Agenda - Council - 10/22/1991 - Laserfiche WebLink

Home

· RESTORATION OF TURF SURROUNDING THE SIDE SLOPES OF THE POND Following construction of liner, side slopes of the pond will need to be graded and turf restored to prevent erosion of the side slopes into the pond. The Homeowners Position: At their request, the homeowners were supplied with a copy of the technical specification which the developer's engineer prepared to solicit a bid from the contractor. The homeowners have interpreted a section of this specification such that the contractor would place sod to within twenty feet of their houses. The Contractor's Position: The contractor intends to restore all disturbed areas of the side slope with topsoil, seed and mulch up to areas of established vegetation. In most cases, it would appear that such disturbed areas would not need to extend to the top of the pond side slope. Tlae City's Position: The City would define the pond as beginning at the top of the side slope. Tuff establishment by seeding and mulching to this point would be acceptable. In interpreting the intent of the agreement, the belief is that the developer needs to provide a pond which is not subject to erosion. The acceptable quality of that turf might be considered similar to that required for the establishment of vegetation behind newly poured curblines to prevent excessive mn-off of material into the streets. · WHEN WILL THE COMPI.F. TED POND BE FILLED WITH WATER Construction specifications require permeability tests on the clay liner to insure water tightness of the pond. The developer had anticipated allowing the pond to fill naturally with mn-off and precipitation. It would be possible to fill the pond from the City water supply, however, the cost for providing the water would be in the neighborhood of $2,000. The Homepwncr'~ Position: The homeowners feel the pond should be filled upon completion of the construction this Fall. Mrs. Fessler indicated she had spoken with an individual at Mn/DOT who suggested that should a clay liner dry out, fissures in the clay could destroy the impermeability of the liner. The City's Position: The City feels that water is included in the definition of "pond". In addition, unless a soils engineer would specifically state that shr/nkage of the clay over the winter period would not be a problem, the City would insist on pond filling from a technical aspect also. The Developer's Position: The developer would prefer to fill the pond following construction only if that were the recommendation of the soils engineer for the purpose of protecting the liner. In addition to the above issues, several questions were directed regarding this pond. Below is a summary of those questions and City responses. · During storm events, when water fills in the pond to a level above the clay liner, will there be an elevation of the local groundwater which might increase the potential for wet basements? The groundwater in the area is known lower than 879 since there is no evidence of water in the bottom of the rough grade pond. The basement elevations of the houses along the pond are approximately 886, which would be higher than the ultimate water level of 885. It is the opinion of the City Engineer that groundwater level, even at high water conditions, would not cause wet basements.