5. Detailed evaluation of most viable CSO abatement approaches, Onondaga Lake Improvement

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

5. Detailed evaluation of most viable CSO abatement approaches

5.1 Introduction

This section presents a detailed evaluation of the four most viable Clinton Street CSO abatement approaches selected for further evaluation. This evaluation includes preliminary basis of design development for the abatement approaches, preliminary cost estimates for the abatement approaches, and identification of the recommended/proposed CSO abatement approach for the Clinton Street CSO service area.

5.2 Sewer separation

As discussed previously, sewer separation as a CSO abatement approach entails the separation of existing combined sewers into separate sanitary sewer and storm sewer systems. Separation normally requires the construction of a new sanitary sewer system parallel to the existing combined sewer system. The combined sewer system is then left in place to serve as a storm sewer and all sanitary connections are switched over to the new sanitary sewer line. However, under some circumstances it may be determined to be more cost-effective or otherwise preferable to convert the combined sewer to a sanitary sewer and to construct a new storm sewer.

In addition to being defined previously as a viable CSO abatement approach for the Clinton Street CSO service area, the County, pursuant to the ACJ, is required to conduct sewer separation evaluations to identify where sewer separation may be a more cost-effective alternative to consolidation of CSO flows for treatment at a Clinton Street RTF. Specifically, the ACJ states:

A cost evaluation of sewer separation projects proposed by the city, or by any party to this agreement and order, shall be implemented by the county. When doing this evaluation, the cost of separation shall be compared with the savings realized from the sum total of: a.) reduced CSO abatement project costs; b.) reduced operating costs at the Metro sewage treatment plant; and any other savings as applicable; and achieves comparable water quality benefits. The County is obligated to construct only those sewer separation projects for which the anticipated savings exceed expected costs." [emphasis added]

To achieve compliance with the ACJ requirements, separation of the entire and/or portions of the Clinton Street CSO service area were evaluated as follows:

A. Sewer separation of the entire Clinton Street CSO service area;

B. Sewer separation of CSO drainage basins west of Onondaga Creek (excluding 036)—028, 031, 032, 033, and 035—with conveyance and storage or treatment of remaining service area CSOs (027, 029, 030, 034, and 036) at a facility to be located at a final selected preferred site; and

C. Sewer separation of CSO drainage basins west of Onondaga Creek and north of Tully Street (excluding 036)—028, 031, and 032—with conveyance and storage or treatment of the remaining service area CSOs (027, 029, 030, 033, 034, 035, and 036) at a facility to be located at a final selected preferred site.

In addition to the above sewer separation evaluations, the County met with City of Syracuse representatives to identify any additional areas within the Clinton Street CSO service area where sewer separation may be considered to be beneficial.

Appendix F includes a copy of the meeting minutes from the meeting with City of Syracuse representatives to discuss other potential sewer separation opportunities in the City. Based on these discussions, the City of Syracuse did not identify any additional areas within the Clinton Street CSO service area where sewer separation may be warranted and/or beneficial. For this reason, the three sewer separation evaluations identified above were determined to exceed the requirements of the ACJ relative to supplemental sewer separation evaluations.

Click here for Appendix F. Meeting minutes, meeting with City of Syracuse representatives concerning sewer separation.

As noted earlier, sewer separation entails separating the existing combined sewers into separate sanitary and storm sewer systems. In highly urbanized areas, like the Clinton Street CSO service area, sewer separation is highly disruptive to both vehicular and pedestrian traffic. This is due to the fact that most existing combined sewers are located below urban streets. The construction of a new sanitary sewer system parallel to the existing combined sewer system below urban streets is further complicated by the multitude of other utilities that are also generally located beneath these streets. Another factor that must be considered when undertaking sewer separation in highly urbanized and concentrated commercial areas is the potential requirement for internal plumbing separation in large buildings including retail, office, industrial, multi-story apartments and institutional (e.g., churches, schools, government). The cost of this activity will be highly variable depending upon the specific location, building age, structure type, modernization, presence of asbestos, willingness of the building owner, etc. Sewer separation involving concentrated commercial areas should include interior inspections to determine the need for separation of the interior plumbing. Once a determination has been made to separate portions of the interior plumbing of the building, provisions then need to be made to conduct detailed investigations and prepare detailed plans and specifications for each location. The added cost for engineering and for construction for interior building plumbing modification would need to be evaluated on a case by case basis.

Sewer separation in the Clinton Street CSO service area is further complicated by the fact that the Downtown Central Business District, the Armory Square Historic District, the Syracuse University Hill Area, and the industrial/residential areas of the City's near westside are included within the service area. Sewer separation within these important business districts of downtown Syracuse would result in negative economic impacts associated with such a widespread and disruptive project. These conditions would also further increase the unit cost per linear foot to accomplish sewer separation within these areas. In addition, the County has agreed to assume responsibility for internal plumbing modifications for commercial structures impacted by sewer separation within the service area.

Sewer separation provides the ability to treat the sanitary wastewater from the separated areas at the Metro plant while storm water continues to discharge to Onondaga Creek. As such, sewer separation provides a high degree of pollutant removal as it relates to the sanitary component of the CSO discharge. Operation and maintenance requirements associated with the sewer separation CSO abatement approach are generally low when compared to conveyance and treatment facilities.

