25978 CORRESPONDENCE
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lNLAND PAClFIC ENGINEERING, INC.
November 18, 1994
Chris Reich, E.I.T.
Spokane County Engineers Office
w. 1026 Broadway Ave. ~~0-V 2 2 1994 ~
Spokane, WA 99260
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RE: Autumn Crest Fourth Addition ^ - I.P.E. Project No. 94308
Chris
Enclosed please find the following informadon for the above referenced project.
- Revised Road Plans (1 set mylar, 1 set sepia)
- Revised Storm Drainage Analysis (1 copy)
- Red-lined check prints.
- '208' Lot plans. (1 copy)
Please review the enclosed plans for approval, have Bill sign both sets and retum the sepia
set to us when they are approved. '
Included are the following responses to selected review comments.
7) The curb radius has been changed to 30 . The property retum radius was left at 20'
at the direction of Dave Berto since the lots had already been closed and the property
return did not affect the geometry of the cul-de-sac.
12) The taper length was calculated at 90 feet using a 6-foot taper and a design speed of
30 mph. The minimum af 100 feet was used per County standards.
16) "R" value tests have been conducted and the results are enclosed. According to my
calculadons, an "R" value of 53 would require a section of 2" AC on 8" CRST. I
have specified this section on the plans but we would like to get another test done
prior to paving per Howard Consultants' recommendations.
21) While the use of .25 as the runoff coefficient for Basin R(und) does not affect the
conclusion of the drainage analysis or the size of the required drainage facilities, it is
not consistent with past analysis. We are making the change on this project for the
sake of expediency. However, a C of .25 for an undeveloped basin in sandy or
gravelly soil is not reasonable since that is the same number that one would use for
1/4 acre developed density. The value of .10 that was used initially in our analysis
which conesponds to lawn is much more realistic in my opinion.
707 West 7th • Suite 200
Spokane, Washington 99204
509-458-6840
FAX: 509-458-6844
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22) The calculations for Basin M as submitted show that the peak flow occurs in the
impervious portion of the basin. We therefore ran the Bowstring on the impervious
basin only. You are correct in stating that the peak storage requirement occurs when
analyzing the entire basin. The calculations have been updated and the drywell type
has been revised accordingly.
Sincerely,
INLAND PACIFIC ENGINEERING COMPANY
,
Steven P. Soltys, P.E.
SPS/wp
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- INEERING - TRANSMITT~►L
I N LAN D PAC I F I C E N G F~: (509)458-684a
707 W. 7th Avenue, Suite 200 Spokane, WA (509)458-6840
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ECT PE-1570~89 E I`~`fON-`~~`:~:~~~~:~::::~~'~~~
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Description:
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■ Blueline Prints p Copy of Letter 0
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* Original Drawing Cf Contract Documents 0
* Report ■ Declaration ofi Cov. 0 C~
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No. Copies Description
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1 . Red lined check prints ~ Easements Added) ~
~ Revised Finale Plat (Dnana _,e
Purpose ~
rmation ■ Review & Comments 0 Per Your Request
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❑ Written Approval 0 Signature & Return ❑
Remarks
Dave - Enclosed please find the Revised Final Plat for the above
referenced prol'ect. 1 only added the Drainage Easements and some
minor changes as requested. Also enclosed are the proposed
.
nants for review. Please advise if these meet with
Declaration of cove
your approval for getting signatures. If you need any additionaly
•nformat• ~r~ please do not hesitate to contact this office. Thanks for your
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assistance on this project.
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INLAND PACIFIC ENGINEERING - TRANSMITTAL
707 W. 7th Avenue, Sulte 200 Spokane, WA (509)458-6840 Fax: (509)458-6844
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POKAN E COUNTY ENGINEER
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ATTENTION. Dave Bert
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OJECT . PE-1570-89 '
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Description:
■ Xerox Prints 0 Copy of Letter ■ 1l~-dated Plat Qortificate
* Original Drawing 0 Contract Documents 0
* Report 0 Declaration of Cov. 0
No. Copies Descriptlon
2 Revised Final Plat
1 Un-dated Plat Certificate
Purpose
■ Information ❑ Review & Comments ❑ Per Your Request
* Written Approval ❑ Signature & Return 0
Remarks
Dave - Enclosed please the revised final plat and an updated plat
certificate on the above referenced project. I am ready to have the mylar
made. if you have any questions, or comments please contact this
office as soon as possible. Thank you for your assistance on this
project.
Signed: _ DE~ ~ c 2 7 1995
~o""►trti' ENGfNEFR
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