Letter - Remedy Footing Drain Connection 2017-11-06.pdfLM
Lovell-Sauerland and Associates, Inc.
19217 36th Avenue West, Suite 106
Lynnwood, Washington 98036
Phone: 425-775-1591
LSAEngineering.com
Engineers / Surveyors / Planners / Development Consultants
City of Edmonds Engineering Division
121 51h Avenue N
Edmonds, WA 98020
Re: Brackett's Corner, 8010 — 2121h Street SW (Building Permit #20160598)
Engineering Site Plan Construction Evaluation Letter
November 6, 2017
LSA No. 5537
Per Mr. Chris Lyon's request, LSA is pleased to provide the following professional engineering
evaluation of the as -built footing drain and crawl space drainage systems for the Brackett's Corner 14
new homes at 8010 — 212th Street SW.
The engineering drainage and site development plan included the installation of footing drain discharged
into City's storm drainage system at the southwest corner of 801h Avenue W/212th Street SW intersection.
During the course of construction activity, footing drain system for individual building was installed and
connected to the infiltration trench, which was designed for collected runoff from building roof.
Per the "Footing Drain" (attached) prepared by Liu & Associates, Inc., dated September 25, 2017, the
amount of groundwater, if any, to be collected into footing drain of the proposed residence will be
limited. Therefore, the footing drain discharged into infiltration trenches will be acceptable to dispose
water in footing drain.
Since both footing and crawl space drainage systems are now discharging to infiltration trench, even
though all footing and crawl space drainage systems are installed above the groundwater elevation at
441.0 (see attached spread sheet), raise of water level within infiltration trenches during storm events
may cause water to backup and overflow into the footing and crawl space drainage systems. Standing
water can either backup and/or seepage into crawl spaces.
In order to prevent and remedy the potential wet footing foundations and crawl spaces situation, a
backflow preventer valve (type approved by the City) is proposed to be installed on the pipe right before
entering the catch basin (typical), which is connecting to infiltration trench. Wrap crawl space pipe at the
entrance with filter fabric (Marifi 140X or equal) to keep sand and fines entering the pipe.
If you have further questions or need additional information, please give me a call at (425) 775-1591.
Sincerely,
John W. Yuen, P.E.
Project Engineer
LIU & ASSOCIATES, INC.
Geotechnical Engineering Engineering Geology Earth Science
September 25, 2017
Mr. Randy Brockway
Pride Ventures
320 Dayton Street, Suite 108
Edmonds, WA 98020
Dear Mr. Brockway:
Subject: Footing Drain
Brackett's Corner
80th Avenue W and 212th Street SW
Edmonds, Washington
L&A Job No. 15-058
You propose to dispose water in townhome building footing drains into infiltration
trenches. It is our opinion that the amount of water in footing drains will be limited and
that it will be acceptable to discharge footing drain water into infiltration trenches.
Yours very truly,
LIU & ASSOCIATES, INC.
J. S. (Julian) Liu, Ph.D., P.E.
Principal
19213 Kenlake Place NE - Kenmore, Washington 98028
Phone (425) 483-9134 - Fax (425) 486-2746
Ground
Roof
Footing
Crawl
Infiltration
Top of
Overflow
Lot
Floor
Drain
Drain
Space
Trench
Rock
Invert
Invert
Number
Elev.
Elev.
Elev.
Elev.
Number
Elev.
Elev.
Elev.
1
448.0
444.4
443.9
443.8
1
445.20
443.70
445.20
Overflow would occur from top of CB #1, rim elev.=446.93
2
448.0
443.7
443.2
443.1
2
444.50
443.00
Overflow would occur from top of CB #1, rim elev.=446.93
3
447.5
443.8
443.3
443.2
3
444.60
443.10
444.90
Overflow route to CB #18, inv.=443.07
4
447.8
444.1
443.6
443.5
4
444.90
443.40
444.90
Overflow route to CB #18, inv.=443.07
5
447.9
445.4
444.9
444.8
5
446.25
444.75
446.25
Overflow route to CB #18, inv.=443.07
6
447.7
444.6
444.1
444.0
7
445.40
443.90
445.40
Overflow route to CB #18, inv.=443.07
7
447.7
444.1
443.6
443.5
6
444.90
443.40
444.90
Overflow route to CB #18, inv.=443.07
8
448.0
445.5
445.0
444.9
8
446.25
444.75
446.25
Overflow route to CB #18, inv.=443.07
9
448.5
444.6
444.1
444.0
7
445.40
443.90
445.40
Overflow route to CB #18, inv.=443.07
10
447.7
444.0
443.5
443.4
11
444.80
443.30
444.80
Overflow route to CB #18, inv.=443.07
11
448.3
444.8
444.3
444.2
12
445.60
444.10
445.60
Overflow route to CB #18, inv.=443.07
12
448.7
445.1
444.6
444.5
13
445.85
444.35
445.85
Overflow route to CB #18, inv.=443.07
13
448.0
445.1
444.6
444.5
14
445.85
444.35
445.85
Overflow route to CB #18, inv.=443.07
14
447.7
445.1
444.6
444.5
15
445.85
444.35
445.85
Overflow route to CB #18, inv.=443.07
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