Fishers Ridge
FEIS
Appendix N
LaBella Memorandum Regarding Acceptance of Phase I Flows – 10/11/2016
MEMORANDUM
TO:
Katie Evans, Director of Development
Town of Victor
FROM:
Mike Schaffron, P.E.
Sam Forster
DATE:
October 11, 2016
RE:
Evaluation of Conveyance of Sanitary Flows from Anticipated Development Projects
Tributary to PS – 28 Wendy’s
LaBella Project No 209214.461
A number of large developments have been proposed in the northwest quadrant of the Town’s sanitary
sewer district that will add considerable sanitary flow to the conveyance system. There is currently
concern over conveyance capacity in this area.
Based on recently completed studies, we have initiated the design of sanitary improvements that will
address concerns and provide adequate capacity for many years. These improvements are projected to
be operational in the spring of 2018. Proposed developments also anticipate being operational before
or by this time. Since some or all of the proposed developments could be operational prior to the
Town’s improvements, we evaluated the existing system’s ability to convey the additional flows during
the interim period.
Proposed Development
Proposed developments in the northwest quadrant include:
•
Willis Hill Subdivision: This 34-lot residential subdivision is proposed south of Victor-Mendon
Road, between Willis Hill and Strong Roads. Flows from the development will be conveyed to
PS-24 Route 251 at Wangum and then to down gradient pump stations PS-25 Route 251 at
Phillips Road, PS-27 Phillips Road, and PS-28 Wendy’s. From PS-28 flows will be conveyed to
downstream to PS-32 Willowbrook and to five other pump stations before entering the
wastewater treatment plant on McMahon Road.
•
ConServe: This office/call center with 600 employees through 2017 will be located in the
northwest quadrant of the intersection of Main Street Fishers and Phillips Road. The center will
be in service in the spring of 2017. The ultimate usage of the building could include up to 1,000
employees by 2022. Under the existing sanitary system layout, flows from the development will
be conveyed to PS-28 and then follow the above conveyance to the six other pump stations
before entering the wastewater treatment plant on McMahon Road.
•
Fishers Ridge – Phase 1: A multi-use development including a bowling alley, restaurant and
sporting goods store to be located north of Pittsford-Victor Road (NYS Route 96) between Lane
and Rowley Roads. This phase of the development will be operational in the spring 2018. Under
the existing sanitary system layout, flows from this development will be conveyed to PS-29, the
down grading PS-28 and then follow the above conveyance to six other pump stations before
entering the wastewater treatment plant on McMahon Road.
The developments and anticipated flows are summarized below.
Name
Willis Hill
Subdivision
ConServe –
Ultimate Bldg.
Occupancy
Fishers Ridge –
Phase 1
Development
34 Residential
homes
1,000 person call
center operating on
3 shift
Bowling alley,
restaurant, sporting
goods store
Tributary
Pump Station
Average Daily
Flow, gallons
Peak Hourly
Flow Rate, gpm
PS-24,
11,220
30
PS-28
7,500
55
PS-29
25,325
70
Proposed Improvements
Under existing conditions, sanitary flows are conveyed along a successive chain of pump stations to the
Farmington Wastewater Treatment Plant. Proposed improvements will direct flows originating south of
the Thruway and west of Route 96 around the south side of the Village to McMahon Road and the
wastewater treatment plant. Flow from PS-27 Phillips Road, PS-28 Wendy’s and PS-29 Hadley Circle will
all be directed to a new PS-30 Lehigh Crossing pump station constructed on NYS Route 251 between
Route 96 and Cork Road.
Analysis
Flow in this conveyance system is very dynamic. The Town has no control over the magnitude and
patterns of its usage. In addition, in operating the system, it is difficult to become aware of a potential
issue before an alarm signal is activated at a pump station or a more significant problem, such as a main
break, occurs.
Under the current system configuration, all flow in the District, south of the Thruway and west of Route
96, is conveyed to PS-28. The Town of Farmington, which operates the conveyance system, reports that
since replacing the pumps at PS-28 no high-water alarm conditions have occurred. High-water alarms
could indicate there is not adequate capacity under current conditions or the pumps are not performing
at their rated capacity for various reasons (e.g. excessive wear, debris on the impeller, etc).
