Agenda - Public Works Committee - 02/19/2008

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(NWL) of the pond and elevation of the liner installation (862'), and there was evidence of liner remnants in the grass at the base of the wall. Property monuments were also observed in a couple of locations pounded through the liner. The City Attorney was contacted fot his opinion as to the use of Arcon's escrow funds to further investigate and resolve the issue. He stated that the funds currently held by the City are consistent with the Development Agreement and are for inspection purposes only. The previous securities held to insure installation and warranty of the subdivision improvements have been released. Observations: There appears to be consensus from all that there is indeed a problem with the liner, and the ponds ability to retain water. Arcon seems reserved to the fact that something needs to be done to remedy the problem, and is willing to investigate options with the homeowners. A couple of specific ideas were discussed; they included spot repair of the liner at known/suspected breach locations, and the introduction of a chemical sealer (Seepage Control) into the pond. City assistance (if directed to do so) throughout this process could include filling the pond and maintaining the norinal water level for a couple of weeks (if necessary). The City received a letter from Arcon on January 28, 2008 requesting release of their escrow funds for this project. Since this has been an on-going topic at the Committee meetings, and due to the fact that no agreement has been reached on a resolution to the problem, staff wanted to make you aware of the request and is looking for some direction as to the release of these funds. It is anticipated that discussions between Arcon and the residents will continue throughout the winter months and a plan can be developed for implementation in the !spring that would correct the problem with the pond liner. City staff will need to be included in these talks, and any subsequent agreement reached, as this pond is part ofthe City stormwater system and is encumbered by drainage and utility easements. One concern the City has with the potential introduction of the chemical sealant, Seepage Control, is the effectiveness of this chemical in reaching the leak(s) at the base of the pond.' The liner has an 18" - 24" sand cushion on top of it and our concern is that the chemical will seal the voids in this sand, thus stopping the loss of water from the pond, but not reach the actualleak(s) themselves. The City is responsible for maintenance of this pond and when dredging in undertaken at some point in the future the possibility exists for disturbance to this sand layer, and potential liability for the City ifthe sealed layer is breached and water elevations begin to drop. Recommendation: Staff recommends release of the developer escrow funds, and continued dialog with Arcon and the residents to resolve the issue. Reviewed By: Director of Public Works/Principal City Engineer City Engineer PW: 2/19/08 4