2082_001.pdfDispersion Trench for Wall
and Footing Drains
No Scale
lnstall Straw \Äåttle
on dou¡rslope side until
vegetation established
Existing Slope
Construct trench along contour of hill 20 feet from toe
of slope so that pipe does not emit concentrated
discharge at any one location and trench disperses
overflow evenly along trench line.
4-oz geotexti
cover
s
4" dia. PVC
perf pipe, cap
ends of pipe.
3/4"clean crushed gravel
20'min.18"
vegetated path
Notes:
Layout for dispersion trench must be verified by geotechnical engineer prior to commencing excavation
Dispersion trench must be inspected by geotechnical engineer prior to covering pipe
and after installation of straw wattle with erosion control apron.
For footing drains, dispersion trench does not need a catch basin. Top of trench may be topped with
thin layer of topsoil (less than 8") provided that Mirafi 140N Filter fabric is used to separate drainage
rock from soil. Trench should be at least 10 feet in length.
Connect footing or wall drains to dispersion trench by means of 4-inch PVC (non perforated) with min. slope
oÍ 1l4" per foot of pipe length.
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DAILY FIELD REPORT
ÏIIE CATTICROTIP
Ger¡technlcal Consulting
PO Box 30759
Seattle, WA 98L13
206.s25.5097
Permit:
Address:
Date:
TGG Job #
Client:
Contractor:
Field Rep:
BLD 20L906L0
7415 Braemar Dr
8/6/201e
2025-3
Mirel Sinclair
Somerset Gardens
Paul Stoltenberg
Construction Operations:Dispersion Trench
Description of Activity:
Contractor completed installation of back of wall drains per plan and connected stubout south of
lowermost planter to dispersion trench. Dispersion trench constructed in general accordance with the
attached sheet as recommended by the geotechnical engineer and called out on the plan. Trench consists
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capped at both ends laid level within the upper portion of the trench. Pipe covered with fabric to separate
the topsoil from the drainage zone. TGG engineer verified that spreader trench was constructed per
recommendations. Asked contractor to leave pipe visible with fabric for inspection by City Engineer.
Contractor excavating behind block wall on east side to install drainage zone which will weep through the
wall face of the planters. All walls less than 3 feet in retained height per city requirement.
Contractor will need to reshape the grade and amend the soils with mulch per City engineer requirements
prior to final inspection. Contact TGG Engineer when all soils have been amended with compost and
planting is completed for final nspection.
mbsincinc mcast.net Submitted by:Paul L Stoltenberg, P.E
Project Geotechnical f ngineerken@somersetÊarden.com
milton.thom pson@edmondswa.eov
cc:
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