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Harbor Brook CSO Abatement Project Facility Plan (Aug 2005)
by Brown and Caldwell
for Onondaga County Dept of Water Environment Protection
Executive summary
A total of 18 CSOs from the Harbor Brook watershed
discharge into Harbor Brook.
The locations of all CSO outfalls and drainage areas are shown in Figure ES.1.
These areas are shown on an aerial photo in Figure ES.2.
For the purposes of developing abatement alternatives
the drainage areas have been broken up into three
general areas including the Upper, Middle and Lower
Basins.
Sanitary sewage and storm water from these areas
collect in a network of pipes that discharge into the
Harbor Brook Interceptor Sewer (HBIS). Flows in excess
of the capacity of the HBIS are relieved through
Combined Sewer Overflows (CSOs), which discharge to
Harbor Brook.
The discharge of untreated sewage through combined
sewer overflows to Harbor Brook contributes to the
discharge of floatables and conditions where the
bacterial levels in Onondaga Lake exceed the coliform
standards set in 6 NYCRR Part 703.4. However,
computer modeling has been used to demonstrate that
the disinfection of all CSOs is not required to
achieve water quality standards for bacteria in those
portions of Onondaga Lake designated as Class B.
CSOs also contribute to the release of floating solids
in violation of 6 NYCRR Part 703.2. The term floating
solids or
floatables
is used to describe those materials that float at or
near the water surface, and can include neutrally
buoyant materials that are carried along within the
flow. All alternatives that were considered meet the
water quality objectives and criteria established
through the ACJ process.
A separate
Environmental Information Document (EID)
has been developed for the Harbor
Brook CSO Abatement Project. The EID includes the
results of the Phase IA Literature Review and
Archeological Sensitivity Assessment to be completed
by Hartgen Archeological Associates, Inc. as a
subconsultant to Brown and Caldwell on sites for
CSO-related facilities which would be part of the
overall Harbor Brook CSO abatement plan.
During the compilation of this draft Facilities Plan,
County staff and design engineers met with and gave
presentations to various individuals and groups to
provide information on the purpose and status of the
Facility Plan and to obtain public input on potential
issues and concerns. Individuals included interested
county and city officials, area business people, local
school and church officials and residents of the
City's west side. In addition, public availability
sessions were held and information distributed via
direct mailings to area residents.
The County will continue its public participation
activities to solicit and receive further input from
the community. Public participation activities will
include direct mailings to area residents, holding
availability sessions in the neighborhoods near Harbor
Brook, presentations to local groups and
organizations, public information meetings and other
activities.
The original HB IWS concept included a storage
structure at the mouth of Harbor Brook along with the
associated Harbor Brook Floatables Control Facility
(HB FCF), located just upstream. The HB IWS was to be
constructed in two increments, the demonstration phase
and the full-size, both of which would provide
temporary containment of wet-weather discharges for
subsequent treatment at Metro.
All of the potential sources for the contamination on
the landside in the vicinity of the proposed IWS have
not yet been identified. In light of evidence of the
ongoing release of contamination occurring near the
mouth of Harbor Brook, any plan to capture the brook
flow in an IWS would also lead to capture of
contaminated materials which would require appropriate
disposal.
As a result of the impediments identified above, the
HB IWS is not considered a viable CSO abatement
approach for the Harbor Brook Basin. Alternatives to
the HB IWS have been developed and presented in the
following sections.
Fifteen potential sites were identified for further
evaluation of the abatement of CSOs discharging to
Harbor Brook. Fourteen potential sites were
identified along Harbor Brook for the location of
Regional Treatment Facilities (RTFs) and one site was identified
for treatment at Metro.
Floatables control facilities (FCFs) will be placed at
the site of the CSOs. Where feasible, the FCFs will be
located in existing roads. Where not feasible, the FCF
will be locatged to minimize traffic and disruption
during construction and maintenance.
and home- or business-owner disruption during
construction and maintenance.
The sites under consideration have been shown on a street map in Figure ES.3.
Fig ES.4, Aerial photo
The following criteria were developed for use in
assessing the sites that have been identified:
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Relation to residences and businesses
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Opportunities for public facilities and community enhancement
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Site availability and current usage
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Engineering and operational considerations.
Based on site characteristics and the Decision
Criteria listed above, two sites were selected for the
siting of the RTFs. These are summarized below and
shown in Figures ES.3 and ES.4.
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Site #4 is a suitable site for construction of an
RTF for the abatement of lower basin CSOs. This site
is a relatively large, privately owned property and
located in close proximity to CSOs 003 and 004. The
site is also adjacent to Harbor Brook and the HBIS.
