HomeMy WebLinkAbout23SITE7-69 Fitch Hill Rd-NPUComments 1 052223
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May 22, 2023
Norwich Public Utilities
Attn: Alisa Morrison
16 South Golden Street
Norwich, CT 06360
Subject: Hydraulic Modeling/Analysis Letter Report for
69 Fitch Hill Road Development
Montville, CT
Dear Ms. Morrison:
Per the request of Norwich Public Utilities (NPU), Dewberry Engineers Inc. (Dewberry) has prepared this
letter report summarizing the results of the hydraulic analysis of the subject project utilizing NPU’s
existing water system computerized model. The information provided by your office was used to
estimate the system’s ability to deliver adequate flow for fire protection and evaluate any service
impacts that the proposed development may impose on the existing water system.
Hydraulic Analysis
The proposed development is at 69 Fitch Hill Road and is expected to consist of three individual
warehouse/storage type buildings with two at approximately 19,920 sf each and one at approximately
6,000 sf. There is also a planned addition of approximately 4,566 sf for office space to the existing
building located on the property. Below is a screenshot of the site plan taken from the set of drawings
prepared by Green Site Design LLC that was provided to Dewberry to perform the analysis.
To serve the new development, it is being proposed to extend the existing 12‐inch main at the
intersection of Old Fitch Hill Road and Fitch Hill Road up to the entrance of the property. From here, a
new 8‐inch main is proposed to connect to the new 12‐inch main and extend up into the property to
serve the new buildings and site (see attached Figure 1). It is proposed to construct the new
development in three (3) phases with each phase to include a new building as shown above. From an
Phase I Building
Phase 2 Building
Phase 3 Building
Norwich Public Utilities
Alisa Morrison
May 22nd, 2023
Page 2 of 3
email sent to NPU from Green Site Design LLC on 05/19/23, the estimated domestic water usage and fire
flow needs for the new development is as follows:
Domestic Water Usage:
Phase 1 Building:
600 GPD /8 hours = 75 GPH/ 60 minutes = 1.25 GPM x 6 safety factor = 7.5 GPM
Phase 2 Building:
1,992 GPD /8 hours = 249 GPH/ 60 minutes = 4.15 GPM x 6 safety factor = 25 GPM
Phase 3 Building:
1,992 GPD /8 hours = 249 GPH/ 60 minutes = 4.15 GPM x 6 safety factor = 25 GPM
Total Domestic Peak Water Usage for Phases 1, 2 & 3 = 57.5 gpm
Fire Flow Needs:
Phase 1 Building:
Needed Fire Flow (NFF) = 1,063 gpm
Phase 2 Building:
NFF = 1,700 gpm
Phase 3 Building:
NFF = 1,700 gpm
Total NFF for Phases 1, 2 & 3 = 4,463 gpm
To evaluate the impacts of the proposed Fitch Hill Road development to NPU’s water system, we first
added the proposed water main connection and supporting infrastructure to the model. We then
imposed the estimated total peak water usage of 57.5 gpm for all 3 phases to the development to
identify any possible loss in system pressure in the adjacent area. As shown in attached Figure 1, under
existing maximum day demand conditions, system pressure at the intersection of Old Fitch Hill Road and
Fitch Hill Road was predicted to be 94 psi. With imposing a peak demand of 57.5 gpm within the
development, system pressure at the intersection of Old Fitch Hill Road and Fitch Hill Road was
predicted to remain at 94 psi. This suggests that the existing system infrastructure within the area of the
development can supply the domestic water needs of the proposed development.
We then estimated the available fire flows at the proposed connection to NPU’s water system under
existing maximum day conditions without the development and with the estimated peak water usage
for the development while maintaining a system residual pressure of 20 psi. As shown in attached
Figure 1, without the development, the available fire flow at the connection to the proposed
development as represented by junction NJ‐1285 was predicted to be about 2,800 gpm. With adding the
proposed development’s peak water usage to the model, the available fire flow at junction NJ‐1285 was
predicted to be about 2,750 gpm. Given this minimal reduction in fire flow, the model suggests that
NPU’s water system should be able to maintain similar fire protection within the area when serving the
proposed development.
Lastly, we estimated the available fire flows that NPU’s existing water system can provide at three
locations along the proposed 8‐inch water main being installed to supply each of the buildings under
existing maximum day conditions while maintaining a system residual pressure of 20 psi. As shown in
attached Figure 1, the available fire flows at the three modeled locations as represented by junctions
Norwich Public Utilities
Alisa Morrison
May 22nd, 2023
Page 3 of 3
FHJ‐002, FHJ‐003 and FHJ‐004 were predicted to be 2,300 gpm, 2,075 gpm and 2,050 gpm, respectively.
