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05-0770 Review No. 2 012008 City of Yelm Community Development Department 105 Yelm Avenue West P.O. Box 479 Yelm, WA 98597   January 20, 2008 Jeff McInnis Petra Engineering 535 Dock Street, Suite 213 Tacoma, WA 98402 RE: Samantha Ridge- City of Yelm Project No. PRD-05-00770-YL Second Review of Civil Construction Documents Mr. McInnis: The City of Yelm has completed the second review of the proposed Planned Residential Development. Your application included: Transmittal Comments regarding Initial Review letter from City of Yelm Full Size Plans Drainage and Erosion Control Report Operation and Maintenance Plan 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. I would recommend we have a meeting to discuss these comments before you revise and resubmit the plans. Drainage and Erosion Control Report: The report does not include the correct predevelopment storm event summary. It appears that the post development summary was included with the wrong header. The stormwater report does not include the disturbed pervious area of the project. Please include this area in the calculations. The report shows 3 stormwater basins included in the basin map. Please include information on all stormwater basins. This should include calculations and assumptions that have been made with these basins. The report should include a level pool routing that includes the routing of the post developed storms and the predeveloped release rates. It appears that each storm has been routed in the hydrograph starting at elevation 330.00. Typically the 10 year storm level should be starting at the top of the 2 year storm. The report should include the orifice sizing calculations. The stormwater design should include an overflow for the pond that has been sized to accommodate the 100 year design flow. The City of Yelm conditions of approval require you to get a Department of Ecology Discharge Permit for discharging to Yelm Creek. In the past Department of Ecology has questioned the Vortechs treatment device. It currently does not meet the DOE requirements of basic treatment. It is approved for pretreatment only. Please provide conveyance calculations for the level spreader piping. It appears that there are many utilities under the stormwater pond. We can not maintain these pipes when they are under the pond. Sewer Plan Review: The number of tanks planned for this project (29) must be reduced. Please use larger tanks. This same comment was made on the 1st review when only 15 tanks were planned. The tank sizes need to be shown on the drawings. The step tank sizing must be in conformance with Department of Ecology Criteria for Sewer Works Design Manual. A 12” sewer main is planned for future capacity (not shown on the drawings). This new main was to be installed next to the existing main. Please contact City to discuss installation coordination. Please include all updated sewer details pertaining to this plan. Sta. 4+92.50 needs an end of line clean-out. For clarity, all pressure lines going from the tanks to the main are called “service lines”, not force mains. Please show all gravity side sewers. All Pump Control Panels will need to be mounted on remote posts. Please show the location of all service line valve boxes (Carson boxes). Please show the location of hose bibs to enable servicing of the STEP Tanks. A hose bib is required to be within 50 feet of a tank. The reclaimed water line is not labeled on the plan. It appears that there is a utility main running under units 5 and 13 and the stormwater facility. If this is actually the reclaimed water main then you will not be allowed to construct the buildings on top of the main. This may also apply to the electrical easement that is along side of the 20’ utility easement. Stormwater and Grading Plan Review: Please revise stormwater table callouts for type 1 and type 2 catch basins. The storm report states that the roof drains are going to be routed to the stormwater system. Please show the roof drain leaders and connections to the stormwater system. During review of the plans I was not able to find the min 2% call out for the driveways. Water Plan Review: When a property has a reclaimed water main running through it, all of the water meters will need a Reduced Pressure Backflow Assembly installed following the water meter. Sta. 2+17.39 - the sewer is too close to the water main. These must have 10 feet of horizontal separation and 18” of vertical separation. From Sta. 0+54.45, the new water main will need to be run straight to the existing main under Crystal Springs Road. The connection shall be a hot tap to the existing main. The project will need to cut and cap or plug the old main at the gate valve under Crystal Springs Road. The valves shown on the one inch service lines should be Corp Stops, not gate valves. The irrigation shows the backflow assembly before the water meter, this needs to be behind the meter. Please label the water main for removal. I was unable to locate the callout your response refers too. Irrigation Plan Review: Irrigation plans have not been included in the construction drawings. Please submit irrigation plans with the next submittal. Misc Comments: The City of Yelm no longer allows individual mail boxes clusters. Only metal CBU’s are approved for use in City of Yelm. Please remove the old City of Yelm detail and replace with CBU detail from manufacture. This location must also be approved by the Yelm Postmaster. Please submit a signed plan with the Yelm Postmasters’ approval on it. 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 P.E. Development Review Engineer cc. Jack Long, 115 5th Street NE, Auburn, WA 98002