HB facilities plan
Introduction
Summary
1. Basis
2. In-water system
3. Technologies
4. Sites
5. Separation
6. Alternatives
7. Scenarios

8. Recommendation
9. Schedule
Appendices

Env Info Document

Harbor Brook CSO Abatement Project Facility Plan (Aug 2005)
by Brown and Caldwell
for Onondaga County Dept of Water Environment Protection

8. Recommended Plan

As identified in Section 7.2 the recommended/preferred CSO abatement approach for the Harbor Brook service area is Scenario 5a and includes vortex separators followed by disinfection at both the Upper and Lower Basins. The Middle Basin CSOs 005 through 008 would be conveyed to the Lower Basin RTF and CSOs 009 through 013 would include FCFs. CSO 063 would also include an FCF. In addition, portions of the HBIS in the Middle Basin would be abandoned and a new interceptor constructed.

Site #4 and #10 were selected as the preferred sites for the proposed RTFs based on an evaluation of criteria identified in Section 4. Site #10 was considered more favorable over #11 due to Site #11's location in the 100-year flood plain, as well as that it would be reducing an existing green space.

The plan [Scenario 5a] is summarized below and is shown in Figures 8.1 through 8.8 for Lower, Middle and Upper Basin facilities. The figures depict the proposed facilities on separate basemaps of city streets and aerial photos.
Emerson FCF (map)
Lower Basin RTF (map)
Upper Basin RTF (map)
Upper Basin conveyance (map)
Emerson FCF (photo)
Lower Basin RTF (photo)
Upper Basin RTF (photo)
Upper Basin conveyance (photo)

Upper and lower RTFs:

CSO conveyance pipelines to collect and transport captured CSO, up to the 1-year design storm, to the vortex separator treatment systems for the Upper and Lower Basins (estimated volume of storage the conveyances will provide is 0.40 MG; 0.12 MG for the Upper RTF, 0.28 MG for the Lower RTF)
Influent stilling well/grit sump (estimated storage provided is 0.30 MG)
Coarse screening/manually cleaned trash racks
Influent pumping
Vortex solids separators to provide storage for smaller storms events and floatables and settleable solids removal for larger storm events (estimated storage provided is 0.17 MG)
Vortex solids separator underflow conveyance to the HBIS during a storm event
High-rate disinfection by chlorination/dechlorination for bacterial reduction prior to discharge to Harbor Brook (estimated storage provided is 0.97 MG)
Dewatering of the vortex separators and disinfection tank stored flows to the HBIS following a storm event
Odor control facilities
CSO 063 would be an FCF using weir-mounted mechanical screens.

For planning purposes, the vortex separator treatment systems were considered to include USEPA swirl concentrator treatment units. High-rate disinfection following the vortex separators, previously documented by USEPA demonstration projects to achieve up to three log bacterial reductions with a 5-minute contact time in conjunction with high intensity mixing, will be used as the basis for achieving the required bacterial reduction pursuant to the ACJ. Dechlorination using a 1-minute contact time will also be included to reduce potential toxicity issues that may be associated with chlorinated discharges. The total in-line storage provided is estimated to be 1.8 MG.

Middle Basin CSOs:

CSOs 005 through 008 would be conveyed to the Lower Basin RTF
FCFs using weir-mounted mechanical screens for CSOs 009 through 013
Floatables collected at each FCF would be temporarily stored and/or directed to the HBIS for treatment at Metro following each storm event
Two CSOs (006 and 008) would be eliminated through upgrades to existing pumping stations (Sackett St. and Richmond Avenue) and regulator sewer improvements.

The recommended plan was also evaluated to determine which CSOs might be permanently closed (eliminated). Based on modeling results, CSOs 004, 005, 006, 008, 015, and 016 would be permanently closed.

The total estimated project cost for the recommended plan is $55,200,000.