HomeMy WebLinkAboutMisc 1 of 2i PLAT & SITE CIVIL DESIGN, LLC
September 22, 2008
Lanny Henoch
King County DDES, Land Use Services Div.
900 Oakesdale Ave SW
Renton, WA 98057-5212
RE: Lenora Short Plat, KC File No. L07SO079
6-lot short plat
Pareel # 619660 0100
Dear Lanny:
In response to Fereshteh's February 13 letter:
KCRS
1. A variance to Road Standards has been received (attached).
2. The right-of-way line and curb radii have been added.
2005 KC SWDM
1. The conceptual drainage plan has been prepared, stamped and signed by me, a
registered professional engineer.
2. We disagree with the assessment that the stormwater from this site flows "through" a
sphagnum bog. The arguments presented are attached.
IFC
It is acknowledged that sprinklers will be required if the road is not widened. We have
opted to leave the road as -is, and acknowledge that sprinklers will be required. A note
has been added to that effect.
Wetland
An evaluation has been performed by a certified wetland biologist, attached. None was
found.
37702 280PI SE
Enumclaw, WA 98022
Tel (253) 334-6990 Fax (206)242-4209 email dennis@platandsitecivildesign.com
Recreation Tract
The recreation tract has been relocated in accordance with the February 13 letter.
KCC 19A, Site Plan
Two monuments have been depicted.
A note has been added that the contours are based on an actual field survey.
Attached are:
■ Six copies of revised site plan ("Preliminary Plat")
■ Six copies of revised conceptual road and drainage plan. It will be noted that the plan
does not include a sand filter, which would be required by the sphagnum bog
treatment menu, as we disagree with the assessment that the project is subject to that
requirement.
■ Four copies of the wetland/stream report.
■ Four copies of the road variance that was granted.
Not attached is a revised drainage report. As we disagree with the assessment that the
project is subject to the sphagnum bog treatment requirements, there were no changes to
the report.
GN LLC
Lanny,
I want to make sure the City of Renton gives due consideration to our case regarding the
bog, and does not simply rubber-stamp King County's recommendation regarding the
disposition of the preliminary plat.
I would imagine they would give consideration in any case, but do you have any
suggestions as to how we can be sure? For example, might you draw their attention to
the dispute and let them know we have a substantive issue?
What I'm concerned with is that, I don't know whether or not they would have a
tendency to prejudice to the position of a fellow governing agency, but before they make
a negative decision, I would like to opportunity to go in to the City to present our case.
So I want to make sure there is a channel for that.
Dennis
FIE L��E9dWR D
SEP 19 2008
K.C. D.D.E.S.
Altmann Oliver Associates, LLc AOA
I'i) I'n l,nin. ti„ii, 11 1'3tir, 1 11!I 1
September 3, 2008
Dennis Alfredson
Plat & Site Civil Design LLC
37702 280t' Pl. SE
Enumclaw, VITA 98022
SUBJECT: Lenora Short Plat, Fling County File No. L07SO079
Dear Dennis:
1'_11\II'(S wlC'lll;kI
I�I:11311lI1 ti t�'
It I �('�kl �t_�
1'S ' l l l l t' (' l k k 1' ('
AOA-3753
a E(9'T�W[E [D
SEP 2 g 2008
K.G. D.D.E.S.
As you know, King County is requiring that the subject project utilize the sphagnum
bog protection standards of the 2005 KCSWDM since stormwater from the project
will eventually enter Soos Creek 2, a large downstream wetland with a mapped bog
component. As outlined in a July 23, 2008 e-mail from Kate Rhoads, the bog
standards would not apply if "a qualified wetland biologist identifies that either 1)
stream flows through the wetland are in a confined channel and would not come into
contact with the bog portion of the wetland or 2) there is no bog, and DDES confirms
their findings".
On August 29, 2008 1 conducted a reconnaissance of the Soos Creek 2 wetland
located downstream of the subject property to review the requirements outlined by
Kate Rhoads. During the reconnaissance, the wetland was traversed from west to
east through the mapped bog portion of the wetland. The bog component was
positively identified and the mapped boundaries of the bog appeared to reasonably
match the field conditions.
The eastern edge of the bog was fairly well defined and there was a clear break
between the bog vegetation (primarily Labrador tea and bracken fern) and the mostly
willow swamp located further to the east. After leaving the bog component, the
elevation dropped what appeared to be several feet before shallow ponding was
encountered within the willow swamp. Based on this field observation, the bog
component is perched above the main body of the wetland.
The main body of the wetland was then walked to the power line corridor located in
the northeastern portion of the wetand. Although shallow ponding was observed
Dennis Alfredson
September 3, 2008
Page 2
throughout this portion of the wetland, no confined channel or noticeably flowing
water was encountered.
Based on the reconnaissance, it appears that runoff entering the wetland disperses
throughout the willow -dominated plant community_ Due to the perched condition of
the bog component it appears likely that any potential surface overflow into the bog
would only occur during high -flow precipitation events. Since it is my understanding
that low-frequency/high volume flows are not treated as part of the bog protection
standards, it appears that application of the bog protection standards for the subject
project would provide little or no benefit to the bog component_
If you have any questions regarding the reconnaissance, please give me a call.
Sincerely,
ALTMANN OLIVER ASSOCIATES, LLC
?_ aRkL�
John Altmann
Ecologist
�,. PLAT & SITE CIVIL DESIGN, LLC
September 16, 2008
Steve Foley
King County Water and Land Resources Division
Steve. Foley@kingcounty.gov
RE: Lenora Short Plat
6-lot short plat
Parcel # 619660 0100
Dear Steve:
IF @7 EWE P
SEP 2 9 2008
K.C. D.D.E.S.
I understand that, as it stands currently, King County will recommend to the City of
Renton that the short plat application be denied, based on the lack of a sphagnum bog
water treatment facility. I am told that if you can be persuaded of the lack of need for
such a facility, the County would recommend approval. Consequently, I would ask you
to consider:
■ The very definition found in the Manual says, " ... bogs are isolated from surface
water, being supplied almost solely by rainwater. " It is clearly inconsistent to
suppose that the bog is being regularly overwhelmed by stormwater runoff from the
upstream drainage basin, especially of this size (approximately 360 acres).
■ An internet source of definition is more precise, "Bog is the common name for peat
systems having the sphagnum association described, but this term applies strictly only
to systems that receive water income from precipitation exclusively. "
■ Another internet source, "wetlands with a high cover of sphagnum, such as bogs, are
by definition, elevated above the normal high water mark. "
■ Sphagnum bogs are characterized by acidic, anoxic (no oxygen), low nutrient waters.
Quoting a King County source found on the internet, "In addition to a distinctive
plant community, the water chemistry of sphagnum bogs is also unique. It is
characterized by acidic waters (pH3 to 5.5), low nutrient content, low alkalinity, and
a buffering system composed predominantly of organic acids. " Sphagnum moss is
specially adapted for life in such waters. 5tormwater runoff does not carry any of
these characteristics.
■ The water quality design flow is either 60% of the 2-year peak flow rate (in the case
of facilities preceding detention) or the full 2-year peak flow rate (facilities following
detention). Restated, every single rainfall event, every drizzle, every shower, every
37702 280 PI 5E
Enumdaw, WA 98022
Tel (253) 334-6990 Fax (206)242-4209 email dennis@platandsitecivildesign.com
It seems that, 10 or so years ago, a King County biologist eyed the bog, eyed the nearby
streamflow, and made a judgment that the bog could be inundated by the stream.
Whether or not it could be inundated at all is debatable, but I would contend that it
certainly cannot be inundated regularly (i.e., more often than 60% of the 2-year) by virtue
of the evidence and definitions found above. This made judgment, on which this whole
issue rests, should now be discarded in light of the arguments above.
My hope is that you will find these points reasonable and compelling, and save us from
the task of making our case to the City of Renton.
DESIGN LLC
Cc: Curt Crawford
attachments
isog tsogs real �,pnagnum Moss gent lauel Ireland Plants England
Page 1 of 1
ECONO C ADou Lis Contact Us terms Privacy
experf.com Search ----------_._—_ BO
Index: >ABGt3EFGHIJKLMNoPQRSTUVWXYZ Business Industries Finance Tax
Home;, Bog
First Prev i 1 21 Next Last
A bog rs a w tan,' r„^o `,hat 2 -_ a at^s ,.ea, m o r 'n rn>^ o .Isa.gF r. rnr -, ,f, rll; ;"dur ar-t a th,..rh 0
wouid be propel to call thes sphagnum bogs if the peat is comprised mostly of acidophilic moss (pea Sphagnum spp-)- Lichens are a principal
component of peat in the f north. It is typical of bogs that they have no significant inflows or outflows. Moisture is ovided by precipitation and for this
reason bog waters are acidi -
>!?oga ore :vfid' lF' d',st ih;itp 1 in coin, temp af^ .IimatF mayfly in the ne t^err ^ s^bete 'Irree : Thm wcrld'�-' Inrge=t wrPLe ncls n,re'he hoq,s of the
Western Sioerian Lowiands in Russia which cover more than 600,000 square kilometres. Sphagnum bogs were widespread in northern Europe. ireland was
more than 15 per cent bog: Achill Island off ireiand is 67 per cent bog. There are extensive bogs in Canada {called muskegs}, Scotiand and Finland. There
are also bogs in the Falkland Islands
There exist other terms for what are bogs or peat wetlands similar to bogs The term moor refers to a fiat, boggy area with patches of heath and peat moss
(that is. a bog) An example of this wetland type is the vast expanse of moorland in south-west Fngfand, Dartmoor
1 Bog habitats
F'<7qS arc chalienning envim^mints for plant life bccausr they are icw in nutrients and v^n acidic_ Car^Ivo_r_ci.is plants ;.ave adapted t':: those eanditio^r. b'.f
using insects as a nutrient source The nigh acidity of bogs and the absorption of water by sphagnum moss reduce the amount of water available for plants.
Some bog plants. such as Leatherleaf have waxy leaves to help retain moisture. Bogs also offer a unique environment for animals. For instance. English
bops give a home to the boahopper beetle and a yellow fly called the hairy canary .
Some bogs have preserved ancient oak logs useful in dendrochronoiogy and they have yielded extremely well-preserved bog bodies with organs skin and
hair intact. such as Tollund Man and Lindow man. buried there thousands of years ago after apparent Celtic human sacrifice
PoliticsBusiness Finance
i . ,
Topics: Bog Bogs Peat Sphagnum Moss Cent Fuel Ireland Plants England...
Bogic Eoggar. Boggle
Bogosort Bog body Bogart, Georgia
Boque, Kansas Bogalusa, Louisiana Bogus Brook Township, Minnesota
Bogard, Missouri Bogota. New Jersey Bague. North Carolina
Boger City, North Carolina Boggs Township Armstrong County, Pennsylvania Boggs Township, Centre County, Pennsylvania
0 a, Bookmark %' Set As Hornepage o Print f Top
Fri Sep 12 03:12:22 2008 LconomicExpert-com
This x=Yicly is from Willtivdia iiecns�d iuider the G!t Frey LiCCIFSB it ri rCi rnaiuriul prom Ihe. Wi3 tpcarr amcle 1i",_
'f11e ll4 or all aurhnrra is avadeaile under ih3, link
'17rc ❑lijCle c.uz hr ti:diticd nerc
http://www.economicexpert.com/a/Bog.htm 9/12/2008
Elh Edt V� Ft.+prtpes TpoE; Fldp
-;a µlr C; - sp�m bog " 6b , Ck -� 04 ) F i? Bookmaks- "'� O-Mk - > lluU"* - � Sand to- LIT L.J smrmwate- FAfix Q past EltSetrirx�s-
"&AVG • Seach Ger ma e
{; ',LQStDrMWMg• Tams antl Ahhr&AMh _ Copy I'd Sot a '-y' Home - ❑ Porte : F Print -Page . To*, n
The system of pipes and pump stations that collect and transport wastewater from homes and businesses to a
wastewater treatment plain.
Shoreline development
The proposed projects reguOrlad by the Shoreline Managemery Act. Usually this includes the construction over
water or within a shoreime zone (generally 200 feet landward of the water) of stiuctutes such as buildings.
piers. bulkheads. and hreakwateM m6uding emi-onmentel alterations such as dredging and figrng. or any
protect which Interferes with public nayrgahonal rights on the surface waters.
Sphagnum bog VMdonds
Unique wetlands having a predominance or sphagnum moss creating a substrate upon which a disbnel"
community of plants is established- Some of these include ledum gmenlandicrun (Labrador tea). Kalmia
oceidentalis (bog laurel). Drosma rotundifaim (sundew). and Vaccmum mycoccos (crenberry). Sunned
evergreen tress are also sometimes present. In additfon to a drytincove plant community, the water chemestry
of sphagnum wetlands is also unique. 11 fs crreraclerfzed by acidic waters (pR 3 to 5.5), low nutrient content,
low alkalinity. and a buflering system composed prowni morally of organic acids. In ere Puget Sound area.
mature sphagnum bog wellends are typically very aid, often dating back thousands of years.
