Prelim Drainage Report
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Yelm Retail
Preliminary Drainage Report
April 1997
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PROJECT INFORMATION
Project:
, Prepared: ~
Pr~pared For:
Contact: -
REVIEWING AGENCY
Jurisdiction:
Project Number:
Project Contact:
Yelm Retail Center
Apnl1997
Mlke Edwards
lVl1ke Edwards
PO Box 3800
Lacey, Washmgton 98509
(360) 459-1100
"
City ofYelm
Ken Garmann
DESIGNER INFORMATION,
Prepared By:
Project Contact:
SCA Project Number:
File Number:
SCA Engineering
677 Woodland Square Loop SE
PO Box 3485
Lacey, WA 98509-3485
(360)493-6002
(360)493-2476 FAX
Robert W. Balmelli, P.E.
95031
f:\text\reports\50310416 pdr'
PROJECT ENGINEER'S CERTIFICATION
I hereby certIfy that thIS Prehmmary Dramage Report for Yelm Retail Center m Yelm;
Washmgton has been prepared by me or under my superVISIOn and meets the mtent of
the CIty of Yelm Dramage DeSIgn and ErosIOn Control Manual, unless noted
otherWIse, and normal s~andards of engmeermg practIce I understand 'that the
JUriSdictIOn does not and WIll not assume habIhty for the suffiCIency, SUItability, or
performance of dr~mage facilitIes .desIgned for thIS development.
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Table of Contents
Part 1 Project Description
SECTION 1 - EXISTING CONDITIONS 1
SECTION 2 - PROJECT DESCRIPTION 1 '
SECTION 3 - INFILTRATION RATES/SOILS REPORT 3
"
SECTION 4 - WELLS & SEPTIC SYSTEMS 3
SECTION 5 - FUEL TANKS 4.
SECTION 6 - SUB-BASIN DESCRIPTION 4
SECTION 7 - ANALYSIS OF 100-YEAR FLOOD 4
SF;CTION 8 - AESTHETIC CONSIDERATIONS FOR STORMWATER FACILITIES 4
I
SECTION 9 - DOWNSTREAM ANALYSIS AND FACILITY SIZING 4
SECTION 10 - COVENANTS, DEDICATIONS, EASEMENTS 5
SECTION 11 - PROPERTY OWNERS ASSOCIATION ARTICLES OF
INCORPORATION 5
Pa,:t II ,Erosion Cohtrol Plan
SECTION 1 " CONSTRUCTION SEQUENCE AND PROCEDURE 6
SECTION 2 . TRAPPING SEDIMENT 6
,
SECTION 3 - PER~ENT EROSION CONTROL & SITE RESTORATION 7
SECTION 4 - GEOTECHNICAL ANALYSIS AND REPORT 7
SECTION 5 - INSPECTION SEQUENCE 7
SECTION 6 - CONTROL, OF POLLUTANTS OTHER THAN SEDIMENTS 8
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Part III Maintenance Plan
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SECTION 1 - REQUIRED MAINTENANCE
SECTION, 2 - RESPONSIBLE ORGANIZATION
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SECTION 3 - VEGETATION MANAGEMENT PLAN
SECTION 4 - SOURCE CONTROL.
Appendices
Dramage CalculatIOns
FacIhty\Summary Forms ,
SCS Soils Map, Sou Logs, InfiltratIOh Tests
ViCInIty IMap \
Dramage Plan
11
14
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Part 1
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Project Desctlption \
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Yelm Retail Center
PROJECT DESCRIPTION
The format of tlus report follows the outlIne proVIded m the Dramage DeSIgn and
, ~
,ErosIOn Control Manual (DDECM) for Thurston County
SECTION 1 -
EXISTING CONDITIONS
-The 641 acre project SIte IS located m Yelm, Wasillngton, at the corner ofYelm Avenue
and Killian Road. The property IS 9c:cupIed by two houses and a mobile home with grayel
driveways and variOUS outbuIldmgs. The SIte conSIsts of faIrly level topography WIth
relIef varying from 2-10% slopmg from northeast to southwest. See EXIstmg SIte and,
DemohtlOn Plan. I
Offsite Drainage
-
From SCA's, SIte mvestIgatIOn It appears that all eXIstmg on-SIte dramage IS mfiltrated
on-SIte, wluch IS representatIve of the Nisqually class of soils. 'It appears that there IS no
off-SIte dramage onto the property
Existing Drainage Features amJ Environmentally Sensitive Areas
There are no ponds, raVInes, gullies, springs, steep slopes, or other enVIronmentally
senSItIve areas IdentIfied on-SIte or down gradIent of the property All runoff from
eXIstmg features appears to mfilttate on-SIte
GroJlndwater Sensitive Area
The project SIte IS located m an aquIfer senSItIve area based on reVIew of Thurston
County ComprehenSIve Plan Map M-8
SECTION 2 -
PROJECT DESCRIPTION
Project Proponent:
MIke Edwards
Parcel Numbers:
21724130600,21724130500
Total Site Area:
641 Acres
Zoned.
CommercIal
Site Address.
Y~lm Avenue and Killian Road
Required Permits:
- CommerCIal Plat" GradIng, utllity,~ paVIng, buildmg,
plumbmg, ~echamcal, electrIcal, etc.
SCA Engineering
April 1997
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Yelm Retail Center
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SecITownship/Rahge:
SectIOn 24, Townsmp 17 North, Range 1 East, W.M.,
, Thurston County, W A
Legal Description:
(Not mcluded)
The proposed project IS a commerCIal bindIng SIte plan (Chapter 16.32) vested on July 25,
1995 It will convert the SIte from reSIdentIal use to commerCIal use The SIte will be/
cleared of all eXistIng structures and graded to a slope of 2% or less slopIng northeast. A
retaImng wall will be constructed In the south corner as needed. Three bUIldmgs are
proposed buildIng footprmts for wfuch would total 54,800 square feet. ImperviOUS area
will total 5 62 acres or about 88% (see table below) ,
,
/
All phases of the project will Include erOSIOn control measures, SIte cleanng, gradIng,
storm draInage.Improvement~, and roadway and underground utilitIes such as water,
power, samtary sewer, and telecommumc~tIOns. '
Develonment Coverag-e Summary (acres)
ImperVIous Roadway Area.
DIsturbed PerVIOUS Area.
UndIsturbed PerVIOUS lJll-ea.
ImpervIOUS Roof Area.
