05-0305 Civil Review 2 042006
City of Yelm
Community Development Department
105 Yelm Avenue West
P.O. Box 479
Yelm, WA 98597
April 20, 2006
Doug Bloom
4200 6th Ave Suite 301
Lacey, WA 98503
RE: Terra Valley Subdivision – SUB-05-0305-YL
Second Review of Civil Construction Documents
Mr. Bloom:
The City of Yelm has completed the initial review of the proposed 41 lot subdivision. Your application included:
Construction documents dated March 22, 2006
Stormwater Report dated December 2005 (same date as original submittal)
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:
Site Plan:
Add all the Hearing Examiners Conditions of Approval to the Cover sheet.
The phone numbers need to be revised. Sewer – 458-8411, Water – 458-8406, Storm – 458-8438.
Additional bulbouts need to be added to the intersections of this subdivision. See redline plans for locations.
An ADA ramp will need to be installed at the end of all dead end sidewalks. This ramp shall connect the end of the sidewalk and the paved surface of the roadway.
Grading and Stormwater Plan:
It appears that you submitted the original copy of the report. I have placed it in the file, if you need it back just call.
Please clarify the following calculations in the drainage report:
The storm shed program shows an infiltration bottom area of 850 SF (10’x85’). Using this area and the peak out of 0.8676 CFS from storm shed, calculates to be +/- 44 in/hr. The maximum
allow release rate is 20 in/hr.
The hydraulic gradient calculation you have shown in the report states that you are using 10 in/hr to begin with, and then increase the infiltration rate based on the head above the
bottom of the pond. This calculation is reasonable and is what we have discussed in the passed. However, here you use 794 SF (which is also conservative) pond bottom area at the maximum
elevation of 330’. Using
these numbers the maximum release rate should be 0.238 CFS or 12.09 in/hr.
The numbers need to be consistent throughout the stormwater report. Based on these numbers it appears that the infiltration pond is sized too small. After reviewing this information
please call and we can discuss. If I have made a mistake on the calculation please bring this too my attention also and we can resolve is quickly.
Water and Step Sewer Plan:
This subdivision will be serving sewer to the town homes for Tahoma Terra MPC. Are the town homes still going to be only 16 units? This will determine the sewer main sizing for the
roadway connection to the town homes.
Landscape Plan:
The landscape plan was submitted as part of the 2nd submittal. It is currently being reviewed. I will follow up with a separate letter addressing any comments that may be required.
Please review and revise the plans to address the above referenced comments. After revising the plans per this letter please contact me to coordinate the resubmittal. Given the minor
nature of these comments we may require that you just submit a PDF of the sheets that have been revised. The project engineer should also 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.
enc.