HomeMy WebLinkAbout24IWC11-375 Maple Ave-Applicant's Response to Engineering Comments 1-15-25Page 1 of 3 CLA-7767F
CLA Engineers, Inc. | 317 Main Street, Norwich CT 06360 | 860.886.1966 | www.claengineers.com
January 15, 2025 Ms. Stacey Radford, Zoning & Wetland Officer Montville Town Hall 310 Norwich-New London Turnpike Montville, CT 06382
RE: Proposed Trailer Storage Facility 375 Maple Avenue and Route 163 Montville, Connecticut CLA-7767F
Dear Ms. Radford: CLA Engineers has prepared the attached responses to address comments received from Boundaries, LLC dated January 14, 2025.
Please feel free to call me at our office or email me at dhayward@claengineers.com with any questions or comments. Very truly yours, CLA Engineers, Inc.
Darren Hayward, P.E.
CLA Engineers, Inc.
Civil Structural Survey
317 MAIN STREET NORWICH, CT 06360 (860) 886-1966 (860) 886-9165 FAX
Page 2 of 3 CLA-7767F
CLA Engineers, Inc. | 317 Main Street, Norwich CT 06360 | 860.886.1966 | www.claengineers.com
STAFF TECHNICAL REVIEW COMMENTS:
COMMENTS FROM TOWN CIVIL ENGINEER (BOUNDARIES LLC) DATED JANUARY 2, 2025
Stormwater Modeling 1. Per page 60 of the Stormwater Quality Manual, “If flow rates and velocities at critical downstream locations increase by less than 5% from the pre-developed condition, and no existing structures are adversely impacted including exceedance of freeboard clearances
and allowable flow velocities, then no additional analysis is necessary. Otherwise, the project proponent should redesign the stormwater quantity controls on the site and/or propose corrective actions to the impacted downstream areas.” Please certify for the project record that the increased runoff rates from the site will result in less than 5% increases in flow rates and velocities at downstream locations and that no existing structures will be adversely impacted. Response: Existing flow rates upstream of Robertson Road were obtained using the online StreamStats application from USGS (included as Appendix D in Stormwater Management Report). The proposed increase in run-off rates for each storm event are compared below:
Site Wide Peak Flow Rate (CFS)
per Storm Event
2-Year 10-Year 25-Year 50-Year 100-Year
Existing Streamstats Flow (cfs) 326 608 805 978 1170
Prop. Additional Flow (cfs) 0.51 1.28 1.43 1.30 0.93
Proposed Increase (%) 0.16% 0.21% 0.18% 0.13% 0.08%
Increase in flow rate is not expected to exceed less than one-half a percent for any storm event. We are not aware of any capacity issues with any downstream structures and it is our opinion these minor increases will not have adverse impact to freeboard clearances or allowable flow velocities. 30-inch Drain Relocation 2. Please provide the proposed top of frame elevation for the downstream manhole.
Response: The top of frame elevation is 235.0 and has been shown on the plans.
Page 3 of 3 CLA-7767F
CLA Engineers, Inc. | 317 Main Street, Norwich CT 06360 | 860.886.1966 | www.claengineers.com
3. Please specify the proposed rip rap gradation for the spread apron on the site plans. Per the information provided in the stormwater report rip rap used at the drainage discharge
should be “standard.” Response: The proposed rip rap gradation has been called out on the plans. 4. Please incorporate a hood in the proposed catch basin if feasible and acceptable to the Response: A hood has been called out to be installed in the proposed catch basin.