Storrmnatar
5lermwater Is the water that runs Off surfaces such as rooftops. paved Streets. highways. and parking kills. It
can also come from hard grassy surfaces like lawns, play fields, and from graveled roads and parking lots
Stormwder Feciftgf
Facilities dim comml the discharge of stormwefer and that fernvae pollutants make up the bulk of the structural
solutions applied to surface water problems in Nng County. Stormwater facilities included storage facilities
(ponds, vaults. underground Tanks. and inbtlration systems); water quahry faodrhe . (welponds, bofillretion
swalesconstrmted wetlands. sand flus b . and diVwatar Separators). and conveyance systems (ditch%, pipes,
and catchbuesins)-
These systems are most often built in conjunction with crew development, but mckide regional facilities
designed and constructed by the Department of Natural Resources.
__... -..----------._..__..,__�...._.__....._._.--- ---_.- _. ........ _.__....-.
Srternet .IOU%
.• r
V rlr U�e5 Olnc 'x b'L. r - wr-ioso ma . Jac,, - . .r0. _ f ! / m)rr: Pr rotF T_'.;Jwr LRrdergrc. /_: , • t ... i- �AutoCpn UW€ 3„, +nssU] 1k6.$ii78
Ribes species (currants)
Sphagnum species (sphagnum mosses)
c'
Rhodode ron groen an r tea)
Vaccinium oxycoccos (bog cranberry)
Kalmia microphylla, ssp. occidentalis (bog laurel)
plants that should Hedera helix (English ivy)
not h# introduced to
g, created, or Phalaris arundinacea (reed canarygrass)
constructed Puget Sound
Basin freshwater Lythrum sal icaria (purple loosestrife)
wetlands
Iris pseudacorus (yellow iris)
Ilex aquifolia (holly)
Impatiens glandulifera (policeman's helmet)
Lotus corniculatus (birdsfoot trefoil)
Lysimachia thyrsiflora (tufted loosestrife)
Myriophyllum species (water milfail, parrot's feather)
Polygonum cuspidatum (Japanese lmotweed)
Polygonum sachalinense (giant knotweed)
Rubus discolor (Himalayan blackberry)
Tanacetum vulgare (common tansy)
Native plants that should
Potentilla palustris (Pacific silverweed)
not be introduced to
existing, created, or
Splarum dulcimara (bittersweet nightshade)
constructed Puget Sound
Basin freshwater
Juncus effusus (Soft rush)
wetlands
Gonium maculatum (poison hemlock)
Ranunculus repens (creeping buttercup)
February 2005 Volume l — Minimum Technical Requirements D-29
Pretreatment The removal of material such as solids, grit, grease, and scum from
flows prior to physical, biological, or physical treatment processes to
improve treatabiiity. Pretreatment may include screening, grit
removal, settling, oil/water separation, or application of a Basic
Treatment BMP prior to infiltration.
Priority peat systems Unique, irreplaceable fens that can exhibit water pH in a wide range
from highly acidic to alkaline, including fens typified by Sphagnum
species, Ledum aroenlandicum (Labrador tea), Drosera rotundifolia
(sundew), and Vaccinium oxycoccos (bog cranberry); marl fens;
estuarine peat deposits; and other moss peat systems with relatively
diverse bed flora and fauna! Bog is the common name for
peat having the Sphagnum association described, but this term
applies strictly onlv to systems that receive water income from
precipitatio exclusively.}
Professional civil A person registered with the state of Washington as a professional
engineer engineer in civil engineering.
Project Any proposed action to alter or develop a site. The proposed action of
a permit application or an approval, which requires drainage review.
Project site That portion of a property, properties, or right of way subject to land
disturbing activities, new impervious surfaces, or replaced impervious
surfaces.
Properly Functioning Equivalent to engineered soil/landscape system. This can also be a
Soil System (PFSS) natural system that has not been disturbed or modified.
Puget Sound basin Puget Sound south of Admiralty Inlet (including Hood Canal and
Saratoga Passage); the waters north to the Canadian border, including
portions of the Strait of Georgia; the Strait of Juan de Fuca south of the
Canadian border; and all the lands draining into these waters as
mapped in Water Resources Inventory Areas numbers 1 through 19,
set forth in WAC 173-500-040.
R/ll See Retention/detention facility.
Rare, threatened, or Plant or animal species that are regional relatively uncommon, are
endangered species nearing endangered status, or whose existence is in immediate
jeopardy and is usually restricted to highly specific habitats.
Threatened and endangered species are officially listed by federal and
state authorities, whereas rare species are unofficial species of
concern that fit the above definitions.
Rational method A means of computing storm drainage flow rates (Q) by use of the
formula Q = CIA, where C is a coefficient describing the physical
drainage area, I is the rainfall intensity and A is the area. This method
is no longer used in the technical manual.
February 2005 Volume I — Minimum Technical Requirements Glossary-37
Estimating the Normal Nigh Water Mark Using the Northwestern Ontario Wetiand Ecosystem Classification
Table 1 (page 4) describes classes of wetlands and suggests their suitabil-
ity for buffering aquatic habitats from the effects of forest management
activities. It also relates those wetland classes to the ecological factors impor-
tant for considering their value for buffering aquatic habitats. Other important
considerations include:
• repetitive flooding influences the wetland vegetation, making wetland
plant communities a good indicator of normal high water activity;
• water bodies bordered by open wetlands do not receive the shading
benefits of trees further inshore than 20 to 30 metres;
• wetlands with a high cover o sp agnum, such as bogs, are by definition,
elevated above the normal high water mark;
• m complexes contain muc pan o ass and accumulated
organic material (peat) that provide both a buffering and filtration role;
and,
• many wetland types that have value for buffering waterbodies are readily
interpreted from aerial photography.
Determining the high water mark through the use of wetland ecosystem
indicators is an objective way of assessing seasonally fluctuating hydrologi-
cal conditions. Wetland plant communities and ecosystems often occur as
part of a heterogeneous wetland complex including many community types.
However, these complexes often occur in a predictable and ordered sequence
from open water to "drier" wetland types. Determining the point at which the
wetland complex provides adequate buffering potential from timber manage-
ment activities will require training in the use of the wetland ecosystem
classification, and skills in wetland plant identification.
Discussion
Riparian timber reserves fulfil many roles. They provide shade and assist in
regulating water temperature. They also contribute to the deposition of litter,
insects, pollen and other organic material which become part of the food
chain. Overland sediment and nutrient transport are primarily accomplished
through the presence of undisturbed, permeable forest soils, a function that
should also be provided by undisturbed shrub or heath ground cover, particu-
larly since these are usually on very low slopes.
Riparian reserves have more value than just protecting fish habitat and
water quality (Pike and Racey 1989). Treed reserves are often rationalized on
the basis of the fish habitat guidelines but are intended to provide habitat for
other species and protection of aesthetic values, especially around tourism
lakes. Wetlands are also important riparian habitats for both fish and terres-
trial wildlife. Forest management planning must address wildlife habitat as
part of a broad ecosystem -based approach to management.
NWsr TN-039
wlldlite & rientage service - C:oastal Plain tsogs in Marylancl
rage 1. of
k
' ilvtnrylarir� De;jarlrnent of Nolurai Resources
all
kU & H
Coastal Plain Bogs in Maryland
When most people think of bogs, they think of huge quaking mats of
sphagnum moss surrounded by evergreens in the far North ... or of the
vast wet moors of northern Europe. Few Marylanders realize that we
have a number of small bogs right here on our Coastal Plain. These
unusual wetlands are important and threatened in our state_
Bogs are open, acidic, nutrient -poor wetlands with sphagnum moss,
heath shrubs, wildflowers, and often with insect -eating plants. Bogs form
when a mat of vegetation, especially sphagnum moss and sedges,
develops on the edge of a pond, lake, wetlands, or slow -moving stream,
and eventually grows over the surface of the water. As time passes, the
dead, decaying plants form a dense, fibrous layer known as "peat." Living
moss, sedges, and shrubs take root in the developing peat, holding it
together and becoming part of it when they die.
op, ey become highly stressful environments for malist
plants. The still or slow -moving water is very acidic and contains a mit
supply of nutrients, such as nitrogen, that are needed for plant growth.
The partly decayed vegetation adds organic acids to the bog, slowing
further decay and limiting the release of nutrients. If the peat layer is
thick, it keeps water and nutrients from circulating freely. Most typical
wetland plants cannot survive in the nutrient -poor, acidic 'environment, Dut
a w p ant species, such as Gran ernes, sun- eew , aand sphagnum moss,
afe-especially adapted for life in the bog. 1
Most of Maryland's original Coastal Plain bogs are believed to have
formed when fires removed woody vegetation and humus from certain
swamps during periods of drought. When the water table returned to
normal, the lack of woody vegetation allowed bog species to invade the
wetland edges, where wet, sandy soils provided the appropriate
conditions. Coastal Plain bogs may also have developed in some
"oxbow" lakes (the section of a meandering stream cut off when the
stream changed course) and in old beaver ponds.
More than three centuries of human activity, including fire suppression,
forest clearing, and the draining and filling of wetlands for agriculture and
development, have radically altered the landscape of Maryland's Coastal
Plain. These changes have destroyed many of Maryland's original
Coastal Plain bogs and have confined most new bog formation to a few
artificial sites that mimic the natural soil and water conditions required for
bog formation. Maryland's few remaining Coastal Plain bogs harbor many
species that are rare or endangered in the state, and these important
habitats deserve our protection.
A Walk Through a Coastal Plain Bog
http://www.dnr.state.md.us/wildlife/bogs.html 9/ 12/2008
5191
Hatch's Click Beetle
Eanus hatchi
Range:
Lowland sphagnum bogs of northwest Washington (Johnson 1979).
Washington Distribution:
Historically known from Snohomish County and King County. Currently confirmed
only in King County(Johnson 1984).
Habitat Requirements:
Hatch's click beetles inhabit eutrophic sphagnum bogs in or near lakes below
1,000m (3280'). They have been collected in very low, floating mats of vegetation
in pure sphagnum bogs (Lane 1938). Larvae have been found dear the bog
margins, above the water line (Lane 1971). Adults probably feed on honey dew,
pollen, nectar, and small soft insects. Larvae probably are plant and small insect
predators (Johnson, pens. comm.).
Limiting Factors:
Unknown.
Managements Recommendations:
Prevent all activities that might alter the condition of sphagnum bogs where
Hatch's click beetles occur. These include peat mining, filling, draining,
construction within the bogs, and other activities. Changing the natural water level
or flow rate within the bogs should also be prevented.
Insecticides, and herbicides that could damage wetland vegetation, should not be
applied in sphagnum bogs. Persons wanting to apply chemicals to adjoining lands
should not a nd drift will carry the chemicals
into the bfig. Stormwater runoff should not be diverted into sphagnum bogs.
Decisions ab emica sis
and should consider type of chemical used, season, topography and other
relevant features.
Exotic fish could potentially prey upon beetle larvae and should not be introduced
into wetlands occupied by Hatch's click beetles.
References:
Comstock, J.H. 1960. An introduction to entomology. Comstock Publishing Ass.,
New York, NY.
Lane, M.C. 1971. In: M.H. Hatch, The beetles of the Pacific Northwest. Univ. of
Washington Publications in Biology 16:28-29.
low high
stable stable or fluctuating
Bottom line:
Sphagnum bogs are isolated
from the influences of
groundwater &/or surface
water runoff in some way
.topography (small
watershed, flat area)
.impermeable layers
o blue clay
o decomposed peat itself
. raised character of
hummocks or plateau
. moat or lagg
L
VE
PLAT & SITE CIVIL D€SIGNy LLC
December 24, 2007
Fereshteh Dehkordi :. .
King County DDES
RE: Application for Preliminary Short Plat
Lenora Apartments, LLC
King County File #A07PM 1976
Parcel Number 619660 0100
17800 116' Ave SE
Dear Fereshteh,
In response to your letter, attached are four copies of an expanded SECTION III:
OFFSITE ANALYSIS. 1 believe you will find it more satisfactory and consistent with
the directions of the SWDM.
Also attached are copies of the Downstream Analysis that was done for the nearby,
recently recorded, plat of Woodberry, aka Petro Vista. PetroVista is roughly 1,000 feet
downstream of Lenora Short Plat.
Respeeduily,
PLAT So SITE IVIL DESIGN LLC
I
Dennis 8 ,. edson, P.E.
