ansonia derby interconnection feasiblity study - compiled document
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City of Derby, CONNECTICUT
Water Pollution Control
Authority
Ansonia Derby Interconnection
Feasibility Study
Mr. John Saccu, Chairman
Mr. Lindsay King, WPCF Superintendent
Water Pollution Control AuthorityMr. Richard Bartholomew Mr. Robert Miani
Ms. Carolyn Duhaime Mr. James Gildea
Ms. Marcy McGuire, Administrator
April 2014
Weston & Sampson Engineers, Inc.
273 Dividend RoadRocky Hill, CT 06067
www.westonandsampson.comTel: 860-513-1473
Fax: 860-513-1483
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City of Derby, Connecticut
Derby-Ansonia Feasibility Study ii
April 2014
LIST OF FIGURES
Figure 2-1A Ansonia-Derby Interconnection Force Main
Figure 2-1B Ansonia-Derby Interconnection Force Main
Figure 2-2A Ansonia-Derby Interconnection Force Main
Figure 2-2B Ansonia-Derby Interconnection WWTF Upgrades
Figure 2-3 Ansonia-Derby Interconnection East Derby Pump Station
LIST OF APPENDICES
Appendix A Regionalization Letters
Appendix B Ansonia WPCF – UV Hydrualic Failure Information
Appendix C Storage Analysis Data and Results
Appendix D Ansonia-Derby Interconnection Opinion of Probable Costs
Appendix E Ansonia Interconnection Alternatives – UIC Reports
Appendix F Ansonia – Derby Interconnection Meeting Minutes 3-12-2012
Appendix G Ansonia – Derby DEEP Interconnection Meeting Minutes 10-15-2012
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interconnect with the Derby WPCA collection system via an 8-inch forcemain connection but the
allowable pumping rate shall not exceed 800 gpm.
1.3 Regionalization with the Town of Woodbridge
The Town of Woodbridge has expressed no interest in regionalization with the Derby WPCA.
The town is currently a member community of the Greater New Haven Water Pollution Control
Authority. As a member of the GNHWPCA, the town’s wastewater is treated at the East Shore
Water Pollution Control Facility located in the City of New Haven. As such, no flow allocation
has been provided for the Town of Woodbridge.
1.4 Regionalization with the City of Shelton
The City of Shelton recently completed a major upgrade and capacity expansion to its WPCF
and does not have capacity issues within its system. The Derby WPCA expressed an interest in
connecting to the City of Shelton collection system for wastewater treatment and disposal since
the two WPCF sites are located on opposite sides of the Housatonic River at the Route 8
crossing (Commodore Isaac Hull Memorial Bridge). The City of Shelton has indicated on
several occasions that it is not interested in receiving and treating flows from the Derby WPCA
at the City of Shelton WPCF.
1.5 Regionalization with City of Ansonia
The City of Ansonia expressed an interest in interconnecting the City of Derby wastewater
collection system for wastewater treatment and disposal at the Ansonia WPCF since the two
WPCF sites are located approximately 1.5 miles from each other along the Naugatuck River
and the City of Ansonia recently completed a major upgrade of its WPCF, which is permitted for
an annual average flow of 3.5 MGD. Based on the information provided in its 2004 Wastewater
Facilities Plan (prepared by Camp Dresser and McKee) the Ansonia WPCF, is anticipated to
have an annual average flow surplus of approximately 1.3 MGD in 2025, based on the proposed
build out (0.4 MGD). Based on an Analysis Report completed by United International
Corporation (UIC) on behalf of the City of Ansonia, the Ansonia WPCF has a permitted annual
average design capacity of 3.5 MGD and a peak design hydraulic capacity of 12.0 MGD.
Discussions with Ansonia WPCF staff and a review of the failure associated with Module #1 of
the UV system in 2011 indicates a hydraulic bottleneck occurs somewhere between the UV
system and the effluent discharge to the Naugatuck River. Based on a discussion with Ansonia
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City of Derby, Connecticut
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The 20-year build out flows for Ansonia were obtained from information provided within the City
of Ansonia’s 2004 Wastewater Facilities Plan. The information provided in the plan indicates
that additional flows from the City of Derby were neither anticipated nor accounted for as part of
the Wastewater Facilities Plan, nor were additional flows from Derby included in the subsequent
upgrades to the Ansonia WPCF. The combination of the current flows and the 20-year build out
flows are presented in Table 1-2 and Table 1-3.
Table 1-2: Current Flow Conditions Ansonia and Derby combined Flows
Current FlowCondition
AnsoniaFlow (MGD)
Derby Flow(MGD)
Total Flow(MGD)
Ansonia WPCFCapacity (MGD)
Ansonia WWTFExcess Capacity
(MGD)
Annual Average
1.8 1.6 3.4 3.5 0.10
Peak Day 10.5 10.0 20.5 7/12 -13/-8.5
Table 1-3: 20-Year Flow Conditions Ansonia and Derby combined Flows
20-Year FlowCondition
AnsoniaFlow (MGD)
Derby Flow(MGD)
Total Flow(MGD)
Ansonia WPCFCapacity (MGD)
Ansonia WWTFExcess Capacity
(MGD)
Annual Average
2.2 2.4 4.6 3.5 -1.10
Peak Day 7.4 9.5 16.9 7/12 -9.9/-4.90
As shown in Table 1-2, the Ansonia WPCF provides adequate capacity to treat the current
combined annual average flows from both communities. However it does not have capacity to
treat the current combined peak flows from both communities. In addition, the information
presented in Table 1-3 indicates that the Ansonia WPCF does not provide adequate capacity to
treat the combined annual average and/or the combined peak flows from both communities
based on the 20-year build out flows presented in each community’s wastewater facilities plan.
In order to facilitate a possible interconnection between the City of Ansonia and the City of
Derby, the following would need to occur:
• Derby would need to aggressively begin removing I/I. In previous reports, Ansonia has
indicated that Derby needs to reduce the annual I/I component to no greater than 0.50
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MGD. This will require the removal of approximately 10 MGD of I/I from the system.
This would require the removal of both cost effective and non-cost effective I/I and may
still not be attainable as the system continues to age.
• Ansonia would need to continue removing I/I. Ansonia has recently completed several
I/I remediation projects. Ansonia would need to continue removing I/I, this would require
the removal of both cost effective and non-cost effective I/I.
• Ansonia would need to upgrade the WPCF to expand capacity. The Ansonia WPCF
does not have adequate capacity for the combined flows from both communities and
would be beyond the statutory 90% flow capacity threshold on an annual average basis
upon completion of the interconnection. Failure to upgrade the WPCF would limit the
growth and economic development in both communities.
• A regional WPCA would need to be created. Each community would relinquish sole
control of its wastewater system. A regional WPCA board comprising members from
each community would be created with each community having an equal say. At a
meeting with CT DEEP, the City of Ansonia has indicated that they are not in favor of a
regional WPCA and that City of Derby would be deemed a paying customer.
1.5.2 Storage Analysis
To determine the storage volume required for the City of Derby, the reported Derby WPCF flow
records for 2011 were analyzed. Using the reported Derby WPCF effluent flows, a requiredstorage volume could be calculated based on a given pumping rate. The required storage
volumes, shown in the Table 1-4, are the result of a two week period in March 2011 during
which three storms occurred. The first storm in March 2011 included an equivalent rainfall of
5.75 inches, which includes snow melt and is slightly higher than a 10-year return interval storm.
Two smaller storms followed within two weeks after the first storm. The results of the storage
analysis are presented below in Table 1-4 and the charts and raw data for the analysis are
included in Appendix C.