The site is adjacent to commercial properties, easily
accessible and is currently undeveloped.
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Site #10 is located within a city block that is
primarily vacant with some adjacent commercial and
residential areas. This site is near the Brook and
the HBIS and is in close proximity to CSO 014, which
is the largest contributor of CSO in the upper basin.
The site is primarily undeveloped and accessible from
Grand Avenue, Seymour Street, Amy Street, Delaware
Street and Geddes Street. As part of the recommended
plan, this site could be used to build a new
recreational or educational facility for nearby
schools. The costs for recreational or educational
facilities are not included in the project costs.
These characteristics make this site a most suitable
location for an Upper Basin RTF.
A number of technologies have been considered viable
for the abatement of the Harbor Brook combined sewer
overflows (CSO). Although sewer separation is not a
technology but a CSO abatement option, it is included
in this section.
The various technologies considered are grouped into
floatables control and storage-treatment.
More detailed evaluations of the technologies are described further in the body of the Facilities Plan.
Floatables control.
A number of technologies were identified and evaluated
for floatables control. Those that were considered
include:
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Net bags
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Trash racks and bar screens
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Weir-mounted screens.
Storage-treatment.
A number of technologies were identified and evaluated
for storage and treatment. Those that were considered
include:
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Vortex separators
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Storage
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Overflow retention facilities
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Disinfection.
Development of treatment systems.
The technologies identified above were assembled into
treatment systems that are necessary to meet the
requirements of the ACJ. These include:
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Screening, where disinfection is not required
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ORF with in-line storage and high-rate disinfection
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Vortex separators and high-rate disinfection
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Offline-upstream storage with vortex separators and high-rate disinfection
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Off-line storage at the Metro tertiaries and treatment
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Regional off-line storage
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Sewer separation.
Four main alternatives for Harbor Brook CSO abatement
were identified as:
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Sewer separation
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Conveyance to Metro for storage and treatment
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Regional treatment facilities (RTFs)
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Floatables control facilities (FCFs)
These alternatives were further evaluated to develop a
number of scenarios for the complete abatement of CSO
discharging to Harbor Brook. Each scenario addresses
the lower, middle and upper basins and was developed
with the goal of meeting or exceeding the requirements
of the ACJ.
An overview of these scenarios is included in Table ES.1.
Description. Based on the anticipated extent of
disruption, duration of construction and the high
project cost of separating large densely urban
tributary areas, sewer separation was considered
viable only for the Middle Basin of Harbor Brook (CSOs
005, 006, 006A, 007, 008, 009, 010, 011, and 013).
The characteristics of the Middle Basin which make it
more viable for sewer separation include: fewer number
of streets and smaller volumes of CSO. Sewer
separation of the entire Harbor Brook Basin was also
presented for comparison purposes. However, sewer
separation was dismissed based upon the above factors.
Two scenarios were identified for conveyance of Harbor
Brook CSOs to Metro for storage and treatment: namely,
conveying CSOs 003 through 008, or full conveyance
(CSOs 003 to 078). For both alternatives CSO 063
would receive an FCF.
Scenario 2—Full conveyance
Description: This alternative consists of a
conveyance that would divert flow from each of the 18
Harbor Brook outfalls to Metro for storage-treatment.
In order to meet the ACJ requirements, an additional
storage facility would need to be provided to capture
the 1-year recurrence interval volume. Flows in
excess of the combined storage volume would be
conveyed to a separate tank and receive high-rate
disinfection prior to discharging to the Lake. As
such, the Metro tertiaries and new disinfection
facility would act as an Overflow Retention Facility
(ORF). The Metro tertiaries would require
retrofitting to be utilized for this purpose.
Scenario 3—Lower basin conveyance
Description: The CSOs located in the Lower Basin
(CSOs 003 and 004) as well as a portion of the Middle
Basin CSOs (005, 006, 006A, 007, and 008) would be
conveyed to a pumping station and to the Metro
tertiaries for storage and subsequent treatment.
Wet-weather volumes greater than the 1-year recurrence
interval volume would be discharged through the
existing overflows and/or at the new pump station
outfall.
Based upon costs, scenarios 2 and 3 were dismissed.
Based on the location of the major CSOs and the
characteristics of suitable local sites, it was
considered practical to construct two separate
Regional Treatment Facilities (RTFs) in the Harbor
Brook combined-sewer basin. The first, identified as
the Upper Basin RTF, would address the Upper Basin
CSOs and would be designed to address a portion of the
Middle Basin. The second facility, the Lower Basin
RTF, would provide CSO abatement for the Lower Basin
and would be designed to address a portion of the
Middle Basin as well.