37702 28e PI SE
Enumclaw, WA 98022
Tel (253) 334-6990 Fax (206)242-4209 email den nis@platandsitecivildesign. oom
Lenora Short Plat
SECTION III; OFF SITE ANALYSIS
SUMMARY NOTE: The nearby 18-lot plat of Woodberry (originally known as Petro Vista, on the
cornet of 118'' Ave SE & Petrovitsky), which was recorded in March of this year, drains to this
same downstream course, and has a considerably larger potential impact than this subject
short plat. The owners of the subject short iplat, Lenora Apartments, LLC offer to examine and
potentially proportionally share in any mitigation costs that were defined and have been agreed
upon by the developers of Woodbegy as a result of specific problems that are identified in its
downstream analysis, if any,
TASK 1: DEFINE AND MAP STUDY AREA
►gy s
I WSW
L1 �aeL4 r.. t 's6 is
4
l caod address lahaVs
I
S L c e- EF r( j i y69
i
all l� 9€iTdi {i ���rr• i 'qh � �. �
Al o'y
� 1 � � � i � _' y$'-t7FE�1�"JAff C,9NIPLhII�T •,( �J
m zm. ycw r 5�7—
downstream path showing contours
Lxb—{ —V, Area
L—
PotentialAn abw
N
5—,%
Ll -� 100 Ye; Hoods_
,J fiOo-Lhvals
Ll C ire ragvaton
raia.d A—
Laken " Lmge
R'vers
sn $LRams
-. K" C—ty Iireiruge
!lase
"Canty '.Hater
Resanr lmwbl y
Ar—
r- MMPsi
le sleek
71 dP oDd[
In IwmWated Am*
ih :r paatedArea
labels
zM1 w emu
[J MoiwtW Peaks
J 9.d d Reief
C—t. a (loaf, Ill)
12124l2007L:nat & Site Civil AesignW-enora AptsMl4 Lenora 07-12-05.doc
Page 12 of 38
Lenora Short Plcal
ar 3.716.4 ft g.gr—, L 973.9 ft Area 24.506 acres
t e r ri s t -a'r.t-- ar• �,. •�'TT �.�-, � - y - �«�. � �'�m".:'u'� - `.-'�*l�iic"iPF n.�r: .* ��.r,- *F"r."'
12 >+-+t17 3ti^.r"'
"_.�,_ `�"• t� � ���f i ,t`2 T �' -� r_ s � _�` r'f � .� ; air.— M,t�
111 Y't -
Tr. 4 J
R4 _ —` r s tit ry a i V
:
1.
�x
r:
r
R-8 s ,
+, ! R-6
R-®'
downstream path showing imagery
12124/2007L.iPlat & Site Civil DesignlLenora AptsInR Lenora 07-12-05.doc
Page 13 of 38
Lenora Short Plat
0
17
H Si 3e 1 tr9+yRR? ,�s� ♦� ,. a y4 }} ,y� - ,.
YJ
� � ti 1`{ l�� "�� ♦ • � . is "fit � �F,.� ." � `�`c �• e :ar,,,�
� r
;rj s R'o xt �I trr.3yj + Y�q ii l l 1 r�ri✓1 k
�, dti•--�^'C',y il-^',.5.,' 1 iH So M Nrk �ntl:fn if
1
-
1'
Rat
� I- 3 .� - f '�F- yir, •d-0r 4.rrt. `1R,..,,
' R4
`R-6,
-
` ✓� R•6J
R-6
vp fi �•<i y le Naw 7.: = to R-6 R-6 �.
,Y, r
„ c ccHtl R-6
downstream for one mile.
TASK 2: REVIEW ALL AVAILABLE INFORMATION
• Adopted basin plan from DDES: A basin plan has been adopted for the Soos Creek
Basin, and is included in the Level 1 Downstream Analysis that was prepared for Petro
Vista (separate document).
• Drainage studies from DNRP Water and Land Resources Division: Numerous drainage
studies have been prepared since 1972_ Several summaries were examined on the
intemet- Refer to DNRP to ascertain whether there were any findings relevant to this
short plat.
• Basin Reconnaissance Summary Reports from DDES: KCR 1735 is available but was
not examined.
• Critical Drainage Area Maps: This parcel is not within a Critical Drainage Area.
• FEMA maps: The Districts Report indicates that a 100-year floodplain has not been
mapped on this parcel. Further, the MAP layer "floodplains" does not indicate
floodplains exist on this parcel. Floodplains do exist downstream in the Soos Creek
basin.
• Other offsite analysis reports: An offsite analysis for Petro Vista was prepared, and is
attached as a separate document..
• Sensitive Areas Folio: The Sensitive Areas Folio shows no sensitive areas on this site.
1212412007LAPiat & Site 00 DesignlLenora Apts1riR Lenora 07-12-05.doc
Page 14 of 38
Lenora Short Plat
• Drainage Complaints to DNRP: According to the iMAP layer drainage complaints" one
drainage complaint has been registered along the downstream route approximately
2,200 feet downstream. This complaint is in regards to flooding of Soos Creek. It is not
reproduced here. According to findings in the Petro Vista Level 9 document, one
complaint was registered of water overtopping Petrovitsky that was found to be caused
by a plugged culvert.
• Road Drainage Problems from KCDOT Roads Maintenance: Not examined.
• USDA Soils Survey: Soil type is cited in the Project Summary
• Wetlands Inventory: No wetlands are mapped on this site or downstream from this site
until it reaches the Soos Creek basin- See map below.
Migrating Rivers studies from DDES: Not examined.
riala.al P.cs: e..n Pcfae•.ce {naps - :.��dn:-slmgrrH h.pl—icr
749 d1AP - Kndorss iwemel Eaposv
I� rep:;;4...ds.mN.�c.9a•r�Maa;.�e.e..trtmM,aP.�wri,
kg K w Canty
root ,ssswa. _
�+a.r
se.n
w
c
�'� x •>er4. r.�
R i
OhP*
Ouipm
LayeR--..Leosw
n M F� mmom**
- � hgrft�gasl
r P.-;
!E rtrxuarv4r p vM, L1 oacd rarbv Ideis
m - LN ia[d Md•ess 4WNs
r LWOM
rwa•d a•eas
r Imes ati �eue anes
r 51—
r qp cw:ty o-a.a9c
' ra,p Corxr'•arr
' ✓ 3esovxInvo,brr
a•eas
- %a IUD iayerw
zc Ames
r I�ca�ver aca
aheY
lfvsae Lavr
f .. n, IlP�flip�i
FIENSUM
Dad
Re'reg+4^�o
nu0l Refill
ICI cixmx r 00555n `• " ' y Pucalfound search_again
Pamak is now doe Add Layer
Vf� PartelHwM-r 4tltlr:ss �sse•+.�+u.4. x�pnr Oistr�ch L�e�Aepenm Mpon
VY
P y
P�- .yprm ecaY•7: 4 M UO M.p
Done a Inrerner; Preceded Mede: OH ",10a,
f�+lntnnet� P,.,. eH Made: Off IOD%
11 _
NAP showing the Soos Greek basin as a wetland and flood plain
12/2412007L:nat B Site Civil UesigniLenora AptslTIR Lenora 07-12-05.doe
Page 15 of 38
Lenora Short Plat
TASK 3: FIELD INSPECT THE STUDY AREA
The downstream inspection was performed on November 26 and again on December 22, this
time during a moderately heavy rainfall.
TASK 4: DESCRIBED THE DRAINAGE SYSTEM, AND ITS EXISTING AND
PREDICTED PROBLEMS
Runoff from the site was not apparent to the naked eye on the day of inspection despite the
moderate rainfall.
1. "DEPRESSION": The drainage path runs off the site in unconcentrated sheet flow at the
northeast corner. The "parcel to the east" has a berm pushed up close to its west property
line. It might be speculated that the berm's purpose is to impede the flow of runoff across its
lawn from the plat -parcel. Runoff is in fact directed to the northeast comer of the plat -parcel by
the natural contours. This berm would serve to further concentrate runoff at the northeast
corner of the plat -parcel; i.e, the northwest comer of the "parcel to the east". The berm does
not act as a dam, as there is ample room for runoff to escape at the north end.
Once clear of the berm, the grade contours show slope to a depression on the lawn of the
parcel to the north of the "parcel to the east". Again, there was no runoff apparent on this rainy
day. There is no evidence that standing water has been a problem.
2. "SWALE": The grade contours indicated slope leaving the depression and flowing northerly
through a broad swath of blackberries and deciduous trees that extend along the back property
lines of the three lots to the north. There is no defined drainage course and no standing water.
ASIDE: This route is apparent only when actually visited on -site. The NAP contours are
ambiguous here, and indicate that the route might be directly east to 118th Ave SE along
the north property line of the "parcel to the east". But on -site it is clear that this is not
the case. There is also no defined drainage course along the north property line of the
"parcel to the east"_
ASIDE: There is a well defined drainage course on the south side of the "parcel to he
east" that does run directly east, across 118th Ave SE, and east again to connect to a
Soos Creek tributary approximately in the BPA right-of-way. This drainage course
existed before the streets were installed and the lots regraded, and still carries water.
However, the contours of the plat -parcel indicate that its runoff does not flow to this
drainage course.
3_ "SWALE": When the downstream contours reach the south property lines of the lots fronting
Petrovitsky, a concrete block wail is encountered. The grade drop is fairly dramatic immediately
12a4rM7LARat & Site Civil aesigntLenore Apts1TTR Lenora 07-12 05_doc
Page 16 of 38
Lenora Short Plat
before reaching this block wall_ Runoff would in theory be deflected by this wall until
overtopping in a shallow swale formed by the earth. Again, there was no runoff apparent on
this day. There is no evidence that runoff has ever overtopped this wall.
4. "SHEET": The grade contours then continue northeast down a driveway to Petrovitsky.
5. "GUTTER": Runoff flows in the street gutter and underlying storm sewer in Petrovitsky. That
street is sloped down to the east for 640 feet until it reaches the bottom of a valley roughly 350
feet across. The storm sewer then outfalls to Soos Creek.
Note: On the day of inspection, the grate of the catch basin at the bottom of the valley was
beginning to clog with debris_ It is easy to see that this would be a continual maintenance
issue.
5. "STREAM": The upper reaches of Soos Creek lie in this valley as does a BPA right-of-way.
Consequently the valley is undeveloped and will remain so_ The stream flows south then east,
across four large single-family home sites that maintain the stream in wooded buffers, then
enters Soos Creek Park. The stream path through the park is heavily buffered by woods. The
stream then leaves the park and crosses two more large, heavily wooded private lots. Soos
Creek has been the subject of intensive and expensive study over the years, and I would not
profess to offer any new insight as to its condition or capacity_ The analysis ends still in Soos
Creek at one mile.
f2/24✓MM-nat & Site Civil DesignW-enora AptslTlR Lenora 07-12-05.doc
Page 17 of 38
OFF-SI'I'.E Ar-4A17.VSIS DRAINAGE SY` X39M rr/"ST.F
SURFACE; wA7'FR DE::ICiN MANUAL, C(?RF REQulRi .Mx:'NT 4#2
Subbarirx
Symbol
B60 ttlatS
Drainage
Component Type.
Name and Size
aype: sheet f ow, awale,
Cream, channel, pie.
pond; S1— diameter.
Drainage
Component
Descrl tlon
dY&ingpe baeln, vepatal4on,
c4+/Pr, depth, type o1 a nsilivo
area, volumo
Slope
%
Distance
from alte
dlschar a
�/ ml 1 ,320 ft.
Exlating
Problems
conelHC[ipn6. Untlar
rtoppl.,g. NOntllnp,
n de6truc1lOn. 6courin9.
as dlmgnvlpn. knciel
Potantlaal
Problems
abservationar of fleld
Inspector, resource
reviewer or resident _
capaclly, pond np.
habitat ar orpsnlam
bank aloi�
on otheroa er Ion
irlhuYary eras, Ilkelihcoci o pro iam.
Overflow pathway,, potential linpnale
!FJ
- f —_
~(
�
SMr•
=i>-� r¢ .rl
��uo- ,J - C�'' ' ^"f �
.S L c y�
mac` s-�`� c7'
••-rt/a�i f
rv.ry /,S "�.. .f-Y..,/' �
v
CO
0
w
CO
Lenora Short Plat
Fjkzme3. Pc&oy*skyAs-built
-r 2 3 N., R- 5 F, W,4f
"' 74"-
M-
4�. -7
4.
—4
t
?:
�41
�7z s S-., p
9.q, "2&
-0 572 391AC411 PF. 5 -.4 9A I. 7
2w*.-!S5,!�-,,,. �' 1� "'PE.
cv-,: c=1 rllE
cry
s'p C,
mkCYZ p Q,az
ROADWAY s-cCrION 4
IT s W �J. �s —s
7.0
q
E
Fw
roP clvllE I
�vs
V�z
16. .370
N07
m -- rV
__ffPWMY EXCAVATION /.O!pc!? CU. YO WY EXCAVATION 4=W EXCAVATIONEMBANKMEM /77' CU. yDa)om Fm VKMEJVT
17
1212412007L:1Piat & Site Civil DesignkLenora Apts%TIR Lenora 07-12-05.doc
Page 19 of 38
Lenora Short Plat
Looking west at the berm from the "parcel to the east"
1. The depression on the parcel to the north of the "parcel to the east"
12/2412007L:1Plat & Site Civil DesignlLenora AptsMR Lenora 07-12-05.doc
Page 20 of 38
6' � �•, ���. .t5�r -, .. �-. �.`ta. 1.
