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<br />2, Future development condition hydrology with existing facilities, <br /> <br />3. Future development condition hydrology with on,site detention and <br />proposed improvements, <br /> <br />a schedule of proposed improvements was recommended which included regional <br />detention ponds, channel improvements, and upgraded road crossings. A portion <br />of the recommended improvements are shown on Figure 6 on the following page <br />and summarized below. <br /> <br />A regional detention pond is proposed for construction in order to reduce the peak <br />historic flows within the Tri,Town Drainageway, The regional detention pond <br />would be located immediately south of the Town of Frederick on existing <br />agricultural land. The pond would need to contain approximately 146 acre-feet of <br />storage during a 100 year storm event and require approximately 60 acres of land <br />to be constructed, The beauty of the detention pond site is that it could be used by <br />the communities for multi purposes such as soccer fields as well as storm water <br />detention. The existing concrete box culvert under Main Street is proposed to be <br />incorporated into an improved detention pond outlet structure, Because of water <br />rights consideration, storm water retention was not contemplated as an option. <br /> <br />The communities have concluded that the regional detention pond site south of <br />Frederick is the best location and are moving ahead with purchase of the land. The <br />purchase of land is being accomplished by the Town of Frederick by a 1/2 cent sales <br />tax as documented in Appendix 3. The land purchase price is anticipated to be <br />$350,000. The communities have viewed this project as an opportunity to enlarge <br />the existing detention pond and provide a regional multi,use amenity for all to <br />enjoy. From the numerous drainage master plans that have been prepared over the <br />last 10 years, there have been no other ideal locations within the basin to place this <br />regional detention pond. The 1,25 Corridor Master Drainage Plan Godding <br />Hollow and Tri-Town Basins SOllth ,Veld COllllt}, also chose this site for the <br />regional detention pond. <br /> <br />Preliminary Geotechnical Analysis: <br /> <br />In December 1999 Terracon drilled two soil bore holes in the vicinity of the <br />proposed regional detention pond as documentated within Appendix 4. Soil borc <br />hole TB,3 was located in the vicinity of the pond embankment and the soil consists <br />of topsoil, lean clay with sand, claystone and siltstone. The coefficient of <br />permeability of TB,3 at a depth of 4 feet was found to be 2.9E,06 <br />centimeters/second. Soil bore hole TElA was located in the vicinity of the pond <br />bottom and the soil consists of topsoil, lean clay with sand, sandstone and siltstone. <br />The coefficient of permeability of TBA at a depth of 4 feet was found to be 8. 6E, <br /> <br />16 <br />