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The 2, 10 and 100 year storm flows from ali pervious graveled areas will <br />be detained in the 51'x30' dry detention pond shown on the DHA drawing, <br />sheet 1 of 1. All three storms from the developed site vvill be controlled and <br />piped out at the natural discharge point to the downstream property as can be <br />seen on sheet 1 of the DHA drawings. A manifold system of nine 4" PVC pipes <br />will drop out only the existing storm flows that existed before development and <br />will act to similate sheet flow. The existing outlet storm flows of 0.05, 0.18 and <br />0.44 cfs will be released only for the 2, 10 and 100 year storms respectively <br />and will not impact the downstream property. In fact, this system will probably <br />help the property owner to the south with more absorption of the quick one-day <br />impact storms by absorbing first storm flows like a spong. <br />The ecology block wall will be brought to within City heighth <br />requirements by removing some of the 3 high wall to 2 high or 4' or less in <br />heighth. The subsurface drain that is shown on the nort�west side of the site <br />will be rerouted due south to outlet at the southwest comer where it will drain <br />southeast to the natural out�et swale where it did before. The existing duplex <br />lot will have an outlet for each of three infiitration trenches as shown on the <br />DHA plan. It will go due south under the existing block wall at the lowest <br />discharge point of 538.00 and will provide relief from any infil oveflow. It <br />should be noted that portions of the duplex lot are tower than the natural <br />discharge point for this site and would have and will still naturally pond near <br />the existing duplex building. Utility services are immediately available from <br />108th St SW mains although the developer pl�ns no building at this time. <br />The developer has stated that they will not store vehicles or store oil <br />products on site. As a resuit no storage tanks will be necessary on any of the <br />sublots. Also because the impervious surface is only 2 areas of 20'x20' for <br />driveway entrance and is less than 5000 sq ft, no oil separation facility is <br />needed. <br />7 <br />