AS -
TV
.11 1. ,
fp
Lenora Short Plat
4. Looking northeast over the block wall to area of sheet flow overland/driveway. No evidence
5. Gutter flow, having gone down Petrovitsky, looking back to the west.
12/24/2007LAPIat & Site civil DesignlLenora Apts1TIR Lenora 07-12-05.doe
Page 23 of 38
Lenora ,5horl flat
6. The stream that crosses Petrovitsky (Soos Creek), to which runoff from the street is
directed. BPA towers in the background.
12124/2007LAPIat & Site Civil DesignlLenora AptsMR Lenora 07-12-05.doc
Page 24 of 38
Petro Vista
Level 1 Downstream Drainage Analysis
Pun
,AAAfi � Cps
FOR: Dale VanDerschelden
21308 Snag Island Drive East
Sumner, WA 98390
253.891,1442
BY: LeRoy Surveyors & Engineers, Inc
1103 Shaw Road
Puyallup, WA 98372
253.848.6608
DATE: September 13, 2002
JOB NO: 6459
ENGINEER: Paul E. Green
CONTACT: Jim Job
EIVIr
4*
F-wAR�Fy SEP 16 Z002
x LAND
USE SERVICES
22420 v W
QHAL t�ia
EXPIRES: 4-22 2003
ExNbic No. 9
Item No. oa
Petro Vista Revel 1 Downstream Analysis 1 King Gourq Heuifg Ex6ner
Table of Contents
Location............................................................................................................ 3
ProjectDescription............................................................................................ 3
SiteDescription.................................................................................................3
Drainage Delineation........................................................................................ 3
Drainage System Description........................................................................... 4
ResourceReview.............................................................................................. 4
Soos Creek Basin Plan................................................................................. 4
Reconnaissance Report No. 2, Soos Creek Basin ........................................ 5
FEMAFioodplain Map., ... I ........ I .................................................................... 5
Sensitive Areas Folio and Wetland Inventory ................................................ 5
SoilSurvey Map............................................................................................ 5
DrainageProblem......................................................................................... 5
Field Inspection of the Site................................................................................ 6
Conclusions...................................................................................................... 6
Petro Vista Level 1 Downstream Analysis 2
Location
The property is located in Renton, King County, Washington, at the SE
corner of S.E. Petrovitsky Road and 118tf Avenue S.E. in Section 33, Township
23 N, Range 5 E, W.M. The site address is 11925 S.E. Petrovitsky Road.
Project Description
The property owners are proposing to develop and subdivide a 3.83-acre
site into 23 single-family residential lots.
Site Description
The property consists of King County Parcels 6196600380 and
--. 6196600381. It is bordered to the north by S.E. Petrovitsky Road (S.E. 176th
St.), to the west by 1181" Ave. S.E., and to the east by a BPA power line right-of-
way. There is an office building, a garage, a shed and an equipment yard
located on the eastern half of the property. The land slopes down towards the
center from the buildings, and the western and southern sides to create a small
depression located in the north half of the property. This depression contains a
small (approximately 0.12 acre) Class 2 Wetland. The onsite wetland is
dominated by Scrub -Shrub vegetation [predominantly red -osier dogwood
(Comus sericea)] with a developing forested class [predominantly Oregon ash
(Fraxinus latifolia) and black cottonwoods (Populus balsamifera)]. The upland
has areas of Himalayan blackberries (Rubus procerus), mixed young forest
dominated by Douglas firs (Pseudotsuga menziesh) and black cottonwoods, and
open grassy areas. On the east side of the buildings, the land slopes down to
the eastern border. This hillside is dominated by black cottonwoods with an
understory dominated by trailing blackberries (Rubus ursinus) and snowberries
(Symphoricarpos albus).
Exhibit "A" shows the site vicinity map. Exhibit "B" shows the site plan
with topographic contours.
Drainage Delineation
The project is located in the upper portion of the Upper Soos Creek
drainage subbasin. For the purpose of this downstream analysis, an 1113-acre
drainage area (291 times as large as the development site) is delineated by
setting the downstream point at approximately 0.5 miles from the development
site. (Exhibit "C" - Drainage Delineation Map).
Petro Vista level 1 Downstream Analysis 3
Drainage System Description
The stormwater runoff from the site will be collected in a closed pipe
network and stored in a detention pond before releasing into an on -site wetland
at flow rates less than or equal to the pre -developed rates.
The onsite wetland is 5 ft deep with a storage volume of 64,890 cubic feet.
The tributary area to this wetland is relatively small, largely confined within the
property area. The wetland does not appear to have been overflowed in recent
history as evidenced by lack of obvious outlet and high water mark. However,
when overflow occurs, the water would run over the sidewalk into the closed pipe
system along Petrovitsky Road. The stormwater entering this closed pipe system
would travel approximately 275 feet to the east and end with a 36" culvert that
discharges into an off -site wetland.
The offsite wetland is primarily a reed canarygrass meadow (Phalaris
arundinacea), with isolated Scrub -Shrub clusters [predominantly spirea (Spirea
douglasii) and Pacific willow (Salix lucida)] and a Scrub -Shrub fringe
[predominantly Himalayan blackberry and western crabapple (Malus fusca)]. The
majority of the wetland is located in the BPA transmission line R-Q-W.
The stormwater meanders in a southeasterly direction through the off -site
wetland and the BPA R-Q-W for approximately 275 feet and exits the offsite
wetland through an 18" diameter culvert at the south edge. At this point, it begins
to change direction and travels easterly for apvroximately 700 feet to a 36 inch
diameter corrugated metal culvert under 122 Avenue. This is where it meets
the headwaters of the Big Soos Creek and continues in a southerly direction.
Resource Review
The following information resources have been reviewed in preparation of
the analysis.
Soos Creek Basin Plan
This report is a lengthy and comprehensive document that describes the
existing conditions in Soos Creek Basin and predicts the potential impacts of
future land uses on watershed ecosystem. The report provides recommended
plans and alternative solutions to deal with the problems associated with urban
development. The problems identified in the upper Soos Creek basin include
increased peak flows, flooding and undersized channels and culverts. However,
these problems do not appear to occur in the close vicinity of the site or in direct
downstream area. Part of the report that is relevant to the upper Soos Creek
area is attached as Exhibit T".
Petro Vista Level 1 Downstream Malysis 4
Reconnaissance Report No. 2, Soos Creek Basin
This report was written in 1986 when rapid urban development in this area
just began. The report identified some surface water problems in Soos Creels
Basin and proposed some drainage improvement projects to mitigate those
problems. No specific problem or mitigation project was identified in the close
vicinity of the site. The report is attached as Exhibit "E".
FEMA Floodplain Map
The proposed development site is not within a floodway or a floodplain,
while the offsite wetland to the east and a large downstream area along the Big
Soos Creek is classified as Zone AE, as indicated by the floodplain map
(attached as Exhibit "F).
Sensitive Areas Folio and Wetland Inventory
The following categories of sensitive areas have been reviewed: Coal
Mine Hazards, Erosion Hazards, Landslide Hazards, Seismic Hazards, National
Wetland Inventory Wetlands, and King County Wetland Survey. None of above -
mentioned sensitive areas exist within the development site. A seismic hazards
area and a 134-acre King County wetland exist approximately 0.1 mile east of
the property. A small NWI wetland exists approximately 0.2 mile downstream to
the southeast. An erosion hazards area exists approximately 0.4 mile to the
southeast. The sensitive areas folio map is attached as Exhibit "G".
Soil Survey Map
The soils on the property are mapped as Alderwood gravelly sandy loam,
6-15% slopes by the Soil Conservation Service (U.S. Department of Agriculture,
1973, see Exhibit "H"). The soil types have been confirmed by site visits.
Drainage Problem
d .
The King County Water and Land Resources Division provided a list of
complaints related to drainage problem in the general area of the proposed
development site. We have checked the locations of the problems and did not
find any problem that had originated from or directly connected to the site. The
closest location where flooding problem once occurred was at 118TH Ave SE
cross Petrovitsky Road to the north in November 2001. The problem appeared
Petro Vista Level i Downstream Analysis 5
to be caused by partial clogging of one or more downstream culvert entrances
and were considered normal for a heavy and extended rainfall. This problem
was unrelated to the proposed development site by any means. The complete
list of complaints and the original record of above -mentioned complaint are
attached as Exhibit "I".
Field Inspection of the Site
We visited the site on two occasions, February 15, 2000 and February 22,
2000. It was cloudy but dry the first visit to the site. It was raining moderately on
the second visit. On both occasions, there was no standing water observed in
the on -site wetland. The actual drainage system appeared to match the
a
description in the plan. No obvious nuisance problem could be identified at the
site and close downstream area.
Conclusions
The on -site wetland provides a sufficiently large storage, evaporation and
infiltration area for its relatively small tributary basin, which keeps the onsite
surface runoff from releasing into downstream. Under normal circumstances, the
on -site drainage system is effectively isolated from the offsite drainage system in
terms of hydraulic connection by surface water. The construction of the
detention pond and release control structure will limit the runoff rates to the on -
site wetland to the predeveloped level. So, even overflow from the wetland to
downstream occurs in a big storm event, the flow rate will be unlikely to exceed
the predeveloped flow rate. Based on this analysis and review of available
information and our field inspection, we anticipate that the site development will
not alter the existing drainage and will have no negative impact on downstream
hydrology.
Petro Vista Level i Downstream Analysis 6
I
Exhibit "A"
Site Vicinity Map
�M1 ky _R
SIIT
°p sT I
i H rT SE Yff-" g1 J' -
t T3t 0. ST}i?�
SE 1767. 3T SE _ 7i2Q�RO`
a
SE
UyM(Wlr � 18f17Ffl S 1
SST �yQ
g S r -882;NO-3 5E + S' T �L
8 1.8I. _ iJ T K �$T
PL
BE
��--
N
d .? 9DT11 ST b i' x
r
A
3E 188TH sT ,: x
'�ciws ou TY IS�PHTER,�O
Petro Vista Level 1 Downstream Analysis
Exhibit "B"
Petro Vista Site Plan
Exhibit "C"
Drainage Delineation Map
Petro Vista Level 1 Downstream Analysis
7— 1
fj
jj
4-r'
jil
I If
'17
ep
jj 4
rT �V'ra
I �4-
j JI j
,U —Y---
-AD
Exhibit T"
Soos Creek Basin Plan (Partial)
r,
a,
1.
Petro Vista Level 1 Downstream Analysis
TABLE OF CONTENTS
PAGE
4-
Preface Pages
F -
SEPA FACT SHEET . . . , .
TABLE OF CONTENTS . , . . *-
LISTOF FIGURES . . . . . . . . . . . . . . . .
;
vi;
LISTOF TABLES . . . . . . . . . . . . . . .
. . . . . . . . . . .
. vi i
DOCUMENT ORGANIZATION . . . . . . . . . . . . .
. . . . . . . . . .
vi i i
SUMMARY OF RECOMMENDED PLAN AND ITS IMPACTS
CURRENT AND FUTURE CONDITIONS: Affected Environment . . . . . . . .
. 13
s. Description of Watershed Area . . . . .
.�.
13
Water ', , , , ', , , , , , .,
,- .
17
Hydrology and Hydraulics . . . . . . . . .
. . . . . . . . . . .
. 17
Surface Water Quality . . . . . . . . . .
. . . . . . . . . . .
. 37
Groundwater . . . . . . . . . . . . . . .
. . . . . . . . . . .
. 42
Earth ...............................
49
Geology . . . . . . . . . . . . . . . .
. . . . . . . . . . .
. 49
Erosion, Transport, and Deposition of Sediment
, . . , . , . .
. 52
Plants and Animals . . . . . . . . . . . ...
. . . . . . . . . . .
. 59
'RECOMMENDED PLAN . . . , . . . . . . . .. .
. . . . . . . . . .
.. �,,_L5D
k Introduction . . .
75
Organization . . . . . . . . . . . . . .
. . . . . . . . . . .
. 76
Area -Specific Recommendations . . . . . . .
. . . . . . . ,j
- Basinwide Recommendations . . . . . . .
. . . . . . . . .
Citizen Advisory Committee Opinions . . . .
. . . . . . . . . ,
150
Implementation . . . . . . . . . . . . . . .
. . . . . . . . .
152
ALTERNATIVE SOLUTIONS AND IMPACTS: Alternative
Solutions, Significant
ak Impacts, and
Mitigation . . . . .
157
Introduction .. . . . . . . . . .
. . . . . . . . . . .
. 157
,- Area -Specific Alternatives . . . . . . . . .
. . . . . . . • . . .
. 157
Pasinwide Alternatives . . . . . . . .
. . . . . . . . .
. .192
Generalized Impacts of Alternative Solutions
. . . . . . . . . ...
. 208
BACKGROUND INFORMATION AND REFERENCES .
. . . . . . . . . .
. 251
Introduction . . . . . . . . . . . . . . . .
. . . . . . . . . . .
. 251
List of Elements of the Environment . . . .
. . . . . . . .
.
251
Distribution List . . . . . . . . . . . .
. . . . . . . .
253
HSPF Flow Summary . . .
254
Recommended Implementation Schedule . . . .
. . . . . . . . . . .
. 254
County Costs for Land Use, Regulatory, and
Programmatic Recommendations . . . . . .