Table 1-4: Required Storage Volumes At Various Pumping Rates
Derby PumpingRate (gpm)
Derby PumpingRate (MGD)
Ansonia WPCF PeakCapacity MGD
Storage Volume MG(7 MGD / 12 MGD Capacity)
3,000 4.3 7 / 12 13.1 / 8.1
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Derby PumpingRate (gpm)
Derby PumpingRate (MGD)
Ansonia WPCF PeakCapacity MGD
Storage Volume MG(7 MGD / 12 MGD Capacity)
4,000 5.8 7 / 12 11.5 / 3.5
5,000 7.2 7 / 12 6.8 / 1.8
6,000 8.6 7 / 12 5.72 / 0.72
7,000 10.1 7 / 12 5.0 / 0
Since the Ansonia WPCF can be upgrades to attain its design peak hydraulic design capacity of
12.0 MGD and the 20-year design peak flow for the City of Ansonia is anticipated to be 7.4
MGD, the maximum pumping rate that could be used by the City of Derby is 3,200 gpm or 4.6
MGD. Based on the storage analysis presented in Table 1-4, the City of Derby would be
required to store approximately 8,000,000 gallons (assuming the Ansonia WPCF increases the
hydraulic actual peak capacity to the design of 12 MGD) of raw wastewater for storms similar to
those that occurred in March 2011 or storms greater than the 10-year return interval storm
event. Based on the flows experienced at the Derby WPCF over this time period and the
allowable pumping rate, it would take approximately two weeks to pump all of the stored
wastewater volume to the Ansonia WPCF for treatment. The rainfall amount for a 100-year
return interval storm event is 9.4 inches, which would result in an even greater required storage
volume or a higher pumping rate to prevent a bypass or an overflow.
The interconnection concept is not feasible at this time due to the excessive storage volumes
required (8 to 13 million gallons). The City of Derby has indicated that the interconnection
concept will not be feasible until the required storage volume is reduced to 1 million gallons or
less due to odor concerns as well as operations and maintenance concerns associated with the
storage facility. This can be accomplished by a combination of the following:
• Reduction of I/I from Derby
• Reduction of I/I from Ansonia
• Upgrades and expansion of the Ansonia WPCF
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2. Ansonia Derby Interconnection Alternatives
2.1 Alternative 1 - Elimination of the Derby WPCF with pumping of flows to the Ansonia
WPCF
Alternative 1 diverts flow from the Derby WPCF to the Ansonia WPCF via a new interconnectingpumping station and force main. Based on discussions with the City of Ansonia, the City of
Derby would need to provide fine screening and grit removal before the interconnection
pumping station since it would function as a satellite headworks for the Ansonia WPCF. To
facilitate operations during construction as well as the fine screening and grit removal systems,
the influent pump station at the Derby WPCF would need to be replaced with a new larger
pumping station, this would also allow for the screening and grit removal systems to be provided
before the wastewater pumps . After passing through the screening and grit removal systems
Derby’s wastewater would be pumped directly into the primary settling tanks at the Ansonia
WPCF. Two four-million gallon storage tanks would need to be installed at the Derby WPCF
(See Section 1.5.1) to accommodate peak flows. Conceptual layouts for the pump station and
force main are shown on Figures 2-1A and 2-1B.
The results of the conceptual interconnection analysis were based on an allowable pumping
rate of 3,200 gpm, which was dictated by the City of Ansonia. The City of Ansonia noted that
the flows from the City of Ansonia combined with the pumping rate from the City of Derby could
not exceed the Ansonia WPCF design hydraulic capacity. An upgrade to the Ansonia WPCF
would be needed in order to increase the current hydraulic capacity (7 MGD) to the design
hydraulic capacity (12 MGD). To achieve the required cleansing velocities while reducing the
friction head within allowable values, a 16-inch diameter force main is recommended. Due to
constructability and underground utility corridor issues, the best force main route from the Derby
WPCF to the Ansonia WPCF is approximately 9,000 linear feet. Based on the static head,
allowable pumping rate, pipe diameter and length of the force main, the wastewater pumps
would pump against approximately 75 feet of total dynamic head. Conceptual estimates
indicate that this would require four 100-horsepower variable speed drypit style wastewater
pumps operating in parallel. Each of the pumps would be provided with a dedicated VFD to
allow for flow fluctuations between the normal and the I/I induced peak flows. To prevent
overflows during events greater than the 10-year storm, Derby will either have to pump at rates
higher than 3,200 gpm or provide greater than 8 million gallons of storage. As previously noted,
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The preliminary opinion of probable costs for interconnection with the City of Ansonia is
approximately $50,000,000 which includes design and a planning level contingency. A
breakdown of the project costs is included in Appendix D. NOTEWELL: The opinion of
probable costs does not include any upgrades to expand the permitted capacity of the Ansonia
WPCF or any of the costs associated with the removal I/I.
If the WPCA were to proceed with the Interconnection, the WPCA estimates that the annual
cost of maintaining the collection system and wastewater pumping stations is $1,860,000. This
annual cost does not include any existing or future capital debt service or wastewater disposal
fees to the City of Ansonia.
2.3 Alternative 3 - Elimination of the Derby WPCF with pumping of flows between the
Ansonia WPCF and Shelton WPCF
As noted in Section 1.4 the City of Shelton has expressed no interest in regionalization with the
City of Derby. The City of Shelton recently completed a major upgrade and capacity expansion
to its WPCF and does not have capacity issues within its system. The City of Derby expressed
an interest in interconnecting with the City of Shelton for wastewater treatment and disposal at
the Shelton WPCF. The City of Shelton and the City of Derby WPCF sites are located on
opposite sides of the Housatonic River at its intersection with Route 8. The City of Shelton has
noted on numerous occasions that it is not interested in receiving and treating flows from the
City of Derby.
Since the City of Shelton is not interested in interconnecting with the City of Derby this
alternative is not viable and was eliminated from consideration.
2.4 Alternative 4 – Alternatives Presented by the City of Ansonia
The following Interconnection alternatives were presented to the City of Derby by the City of
Ansonia through a study conducted by United International Corporation (UIC – now Prime
Engineering). Additional Interconnection Alternatives were also discussed in detail by Ansonia
Mayor James Della Volpe in a press release from September 2013 during his re-election
campaign. A copy of the press release and alternatives are provided in Appendix E.
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2.4.1 Option 1 – Storage at Derby WPCF and Off-Peak Pumping to Ansonia
Under Option #1, which was prepared and proposed by UIC on behalf of the City of Ansonia,
the City of Derby would utilize the existing WPCF for preliminary and primary treatment and the
storage of up to 2.0 million gallons of wastewater per day. The storage volume would
encompass the total volume of the City of Derby WPCF aeration basins and secondary
clarifiers. The wastewater would be pumped to the Ansonia WPCF via a 6-inch forcemain from
12 am to 5 am at a rate of 235 gallons per minute. An evaluation of storage and pumping based
on the information provided under this option for a seven-day period is provided in Table 2-1.
Table 2-1: Off Peak Storage and Pumping Analysis
DayVolume Pumped
to Ansonia
(Gallons)
Volume Stored atthe Derby WPCF
(Gallons)
Overflow Volume tobe Treated Onsite
(Gallons)
Derby DailyWastewater
Volume (Gallons)
1 70,500 1,529,500 0 1,600,000
2 70,500 2,000,000 1,059,000 1,600,000
3 70,500 2,000,000 1,529,500 1,600,000
4 70,500 2,000,000 1,529,500 1,600,000
5 70,500 2,000,000 1,529,500 1,600,000
6 70,500 2,000,000 1,529,500 1,600,000
7 70,500 2,000,000 1,529,500 1,600,000
Total 493,500 Note 1 8,706,500 11,200,000
1 – The storage volume of the Derby WPCF is completely utilized within the first two days. Since the storage is never emptied thetanks would remain at 2.0 million gallons until being emptied.
The option presented by the City of Ansonia only accounts for the average daily flow and does
not take into account peak/variable flows. On average, the Derby WPCF currently treats 1.6
MGD which is equivalent to 1,111 gpm. Under this scenario, only 70,500 gallons per day would
be sent to the Ansonia WPCF for treatment. The remaining flow would have to treated at theDerby WPCF, thus the regional concept is not feasible as presented by this alternative, and was
eliminated from further consideration.
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2.4.2 Option 2 – Storage at Derby WPCF and Off-Peak Pumping to Ansonia and Additional
Storage within a 15-inch RCP sewer.
