05-0601 Review No 3 040507
City of Yelm
Community Development Department
105 Yelm Avenue West
P.O. Box 479
Yelm, WA 98597
April 5, 2007
Robert Connolly
Skillings Connolly Inc
5016 Lacey Blvd. SE
Lacey, WA 98503
RE: The Hutch Subdivision – SUB-05-0601-YL
Third Review of Civil – Site Construction Documents
Mr. Connolly:
The City of Yelm has completed the initial review of the proposed subdivision. Your application included:
Construction Plans dated March 5, 2007
Stormwater Report dated March 1, 2007
Landscape Plans no date
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. In an effort to
expedite the review of this project we have sent this project out for Peer Review. The following comments need to be addressed before the plans may be approved for construction. The
comments are summarized below:
Storm Drainage Report:
Storm Drainage Report Section 3 – The infiltration rates provided are for Basins A and B only. An assessment of the infiltrative capability of Basins C and D also need to be provided.
These rates should be used for calculation of required volumes. This information was not provided in the resubmittal.
Storm Drainage Report Appendix C – The geotechnical report provided does not contain infiltration information for Basins C and D. An evaluation of the expected infiltration rates needs
to be provided for these basins. This information was not provided in the resubmittal.
Storm Drainage Report Appendix B – Please provide pipe sizing calculations. Although you have indicated that the largest drainage area is 5.45 acres and it has a flow of 2.17 cfs and
the pipe capacity is actually 2.73 cfs for a 12 inch pipe at 0.5% slope, no computations have been provided to support these numbers. A computation of the drainage area, flow for the
drainage area, and pipe capacity should be shown for each pipe. This should take in to account the cumulative effect of the flow to the pipes. In other words, the cumulative drainage
area may be 5.45 acres for the pipe, but the cumulative flow is computed based on the individual drainage areas and associated times of concentration. Even if all pipes are adequately
sized, calculations demonstrating this need to be provided? As the City will take
over the maintenance of this drainage system, it shall be demonstrated that the pipes can handle expected flows. Please note, a 25 year event can be used for pipe sizing. This information
was not provided in the resubmittal.
Construction Plans:
Sheet 5 of 29:
The plans have a retaining wall to be designed by others. The design needs to be submitted and approved.
Sheet 28 of 29:
The level spreader as proposed will not control water as it exits out of the stormwater pipe. Another method needs to be examined.
The ponds must be fenced with 4’ black chain link and 15’ access gates.
Sewer Departments Review:
Mountain View Road stormwater catchbasins are shown over the existing sewer system. Please resubmit a design that does not have this conflict. Your design still has catchbasins located
directly over the existing step sewer line.
The City has noticed a signification number of sewer Carson boxes being installed in the back yards of the houses. We are requiring them to be moved to the side or front yards so the
step tanks may be connected. This affects lots 41, 53, 81, 94, 105, 106 and 113. Please relocate the Carson boxes to the front yards.
Water Department Review:
Any Pocket Parks, street frontage on Killion Road and Mountain View Road with irrigation meters and double check valve assemblies. Please show the irrigation meter for Mountain View
Road.
All the fire hydrants need to have a six inch gate valve for the fire hydrants at the main. Please show them on the plan view.
Landscape and Irrigation Plan:
Describe how the two open space tracts on the north side of plat will be improved, i.e. recreational equipment.
42, 445 square feet of open space is required.
Type I landscaping is required along the south property line. Preferably an 8’ foot masonry fence.
Please provide the City of Yelm street tree planting detail.
Provide the species of the trees that are being planted.
Misc Information:
An Underground Injection Well Application is required for both stormwater galleries. This may be acquired through the Department of Ecology. It is your responsibility to get this approval.
The City of Yelm does not issue this notification.
The mailbox locations must be shown on the plans. Please contact the Yelm Postmaster for locations and approval. Note: The City of Yelm only allows the “CBU” type boxes with in the
subdivisions. No single mail box clusters are allowed.
Please review and revise the plans to address the above referenced comments. When you are ready to resubmit the project please contact me before you resubmit and we can discuss
the process or requirements. The project engineer is required to 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