Sewer separation does not, however, eliminate the contamination that is inherently associated with separate storm water discharges, namely:
- Suspended solids
- Oil and grease
- Antifreeze
- Trash/floatables
- Pathogens
- Heavy metals
- Nutrients
- Organics
- Pesticides
- Fertilizers.

In addition, it is anticipated that forthcoming federal requirements may require the implementation of some form of treatment for storm water discharges that are believed to be impacting the ability to satisfy the water quality standards established for a particular watercourse. If sewer separation were to be implemented, the City of Syracuse would be responsible for providing the required storm water treatment.

Table 5-1 presents a summary overview of the advantages and disadvantages of the sewer separation CSO abatement approach for the Clinton Street CSO Service Area.

Table 5-1. Sewer separation advantages/disadvantages
Advantages
Separates sanitary wastewater from combined sewage for separate treatment at Metro
Provides high degree of pollutant removal, including nutrients, contained in sanitary sewage
Low operation and maintenance requirements in comparison to other CSO abatement approaches

Disadvantages
Requires disconnection of existing building sewers from combined sewer to new sanitary sewer (highly disruptive construction in urban areas)
May require building replumbing to separate sanitary piping from roof drain piping
Does not eliminate contamination associated with urban stormwater runoff
     Suspended solids
     Oil and grease
     Antifreeze
     Trash, floatables
     Pathogens
     Heavy metals
     Nutrients
     Organics
Larger separate stormwater discharges will likely require separate treatment to comply with forthcoming Federal Standards
High initial capital cost in comparison to RTF CSO abatement approaches
Extended implementation period when compared to RTF implementation period; results in delayed water quality benefits

Th general basis of design for the sewer separation CSO abatement approach would be consistent with other County sewer separation projects recently completed or currently under design. A new sanitary sewer system (with ownership and maintenance responsibility assumed by the City of Syracuse), sized to accommodate the service area sanitary wastewater flows, would be installed beneath city streets parallel to the existing combined sewer system. Building service laterals would be disconnected from the existing combined sewer and connected to the new sanitary sewer system. Internal plumbing modifications would be implemented, as necessary, to disconnect non-sanitary building flows from the service laterals. Disturbed water services would be replaced from the water main to the curb water valve. Streets and sidewalks disturbed by the installation of the new sanitary sewer system would be reconstructed to pre-existing or improved conditions. Graphic representations depicting the conversion of a typical combined sewer system to a separate sanitary sewer and storm sewer system are presented on Figures 2-1 and 2-2.

To develop appropriate cost estimates with the three alternative sewer separation approaches described above, a land use analysis of the service area was conducted. Costs to implement sewer separation in residential areas are generally less than in non-residential (concentrated commercial) areas due to the additional utility conflicts, urban congestion, more complex internal plumbing systems, etc., associated with non-residential (concentrated commercial) areas.

To establish the approximate land use areas associated with each individual Clinton Street CSO drainage basin, the drainage basin boundaries were overlayed on a map provided by the Syracuse-Onondaga County Planning Agency entitled "Existing Land Uses," dated March 2000. Using the detailed "mile-square" maps of the City of Syracuse combined/sanitary/storm sewer systems, as prepared by the City of Syracuse, Department of Planning, dated 1965, the estimated length of combined sewer that would require sewer separation, by residential and non-residential (commercial) land use area, was developed. Table 5-2 presents a summary of these data. These data will be used to calculate estimated costs for the three sewer separation CSO abatement approaches described in Section 5.2.

Table 5-2. Residential/non-residential (commercial) estimated sewer lengths for individual CSO drainage basins
	Length of new sanitary sewer
CSO drainage basin	Residential* (LF)	Non-residential* (LF)
027	2,695	28,520
028	1,513	3,216
029	0	1,635
030	15,362	35,499
031	1,066	1,492
032	1,664	1,942
033	1,434	1,948
034	6,813	27,563
035	1,069	2,352
036	15,897	13,222
TOTAL	47,513	117,389
*Based on length of existing sewer shown on sewer maps prepared by City of Syracuse, Department of City Planning, 1965. LF = Linear Feet

5.3 Regional storage with no disinfection

Regional storage with no disinfection may be appropriate for use with three of the four most viable CSO abatement approaches. These are as follows:

A. A full service area storage facility to provide storage for all CSOs (027, 028, 029, 030, 031, 032, 033, 034, 035, and 036) in the Clinton Street CSO service area;

B. A partial service area storage facility to provide storage for CSOs 027, 029, 030, 034, and 036, with sewer separation for the remaining portions of the service area; and

C. A partial service area storage facility to provide storage for CSOs 027, 029, 030, 033, 034, 035, and 036, with sewer separation for the remaining portions of the service area.

Each of the storage facilities described above would be sized to achieve full compliance with the Clinton Street ACJ CSO bacterial requirements. In addition, as described in Section 2.2, the storage facilities will provide both floatables removal and CSO volume capture.

In order to determine the design storage volumes for the three different sized regional storage facilities described above, EEA coordinated with modeling consultant Brown and Caldwell to execute the Annual Simulation Fecal Coliform Model for Onondaga Lake (bacteria model) assuming a storage facility with no disinfection in lieu of a regional treatment facility including in-line storage with disinfection (RTF) for the Clinton Street CSO service area. The results of these bacteria model runs are presented as Scenarios 3, 4, and 5 in the Brown and Caldwell memorandum included as Appendix A.

Click here for Appendix A. Bacterial model update for Onondaga Lake.