Option #2, which was prepared and proposed by UIC on behalf of the City of Ansonia, is similar
to Option #1 with the exception that the 6” forcemain is replaced with a 15-inch RCP gravity
sewer from the Derby WPCF to the Ansonia WPCF. Under this scenario, a second pumping
station is provided at the Ansonia WPCF to lift the flows into the primary settling tanks. The 15-
inch RCP gravity sewer provides an additional storage volume of approximately 74,000 gallons
after the 2.0 million gallons of storage at the Derby WPCF. Based on the information depicted
on existing plans the Derby WPCF is at a site elevation of approximately 10 feet with an influent
24-inch gravity sewer at an elevation of -4.6 feet. The Ansonia WPCF is at a site elevation of
approximately 23 feet with an influent 27-inch gravity sewer at an elevation of 3.5 feet. The
proposed gravity sewer would have to be installed against grade by a minimum of 13 feet for a
distance of approximately 9,000 feet. Like Option #1, Option #2 is not feasible for the reasons
outlined in Option #1 and was eliminated from consideration.
2.4.3 Option 3 – Storage and Pumping at Derby WPCF with conveyance to the Ansonia
WPCF Influent Pumping Station via a 15-inch RCP interceptor.
Option #3, which was prepared and proposed by UIC on behalf of the City of Ansonia, is similar
to Option #2 with the exception of the following:
• The use of the Derby WPCF for preliminary and primary treatment has been eliminated.
• The Derby WPCF Influent Pumping Station is used for pumping of wastewater to
Ansonia,
• The 15-inch RCP gravity sewer connects to the Ansonia WPCF influent pumping station
wetwell rather than the primary settling tanks,
• Three sewer interceptor layouts were provided. The costs for the interceptor layouts
ranged from $8.9 to $5.7 million.
Since proposed pumping information was not provided, a flow and storage analysis for this
alternative could not completed. It should be noted that the cost estimates for each layout
included two (2) packaged pumping stations, neither of which were noted in the discussion of
each option. The City of Derby has noted on numerous occasions to the City of Ansonia that if
the interconnection were to happen a new pumping station would be provided. Due to
construction staging and redevelopment requirements for the Derby WPCF Site, the City of
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Derby will not re-use the existing influent pumping station under any interconnection. This
alternative does not include the screening and grit removal systems at the Derby site as
previously required by Ansonia. Also, as noted in the analysis of Option #2, the information
depicted on existing plans, the Derby and Ansonia WPCF’s are at elevations that do not support
the installation of a gravity interconnection.
Options #1 and #2, as described above, were discussed at a joint meeting between the City of
Ansonia and City of Derby which was held on March 12, 2012 at the City Hall of Ansonia. At
this meeting, the City of Derby WPCA noted that each of these options was not viable for the
reasons noted above. The City of Derby also requested information including an acceptable
pumping rate, the capital connection fee, and the anticipated user fee structure from the City of
Ansonia. To date, this information has not been provided to the City of Derby WPCA. A copy of
the meeting minutes from this meeting are provided in Appendix F.
Option #3, was presented to the public on September 3, 2013 by Ansonia Mayor James Della
Volpe as part of a press conference during his re-election campaign. Since no pumping/storage
information was provided, an analysis of this alternative could not be completed. Due to the
discrepancies between the write-up of Option #3 and the cost estimates, it appears as through
Option #3 is Option #2 with several different interceptor sewer routes.
None of the alternatives presented by the City of Ansonia appear to be viable. In addition to the
information provided above, each of the options from the City of Ansonia assumes that the City
of Derby will remove unrealistically high quantities of I/I, thus reducing the annual average daily
flow from 1.6 MGD to 1.2 MGD and the peak flow from 10.0 MGD to 3.2 MGD. Each of the
options presented by the City of Ansonia assume that the Derby collection system has a
combined I/I of 1.4 MGD which is cited from a 2007 I/I study, prepared by Milone and
MacBroom. However, that 2007 I/I study was focused on only the Hawthorne Avenue area and
not the entire collection system. The systemwide I/I value based on actual flow metering data
exceeds 10 MGD.
2.5 Partial “Turnaround” Project
Portions of the Derby collection system are located adjacent to the Ansonia collection system,
making it possible to divert flows from these areas to Ansonia’s collection system. As part of the
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future planned upgrades to the collection system, Derby plans to eliminate the inverted siphon
and trunk line that conveys flow from East Derby under the Naugatuck River to the Derby
WPCF. These pipelines present hydraulic restriction points and are maintenance intensive due
to access and flood plain issues. These issues can all be alleviated by installing a new pump
station and force main to eliminate the inverted siphon and trunk line. The new force main route
could be laid out to discharge to Ansonia rather than the Derby WPCF. The peak flow measured
during the flow metering program in East Derby was 4.82 MGD. By installing the force main
from the proposed station to the Ansonia WPCF, a regional solution can be made without
exceeding the peak hydraulic capacities at either WPCF. Approximately 0.22 MGD of peak I/I
would need to be removed from East Derby for this alternative to be effective. The proposed
force main route and pump station location can be seen on Figure 1-3.
In discussions with the City of Derby, the financial impacts to the WPCA associated withmaintaining the system and the WPCF while losing half of the flow would be unsustainable. The
City of Derby WPCA noted that only interconnection options which eliminated the operations of
the WPCF would be considered. As such this alternative was eliminated from consideration.
2.6 Fountain Lake Industrial Park
Over the course of the planning period it is expected that the Fountain Lake Industrial Park will
be expanded from its current location in Ansonia into Derby. Average daily flows of up to
348,500 gpd at maximum build-out have been projected for the industrial park. Over theplanning period it is expected that approximately 25% of the industrial park will be occupied and
contribute an average daily flows of 87,125 gpd. Based on the recommendations in Derby’s
Conservation and Development Plan the flows from the Fountain Lake Industrial Park should be
directed to the Ansonia collection system.
2.7 Alternatives Scoring Matrix for Economic and Non-Economic Factors
A summary of the interconnection alternatives recommendation matrix analysis for
recommendation of a preferred regionalization option is provided in Table 2-2. As noted abovesince the Shelton is not interested in interconnection and the options provided by the City of
Ansonia are not viable they are not been included in the matrix analysis.
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Table 2-2: Matrix Analysis – Interconnection/Regionalization Recommendation Matrix
Criteria Alternative #1 –Pump to Ansonia(Section 8.5.3.1)
Alternative #2 – Pump to Ansonia – 36-inch effluent to Housatonic
River (Section 8.5.3.2)
Fountain Lake(Section 8.5.5)
Flow Feasibility 1 1 5
Concept Feasibility 5 5 5
Ansonia WPCFUpgrades requiredfor 20-year + peakflows
1 1 5
Eliminates Ansonia
EffluentPhosphorousRequirements
1 5 1
Required Army Corp/ Rail PermittingIssues
3 2 5
RequiredConnecticut DOTPermitting Issues
3 2 5
Derby’s Ability toControl Costs
1 1 3
Reduced DerbyStaffing
3 3 1
Ability to ImplementPlanned Growth
1 1 5
Allows for Re-Development of
Derby WPCF Site
2 2 1
Requires less than 1MGD in Storage atDerby PS Site
1 1 5
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Criteria Alternative #1 –Pump to Ansonia(Section 8.5.3.1)
Alternative #2 – Pump to Ansonia – 36-inch effluent to Housatonic
River (Section 8.5.3.2)
Fountain Lake(Section 8.5.5)
Requires more than
1 MGD of I/IRemoval by Derby
1 1 5
Addresses FutureNPDES PermitRequirements
5 5 5
Total 28 30 51
The ranking criteria range from 5 being excellent to 1 being poor. The interconnection with the
City of Ansonia through the Fountain Lake Industrial Park Development alternative has the
highest overall ranking, and is the only alternative that is feasible at this time.