. . . . . . . . . .
268
u Alternatives Evaluation Criteria . . . . . .
. . . . . . . . . . .
. 276
References . . . . . . .' , . .
, . . , . . , , . .
. 277
_ Draft EIS Comments and Responses . . . . .
. . . . . . . . . . .
. 761
LIST OF FIGURES
FIG.
NO.
TITLE
PAGE
1
Proposed Soos Creek Basin P1an1FEIS Organization
. . . . . . ..
ix;
2
Soos Creek Basin Planning Area . .
.
2'
3
Recommended Land Use and Regulatory Solutions
5
4
Recommended Stream Improvement Projects . . . . .
. , . . . .:.
9
5
water Features . . . . . . . . . . . . . . .
.
15
6
Sgos Creek 1985-Land Use/Land Cover . . . . . .
19
7
Soos Creek Future Land Use/Land Cover . . . . . .
. . .
21
8
1985 Peak Flows by Subcatchment.. . . . . . .
. . . .
25
9
Ratio of Maximum Buildout to 1985 Two -Year Flows
. . . . . . .
27
10
Future'Peak Flows by Subcatchment . . . . . . . ...
29
11
Significant Flow --Related Problems . . . . . . .
12
Water Quality Alert Areas . . . . . . . . . . . .
. . . . .
3
13
Significant Surface Water Quality Problems . . .
. . . . . . .
43
14
Generalized Geologic Cross Section, Soos Creek Basin
Region
45
15
Groundwater Concern Areas . . . . . . . . . . . .
. . . . . . .
47 --
16
Generalized Geology of the Soos Creek Basin Region-
. . . . . .
51
17
Significant Erosion and Sedimentation Problems .
. . . . . . .
55
18
Timing of Salmon Fresh Water Life Phases
in Green-Duwami sh Basin . . . . . . . . . . . .
. . . . . . .
60
19
Aquatic Habitat Problems . . . . . . . . . . . .
. . . . . . .
73
20
Six Regions for Area -Specific Analysis . . . . .
. . . . . . .
77
21
Upper Soos Basin -Recommendations . . . . . . . .
. . . . . . .
80
22
Little Soos Basin Recommendations . . . . . . . .
. . . . . . .
66
23
Jenkins Basin Recommendations . . . . . . . . . .
. . . . . . .
91
24
Regionally Significant Resource Areas:
Lower Density Maintenance Areas . . . . . . . .
. . . . . . .
95
25
Covington Basin Recommendations . . ... . . . . .
. . . . . . .
101
26
Soosette Basin Recommendations . . . . . . . . .
. . . . . . .
107
27
Lower Soos Basin Recommendations . . . . . , . .
. . . . . . .
III
28
Stream Corridor Management Areas . . . . . . . .
. . . . . . .
117
29
Stream Reaches in Roadside Ditches . . . . . . .
. . . . . ...
127
30
Recommended Monitoring Sites . . . . . . . . . .
. : . . . . ..
131
31
Approximate Stream Classifications for
Determining Stream Buffers . . . . . . . . . . .
. . . . . . .
137
32
Upper Soos Basin Alternatives . . . . . . . . .' ...
. . . . . .
158
33
Little Soos Basin Alternatives . . . . . . . . .
. ... . . . .
165
34
Jenkins Basin Alternatives . . . . . . . . . . .
. . . . . . .
170.
35
Covington Basin Alternatives . . . . . . . . . .
. . . . . . .
177
36
Soosette Basin Alternatives . . . . . . . . . . .
. . . . . . .
182
37
Lower Soos Basin Alternatives . . . . . . . . . .
. . . . . .
188
s
LIST OF TABLES
TABLE
NO.
TITLE
PAGE
I.
Soos Creek Salmon Escapement Annual
Averages, 1966-71
.
. 61
2
Soos Creek Sea -Run Trout Escapement
..,
62
3
Riparian Forest in the Soos Creek Drainage
..: 63
4
Large Organic Debris in Urban and Rural
Streams
. . . . 67
5
Upper Soos Implementation Silmmary . .
. . . . .
. . . . .. . 84
6
Little Soos Implementation Summary .
. . . . .
. .. . . . . . 89
7
Jenkins Implementation. Summary . . .
. . . . .
. . . . . . . 98
8
Coyington Implementation Summary . .
. . . . .
. . . . . . . 105
9
Soosette Implementation Summary . . .
. . . . .
. . . . . . . 109
10
Lower Soos Implementation Summary . .
. . . . .
. . . . . . . 114
it
Ba'sinwide Recommendation Implementation
Table .
. . . . . . . 148
12
HSPF Flow Summary . . . . . . . . . .
. . . . .
. . . . . . . 254
13
Recommended Implementation Schedule
. . . . .
. . . . . 264
14
County Costs for Land Use, Regulatory,
and
Programmatic Recommendations . . . .
. . . . .
268
DOCUMENT ORGANIZATION
,,. This plan is a combined plan and programmatic FEIS. This format was chosen to
facilitate review and ensure that the ultimate users of the plan will have
direct access to discussions of A mpacts and mitigating measures.
Figure I shows the organization of this document. The document begins with a
short summary of the basin plan and FEIS. Next, the Current and Future
s- Conditions section summarizes the detailed analyses of surface water issues in
the system. This section corresponds to an "Existing Conditions" or "Affected
aT Environment" discussion of a stand --alone FEIS.
The Recommended Plan section then identifies the preferred course of watershed
management, including a preferred approach for each identified problem. A.
discussion of preferred alternatives for area -specific conditions in six regions
of the Soos Creek system is followed by preferred alternatives on a basinwide
level. The cost and priority of the preferred alternatives are presented with
preferred implementation methods. This section also includes the opinions of
the Soos Creek Basin Plan Citizen Advisory Committee.
The Alternative Solutions and Impacts section identifies and compares
alternative solutions for area -specific problems in six regions of the Soos
Greek system, as well as basinwide problems. This section identifies preferred'
alternatives. Finally, the generalized environmental impacts of and mitigation
for these alternatives, including the No -Action and Preferred Alternatives, are
discussed in this section:
The Background .information and References section documents the relevant
elements of the environment for HIS analysis, the SEPA distribution list for
this.document, detailed tables of modeled flows, recommended implementation
schedule, costs for land use, regulatory, and programmatic recommendations,
., recommendations ranking criteria, and a list of references. Finally, public
comments on the DEIS are shown with responses.
SUMMARY OF RECOMMENDED PLAN AND ITS IMPACTS
INTRODUCTION
SUMMARY OF RECOMMENDED PLAN AND ITS IMPACTS
INTRODUCTION
E
The Soos Creek Basin Plan was developed under the King County SWM Program. The
a plan covers the Soos, Jenkins, and Covington Creek Basins in south King County
(Figure 2). using field observations, the results: -of past studies, and computer
LL modeling, the- Soos Creek Basin Plan evaluates toddy's stream flows, erosion,
sediment deposition, stream habitat, and water quality. The plan then predicts
how these conditions will change as the predominantly rural Soos Creek area
i develops to suburban and urban densities. Finally, the plan recommends ways to
reduce future resource damage and repair current surface water -related problems.
The Soos Creek system exemplifies the difficulty of protecting a natural
resource while simultaneously accommodating rapid population growth. Parts of
the basin are currently rural and their streams are in good or excellent
'. condition. Yet elsewhere, the basin is experiencing some of the fastest
development in King County and displays many of the unintended problems
' associated with that activity. These problems include flooding, erosion,
sedimentation, destruction of fish habitat, and degraded water quality.
The results of this basin plan suggest that such consequences are a virtually
Inescapable byproduct of urban .growth. Mitigation imposed on new development,
or correction of preexisting conditions, can lessen their impact. Yet stable
stream channels, a healthy fishery, and clean water depend on the whole
integrated function of a watershed. From the ground that first receives the
rainfall to the channels that convey it downstream, no element is extraneous.
Mitigation can replace a portion of functions lost when development takes
place. But there are no data to suggest that all such functions can be replaced
on the scale of a large watershed or even in a small subcatchment. The regional
decisions on growth are therefore decisions on the future of our stream systems
and quality of their waters as well: where is degradation tolerable, how much
cost are we willing to accept for at most partial protection, and where are the
resources so valuable and unspoiled that their protection should be paramount?
This basin plan seeks to provide some of those answers, using a full spectrum of
L analytic tools and professional expertise.
( CONDITIONS IN THE SODS CREEK SYSTEM
{ OVERVIEW
Much of the Soos Creek system- currently is rural and its streams are in
relatively good condition, partitularly in the Jenkins and Covington Creek
( Basins. However, the Soos Creek area is one of the fastest growing areas in
King County. The surface water effects of rapid development have only recently
s become evident. The Soos Creek system's extensive and relatively undisturbed
network of streams, wetlands, lakes, forest cover, and large areas of highly
infiltrative outwash deposits have up to now masked these effects in most areas.
4
SUMMARY OF RECOMMENDED PLAN AND ITS IMPACTS
CONDITIONS IN THE SOOS CREEK SYSTEM
Surface water management i� the Soos Creek system presents a dual challenge; to
reduce the surface water problems associated with suburban growth in the Soos
Creek Basin to the west, and to preserve the elements of the natural hydrology
and habitat in the more easter`.ly basins of Jenkins and Covington Creeks that are
,- critical to the high quality, biological diversity, and productivity of this
stream system. Recommendations reflect the differences in development -related
impact between these two parts of the system. In the west, the recommendations
seek to correct and avoid the most damaging of those impacts. 'In the east, the
goal of resource -preservation is far more challenging, because the full spectrum
of development impacts is -.so difficult to control. Yet the resource at risk
c here is of critical value not only in King County but also in the Puget Sound
Region as a whole.
CONDITIONS
Present stream flows cause periodic flooding of three County roads, a" parking
lot, four houses, and two apartment buildings. In the -future, this flooding
will increase in both frequency and severity.' Floodplains in most parts of the
system will widen due to increases in peak stream flows, predicted to be more
than two times larger in some areas.
One major erosion site is -a potential future threat to'a-house and another is
undermining a County road, Erosion in two small-, steep tributaries contributes
to downstream sedimentation, particularly at the Green River Hatchery. As peak
flows increase in the future, the amount of sediment eroded and transported in
the mainstem of Soos Creek is. -expected to roughly double.
Only localized water quality degradation has been observed .in the Soos Creek -
system, including high fecal coliform levels in Little Soos Creek and high
` nutrient levels in lakes. Nutrients, sediment, and other pollutants carried by
•° stormwater runoff could pollute domestic water supply wells in areas with coarse
gravelly soils. In the future, nonpoint pollution of this type is predicted to
become an increasing threat to the use of the streams for water supply, fish
habitat, and recreation.
For its size, the Soos Creek system includes some of the most diverse and
abundant salmanid habitat in the southern Puget Sound region. Because of this
high -quality habitat and' the Washington State Department. of Fisheries' Green
River Hatchery in lower Big Soos Creek, the Soos Creek system is a significant
contributor to the $19 million annual value of the Green River fishery (Grette
f and Salo, 1966).
Even with many examples of excellent habitat, the habitat is starting to exhibit
the systemwide effects of rapid development as well as localized habitat
problems. These problems include livestock -related bank trampling, wetland
filling, channelization, loss of forested stream corridors, fish' passage ,
barriers, dewatering, and damage from high flows and sediment movement. These
habitat problems are expected to worsen in the future as both human intrusion
into previously undisturbed stream corridors and stormwater runoff increase.
SUMMARY OF RECOMMENDED PLAN AND ITS IMPACTS � --
RECOMMENDATIONS
RECOMMENDATIONS
The basin plan recommends a comprehensive basin management program that will
correct significant surface water'. problems and provide substantially greater
protection for the basin's valuable resources than current County programs.
Because no single approach effectively addresses the broad range of surface
water issues in the basin, a combination of basin management approaches is
recommended, including:
° Land Use. -Controls: Establishment of maximum densities of one unit Tfive acres
in some areas to protect significant fish habitat (Figure 3);
° Regulations: Adoption of development controls including:
- Establishment of buffers of waterside vegetation to protect streams and
wetlands, .
-- Floodplain development and clearing limits, and
- Requirements that new developments install improved water quality and
stormwater control facilities;
° Education and Incentives: Initiation of education and incentive programs to
T encourage public participation in stream protection;
° Stream Steward: Establishment of a new "Stream Steward" position to conduct
education and citizen involvement programs', facilitate project installation,
and monitor basin management activities in the Soos Creek Basin;
° Enforcement and Penalties: Increase of County Code enforcement and stronger
penalties for code violations;
° Monitoring and -Plan Update: Conduct basin monitoring to evaluate the
program's long-term success and identify changing conditions that require
adjustments in basin management.