The three regional storage conditions were also analyzed at the two most preferential sites for CSO abatement facilities (i.e., Clinton Station and Dickerson Street) as determined in Section 3.4. These design storage volumes are summarized below:

Regional storage description	Design Storage Volume
Clinton Station
Full service area storage facility	21 MG
Storage facility at site with sewer separation west of Onondaga Creek (excluding 036)	18 MG
Storage facility at site with sewer separation west of Onondaga Creek and north of Tully Street (excluding 036)	19 MG
Dickerson Street
Full service area storage facility	21 MG
Storage facility at site with sewer separation west of Onondaga Creek (excluding 036)	18 MG
Storage facility at site with sewer separation west of Onondaga Creek and north of Tully Street (excluding 036)	19 MG

Regardless of the final selected site for the regional storage facility, it is expected that influent flow for the facility will be accomplished by gravity discharge. Following the storm event, pumping facilities would be provided to discharge the stored flow to the MIS for subsequent treatment at Metro. The general design basis for the regional storage facility would be as follows:

The storage capacity associated with the regional storage facility requires that this CSO abatement approach use more land area than with a vortex separator treatment system or an ORF treatment system.

Based on a preliminary conceptual layout of the conveyance pipelines for the Clinton Street CSO service area and the associated pipeline invert and available land area at the two most preferential sites, the preliminary conceptual depth of a regional storage facility would be approximately 45 feet. Based on this depth, a regional storage facility will require approximately 35% more land area than a vortex separator treatment system and approximately 6% more land area than an ORF treatment system.

A summary of the principal advantages and disadvantages of the regional storage (with no disinfection) CSO abatement/treatment approach is presented in Table 5-3.

Table 5-3. Regional storage (with no disinfection) advantages / disadvantages
Advantages	Disadvantages
Captures higher volume storms for post-storm treatment at Metro	Land area requirement (2-3 acres) results in limited siting alternatives within an urban area
High degree of settleable solids, TSS, BOD, TKN, P and floatables removal	Larger consolidation pipelines required for regional storage facilities will require deeper and wider excavation areas in comparison to sewer separation
Provides capture and treatment of storm water pollutants as well as sanitary wastewater pollutants
Disruption due to construction is confined to a smaller area in comparison to sewer separation	Does not provide back-to-back storm protection for non-disinfected bacteria laden discharges.
Existing sanitary connections and storm leaders within buildings in the urban area are undisturbed	Requires additional land area requirements in comparison to vortex separator facility and ORF
Smaller above grade facilities mean less visual impact in comparison to vortex and overflow retention facility (ORF)	Requires larger capacity pumps to dewater the facility in the same amount of time as the vortex separator facility and ORF
Conveys larger volume of CSO to Metro for treatment in comparison to vortex and ORF	May not allow permanent closure of CSOs
	For Clinton Street CSO service area, MIS available capacity limits total storage allowable storage volume, requiring additional, more costly sewer separation

It should be noted that a flow capacity evaluation of the County MIS was performed by modeling consultant Brown and Caldwell to assess the capability of the MIS to accept the pump back of captured CSO from a full storage facility over a 48-hour period (maximum pump back period established by NYSDEC) for the Clinton Street CSO service area. A copy of the MIS flow capacity evaluation memorandum prepared by Brown and Caldwell is included as Appendix G.

Click here for Appendix G. Memorandum: MIS flow capacity evaluation.

As noted in the MIS flow capacity evaluation memorandum, at the Clinton Street location, the available capacity (Qa) of the MIS is estimated to be 14.3 million gallons per day (mgd). The proposed design for the Midland Avenue CSO in-line storage/RTF, which will be located upstream of the Clinton CSO service area, includes a total storage volume of 8.45 mgd. Assuming that dewatering (pump back) of a fully stored Midland Avenue CSO in-line storage/RTF facility will occur coincident with dewatering (pump back) of a full Clinton CSO service area storage facility, the available capacity (Qa) of the MIS at the Clinton Street location will be reduced by 4.23 mgd (8.45 mgd ö 2 days) to approximately 10.1 mgd (14.3 mgd - 4.23 mgd). Assuming the same maximum 48-hour (2 day) pump back period for a Clinton Street CSO regional storage facility, the maximum storage volume that can be implemented for the Clinton Street CSO service area is 20.2 MG (10.1 mgd x 2 days). As indicated by the required storage volume data previously presented, a full service area storage facility at 21 MG exceeds the ability of the existing MIS to accept the pump back of the stored CSO for this facility over a 48-hour period. Therefore, additional facilities would need to be provided to convey the excess volume of stored CSO i.e., 0.8 MG (21 MG - 20.2 MG), to Metro for treatment. Alternatively, additional sewer separation would need to be implemented to reduce the full service area storage facility volume to 20.2 MG. Both approaches would require that these additional costs be added to the base storage facility cost.

5.4 In-line storage/vortex separation with high-rate disinfection

In-line storage/vortex separation with high-rate disinfection, as an RTF, may be appropriate for use with three of the four most viable CSO abatement approaches. These are as follows:

A. A full service area vortex separator to treat all CSOs (027, 028, 029, 030, 031, 032, 033, 034, 035, and 036) in the Clinton Street CSO service area;

B. A partial service area vortex separator to treat CSOs 027, 029, 030, 034, and 036, with sewer separation provided for the remaining portions of the service area; and

C. A partial service area vortex separator to treat CSOs 027, 029, 030, 033, 034, 035, and 036, with sewer separation provided for the remaining portions of the service area.