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3. Recommendation
Based on the analysis and discussion above, it is recommended that the City of Derby meet its
wastewater needs by maintaining operations of the Derby WPCF. The Derby WPCF has
capacity to accept additional flow from the Towns of Orange and Seymour. The amount of
additional flow the WPCF can accept will increase after the implementation of an annual I/I
removal program as described earlier in the report. Derby should also pursue regional solutions
with Ansonia as described in the Derby Conservation and Development Plan by directing all
future flows from the Fountain Lake Industrial Park to the Ansonia collection system.
Other options for regionalization with the City of Ansonia do not appear to be an effective
solution at this time due to the limited capacity at the Ansonia WPCF to handle the I/I induced
fluctuation in flows in the Derby collection system or the 20-year planning flows from both
communities. The viability of the interconnection should be assessed again within the next 10
to 15 years, prior to the Phase II upgrades to the Derby WPCF noted herein. Prior to the re-
assessment of the interconnection viability the following actions need to be taken by both
communities:
• The City of Ansonia must assess the upgrades need to the Ansonia WPCF to increase
the permitted capacity to allow for planned growth / economic development within both
the City of Ansonia and the City of Derby.
• The City of Derby must begin a I/I removal program to reduce the peak I/I flow from the
Derby collection system.
The City of Derby met with the Connecticut Department of Energy and Environmental Protection
(CTDEEP), City of Ansonia, UIC, HDR Engineering, Inc., and Weston & Sampson Engineers,
Inc. on October 15, 2012 at the CTDEEP offices to discuss the status of the interconnection
analysis and its feasibility. At the meeting the following was recognized by all parties:
• The interconnection was currently not feasible,
• The interconnection would take a minimum of 15 to 20 years to implement.
•
The City of Derby collection system contains excessive infiltration and inflow volumesand is in the process of conducting an SSES,
• The goal of any I/I project is to remove 50% of the I/I but realistically only 30% of it can
typically be removed,
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City of Derby, Connecticut
Derby-Ansonia Feasibility Study 3-2
April 2014
• Ansonia was not interested in creating a regional WPCA with a WPCA board consisting
of members from both communities, and
• The Derby WPCA would be responsible for maintaining its collection system and would
be a paying customer to the Ansonia WPCA.
At the conclusion of the meeting CTDEEP recommended that the Derby and Ansonia WPCA’s
develop subcommittees to keep open lines of communication regarding the possibility of
regionalizing their wastewater services at some point in the future. CTDEEP also
recommended that the subcommittees meet annually to discuss the status of each system, I/I
removal and to keep lines of communication open regarding the possibility of an
interconnection. A copy of the meeting minutes is provided in Appendix G.
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APPENDIX A
Regionalization Letters
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APPENDIX B
UV System Hydraulic Issues
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APPENDIX C
Storage Analysis Data and Results
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M I L L I O N S O F G A L L O N S S T O R E D
EQUALIZATION STORAGE EVALUATION - 10 MG
3,000 GPM (4.32 MGD)
4,000 GPM (5.76 MGD)
5,000 GPM (7.20 MGD)
6,000 GPM (8.64 MGD)
7,000 GPM (10.08 MGD)
TOTAL DAILY FLOW
PUMPING RATES
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PUMP RATE 3,000 4,000 5,000 6,000 7,000
REQUIRED
STORAGE (GAL) 8,027,500 3,410,000 1,766,667 715,833 0
2011 FLOW DATA
REQUIRED STORAGE (GAL)
DERBY, CT
DERBY WASTEWATER TREATMENT FACILITY
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Quantity Unit Unit Cost Description Cost
9,000 LF $250 Forcemain $2,250,000
2,200 CY $100 Rock Excavation $220,000
2,000 CY $75 Unsutiable Material $150,000
2 EA $500,000 Forcemain Railroad Pipe Jacking $1,000,000
10 EA $15,000 Forcemain Structures $150,000
1 LS $500,000 Ansonia WPCF Primary Clarifier Interconnection Structure $500,000
2,000 LF $10 Cross Country Area Restoration $20,000
7,000 LF $25 Temporary Pavement $175,000
7,000 LF $45 Permanent Pavement $315,000
24,000 SY $20 Milling and Overlay Pavement (1 1/2") $480,000
2,000 HR $65 Traffic Control Allowance $130,000
1 LS $100,000 Concrete Road Base Allowance $100,000
1 LS $250,000 Dewatering $250,000
1 LS $420,000 Contractor Bonds & Insurance (7.5%) $420,000
Forcemain Subtotal $6,160,000
4 EA $60,000 Drypit Wastewater Pumps $240,000
1 LS $200,000 Backup Generator $200,000
1 LS $500,000 Electrical System $500,000
1 LS $350,000 Instrumentation Control System $350,000
1 LS $200,000 Process Piping $200,000
1 EA $350,000 Fine Screen $350,000
1 EA $450,000 Grit Removal System $450,000
1 LS $500,000 Equipment Installation $500,000
2,000 CY $1,000 Cast In place Concrete Drypit/Wetpit (40ft deep) $2,000,000
6,000 SF $250 Pumping Station CMU Operations Building $1,500,000
1,000 SY $45 Paving $45,000
9,000 CY $75 Excavation $675,000
1 LS $500,000 Support of Excavation $500,000
1 LS $250,000 Dewatering $250,000
1 LS $500,000 Site Modifications, Utilities, Piping Modifications $500,000
1 LS $620,000 Contractor Bonds & Insurance (7.5%) $620,000
Pumping Station Subtotal $8,880,000
2 EA $4,000,000 4 MG Prestressed Concrete Tank w/ Mixing/ Odor Control $8,000,000
1 LS $600,000 Contractor Bonds & Insurance (7.5%) $600,000
Wastewater Storage Subtotal $8,600,000
1 LS $3,500,000 Demolition and Removal (existing WPCF) $3,500,000
Derby / Ansonia Regionalization Interconnection
Drypit Wastewater Pumping Station and Forcemain
Engineer's Opinion of Probable Construction Costs
Forcemain
Wastewater Pumping Station
Wastewater Storage
WPCF Demolition
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Quantity Unit Unit Cost Description Cost
9,000 LF $250 Forcemain $2,250,000
2,200 CY $100 Rock Excavation $220,000
2,000 CY $75 Unsutiable Material $150,000
2 EA $500,000 Forcemain Railroad Pipe Jacking $1,000,000
10 EA $15,000 Forcemain Structures $150,000
1 LS $500,000 Ansonia WPCF Primary Clarifier Interconnection Structure $500,000
2,000 LF $10 Cross Country Area Restoration $20,000
7,000 LF $25 Temporary Pavement $175,000
7,000 LF $45 Permanent Pavement $315,000
24,000 SY $20 Milling and Overlay Pavement (1 1/2") $480,000
2,000 HR $65 Traffic Control Allowance $130,000
1 LS $75,000 Concrete Road Base Allowance $75,000
1 LS $200,000 Dewatering $200,000
1 LS $410,000 Contractor Bonds & Insurance (7.5%) $410,000
Forcemain Subtotal $6,075,000
10,000 LF $425 36" PVC $4,250,000
2,200 CY $100 Rock Excavation $220,000
2,000 CY $75 Unsutiable Material $150,000
2 EA $500,000 Railroad Pipe Jacking $1,000,000
1 EA $500,000 Flood Dike Pipe Jacking $500,000
1 LS $300,000 Derby WPCF Effluent Interconnection Structure $300,000
1,000 LF $10 Cross Country Area Restoration $10,000
3,500 LF $25 Temporary Pavement $87,500
3,500 LF $45 Permanent Pavement $157,500
12,000 SY $20 Milling and Overlay Pavement (1 1/2") $240,000
2,000 HR $65 Traffic Control Allowance $130,000
1 LS $75,000 Concrete Road Base Allowance $75,000
1 LS $200,000 Dewatering $200,000
1 LS $540,000 Contractor Bonds & Insurance (7.5%) $540,000
Effluent Modificaitons Subtotal $7,860,000
2 EA $4,000,000 4 MG Prestressed Concrete Tank w/ Mixing/ Odor Control $8,000,000