EXistIng
0.22
5.98
000
0.21
Proposed
4.36
079
000
1:26
A. Stormwater Treatment
Subbasm f( and B
Treatment systems In Subbasms A and B will be compost stormwater filters as
manufactured by CSF Treatment Systems, Portland OR. DeSIgn flow for the SIX
month 24 hour storm IS i 10 cfs In SubbaSIn A and 52 cfs In SubbaSIn B
Sub-BaSIn C and D
,
SubbaSIn C ,and D conSIst of the roof area of the large bUIldIng on the southwest
edge of the property (Lot 3, 4, 5, and 6) and the bUIldIng on the ,northeast corner
(Lot 1 and 2) The roof area runoff will be Infiltrated WIthout treatment 'Per the
Thurston County Manu,al.
SCA Engineering
April 1997
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Yelm Retail Center
i3 Stormwater Storag-e.
BASIN ImpervIOus Roof PerVIOUS Total Storage
Acres Area Acres Acres CuFt
Acre$
, A 2.97 023 038 358 9,980
B 1.39 0 012 151 4,290
C 0 08 0 08 2,400
D 0 023 029 052 980
Totals 4.36 126 079 641 17,650
01
Storage was calculated by consIdermg the reqUIrement to,mfiltrate the deSIgn
I
event m 48 hours and mlillmum storage requIrements per the Thurston County
Manual. Storage will be prOVIded m the medIa VOIds wIthm, mfiltratIOn trenches.
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C Roof Runoff:
All roof runoff will be tIghthned dIrectly mto mdIVIdual undergroulJ.d mfiltratIOn
drywells. See Drmnage CalculatIOns m the Appenchx for calculatIOns of storage
volume reqUIred and prOVIded. ' -
'Value of Remodels in Past 5 Years:
1
NA. Not a remodel proJect.
SECTION 3 -
INFILTRATION RATES/SOILS REPORT
The Soil ConservatIOn ServIce (SCS) soil survey of Thurston County classIfies the on-SIte
soils as Spanaway Soil Senes consIstmg mamly of Spanaway Sandy Gravelly Loam. On-
SIte soil test pItS completed by SCA confirm the Spanaway SCS ClassIficatIOn. CopIes of
the soil logs are mcluded m the Appenchx.
Falling Head PercolatIOn tests performed on-SIte wfucated an mfiltratIOn rate of over
60 mches/hr as shown m appenchx.
A deSIgn mfiltratIOn rate of 20"/hr was used to SIze the storage capaCIty of the
underground mfiltratIOn gallery See Appenchx for soils analYSIS and mfilt~atIOn test
results
, SECTION 4 -
WELLS & SEPTIC SYSTEMS
No on-SIte wells were found dUrIpg our SIte mvestIgatIOn or soils work. SeptIc systems
for the three dwelling uruts will be abandoned accordIng to law
SCA Engineering
, April 1997
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Yelm Retail Center
SECTION 5 -
FUEL TANKS
No on-SIte fuel tanks were located dUring SCA's SIte mvestIgatIOn or SOlIs work. A note
on the plans declares that If such tanks are found, the contractor IS to follow DOE
procedures (WAC 173-160) to abandon.
SECTION 6 -
SUB-BASIN DESCRIPTION
From SCA's SIte VISIt, It appears no off-SIte runoff is tributary to the subject SIte All
ramfall on the SIte appears to mfiltrate on-site Tlus IS tYPICal of the Nisqually
classmcatIOn of soils.
SECTION 7 -
ANALYSIS OF IOO-YEAR FLOOD
,
Our reView of the FEl\iIA FIRM map for the proposed project reveals that there IS no
major stream on-SIte The 'SIte has been Identmed as a Zone C classmcatIOn on the
FEMA FIRM Map .
SECTION 8 -
AESTHETIC CONSIDERATIONS FOR STORMWATER
FACILITIES
All dIsturbed perVIOUS areas will De vegetated and landscaped. Subbasm B compost
filter will be pre-cast, bUrIed and Subbasm A will be cast-In-place above ground or pre-
cast, bUrIed.
SECTION 9 -
DOWNSTREAM ANALYSIS AND FACILITY SIZING
.
Prehmmary calculatIOns for the project stdrmwater storage and treatment systems can
be found m the Appenchx of tlus report. All storm"':.ater runoff will be mfiltrated orr~sIte
,
SCA Engineering
April 1997
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Yelm Retail Center
SECTION 10 -
,
COVENANTS, DEDICATIONS, EASEMENTS
On-SIte dramage facilitIes reqUIrmg routme mamtenance mclude.
. Conveyance swale
. Catch basms and storm sewers
. InfiltratIOn gallerIes (3)
. Inlet structures (3) to mfiltratIon gallerIes
. _ -Two compost leaf filters
. Roof drams
Easements for ::lcce~s to and mamtenance of conveyance, treatment, and mfiltratIOn
facilitIes will be granted to CIty of Yelm. An agreement for facilitIes mamtenance w.ill be
reached wIth the CIty ofYelm usmg the model mcluded m the TCDDECM.
I
CC&R's prepared for the project lIst the mamtenance reqUIrements. A copy of the
completed CC&R's can be supphed to the CIty upon completIOn of the proJect.
SECTION 11 -
PROPERTY OWNERS ASSOCIATION ARTICLES OF
INCORPORA TION
'Because the project will be owned by one person, no prqperty owners association will be
furmed I
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SCA Engil)eering
April 199~
Page 5
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EROSION CONTROL PLAN
SECTION 1 -
/
CONSTRUCTION SEQUENCE AND PROCEDURE
Proposed development of the resIdentIal property will Include SIte gradIng and erOSIOn
control measures deSIgned to contaIn slit and soli WIthIn the project boundanes dunng
constructIOn untli permanent erOSIOn control IS m place ErOSIOn/sedImentatIOn control
will be achIeved by a combmatIon of structural/vegetatIve cover measures and
constructIOn practices tailored to fit the SIte
I
Best ConstructIOn Management PractIces (BMP's) will be employed to properly clear and
grade the SIte and to schedule constructIOn actIVItIes. Before any constructIOn begInS on-
SIte, erOSIOn control facilitIes shall first be I.nstalled. The planned ,constructIOn sequence
IS as follows.
,
1 Schedule pre-constructIOn conference WIth the CIty, project engIneer and constructIOn
stakIng surveyor - , ..
2. Construct temporary stabilized constructIOn entrance
3 Install, filter fabnc fenCIng where approprIate and place silt protectIOn around
catchbaSlns '
\ 4. Perform clearIng and grubbIng maccordance WIth the condItIOns of gradIng permIt.