Projects: Installation of stream improvement projects including:
- 60 small-scale stream improvement projects, including projects for
streambank stabilization and revegetation-, fencing of livestock -damaged
reaches, improvement of instream habitat diversity, removal of fish -passage
barriers, and repair of channel alterations; and
- thirteen flow and erosion -related projects with appropriate mitigation such
as bank revegetation, onsite habitat replacement, and fish passage facili-
ties, including:
* one regional detention facility to control flooding and erosion on
Soosette Creek;
* a channel enlargement project to reduce flooding and improve habitat on ,
Little Soos Creek;
* a project to stabilize an eroding streambank of Big Soos Creek below a
County road;
d
SUMMARY OF RECOMMENDED PLAN AND ITS IMPACTS
ENVIRONMENTAL IMPACTS OF RECOMMENDED PLAN
* larger or parallel culverts -at SE 240th St., 132nd Ave. SE, SE 269th St.,
120th Ave. SE and Petrovitsky Road, and 164th Ave. SE to reduce flooding
and improve fish passage;
* two flood -channel stabilization and protection projects on Upper Big silos
and the Meridian Valley tributary;
* two detailed studies of R1D alternatives on the Soosette and Meridian
Valley tributaries;
* raising of two flood -prone County roads; and
* tightline pipes to convey all or part of the water down steep eroding
a. slopes at four sites (Figure 4).
BASIN PLAN IMPLEMENTATION COST AND SCHEDULE
The estimated cost of the recommended projects .is $5.4 million. The costs of
implementing the plan;s 50 other recommendations ranges from $1.3 million for
staff and start-up costs in the first year to $478,600 in annual costs for
ongoing basin management programs. If the recommendations under the Surface
Water Management (SWM) Division's responsibility were funded using existing SWM
revenues from the basin, plan Implementation would span 16 years during which
property and resource damage would continue.
�To shorten the implementation period to five years, a basin -specific surcharge
is recommended to be considered during King County Council review of the SWM
Program in 1990191. If this surcharge is adopted, the SWM fee for a single
family residence during the. five year implementation period would, range from $77
In the first year to $59 for the second through fifth years compared to the
current fee of $29 per year. After five years, a permanent $3 increase in the
$29 fee could pay for continuing basin management programs.
' ENVIRONMENTAL IMPACTS OF RECOMMENDED PLAN
NO -ACTION ALTERNATIVE
If no action is taken, flows will more than double in some reaches and human
alteration of the stream system will increase as the basin reaches build -out
conditions. These flows will worsen property damage and safety hazards due to
flooding and' erosion. The predicted consequences of these changes include a
doubling of the amount of sediment eroded and transported in the mainstem,
decreased beneficial use of wafter due to degraded water quality, and eventual
i reduction in fish populations due to aquatic habitat damage.
BASIN PLAN IMPACTS
In the long term, the watershed management measures in this plan are expected to
have substantial positive environmental effects. Individual plan recommen-
SUMMARY OF RECOMMENDED PLAN AND ITS IMPACTS
ENVIRONMENTAL IMPACTS OF RECOMMENDED PLAN
dations, however, could have some localized negative environmental impacts.
Proposals for .low densities, floodplain encroachment limits, onsite RID stan-
dards, clearing restrictions, vegetated waterside buffers adjacent to streams
and wetlands, increased code enforcement and penalties, and incentives for
resource protection would reduce future peak flow increases, and consequently
would reduce erosion and aquatic habitat damage. Limits to livestock access to
streams would reduce streambank erosion, resulting in reduced sedimentation of
spawning gravels. Proposed education programs and water quality requirements
for onsite RID facilities would reduce water quality degradation, resulting in
reduced impacts on beneficial uses, including aquatic habitat. Water -quality
degradation also would be reduced through aquatic habitat/water quality enhance-
ment projects. Increased review of onsite septic systems in areas with highly
infiltrative soils also could reduce the risk of surface and ground water pollu-
tion.
WATER
The proposed regional RID facility and any RID facilities that are recommended
after detailed study of alternatives would reduce downstream peak flows and, as
a consequence, reduce downstream flooding and erosion. RID facilities in
wetlands could improve downstream water quality through' the settlement of sedi-
ments and attached pollutants but as a result could degrade water quality in
the wetland. These facilities also would create an instream impoundment,
affecting sediment deposition patterns and potentially degrading upstream
aquatic habitat.
EARTH
Construction -related erosion and sedimentation would occur during installation
of tightline and conveyance pipes, construction of RID facilities, and bank
stabilization. Once complete, however, these improvements would reduce channel
scour and bank failures by reducing.peak flows or bypassing erodable areas.
Regional RID facilities would change sediment transport and deposition patterns
which could cause sediment to settle in the impoundment area and to be
resuspended periodically and deposited downstream.
PLANTS AND ANIMALS
The outlet structures for the proposed instream RID facility and facilities
that are recommended for study may be impassable to fish during flood events.
These structures would. be impassable no more than ten percent of the time during
the months of adult saLlmon migration. These facilities would affect primarily
resident fish because the proposed instream ponds are either outside or at the
upper limits of the anadromous zone. The instream detention sites may strand
juvenile and adult fish as flood flows recede. Sediment could settle in
spawning gravels in impoundedreaches► In wetlands used for RID facilities, the
increased water elevation and greater variability may cause a shift in the
diversity, number's, and community structure of plant and animal species,
Instream habitat may be disrupted temporarily by the noise, erosion, and acti-
vity associated with construction.
SUMMARY OF RECOMMENDED PLAN AND ITS IMPACTS
ENVIRONMENTAL IMPACTS OF RECOMMENDED PLAN
LAND AND SHORELINE USE
Local increases in floodplain width would occur in Soos Creek Park and on
undeveloped land in other areas,. Proposed regulatory changes that address these
increases and other proposals to protect stream corridprs, maintain lower
densities, limit clearing, and protect regionally significant aquatic habitat
areas would limit the opportunity for development in flood -prone areas. Density
limits -would reduce the density of land use in substantial areas within the
system. These limits apply in some areas designated as urban on the
—,Comprehensive Plan map and conflict with zoning in some areas. The limits would
reduce some landowners' abilities to develop land to higher densities, and thus
may have an economic impact on these private landowners. Residential areas
adjacent to project sites may be disrupted temporarily by construction -related
traffic and noise. Ongoing disruption of adjacent areas would occur during
facility maintenance activities. Shoreline access at some project sites also
would be limited.
ffl:-DI14 �'3L•i WId
T_ Intermittent congestion of neighborhood streets and arterials may occur during
construction of projects. Temporary -traffic disruption may occur during
construction of the two road -raising projects, but blockage during flood events
' would be eliminated.
PUBLIC SERVICES AND UTILITIES
Regional RID facilities and subbasin-specific onsite RID requirements would
increase the County's maintenance'responsibilities. However, County programs
already are established to maintain existing and new RID facilities. Land use
and regulatory proposals would require County administration, including review
of development proposals, inspection, and enforcement.
l
r CURRENT AND FUTURE CONDITIONS
DESCRIPTION OF WATERSHED AREA
f �
CURRENT AND FUTURE CONDITIONS;' Affected EnVironment
DESCRIPTION OF WATERSHED AREA
LOCATION
The Soos Creek system lies in south King County, north and east of the Green
River and southeast of the City of Renton. Big Soos Creek originates in the
northeast corner of the glacially molded upland known as the Covington Drift
� Plain and joins the Green River just east of Auburn. Covington and Jenkins
Creeks are its main tributaries.
STREAMS
5
The Soos Creek system consists of mainstem Big Soos Creek and some 25
tributaries. The system has over 60 miles of stream and drains an area of
approximately 70 square miles (44,800 acres) (Figure 5).
All major tributaries in the Soos Creek system have similar physical
characteristics. All drain flat to rolling terrain in the upper basin,
+ converging below River Mile (RM) 5.0 of Big Soos Creek. Marty reaches of the
upper plateau flow through extensive wetlands where pools are deep and
` velocities slow. The upper sections of Big Soos are characterized by heavily
wooded riparian corridors interspersed with pastures and increasing residential
£ development. Below RN 5.0, the gradient increases sharply as the stream flows
through a deep canyon with long riffles and sparse pools. In these lower
reaches, Big Soos Creek varies between 30 and 40 feet in channel width.
Surface water in the Soos Creek system is carried largely in natural stream
f. channels, typically with culvert crossings in the basin's upper regions and
bridge crossings in the lower. The Soos Creek Basin has no regional retention/
detention (RID) facilities, but there are individual'detention ponds on platted
and commercial building sites.
WETLANDS
` The wetland system is quite extensive and includes all classes of freshwater
4 wetlands --predominantly open water, scrub -shrub, and forested, with some
emergent marsh, wet meadow, and bogs. The King County Wetland Survey and Basin
{ Reconnaissance Report list over 225 wetlands in the Soos Creek system --a total
of 2,076 acres, or about 4.6 percent of the land area in the basin (King County,
1986, 1987a, 1987b).
Most wetlands of the Soos Creek system are "riparian" --associated with streams--
and are located on the flat or gently,rolling'upper plateau of the watershed.
In the Jenkins and Covington Creek Basins, much of the -upper plateau is
underlain by varying depths of outwash material over till soils. The water
d = table in this area often is close to the surface. As a result, small pocket
wetlands appear where potholes and swales intersect the groundwater table. In
E the upper Jenkins Creek Basin, for example, the headwaters.of many streams are
1 .
CURRENT AND FUTURE CONDITIONS
DESCRIPTION OF WATERSHED AREA
small, linear wetlands that formed in glacial troughs. As these streams travel
toward the mainstem, many disappear into porous gravel deposits, only to
reappear as wetland pockets farther downslope.
LAKES
The lakes of the Soos Creek system --Lake Youngs, Lake Meridian, Shadow Lake,
Lake Sawyer, Lake Wilderness, Pipe Lake/Lake Lucerne, Ginder Lake, Ravensdale
Lake, and take Morton --are used primarily for recreation and aesthetic -
enjoyment. Six of them.have boat ramps, and County parks lie on the shores of
Lakes Meridian; Sawyer, and Wilderness.
CURRENT AND FUTURE LAND USE
Overview
The north and west portions of the Soos Creek Basin west of Big Soos Creek have
a pattern of urban density subdivisions, commercial centers, and scattered
single-family homes. The most developed areas are along Kent-Kangley Road and
near the -western boundary with -Kent and Renton. To the west of Big Soos Creek
and south of Kent--Kangley Road, the Soos Creek Basin is predominantly rural,
with small farms and scattered residences.
The Jenkins and Covington Creek Basins, in the south and east parts of the Soos
Creek system, mainly contain hobby farms and rural.residences. Second -growth
forests, are common. Sand, gravel,. and clay are mined in the hills east and
northeast of Black Diamond, and coal is mined near the northeast corner of
Cinder Lake. The major developed areas surround Lakes Wilderness and Pipe/
Lucerne, the communities of Covington and Ravensdale, and the City of Black
Diamond.
Although much of the Soos Creek area remains rural, its population growth,
number of subdivided lots, and permits for residential units show it to be one
of the fastest -growing areas in King County. The late.1970s saw increased devel-
opment, particularly in the western Soos Creek Basin, and the effects of urban-
ization on surface water are already evident. Greater development promises to
exacerbate effects such as increased flows and consequent erosion, and human
alteration of streams and wetlands,
Maps; Description and Data Sources
The current and future land use maps provided data for computer -based hydrologic
simulations. Current land cover data were taken from aerial photographs, Kroll
maps, Sensitive Area'Map Folio (amended in 1987), King County Wetlands
Volume II, (1983), U.S.G.S. 1:24,000-quadrangles, Soil Conservation Service
maps, field investigations, and other studies. Future land cover data were
taken from land use plans of the Cities of Kent and Black Diamond, the 1985 King
County Comprehensive Plan, the Soos and Tahoma/Raven Heights' Community Plans,
current zoning, and other studies.
1a -
r
CURRENT AND FUTURE CONDITIONS
WATER
•i
For comparison with future land use changes, 1985 land use was considered the
i baseline or "current" land use (Figure 6). The map of future land use (Figure 7)
is based on a high -density land use alternative. This land use may be con-
sidered the "worst --case" land 'use scenario because it assumes the highest fore-
seeable level of development, resulting in the highest foreseeable runoff.
WATER
HYDROLOGY .AND HYDRAULICS
Introduction
The Soos Creek system is hydrologically complex with many lakes, wetlands, and
interactions of surface water with groundwater; Existing development in the
basin ranges from rural to high -density. urban. A number of flow -related prob-
lems have been associated with this urban development. .Understanding the
hydrologic mechanisms behind these pFob.lems is the key to solving them and pro-
vides the basis for predicting where other surface water problems will occur as
development continues.
This section discusses the hydrology of the Soos Creek system under existing-
(1985) land use and future build -out conditions -in the absence of recommended
mitigating measures. The relevant runoff mechanisms and factors that affect the
Soos Creek Basin are discussed first, followed by a description of the basin
r_ hydrology and hydraulics under 1985 land use, the conditions under future build -
out land use, and a list of specific flow -related problems.
