HomeMy WebLinkAboutSWP271761OUR JOB NO. 5240
NOVEMBER 10, 1994
110
EXPIRE 0:7
Prepared By:
BARGHAUSEN CONSULTING ENGINEERS, INC.
18215 72ND AVENUE SOUTH
KENT, WASHINGTON 98032 E rEc7RENTON]
(206) 251-6222
GHqtf�
�fr Z
i r CIVIL ENGINEERING, LAND PLANNING, SURVEYING, ENVIRONMENTAL SERVICES
s� y,
1.0 INTRODUCTION AND GENERAL INFORMATION
The proposed project site is currently developed with an existing building and parking lot. The
proposed project is to add an addition onto the existing building. The site area is approximately
2.4 acres and is zoned Medium Industrial (IM). The site is very flat. There is an existing
detention pond on the north side of the property, which drains to the northeast property corner
through a pipe conveyance system where it enters a control structure. There are no steep slopes
or wetlands on the site. The following is a review of the core and special requirements dictated
in the King County Surface Water Management Manual:
Core Requirements
Core Requirement No. 1: Discharge at the Natural Location. This project proposes to not change
any of the discharge locations. All of the catch basins will remain as they are and the building will
have roof drains which tie into this catch basin system.
Core Requirement No. 2: Off -Site Analysis. This report satisfies Core Requirement No. 2, the
Level I analysis.
Core Requirement No. 3: Runoff Control. It has been determined previously by the City of
Renton that neither additional detention nor biofiltration will be required for this project.
Core Requirement No. 4: Conveyance System. Since this project proposes to add no additional
impervious area, the existing conveyance system should be sufficient to carry the flow from the
proposed development just as it does now with the existing conditions.
Core Requirement No. 5: Erosion and Sedimentation Control Plan. There will be an erosion and
sedimentation control plan prepared for this project.
Core Requirement No. 6: Maintenance and Operations. The existing site was developed in 1987
and, therefore, the existing conveyance and detention systems will not be modified. As a result,
Core Requirement No. 6 does not apply.
Core Requirement No. 7: Bonds and Liability. This requirement will be complied with
Special Requirements
Special Requirement No. 1: Critical Drainage Area. This project does not lie within a critical
drainage area.
Special Requirement No. 2: Compliance with an Existing Master Drainage Plan. A Master
Drainage Plan does not exist for this area.
Special Requirement No. 3: Conditions Requiring a Master Drainage Plan. These conditions are
not exceeded by this project. Therefore, a Master Drainage Plan is not required.
Special Requirement No. 4: Adopted Basin or Community Plans. This project does not lie within
an adopted basin or Community Plan.
Page 1 of 3 5240.001 [JPJ/sdc/krl
Special Requirement No. 5: Special Water Quality Controls. The thresholds of this requirement
are not exceeded.
Special Requirement No. 6: Coalescing Plate Oil/Water Separators. The threshold of this
requirement is not exceeded.
Special Requirement No. 7: Closed Depressions. There are no closed depressions on this site that
we discharge to.
Special Requirement No. 8: Use of Lakes, Wetlands, or Closed Depressions for Peak Rate Runoff
Control. The thresholds of this requirement are not exceeded.
Special Requirement No. 9: Delineation of 100-Year Floodplain. The thresholds of this
requirement are not exceeded.
Special Requirement No. 10: Flood Protection Facilities for Type I and Type II Streams. The
threshold of this requirement is not exceeded.
Special Requirement No. 11: Geotechnical Analysis and Report. The thresholds of this
requirement are not exceeded.
Special Requirement No. 12: Soils Analysis and Report. The thresholds of this requirement have
not been exceeded.
2.0 UPSTREAM DRAINAGE BASIN ANALYSIS
The subject site slopes toward catch basins which drain into a 30-inch storm drain in East
Valley Road. The subject property is also very flat and there is a railroad line running north -south
on the west side of'the property which is lower than our subject property. There is a Puget Power
transformer station on the south side of our subject property that drains into the storm drain in East
Valley Road. The surrounding ground tends to drain in a northerly direction towards SR-405.