Considering the proposed developments will proceed prior to the new PS-30 becoming operational, we
evaluated the performance of PS-28 and PS-29 during the peak hourly and max day conditions. Existing
conditions were determined based on pump station performance during the preceding 12-month
period. We considered the Town of Farmington will have replaced the pumps at PS-29 Hadley Circle
prior to additional development being connected to the system. (Pump purchase was authorized in
September). This is important because recent observation indicated the pumps at PS-29 are severely
underperforming. We did not consider any use of the lag pump. Under the Ten States Standard, the
capacity of the station should be determined considering the largest pump is out of service. Pump
station storage did not consider any storage other than the wet well.
Our analysis indicated:
•
The PS-28 wet well would pump down (to the “All Pumps Off” level) during the peak hour with
the addition of flows from the Willis Hill subdivision and the ConServe development. This would
be an acceptable level of service.
•
The PS-28 wet well would pump down (to the “All Pumps Off” level) during the peak hour with
the addition of flows from the Willis Hill subdivision and Phase-1 of the Fishers Ridge
development. This would be an acceptable level of service.
•
The PS-28 will not pump down (to the “All Pumps Off” level) during the peak hour with the
addition of flows from the ConServe and Phase 1 of the Fishers Ridge development. During the
peak hour, wet well levels will exceed the current high water alarm for periods in excess of 60
minutes. Wet well levels could be nearly 3 feet over the alarm level. This would be an
unacceptable operational condition.
Pump run times will increase in response to the proposed developments. The longest pump run time
recorded at PS-28 in the past 12-months that could be justifiable is 13.2 hours. (Note: There were
longer run times recorded which we considered were indicative of a pump(s) temporarily
underperforming. Substantially longer run times without significant precipitation and without significant
increase in down-gradient pump run times were omitted from consideration.)
ConServe , Fishers Ridge Phase 1 and Willis Hill Subdivision will add 0.4, 1.4 and 0.6 hours, respectively.
The cumulative impact would be an increase of 2.4 hours to PS-28.
PS-29 has a recorded max day pump run time of 14.8 hours. We do not believe the recorded pump run
times at PS-29 are representative of potential future conditions. Recent observations indicate the
station’s pumps are operating around 65 gpm where the rated capacity is 205 gpm. The underperforming pumps would be expected to have significantly longer run times. The Fisher’s Ridge Phase 1
development will add 2.1 hours of pump run time to this station with its new pumps.
We reviewed pump station capacity down gradient of PS-28 Wendy’s. While PS-28 Wendy’s will
experience longer pump cycles, its discharge rate will continue to be 300 gpm. Down-gradient PS-32
Willowbrook and PS-17 Brunswick are rated at 350 and 400 gpm, respectively. We feel these stations
will be able to convey the additional flow from the near-term development during the interim period.
We also evaluated changing the speed, and therefore, the capacity of PS-28. The speed of the pumps
could be increased to approximately 1,800 rpm. This would increase the capacity of PS-28 from 300 to
350 gpm, matching the capacity of the down gradient PS-32 Willowbrook. Under the increased capacity
of PS-28 with all three projects constructed and occupied, the PS-28 wet well would pump down (to the
“All Pumps Off” level) during the peak hour. Existing max day pump run hours would be reduced by
about 2 hours due to the higher pumping rate. With all three developments fully occupied, the higher
pumping rate would result in only a minor net increase of 0.2 hours to the max day pump run hours.
Conclusions
Based on our analysis, it is our opinion that the Town can allow:
•
•
The Willis Hill and either Fishers Ridge Phase 1 or ConSeve to proceed without modification to
PS-28.
The ConServ and Fishers Ridge Phase 1 with or without Willis Hill, to proceed provided the belts
and sheaves for all four pumps at PS-28 be changed resulting in a pump speed of approximately
1,800 rpm and capacity of 350 gpm.
Our opinion considers:
• On-going maintenance will provide for the components to operate at their design capacities
• Efforts to minimize infiltration and inflow continue and are successful.
Accepting these future flows does not mean the system will never experience alarm conditions, but
rather that it is a reasonable risk for the Town to accept. Power outages can occur for extended period
while demand continues. Debris around an impeller can significantly reduce pump performance.
Pumps and electrical components can fail unexpectedly. All these conditions can lead to alarm
conditions and potentially sewer back-ups and discharges.
XC:
Steve Metzger, P.E, LaBella Associates, D.P.C.
Wes Pettee, LaBella Associates, D.P.C.