4816 HARBOR LN 2016-01-01 MF Import

.� Letter to Joe Johnston Prcject No. 9463-001 July 29, 2008 Page 4 waters should be directed to the drainage system in the street to the east of the house. No water should be directed by piping to the slope. If it is not physically possible to discharge water to the street, small areas that remain should be dispersed as close to the house as possible, typically through splash blocks. Storm water infiltration should not be attempted. Overland dispersion is the recommended technique for dealing with storm water r�noff that cannot be directed to the storm system in the street. The second triggering activity is fill placement over the top of the slope. This fill placement not only i�cludes soil, but yard waste and other debris. It is a common practice to dump yard waste and other debris over a steep slope. Any yard waste and other debris that has been dumped over the slope should be removed from the slope and disposed off the site. The practice of dumping over the slope should be discontinued. CONCLUSIONS and RECOMMENDATIONS The proposed project is to replace the existing decks on the residence with new decks that have a slightly larger configuration. Foundation support for the new decks is expected to be similar to the existing decks. It would consist of individual pad footings supporting the deck posts. With the proposed increase in deck sizes, the pad footings may be located slightly closer to the steep slope. However, this distance is expected to be so small that the behavior of the slope is unlikely to have any significantly different performance expectation on their foundation support. Since decks are porous structures that permit rainfail to drain through the gaps in the boards, there is no collected storm water to dispose of. Additionally, the decks act as energy dissipators for the rain drops, thereby reducing the meteoric impact erosion of the ground beneath the deck, similar to a tree cover. With the subject decks being above the ground their current distance, there appears to be sufficient light to maintain a grass or other low vegetative ground cover on the ground surface beneath the decks. This will further maintain erosion resistance and reduce the probability of storm water runoff concentration which could impact the steep slope areas. J. KEITH CROSS, P.E. a35e izi" Avenue SE, Bellevue. Washington 98006-4425 U//- % �//