HomeMy WebLinkAboutPWC Agenda 2026-08-11 and PacketAGENDA
PUBLIC WORKS
COMMITTEE
August 11, 2026, 10:00a.m.
ZOOM Link:
https://us06web.zoom.us/j/81695207215
1. Approval of
Minutes
a. None
2. Member Comments/Concerns
a. Consider Modifications to Agenda
3. Ithaca Sanitary Sewer Joint Interceptor Study -
Phase 1 report, Phase 2 & 3 proposed scope
4. Project Updates
ITHACA SANITARY SEWER JOINT
INTERCEPTOR STUDY
PHASE 1 REPORT
PREPARED FOR:
Town of Ithaca
114 Seven Mile Drive
Ithaca, New York, 14850
PREPARED BY:
Larson Design Group
1 West Market Street, Suite 301
Corning, New York, 14830
Phone: 607.936.7076
LDG Project No. 9418-005
August 2026
TABLE OF CONTENTS
1. Executive Summary ..................................................................................................................... 1
2. Introduction and Background ....................................................................................................... 1
2.1. Project Background ................................................................................................................. 1
2.2. Phase 1 Purpose and Scope ................................................................................................... 3
3. Existing Joint Interceptor Agreement ........................................................................................... 3
3.1. Parties and Purpose ................................................................................................................ 3
3.2. Infrastructure Covered ............................................................................................................. 3
3.3. Ownership Structure and Transition Points ............................................................................. 4
3.4. Metering and Flow Monitoring ................................................................................................. 4
3.5. Financial Terms ....................................................................................................................... 5
3.6. Governance and Legal Framework ......................................................................................... 5
4. Existing Data Collection and Evaluation ...................................................................................... 5
4.1. Data Sources Received ........................................................................................................... 5
4.2. Data Evaluation ....................................................................................................................... 6
5. Field Investigation ........................................................................................................................ 7
5.1. Field Investigation ................................................................................................................... 7
5.2. Findings ................................................................................................................................... 8
6. GIS Database Development ...................................................................................................... 11
7. Phase 2 and 3 Recommendations ............................................................................................ 11
7.1. Overview and Approach ........................................................................................................ 11
7.2. Manhole Data Collection and Verification ............................................................................. 12
7.3. Pump Station and Siphon Evaluation .................................................................................... 12
7.4. Temporary Flow Metering Program ...................................................................................... 13
7.5. Data Analysis and Capacity Evaluation ................................................................................ 14
7.6. System Evaluation and Recommendations .......................................................................... 15
7.7. Reporting ............................................................................................................................... 15
TABLE OF CONTENTS
FIGURES
Figure 1 – Overview Map
Figure 2 – Field Inspection Map
Figure 3 – Interceptor Revisions
Figure 4 – Overflow Structures Map
Figure 5 – Interceptor System Components
Figure 6 – Joint Interceptor Network
Figure 7 – Boundary Meter Map
Figure 8 – Pipe Diameter Map
Figure 9 – Manholes with Photographs
Figure 10 – Rim and Invert Map
Figure 11 – Temporary Flow Metering Map
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Ithaca Sanitary Sewer Joint Interceptor Study
1. Executive Summary
The Town of Ithaca manages a sanitary sewer system serving multiple service areas and conveys
wastewater through a network of interceptor infrastructure jointly owned with the City of Ithaca prior to
reaching the Ithaca Area Wastewater Treatment Facility (IAWWTF). Because portions of the interceptor
system have been modified over time and documentation varies in completeness, the Town initiated
the Joint Sanitary Sewer Interceptor Study in coordination with the City to improve system
understanding, verify existing records, and support future capacity planning.
The study is being completed in three phases. This report documents Phase 1, which focused on
compiling and reconciling existing GIS and record information with targeted field verification. As part of
Phase 1, approximately 96 interceptor manholes were inspected to confirm flow paths, invert data, and
general condition, and limited dye testing was performed to identify and confirm flow paths.
Phase 1 results showed general agreement between field conditions and City GIS mapping; however,
several discrepancies were identified. These included revised interceptor alignments, identification of
previously unknown or undocumented shared or lightly shared interceptors, and areas where
infrastructure documented as interceptor infrastructure does not currently function as an interceptor. All
findings were incorporated into an updated GIS database and used to develop an updated joint
interceptor network.
Phases 2 and 3 will focus on system performance and capacity evaluation, including additional field
verification where needed, flow monitoring, and pump station and siphon assessments. The results will
be used to identify system deficiencies and constraints and develop recommendations for operational
and capital improvements.
Overall, Phase 1 established a more accurate and defensible understanding of the interceptor system
and provides the foundation for a capacity evaluation in Phases 2 and 3.
2. Introduction and Background
2.1. Project Background
The Town of Ithaca has a single town-wide sewer district that owns and operates multiple sanitary
sewer collection systems consisting of approximately 68 miles of 6-inch to 15-inch gravity sewer main,
approximately 14,000 linear feet of 3-inch to 8-inch force main, approximately 1,720 manholes, and 9
pump stations. Portions of the system date back to the early 1930s, with significant expansion occurring
in the 1960s, 1980s, and 1990s, resulting in the current system configuration.