5 MaIntaIn eqUIpment and water supply for dust control.
6 Hydroseed or seed/mulch areas subject to erOSIOn. ,
7 MaIntaIn all erOSIOn ~ontrol facilitIes until the entIre SIte IS constructed and IS
stabilized and silt laden runoff ceases.
8 Keep conveyance systems to mfiltratIOn systems blocked until constructIOn IS
completed ard perman~nt erOSIOn control IS In place and paved surfaces are clean'ed
of constructIOn silt and debrIS
9 Open conveyance systems to InfiltratIOn facilitIes.
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SECTION 2 -
TRAPPING SEDIMENT
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The on-SIte solis belong to the Nisqually soil group and have a shght erOSIOn potentIal
accordIng to the SC~ A stabilized constructIOn entrance shall be Installed at the north
end of the SIte to prevent velucles from track~ng soil away from the dIsturbed areas onto
19th Ave S.E. If sedIment IS tracked off-SIte, sedIment shall, on a daily baSIS, be swep"t
or shoveled from paved surfaces and not washed down Into the roadSIde dItch. The
follOWIng IS a bnef summary of the BMP's used for thIS proJect.
. SeedIng of stnpped areas (hydroseed and seed/mulch) - PrOVIdes soli stabilizatIOn by
plantIng grasses and legumes In areas whIch will remam bare for more than 7 days
where permanent cover IS not necessary or appropnate
SCA Engineering
April 1997
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Yelm Retail Center
· ConstructIOn Entrance - To reduce the amount of mud, dIrt, rocks, etc. transported
onto publIc roads by motor velucles or runoff by constructIng a stab:Q1zed pad of rock'
spalls at entrances to constructIOn SItes and waslung ofbres dUrIng egress.
. Filter fence - To mtercept and retaIn sedIment under sheet flpw cond.1tIOns from I
d.1sturbed areas dUrIng constructIOn operatIOns In order to prevent sedunent from
leaVIng' the SIte, enterIng the dramage system, or damagIng the treatment or
mfiltratIOn system., Filter fences must be prOVIded Just upstre'am of the pomt"(s) of
d.1scharge of runoff from a SIte before the flow'becomes concentrated to decrease the
velOCIty of sheet flows.
The con~ractor should not be allowed to leave dIsturbed areas (that are to be left
unworked for more than 7 days) uncovered durIng the ramy season from November 1 '
through March 31 Straw, mulch, sodd.1ng, hydroseedIng or plastIC covermg should be
used to prevent erosl<;m m 'these areas.
DurIng constructIOn, tl~e contractor will be reqUIred to Install filter fabnc fenCIng and
protect stormwater catchbasms from siltatIOn, as shown on the approved plans as
needed and/or as d.1rected by the project engIneer or CIty mspector
,
SECTION 3 -
PERMANENT EROSION CONTROL & SITE
v .
~ESTORATION
All dIsturbed areas will ,be asphalted, covered WIth a bmldrng or landscaped WIth grass,
shrubbery or trees
SECTION 4 -
GEOTECHNICAL ANALYSIS AND REPORT
Slopes exceedIng 15% do not eXIst on-SIte, therefore, a geotechrncal analYSIS for slqpe or
soil stability was not deemed necessary Se~ Append1x for a complete soils deSCrIptIOn.
I .
SECTION 5-
INSPECTION SEQUENCE
In add.1tIOn to the normal CIty mspectIOns, the Project (Engrneer shall InSpect the
facilitIes related to stor~water treatmef\t, erOSIOn control, storage and conveyance
durIng constructIOn. At a mIrnmum, the follOWIng Items shall be mspected at the tIme
specIfied. '
1 The erOSIOn control facilitIes shall be Inspected before the start of clearmg and
grad.1ng to ensure t4e followmg structures are m place
a. ConstructIOn Entrance
b Filter FabrIC Fences, If needed
SCA Engineering
April 1997
Page 7
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Yelm Retail Center
2. InfiltratIOn ,facilitIes will. be mspected before and dUrIng constructIOn to msure
that heavy eqUIpment does not compact the mfitratIOn surface Conveyance to
mfiltratIOn facilitIes will be plugged until all trIbutary area IS st~bilized and
paved area IS dea.ged.
3 The conveyance, systems will be mspected after co~structIon of the facility, but
before the project IS completed to ensure the followmg are m workmg order'
a. Road\,Vay Dr~age '
b. Compost Filters
c. InfiltratIOn Gallery
d. Inlet SedImentatIOn ProtectIOn
e Roof Drams
4. The permanent SIte restoratIOn measures should be mspected after landscapmg IS
completed.
A final mspectIOn shall be performed to venfy final grades, ~ettillgs of control structures
and all necessary mformatIOn to complete i EngIneer's ConstructIon InspectIOn Report
Fqrm. These forms must be completed prIor to final pubhc works constructIOn apPI:oval.
,
SECTION 6 -
CONTROL OF POLLUTANTS OTHER THAN.
SEDIMENTS
r
Washout from a concrete truck shall not be dumped mto the storm draIn, or onto soil or
pavement wmch carnes stormwater runoff. It 'can be dumped mto a deSIgnated area to.
be later backfilled or hardened and broken up for msposal mto a dumpster The
Contractor will be reqUIred to deSIgnate a washdown area for eqUIpment and concrete
trucks.
It IS not antICIpated that InSectICIdes, fungICIdes, herbICIdes, rodentIcIdes, etc will be
(
employed In the constructIOn of thIS proJect. No petroleum products should be allowed to
enter the draInage system.
SCA Engineering
April 1997
PageS
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Part III - Malntenance Plan
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Yelm Retail Center
MAINTENANCE PLAN
INSTRUCTIONS
The project SIte contams the followmg facilitIes that will reqUITe mamtenance
\
. Conveyance swale
. Catch basms and storm sewers
. InfiltratIOn galleries (3)
~ Inlet structures (3) to mfiltratIOn galleries
. Two compost leaf filters
. Roof drams -
The followmg pages contam maIntenance heeds for~most of the components that are part
of your dramage system, as well as for some components that you may not have Ignore
the requIrements that do not apply to your system You should p~an, to complete a
checkhst for all system compoQ,ents on the followmg schedule
1 Monthly from November through April.
2. Once m late summer (preferably September)
3 Mter any major storm (use I" m 24 hQursas a gUIdeh~e) Items marked "S" ()nly
U smg photocopIes of these pages, check off the problems you looked for each trme you dId
an mspectIOn. Add comments on problems found and actIOns taken. Keep these
"Checked" sheets m your files, as they will.be used to Write your annual report (due m
May) Some Items, do not need to be looked at every tIme an mspectIOn IS done Use the
suggest frequency at the left of each Item as a gUIdehne for your mspectIOn.
