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04-0148 civil review 1 031805 City of Yelm Community Development Department 105 Yelm Avenue West P.O. Box 479 Yelm, WA 98597   March 18, 2005 Brian Mathews Skillings and Connolly, Inc 5016 Lacey Blvd. Lacey, WA 98503 RE: Oak Ridge Subdivision (Willow Glenn 3) SUB-04-0148-YL Initial Review of Civil – Site Construction Documents Mr. Mathews: The City of Yelm has completed the initial review of the proposed single family subdivision. Your application included: Construction Documents dated February 14, 2005 Stormwater Report dated January 31, 2005 Landscape Plan undated and received February 24, 2005 We have reviewed the plans for compliance with the City of Yelm Development Guidelines, the DOE Stormwater Manual and general standards of civil engineering practice. The following comments need to be addressed before the plans may be approved for construction. Our comments are summarized below: Cover Sheet (sheet 1 of 14): The Willow Glenn 3 name has been replaced with Oak Ridge Subdivision. Add the Conditions of Approval to the cover sheet. Remove the “individual” from the step sewer callout under project data. Horizontal, Demolition and Erosion Control Plan (sheet 2 of 14): Add the horizontal control information to the plan. This should show the centerline information, curve data, radius returns, right of way widths, etc. Grading and Stormwater Plan (sheet 3, 4 of 14): Label whether the stationing for the catch basins is to center of structure or flowline. Stormwater piping shall not be shallower than 0.5%. Call out all stormwater pipes, lengths and slopes. The cross slope on Cascadian Ave Se needs to be 2.0% min from the crown of the roadway to the flowline. At the intersections the 2.0% should be carried through along the Cascadian centerline. The curb radius should have spot elevations shown at the point of tangent, point of curvature and along the curve showing the elevations. All ADS N-12 piping shall have at least 1.5 feet of cover over the pipe. If this can not be met please change the pipe type to ductile iron. Drainage Plan (sheet 5 of 14): The swale/filter strip needs to be between 2.0% and 4.0% in slope. The pond sections do not appear to match the plan view. A wall is shown on the west side of the pond and not in the profile. The setbacks for the stormwater pond are 10’ from all property lines and tract lines. In this instance we are willing to wave the 10’ setback from the flood plain line because no development is going to be occurring at that location. The setbacks are 10 feet from the property line to the top or toe of slope depending on the topography (beginning of the berming or cutting of existing ground). The max. water surface should be 1 ft below berm height. (free board between MWS and berm) The rock level spreader is no longer approved for use in Yelm due to the labor intensive maintenance. The end of the perforated pipes will need to have cleanouts installed for maintenance. Roadway Sections and Details (sheet 7 of 14): Label the typical street section with the street type and add another street section for Middle Road. Water and Sewer Plan and Profile (sheet 8, 9 of 14): The water valves at callout no. 1 should be shown on the northeast and northwest legs of the tee. The water valves at callout no. 2 should be shown on the northwest and southwest legs of the tee. The water valves at callout no. 5 should be shown on all legs except northeast leg of the cross. The tap at the existing 10” watermain in Middle Road shall be a hot tap. Road A connection to the southeast needs to have an 8” gate valve and 2” blow off installed at the end. Road A connection to the Northwest will be required to install an 8” gate valve to test against. This should be located at the connection to the existing waterline. Please show the irrigation meter and DDCV required for the irrigation system on Middle Road and the stormwater facility. The end of the sewer lines need to have end of line cleanouts installed. See City of Yelm standard details. The sewer line located in Road A will need to connect to the existing line located in the Prairie Creek Subdivision. The sewer pipe sizes need to be revised. The pipe in Road A and the cul-de-sac’s should be 2” in size. Cascadian Ave sewer should be 3” in size until the cross in Road C and 2” all the way to Road A. The sewer connection shall be a live tap of the existing main. Water and Sewer Details (sheet 10, 11, 12 of 14): The air-vacuum detail is not the current detail. The elbow needs to be extended to 12” above the finished grade. Remove main line pig port detail from sheet. Change the dimension from 3ft to 2ft on the sewer detail 7-25. Frontage Improvements Plan and Profile (sheet 13 of 14): Show curb flowline slope and cross slope for the roadway widening. Is the storm pipe in Middle Road going to be PVC or ADS? Please clarify. The storm pipes must be a min of 0.5% or steeper. Where is the stormwater going from between Sta 48+00 and Sta 50+00? The sawcut line for the widening of the roadway shall be at least 8 feet from the existing asphalt edge of the roadway. The stormwater pipe appears to be in conflict with the existing water line. How is the min horizontal clearance going to be met? The note on the plans should read “Contractor to replace all disturbed roadway sections to the City of Yelm standards and guidelines” not in kind. Please add a catch basin to relocate the storm pipe running from CB 18 to CB 11 at least 7.5 feet from the edge of right of way. Street Lighting (sheet 14 of 14): The street light plan appears to be complete. However the standard in Yelm is to have the street lights hard wired to PSE’s circuits. This eliminates the j-boxes, meters and controllers. The City will be taking over ownership of the street lights when the plat is finaled and the current design does not comply with the maintenance program. After review the street light locations the city request that the poles be relocated per the redlined drawings. Middle Road will be required to have street lighting installed. Stormwater Report: The infiltration rates appear to be too high. Using the formula from the 1992 DOE manual states, that the h is the column of water above the infiltrative surface. The formula is assuming that the column of water is all water not a void ratio of 40%. The column of water that you propose is only 40% water creating the additional head on the infiltration surface. The city is not discounting the validity of the multiplier however it appears to be too large for the intended application. Please contact Community Development Department to further discuss this. Landscape Plan: See attached redlined drawing. For questions please contact Tami Merriman at 360-458-8496. Conditions of Approval: Please review the conditions of approval to verify you have met all the requirements of the hearings examiner. Please review and revise the plans to address the above referenced comments. When the project is resubmitted you will need to submit 4 sets of plans, 2 stormwater reports. The project engineer should include a written response with the resubmittal, indicating how all the review comments above have been addressed or responded to. This will significantly expedite our review of the project. If you have any additional questions or comments please do not hesitate to call or contact me at jimg@ci.yelm.wa.us. Community Development Department Respectfully, Jim Gibson Development Review Engineer cc. enc.