These approaches were presented in Sections 6.2, 6.3, and 6.4.

The results of the optimization analyses indicate the following.

• Collecting and conveying CSO 037 overflows to the Clinton Street CSO in-line storage/vortex separator RTF at the Clinton Station site is more cost-effective to implement than to provide sewer separation for the CSO 037 drainage basin, as is currently directed by the ACJ.
• Off-line upstream storage and a reduced (half-size) vortex separator RTF at the Clinton Station site is not more cost-effective than a full service area in-line storage/vortex separator RTF at the Clinton Station site.
• Closure of CSOs 028 and 029, for a minimal additional present worth cost of $30,000, appears justifiable as part of the CSO abatement plan for the Clinton Street CSO service area.

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A preliminary plan layout of the recommended plan is presented in Figure 6-5.

 

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Figure 6-6 depicts the recommended plan on an aerial photo of the project area.

 

Based upon the above, the recommended CSO abatement plan for the Clinton Street CSO service area is as follows:

• Construction of a full service area (including CSO 037) in-line storage/vortex separator RTF, with a peak influent flow rate of 775 cfs, at the Clinton Station site.
• Closure (physically sealing) of CSOs 028 and 029 in the Armory Square area.

The total estimated project cost and estimated annual O&M cost for the recommended plan is presented below:
 

Estimated construction cost	$54,220,000
Estimated site mitigation/special costs associated with site	6,300,000
Subtotal	60,520,000
Project-related costs	13,560,000
Total estimated project cost	74,080,000
Total estimated annual O&M cost	1,058,000

6.6 Preliminary basis of design

A preliminary basis of design for the recommended plan is presented in Table 6-13.
 

TABLE 6-13. PRELIMINARY BASIS OF DESIGN
I. CONVEYANCES
A. West Jefferson Street CSO Transmission Pipeline
CSOs	027, 029 (to be closed), 030
Pipe Type	Pre-stressed concrete cylinder pipe (PCCP)
Diameter, inches	84
Pipe Type	Polyvinyl chloride (PVC)
Diameter, inches	48, 42
B. West Street CSO Transmission Pipeline
CSOs	028 (to be closed), 031, 032
Pipe Type	PVC pipe
Diameter, inches	36, 30
C. West Onondaga Street CSO Transmission Pipeline
CSOs	033, 034, 035, 036, 037
Pipe	Type PCCP
Diameter, inches	108, 96, 84, 72, 66, 60
Pipe Type	PVC
Diameter, inches	36, 27
II. REGIONAL TREATMENT FACILITY
A. Design Flow Rate
Storm frequency, year	1
Storm duration, hour	2
Rainfall interval, minutes	15
Peak influent design flow rate, cubic feet per second (cfs)	775
B. Trash Rack
Type	Manual
Location	Influent stilling well
Clear opening, inches	4
Number of units	2 (one vertical, one inclined at 60 degs.)
Materials of construction	Aluminum or stainless steel
C. Grit/Debris Removal Facilities
Type	Grit sump
Location	Influent stilling well
Removal mechanism	Clamshell with overhead bridge crane
Disposal	Truck hauler
D. Influent Pumps
Pump type	Mixed or axial flow
Number of units	5 (4 operating, 1 standby)
Capacity per unit, cfs	194
Drive type	Constant speed
E. Vortex Solids Separator Influent Gates
Type	Motor-operated sluice gate
Materials of construction	Fabricated stainless steel
Number	3
F. Vortex Solids Separator
Type	USEPA swirl concentrator
Design settleable solids recovery, percent	90
Number of units	4
Capacity per unit, cfs	194
Materials of construction	Reinforced concrete basin with coated steel internals
Chamber diameter, feet	43
G. Dewatering Pump
Pump type	Submersible, recessed impeller, grit handling
Number of units	3 (2 installed, 1 spare)
Drive type	Variable frequency drive
H. Disinfection Chemical Storage Equipment
1. Chlorination
Chemical	Liquid Sodium Hypochlorite
Design chemical strength, percent	10
Chemical storage	Vertical, cross-linked HDPE tank
2. Dechlorination
Chemical	Liquid Sodium Metabisulfite
Design chemical strength, percent	38