You may call the County for techmcal aSSIstance Do not heSItate to call, especIally If you
are unsure whether a SItuatIOn you have dIscovered may be a problem.
SCA Engineering
April 1997
Page 9
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Yelm Retail Center
ATTACHMENT "A": MAINTENANCE PROGRAM
COVER SHEET
InspectIOn PerIod.
Number of Sheetl? Attached.
Date Inspected.
Name of Inspector'
Inspector's SIgnature
I,
Page 10
. seA Engineering
'April 1997
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Yelm Retail Center
SECTION 1 - 'REQUIRED MAINTENANCE
The dramage facilities will req.mre occasIOnal mamtenance The followmg general
reqmrements are the mllllmum requIrements as set forth m the Dramage DeSIgn and
ErosIOn Control Manual of Thurston County The reqmred mamtenance for a range_o(
typIcal storm dramage facihtIe~ and frequency of maIntenance are as shown on followmg-
pages.
Cost of Maintenance '
Catch basm and storm.
sewer vacuummg:
$200 per ton of material removed. Annual expense
Compost filters:
, $3000 per year to clean or replace med1a and vactor vaults.
InfiltratIOn facilities:
ApprOXimately 10 year We dependent on silt load allowed to
by-pass the treatment system.
SCA Engineering
April 1997
Page 11
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Yelm Retail Center
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Maintenance Checklist for Conveyance Systems (Pipes and Swales)
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Frequency Drainage WORK Problem Conditions to Check For Conditions That Should
System Req'd Exist
Feature
M.S. Pipes Sediment & Accumulated sediment that Pipe cleaned of all
, debris exceeds 20% of the diameter of sediment and debris.
the pipe.
M Vegetation Vegetation that reduces free All vegetation removed so
movement of water through pipes. water flows freely
A Damaged Protective coating is damaged, Pipe repaired or replaced.
(rusted, bent I rust is causing more than 50%
or crushed) deterioration to any part of,pipe.
M I Any dent that significantly impedes Pipe repaired or replaced.
- flow (Le. decreases the cross ,
- section area of pipe by more then,
20%).
M Pipe has major cracks or tears , Pipe repaired or replaced.
allowing groundwater leakage.
M.S Swales X Trash & D'umping of yard wastes such as Remove trash ;:md debris
debris grass clippings and branches into and dispose as prescribed
swale. Unsightly accumulation of by City Waste
. non-degradable materials such as Management Section.
glass, plastic, metal, foam and
coated paper .
M X Sediment Accumulated sediment that Swale cleaned of all
buildup exceeds 20% of the design) depth. sediment and debris so
that it matches design.
M X Vegetation Grass cover is sparse and weedy Aerate soils .and reseed
, not growing or areas are overgrown with woody and mulch bare areas.
or vegetation. Maintain grass height at a
overgrown minimum of 6" for best
stormwater treatment. I
Remove woody growth,
recontour and reseed as
necessary
M X Conversion Swale has been filled in or blocked If,possible, speak with
by home- by shed, woodpile, shrubbery, etc. homeowner and request
owner to that swale area be
incompat" restored. Contact City to
ible use , report problem if not
. rectified voluntarily
A X Swale does Water stands in swale or flow A survey may be needed to
not drain velocity is very slow Stagnation check grades. Grades
occurs. need to be in 1 % range if
possible. If grade is less
than 1 %, underdrains may
need to be installed.
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SCA Engineering
April 1997
Page 12
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Yelm Retail Center
Maintenance Checklist for Infiltration Systems
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Frequency Drainage Work Problem' Conditions to Check For Conditions That
System Req'd Should Exist
\ Feature ,
,
A Storage area X Sediment A soil texture test indicates Sediment is removed
buildup in facility is not working as its and/or facility is ~
system designed ~pabilities or was cleaned so that
incorrectly'designed. infiltration system
I works accordin!;l to
design. A sediment
trapping area is
installed to reduce
sediment transport
into infiltration area.
A X Storage area A soil texture test indicates Additional storage is
drains slowly facility' is not working at it's excavated'and filled
(more than 48 designed capabilities Or was with drain rock. Fine
hours) or incorrectly designed. soil and 'silt is
- overflows removed to improve
drainage. Contact the
City for information on
it's rE;!quirements
regarding excavation.
M X Sediment Any sediment and debris filling Clean out sump to
trapping area area to 10% of depth from design depth.
sump bottom to bottom of
outlet pipe or obstructing flow
into the connector pipe.
One Time X Sediment Stormwater enters infiltration Add a trapping area by
trapping area area directly without treatment. constructing a sump
- not present for settling of solids.
. Segregate settling'
, area from rest of
facility Contact City
for guidance.
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Maintenance Checklist for Composting Filter Systems
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Frequency Drainage Work Problem Conditions to Check For 'Conditions That
System Req'd Should Exist
'Feature
M,S Hydr Capacity X Facility no Overflowing or by passing. FiltE;r treats the design
c longer handles Reduced capacity of infiltration storm event.
the design systems. Infiltra~ion facilities do
- event without not bli~d.
overflows.
A X Replace or backwash
filter medium. Vactor
vaults.
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April 1997
Page 13
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Yelm Retail Center
SECTION 2 -
RESPONSIBLE ORGANIZATION
The Homeowner's Association or representative shall be responsible for the operation and
maintenance' of all on-site drainage facilities.
SECTION 3 -
VEGETATION MANAGEMENT PLAN
All disturbed pervious areas within the site will be landscaped to provide an aesthetically
pleasing environment.
SECTION 4 -
SOURCE CONTROL
Warning signs (e g, "Dump No Waste - Drains to Groundwater") will be placed along
biofiltration swales and at detention pond inlets '
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SCA Engine~ring
April 1997
Page 14
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Yelm Retail Center
APPENDIX A
DRAINAGE CALCULATIONS
The following calculations were based on the requirements contained in the Drainage Design and
Erosion Control Manual for Thurston County, 1994 Edition.
DESIGN AND BASIN INFORMATION SUMMARY:
Site Area:
BASIN ImpervIous Acres Roof Area Acres PervIOUS Acres
Total Acres
A 2.97 0.23 038 3.58
B 1.39 0 012 151
C 0 0.8 0 08
D 0 0.23 0.29 052
Totals 4.36 1.26 079 641
Soil Classification:
SCS soil classification.