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Ithaca Sanitary Sewer Joint Interceptor Study
Wastewater generated within the Town is conveyed through multiple service areas, including West
End, Inlet Island, North Side, East Hill, South Hill, and areas surrounding Cornell University. Most flows
discharge to interceptor sewers jointly owned by the Town and the City of Ithaca, while a smaller
northeastern portion of the Town is served by the Village of Cayuga Heights system and is not normally
conveyed through the jointly owned interceptors. During high-flow conditions, however, the Kline Road
bypass, which is understood to be owned by the Village of Cayuga Heights, can be utilized to direct
untreated wastewater to the joint interceptor system. The Kline Road bypass was not analyzed as part
of this study. Ultimately, flows within the interceptor system are conveyed through the City’s collection
network to the IAWWTF, which is jointly owned and operated by the City of Ithaca, Town of Ithaca, and
Town of Dryden. The IAWWTF was constructed in 1987 and has a design capacity of 13.1 MGD (peak
monthly average), with current average daily flows of approximately 6.5 MGD and peak flows reaching
up to 30 MGD. Refer to Figure 1 for an Overview Map of both the City’s and Town’s sanitary sewer
systems.
The interceptor segments jointly owned by the Town and the City include gravity sewer mains,
manholes, pump stations, siphons, and related appurtenances located within the City. These facilities
are governed under a formal Joint Interceptor Agreement that defines shared ownership and capacity
rights. Additional details regarding the agreement are provided in Section 3.
Because the Town’s wastewater flows through infrastructure located within the City prior to reaching
the treatment facility, it is important that both municipalities maintain a clear understanding of the
interceptor system, including:
• The general condition of the jointly owned assets
• The accuracy and completeness of mapping and system records
• How the interceptor system is configured and connected
• Capacity for additional flows from future development
Over time, the interceptor system has been expanded, modified, and rehabilitated. As a result, available
GIS data, record drawings, and condition information vary in completeness and format. To improve
understanding of the jointly owned interceptor system and support future planning efforts, the Town
initiated this Joint Sanitary Sewer Interceptor Study with coordination from the City.
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Ithaca Sanitary Sewer Joint Interceptor Study
2.2. Phase 1 Purpose and Scope
The purpose of the first phase of this study is to organize and evaluate available system data,
confirm/determine interceptor alignment and connectivity, begin to assess the general condition of
jointly owned interceptor infrastructure, and define additional work necessary to support a future
capacity evaluation. To manage uncertainty regarding data completeness and the level of field
investigation required, the study was broken into two phases.
This report will focus on Phase 1, which involved consolidating and reviewing existing GIS and record
information provided by the Town and City, identifying data gaps and mapping inconsistencies, and
conducting targeted field verifications. 96 interceptor manholes were inspected to confirm flow direction,
verify invert information, document general structural condition, and evaluate the consistency of GIS
mapping with observed field conditions. Targeted dye testing was also performed to confirm
downstream connectivity and interceptor alignment.
Phase 1 did not include hydraulic capacity calculations, temporary flow metering, a comprehensive
inspection of all interceptor assets, or detailed pump station and siphon evaluation. The intent of Phase
1 was to establish a defensible understanding of interceptor configuration and data reliability prior to
defining the scope of a more comprehensive Phase 2 and 3 condition and capacity assessment.
3. Existing Joint Interceptor Agreement
3.1. Parties and Purpose
Based on the most recent Joint Interceptor Agreement, executed in 2003, the City of Ithaca and Town
of Ithaca, together with the Town of Dryden, jointly operate the IAWWTF. The agreement formalizes
the Town of Ithaca’s ownership interests, capacity rights, and cost responsibilities for certain City-
owned sewer interceptors and pump stations used to convey Town wastewater through the City to the
IAWWTF. The agreement replaced interim arrangements established under the 1992 Sewer Service
Agreement and reflects infrastructure constructed between 1991 and 2003.
3.2. Infrastructure Covered
The agreement encompasses a comprehensive network of interceptor sewers and pump stations
serving the West End, Inlet Island, North Side, East Hill, South Hill, and related service areas. These
facilities include:
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Ithaca Sanitary Sewer Joint Interceptor Study
• Jointly owned interceptor sewers that were constructed prior to 2003, which form the basis for the
Town’s ownership interest;
• Existing City interceptors jointly used on a permanent basis to transmit Town wastewater to the
IAWWTF;
• Interceptors that reverted back to full City ownership upon completion of primary interceptor
improvements;
• Proposed future interceptor projects at the time of the 2003 agreement, including a new First Street
Interceptor intended to integrate East Hill and South Hill systems; and
• Pump stations used during normal operations and during periods of high flow or diversion from
primary interceptor routes.
3.3. Ownership Structure and Transition Points
• Ownership and responsibility under the Intermunicipal Agreement (IMA) do not transfer at the
Town–City municipal boundary. Rather, the IMA defines ownership based on designated
interceptor segments, pump stations, and associated facilities identified by specific structures,
regardless of whether those facilities are located within the City or Town. Accordingly, the upstream
limits of the interceptors are established by the structures identified in the IMA and do not
automatically coincide with the Town/City line. The Town of Ithaca owns a 41.57% interest in
designated interceptor sewers and in certain pump stations that provide continuous conveyance of
Town wastewater to the IAWWTF.
• For other pump stations used only during high-flow or emergency conditions, the Town holds a
temporary 17% interest, which may be relinquished as new interceptor capacity is constructed.
• Certain interceptor segments identified in the agreement were temporary joint facilities reverted
back to full City ownership once replacement or primary interceptors were completed.