Pursuant to the requirements of the ACJ, the CSO Abatement Program is required to provide high-rate treatment, including floatables removal, settleable solids removal, and disinfection of CSOs up to the 1-year design storm event. As described in Section 2.2, vortex separation with high-rate disinfection, designed for the 1-year design storm event, will achieve these objectives.

The three alternative vortex separator facilities were also analyzed at the two most preferential sites for CSO abatement facilities (i.e., Clinton Station and Dickerson Street) as determined in Section 3.4. These 1-year design storm flow rates are summarized below:

Vortex separator description	1-yr design storm flow rate
Full service area vortex separator	755 cfs
Vortex separator at site with sewer separation west of Onondaga Creek (excluding 036)	660 cfs
Vortex separator at site with sewer separation west of Onondaga Creek and north of Tully Street (excluding 036)	700 cfs
Dickerson Street
Full service area vortex separator	755 cfs
Vortex separator at site with sewer separation west of Onondaga Creek (excluding 036)	660 cfs
Vortex separator at site with sewer separation west of Onondaga Creek and north of Tully Street (excluding 036)	700 cfs

Regardless of the final selected site for the in-line storage/vortex separator treatment system, influent pumping will be required to "lift" the collected CSO flow into the vortex separator system to permit gravity discharge of treated flows from the treatment system into Onondaga Creek. The general design basis for the in-line storage/vortex separator treatment would be as follows:

For planning purposes, the vortex separator treatment system was considered to include USEPA swirl concentrator treatment units. Figure 2-3 depicts a typical USEPA vortex separator (swirl concentrator). In addition, high-rate disinfection following the USEPA vortex solids separator treatment, previously documented by USEPA demonstration projects to achieve up to three log bacterial reduction with a 5-minute detention time in conjunction with high intensity mixing, will be used as the basis for achieving the required bacterial reductions pursuant to the ACJ. Dechlorination using a 1-minute detention time will also be included to reduce potential toxicity issues that may be associated with chlorinated discharges.

A summary of the principal advantages and disadvantages of the in-line storage/vortex separator (with high-rate disinfection) CSO treatment approach is presented in Table 5-4.

TABLE 5-4. IN-LINE STORAGE/VORTEX SEPARATOR (WITH HIGH-RATE DISINFECTION)—ADVANTAGES/DISADVANTAGES
Advantages	Disadvantages
Designed to operate under all, including extremely high, flow conditions	Larger consolidation pipelines required for regional treatment facilities will require deeper and wider excavation areas in comparison to sewer separation
Reduced land area requirements in comparison to ORF alternative	May not allow permanent closure of CSOs
High degree of settleable solids and floatables removal
Provides sufficient treatment for downstream disinfection
Provides capture and treatment of storm water pollutants as well as sanitary wastewater pollutants
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

5.5 In-line storage/ORF with high-rate disinfection

As discussed in Section 4, in-line storage/ORF with high-rate disinfection, as an RTF, may be appropriate for use with the same three CSO abatement approaches as evaluated for the vortex separator, i.e.:

A. A full service area ORF to treat all CSOs in the Clinton Street CSO service area;

B. A partial service area ORF to treat CSOs 027, 029, 030, 034, and 036, with sewer separation provided for the remaining portions of the service area; and

C. A partial service area ORF to treat CSOs 027, 029, 030, 033, 034, 035, and 036, with sewer separation provided for the remaining portions of the service area.

As with the vortex separator RTF, the design basis for the ORF is to provide floatables removal, settleable solids removal, and disinfection of CSOs up to the 1-year design storm event. The peak design flow rates for the three different-sized ORFs described above, at the two most preferential RTF sites, would be the same as those defined previously for the vortex separator RTF.

Similar to the vortex separator RTF, the following general design basis of the ORF will be required.

As described previously in Sections 2.2 and 2.3, ORFs, while performing as a high-rate primary sedimentation process prior to disinfection, are generally sized to retain a specific storm event. Sizing the ORF to capture and treat all service area CSOs up to the 1-year design storm event, with adequate disinfection of excess flows prior to discharge, will permit compliance with the County's ACJ requirements. For this reason, the ORF design basis was selected on the 1-year design storm volume, with post-retention disinfection facilities provided to achieve a 5-minute disinfection/1-minute dechlorination contact time at the peak service area flow rate, in the event back-to-back storms are delivered to the ORF. For the three different-sized ORFs previously described, the 1-year design flow volumes for the two most preferential abatement facilities sites are as follows:

ORF description	1-yr design storm flow volume
Clinton Station
Full service area ORF	16.0 MG
ORF at site with sewer separation west of Onondaga Creek (excluding 036)	14.3 MG
ORF at site with sewer separation west of Onondaga Creek and north of Tully Street (excluding 036)	15.1 MG
Dickerson Street
Full service area ORF	16.0 MG
ORF at site with sewer separation west of Onondaga Creek (excluding 036)	14.3 MG
ORF at site with sewer separation west of Onondaga Creek and north of Tully Street (excluding 036)	15.1 MG

The ORF, due to its design basis, provides more storage capacity for small intensity/duration storm events than the vortex separator RTF due to its inherently larger design volume. It does, however, provide less storage capacity than a regional storage facility. The captured flow is then pumped back to the MIS for treatment at Metro following the storm event.