3.0 ON -SITE DRAINAGE ANALYSIS
Almost the entire site is considered impervious since it is all building and paved area except for
a strip along the east frontage of East Valley Road. The impervious area is all conveyed by sheet
flow to catch basins, and from there toward the front of the property on East Valley Road. Runoff
passes through a detention system on the north side of the property and through a control structure
on the northeast corner of the property, until it is conveyed into a 30-inch storm drain 15 feet
inside the right-of-way of East Valley Road.
4.0 DOWNSTREAM DRAINAGE SYSTEM DESCRIPTION AND PROBLEM SCREENING
The downstream system along this project is more clearly defined on the attached downstream
drainage map and off -site analysis drainage system table. Please refer to these documents for a
detailed description of the downstream system.
Page 2 of 3 5240.001 [JPJ/sdc/kr]
5.0 RESOURCE REVIEW
The following is a description of each of the resources that was reviewed for the preparation of this
Level I Drainage Study:
A. Basin Reconnaissance Summary Report: The site and downstream basin are located in
the Black River Basin and these documents are included in this report.
B. Critical Drainage Area Maps: The site is not located within a critical drainage area.
C. F000dplain Floodway FEMA Maps: This project is not located within a floodplain of a
stream as determined by the FEMA maps.
D. Other Off -Site Analysis Reports: No other off -site analysis or reports were conducted
for this project.
E. Sensitive Areas Folio: Each of the sensitive areas folios associated with this area was
reviewed. This project does not impact and is not directly impacted by a sensitive area.
6.0 U.S. DEPARTMENT OF AGRICULTURE SOILS SURVEY
The soils survey shows the soils in this area to be Tukwila muck.
7.0 WETLANDS INVENTORY MAP
As discussed earlier, it does not appear that wetlands are located on or near this site.
Page 3 of 3 5240.001 [JPJ/sdc/krl
APPENDIX
EXHIBIT "A": Downstream Basin Map
EXHIBIT "B": Off -Site Analysis Drainage System Table
EXHIBIT "C": Assessor's Map
EXHIBIT "D": Basin Reconnaissance Summary
EXHIBIT "E" : FEMA Floodway Map
EXHIBIT "F" : Sensitive Areas Folio
EXHIBIT "G": Soils Map
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APPENDIX A
ESTIMATED COST: PROPOSED CAPITAL IMPROVEMENT PROJECTS
BLACK RIVER BASIN
Indicates project was identified by Surface Water
Management office prior to reconnaissance.
NOTE: All projects are located on map included
in this report.
Project Collect.
Number Point Project Description
030110 Increase R/D capacity of Panther
Lake by constructing earthen
berms and outlet control.
structure. Trig. 0006, RM 3.40.
0302' 22 Provide regional R/D facility by
constructing earthen dam across
drainage swale. Provide control
structure and overflow spillway on
Trib. 0021 at RM .40 (Springbrook
Creek).
0303' 29 Construct instream R/D facility at
point where Benson Rd. crosses
Garrison Creek. Reinforce
Benson Rd. Construct outlet -control
structure around existing cross
culvert R.M. 1.40.
Problem Addressed
Reduce erosion and flooding
downstream in Panther
Creek.
Prevent erosion to .sensitive
slopes downstream of
proposed site by
reducing peak flows.
Reduce erosion and flooding of
of Garrison Creek by reducing
peak flows.
Estimated Costs
and Comments
$345,000
(Panther Lake is #1
Wetland and will require
agreement to use as R/D
site. Further biological
study also needed at time
of basin planning.)
$208,000
(Project costs should
be shared with City
of Renton.)
$125,000
(Project should be
constructed in conjunction
with proposed Projects
0304 and 0305.)