Based on the modeled results, NPU’s existing water system should be able to effectively deliver the
individual fire flows needed for each building.
Conclusions
Based on the results of our analysis, the proposed development at 69 Fitch Hill Road is predicted to have
minimal system impact on service pressures and available fire flows within the area. The model also
shows that NPU’s existing system is predicted to satisfy the estimated individual fire flow requirements
for each of the buildings to be constructed in phases. As such, the existing system should be able to
support the domestic and fire protection needs of the proposed development.
It should be noted that in the email dated 05/19/23, the total needed fire flow for the fully phased
development was indicated to be 4,463 gpm which represents the total needed fire flow for each
individual building on the property. This would be a worst‐case scenario as it assumes that all three
buildings would be on fire concurrently. The NPU should verify how the fire flow needs of the fully
phased development should be assessed with the Norwich Fire Department. Based on the results of the
analysis, the water system was predicted to provide a maximum available fire flow of 2,300 gpm which
is obviously less than the noted total of 4,463 gpm.
Depending on the final criteria to be used for determining adequate fire protection, additional fire
protection measures such as building sprinkler systems, or a fire pump may need to be installed by the
developer. Given the type and size of buildings to be constructed, it is likely that these structures are
already being provided with sprinkler systems which may reduce the needed fire flows to be provided
on‐site by NPU’s water system.
If there are any questions or further evaluation necessary, please feel free to contact me at
pcalderazzo@dewberry.com
Sincerely,
Peter Calderazzo, PE
Associate
Attachments
Figure 1 – 69 Fitch Hill Road Development
4412
8
1228
8
812121288
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8 8HY1373HY1372HY0918HY0917HY0916HY0921HY0920HY1432PHY1411HY0919Fitch Hill Rd
Old Fitch Hill RdAnn Av
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Frances St
Marie Ave
Pal
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S
t
Tory Dr
Desjardins DrRichard Brown DrLSJ-1882LSJ-1674LSJ-1672LSJ-1671LDJ-1101LDJ-1100LSJ-817LSJ-144LSJ-143LSJ-1286NJ-1285Fitch
Hi
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ump
#1
NP-1648
NP-168 NP-167NP-18
9
3
NP-1892FHPSP-01NP-2548
NP-2545NP-2543NP-28261.55 gpm0.41 gpm0.00 gpm0.25
gpm1.63 gpm0.80 gpm1.59
gpm0.61 gpm1.39 gpm0.00 gpm0.99 gpmLDJ-2002P-157FHPSJ-01FHPSP-02P-29
4
Fitch
Hi
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#2FHPSP-03FHPSP-04ROUTE 395
114 psi74 psi66 psi38 psi62 psi54 psi70 psi75 psi
52 psi93 psi81 psi50 psi48 psiFHJ-0010.00 gpm45 psiFHP-001FHJ-00225.00 gpm35 psiFHP-002FHJ-00325.00 gpm22 psiFHP-003FHJ-0042,057.50
gpm19 ps
iFHP-004NODE FHJ-002:AFF @ 20 PSI =2300 GPMNODE NJ-1285:EX. SYSTEM PRESSURE = 94 PSI;W/ PEAK FLOW OF 57.5 GPMSYSTEM PRESSURE = 94 PSIPHASE 1:NFF = 1063 GPMUSAGE = 7.5 GPMPHASE 3:NFF = 1700 GPMUSAGE = 25 GPMPHASE 2:NFF = 1700 GPMUSAGE = 25 GPMNODE NJ-1285:W/O DEVELOPMENT:AFF @ 20 PSI = 2800 GPM W/ DEVELOPMENT: AFF @ 20 PSI = 2750 GPMNODE FHJ-003:AFF @ 20 PSI =2075 GPMNODE FHJ-004:AFF @ 20 PSI =2050 GPMFIGURE NO. 1NORWICH PUBLIC UTILITIES69 FITCH HILL ROADPROPOSED DEVELOPMENT SYSTEM ANALYSISDATE: MAY 22, 2023SCALE: 1" = 250'DEPROPOSED 8"WATER MAINPROPOSED 12"WATER MAINEXTENSIONPROPOSEDBUILDINGADDITIONPROPOSED PHASE 3BUILDINGPROPOSED PHASE 2BUILDINGPROPOSED PHASE 1BUILDING