Accordingly, the functional transition point is facility-based, not jurisdictional, and is tied to system
capacity and operational need, rather than to the Town–City boundary.
3.4. Metering and Flow Monitoring
Flow monitoring and metering are integral to the agreement and are used to track Town wastewater
conveyed through the City system.
• Flow monitoring stations are generally located near the City–Town boundary or at strategic upstream
locations within the interceptor system.
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Ithaca Sanitary Sewer Joint Interceptor Study
• The monitoring stations are components of the jointly owned system as assigned under the Joint
Sewer Agreement (JSA). These facilities are not assumed to be part of the interceptor infrastructure
solely by virtue of their function or location.
Metering is therefore intended to be used for capacity allocation, planning, and cost-sharing, rather
than as a strict ownership demarcation point.
3.5. Financial Terms
At the time of the 2003 agreement, the Town of Ithaca paid $661,000 to acquire its ownership and
capacity interests, funded from existing Sewer System Benefitted Area resources. The Town is
responsible for its proportional share of operation, maintenance, repair, and replacement costs based
on ownership percentages.
3.6. Governance and Legal Framework
The Joint Interceptor Agreement was authorized by resolutions of both the City of Ithaca Common
Council and the Town of Ithaca Town Board in December 2003. The agreement is governed by New
York State law, with venue in Tompkins County, and establishes procedures for amendment, capital
project approval, and dispute resolution.
4. Existing Data Collection and Evaluation
4.1. Data Sources Received
The primary source of information received was the City of Ithaca’s GIS mapping, which contains
multiple layers related to the sanitary sewer system. These layers provided a comprehensive spatial
and attribute framework for understanding system configuration, connectivity, and operational history.
The GIS layers received include:
• Sewer Facility: Locations and attributes of pump stations.
• Sewer Manhole: Manhole locations and attributes, including photographs and rim and invert
elevations, where available.
• Sewer Main: Gravity, force main and siphon sewer alignments, including pipe diameters and
materials.
• Sewer Main Shared Interceptor: GIS representation of jointly owned interceptor mains.
• Sewer Maintenance: Historical maintenance such as flushing and root control.
• Sewer Events: Operational events, such as overflows, blockages, and repairs.
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Ithaca Sanitary Sewer Joint Interceptor Study
• Map Links: References to associated record drawings and additional documentation.
Town GIS data was also available but was used solely to confirm system configurations at connection
points between the Town and the City systems, and to verify the locations of boundary meters where
those meters are situated within the Town.
In addition to the GIS dataset, the City provided supplemental documentation used to refine and
validate the joint interceptor systems. This included:
• Design Plans: Utility improvement plan and profiles from the year 2000 to present (including work
on Aurora Street, Renzetti Place, State Street, and Thurston Ave)
• Historical Sewer Maps: Drawings for infrastructure installed prior to ~1920s showing sanitary sewer
plans, and in some cases profiles and lateral connections. Diameter and material of mains are
listed on some of these maps.
• Old Sewer Maps: Set of maps that is generally the same as the ‘Historical Sewer Maps’, except
that the mapping was redrawn and, in many cases, includes additional information, such as
updated lateral information, small sewer main extensions, and notes from sewer repairs or
installation of new laterals. This set of maps generally supersedes the ‘Historical Sewer Maps’ map
set, but in some cases, the older ‘Historical Sewer Maps’ map set includes additional information
that was not carried forward to the redrawn ‘Old Sewer Maps’ set.
• New Sewer Maps: Set of maps that in most areas only includes plans and not profiles. Content of
this map set also varies, but in many cases includes main diameter and material and
locations/sketches of sewer laterals. This is a newer map set that generally documents newer
sections of City sanitary sewer infrastructure west of the Inlet and around the outskirts of the City,
vs. the Historic/Old Sewer Maps, which typically cover the core of the City.
4.2. Data Evaluation
Following receipt of the City GIS and supplemental documentation, a review and reconciliation process
was completed. The City GIS mapping was compared with design plans for recent sewer installations
and repairs, as well as historical sewer mapping records, to identify discrepancies in alignment,
connectivity, and associated attribute information. Recent design plans were considered to be the most
reliable data source and were used to update interceptor alignments where conflicts existed between
datasets. Additional adjustments were made where newer mapping information superseded older
mapping or generalized GIS representations.
Through this process, the GIS dataset was refined to represent the best available interpretation of
existing system conditions prior to field verification. Overall, the comparison indicated a high level of
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Ithaca Sanitary Sewer Joint Interceptor Study
consistency between the interceptor routes as represented in the City GIS and the supporting design
and mapping documents. The data review also evaluated the completeness of existing survey
information available within the City GIS database. Of the 636 manholes located along the interceptor
system, surveyed rim elevations were already available for 607 structures (95%), while surveyed invert
elevations had previously been collected for 166 interceptor manholes (26%). This existing information
was incorporated into the project database and will be used to reduce the extent of additional field
surveying required during subsequent project phases.
5. Field Investigation
5.1. Field Investigation
Field investigations were conducted to verify/correct assumed interceptor flow paths. As part of the
Phase 1 effort, a total of 96 manholes were inspected. While the original Phase 1 scope included
inspection of 75 manholes, the presence of previously unknown overflow structures and associated
potential lightly shared interceptors required additional inspections. Figure 2 illustrates the locations of
all inspected manholes. Inspection efforts were focused on areas critical to confirming interceptor
routing, as well as locations where uncertainty exists in the current GIS mapping.