APA/mlm
APPENDIX B
CAPITAL IMPROVEMENT PROJECT RANKING
BLACK RIVER BASIN
Prior to the Black River Basin field reconnaissance, seven projects had been identified and rated
using the CIP selection criteria developed by the Surface Water Management (SWM) and Natural
Resources and Parks Divisions. Following the reconnaissance, seven projects remain proposed for
this area. They include one new, previously unidentified and unrated project. This displaces one
previously selected project, which was eliminated based on the consensus of the reconnaissance team
because no problem was apparent in the field.
The previous SWM capital improvement project list for the Black River Basin had an estimated cost
of $1,250,000, while the revised list increases to an estimated cost of $1,280,000. This 2.4 percent
increase in estimated capital costs is due mainly to upward revised cost figures for securing or
acquiring easements over wetlands and costs associated with a new project to solve a previously uni-
dentified problem.
The following table summarizes the scores and costs for the CIPs proposed for the Black River
Basin. These. projects were rated .according to previously established SWM Program Citizen
Advisory Committee criteria. The projects ranked below are those for which the first rating
question, ELEMENT 1: "GO/NO GO," could be answered affirmatively. These projects can be
considered now for merging into the "live" CIP list.
RANK
PROJECT NO,
SCORE
COST
1
0302`
125
S 208,000
2
0303 `
110
125.000
3
0309
100
26.000
4
0301 `
95
345,000
5
0305 `
90
116,000
6
0307 `
60
309,000
7
0304 `
55
151.000
TOTAL S1.230.000
` Indicates project was identified by the Surface Water Management Division prior
to reconnaissance.
P:BR.APB. B-1
APPENDIX C
DETAILED FINDINGS AND RECOMMENDATIONS
BLACK RIVER BASIN
" All items listed here are located on final display
maps in the offices of Surface Water Management,
Building and Land Development and Basin Planning.
I rih. & Collect.
Item' River Mile Point CaIego ry Prop. Proi.
Existing
Conditions and Problems
Anticipated
Conditions and Problems
Recommendations
1 0005 3 Ilabitat
RM .30
Fish ladder through pump
Based on the condition of
Develop and implement a comprehensive
plant. Automatic counter
the basin habitat and future
Black River basin plan in agreement
records all .returning
development, these numbers
with all local jurisdictions.
-
anadromous species
(apx. 84 in 1986).
will probably decrease.
Habitat improvement would be one goal
of this plan.
? 0005 12, (, Ilabitat
RM 1.30-
Drainage district has
Condition will continue.
- Contact drainage district about
4.65
removed all stream cover
the feasibility of select pl tnt-
along drainage channel.
ings along the ditch levees.
Water quality looks very
- Develop a plan to address point
poor. Sonic oil and suds on
and nonpoint water quality
surface, also very turbid
problems originating from the
water.
thousands of acres of commercial
and industrial land in the basin.
3 0005 IR Ilabitat
RM `{.30-
Large amounts of sediment
More erosion, sedimentation,
- Increase size and number of R/D
8.70
moving down the stream
and loss of fish habitat.
facilities upstream to reduce
system has filled in
flow volume and rates to non -
all the pools. Kent removes
erosive levels.
1,100 cubic vards of scdi-
ment from Mill Creek at
Canyon Park annually.
1':BR.APC/, C-I
Trih. R Collect. Existing
Item River Mile Point Catc�ory Pro11. Proj. Conditions and Problems
4 0005
RM 10.05
9 0005
RM 10.10-
10.30
19 1labitat
19
10 OOO5A 19
RM 0.2
I1 0006 7
RM .50-
1.a0
P:BR.APC/mlm
Dish blockage due to con-
crcle and asphalt debris
piled in stream.
Ilahitat Native vegetation
removed down to stream edge
and replaced by pasture.
Hydrology 0307
"Tributary contributes to
Mill Creek, which experien-
ces erosion and sediment
transport. Wetland 0303
now provides some R/U and
has much more potential
capacity.