The additional storage capacity associated with the ORF requires that the ORF treatment system use more land area than the vortex separator treatment system, however, it would require less land area than a regional storage facility. Based on a preliminary conceptual layout of the conveyance pipelines for the Clinton Street CSO service area and the associated pipeline inverts, the preliminary conceptual depth of an ORF treatment system would be approximately 40 feet. Based on this depth, for the 1-year design storm flows/volumes being used for the Clinton Street CSO service area, an ORF treatment system will require approximately 25% more land area than a vortex separator treatment system.

Because the ORF treatment system captures and stores more smaller intensity rainfall events, there would be slightly higher operation and maintenance requirements for this ORF treatment system when compared to the vortex separator treatment system. The ORF will, however, capture more flow for treatment at Metro than the vortex separator treatment system. The ORF treatment system also does not have the high degree of flexibility to provide effective pretreatment prior to disinfection under extremely high flow conditions, in excess of the 1-year design storm event, that the vortex separator treatment system provides. Under extremely high flow conditions, the ORF treatment system is susceptible to solids washout from the ORF into the post-treatment disinfection system, and disinfection effectiveness may be impacted.

A typical ORF is presented on Figure 2-10. Table 5-5 presents a summary of the principal advantages and disadvantages of the in-line storage/ORF (with high-rate disinfection) CSO treatment approach.

TABLE 5-5. IN-LINE STORAGE/ORF (WITH HIGH-RATE DISINFECTION)—ADVANTAGES/DISADVANTAGES
Advantages	Disadvantages
High degree of settleable solids and floatables removal	Land area requirement (2-3 acres) results in limited siting alternatives within an urban area
Provides sufficient treatment for downstream disinfection Provides capture and treatment of storm water and sanitary wastewater	Larger consolidation pipelines will require deeper and wider excavation areas than sewer separation
Disruption due to construction is confined to a smaller area in comparison to sewer separation	Less efficient during high flow rates in comparison to vortex separator facility
Existing sanitary connections and storm leaders within buildings in the urban area are undisturbed	Requires additional land area requirements in comparison to vortex separator facility
Smaller above grade facilities will result in less visual impact in comparison to vortex separator facility	Requires larger capacity pumps to dewater the facility in the same amount of time as the vortex separator facility
Conveys a larger volume of CSO to Metro for treatment in comparison to a vortex separator facility	May not allow permanent closure of CSOs Above grade facilities will have more visual impact in comparison to regional storage facility

5.6 Cost estimates

A summary listing the most feasible CSO abatement approaches and preferential storage/RTF sites is presented in Table 5-6. A total of 19 alternative options have been identified for further cost evaluation.

TABLE 5-6. MOST FEASIBLE CSO ABATEMENT APPROACHES AND PREFERENTIAL SITES
Abatement approach
1. Storage/RTF at Clinton Station Site
a. Storage - no sewer separation
b. Storage (separate CSO 028, 031, 032, 033, 035)
c. Storage (separate CSO 028, 031, 032)
d. RTF (vortex separator) - no sewer Separation
e. RTF (separate CSO 028, 031, 032, 033, 035)
f. RTF (separate CSO 028, 031, 032)
g. RTF (orf) - no sewer separation
h. RTF (separate CSO 028, 031, 032, 033, 035)
i. RTF (separate CSO 028, 031, 032)
2. Storage/rtf at dickerson street site
a. Storage - no sewer separation
b. Storage (separate CSO 028, 031, 032, 033, 035)
c. Storage (separate CSO 028, 031, 032)
d. RTF (vortex separator) - no sewer separation
e. RTF (separate CSO 028, 031, 032, 033, 035)
f. RTF (separate CSO 028, 031, 032)
g. RTF (orf) - no sewer separation
h. RTF (separate CSO 028, 031, 032, 033, 035)
i. RTF (separate CSO 028, 031, 032)
3. Complete sewer separation

Preliminary construction cost estimates were developed for the 19 alternative options to preliminarily screen these options.

Based on the CDM/C&S memorandum, the following unit costs (updated to February 2005 costs, ENRCCI = 7298) were determined to be applicable and reflective of the cost to implement sewer separation within the Syracuse metropolitan area. These unit costs for sewer separation include disconnection and re-plumbing of internal building storm water plumbing systems for non-residential buildings; replacement of the sanitary lateral service lines to the curb or to the building where modifications to private plumbing is required; replacement of disturbed water services from the main to the curb water valve; and restoration of sidewalks, curbing, and pavement.

Sewer separation unit costs (per linear foot of new sanitary sewer to be installed):
A. Residential Areas - $823/linear foot
B. Non-Residential (Commercial) Areas - $819/linear foot
(Note: the above per linear foot costs include a 10% contingency factor as suggested in the CDM/C&S memorandum; the above per linear foot costs are based on a February 2005 ENRCCI of 7298.)

To determine the estimated construction costs for the various sewer separation approaches identified as being appropriate to further evaluate, the total linear footage of residential and non-residential (commercial) new sanitary sewer to be installed under the alternative approaches was defined. Table 5-7 presents the residential and non-residential linear footage of new sanitary sewer to be installed for each of the three most viable sewer separation alternatives for the Clinton Street CSO service area determined previously.