Selection criteria included:
• Intersections/convergence points of assumed interceptor flow paths
• Areas of uncertain interceptor routing or connectivity
• Locations suspected to contain overflow piping or weir structures
• All boundary meter and flow monitoring locations
Within GIS, an investigation field was created and standardized system of attributes were documented
during field inspections at each selected manhole location. Recorded field attributes included the date
of inspection, presence of a manhole cone, riser type, riser height, manhole diameter, manhole
material, manhole condition, evidence of infiltration, evidence of surcharge, presence of an overflow
structure, and number of laterals. Pipe inverts were also measured and documented, with the
downstream pipe oriented at the 12 o’clock position and all upstream pipes identified and numbered in
a clockwise direction. Photographs were taken at each inspected manhole, oriented facing north.
An investigation field was also created for each sewer main. Attributes included whether the segment
was identified as a shared interceptor, lightly shared interceptor, interceptor added to mapping, non-
interceptor removed from mapping, flagged for further evaluation, or not planned for investigation.
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Ithaca Sanitary Sewer Joint Interceptor Study
5.2. Findings
Field investigation findings indicate interceptor flow paths are generally consistent with available City
GIS mapping. However, several discrepancies were identified. These include facilities that function as
interceptors that were not previously designated as such (i.e., shared or lightly shared interceptors
added to mapping), as well as facilities previously assumed to be interceptors that may not serve that
function (i.e., non-interceptors removed from mapping). Figure 3 presents the locations of all identified
interceptor revisions. Table 5.2.1 and Table 5.2.2 summarize all interceptor revisions identified during
the investigation. Colors shown in the table correspond to those used in Figure 3.
Shared and Lightly Shared Interceptors Added to Mapping
Lightly shared interceptors added to mapping were identified in areas where overflow structures had
not been previously documented. These overflow structures allow a portion of the flow from jointly
owned interceptors to spill over into the lightly shared interceptors when/if flow elevations exceed the
overflow structure flow control elevation. All identified overflow structures are shown in Figure 4. While
LDG's assessment suggests these facilities may function as lightly shared interceptors, confirmation of
their classification should be made jointly by the City and Town. Accordingly, these segments are
presented as lightly shared interceptors pending municipal review and final designation. Capacity
calculations anticipated to be completed during Phases 2 and 3 of the Interceptor Study may indicate
that some of the lightly shared interceptors, although connected to the interceptor system through
overflow structures, do not convey flow under expected operating conditions. If the primary interceptor
trunk lines have sufficient capacity to convey all Town and City flows without activating these overflow
connections, the lightly shared segments may not function as interceptor facilities and, therefore, may
not warrant classification as interceptor runs.
Shared interceptors added to mapping were identified in two locations: within Cass Park and near
Boynton Middle School. In both areas, City GIS mapping indicated that the interceptor terminated short
of the Town/City boundary. At Cass Park, the interceptor alignment was confirmed through dye testing.
This effort also led to the identification of a clogged line, which was subsequently flushed by City
maintenance staff during the inspection, allowing the alignment to be verified. LDG believes that in both
locations, the Interceptor runs extend to the Town/City boundary.
As shown in Table 5.2.1, some pipe segments were also identified for further evaluation. The Sisson
Place Interceptor is currently identified as terminating at MH #938. However, multiple upstream pipe
segments are depicted before the system enters Cornell University. The appropriate upstream extent
of the Sisson Place Interceptor should be reviewed and established through coordination between the
City and Town.
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Ithaca Sanitary Sewer Joint Interceptor Study
Additionally, two pipe runs along Haller Boulevard follow the Town/City boundary and receive flow from
both service areas. Because these segments have shared tributary areas, their classification as
interceptor runs was evaluated. Following discussions with the Town and City, it was determined that
these segments receive minimal Town flow and should not be classified as interceptors. Therefore, no
revisions were made to the interceptor mapping and these segment are not noted in the report tables.
Table 5.2.1: Shared and Lightly Shared Interceptors Added to Mapping
Location Pipe Run
Existing City
Mapping
Designation
LDG Recommendations
Intersection of Mitchell St. / Ithaca Rd. to
Intersection of Valley Rd. / East State St. MH1546 to MH1765 Non-Interceptor Lightly Shared
Interceptor
East State St. MH1114 to MH1210 Non-Interceptor Lightly Shared
Interceptor
East State St. MH1673 to MH1672 Non-Interceptor Lightly Shared
Interceptor
South Aurora St. MH957 to MH891 Non-Interceptor Lightly Shared
Interceptor
Intersection of Columbia St. / South
Aurora St. to Intersection of South
Cayuga St. / West Green St.
MH370 to MH1763 Non-Interceptor Lightly Shared
Interceptor
Intersection of East Court St. / North
Aurora St. to Intersection of North Plain
St. / West Court St.
MH1099 to MH533 Non-Interceptor Lightly Shared
Interceptor
Intersection of Elm St. / Chestnut St. to
Floral Ave.
