04-0148 Request for information 010305
City of Yelm
Community Development Department
105 Yelm Avenue West
P.O. Box 479
Yelm, WA 98597
January 3, 2005
Brian Mathews
Skillings Connolly
P.O. Box 5080
Lacey, WA 98503
Dear Mr. Mathews:
The Community Development Department has reviewed your application for the Willow Glenn Phase III Subdivision, and has determined that additional information is necessary to complete
the review. Staff has performed a completeness review, and has found items missing or that do not meet the intent of City regulations.
The basin summary has been reduced from 7.79 acres to 4.04 acres. Where has the remainder of the basin area been routed too? When changing from native ground cover to lawns the area
being converted must be included in the basin calculation.
Please show the time of concentration map for the 15 minute interval or use 5 minutes. The time of concentration should not be less than 5 minutes.
Please include all the stormwater modeling calculations. Many of the printouts are missing from the stormwater report.
The infiltration rate of the calculations appears to be too high. Using 15 in/hr (.000347 ft/sec) multiplied by square footage of gallery, I come up with:
EL. 327 = 0.3123 cfs
EL. 328 = 0.3574 cfs
EL. 329 = 0.4025 cfs
EL. 330 = 0.4494 cfs
Also by showing an infiltration rate above the 330 elevation the model believed that infiltration is still occurring above this elevation. Your model shows elevation 332 infiltrating
at 1.62 cfs which reduces the volume required.
When berming around the pond the stormwater manual requires a min of 3’ horizontal top of the berm and 1 foot of freeboard from the top of the berm to the 100 year water elevation.
The min. setback from all property lines and tracts is 10’.
The review period has stopped until the following information is submitted and deemed complete. The review period will begin 14 days after receipt of this additional information unless
you receive written notification additional information will be required.
If you have any questions please feel free to give me a call. I can be reached at (360) 458-8438.
Respectfully
Community Development Department
Jim Gibson
Development Review Engineer