Runoff Mechanisms
The hydrology of the Soos Creek system was characterized by many field visits,
the use of a rainfall/runoff simulation computer model, and a hydraulic computer
?. model. The simulation model used was the Environmental Protection Agency's
Hydrologic Simulation Program Fortran (HSPF). HSPF was used to portray
the hydrology of the basin under current conditions and examine the effects of
build -out conditions on hydrology. The U. S. Army Corps of Engineers NEC-2
hydraulic model was used to compute flood plains and determine the extent of
flooding in flood -prone areas.. Input parameters for the models used in this
analysis are outlined in the Soos Creek Basin Calibration Reports (King County,
' 1987c) and are available upon request from King County.
Soils were grouped into three broad categories for hydrologic purposes: outwash,
r till, and wetlands (see Geology section for a complete discussion of soils).
outwash soils consist of sand and gravel deposits that have high infiltration
rates. Rainfall in these areas is quickly absorbed and percolates to the
groundwater table. Creeks. draining these areas typically intercept the.
groundwater table and receive most of their flow from groundwater discharge.
;. the response in the creeks after a storm is therefore slow, with the peak flow
in the creek often occurring up to several days after a storm.
Ti.11 soils are consolidated, contain large percentages of silt or clay, and have
low percolation rates compared to the outwash soils. Only a small fraction of
- 17 -
CURRENT AND FUTURE CONDITIONS
WATER
the infiltrated precipitation reaches the groundwater; the rest moves laterally
through the thin surface soil, often re-emerging at the base of hillslopes.
This shallow, subsurface, lateral movement of flow is called interflow.
Interflow travels to the creek much faster than groundwater but slower than
surface runoff. Till soils may become saturated in moderate to large storms and
produce significant amounts of surface runoff. The peak runoff rate from till:
areas is therefore typically much higher than from outwash areas.
Wetland soils remain saturated throughout much of the year. Although the runoff
""from wetland areas is typically constant in the summer, during the wet season
they produce significant amounts of surface runoff.
Three types of cover were considered in analyzing the hydrology of the 5oos
Creek system: forest, grass/pasture, and impervious. Runoff from forested
_r areas produces the least amount of surface runoff. Forest cover is most
significant in till areas because it breaks up the structure of the till soils
.-and allows more infiltration to occur. Interception and evapotranspiration,
which influence -autumn, spring, and summer storms the most, is greater in
forested areas than in the other cover categories.
'Grass"ed areas produce more surface runoff, than forested areas. Because grass is
.shallow -rooted, it does not contribute to infiltration as forested cover does.
Grassed areas therefore saturate more quickly and produce more overland flow in
large storms than forested areas.
Impervious areas produce the most surface flow, because the infiltration rate in
impervious areas is zero.
The combination of forest cover and outwash soil produces the lowest peak flows,
with grass -covered outwash producing the next lowest, then forested till,
grassed till, and finally impervious cover. Peak flows from wetland soils are
variable depending on when the storm occurs. In winter when the wetland soils
are saturated, they produce high peaks similar to grassed till areas. In summer
the wetlands infiltrate precipitation and the runoff characteristics more
closely resemble forested outwash.
Receiving creeks, lakes, and wetlands also affect the runoff characteristics
from 'a given area. These features store flows and release them more slowly,
thus reducing the flow peak. The degree to which these flows are reduced
depends upon the roughness, slope, size, and shape of the channel. The most -
sensitive of these parameters is channel size. Thus wetlands and lakes are
typically more effective than a typical stream channel at reducing flow peaks.
Hydrology Under 1985 Land Use
Introduction: Flows from the various tributaries in the 5oos Creek system were
quantified using the HSPF model. It was desirable to examine the hydrologic
response of the basin under as many different storm and low -flow conditions as
possible. To do this, the longest suitable rainfall record available was input
to the HSPF model. This record was collected at the gage at Seattle -Tacoma
International Airport. The length of the record is 38 years, spanning October
M:
CURRENT AND FUTURE CONDITIONS
WATER
i-
1948 through September 1986. -The record contains several high -intensity storms,
as well as several drought years. The land use was held constant at 1985 levels
throughout the simulation (Figure 6).
Figure 8 shows the results of the simulation run (flows for other intermediate,
frequencies are listed in the Background Information and References section).
The HSPF model simulates flows at the outlet of each subbasin. Flows have been
listed in terms of probability, or flow frequency. For example, in Subcatchment
S16, the 100-year flow is 59 cubic feet per second (cfs). This means that a
flow of 59 cfs has a one percent probability of occurring in any one year. Flow
frequencies were computed using a Log -Pearson: analysis (Water Resources Council,
Bulletin 17a, 1977).
...General Trends: Flows in the more densely developed areas of the Soos Creek
asin are higher than those farther east in the Jenkins and Covington Creek
Basins. Areas with the highest flow rates relative to the area draining to them
are areas.in the western part of the basin where development is heaviest. These
areas include: the Meridian Valley Tributary (Subcatchment SB), upstream of
Lake Meridian (Subcatchment LH3), and Soosette Creek (Subcatchment ST1-ST5).
Natural features that presently attenuate high flows from urbanization include:
the wetlands along the main stem of Big Sons Creek (Subcatchments S16, S15, S13,
S11, S9, and S7), Lake Meridian (Subcatchment LM2), and Soos creek Wetland 50 at
the outlet of Subcatchments ST4 and ST5.
s Peak flows from the Jenkins and Covington Creek Basins are much lower than those
in the.Soos Basin, primarily due to the undeveloped state of the basin, the
.numerous lakes and wetlands, -and the large areas of highly infiltrative outwash
._ soil. Jenkins and Covington Creeks respond slowly after a storm event, with a
gradual rise and fall in flow typical of a groundwater -dominated basin.
Hydrology Under Buildout Conditions
Introduction: The effects of future land use on basin hydrology were examined
using the HSPF model. The future land use scenario that was assumed for analy-
sis was buildout conditions (Figure 7), defined as the densest use permitted
under existing or proposed land use plans and zoning. This analysis assumed
r that no human -made flow controls were present.
Under future 'conditions, flood peaks -with a recurrence interval of two years
(the 2--year flow) are predicted to increase up to 3.5 times, with an average
increase of 1.6 times over 1985 land use. Peak flows at the 100-year level have
an average increase of 1.5 times over 1985 (Figure 9). A particular flood stage
will recur more often, on average, but each event of a given frequency will
occupy less time. This corresponds with the notion of "flashy" urban streams.
'There are 1985 flow data for 56 of the 58 subcatchments. Of these, 28 are
u predicted to have future flows occurring more frequently than every 25 years
that equal or exceed the 500-year flow modeled under current conditions. In the
Little Soos drainage basin (Subcatchments LS4-LSI), the 500-year flows under
1985 land use are predicted to occur on average every other year.
"t
CURRENT AND FUTURE CONDITIONS
WATER
Flow Increases Due To Loss of Forest: Figure la shows future peak flows.
Generally, the subcatchments that change from forested land cover to urban uses
on till soils are predicted to have the greatest increases in peak flows. The
subcatchments in the upper Soos Creek Basin surrounding Lake Youngs
(Subcatchments S14, S12, LS4, and LS3), the area downstream of Shadow Lake in
Jenkins Basin (Subcatchments J5 and J4), and the area in the lower Covington
Basin (Subcatchment C8) are of this type. Peak flows in some of these areas
tripled despite the fact that land use densities are relatively low (one unit
per acre or less in most cases). These areas a'f-e therefore the most'sensitive
to increased peak flows caused by -development.
Flow Increases Due To Increased Impervious Area: Impervious surfaces are the
mostinfluential hydrologic parameter in determining how much flows will
increase from existing to future conditions. Increases in peak flows under 1985
land use in the following areas may be attributed to large increases in
impervious areas associated with 'urbanization: Lake Meridian Tributary
(Subcatchments LM3, and LMQ , Soosette Tributary (Subcatchments ST5, ST4, 5T3,
ST2, and ST1), South Fork Jenkins Creek (Subcatchments SF3, SF2, and SF1), and
Ravensdale Lake (Subcatchment C12).
System Effects of Increased Peak Flows: Although flows are expected to increase
dramatically in the locations described above, the system -wide effects are
not expected to be as severe due to the mitigating effects of natural 'features
in the basin. These features include extensive riparian wetlands, lakes with
large volumes, and infiltrative soils.
Increased flows will increase the magnitude and frequency of water surface
elevation in lakes and wetlands. Because the volumes of the lakes in the Soos
Creek Basin are large compared to the area draining to them, the fluctuations in
r. water elevation under future land use were found to be small, typically two feet
or less. Therefore, frequent flooding of lake -side structures should not be a
problem under future land use.
The effects of increased flows due to urbanization will be greater on wetlands.
Because -wetlands typically have smaller volumes than lakes, increased flows will
cause greater fluctuations of water depth there than in lakes. This fluctuation
can cause changes in plant species, and ultimately result in more open water
(see Plants and Animals section for a detailed discussion -of wetlands):
Other Hydrologic Effects of Increased Impervious Area: Although the NSPF model
displays particularly well the peak -flow increases that accompany urbanization,
other changes will occur as well. Most significant will be distruption in the
groundwater regime, particularly the loss to storm flow of water that used to
infiltrate and recharge groundwater reservoirs. In the Jenkins and Covington
Basins in particular, where streams, riparian wetlands, and shallow.groundwater
form a unifed system, disruption of recharge may have long-term consequences,
particularly the lowering of wetland water levels and the reduction of non -storm
stream flows.
CURRENT AND FUTURE CONDITIONS
WATER
'. C•CC��r.�-�CC�A��PCCGGPL �--.LC--�-t:-�-�-GSS--C=a����GCFS.'C�-G--�-GC-«G-«--x-G=
Area --Specific Effects
Upper Soos Creek: Increased flows from Subcatchments S14, S12, and S1O are
attenuated by wetlands located along the mainstem in Subcatchments S13 and S11r
Because the tributaries in these subcatchments flow through deep gullies,
flooding is not expected to be a problem in the future. Further, erosion is not
expected to be rapid because the channels are underlain by till.
Peak flows in the headwaters of'the Lake Meridian Tributary are buffered by -Lake
Meridian.. Although flows downstream of the Take (Subcatchment LMI) are
predicted to more than double, the magnitude of flow is still small compared to
the capacity of the channel to convey the flow. There have been reports of
-flooding downstream of the lake in Subcatchment LM1; however, this is a result
of an inadequate outlet structure on an onsite detention pond and is not due to
peak flows from upstream. Predicted flow increases in this tributary are
therefore not considered problematic.
Specific flow -related problems in the Upper Soos Basin are as follows (see
Figure 11 for locations).
Map
Reference Location
(Figure 11)
Description
A. Meridian Valley above Culverts under roads
132nd Ave. undersized.
B. Upper Soos Creek upstream of Channel through apartment
Petrovitsky Rd. complex undersized.
C. Meridian Valley at SE 240th St. Parking lot constructed within
drainage swale. Floods annually.
D. Soos-Creek at SE 256th St. Bridge height too low for future
and SE 148th St. flows. Predicted to flood on average
every 10 years under future land use.
Little Soos Creek: Increased flows in Little Soos Creek will exacerbate an
existing flooding problem at SE 264th St. (Figure 11). Increased flows are
expected to worsen erosion in the lower reaches of this tributary
(Subcatchment LS1) and increase sedimentation at the confluence with the
mainstem.
CURRENT AND FUTURE CONDITIONS - -
WATER
Map
Reference Location
(Figure 11)
E. Little Soos Creek at SE
264th St. and 164th Ave. SE
Description
Up to four houses flood annually:
two others will flood every two
years under future condition s
Jenkins. Creek: Flow increases.. in the south fork of Jenkins Creek
Tributary 0088)-are not expected to produce flooding problems despite the high -
density areas (three to seven units per acre) tributary to this reach. The
extensive outwash deposits and the riparian wetlands along the creek attenuate
peak. flows such that future flows increase by 50 percent over 1985 levels below
oa Subcatchment SFi. Instrm erosion in this area also is not expected to be a.
factor because of the low channel gradients. Similarly, high flows from
Subcatchments J10 and J8 are attenuated by the extensive wetland system along
the stream in Subcatchment J7 and therefore are not considered to be
problematic.
Two existing local flow -related problems are identified in the Jenkins Creek
Basin (Figure 11) and are expected -to worsen under future land use:
Map
Reference Location Description
(Figure 11)
F. Peter Grubb Rd, near Shadow Roadway flooding due to
z Lake high water levels in lake.
_. G. Witte Rd. at Lake Sedimentation from eroding
Wilderness Golf Club hillslope filling roadside ditch,
Covington Creek: Flow increases near Ravensdale Lake (Subcatchment C12) are
mitigated by wetlands downstream in Subcatchment C11. While the flows from
Ravensdale Lake are predicted to double, the magnitude of flow is small and is .
x therefore not expected to cause significant -flow -related problems.
flow increases downstream of Lake Sawyer (Subcatchment C8) are sufficient to
contribute to increased erosion in the ravine downstream in Subcatchment C2.
This is a significant system -wide problem because of existing erosion and the
contribution of sediment to the mainstem of Big Soos Creek.
Map
_. Reference Location Description
(Figure 11)
is
H. Lower Covington Erosion_ Sedimentation from eroding streambank
is settling in lower Big Soos Creek.