MH1836 to MH3
(Siphon Structure) Non-Interceptor Lightly Shared
Interceptor
Cass Park Route 89-10 MH to
MH1470 Non-Interceptor Shared Interceptor
State Route 13 (Near Boynton Middle
School)
East Shore BL 15 MH
to MH2339 *Non-Interceptor Shared Interceptor
Sisson PI MH 940 to MH 2660 Shared-Interceptor Shared Interceptor
*Existing city mapping identified three pipe segments from East Shore BL 15 MH to MH2339 as shared
interceptors, however the majority of the pipe run was identified as non-interceptor
Non- Interceptors Removed from Mapping
Several sanitary sewer segments were identified in areas where City GIS mapping indicated interceptor
infrastructure extended beyond the City limits into the Town. Unless otherwise specified in the
Intermunicipal Agreement (IMA), jointly owned interceptors are assumed to begin at the manholes
nearest to the Town/City boundary.
One previously mapped interceptor that was determined to be a non-interceptor was identified on East
State Street, where an overflow structure previously located at MH64 is no longer present. An additional
previously mapped interceptor that was determined to be a non-interceptor was identified in downtown
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Ithaca Sanitary Sewer Joint Interceptor Study
Ithaca. Field observations indicate that all flow entering MH1240 is conveyed southwest to MH1241.
Based on these observed flow patterns, the sewer segments extending upstream to the northeast do
not appear to function as shared interceptor sewer infrastructure.
It was observed in multiple locations along Thurston Ave that interceptor flow has been rerouted to
more recently installed sewer mains. As a result, the previously abandoned or removed sewer main
segments are not believed to function as interceptors and are therefore considered non-interceptors
pending municipal review and final designation.
Table 5.2.2: Non-Interceptors Removed from Mapping
Location Pipe Run
Existing City
Mapping
Designation
LDG Recommendations
Trumansburg Rd. near Town / City line MH1484 to MH1418 Shared Interceptor Non-Interceptor
Mecklenburg Rd. near Town / City line Near MH1343 to
MH1339 Shared Interceptor Non-Interceptor
Elm St. near Town / City line Near Elm St. Ext. 20
MH to MH1296 Shared Interceptor Non-Interceptor
Five Mile Dr. near Town / City line Near MH1416 and
MH1415 to MH343 Shared Interceptor Non-Interceptor
South Aurora St. near Town / City line Danby 03 MH to
MH57 Shared Interceptor Non-Interceptor
Coddington Rd. near Town / City line Near MH336 to
MH335 Shared Interceptor Non-Interceptor
South Hill Recreation Way at Coddington
Rd. near Town / City line
Near Coddington BL
20 MH to MH67 Shared Interceptor Non-Interceptor
South Hill Recreation Way at Pearsall PI
near Town / City line
MH191 to South 10
MH Shared Interceptor Non-Interceptor
East State St. near Town / City line Near MH1115 to
MH1675 Shared Interceptor Non-Interceptor
Mitchell St. near Town / City line MH992 to MH2234 Shared Interceptor Non-Interceptor
East State St. MH64 to MH1765 Shared Interceptor Non-Interceptor
Intersection of Hancock St. / 4th St. to
Intersection of 1st St. / Adams St. MH1240 to MH700 Shared Interceptor Non-Interceptor
Thurston Ave MH2663 to MH1080 Shared Interceptor Non-Interceptor
Thurston Ave MH1074 to MH2665 Shared Interceptor Non-Interceptor
Thurston Ave MH2649 to MH2653 Shared Interceptor Non-Interceptor
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Ithaca Sanitary Sewer Joint Interceptor Study
Additional Interceptor System Components
During the field investigation, several interceptor system components were verified (Figure 5),
including:
• Three siphons: Cayuga Inlet near Buffalo Street Bridge, Cayuga Inlet near Cecil Malone Drive,
and Sixmile Creek near Taughannock Boulevard
• Four pump stations with associated force mains: Cass Park, Stewart Park #2, Cherry Street,
and Giles Street
• Nine aerial water crossings
6. GIS Database Development
Following completion of field verification, the GIS database was updated to incorporate all reconciled
data sources and field findings. This included integrating City GIS information, supplemental design
and mapping records, and field-verified corrections into a single consolidated geodatabase. As a result
of this process, an updated joint interceptor network was developed, as shown in Figure 6.
Using GIS, an office follow-up field was created for each manhole and sewer main. For both asset
types, the field included a comparison to the City’s assumed interceptor network to indicate whether
the asset remained the same or was added or removed as an interceptor.
For manholes, the field also identified whether the asset was a shared interceptor, lightly shared
interceptor, interceptor added to mapping, non-interceptor removed from mapping, flagged for further
evaluation, or not planned for investigation. For sewer mains, the field identified whether the asset was
a gravity main, force main, aerial water crossing, gravity water crossing, or siphon.
7. Phase 2 and 3 Recommendations
Phases 2 and 3 will build upon the findings of Phase 1 and focus on completing a more detailed
condition assessment, targeted field data collection, and hydraulic capacity evaluation of the interceptor
system. The focus will shift from data validation to system performance assessment under existing flow
conditions.
7.1. Overview and Approach
Phase 2 will include collection of additional field and operational data necessary to support hydraulic
capacity calculations and capacity evaluation, confirmation and refinement of system configuration, and
flow metering to confirm the accuracy of boundary meters and the four main trunk lines entering the
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Ithaca Sanitary Sewer Joint Interceptor Study
WWTP. Phase 3 will include assessment of pump station and siphon interceptor assets not evaluated
during Phases 1 and 2, and intermittent flow metering along interceptor routes. The overall approach
will emphasize efficient use of available data and prioritization of field efforts based on identified data
gaps and system needs.