1 LS $600,000 Contractor Bonds & Insurance (7.5%) $600,000
Wastewater Storage Subtotal $8,600,000
1 LS $3,500,000 Demolition and Removal (existing WPCF) $3,500,000
1 LS $263,000 Contractor Bonds & Insurance (7.5%) $263,000
WPCF Demolition Subtotal $3,763,000
Ansonia WPCF Effluent Modifications
Derby / Ansonia Regionalization Interconnection
Drypit Wastewater Pumping Station, Forcemain and WPCF Effluent Relocation
Engineer's Opinion of Probable Construction Costs
Forcemain
Wastewater Storage
WPCF Demolition
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Quantity Unit Unit Cost Description Cost
Derby / Ansonia Regionalization Interconnection
Drypit Wastewater Pumping Station, Forcemain and WPCF Effluent Relocation
Engineer's Opinion of Probable Construction Costs
4 EA $60,000 Drypit Wastewater Pumps $240,000
1 LS $200,000 Backup Generator $200,000
1 LS $500,000 Electrical System $500,000
1 LS $350,000 Instrumentation Control System $350,000
1 LS $200,000 Process Piping $200,000
1 EA $350,000 Fine Screen $350,000
1 EA $450,000 Grit Removal System $450,000
1 LS $500,000 Equipment Installation $500,000
2,000 CY $1,000 Cast In place Concrete Drypit/Wetpit (40ft deep) $2,000,000
6,000 SF $250 Pumping Station CMU Operations Building $1,500,000
1,000 SY $45 Paving $45,000
9,000 CY $75 Excavation $675,000
1 LS $500,000 Support of Excavation $500,000
1 LS $250,000 Dewatering $250,000
1 LS $500,000 Site Modifications, Utilities, Piping Modifications $500,000
1 LS $620,000 Contractor Bonds & Insurance (7.5%) $620,000
Pumping Station Subtotal $8,880,000
OPC Construction Sub Total $35,180,000
Contingency (20%) $7,036,000
Engineering and Implmentation (20%) $7,036,000
OPC Project Cost $49,252,000
NOTE:1
2
3
This OPC does not include the costs associated with the connection fee to the Ansonia WPCF
This OPC does not include costs for additional upgrades which will be required to the Ansonia WPCF
Wastewater Pumping Station
This OPC does not include mitigation costs for identification and removal Inflow & Infiltration
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Office Account2600-270-0270 Social Security Taxes $56,006200-110-0110 Office Wages $71,666200-110-0112 Employee Secretarial $1,40
6200-110-0110 Part Time Wages $30,006200-150-0150 Office Instruction $946200-150-0152 Accounting $9,50
6200-150-0153 Computer Service $2,506200-160-0161 Town Clerk $2,606200-160-0162 Atty Sheriff Title Search $2,506200-160-0163 Med/Life/Worker Comp Ins $270,006200-270-0270 Insurance $28,206200-270-0271 Postage/Printing $5,506200-270-0272 Birmingham Billing $3,206200-320-0320 Business Forms $2,716200-330-0330 Office Supplies $1,006200-640-0640 Retiree Medical $6,58
Office Accounts Total $494,31
Plant Accounts6200-110-0111 Superintendent $88,29
Mechanic $64,18 Grade 2 $60,38 Grade 2 $60,38 Grade 2 $60,38
6200-120-0120 Overtime Wages $60,006200-150-0151 Operator Instruction $3,006200-160-0164 Vehicle Maintenance $10,006200-220-0220 Electric $70,00
6200-230-0230 Gas Heat $14,006200-230-0232 Water $1,20
6200-400-0430 Special Clothing $3,006200-400-0432 Pest Control $556200-400-0434 Collection System Maintenance $275,006200-400-0435 Collection System Rehabilitation $200,006200-440-0440 Pump Station Maintenance $165,006200-460-0461 BFI Rags Grit Grease $4,506200-480-0484 General Engineer Costs $60,006200-490-0498 Working Balance $85,006200-480-0495 Vehicle Replacement $75,00
Operations Accounts Total $1,359,88
Grand Total $1,854,20
Office Accounts
System Operations Accounts
City of Derby Water Pollution Control Authority
Estimated System Maintenance Budget - Ansonia Interconnection
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APPENDIX E
Ansonia Interconnection Alternatives – UIC Reports
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APPENDIX E
UIC – City of Ansonia Interconnection Report
Interconnection Option #1 through #3
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ANALYSIS REPORT
DERBY WPCF, DERBY, CT
The City of Derby, CT has expressed a need to adequately treat the sanitary flows generated
within the sewer system limits without expending a large amount of funds on upgrading the
existing Water Pollution Control Facility (WPCF). In doing so, the City must look at several
options for handling not only the existing sanitary flows, but flows that are projected to increase
over the next twenty years. For the purposes of this report, the option of transferring the City’s
wastewater flows to the Ansonia WPCF will be analyzed.
The primary concern will be the capacity of the Ansonia WPCF to handle the increased flows
from Derby. The Ansonia facility is permitted to handle and treat a design flow of 3.5 million
gallons per day (MGD), with a peak capacity of 7.0 MGD. The Derby WPCF has a design
capacity of 3.5 MGD with a peak flow capacity of 9.1 MGD. Both facilities’ daily flow records
over a three-year period were analyzed to determine an average daily flow and a maximum
daily flow. This information is presented in Table 1.
Table 1. Daily Flows from Plant Data
Derby WPCF – design flow capacity 3.5 MGD, peak flow capacity 9.1 MGD*
Year Average Daily Flow (MGD) Maximum Daily Flow (MGD)
2009 2.21 6.41
2010 3.01 8.08
2011 2.91 5.30*Data taken from Facilities Planning Study, 1997.
Ansonia WPCF – design flow capacity 3.5 MGD, peak flow capacity 7.0 MGD
Year Average Daily Flow (MGD) Maximum Daily Flow (MGD)
2009 1.72 5.08
2010 2.25 5.73
2011 1.80 3.50
As can be seen, the maximum daily flows from Derby WPCF, in addition to the Ansonia flows,
will exceed the Ansonia WPCF peak flow capacity. Therefore, the flows from Derby must be
restricted in some manner so as not to exceed the capacity of the Ansonia facility. This can be
accomplished by releasing the flows from Derby at a controlled rate which will not adversely
affect the treatment capacity at Ansonia. There are several options to consider:
Option #1: Store the Derby sanitary flows at the Derby WPCF and pump them through a
force main to Ansonia at a controlled rate. The existing treatment structures would be usedas storage/equalization basins. Storing the sanitary sewage at Derby would entail removing
the treatment equipment from the existing Primary Settling tanks, Aeration Basins, and
Clarifiers and using these structures strictly for storage/equalization. Two (2) Primary
Settling Tanks have a combined volume of 215,424 gallons, 3 Aeration Basins have a
combined volume of 1.34 million gallons (MG), and 2 Clarifiers have a combined volume
of 423,000 gallons. The total volume of daily sewage that can be stored is nearly 2 million
gallons. Attachment 1 presents an overhead image of the existing WPCF showing the
locations of these structures. Some form of primary treatment, such as bar screens or
comminutors, would be required to prevent the entry of larger solids through the
equalization facilities. This treatment is capable of removing approximately 60% of the
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solids in the influent stream. The sewage could then be pumped via force main at a
controlled rate to the Ansonia facility. The length of the force main, approximately 8,000
linear feet between the facilities, would require sewage lift stations along the route to
maintain system pressure. A 6-inch, poly-vinyl chloride force main could pump the sewage
to Ansonia and release the flows at approximately 235 gallons per minute. The pumping
from Derby could be timed such that during low treatment flow periods, 12AM to 5AM for
example, the Ansonia WPCF would not be overburdened by the additional sewage flows in
terms of capacities and biological loadings.
