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Memorandum
Date: January 14, 2008
To: Grant Beck, Wal-Mart Stores, Inc.
From: Mike Beach
Subject: Wal-Mart Store #3705-00; Yelm, Washington
Revised STEP Tank Design
Dear Mr. Beck:
As you are aware, the consultant hired to complete the original STEP tank design has been reviewing [he
current system in place at the request of [he City and based on a peer review report provided by
Parametrix dated, December 12, 2007. The consultant has reviewed the peer report and existing (lows
into the system. A revised design has been completed and is being presented to the City for review.
The proposal to improve the existing STEP tank system will include installing a new 5,000 gallon Xerxes
tank in series with the existing 8,000 gallon tank. This connection will be made via an 8" PVC pipe sloped
at 2 % . The separation between the tanks will essentially act as the required baffle wall since the large tank
will collect the solids and the smaller (new) tank will hold the effluent. Please note the new tank will be
installed with tank hold-down straps and concrete ballasts as necessary for buoyancy.
Per the DOE Sewage Design Criteria Manual, a STEP tank shall have a minimum of 24 hours of storage
within the tank except for tanks that are connected to a power transfer switch with an emergency
generator. Therefore to meet this requirement, we are proposing to connect the STEP tank pump to a
transfer switch that will connect the pump to the generator currently on the Wal-Mart property. This
connection will be made as part of the installation of the new tank.
Attached you will find revised STEP tank details, a plan sheet showing the location of the proposed tank,
and design calculations based on the current flows into the existing tank.
Please contact me a[ (360) 78&9500 if you have any questions.
Cc: Allen Seay; Wal-Mart Stores, Inc.
Alton Lewis; Bird Construction
Sherlita Kennedy; Yelm Wal-Mart Store Manager
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CONTRACTOR TO F19_D
VtRI=Y;OCA~ION PRIOR
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NEJu 5000 GA~~LOU'
AIL' TAR.K
EXISIIU'G STEW I ".UK
STEP TANK SECTION
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~ECTIOfe OF P,OG- DRu!U
I FF~D~R TO 3E -EM?ORARII_Y
REMOVEC DU~R'NG
~D.STALLA-100. OF -ANK.
NOT
1) S'EP iA~UR R~ER LIDO TO
MATCH EXISTI~VC TRADES.
2) STEP TANK TO 3~= 10~ST01FD
WITH HOLD GOWNS AND
CONC~~FTF BAV-AST PE4
M A,Vl1FD~ l1RLRS REQUREMFN TS.
31 NFW TO SANK TO BE
INSTAU ED ~? SANE 7~VAIIOGi
C~ ~UISTING SAN'.
WAL-MART STORE #3705-00
~ ~ ~ ~ ~ ~ YELM, WASHINGTON EX-1
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