1lahitat Stream flows throuth wet-
land. No visible channel.
Dish transit through this
cattail wetland looks
difficult.
C-3
Anticipated
Conditions and Problems
Condition will continue.
Livestock will erode stream -
bank and defecate in stream
channel. This will result
in erosion, sedimentation,
and water quality problems.
This area will continue to
develop and will contribute
greater runoff to the
downstream conveyance system
The wetland area may be
damaged by development
around the perimeter and this
may decrease the ability of
the surface water to infiltrate.
Runoff will continue to
increase and erosion and
sedimentation will likewise
continue.
Condition will continue.
Recommendations
Encourage Stale Fisheries person-
nel to organize a citizen -action
project to construct a stepped
pool or other solution to allow
fish passage.
- Pence to provide a stream corri-
dor.
- Plant native plants or allow
natural revegetation along
strcambanks.
- Obtain required casements and
construct a regional R/U facility
in wetland area.
- Construct berms along the western
and northern sides of the existing
wetland.
- Increase the storage capacity
of the wetland by excavation.
If anadromous fish were rein-
troduced to Panther Creek,
wetland passage would need to be
assured. A biological assessment
by fisheries and, wetland biolo-
gists would be needed to formulate
a viable solution.
Trib. R Collect.
Item River hlilc Point Category
000E Geology
lZM 2.15
19 0006 10
RM 2.55-
3.00
20 0006 10
RM 3.40
Existing
Prop. Proi. Conditions and Problems
I.,arge landslide (transla-
tional and rotational
failure), with raw slope
remaining; gullying of
slope. Apparently caused
by combination of under-
cutting by stream and
routing of road drainage
over slope from above.
Anticipated
Conditions and Problems
Slide will continue to
contribute to sedimentation
downstream.
Recommendations
Direct surface runoff away from
top of slope to gravel pit
(to west).
Ilahitat Stream in good condition. Possible erosion and loss of - Maintain stream flows at non -
Setbacks and protective habitat if future develop- erosive levels
vegetation needed at points ment increases volume and - Maintain a natural stream corri-
along the stream. Some rate of flow. dor from Panther Lake down into
good pools and spawning and along Panther Creek.
gravel in a few places.
Hydrology 0301
Panther I—ake is a #1-C
wetland that provides a
large amount of natural
storage; the downstream
system is in fair
condition with some
erosion. The contributing
drainage area is not
currently densely devel-
oped.
Future development in this
area will triple the amount
of impervious area. The
available area for regional
R/D facilities may soon be
exausted and the system
will continue unchecked
downstream. Erosive
soils throughout the area
are further threatened
as higher amounts of runoff
will increase the rate at
which the existing stream
erodes.
The sensitive nature of the
wetland would require precise
boundary surveys and control over
the amount of water artificially
retained by the proposed control.
Use Panther Lake as an R/D facili-
ty by constructing earthen berms
on the north and west sides of the
wetland area; construct a control
outlet, enhance and increase the
capacity of the downstream channel
(stabilize with vegetation), and
obtain easements.
P:BR.APC/r C-5
Item
Trib. &
River Mile
Collect.
Point Category
Existing
Prod. I'roj. Conditions and Problems
Anticipated
Conditions and Problems
Recommendations
25
0006C
5 habitat
Rolling Mills Creek exhib-
Littic change due to riprap
None.
its oil sheen on water in
along stream to protect
upper portion of the creek.
sewer line that parallels
Little or no fish habitat
stream.
(or potential) exists.
26
0009
RM
9 Geology
Bank and lower -slope erosion
Flows in tributary will in-
- R/D in upper basin.
.00-
.15
in small tributary channel,
crease; erosion will continue
- Remove fill along stream.
especially behind construe-
causing sedimentation down-
tion equipment lot.
stream and perhaps threaten
stability of building.