7.2. Manhole Data Collection and Verification
Field efforts will include verification and inspection of interceptor manholes not included in Phase 1.
Data collection is anticipated to include manhole condition assessments, photographic documentation,
and measurement of depths from rim to pipe inverts, as necessary to support hydraulic evaluation.
City GIS data was found to be more complete than initially anticipated. As a result, a comprehensive
survey of manhole rim elevations is not required. 27 manholes were found to not have survey data for
rims, and that information will be collected by Town staff. A targeted approach to field verify and
supplement existing elevation and invert data will be performed, focusing on locations where data gaps
or uncertainties exist. 470 manholes were found to be missing invert data, and they will be inspected
in Phase 2.
A GIS-based field data collection application will be utilized to facilitate real-time integration of
inspection data and photographs into the interceptor system database.
Figures 9 and 10 summarize the interceptor system data currently available to support Phase 2
evaluations. Figure 9 identifies manholes with photographic documentation, while Figure 10 identifies
manholes with available rim and invert elevation information. These datasets will be used to help guide
targeted field verification efforts and help identify locations where additional data collection may be
necessary.
7.3. Pump Station and Siphon Evaluation
Pump stations and siphons identified in Phase 1 as components of the interceptor system will be
evaluated to assess their condition, performance, and hydraulic capacity as part of Phase 3. Based on
Phase 1 findings, the interceptor system includes 3 siphons and 4 pump stations.
The evaluation will begin with a coordination meeting with City and Town staff to review available
information and discuss known operational concerns. Available data to be collected and reviewed will
include record drawings, equipment data (e.g., nameplate information and pump curves), and
operational and energy usage records (e.g., pump run times and 12-month electrical consumption).
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Ithaca Sanitary Sewer Joint Interceptor Study
Field evaluations of pump stations will include visual inspection and documentation of major accessible
components, including photographic records. In addition, basic pump performance testing will be
conducted, where feasible, by observing fill and drawdown cycles and correlating level changes with
pump operation. Where instrumentation is available, discharge pressure data may also be reviewed.
These efforts will be used to estimate current pump operating conditions and identify potential
inefficiencies or operational constraints.
A corresponding desktop analysis will be performed for each pump station, incorporating field
observations and available system data. This analysis will include development of system curves for
associated force mains, review of pump performance relative to available pump curves, and evaluation
of overall system operation. Energy usage trends will be summarized, and major electrical loads will be
identified. Based on this assessment, opportunities for operational improvements, controls optimization,
energy conservation, and capital upgrades will be identified, including both low-cost measures and
longer-term improvements.
Partial siphon evaluation was completed during Phase 1 as part of targeted field verification; however,
additional evaluation will be completed in Phase 3. A desktop hydraulic assessment will be conducted
based on available record information to estimate system capacity and evaluate performance. Any
available prior inspection data, such as CCTV records, will be reviewed where available.
The overall assessment will identify current condition, operational considerations, capacity, and
maintenance needs for each facility, and will provide recommendations for system improvements or
rehabilitation where warranted.
7.4. Temporary Flow Metering Program
A temporary flow metering program will be implemented to support evaluation of interceptor capacity
and system performance under both dry and wet weather conditions. This effort will be performed in
coordination with a subconsultant experienced in temporary flow monitoring.
Battery-powered, area-velocity flow meters will be utilized to collect flow data at selected locations
throughout the interceptor system. The subconsultant will be responsible for installation, calibration,
data collection, and removal of the monitoring equipment.
Phase 2
Monitoring to be performed in Phase 2 will focus on verification and calibration of existing boundary
flow meters located at the interface where the Town collection system discharges to the interceptor
system. Temporary meters will be installed downstream of these locations to confirm the accuracy and
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Ithaca Sanitary Sewer Joint Interceptor Study
reliability of permanent meter data. This step is intended to ensure that boundary flow data can be
confidently used in subsequent system-wide analyses and comparisons. Within the same timeframe as
the boundary meter verification, the City of Ithaca will be working on a Preliminary Inflow and Infiltration
(PII) study of their own system. The City plans to install four (4) temporary meters on main interceptor
lines entering the WWTP. It is anticipated that this data will be made available for comparison to
boundary meter flows.
Figure 7 illustrates the locations of the existing boundary meters. These meters are operated and
maintained by Lectre under contract with the City of Ithaca. The minimum, maximum, and average
values presented in Figure 7 were extracted from Lector’s data logging system. At the time of review,
only the most recent three months of historical data were available, and the values presented reflect
conditions during that monitoring period, from January 11, 2026, through March 12, 2026.
Phase 3
Following verification of existing boundary meters, additional temporary flow metering locations, as
shown in Figure 11, will be established throughout the interceptor system to support capacity evaluation
in Phase 3. The number and placement of these locations have been refined based on Phase 1 findings
and it is anticipated that approximately 25 total monitoring locations will be required. Rather than
deploying meters at all locations simultaneously, the monitoring program may be completed in two
consecutive one-month monitoring periods. Approximately 12-13 flow meters will be deployed during
each monitoring period and subsequently relocated to the remaining monitoring locations, allowing all
25 locations to be monitored while significantly reducing equipment requirements.