Option #2: Install a sewer connector between the Derby and Ansonia WPCFs. A 15-inch
or larger reinforced concrete sewer interconnect of approximately 8,000 linear feet could
serve as a storage facility, storing at least 74,000 gallons of sewage until it can be released
into the Ansonia facility. The flow would be a controlled release to minimize the influent
affect on the Ansonia facility. This option could reduce the need to store as much flow in
the Derby facility and allow some form of primary treatment, such as settling, to occur
before the flows are pumped to Ansonia. The Primary Settling Tanks can remove as much
as 65% of suspended solids in the influent. In doing so, the treatment load at Ansonia could
be reduced. The interconnect system may require a pumping station at the Derby WPCF to
pump the sewage through the interconnect, with lift stations to maintain the flow within the
pipe. An alternative would be to install a pump station to pump the sewage from the Derby
facility, install the interconnect with sufficient slope to maintain flow, and construct a liftstation just prior to the Ansonia facility to pump flows into that WPCF.
Each of the previous options is based on the assumption that infiltration and inflow into the
Derby sewer system contributes to the maximum daily flow rate. Infiltration into a sanitary
sewer system occurs when rainfall events introduce storm water into the system through
deficiencies in piping, structures, and connections. Inflow into a sanitary system is due to
improper connections of roof drains, yard drains, etc., that are connected to the sanitary
system. Inflow connections introduce storm water into the sanitary system that should
otherwise be directed through the storm sewer systems. In many municipalities across the
country, these connections are illegal. An infiltration/inflow (I/I) analysis is discussed later
in this report. Option #3 addresses the actions necessary to reduce I/I in the Derby system.
Option #3: To reduce I/I in the Derby sanitary system and thus reduce the maximum flows
that occur during wet weather events, the entire sanitary sewer system should be replaced or
lined with cured-in-place (CIP) pipe linings. The areas of the sanitary system that have not
been studied should be included in a broad program using closed-circuit televising (CCTV),
smoke testing, and dye testing to identify sources of inflow and infiltration. CCTV will
identify those segments of sewer pipe and structures (e.g. manholes) that must be replaced
due to condition, and those segments that are candidates for CIP lining. Both methods will
significantly reduce infiltration into the system. Smoke and dye testing will identify
sources of inflow that should be removed from the sanitary system. A comprehensive
program to eliminate I/I sources would reduce the maximum flows in the system by at least
60%. Once the flows have been significantly reduced, then an analysis of the total flows
required to be treated by the WCPF will be significantly low.
Implementing a comprehensive I/I reduction program, removing inflow sources and
replacing and/or rehabilitating the system piping, will reduce the capacity required for
storage/equalization and reduce the sanitary flows to Ansonia WPCF. Other advantages
include reduced capacity loads on Ansonia WPCF with reduced operating, maintenance,
and replacement costs at both WPCFs.
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development/redevelopment occur as planned, will be 2.38 MGD. Any improvements or
modifications required to direct sanitary flows to the Ansonia WPCF must include the
projected sanitary flows in the design to provide sufficient capacity for growth.
Conclusions/Recommendations
The flow data from the two WPCFs indicates that, if the flow from Derby is taken to
Ansonia without a controlled equalization process and flow rate, the combined flow for 180
consecutive days will exceed 90% of the present average design flow rate of Ansonia
WPCF. This will trigger a requirement for the Ansonia WPCF as stated below:
Section 4(L) of Ansonia WPCF’s NPDES Permit issued on June 27, 2001states:
When the arithmetic mean of the average daily flow from the POTW for the previous 180
days exceeds 90% of the design flow rate, the permittee shall develop and submit for the
review of the Commissioner within one year, a plan to accommodate future increases in
flow to the plant. This plan shall include a schedule for completing any recommended
improvements and a plan for financing the improvements.
Additionally, the treatment processes at the Ansonia facility may not be able to support
untreated sanitary flows from Derby. Therefore, a process step of equalization, along with
primary treatment, must be instituted to allow the processes at Ansonia to effectively treatthe increased sanitary flow. Using the existing treatment structures as storage/equalization
basins, while removing all treatment equipment from these structures, will allow the City of
Derby to appreciably reduce operating costs for this facility. Although minimum operations
would still be required at Derby WPCF, for example, monitoring of pumping and screening
operations, the City of Derby can budget for lower operating costs and lower maintenance
costs for this plant.
An active program to reduce the I/I contributing to the Derby sanitary sewer system should
be implemented throughout the entire system. This program could reduce the I/I
contributions by at least 60%, thereby significantly reducing the flows from the City of
Derby to the Ansonia WPCF.
Feasibility Study
If the project as described is approved, the City of Derby should initiate and complete a
comprehensive feasibility study, or a preliminary engineering report, to analyze each option
as presented for practicality, cost/benefit, constructability, and socio-economic impact. The
purpose of such a study is to analyze all options to determine the best in terms of how much
will it cost to construct, what will be the long term benefits, how will the option affect
future growth, and which will provide the best results. In order to accomplish such a study,
the data collection effort should include the following:
1.
Site investigation. Site investigations will include a site visit by the design team,
interviews with personnel familiar with the project, and an understanding by the designteam of the client’s requirements. The site visit will provide the design team with an
assessment of the existing conditions for each option, the limitations and constraints of
each option, valuable information from the owners/operators of each WPCF, and
background information to provide an overall scope of the project design. Site
investigation will also include:
geotechnical investigations to determine the composition and stability of the
existing soils,
topographic surveys to provide a visual picture of the land surface, existing utilities,
structures, appurtenances, and other possible impediments to each option,
right-of-way and utility easement surveys,
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obtaining and reviewing existing utility plans,
closed-circuit televising of existing sewer segments,
manhole and structure investigations,
smoke and dye testing.
2.
Environmental investigation. The environmental phase of the feasibility study will
address cultural, historic, and environmental factors in the design process. Following
the guidelines as set forth in the Connecticut Environmental Policy Act (CEPA), each
option will be assessed as to its impact on local and state environmental, archeological,
cultural, and historical assets for both the City of Derby and City of Ansonia. CEPA
provides for specific guidance on for conducting Environmental Impact Evaluations
(EIE), which are investigative documents that look at how the project will affect the
local and state environmental resources, air and water quality, noise, socio-economic
assets, historical/archeological and national landmarks, and cultural impacts. The EIE
process also provides the public with a vehicle for commenting on the project and
having their concerns taken in account prior to construction. The Consultant should
research all available federal, state, and local regulatory data concerning both WPCFs’
operations, permitting, violations, and corrective actions, if taken.
3. Concept design investigation. The concept design investigation phase begins with a
detailed analysis of all available historical documentation, plant flow data, treatmentand laboratory data, as-built drawings, previous studies, and engineering reports
concerning the existing facilities. At this stage of the feasibility study each option is
thoroughly examined in regards to size, equipment, location, materials, constructability,
and probable cost estimates.
4. Report phase, conclusions/recommendations. Once the design investigation is complete,
all the data collected will be compiled and designed into a feasibility report for
presentation to the client. The report will detail all actions taken from each
investigation phase and present findings and conclusions, and a preferred option, giving
the relevant justification for and against each option. The preferred option will be
recommended based on costs, benefits, ease of construction, limited impact on the
community and environmental resources, and value.
Att (3): 1. Figure 1. Aerial View of Derby WPCF
2. TECHNICAL MEMORANDUM, Wastewater Facilities Plan, Weston &
Sampson Engineers, Inc., September, 2011.
3. Data Correlation Table for Rainfall and I/I, Derby WPCF
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List of References
1. Technical Memorandum to the City of Derby Water Pollution Control Authority,Weston & Sampson Engineers, Inc., Sept. 2011.
2. Influent and Effluent Qualitative Data Sheets, January 2009 through February 2011,
Derby WPCF, City of Derby, Conn.
3. Sanitary Sewer System Infiltration/Inflow Analysis, Hawthorne Avenue Watershed.
Milone & MacBroom, Inc., MMI #2165-01-12, July 2007.
4. Facilities Plan, Wastewater Treatment Plant and Sanitary Sewerage System. City of
Derby, Connecticut Water Pollution Control Authority, Semi-Final Draft. Cascio
Bechir Engineers. July 1997.
5. Construction Plans. City of Derby, Alterations and Additions to the Water Pollution
Control Plant Pump Stations and Sanitary Sewerage System. Cascio Bechir Engineers.