27
0009
RM .15-.20
9 habitat
Lots of litter; stream has
Worsening of water quality,
- Reduce the volume and rate of water
extensive downcutting, bank
sedimentation, and erosion.
to non -erosive levels by new R/D.
erosion, and bedload
- Consider restricting future develop -
movement.
ment (down -zone).
- Community action projects could
remove litter.
28
0020
RM .20
12 habitat
Sediment has destroved fish
Possible flooding and sedi-
Remove sedimentation source (.see also
habitat. City of Kent
mentation along S .192nd St:
Trib. 0023, RM.95).
removes sediment each year.
29
0020
.SO-
21. Geology
Bank erosion, landsliding
Problems will continue.
- Control storm flows. Increase R/D
70
70
in canyon due to oulfalls
at end of SE 196th St. and
above RM .40 in 0021; reroute or
from R/D on 200th plus
control flows from vicinity of SG
natural sensitivity
200th (tightline west on 200th).
(landslides). Heavy damage
- Provide energy dissipation at R/D
in Jan. 36 storm. Sedi-
outfall (RM .40).
mentation above old road,
- Restrict development on north side
and in trout farm below
of 0021 (runoff to be tightlined or
Talbot Rd., as well as ero-
routed around ravine).
sion in the ravine.
1':Blt./1PC/r C-7
0
a
LEGEND
SPECIAL FLOOD HAZARD AREAS INUNDATED
BY 100-YEAR FLOOD
ZONE A No base flood elevations determined.
! I ZONE AE Base flood elevations determined.
ZONE AH Flood depths of 1 to 3 feet (usually areas of
ponding); base flood elevations determined.
ZONE AO Flood depths of 1 to 3 feet (usually sheet
flow on sloping terrain); average depths
determined. For areas of alluvial fan flood-
ing, velocities also determined.
ZONE A99 To be protected from 100-year flood by
! Federal flood protection system under
construction; no base elevations determined.
ZONE V Coastal flood with velocity hazard (wave
action); no base flood elevations deter-
mined.
ZONE VE Coastal flood with velocity hazard (wave
action); base flood elevations determined.
FLOODWAY AREAS IN ZONE AE
I
OTHER FLOOD AREAS
ZONE X Areas of 500-year flood; areas of
100-year flood with average depths
of less than 1 foot or with drainage
areas less than 1 square mile; and
areas protected by levees from 100-
i year flood.
OTHER AREAS
ZONE X Areas determined to be outside 500-
year flood plain.
ZONE D Areas in which flood hazards are
undetermined.
Flood Boundary
'— Floodway Boundary
Zone D Boundary
Boundary Dividing Special Flood
Hazard Zones, and Boundary
Dividing Areas of Different
Coastal Base Flood Elevations
Within Special Flood Hazard
Zones.
—513^--- Base Flood Elevation Line; Ele-
vation in Feet*
Cross Section Line
(EL 987) Base Flood Elevation in Feet
Where Uniform Within Zone*
RM7X Elevation Reference Mark
*Referenced to the National Geodetic Vertical Datum of 1929
NOTES
This ;nap is for use in administering the National Flood Insurance Program;
it does not necessarily identify all areas subject to flooding, particularly
from local drainage sources of small size, or all planimetric features outside
Special Flood Hazard Areas.
Areas of special flood hazard (100-year flood) include Zones A. Al.30, AE,
AH, AO, A99, V, V1-30 AND VE.
n areas not in Special Flood Hazard Areas may be protected by flood
structures.
,daries of the floodways were computed at cross sections and interpo.
lated between cross sections. The floodways were based on hydraulic
considerations with regard to requirements of the Federal Emergency
Management Agency.
Floodway widths in some areas may be too narrow to show.to scale.
Floodway widths are provided in the Flood Insurance Study Report.
Coastal base flood elevations apply only landward of the shoreline.
i
Refer to the FLOOD INSURANCE RATE MAP EFFECTIVE date
shown on this map to determine when actuarial rates apply to
structures in the zones where elevations or depths have been estab
lished.