Each temporary monitoring location is expected to collect a minimum of one month of continuous flow
dataMonitoring will be scheduled to occur while both Ithaca College and Cornell University are in
session to ensure that collected data reflect typical population conditions, including student occupancy
within the service area.
7.5. Data Analysis and Capacity Evaluation
Collected flow data will be analyzed to quantify average dry weather flows and peak wet weather
responses throughout the interceptor system. Measured flows will be compared to calculated pipe
capacities to evaluate system performance.
The analysis will include assessment of flow contributions between metered segments and comparison
of interceptor flows with influent data at the treatment facility. This effort will support identification of
capacity limitations and system bottlenecks. Interceptor pipe sizes are a key input to this capacity
evaluation. Interceptor pipe sizing is presented in Figure 8. As discussed in Section 5.2 of this report,
Page 15 of 15
Ithaca Sanitary Sewer Joint Interceptor Study
the capacity analysis will also be used to evaluate whether the identified overflow structures convey
flow from the Town. The results of this analysis will help determine whether the associated overflow
segments function as lightly shared interceptor infrastructure. The majority of this work would occur in
Phase 2, and areas of concern that are identified would be considered points of interest for Phase 3
flow metering. Phase 3 metering results would be used to further enhance the capacity analysis of the
interceptor systems.
7.6. System Evaluation and Recommendations
Based on the results of field investigations and data analysis, deficiencies in interceptor capacity and
asset condition will be identified. Recommendations will be developed for operational improvements,
maintenance actions, and capital upgrades, including potential pipe upsizing where warranted.
Areas requiring additional study, particularly in advance of future development, will also be identified.
7.7. Reporting
A comprehensive technical report will be prepared documenting the methodology, assumptions, field
data collection, analysis results, system evaluation, and recommended improvements. Phase 2 and 3
findings will be integrated with Phase 1 into a single consolidated report.
Figures
1 West Market Street, Suite 301, Corning, NY 14830
607.936.7076 | larsondesigngroup.com
August 7, 2026
Justin McNeal– Director of Engineering/Town Engineer
Town of Ithaca
Engineering Department
114 Seven Mile Drive
Ithaca, NY 14850
Re: Scope and Fee Proposal
Town of Ithaca and City of Ithaca Sanitary Sewer Joint Interceptors Study, Phase 2
Dear Justin,
LDG is pleased to submit this proposal for professional engineering services for Phase 2 of the Town of
Ithaca and City of Ithaca Sanitary Sewer Joint Interceptors Study.
BACKGROUND
The Town of Ithaca (Town) and the City of Ithaca (City) completed Phase 1 of a study of the sanitary sewer
interceptor infrastructure jointly owned by the City and the Town.
As part of Phase 1 of the study of the sanitary sewer interceptor infrastructure jointly owned by the City and
the Town, LDG conducted a preliminary evaluation of gravity collection infrastructure, including manholes
and gravity main runs to confirm the status of the interceptor runs. This work included collecting and
reviewing all available data, including City GIS mapping and as-builts, and conducting a limited field
evaluation of manholes to provide a sampling of manhole condition assessments and to help identify areas
where flow direction and interceptor orientation was unclear based on provided data. As part of the Phase
1 effort, a total of 96 manholes were inspected. Dye testing was performed on an as-needed basis to help
confirm interceptor routes.
LDG provided a report of our findings on data collection, preliminary system analysis, and dye testing. The
report made recommendations for additional field data collection and suggested the quantity, location, and
duration of flow metering needed to conduct a gravity collection asset capacity assessment in following
phases of the study.
It is understood that the primary goals of this study are:
• To evaluate the general condition of the jointly owned sanitary sewer interceptor infrastructure to:
o Understand and plan for future capital improvements needed for this infrastructure.
o Identify operational improvements that may extend or improve the functionality and lifespan
of these assets.
• To gauge the existing capacity of the jointly owned sanitary sewer interceptor infrastructure to
support planning for future improvement and future development.
• Confirm/verify or calibrate the permanent boundary meters at the Town/City border locations where
the Town collection system discharges to the interceptor sewer.
August 7, 2026
Scope and Fee Proposal
Phases 2 - Sanitary Sewer Joint Interceptors Study
Page 2
SCOPE OF SERVICES FOR PHASE 2
Phase 2 of this study will include extensive manhole field data collection, including opening manholes to
perform manhole inspections and measure pipe inverts, temporary flow metering, capacity analysis, and
reporting and presentation.
A future Phase 3 will include additional intermittent flow metering, comparison of flow metering results to
pipe capacities calculated in Phase 2, evaluation of all pump station and siphon assets, and reporting and
presentation.
Task 2A: Manhole Inspections and Invert Collection
As noted above, precise measurements of rim elevation to pipe invert are required to accurately calculate.
Data collection will include:
1. Locate and open each manhole (traffic control to be provided by Town or City staff).
2. Inspect each manhole and collect manhole inspection information and photographs.
3. Measure and record dept from rim to inverts of all pipes.
It is expected that the GIS-based field inspection application utilized in Phase 1 will be utilized again to
allow field inspection data and photographs to be linked to the interceptor GIS database in real time. The
result will be a complete GIS database of the Interceptor runs.
Estimated pricing for this task is based on a 2-person LDG field crew completing this investigation on 470
manholes. This number of manholes requiring further inspection were identified in Phase 1 by using the
City’s GIS data to determine which manholes were missing invert and pipe invert information.