Hydrologic Group
Design infiltration rate
Nisqually Loamy Fine Sand
B
>20 inch/hr (falling head percolation test)
Minimum Storage Requirements: (Table 4 1 DDECM)
Minimum storage volume (disturbed pervious)
1,000 cf/ac disturbed
pervious
3,000 cf/ac impervious
Minimum storage volume (impervious)
seA Engineering
March 1997
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Yelm Retail Center
Minimum Biofiltration Swale Requirements: (Section 7 4 1, DDECM)
TABLE 7.2 SUMMARY OF BIOFIL TER DESIGN CRITERIA
Design Element
Biofilter surface area (for 6-month design
storm)
Biofilter length
Criterion
Per impervious acre, 2,000 sf if inflow is
undetained, 500 sf if metered release
50 ft minimum for swales, 10ft minimum for
filter strips
2 ft minimum and 8 ft maximum for swales,
no criteria for filter strips
2" maximum
15ft per second maximum
1 % minimum, 4% maximum
No steeper than 3 1, prefer 5 1
Biofilter width
Design flow water depth
Design flow velocity
Flow line slope
Side slopes
DRAINAGE CALCULATIONS:
Minimum Stormwater Treatment:
To size compost filters, use the 6 month, 24-hour storm volume Using the SCS method (Water
Works by Engenious Systems, Inc), flows developed are as follows
BASIN ImperVIous Roof Area PerVIous Total 6-Month, 2-Year, 100.Year,
(Non-roof) Acres Acres Acres 24- Hour 24-Hour 24-Hour
Acres Runoff Runoff Runoff
cfs cfs cfs
A 297 0.23 038 358 110 2.57
B 139 0 012 151 052 -. 1.23
C 0 08 0 08
D 0 0.23 0.29 052
seA Engineering
March 1997
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Yelm Retail Center
Minimum Stormwater Storage Volume Required.
MINIMUM STORAGE REQUIREMENTS
(Thurston County Manual)
BASIN ImperVIous Roof Area Pemous Acres Total Acres MinImum Storagel
Acres Acres CuFt
A 2.97 0.23 038 358 9,980
B 1.39 0 012 151 4,290
C 0 0.8 0 0.8 2,400
D 0 uO.23 0.29 052 980
Totals 4.36 1.26 079 641 17,650
Note:
1. Min Storage per Table 4.1, Thurston Countv Manual, for infiltration rate of 20 inches ner hour
Stormwater Storage Volume Provided:
INFILTRATION TRENCH DIMENSIONS
Basin Width Depth Length Diameter Volume
Feet Feet Feet Distribution Provided,
Pipe, Inches Cubic Feet
A 14 5 500 12 10,398
B 4 5 540 24 4,518
C 5 5 300 12 2,542
D 7 5 100 12 1,255
seA Engineering
March 1997
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Facilzty Summary Forms
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THURSTON REGION
FACILITY SUMMARY FORM
Complete one (1) for each facIhty (detentlOn/retentlOn, coalescmg plate filter, etc.) on the project
sIte Attach 8 1/2 x 11 sketch showmg locatlOn of facIhty
Proponent's Fac~hty Name or Ident~fier (e.g , Pond A). See Part 6
Name of Road or Street to Access Facd~ty Yelm H~!!hway
Hearmgs Exammer Case Number N / A
Development Rev Project No / Bldg PermLt No N / A
Parcel Number 21724130600.21724130500
Tobe completed by Utility-Staff:
UtlhtyFacihty Number
ProJect Number (mill)
Parcel NumberStatus (num, lch)
0, Known; I>Pubhc, 2 Unknown; 3; UnassIgned
Basmand Subba.Slll.. (num,6ch)
(2ch forbaslIi;2ch for'subbaslll,2chfuture
Responsible.]urlsdlctlOn. (alpha,.lch)
Part 1 - Project Name and Proponent
Project Name. Yelm Retml Center
Project Owner Mike Edwards
Project Contact. Mike Edwards
Address. PO Box 3800. Lacev. WA 98509
Phone. (360) 459-1100
Project Proponent. (if d~fferent) N / A
Address. N / A
Phone. N/A
Project Engmeer Robert W Balmelh, P.E
Firm SeA Engmeermg
Phone' (360) 493-6002
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Part 2 - PrOlect LocatlOn
Sectwn
24
17N
1E
Townsh~p
Range
Part 3 - Type of PermIt ApphcatlOn
Type of perm~t (e.g, Commercwl Bldg):
Other Perm~ts (c~rcle)
DDOFIWHPA
DCOE Wetlands
DFEMA
DShorehne Mgmt
DEncroachment
r5!.JNPDES
o Other
Commercwl Butldm,; SLte Plan
DCOE 404
DDOE Dam Safety
DFloodplmn
DRockery / Retammg Wall
r5!.J Gradmg
Other Agenc~es (Federal, State, Local, etc.) that have had or w~ll remew th~s Dramage Eroswn
Control Plan. N I A
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Part 4 -Proposed Prolect DeSCrlptlOn
VVh,at stream basm ~s th~s proJect m (e.g, Percwal, Woodland).
ProJect S~ze, acres
Zonmg:
Ons~te.
Thompson Creek
641
Commercwl
Res~dentwl Subdw~sLOn.
N/A
Number of Lots.
Lot s~ze (average), acres.
Buddmg PermLt/Commerc~al Plat
Buddmg(s) Footprmt, acres
Concrete Pavmg, acres.
Gravel Surface, acres.
Latt~ce Block Pavmg, acres.
Pubhc Roads (includmg gravel shoulder), acres.
Prwate Roads (includmg gravel shoulder), acres
Ons~te Impervwus Surface Total, acres.
1 26 ac
4.36 ac
5 62 ac
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Part 5 - Pre-Developed Project SIte eharacterlstlcs
Stream through SIte, y/n.
Name
No
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DNR Type
Type of feature thIS facIhty dIscharges to (i.e , lake, stream, mtermIttent stream, pothole,
roadsIde dItch, sheetflow to adJacent prIvate property, etc.)
Swales, Ravmes, y / n.
Steep slopes, (steeper than 15%) y / n.
No
Yes - Less than 5% of
sLte at southeast corner
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Eroswn hazard, y / n.
100 yr Floodplam, y/n.
Lakes or Wetlands, y/n.
Seeps/Spnngs, y/n.
High Groundwater Table, y/n.
Wellhead Protectwn or Aqu~fer
SensLtwe Area, y / n.