To determine if flood insurance is available, contact an Insurance
agent or call the National Flood Insurance Program at (800)
63"620,
APPROXIMATE SCALE IN FEET
500 O 500
NATIONAL FLOOD INSURANCE PROGRAM
RIM
FLOOD INSURANCE RATE MAP
KING COUNTY,
WASHINGTON AND
INCORPORATED AREAS
PANEL 328 OF 650
PANEL LOCATION
CONTAINS:
COMMUNITY NUMBER PANEL SUFFIX
TUKWILA, CITY OF 530091 0328 D
RENTON, CITY OF 530088 0328 D
UNINCORPORATED AREAS 530071 0328 D
MAP NUMBER
53033CO328 D
EFFECTIVE DATE:
SEPTEMBER 29, 1989
Federal Emergency Management Agency
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GUIDE TO MAPPING UNITS
For a full description of a mapping unit, read both the description of the mapping unit and that of the soil
series to which the mapping unit belongs. See table 6, page 70, for descriptions of woodland groups. Other
information is given in .tables as follows:
Acreage and extent, table 1, page 9.
Engineering uses of the soils, tables 2 and 3,
pages 36 through 55.
Map
symbol Mapping unit
Town and country planning, table 4, page S7.
Recreational uses, table S, page 64.
Estimated yields, table 7, page 79.
Woodland
Described Capability unit group
on
page Symbol Page I Symbol
AgB Alderwood gravelly sandy loam, 0 to 6 percent slopes ----------
AgC Alderwood gravelly sandy loam, 6 to 15 percent slopes---------
AgD Alderwood gravelly sandy loam, 15 to 30 percent slopes--------
AkF Alderwood and Kitsap soils, very steep ------------------------
AmB Arents, Alderwood material, 0 to 6 percent slopes 1/----------
AmC Arents, Alderwood material, 6 to 15 percent slopes 1/---------
An Arents, Everett material 1/----------------------------------
BeC Beausite gravelly sandy loam, 6 to 1S percent slopes ----------
BeD Beausite gravelly sandy loam, 15 to 30 percent slopes---------
BeF Beausite gravelly sandy loam, 40 to 75 percent slopes ---------
Bh Bellingham silt loam ------------------------------------------
Br Briscot silt loam ---------------------------------------------
Bu Buckley silt loam ---------------------------------------------
Cb Coastal beaches -----------------------------------------------
Ea Earlmont silt loam --------------------------------------------
Ed Edgewick fine sandy loam --------------------------------------
EvB Everett gravelly sandy loam, 0 to 5 percent slopes ------------
EvC Everett gravelly sandy loam, 5 to 15 percent slopes -----------
EvD Everett gravelly sandy loam, 15 to 30 percent slopes ----------
EwC Everett-Alderwood gravelly sandy loams, 6 to 15 percent
slopes------------------------------------------------------
InA Indianola loamy fine sand, 0 to 4 percent slopes --------------
InC Indianola loamy fine sand, 4 to 15 percent slopes -------------
InD Indianola loamy fine sand, 15 to 30 percent slopes ------------
KpB Kitsap silt loam, 2 to 8 percent slopes -----------------------
KpC Kitsap silt loam, 8 to 1S percent slopes ----------------------
KpD Kitsap silt loam, 15 to 30 percent slopes ---------------------
KsC Klaus gravelly loamy sand, 6 to 15 percent slopes -------------
Ma Mixed alluvial land -------------------------------------------
NeC Neilton very gravelly loamy sand, 2 to 15 percent slopes------
NgNewberg silt loam ---------------------------------------------
Nk Nooksack silt loam --------------------------------------------