TABLE 5-7. RESIDENTIAL/NON-RESIDENTIAL SEWER SEPARATION LINEAR FOOTAGE*
Sewer separation alternative	Residential	Non-residential [Commercial]
Separate 028, 031, 032	4,243	6,650
Separate 028, 031, 032, 033, 035	6,746	10,950
Complete service area sewer separation	47,513	117,389
Note: *Linear feet of new separate sanitary sewer to be installed.

Table 5-8 presents the estimated construction cost for these same three sewer separation alternatives.

TABLE 5-8. RESIDENTIAL/NON-RESIDENTIAL SEWER SEPARATION ESTIMATED CONSTRUCTION COSTS*
Sewer separation alternative	Residential	Non-residential [commercial]	Total
Separate 028, 031, 032	$3,492,000	$5,446,000	$8,938,000
Separate 028, 031, 032, 033, 035	5,552,000	8,968,000	14,520,000
Complete service area sewer separation	39,103,000	96,142,000	135,245,000
*Note: Does not include costs for rehabilitation of existing combined sewer lines. Costs based on Feb 2005 dollar (ENRCCI=7298)

To determine the estimated construction costs for the CSO abatement approaches that would utilize a regional storage or in-line storage/treatment facility (either vortex separator or ORF), preliminary conceptual planning layouts were developed for each of the two preferential sites.

Figures 5-1, 5-2, and 5-3 depict the preliminary planning layout of an RTF (vortex separator shown) and potential CSO conveyance pipelines for the Clinton Station site, and Dickerson Street site (east and west options), respectively. The preliminary planning layout for storage facilities or ORF RTFs would be similar to those presented on Figures 5-1, 5-2, and 5-3, with the exception that the storage facilities area would be approximately 35% greater than that shown for the vortex separator RTF and the ORF facilities area would be approximately 25% greater than that shown for the vortex separator.

Fig 5-1: preliminary planning layout: RTF and potential CSO conveyances, Clinton Station

Figure 5-2: Dickerson Street site (east option)

Figure 5-3: Dickerson Street site (west option)

Preliminary construction cost estimates were developed for the RTFs and conveyance pipelines based upon the preliminary planning layouts depicted on Figures 5-1 and 5-3 (Note: Estimated construction costs were developed for the Dickerson Street west option only for preliminary screening purposes, as the Dickerson Street east option estimated construction costs are expected to be generally consistent with the west option). Due to the fact that, at this facilities planning level, there are more project unknowns associated with the storage facility and RTF (vortex separator and ORF) construction implementation than are associated with the sewer separation CSO abatement approach, a 25% construction contingency was included in the estimated construction costs. Table 5-9 presents a summary of the estimated construction costs for the 19 CSO abatement options for the Clinton Street CSO service area.

TABLE 5-9. CSO ABATEMENT ALTERNATIVES ESTIMATED CONSTRUCTION COSTS ($000,000)
Abatement approach	Convey- ances	Storage/ RTF	Sewer sep	Total
1. Storage/RTF at Clinton Station Site
a. Storage - No Sewer Separation	$19.0	$60.7	$0	$79.7
b. Storage (Separate CSO 028, 031, 032, 033, 035)	14.3	52.0	14.5	80.8
c. Storage (Separate CSO 028, 031, 032)	14.8	54.9	8.9	78.6
d. RTF (Vortex Separator) - No Sewer Separation	19.0	33.0	0	52.0
e. RTF (Separate CSO 028, 031, 032, 033, 035)	14.3	28.9	14.5	57.7
f. RTF (Separate CSO 028, 031, 032)	14.8	30.6	8.9	54.3
g. RTF (ORF) - No Sewer Separation	19.0	57.3	0	76.3
h. RTF (Separate CSO 028, 031, 032, 033, 035)	14.3	51.2	14.5	80.0
i. RTF (Separate CSO 028, 031, 032)	14.8	54.1	8.9	77.8
2 Storage/RTF at Dickerson Street Site (West Option)
a. Storage - No Sewer Separation	22.5	66.7	0	89.2
b. Storage (Separate CSO 028, 031, 032, 033, 035)	18.4	57.2	14.5	90.1
c. Storage (Separate CSO 028, 031, 032)	18.4	60.4	8.9	87.7
d. RTF (Vortex Separator) - No Sewer Separation	22.5	33.0	0	55.5
e. RTF (Separate CSO 028, 031, 032, 033, 035)	18.4	28.9	14.5	61.8
f. RTF (Separate CSO 028, 031, 032)	18.4	30.6	8.9	57.9
g. RTF (ORF) - No Sewer Separation	22.5	63.1	0	85.6
h. RTF (Separate CSO 028, 031, 032, 033, 035)	18.4	56.4	14.5	89.3
i. RTF (Separate CSO 028, 031, 032)	18.4	59.5	8.9	86.8
3 Complete Sewer Separation	0	0	135.2	135.2
Notes: (1) Costs have been rounded to the nearest $100,000. (2) Costs based on November 2005 dollars (ENRCCI = 7298)

In addition to construction cost, O&M costs will impact the overall cost-effectiveness of a particular option. To assess this impact, estimated annual O&M costs were developed for the most feasible CSO treatment technologies/approaches at a single site, in addition to full sewer separation of Clinton Street CSO service area. Due to the fact that all of the CSO treatment technologies/approaches at the Clinton Station site were determined to have lower estimated construction costs than if implemented at the Dickerson Street site (see Table 5-9) O&M costs were developed for these CSO technologies/approaches for a total present worth cost comparison. Table 5-10 presents the estimated annual O&M costs for the CSO treatment technologies/approaches at the Clinton Street site plus full sewer separation for the Clinton Street CSO service area.