Three technologies that were considered for
storage-treatment in combination with disinfection
were considered viable. These include an Overflow
Retention Facility (ORF), a vortex facility, and a
combination of vortex and off-line upstream storage.
In addition, a regional storage facility without
disinfection was included.
Description: FCFs have been presented as viable
alternatives for relatively smaller CSOs (CSO 005,
006A, 007, 009, 010, 011 and 013).
Since the Emerson Avenue overflow (CSO 063) does not
discharge directly from the sewer to the Brook, an FCF
would be sufficient treatment for this CSO. All of
the scenarios except full separation include an
Emerson Avenue FCF.
Replacement of HBIS
Two Middle Basin CSOs (006 and 008) would be
eliminated by improvements to the regulator sewers as
well as the Sacket Street and Richmond Avenue pumping
stations.
A common project associated with each scenario
regardless of the technologies considered is the
replacement of the Upper and Middle Basin portions of
the HBIS. The HBIS from Velasko Road north to Fayette
Street is a 30-inch slab top sewer built in the early
1900s and is in poor condition. In addition, in the
vicinity of Fowler High School, the HBIS appears to
have a significant limitation that has reduced its
capacity by more than 50 percent. As a result of
these conditions, the HBIS should be replaced from
Velasko Rd. north to Fayette Street. The Upper Basin
RTF would include abandonment of the HBIS and
utilization of a new conveyance pipeline to convey dry
weather flow to the RTF location.
Summary of basin-specific options
Table ES.1 [above] summarizes the scenarios identified above.
The table includes the approach used for each scenario
and for each of the Lower, Middle and Upper Basins.
The total project and present worth costs for each
scenario are provided for comparison purposes. In
addition, the average annual number of treated
discharges as well as the annual average discharge
volumes are shown in Table ES.1.
Table ES.2 presents the project costs, estimated annual
O&M costs and present worth costs.
| Table ES.2. Present worth analysis |
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Scenario
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Total est. project cost
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Est. annual O&M cost
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Present worth
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Scenario 1 - Sewer separation
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$261,930,000
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$53,000
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$262,700,000
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Scenario 2 - Convey and treat at Metro
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111,390,000
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450,000
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117,730,000
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Scenario 3 - Convey-treat at Metro, vortex, FCF
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91,860,000
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652,000
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101,050,000
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Scenario 4 - Vortex facilities, separation, FCF
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62,830,000
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609,000
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71,410,000
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Scenario 5 - Vortex facilities and FCF
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58,460,000
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607,000
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67,020,000
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Scenario 5a - Combo of Scenarios 5 and 6
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55,230,000
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678,000
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64,790,000
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Scenario 6 - Vortex facilities, FCFs, PS upgrades
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53,410,000
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731,000
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63,710,000
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Scenario 7 - ORFs, FCF, FCFs, PS upgrades
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68,780,000
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372,000
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74,020,000
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Scenario 8 - Vortex-offline and upstream storage facilites, FCFs, PS upgrades
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60,760,000
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552,000
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68,540,000
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Scenario 9 - ORF, regional storage, FCFs, PS upgrades
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69,810,000
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382,000
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75,190,000
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Notes: Based on ENRCCI = 7314 escalated to midpoint of construction worth cost bsed on 25-yr useful life and discount rate of 5.0%
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CSO closures
CSO closure has been considered for each of the
scenarios. For all scenarios, CSOs 004, 005, 006,
008, 015, and 016 would be permanently closed.
Additionally, CSO closure would be included as part of
any sewer separation. These closures are indicated on
Figures ES.6 and ES.7.
Based on the information presented in this report and
summarized in Table ES.1, the three more cost-effective
scenarios of the ten evaluated are 5, 5a and 6. While
Scenario 6 represents the lowest overall cost,
Scenario 5a provides the best balance of low cost,
reduced number of CSO facilities and fewer average
annual treated discharges. Therefore, Scenario 5a is
recommended as the preferred Scenario.
The locations of the proposed facilities for Scenarios
5a are shown in Figures ES.5 through ES.8.
Emerson FCF (photo)
Lower Basin RTF (photo)
Upper Basin RTF (photo)
Upper Basin conveyance (photo)
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Summary
Susan Miller, Project Deputy Director
Onondaga County Dept of Water Environment Protection