No Norma sandy loam ----------------------------------------------
Or Orcas peat ----------------------------------------------------
Os Oridia silt loam ----------------------------------------------
OvC Ovall gravelly loam, 0 to 15 percent slopes -------------------
OvD Ovall gravelly loam, 15 to 25 percent slopes ------------------
OvF Ovall gravelly loam, 40 to 75 percent slopes ------------------
PC Pilchuck loamy fine sand ----- 7--------------------------------
Pk Pilchuck fine sandy loam --------------------------------------
Pu Puget silty clay loam -----------------------------------------
Py Puyallup fine sandy loam --------------------------------------
RaC Ragnar fine sandy loath, 6 to 15 percent slopes ----------------
RaD Ragnar fine sandy loam, 15 to 25 percent slopes ---------------
RdC Ragnar-Indianola association, sloping: I/ ----------------------
Ragnar soil----------------------- ----------------------
Indianola soil-------------------------------------------
RdE Ragnar-Indianola association, moderately steep: 1/ ------------
Ragnar soil -------------------------------- -------------
Indianola soil-------------------------------------------
108
10
10
10
10
11
11
12
12
12
13
13
14
14
15
15
16
16
16
17
16
17
17
18
18
18
18
19
19
20
20
21
21
22
23
23
23
23
24
24
25
26
26
26
IVe-2
IVe-2
VIe-2
VIIe-1
IVe-2
IVe-2
IVs-1
IVe-2
VIe-2
VIIe-1
IIIw-2
IIw-2
IIIw-2
VIIIw-1
IIw-2
IIIw-1
IVs-1
VIs-1
Vle-1
VIs-1
IVs-2
IVs-2
VIe-1
IIIe-1
IVe-1
VIe-2
VIs-1
VIw-2
VIs-1
IIw-1
IIw-1
IIIw-3
VIIIw-1
IIw-2
IVe-2
VIe-2
VIIe-1
VIw-1
IVw-1
IIIw-2
IIw-1
IVe-3
VIe-2
IVe-3
IVs-2
VIe-2
VIe-1
76
76
78
78
76
76
77
76
78
78
76
75
76
78
75
75
77
78
77
78
77
77
76
75
76
78
78
78
78
74
74
76
78
75
76
78
78
78
76
76
74
77
78
77
77
78
77
3d2
3dl
3dl
2dl
3d2
3d2
3f3
3d2
3dl
3dl
3w 2
3w 1
4w 1
3w 2
2ol
3f3
3f3
3f2
3f3
4s3
4s3
4s2
2d2
Zd2
2dl
3f1
2ol
3f3
2ol
2o1
3w 2
3w 1
3dl
3dl
3dl
2sl
2sl
3w 2
2o1
4s1
4sl
4s1
4s3
4s 1
4s2
U. S. GOVERNMENT PRINTING OFFICE : 1973 0 - 466-266
GUIDE TO MAPPING UNITS --Continued
Map
symbol
Mapping unit
Described
on
page
Capability unit
Woodland
group
Symbol Page
Symbol
Re
Renton silt loam--------------------------------------------
26
IIIw-1
75
3wl
Rh
Riverwash---------------------------------------------------
27
VIIIw-1
78
---
Sa
Salal silt loam---------------------------------------------
27
IIw-1
74
2ol
Sh
Sammamish silt loam-----------------------------------------
27
IIw-2
75
3wl
Sk
Seattle muck------------------------------------------------
28
IIw-3
7S
---
Sm
Shalcar muck------------------------------------------------
29
IIw-3
7S
---
Sn
Si silt loam------------------------------------------------
29
IIw-1
74
2ol
So
Snohomish silt loam-----------------------------------------
30
IIw-2
75
3w2
Sr
Snohomish silt loam, thick surface variant------------------
31
IIw-2
75
3w2
Su
Sultan silt loam--------------------------------------------
31
IIw-1
74
3w1
Tu
Tukwila muck------------------------------------------------
32 1
IIw-3
75
---
UrUrban
land--------------------------------------------------
33
--------
--
---
Wo
Woodinville silt loam---------------------------------------
33
IIw-2
75
3w2
l/
The composition of these units is more variable than that of the others in the Area, but it has been
controlled well enough to interpret for the expected use of the soils.