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Home My WebLink AboutANALYSIS LETTER REPORT 5-22-2023 Page 1 of 3 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 8 8 8HY1373HY1372HY0918HY0917HY0916HY0921HY0920HY1432PHY1411HY0919Fitch Hill Rd Old Fitch Hill RdAnn Av e Frances St Marie Ave Pal m e r S t Tory Dr Desjardins DrRichard Brown DrLSJ-1882LSJ-1674LSJ-1672LSJ-1671LDJ-1101LDJ-1100LSJ-817LSJ-144LSJ-143LSJ-1286NJ-1285Fitch Hi l l P 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 l l P um p #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