August, 1998.
6.
Influent and Effluent Qualitative Data Sheets, January 2009 through April 2011,Ansonia WPCF, City of Ansonia, Conn.
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Attachment 1
Figure 1. Aerial View of Derby WPCF
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AERATION BASINS
CLARIFIERS
PRIMARY
SETTLING
TANKS
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Attachment 2
TECHNICAL MEMORANDUM, Wastewater Facilities Plan, Weston & Sampson Engineers, Inc.,
September, 2011.
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Derby
WPCF
Flow
and
Rainfall
Data
Rainfall
Mon/Yr Max Min Avg inches*
for Stevensen Dam rain gage 5.5 mi. WNW o
Jan
09 4.10 0.80 1.72 1.74
Feb
09 3.60 0.70 1.77 1.05
Mar
09 3.40 0.80 2.40 1.41
Apr
09 6.40 0.80 2.10 2.79
May
09 7.50 0.60 1.98 3.95Jun
09 8.90 0.70 3.09 6.57
Jul
09 9.80 0.70 2.57 6.22
Aug
09 7.00 0.60 2.25 4.17
Sep
09 3.40 0.40 1.47 2.07
Oct
09 8.10 0.50 2.31 6.65 Exceeds Derby WPCF design f
Nov
09 7.30 0.80 1.92 2.22 Exceeds Derby WPCF peak flo
Dec
09 7.40 0.90 2.93 5.37
Yr
Avg 6.41 0.69 2.21
Jan
10 6.40 0.80 2.44 2.75
Feb
10 10.00 0.80 4.69 3.24
Mar
10 10.00 1.30 8.10 8.39
Apr
10 10.00 0.70 6.10 1.16
May
10 7.10 0.50 1.54 2.69
Jun
10 5.70 0.30 1.28 3.46
Jul
10 7.80 0.10 1.35 4.82
Aug
10 7.50 0.20 1.41 4.1
Sep
10 8.10 0.30 1.88 2.5
Oct
10 9.30 0.70 2.42 5.87
Nov
10 7.30 0.70 2.38 3.29
Dec
10 7.70 1.00 2.54 4.94Yr
Avg 8.08 0.62 3.01
Jan
11 3.10 0.90 2.04 3.3**
Feb
11 7.50 0.80 3.78 3.67**
Yr
Avg 5.30 0.85 2.91
Design 6.59 0.72 2.71
Avg
Flow
(MGD)
*taken from NCDC rainfall data
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Rainfall
Monthly
Totals
Mon/Yr inches*
Jan
09 1.74
Feb
09 1.05
Mar
09 1.41Apr
09 2.79
May
09 3.95
Jun
09 6.57
Jul
09 6.22
Aug
09 4.17
Sep
09 2.07
Oct
09 6.65
Nov
09 2.22
Dec
09 5.37 Exceeds
Derby
WPCF
design
flow
capacity
of
3.5
MGD
Exceeds
Derby
WPCF
peak
flow
capacity
of
9.1
MGD
See
Table
1.
Derby
WPCF
Flow
Data
Table
Jan
10 2.75
Feb
10 3.24
Mar
10 8.39
Apr
10 1.16
May
10 2.69
Jun
10 3.46
Jul
10 4.82
Aug
10 4.1
Sep
10 2.5
Oct
10 5.87Nov
10 3.29
Dec
10 4.94
Jan
11 3.3**
Feb
11 3.67** **Regional
Climate
Center
state
totals
*taken
from
NCDC
rainfall
data
for
Stevensen
Dam
rain
gage
5.5
mi.
WNW
of
Derby/Ansonia
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APPENDIX E
UIC – City of Ansonia Interconnection Press Release
Interconnection Option #4
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STATEMENT OF MAYOR DELLA VOLPE - SEPTEMBER 5, 2013
I am announcing today my plan to call upon the State of Connecticut and the City of Derby to
work with Ansonia in creating a regional wastewater treatment system that will protect our
environment and save millions of dollars for our ratepayers in both communities.
Within the last few years, Ansonia successfully completed a $50 million upgrade to its water
treatment facility that eliminated excessive pollutant emissions into the Naugatuck River. These
emissions eventually made their way into the Naugatuck river then to the Housatonic and finally
to Long Island Sound. Along the way, they caused harm to fish and wildlife and reduced the
quality of our environment. The Ansonia plant had long exceeded its expected life span and we
were under an order from the state to compete the expensive upgrade which we did. Each
household unit is paying $270 annually to pay down the bonds needed to repay the State of
Connecticut over a 20 year period. Businesses are paying a greater cost for their share of the
bonds.
It is very likely that Derby may be required to undergo a similar challenge in the coming years at
a great cost to the hard working people in that community. I have asked our engineers to examine
the possibility of using the Ansonia treatment facility for the wastewater flows in both
communities.
Their preliminary analysis indicates that this could be accomplished with certain flow mitigation
procedures for infiltration and inflow I/I in derby and the construction of a pumping station and
8000 linear foot pipe carrying the flow from Derby to Ansonia.
The Ansonia wastewater treatment facility has a design flow of 3.5 million gallons per day with
a peak capacity of 7.0 million gallons per day (MGD).
During the 3 years from 2009 through 2011 Ansonia’s average daily flow (ADF) ranged from
1.72 MGD to 2.25 MGD while Derby’s ranged from 2.21 MGD to 3.01 MGD. The maximum
flows were 8.08 in Derby and 5.73 in Ansonia which would overburden the Ansonia plant on
maximum flow days.
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However, a good portion of the Derby maximum flow is due to particular challenges with
infiltration and inflow I/I which could be mitigated by at least 60% with a successful remediation
program.
Upon completion of such a program, the State of Connecticut could create financial incentives
for the two towns to “hook up” their systems so that the necessity of eventually rebuilding or building a brand new plant in Derby could be avoided. Instead, by using a combination of I/I
mitigation in Derby, storage of flow at the Derby plant and controlled flow timing during the late
evening or early morning hours, the flow from that city could be treated n Ansonia.
This could create enormous benefits for the residential and business ratepayers in both
communities:
• The staffs and workers of both WPCAs could be protected with job security and through
the use of eventual retirement attrition savings could be realized over the long term
•
Each community would retain its separate functions of rate setting and collections andDerby could make semiannual payments to the Ansonia WPCA for use of its treatment
facility
• The people of Derby would avoid the long term cost of building a new plant and the
people of Ansonia could see their $270 annual capital fee reduced by as much as 50%
• Our environment and rivers would be protected for generations by the elimination of
harmful water pollution
• The approach could serve as the model for future collaboration in two small neighboring
communities that are attempting to reinvent their local economies for a brighter future
• The State of Connecticut could use this approach in smart regionalism to save millions of
dollars in bonding costs for our two communities while using it as a model for similarapproaches elsewhere in the future.
I call upon the Department of Energy and Environmental Protection (DEEP), with the
encouragement of our two legislators, Senator Crisco and Representative Gentile, to immediately
begin a comprehensive feasibility study to carefully examine this proposal with an eye to the
economic and environmental benefits to our region and state.
The feasibility study would consider both economic and non-economic factors in arriving at the
most desirable alternative for implementation. A present worth economic analysis would be
performed as part of the evaluation. The economic analysis would incorporate capital, operationand maintenance cost estimates developed for each alternative.
By working together as neighboring communities with a long history of cooperation and with the
state, we could use smart regionalism to protect our future and reduce the cost of living and
doing business in each of our communities.
Thank you very much.
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ANSONIA-DERBY
INTERCONNECTOR
Preliminary
Analysis
A. Ansonia-Derby Interconnector
As shown
on
the attached map, the
following three
alternative routes were analyzed
for
routing the
interconnector. Each route connects the ef{luent from the Influent
Pump
Station of the Derby
V/ater Pollution Control Facility
(V/PCF)
to the
wet
well of the
Influent Pump
Station
at the Ansonia
\I"PCF.
