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20130323 Peer Rev Ltr 09242013 ENGINEERiNG.PLANNING,ENVIRONMENTAL SCIENCES 1019 39th Avenue SE,Suite 100 Puyallup,WA 98374 T.253.604.6600 E 253.604.6799 www.parartietrix.com September 24,2013 PMX No. 216-1781-031 Ph 09 Ms. Karen Bennett City of Yelm 105 Yelm Avenue West Yelm,WA 98597 Re: Prairie Park Stormwater Review Dear Karen: We have finished our review of the Prairie Park Stormwater Renovations plan set,as requested on Tuesday, September 17, 2013. Below are our review comments: Comment Sheet/Page Reviewer's Comment No. 1. GN-01 Please revise note 9.A under SJC Alliance General Erosion Control Notes to read "No more than 100 feet" per City of Yelm Development Guidelines Section, 6.160.D 2. DT-01,SD Please provide a Construction Entrance Detail (per City of Yelm Civil Plan Sheets Checklist), and show where construction entrances will be located on the plans. 3. SD Sheets Please provide existing topography, as well as spot elevations of proposed grading plan at each site to ensure adequate drainage. 4. SD Sheets The same linetype is used for different features in the base map, making it difficult to determine existing conditions. Please revise base map for clarity,and add existing features to Legend. 5. SD Sheets Please check all pipe length labels.According to Note 5 under SJC Alliance Storm Drainage Notes, pipe lengths are called out from center of structure to center of structure.This does not appear to be consistent in the plans. 6. SD Sheets Please revise structure labels to include SD pipe invert, diameter, and direction. 7. SD Sheets Please add/revise callouts to more clearly explain which SD pipes and structures are to remain, and those that are to be plugged. 8. SD Sheets Please revise infiltration gallery detail so that filter fabric is wrapped around all sides of gallery. �.��.�r��.��:�� ���w��.,�.,��. �.�.,A���..�k.�� �.���,���aa"��-`�'g ����.�����,�� � ��' �;����,..�::� � Ms. Karen Bennett September 24,2013 Page 2 9. SD Sheets Please revise infiltration gallery detail so that the space between the top of the filter fabric and the finished grade refer to the provided restoration detail. 10. SD-01 Please revise Trench Restoration detail so that cement conc. pavement layer is in accordance with City of Yelm Standard Detail 4-10,Trench- Pavement Restoration Detail. 11. SD-02 and Please revise Pavement Restoration detail so that Class B ACP layer is in SD-03 accordance with City of Yelm Standard Detail 4-10,Trench-Pavement Restoration Detail. 12. Drainage Stormwater Treatment was not addresses in the 1992 DOE Manual in a Report manner that is consistent with current State of Washington standards. The computations should be revised to follow the 2012 Stormwater Management Manual for Western Washington as prepared by Department of Ecology. 13. Plans/Drainage A Tributary Area Map should be provided depicting both the entire Report drainage area that is being removed from the Prairie Park Development. 14. Plans/Drainage Existing pre-development contours of the Prairie Park development Report should be provided as assurance that the bottom elevation of each infiltration gallery is below any fill that could have been placed during construction. 15. Drainage Rationale for the statement"The proposed infiltration trenches will not Report p.4 contain perforated pipe" should be provided. If you have any question please feel free to contact me at our office at 253-604-6600. Sincerely, PARAMETRIX c��'��l� G� Brian Bunker, PE Project Manager BB:Ie