No
No
No
No
No
I'
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Yes
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Other Subbasm A Compost Filter
Part 6 - FacIhtv DeSCrlptlOn
Total Area Tnbutary to Fac~hty Includmg Offs~te (acres):
Total Ons~te Area Tnbutary to Fac~ltty (acres):
Des~gn Impervwus Area Tnbutary to Fac~hty (acres):
Des~gn Landscaped Area Tnbutary to Fac~hty (acres).
Des~gn Total Tnbutary Area to FaCLhty (acres).
Enter a one (1) for the type of fac~hty
Wet pond detentwn
Wet pond water surface area, acres
Dry pond detentwn
Underground detentwn
Infiltratwn pond
Dry well mfiltratwn
Coalescmg plate separator
Centnfuge separator
Other Compost Leaf Filter
Outlet type (Enter a one (1) for each type present)
Filter
O~l water separator
Smgle onfice
Mult~ple onfice
We~r
Sp~llway
Pump(s)
Other Infiltratwn trench shared w~th downspout runoff from
butldmg m northwest corner
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Part 7 - Release to Groundwater
Des~gn Percolatwn Rate to Groundwater (if apphcable)
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3 35 ac
3 35 ac
297 ac
o 38 ac
3 35 ac
1
1
1
20 mches / hour
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Other Subbasm A Infiltratwn Trench
Part 6 - FacIhtv DeSCrlptlOn
Total Area Tnbutary to Fac~l~ty Includmg Offs~te (acres).
Total OnsLte Area Tnbutary to Fac~ltty (acres):
Des~gn Impervwus Area Tnbutary to FacdLty (acres).
Des~gn Landscaped Area Tnbutary to Fac~ltty (acres).
Des~gn Total Tnbutary Area to Fac~lLty (acres):
Enter a one (1) for the type of facdLty
Wet pond detentwn
Wet pond water surface area, acres
Dry pond detentwn
Underground detentwn
Infiltratwn pond
Dry well mfiltratwn
Coalescmg plate separator
Centnfuge separator
Other Compost Filter
3 58 ac
3 58 ac
3.2ac
o 38 ac
3 58 ac
1
1
Outlet type (Enter a one (1) for each type present)
Filter
O~l water separator
Smgle onfice
Mult~ple onfice
We~r
Sp~llway
Pump(s)
Other Infiltratwn trench
1
Part 7 - Release to Groundwater
Des~gn Percolatwn Rate to Groundwater (if appl~cable)
20 mches / hour
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Other Subbasm B lnfiltratwn Trench and Compost Filter
Part 6 - FacIhtv DeSCrlPtlOn
Total Area Tnbutary to Fac~ltty Includmg OffsLte (acres).
Total Ons~te Area Tnbutary to Fac~lLty (acres).
Des~gn Impervwus Area Tnbutary to Fac~lLty (acres):
Des~gn Landscaped Area Tnbutary to Facd~ty (acres):
Des~gn Total Tnbutary Area to Fac~hty (acres).
Enter a one (1) for the type of fac~hty
Wet pond detentwn
Wet pond water surface area, acres
Dry pond detentwn
Underground detentwn
Infiltratwn pond
Dry well mfiltratwn
Coalescmg plate separator
Centnfuge separator
Other Compost Leaf Filter
1 51 ac
1 51 ac
1 39 ac
o 12 ac
1 51 ac
1
1
Outlet type (Enter a one (1) for each type present)
Filter
Od water separator
Smgle onfice
Mult~ple onfice
We~r
Spdlway
Pump(s)
Other Compost Leaf Filter
1
Part 7 - Release to Groundwater
Des~gn Percolatwn Rate to Groundwater (if apphcable)
20 mcheslhour
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Part 6 - FacIlItv DeSCrlPtlOn
Total Area Tnbutary to Fac~hty Includmg OffsLte (acres).
Total OnsLte Area Tnbutary to Fac~hty (acres).'
Des~gn Impervwus Area Tnbutary to Fac~lLty (acres).
Des~gn Landscaped Area Tnbutary to FacdLty (acres).
Des~gn Total Tnbutary Area to Fac~hty (acres).'
Enter a one (1) for the type of fac~ltty
Wet pond detentwn
Wet pond water surface area, acres
Dry pond detentwn
Underground detentwn
Infiltratwn pond
Dry well mfiltratwn
Coalescmg plate separator
Centnfuge separator
Other
08ac
08ac
o 8ac
o Oac
o 8ac
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Outlet type (Enter a one (1) for each type present)
Filter
O~l water separator
Smgle onfice
MultLple onfice
We~r
Spdlway
Pump(s)
Other lnfiltratwn trench
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Part 7 - Release to Groundwater
Des~gn Percolatwn Rate to Groundwater (if apphcable)
20 mches / hour
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Other Subbasm D lnfiltratwn Trench
Part 6 - FacIlIty DescrlPtlon
Total Area Tnbutary to FacdLty Includmg OffsLte (acres).
Total OnsLte Area Tnbutary to Fac~ltty (acres).
Des~gn lmpervwus Area Tnbutary to Fac~hty (acres).
Des~gn Landscaped Area Tnbutary to Fac~hty (acres).
Des~gn Total Tnbutary Area to Fac~ltty (acres).'