'Ihe
proposed
routes
of
the
server
interconnector
are
presented
as follows:
Option #l:
The
route
for Option
#1
proceeds
&orn the Derby W?CF Influent Punp
northo
crossing
unclemeaih the existing
railroad
immediately
north of
the
WPCF,
continuing north
along the
east
side of Caroline St., crossing
under
Main St., then
continuing norlh
along
Caroline
St.
until
turning
northeast at
Cottage
St.
From this
point,
the
route
continues
through a
vegetated
area untii
reaching
Route B,
rvhere
it
will
cross
under
this
road, then continue norlheast along the west side of
Pershing
Dr. until
r'eaehing
the Ansonia
llv?CF, r,''here
it
will
turn east,
crossing under
Pershing
Dr.
and then under another
railroad,
and
conlinuing to the
ilfluent
*'et
well for Aasonia WWTP. The route
will
take
the sewer
through
several
commercial/industrial
areas
with
paved
parking
areas. The
sewer
is
to be iS-inch
reinforced
concrete
pipe (RCP)
with an
approximate length of
8,000 linear
feet
(LF).
Option
#2:
The rsute
for
Opticn
#2 proeeeds
from
the
Derby
WPCF
Influent
Pump
east,
crossing under
Route 8,
then continuing
east uritil turning north
approximately
550 feet
east of
the
WPCF.
The
route
crosses
under an
existing railroad, contiluing
ncrth
through a vegetated area,
crossing under
Main St. east of the
intersection
with
Route 8, then
conlinues north,
following an
existing
railroad,
crossing
underneath
Division
St., continuing to
the
Ansonia W"CF,
This
se:*er
route
will
pass
through
several commereiallindustrial areas
with
par,ed
parking
lots, and may require right-
of-way
acaess
ficm
fhe
or*'ner
of
the existing railroad. The se*'er
is to be i5-ineh
RCP with
an
approxirxate
length of 8,000 LF.
Option
#3:
The route for Option
#3
proceeds
east from the
Derby WPCF
Influent
Pump,
crossing
under Route 8, continuing
east
approximateiy 800 feet until turning
north. The route crosses under
an existing
milroad,
proceeds
north crossing under
Main St. west
of the
intersection
with
Derby Ave.,
then
continues nonh follorving
the Derby
Greenway to Division
St.. crosses under
Division St." then
proeeeds
along N. Division
St.
until turning west
into
Ansonia
WPCF.
This route
takes the
sewer through
predominately
vegetated area until
reaching
the
Divisicn
St.
crossing, then
the route
encounters an
industrial
area west of N. Division St" The
sewer
is
to
be
1
5-inch
RCP installed
at an
approximate length of 8,500 LF.
Parametric Constructicn
Cosf Estirnates
Option #l: The
preliminary
cost estimate for Option #1. including
materials,
labor,
and contingencies
is
$8,900,000.
Option
#2:
The
prelimilary
cost
estimate
for Option
#2,
including
materials,
labor,
and contingencies
is
$7.300,000.
Option
#3:
The
preliminary
cost estimale
for Option #3, including
materials, labor,
and
contingencies
is
$5,700,000-
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B.
Water
Pollution Control
Facilify
(WPCF)
Flow Data Analysis
The
influent flor,r.s
to
l)erby
and
Ansonia
WPCFs
rvere
provided
for
the time
period
January ?009 to February
201
1.
The
monthly
average
flows
from the
limited data
were
analyzed and
are
presented
as
fsllows:
Derby
WPCF
-
design
flow capacity
3.5
MGD,
peak
flow
capacify 9.1
MGD*
Year
2009
2010
201 I
Year
2009
20
l0
201
l
2.21
3.01
2.91
6.4i
8.08
5.30
Average
Daily
Flow'
(MGD)
Maxirnum
Daily
Fiow
{MGD)
*Data
taken from Faoilities
Pianning
Study,
1997.
ln the analysis
period,
the
1VPCF
exceeded its
peak
flow
capacity 5 times,
July
?009,
February
2010,
March
20i0, April
2010" and October
?010.
reaching
a
high
peak
flou'
of
10
MGD
for
the
three months
February to April 2010. The
plant
exceeded its
design
florr
capacity 4 times. Februarv ?010,
March
2010,
April
2010, and F'ebruary
201
1.
Ansonia WPCF
-
design flow
capacity
3.5 MGD,
peak
flow
capacit-v
7.0
MGD
Average
Daily Fiow
(MCD)
Maximum Daily Flow
(MGD)
5.08
5.73
3.50
1.72
2.25
1.80
In
the
analysis
period,
the WPCF exceeded
its
peak
flow
capacity
4
times,
June
2009,
July
2009,
]v{arch
?010, and April
2010.
The plant
exceeded
its design
{low
capacity
in
March
2010.
C. lnfilfratian/Inflow
(I/I)
A comparison was made belween
the
peak
flows to Derby WPCF and
historical rainfall
data
for the
same
period
to
see if
a correlation
could be
established
between
high
peak
flows and above normal rainfal]
eyents.
This
correlation rvould be useful in
determining
if infiltrationjinflow
into Dertry's
u'aste*,ater
sewers
is eontributing
to high
peak
flows to the
plant. For lhe months
analyzed
where
the
plant's
peak florv capacities
r.vere
exceeded, rainfall records
shorv that for June and July 2009, aad March
2010, the
rainfail totals
exceeded
the arca
averages
by over
509/o. The
high minfull
amounts
might indicate that high
I/I
rates were
a contribuling
factor
in
the
plant's
peak
capacify
being
overtaxed. Table
1
provides
the average
WPCF
plant
inflow
data and rainfall
amounts for Derby.
An
Ir'I sfudy produced
for
&e
City
of
Derby
inZAAT shorred that
I/I
volumes
into
the
sanitary sewer system
can be as
high as
1.4
MGD. Reducing
60%
of the I/l
into
the
system
s'ould
resu
b
average
daily
flows approaching
1.2
MGD
and
peak flows
nearing
3.2
MGD. lt
is
our
understandilg
that the City of Derby
is currently
conducting
an
I/I
study of
the
sanitary
sewer systern. Once
the
results of
that study
are
published,
the
correlations
between
sanitary florvs and rainfall
events can
then
be
reevaluated
and
more accurats
measurements of average
and
peak
flows
can
be
obtained.
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E. List
of References
l.
Influent and Effluent
Qualitative
Data Sheets, January 20S9 through February 2011,
Derby WPCF,
City
of
Derby, Conn.
2. Sanitary Sewer
System
Infilrratian/Inflow
Analysis,
Haytthorne Avenue
Watershed.
Milone
&
MacBroom.
Lnc.,
MMI
+t2165-01-12,
July
2007.
3. Facilities Plan,
Wastew*ter
Tr€atffient
Plsnt
and. Sanitary
Eewerage
S1xtern. Cig
of
Derby, Connecticut Water
Pollution Confrol
Authoriry*, Semi-Final
Drafi.
Cascio
Bechir Engineers. July' i997.
4-
Construction
Plans.
Ci*,
af
Derby, AJterqtions and Additians
to
th,e Wafer
Pallution
Control
P[ant
Pump Statians
and Sanitary
Sewerage System. Cascio
Bechir
Engireers.
August,
1998.
5.
Influent
and
Effluent
Qualitative
Data
Sheets,
January 2009
through April
2011,
Ansonia WPCF,
City of
Ansonia,
Conn.
6.
I;acilities
Planning Study, Cily
of Ansonia, Connecticut Water Pollution
Control
Authority.
United International Corporation.
Jul;r
20S4"
7.
Seuter
System Evslusti{}n Sarve , Pkase
I
stzd Ph#se
-II
City of Ansonia,
Connecticut
Water
Pollution Control Authoritl.
United Intemational Corporation.
June
2000.
8. Infiltration/Infiov, Study. Cif of
Ansonia, Connecticut Water
Follution
Control
Authority.
United Intemational Corporation.
September 1 996.
9.
Consfruction
Plans. C/ry of Ansania, Connecticut,
Water
Pollutian Control
Facility
Upgrode. Camp,
Drssser
&McKee,
Inc.
November 7A07.
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