HNTB Releases Storm Sewer Plan
(posted 10.31.07) Complete storm and sewer separation is HNTB's recommendation to solve the sewage backup in basements on Gerrard Avenue. According to HNTB Engineer John Duncan, the project cost to rehabilitate the area from 21st Street east of Lynhurst Drive to Dry Run Creek south to 16th Street is estimated at $2.7 million. He said the plan is designed to cover a 10 year 1 hour storm event. Duncan said the storm events that result in sewage backup cause about $6,000 damage per resident and about $2,000 for surface water damage. His calculates the area as suffering about $100,000 in damage after major storm events. He said there is also the unquantifiable cost of the emotional duress and the potential of being exposed to diseases while being exposed to sewage. He admitted the damage figure was not perfect, but based on assumptions made by talking to insurance companies. Duncan said recommendation number two, a partial separation, would send storm water into the combined sewer storm drain on 16th Street. Either system would require a detention pond to hold the water for a five year or ten year event. Board member Paul Maves said total separation would help the residents the most instead of building bigger tanks at the waste water treatment plant to hold the storm water for treatment. Duncan explained they did not have a cost estimate of how much it would reduce the long term control plan that is required by IDEM to be able to treat storm water before passing through the system during certain rain events. He agreed with Maves that it would reduce the size of the two clarifier tanks. Norm Berry, waste water treatment plant superintendent, asked if the detention pond could be eliminated if Dry Run Ditch was improved to eliminate bottleneck flows. He thought the town would benefit more from a clean out project than by building a detention pond. Maves said the Dry Run Ditch clean out project as been on-going for five years. The project was canceled last year because the bids exceeded the estimated cost of $300,000. Duncan said it depended upon how significant the improvements are to the ditch whether a detention pond is needed or not. Street Department Commissioner Wendell Walters said after the last big rain the water volume was not moving through the pipes after the new inlets were added to 22nd and Lynhurst Drive Coppertree Apartment area. He said the department began to investigate and discovered the 40" pipe and 60" pipe were clogged with debris. He said it was necessary to clean them to keep the water moving west, away from the 21st Street and Gerrard Avenue that gets inundated with surface water from that area during the heavy rains. Walters estimated it would cost $15,000 and he would like to get started on the project. Storm Water Management Board President Bill Golay said there are not sufficient funds to cover the project because of the money spent for HNTB to do the computer modeling to study the storm water and the hydraulics in the area. He said he would take the request to the council for funding. The board said they would review the recommendations for their Nov 15 meeting at 5 pm at the town hall. |
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