Enter a one (1) for the type of fac~ltty
Wet pond detentwn
Wet pond water surface area, acres
Dry pond detentwn
Underground detentwn
Infiltratwn pond
Dry well mfiltratwn
Coalescmg plate separator
Centnfuge separator
Other Compost Leaf Filter
o 52 ac
o 52 ac
o 23 ac
o 00 ac
o 52 ac
1
1
Outlet type (Enter a one (1) for each type present)
Filter
O~l water separator
Smgle onfice
Mulhple onfice
WeLr
Spdlway
Pump(s)
Other Compost Leaf Filter
1
Part 7 - Release to Groundwater
Des~gn Percolatwn Rate to Groundwater (if appltcable)
20 mches I hour
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Part 8 - Release to Surface Water (if applIcable)
Thurston
County MSL
ElevatlOn (f)
Empty'
Present DesIgn
Full
o
25
50
100
Volume (cu ft)
000
DIscharge to
Surface
Water (cfs)
00
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Scs sods"Map} Soil ~~gs} Infiltration Te~ts
~-~~ ~,.--:.(,-~ ~--,,-.:.c..---,,- ~~--=""""~~---'-_"__~
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Yelm Retail Center
SCA #95031
Soils Analysis for Stormwater Control Facilities
Date June 1995
SoIls Logged By. Robert W BalmellI
SCA EngIneermg
ApplIcant. Armada RetaIl Company
2001 6th Avenue
Smte #3202
Seattle, WA 98121
SIte DescnptlOn. Yelm RetaIl Center
SOlI Logs (See Dramage Plan for sOli log 10catlOn)
Depth
0" -27"
27" -41"
41" -97"
Depth
0" -23"
23" -44"
44" -98"
Depth
0" -20"
20" -30"
30" -60"
60" -95"
(c: \data \5031605.log)
Test Hole #1
Texture and Color
Black gravely sandy loam
LIght brown cobbly sandy loam
LIght brown cobbly fine sand
Roots to 57", cobbles to 10" diameter
Mottling
None
None
None
Test Hole #2
Texture and Color
Black gravelly sandy loam
LIght brown cobbly sandy loam
GraYIsh very cobbly medmm sand
Roots to 53", cobbles to 10" dIameter
Mottling
None
None
None
Test Hole #3
Texture and Color
Black gravelly sandy loam
LIght brown cobbly sandy loam
Gray cobbly very gravelly coarse sand
LIght brown very cobbly medmm sand
Roots to 48", cobbles to 10" dIameter
Mottling
None
None
None
None
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DOUBLE RING INFIL TROMETER TEST RESULTS
seA #95031
INFILTRATION RESULTS
Test Pit #2
Start (Mln) Stop (Min) Elapsed Time Total Inches Infiltration
(Min) Drop Rate (In/Hr)
1232 1241 9 mln 12" 80"/hr
1243 1251 8 min 12" 90"/hr
Test Depth 93"
Weather CondItIons
OutsIde Temperature
Test Performed By
Test Date
Test Holes Dug By
Sunny
780
Brad Shea
6/1/95
Backhoe
( c:\data\5031602.dri)
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Project Location
SCS MAP NUMBER 20
(110) - SPANAWAY GRAVELLY SANDY LOAM
o TO 3% SLOPE
SCS SOILS MAP
YELM RETAIL CENTER
Job
Number
95031
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SCA
677 Woodland Square Lp SE
PO Box 3485
Lacey, Washington
98503-0485
(360) 493-6002
(360) 493-2476 Facsimile
(907) 279-5929 Anchorage
s. Chamberlain & Associates, Inc.
June 9, 1995
Mary Hanna Murphy
7350 Alonzo Avenue NW
Seattle, W A 98117
Re: Yelm Retail Center
Soils and Storm Drainage
SCA #95031
Dear Mary'
The followmg IS a bnef descriptIOn of our mItlal soils and stormwater control
analysIs for the Yelm Retail eenter proJect.
INFILTRATION RATES/SOILS
The Soil Conservatlon ServIce (SeS) soil survey of Thurston County classIfies the
on-sIte soils as Spanaway very gravelly sandy loam. SeA analysIs of 3 on-sIte soil
test pItS confirmed the SCS elasslficatlOn.
Spanaway soils are very deep, excessIVely dramed soils formed m glacial outwash.
AtypIcal soil profile IS as'follows.
0"-15" Black gravelly sandy loam
15"-20" Dark yellOWIsh brown very gravelly sandy loam
20"-60" Dark y~llowIsh brown very gravelly sandy loam
Spanaway soils are well sUIted for stormwater mfiltratlon systems due to therr rapId
permeability However, care needs to be taken to remove silt and sedImimt from
stormwater to mmllmze cloggmg of mfiltratlOn systems. In admtlOn, the Ctty of
Yelm Dramage Des~gn and Eroswn Control Manual (DDECM) reqUITes cleansmg of
runoff pnor to mfiltratlOn.
Two Double Rmg Infiltrometer tests were performed on test hole #2 to determme the
project site mfiltratlOn rate. An average mfiltration rate of 85"/hr was recorded by
SCA staff. However, the DDECM maxrmum allowed mfiltratlon rate of 20"fhr must
be used for deSIgn.
STORMWATER CONTROL
The proposal IS to develop the 56 acre sIte .for a 53,620 sf grocery and retail shop
buildmg, 4,000 sf bank pad, and 2,918 sf restaurant pad. Access to the proJect will
be from Highway 510 and proposed new Killion Road extenSlOn. Water and sewer
servIce will be prOVIded by City of Yelm.
The completed proJect will create approxrmately 3 69 acres of new rmpervlOus,
roadway and parking area, 069 acres of dIsturbed pervIOUS area, and 1.29 acres of
roof area. Approxrmately 0.23 acres of off-sIte msturbed pervIOUS area and 1.05
acres of off"sIte rmpervIOus roadway area are tributary to the proJect.
ENGINEERING
PLANNING
SU RVEYI NG
.
.
SCA
Mary Hanna Murphy
June 9, 1995
Page 2
On-sIte Development eoverage Summary
Off-sIte dIsturbed pervIOUS
Off-sIte rmpervlOus roadway area.
ImpervIOus Roof Area.
ImpervIOus Roadway Area.
DIsturbed PervIOUS Area.
UndIsturbed PervIOUS Area.
Totals
EXIstmg
o 11 ac
o 18 ac
o 24 ac
o 23 ac
o 00 ac
6.19 ac
6.95 ac
Proposed
o 23 ac
1. 05 ac
1.29 ac
3 69 ac
o 69 ac
0.00 ac
6.95 ac
A. Stormwater Treatment:
Stormwater runoff from Highway 510, proposed :K.llhon Road extenslOn and
new parkmg lot areas will reqUITe treatment. Acceptable types of treatment
facilitIes are blOfIltratlOn swales, fIlter stnps, wetponds, and wetva'ults. As
an example, If blOfiltratlOn swales are used, a total of 9,480 sf of treatment
(bl{jfIltratlOn) area IS requITed to meet the mml1llum treatment standards of
the eIty ofYelm DDEeM.
Stormwater runoff from proposed buildmg roofs does not reqUITe treatment
pnor to dIscharge mto the groundwater Therefore, all roof stormwater WIll
be tIghtlmed drrectly to the SIte's mfIltratlOh facilitieS.
B Storm water Storage.
Stormwater runoff will likely be stored and mfiltrated on-sIte Via mfIltratlOn
facilitIes. Types of mfiltratIon facilitIes mclude, but are not mmted to, open
retentIon ponds, underground mfIltratIon dram rock gallenes, and
underground mfIltratIOn vaults.
Usmg a 20"/hr mfIltratIOn rate and Table 4.1 of the DDEeM results m a
requITed stormwater storage volume of 19,010 cf. If a rock filled gallery IS
used for storage, the volume of drarnrock requIred to store 19,010 cf at a 3 1
VOId ratio would be 63,367 cf. In companson, an open retentIon pond would
need to be 100' x 100' x 4' deep to accommodate 19,010 cf of storage volume
WIth appropnate freeboard and sIdeslopes.
