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John Oliver & Associates, Inc. <br /> Civil Engineering <br /> • <br /> Land Surveying 580 Dodge Avenue, Elk River,MN 55330 <br /> Land Planning • (612)441-2072 • Fax:441-5665 <br /> August 22, 1996 <br /> Mr. James Charest <br /> 2819 119th Avenue <br /> Coon Rapids, MN 55433 <br /> RE: Grading and Drainage Plan - Elk River, MN <br /> Dear Mr. Charest: <br /> We have completed your Grading and Drainage Plan, and have enclosed 10 prints of the <br /> plan. Also enclosed is the wetland delineation performed by Dan Wing of Eco Systems <br /> Engineering, Inc. <br /> • The drainage of the site will have minor changes from existing. The soils located at the site <br /> are Hubbard Sandy Loam, Hubbard Loamy Sand, and Isanti Loamy Fine Sand. These soils <br /> are all in Hydrologic Group A (see attached soils map). The central low area collects runoff <br /> from 12.79 acres at present. For the proposed conditions this low area will collect the <br /> runoff from 12.87 acres (See the Enclosed drawings depicting the drainage areas). The low <br /> area has the following stage storage relationship: <br /> ELEVATION AREA INCREMENTAL VOLUME <br /> ft acre VOLUME (acre-ft) acre-ft <br /> 867 0 0 0 <br /> 868 0.06 0.03 0.03 <br /> 870 0.99 1.05 1.08 <br /> 871.3 1.77 1.79 2.87 <br /> This low area is not landlocked, it would release at an approximate elevation of 871.3 into <br /> a wetland delineated on the grading plan to the north east. <br /> The runoff volume will increase due to adding additional impervious areas, the existing <br /> • Curve Number for the area flowing to the low area is 50, and the proposed Curve number <br /> is 51 (See the enclosed worksheets used for calculating the Curve numbers). <br /> Offices in Elk River Sr Burnsville <br />