TABLE 5-10. ESTIMATED ANNUAL OPERATION AND MAINTENANCE COSTS
Abatement approach	Est annual O&M cost
1. Storage/RTF at Clinton Station Site
a. Storage - No Sewer Separation	$656,000
b. Storage (separate CSO 028, 031, 032, 033, 035)	584,000
c. Storage (separate CSO 028, 031, 032)	617,000
d. RTF (vortex separator) - No Sewer Separation	1,026,000
e. RTF (separate CSO 028, 031, 032, 033, 035)	901,000
f. RTF (separate CSO 028, 031, 032)	957,000
g. RTF (ORF) - no sewer separation	659,000
h. RTF (separate CSO 028, 031, 032, 033, 035)	586,000
i. RTF (separate CSO 028, 031, 032)	617,000
3. Complete sewer separation	46,000
Costs based on Feb 2005 dollars (ENRCCI=7298)

Table 5-11 presents the total estimated project costs for the CSO abatement technologies/approaches at the Clinton Station site plus full sewer separation for the Clinton Street CSO service area.

TABLE 5-11. ESTIMATED PROJECT COSTS ($000,000)
Abatement approach	Construc- tion (1)	Site mitigation (2)	Subtotal	Project-related (3)	Total
1. Storage/RTF at Clinton Station site
a. Storage - No Sewer Separation	$79.7	$6.3	$86.0	$19.9	$105.9
b. Storage (separate CSO 028, 031, 032, 033, 035)	80.8	6.3	87.1	20.2	107.3
c. Storage (separate CSO 028, 031, 032)	78.6	6.3	84.9	19.7	104.6
d. RTF (vortex separator) - no sewer separation	52.0	6.3	58.3	13.0	71.3
e. RTF (separate CSO 028, 031, 032, 033, 035)	57.7	6.3	64.0	14.4	78.4
f. RTF (separate CSO 028, 031, 032)	54.3	6.3	60.6	13.6	74.2
g. RTF (ORF) - No Sewer Separation	76.3	6.3	82.6	19.1	101.7
h. RTF (separate CSO 028, 031, 032, 033, 035)	80.0	6.3	86.3	20.0	106.3
i. RTF (separate CSO 028, 031, 032)	77.8	6.3	84.1	19.5	103.6
3. Complete sewer separation	135.2	0	135.2	33.8	169.0

Notes: (1) Based on Feb 05 dollars (ENRCCI = 7298) rounded.
(2) Site mitigation costs include temporary and permanent replacement parking, site enhancements, residential relocations, business relocations, and demolition costs, as warranted. Special Costs Associated with Site includes property acquisition, architectural enhancements, contaminated soil disposal and construction access bridge, as warranted.
(3) Project related costs include engineering, legal and administrative costs estimated to equal 25% of the Estimated Construction Cost.

Using the O&M cost data presented in Table 5-10, a 25-year present worth cost comparison was developed for each of the most viable CSO abatement technologies/approaches described above. The 25-year period for the present worth analysis was selected as this generally represents the standard useful life for installed CSO abatement facilities, including mechanical equipment, pumps, instrumentation, etc. Table 5-12 presents the results of the present worth analysis.

TABLE 5-12. PRESENT WORTH ANALYSIS ($000,000)
Abatement approach	Est proj cost (1)	Est annual O&M	Present worth (2)
1. Storage/RTF at Clinton Station site
a. Storage - no sewer separation	$105.9	$0.656	$115.3
b. Storage (separate CSO 028, 031, 032, 033, 035)	107.3	0.584	115.6
c. Storage (separate CSO 028, 031, 032)	104.6	0.617	113.4
d. RTF (vortex separator) - No Sewer Separation	71.3	1.026	85.9
e. RTF (separate CSO 028, 031, 032, 033, 035)	78.4	0.901	91.3
f. RTF (separate CSO 028, 031, 032)	74.2	0.957	87.9
g. RTF (ORF) - No Sewer Separation	101.7	0.659	111.1
h. RTF (separate CSO 028, 031, 032, 033, 035)	106.3	0.586	114.7
i. RTF (separate CSO 028, 031, 032)	103.6	0.617	112.4
3. Complete sewer separation	169.0	0.046	169.7
Notes: (1) Based on Feb 05 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 analysis presented in Table 5-12, it is concluded that an in-line storage/vortex separator RTF at a final selected preferred site (Approach 1d, Table 5-13) will be the most cost effective approach for abating CSOs in the Clinton Street CSO service area.

Click to enlarge

To further evaluate the cost-effectiveness of implementing an in-line storage/vortex separator RTF at the two preferential site locations, an assessment of the various anticipated mitigation measures that would be required at each of these sites was undertaken. A discussion of these anticipated mitigation measures is presented below.

Clinton Station

If the RTF were to be located at the Clinton Station site, replacement parking would be required both during construction and permanently after construction is completed. At the present time, the Clinton Station site provides low-cost parking for both employment and recreational activities in the Central Business District. Public input from the Downtown Committee of Syracuse, the Armory Square Merchants Association, and the City of Syracuse have confirmed that the loss of low-cost parking in close proximity to employees and patrons of the Armory Square Historic District will have negative impacts to the future prosperity for these areas. It is estimated that permanent replacement parking will be required for approximately 300 to 400 vehicles at the Clinton Station site. In addition, temporary replacement parking will need to be provided for approximately 450 vehicles during construction.