Please gIVe me a call at (360)493-6002 If you have any questIOns.
Smcerely,.
s. CHAMBERLAIN & ASSOCIATES, INC.
tw- t>> /JLJt/)
Robert W Balmelh
ProJect Engmeer
RWB/jl
Enclosure
(c: \corres\5031606.ltr)
ENGINEERING
PLANNING
.
.
SURVEYING
SCA
DRAINAGE CALCULATIONS
The following calculatIons are based on reqUITements con tamed m the Dramage
DesIgn and ErOSIOn Control Manual (DDECM) for Thurston County, 1994 EmtlOn.
DESIGN AND BASIN INFORMATION SUMMARY:
Site Area (Developed Condition):
Total off-sIte msturbed pervIOus
Total off-sIte rmpervIOus area.
Total rmpervIOus roadway area.
Total rmpervIOus roof area.
Total msturbed perVIOus area.
Total sIte area.
o 23 ac
1.05 ac
3.69 ac
1. 29 ac
0.69 ac
6.95 ac
Soil Classification:
SCS soil classnicatIOn
HydrologIc Group
SIte mfIltrabon rate (desIgn)
SIte mfIltrabon rate (field tests)
Spanaway gravelly sandy loam
B
20" Ihr
85" Ihr
Minimum Storage Requirements:
Reference.
Table 4.1 DDEeM
Minimum storage volume (msturbed pervious)
1,000 cf/ac msturbed pervIous
Minrmum storage volume (impervIous)
3,000 cf/ac ImpervIOus
SUB-BASIN CALCULATIONS:
Minimum Stormwater Treatment Area Require~:
Reference
ehapter 7, SectIOn 7 4.1, DDEeM
Assume use of bIOfiltratIOn swales.
Per SectIOn 7 4.1 of the DDECM, bIOfIltratIOn swales shall be mmImum 50 ft
m length and shall be lined with 6" of sandy loam topsoil.
ImpervIous roadway/parking area = 3.69 ac + 1.05 ac = 4.74 ac
RequITed treatment area = 2,000 sf/ac (4.74 ac) = 9,480 sf
ENGINEERING
PLANNING
.
.
SURVEYING
seA
Other optIons are available for stormwater treatment. The followmg
methods of storm water treatment will be investIgated durmg prelnnmary
and fmal phases of deSIgn.
. BIOflltratIOn swales
. BlOfiltratIOn stnps
. Oil/water separators
. Compost fllter umts
. Wetvaults
. Wetponds
Minimum Stormwater Storage Volume Required.
Reference
Thurston eounty DDEeM, ehapter 4, Table 4.1
AppendIx II, InflltratIon Test Results
Assume use of underground dramrock mflltratlOn gallenes.
Two Double Rmg Inflltrometer Tests were performed on-sIte The average
mfiltratIon rate was 85"/hr Therefore, a maXllllum desIgn mfiltratIon~ rate
of 20"/hr must be used to determme the storage volume requITements.
From Table 4.1 & 20"/hr, the mmllllum storage volume requITed per acre of:
DIsturbed pervIOus surface = 1,000 cf/ac
ImpervIOUS roadway surface = 3,000 cf/ac
Total dIsturbed pervIOUS area = 0 69 ac + 0 23 ac = 0 92 ac
Totalllllper paved/roof area = 3 69 ac + 1. 05 ac + 1. 29 ac = 6.03 ac
RequITed stor-age volume
0.92 ac (1,000 cf/ac) + 6.03 ac (3,000 cf/ac) = 19,010 cf
Volume of dramrock required to store 19,010 cf
(19,010 cf/O 30) = 63,367 cf of dramrock, VOId ratlO = 3 1
Other optIOns are available for storage and dIscharge of stormwater The
followmg optIOns will be mvestIgated durmg prelnnmary and final deSIgn
phases
. Underground mfiltratIon gallenes
. Open retentIon pond(s)
. Underground mflltratIon vaults
. CombmatIons of dram rock gallenes, vaults, and open pond(s)
ENGINEERING
PLANNING
.
SURVEYING
.
SCA
ENGINEERING
,/
APPENDIX I
SCS SOILS'MAP, SOILS LOGS
.
PLANNING
SURVEYING
.
Date
SOlIs Logged By.
Apphcant:
Yelm Retail Center
SCA#95031
Soils Analysis for Storm water Control Facilities
June, 1995
Robert W Balmelli
S Chamberlain & Associates, Inc.
Armada Retail Company
2001 6th Avenue
SUlte #3202
Seattle, W A 98121
SIte DescrIptIOn.
Yelm Retail Center
SOlI Logs:
Depth
0"-27"
27" -41"
41" -97"
Depth
0".23"
23" -44"
44" -98"
Depth
0"-20"
20" -30"
30" -60"
60" -95"
(c: \data \5031605.log)
(See Dramage Plan for soil log locatIOn)
Test Hole #1
Texture and Color
Black gravely sandy loam
Light brown cobbly sandy loam
Light brown cobbly fine sand
Roots to 57", cobbles to 10" mameter
Mottling
None
None
None
Test Hole #2
Texture and Color
Black gravelly sandy loam
LIght brown cobbly sandy loam
Grayish very cobbly memum sand
Roots to 53", cobbles to 10" mameter
Mottling
None
None
None
Test Hole #3
Texture and Color
Black gravelly sandy loam
LIght brown cobbly sandy loam
Gray cobbly very gravelly coarse sand
LIght brown very cobbly memum sand
Roots to 48", cobbles to 10" diameter
Mottling
None
None
None
None
DOUBLE RING INFILTROMETER TEST RESULTS
seA #95031
INFILTRATION RESULTS
Test Pit #2
Start (Min) Stop (Min) Elapsed Time Total Inches Infiltration Rate
(Min) Drop (In/Hr)
12 32 12 41 9 min 12" 80"/hr
12 43 12 51 8 min 12" 90"/hr
Test Deoth 93"
Weather Conditions
Outside Temperature
Test Performed By
Test Date
Test Holes Dug By
Sunny
780
Brad Shea
6/1/95
Backhoe
(c:\data\5031602.dri)
Pro\ec' Loca"on
SCS MAP NUMBER 20
(110) _ SPAllAWA~ GRA'/ELL~ SAllO~ LOAM
o 10 3% SLOPE
'l'ELM RO AIL C(Nl(R
?- ~ C'~~\
SCS SO\lS MAP