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HomeMy WebLinkAboutDrainage Sanitary Water Narrative Indianapolis, IN | St. Louis, MO | .www.weihe.net | (800) 452-6408 Allan H. Weihe, P.E., L.S. - Founder Drainage, Sanitary Sewer and Water Service Summary Report Storm Water Management Existing Conditions The Bedford Falls site currently drains in three directions. The northern 2/3 of the site drains to the east to the Osborn-Collins Regulated Drain which is an open ditch running along the eastern property line. The Hinshaw-Henley Regulated Drain, which is contained within a 36-inch pipe, also runs across the site from west to east and outlets into the Osborn Collins Drain. The southeast corner of the site drains to the southeast to a rear-yard inlet in the Kingsborough subdivision to the south of the site. As some of the residents in Kingsborough have pointed out, the southeast corner of our site does not drain well and standing water after heavy rains have been an issue. A small portion of southwest corner of the site drains to the southwest to some rear-yard inlets in the Westchase subdivision. Proposed Conditions As part of the development of this project, a stormwater detention pond will be constructed near the northeast corner of the site. A network of storm sewers will be designed and constructed to convey all surface runoff to the detention pond, where it will be detained and released to the Osborn-Collins drain at a release rate consistent with City and County stormwater management regulations. The Hinshaw-Henley Regulated Drain will be relocated and reconstructed along the northern boundary of the project and will discharge into the detention pond. All drainage issues and specifically, the problems with standing water in the southeast corner, will be corrected with these improvements. All construction documents and calculations for the design of the stormwater convenance system, the detention pond and the reconstruction of the Henley-Henshaw Regulated Drain will be prepared in compliance with City and County standards and will be submitted to the appropriate agencies for review and approval. There is a flood zone area on the site associated with the Osborn-Collins Regulated Drain. The flood zone is confined to an area along the channel with a small area projecting westward. The proposed development of the site will avoid impacting the flood zone other than a walking path crossing. A detention pond is proposed adjacent to the flood zone which will outlet through an existing 36” pipe to the Osborn-Collins Drain. Emergency flood routing from the site will be conveyed to the detention pond. The detention pond will have an emergency spillway that will outlet into the flood zone and be conveyed to the Osborn-Collins channel. As part of the site development, the excavated soil from the detention pond will be used to fill in low areas of the site to improve drainage for the project and the surrounding neighbors who have experienced some drainage issues and ponding water in the past. As is required, the proposed drainage improvements account for the drainage from the right-of-way of 146th St. Our preliminary drainage calculations show the developed release rates based on the inclusion of the street and right-of-way therefore increasing our detention requirements and decreasing the discharge from our pond. Other than the area along the eastern boundary of the site which is adjacent to the Osbourn-Collins Drain, the Bedford Falls site is not at risk of flooding. When we prepare our construction plans, the grading of the site Bedford Falls of Carmel Page 2 of 2 W200515 will include emergency flooding routing so that if a storm inlet is clogged by leaves or other debris, water will not back up into houses. Sanitary Sewer Service Sanitary sewer service will be provided to the Bedford Falls project by the Tri-County Regional Sewer Utility (TriCo.) TriCo has indicated that they have the capacity in their system to accommodate the sewage flows from this project. There are two options being considered for connection points to the existing sewer system. The first option is to connect to the south of the site at a manhole along Kirklees Drive in the Kingsborough subdivision. The second option is to connect to a manhole to the east of the site and south of the Ballentrae subdivision. TriCo has indicated that either connection point is acceptable if easements are in place to allow access. Water Service Water service for Bedford Falls will be provided by Carmel Utilities. The utility has a 12-inch water main along the south side of 146th Street across the frontage of the site and a 6-inch line in Birdsong Lane which is stubbed to the property near the SE corner of the site. Connections to both the 12-inch line and the 6-inch line will allow for water to be provided from 2 different directions and provide a loop connection which is desirable for the benefit of the overall water system.