In the event an ORF or storage facility were to be located at the Clinton Station site, its location at the north end of the parking lot will necessitate closing of the existing tunnel beneath the adjacent elevated railway tracks during construction due to its larger size in comparison to a vortex separator RTF. This condition would alter access to and use of the parking lot during construction. Requirements for permanent replacement parking at the Clinton Station site may be reduced if the ORF or storage facility is designed to accommodate permanent replacement parking above the underground tankage for these facilities.

In addition to parking mitigation noted above, construction access to the Clinton Station site is severely restricted. The main entry to the site is at the extreme southern portion of the site. This entry point will need to be maintained for access to parking spaces that will not be disturbed by construction of the RTF. In addition, there is an access tunnel that is located under the railroad tracks on the east side of the site. Height clearances will not allow access of most major pieces of construction equipment. On the west side of the site, there is an old railroad bridge that spans Onondaga Creek and connects the site with Fabius Street and the West Street Arterial. This bridge is unused and in a state of disrepair. Construction access to the Clinton Station site will require the construction of a new access bridge.

Dickerson Street

Construction of an RTF at the Dickerson Street site could be undertaken in several ways.

One alternative (east option) could include demolishing the existing Ward Supply Company building and reconstructing the existing Rescue Mission Recreation Center at a different location on the Rescue Mission property. This may entail raising abandoned buildings along Seymour Street to reconstruct the Rescue Mission Recreation Center in this general vicinity. It may also be necessary to provide additional improvements to other portions of the Rescue Mission property that are in close proximity to the Dickerson Street site.

A second alternative (west option) could include demolishing the existing Ward Supply Company building, relocating several active businesses on the west side of Granger Street, and demolishing the business buildings.

The land area available for both the Dickerson Street east and west options would severely limit contractor staging areas for construction for the previously identified cost-effective in-line storage/vortex separator CSO abatement facilities for the Clinton Street CSO service area. (Note: as presented previously, the vortex separator CSO treatment technology requires less land area than both the regional storage technology [35% less] and the ORF technology [25% less]). Therefore, additional property acquisitions and/or permissible use by the nearby property owners would be required to provide the necessary contractor staging areas to implement these CSO abatement technologies at the Dickerson Street (east and west options) site.

As part of this facilities planning effort, a Phase 1A archeological literature review and assessment was performed for each of the preferential site locations noted above and the preliminary conveyances routing. This information is included in the companion Clinton CSO Abatement: Environmental Information Document (Feb 2005) to this Facilities Plan. Based upon the past record of commercial/industrial activity identified in the Phase 1A literature review and assessment for the three sites, site environmental remediation activities may be required at these sites during construction.

In addition, a limited program of subsurface exploration was performed at the Clinton Station and Dickerson Street sites. These data indicate that there is a greater likelihood of adjacent/nearby building settlement due to construction activities at the Dickerson Street site rather than at the Clinton Station site. In addition existing site features (Rescue Mission Recreation Center and potential utilities located in Dickerson and Granger Streets may preclude the use of external tie-backs for temporary excavation bracing support at the Dickerson Street site.

Table 5-14 presents the estimated total project cost summary for an in-line storage/vortex separator RTF located at either the Clinton Station site or Dickerson Street West site. (Note: costs at the Dickerson Street East site are expected to be higher than the Dickerson Street West site due to the required removal and relocation of the existing Rescue Mission Recreation Center.)

TABLE 5-14. TOTAL ESTIMATED PROJECT COST(1), INCLUDING MITIGATION ($000,000) ALTERNATIVE RTF SITES
	Clinton Station Site	Dickerson Street Site (West Option)
Estimated Construction Costs	$52.0	$55.5
Estimated Site Mitigation Costs (2)	4.4	1.4
Estimated Special Costs Associated with Site (3)	1.9	2.2
Subtotal	58.3	59.1
Estimated Other Project Related Costs (4) (25% of est const cost)	13.0	13.9
Total Estimated Project Cost	$71.3	$73.0

Notes: (1) In-Line Storage/Vortex Separator RTF
(2) Includes temporary and permanent replacement parking, site enhancements, residential relocations, business relocation, and demolition costs, as warranted.
(3) Includes property acquisition, architectural enhancements, contaminated soil disposal, and construction access bridge, as warranted.
(4) Includes engineering (including construction phase services) legal, and administrative costs
Costs based on Feb 2005 dollars (ENRCCI=7298)

Estimated construction cost (see Table 5-9).

Estimated site mitigation costs (includes temporary and permanent replacement parking, site enhancements, residential relocations, business relocations, and demolition costs, as warranted).

Estimated special costs associated with site (includes property acquisition, architectural enhancements, contaminated soil disposal, and construction access bridge, as warranted).

Estimated other costs (includes engineering [including construction phase services], legal, and administrative costs; estimated at 25% of the estimated construction cost).

As identified in Section 5.6, the most cost-effective CSO abatement approach for the Clinton Street CSO service area is in-line storage/vortex separator RTF at one of the two preferential site locations. As shown in Table 5-14, in-line storage/vortex separator RTF at the Clinton Station site has the lowest estimated construction cost and the lowest total estimated project cost. Therefore, in-line storage/vortex separator RTF at the Clinton Station site is the recommended/preferred CSO abatement approach for the Clinton Street CSO service area.