REV04320 - Laserfiche WebLink

Home Browse Search

r EXHIBIT G (Cont'd) • CONSLUSIONS AND RECOhIhIEfdDATIONS A drainage study was prepared for the proposed Ralston Quarry site in response to the Jefferson County Board of Adjustment Resolu- tion. The purpose of the investigation was to make observation of the existing drainage patterns of the site, calculate the storm run- off for existing and quarry conditions and to make recommendations to minimize the impact of the quarry on the environment. The con- clusions and recommendations of the foregoing report are: a) The existing drainage patterns of the site are such that storm runoff is basically in a sheet flow form and does not enter Long Lake at a concentrated point except for the Swale on the south. The low intensity, frequent storms produce very little runoff. In the natural state, no apparent drainage problems were observed. b) The quarry operation, during the period where little or no reclamation has taken place, would increase the potential • storm runoff for the immediate basin tributary to Van Bibber Creek over historic conditions if a detention pond were not provided. However, the grading of the quarry will keep storm water originating from the quarry area from entering Long Lake or Ralston Reservoir. c) By constructing a detention pond to collect the storm runoff from the quarry site, the peak runoff rates from the immediate area will be reduced to values near the historic rates. The effect of the quarry on the drainage environment at Van Bibber Creek will be muted by the detention pond such that historical and quarry conditions runoff is very nearly the same. d) The quarry site can be graded during excavation and during reclamation to properly drain the site and thusly essentially eliminate the quarry's impact or effect on the drainage • environment.