Task 2B: System Capacity Analysis
Data collected under Task 2A will be utilized in sewer capacity calculations. LDG will perform basic pipe
capacity calculations for the interceptor systems within the field GIS data collection system. Pipe material,
diameter, upstream elevation, and downstream elevation, will be used to calculate the theoretical maximum
flow capacity for each individual gravity pipe run.
Task 2C: Temporary Flow Metering
LDG will utilize a subconsultant to provide temporary flow metering at various locations across the
interceptor sewers. Subconsultant will utilize battery-powered temporary area-velocity meters to collect flow
data at each selected location. The units will be installed, calibrated, data collected and removed by the
subconsultant. Each temporary monitoring location is expected to collect a minimum of one month of
continuous flow data. Monitoring will be scheduled to occur while both Ithaca College and Cornell University
are in session to ensure that collected data reflects typical population conditions, including student
occupancy within the service area.
The Phase 2 stage of flow metering will involve installing temporary flow metering downstream of each of
the 13 boundary flow meter stations where the Town collection system discharges to the interceptor sewer.
These temporary meters will be used to confirm/verify or calibrate the permanent boundary meters so that
the boundary meter flow data quality can be confirmed and so that flow meter data collected at the boundary
meter sites can be utilized for data comparison with subsequent downstream temporary metering locations
August 7, 2026
Scope and Fee Proposal
Phases 2 - Sanitary Sewer Joint Interceptors Study
Page 3
included in the capacity evaluation. Location for flow monitoring will be reviewed and coordinated with the
Town/City of Ithaca prior to installation.
Within the same timeframe as the boundary meter verification, the City of Ithaca will be working on a
Preliminary Inflow and Infiltration (PII) study of their own system. The City plans to install four (4) temporary
meters on main interceptor lines entering the WWTP. It is anticipated that this data will be made available
for comparison to boundary meter flows.
Based on observed flows and the capacity analysis described in Task 2B, a preliminary high-level capacity
analysis comparing hydraulic capacities to metered flows will be conducted (Task 2D) and
recommendations will be made for quantities and locations of intermittent flow metering locations for Phase
3. As this time, it is estimated that a total of 42 flow metering locations will be utilized for the capacity
evaluation by utilizing 13 boundary meters in Phase 2, the 4 meters included in the City’s PII study, and
approximately 25 meters that will be installed along interceptor runs in Phase 3.
Task 2D: Data Analysis:
Flow meter data will be received and reviewed by LDG to assess current interceptor segment flows. The
data analysis exercise will include subtracting upstream flow metering data to calculate flow attributed to
collection system areas located between 2 meter locations. It is also expected that the City will provide
influent flow metering data for measured flow into the treatment facility, along with meter results from their
PII study, and that these data sets will also be analyzed and compared with the temporary flow metering
data.
Task 2E: Reporting
LDG will provide a report of our findings based on the manhole data collection, capacity analysis, and flow
metering results. It is expected that the additional reporting generated from Phase 2 of the study will be
added to the Phase 1 reported to generate a single, updated report that describes both Phases of the study.
The report will include methodology, findings, system deficiencies, recommended improvements and
assumptions.
LDG will provide recommendations for potential upsizing where calculations indicate undersized pipe runs
and identify areas where additional intermittent metering should be performed in Phase 3 to further enhance
the capacity analysis of the interceptor systems.
Task 2F: Progress Meetings and Presentation
1. LDG will attend one (1) in-person progress meeting and two (2) virtual progress meetings to review
project status with the Client, identify potential issues, and ensure alignment of project goals and
next steps. These meetings are in addition to the meetings included in Phase 1.
August 7, 2026
Scope and Fee Proposal
Phases 2 - Sanitary Sewer Joint Interceptors Study
Page 4
PHASE 2 FEE
LDG proposes completing the Phase 2 scope of services described herein for a lump sum fee of $144,450
including reimbursable expenses, broken down on a per-task basis as follows:
Task Lump Sum
Task 2A: Manhole Inspections and Invert Collection $47,000
Task 2B: System Capacity Analysis $8,200
Task 2C: Temporary Flow Metering $64,000
Task 2D: Data Analysis $6,500
Task 2E: Reporting $12,000
Task 2F: Progress Meetings and Presentation $3,500
Reimbursable Expenses $3,250
Total $144,450
SCHEDULE
It is anticipated that all Phase 2 services can be completed within 8 months of notice to proceed, assuming
Town and City can have staff readily available for meetings and field visits. It is assumed that temporary
flow meter data collection will be completed in the Fall of 2026.
PHASE 3
A detailed scope and fee for Phase 3 will be developed as Phase 2 progresses and informs the need for
additional flow data collection. Phase 3 is currently anticipated to include additional flow metering and
associated data analysis and reporting to complete a more detailed capacity analysis. Phase 3 is also
anticipated to include a condition and capacity analysis of all pump stations and siphons included in the
interceptor sewer network.
CLOSING
LDG looks forward to another opportunity to assist the Town with your wastewater infrastructure needs. If
you have any questions, please feel free to contact me at LDG’s Corning office at (607) 463-2903 or by
email at bsick@larsondesigngroup.com.
Sincerely,
LARSON DESIGN GROUP
Brad Sick, PE
Project Manager
Cc: Joe Slater, Highway Superintendent / Director of Public Works [via jslater@townithacany.gov]