0
RECOMMENDED PLAN
AREA -SPECIFIC RECOMMENDATIONS
r
that seek to address localized impacts to water quality or fish habitat are
presented by subbasin. Land use and regulatory solutions, concentrated in the
eastern part of the basin to ensure adequate future protection of the high_
quality resource there and downstream, are also discussed by subbasin.
r
The second section of the Recommended Plan discusses conditions that occur
throughout the Soos Creek system and recommendations that address them.
Basinwide recommendations that have Countywide applicability also are in this
section. These basinwide recommendations apply throughout the Soos Creek system
unless superseded ---by area -specific requirements.. -
AREA -SPECIFIC RECOMMENDATIONS
UPPER SOOS BASIN: Big Soos Creek and Its Tributaries 'North of RM 4.6
Introduction
The Upper Soos Creek area is one in transition, with urban -related problems in
its west and north reaches and rural problems in the east. Big Soos Creek and
Its seven northern tributaries are low -gradient streams with many riparian
wetlands. Big Soos Creek flows through Soos Creek Park from about RM 7 to 13.
The northwestern portions of the upper Soos Creek Basin are developing rapidly
and most of the area is expected to develop to urban densities of one unit per
acre or more. Surface water problems in this area include flooding and high
peak flows, increased future peak flows and flooding, and aquatic habitat damage.
Recommendations (Figure 21)
Flooding: Flooding of apartments near SE 176th St. and County roads SE 256th
St. and 148th Ave. SF occurs. To reduce this flooding, the following projects
are recommended:
UPPER SODS CREEK CHANNEL AND CULVERT IMPROVEMENT (Project 5401a), a
conveyance enlargement and culvert improvement project to reduce roadway and
apartment flooding. Estimated cost*: $224,000.
° SE 256TH1148TH SE ROAD RAISING (Project 5417), raising of the SE 256th St.
bridge and the road elevation at-148th Ave..SE. Estimated cost: $230,000.
MERIDIAN VALLEY CHANNEL AND CULVERT IMPROVEMENT (Projects 542la15422), a
combination of channel stabilization and culvert enlargement on SE 240th St.
near the 132nd Ave. SE intersection. Estimated cost: $455,.000.
* All project costs are for initial implementation only, and do not include
ongoing operation and maintenance costs.
- 79 -
1. _ — r�''. - •�+r � � _.
Figure 21
UPPER SODS BASIN
RECOMMENDATIONS
-Boundary
Streams And Stream
-"'
Numbers
Aquatic Fiabita#
Improvement
Streambank Stabiliza#ion
DF SE4TRE
�. .
Channel Improvement
Culvert Enlargement
Debris Removal
Livestock Access
Limitations
Regional Retention
x
Detention Facility
=rtar
&
Revegetation
-Road Raising
•
Stream Improvement Study
xr._
Retain Low Densities in
Comprehensive Plan Rural
Areas (also see Figure 28)
2---Year Single Family
}
RID Standard
k AL
Retain Forest Cover
5417
Project Number
N
p 1 mile
i
�r
RECOMMENDED PLAN
AREA -SPECIFIC RECOMMENDATIONS
° CLARK LAKE TRIBUTARY HYDROLOGY STUDY (Project 5409), an engineering study of
Tributary 0091A from 132nd Ave. SE to the headwaters to evaluate alternatives
for control of flooding on this tributary. To be done in conjunction with
design of 542la15422 and investigation of downstream drainage complaints.
Estimated cost: $20,000.
r
Future Flows: Erosion, habitat damage, and more frequent flooding are -predicted
as peak flows increase more than two -fold if there is no mitigation. .Much of
these flow increases will result from the removal of forest growing on till
nails. Any future loss of the natural storage capacity of wetlands and
fioodplains will aggravate these problems. However; the damage from increased
flows should not be as significant where large lakes, such as Lake Meridian, can
store additional runoff.
_Proj-ects 5401a, 5417, 542la15422, 5409 (see above) will be sized to control
future flows. In addition to the basinwide recommendations (see Basinwide
Recommendations section), the following actions are recommended to reduce habi-
tat damage and these future flow increases:
° LAKE YOUNGS FOREST RETENTION (AS1). The approximately 830-acre Lake Youngs
Watershed should be retained in forested land cover. Because no acquisition
is possible at this time, King County may benefit from an option to purchase
at a later date or other long-term preservation agreement with the City of
Seattle. Implementing Document: Interlocal Agreement, King County Open
Space Plan, or Soos Creek Community Plan.
° UPPER SODS RURAL DENSITIES (AS2). Areas designated as rural -residential
In the 1985 King County Comprehensive Plan should be retained in rural den-
sities in the upper Soos Creek Basin from Big Soos Creek east toward the
Little Soos Basin (Subcatchments S7, S9, SID, S12, and 514). Implementing
Document: Soos Creek Community Plan.
UPPER SODS REDUCED ONSITE DETENTION STANDARDS (AS3). In the Lake Meridian
subcatchment (LM2), onsite RID facilities in conjunction with single-family
a, development (seven unitslacre or less) may be designed to a reduced 2-year
24-hour detention standard if the releases can be conveyed to the lake
without causing flooding or erosion. Implementing Document: King County
Surface Water Design Manual appendix.
Aquatic Habitat Dama2ee: Aquatic habitat has been damaged by channelization,
livestock trampling, devegetation, poor water quality, debris dumping, erosion
` and sedimentation, and removal of large organic debris (logs and stumps). The
following projects are recommended to address these problems:
° PROJECTS 5450, 5451, 5452, 5453, and 5459, to restore instream habitat
diversity. Estimated costs*: $165,000; $10,000; $10,000; $10,DD0; and $1,250
respectively.
* Aquatic habitat and water quality improvement project costs reflect
construction costs only.
- 81 -
RECOMMENDED PLAN
AREA -SPECIFIC RECOMMENDATIONS
° PROJECTS 5454, 5458, 5470, 5471, to limit horse and livestock access to
streams. Estimated costs: $200; $200; $1,500; and $12,200 respectively.
° PROJECTS 5466 and 5467, to revegetate streambanks. Estimated costs: $2,750
and $13,000 respectively.
° PROJECTS 5474, to remove debris from streams. Estimated cost: $1,400.
° PROJECTS 5460 and 5482, to restore natural channels and improve water
quality. Estimated costs: $86,500,and $178,000-`espectively.
Discussion
- The goals in the Upper Soos Creek Basin are to. reduce flooding of structures and
roads-, retain the integrity of stream channels, and protect the remaining
aquatic habitat. Key to these goals is the recommendation to retain rural den-
sities in the eastern half of the area (Subcatchments S7, S9, S1O, 512, and S14)
and to preserve the forest cover in the Lake Youngs watershed.
The main resource in the Upper Soos area is the extensive riparian wetland
system along the mainstem. This wetland, considered important system -wide,
currently provides excellent rearing habitat for salmonids, wildlife habitat,
and aesthetic benefits to users of Soos Creek Park. During 1989, the King
County Natural Resources and Parks Division completed five projects to remove
debris, provide stormwater detention, revegetate streambanks, and provide stream
viewing areas. These habitat -related projects in and near the park will improve
both the wetland habitat and the quality of water entering this wetland from the
east. One additional project, the raising or culverting of the SE 216th St. and
SE 224th St. roadbeds, was evaluated during basin plan preparation and found to
be ineffective in remedying local sedimentation of spawning gravels and reducing
saturation of trails.
Future peak flows entering the mainstem-of Soos from the eastern tributaries are
predicted to nearly double, even under the Recommended Plan. This increase in
flows is comparatively high. However, flooding in these tributaries'is expected
to be minimal since they flow through fairly confined channels with adequate
conveyance. Increased stream erosion from these channels and subsequent deposi-
tion in the mainstem wetland,•however, may pose local problems as development
progresses.
The high flows entering from the eastern tributaries are subsequently buffered
by the large storage capacity in the mainstem wetland system, resulting -in a
small (15 percent) increase in flows over 1985 land use at the wetland outlet.
These increases should not significantly expand floodplains nor harm aquatic
habitat in the wetland, although some wetland expansion is expected.
The projects and regulatory solutions proposed in the Upper Soos Creek area
reduce flooding frequency at three existing local flooding sites, protect
streamside wetlands along the mainstem of Big Soos, improve aquatic habitat, and
reduce new development -related problems.
- 82 -
RECOMMENDED PLAN
AREA -SPECIFIC RECOMMENDATIONS
Project 5401a will address a local flooding problem in the headwaters of Big Soos
Creek by increasing the channel and culvert capacity in the flooded area.
Project 5417 will raise the rotkd elevation of SE 256th St. above the 25-year
floodplain. This project will not appreciably affect flows or fioodplain
elevations in the creek.
Project 5421a/5422 proposes to replace the culvert crossing SE 240th-St. with a
larger capacity culvert and stablize the downstream channel. The project will
reduce flooding that currently occurs at a-2-year frequency to a 25-year fre-
quency. All -culverts will be replaced to WSDOF standardt--for fish passage.
Project 5409 proposes to study alternatives to reduce flooding downstream of
Clark Lake to SE 240th St. This project should be designed in conjunction with
Projects 5421a and 5422.
Implementation
Table 5 summarizes the Upper Soos Creek Basin recommendations, their costs, and
implementation priority. Implementation of recommendations within the
jurisdiction of other agencies and King County divisions will be negotiated with
these agencies. Cost estimates or schedules will be refined during these
negotiations. Recommendations to be implemented by the SWM Division are
scheduled according to their rank and the availability of SWM Program revenues
-for the Soos Creek area.
RECOMMENDED PLAN
- -
AREA -SPECIFIC
RECOMMENDATIONS
`
TABLE 5
UPPER SOOS IMPLEMENTATION
SUMMARY
Agency
Initial
ID
Involve-
Implemen-
Imple-
ment
Benefit
tation Cost
mentatioh
_ 1/
Description
2/
3/
4/
Period 51
A51
Lake Youngs Forest
OS
1
10,400
Year
2
AS2
Upper Soos Rural Dens:"
PCD._,..
1
0
ongoing
5450
Trib. 0072 Chnl.Reloc.
SWM
1
165,000
Year
3
.5451
RM 7 Hab.Improvement
NRP
1
10,000
Year
1
5452
RM 7.5 Hab.Improv.
NRP
1
10,000
Year
1
5453
RM 9.1 Hab.Improv.
NRP
1
10,000
Year
1
54.54
Equestrian Ac. Signs
SWM
1
200
Year
1
5458
Equestrian Ac. Signs
SWM
3
200
Year
1
5459
Trib.0091A Hab.Improv.
SWM
4
1,250
Year
4
5460
Trib.0091A Channel
SWM
4
86,500
Year
4
5466
Trib.0091A Revege.
SWM
5
2,750
Year
4
5467
Trib.0091A Revege.
SWM
5
13,000
Year
4
5470.
Trib.0094 Livestock Ac.
SWM
5
1,500
Year
4
5471
Trib.0095 Livestock Ac.
-SWM
5
12,200
Year
4
;. 5474
-T rib.0095A Hab.Improv.
5WM
6
1,400
Year
4
5401a-
Upper Soos Crk ConveyanceSWM
8
224,000
Year
5
5417. _
256th/148th Rd Raising
SWM/RDS
9
230,000
Year
5
AS3.
Upper Soos RID Stds.
BALD
10
0
Year
1
5409
Clark Lk. Trib. Study
SWM
11
20,000
Year
1
y` 5421a122
Meridian Yly Channel
SWM
'11
455,000
in progress
5482. .
RM 7.3 Channel Improv.
SWM
11
178,000
Year
5
BASINWIDE RECOMMENDATIONS (see Basinwide Recommendations section)
a
1/ Recommendation number from Recommended Plan.
21 PCD = Planning and Community Development Division
'BALD - Building and Land Development Division
NRP = Natural Resources and Parks Division
RDS = Roads Division
Wv SWM = Surface Water Management Division
3/ All project and non -project plan recommendations were ranked on a 1 to 12 scale
using multiple criteria with 1 as the highest rank. See Background Information
and References section for details.
4/ For projects, costs do not include operation and maintenance costs. For non-
__ project recommendations, costs represent added King County' administration costs
for the Soos Creek Basin Planning Area only; see Background Information and
References section for details. NRP projects were proposed in the 1990 budget,
but not funded.
5/ Yearly schedules are established for the first five years. After five years,
plan implementation should be reevaluated and implementation of remaining pro-
jects scheduled for specific years.
- 84 -
rr=ccccraccrcccccccssstsrsatssa.asrccrrcrcctcr-t:=acctrra�crrrr«rczrttr=sac-mc=
ALTERNATIVE SOLUTIONS AND IMPACTS
INTRODUCTION
r'
ALTERNATIVE SOLUTIONS AND IMPACTS: Alternative
Solutions, Significant ImpaEFs, and Mitigation
INTRODUCTION
The alternative solutions, impacts, and preferred alternatives are presented in
three sections. Alternative solutions for area -specific p.roblems in six regions
of the Soos Creek system are in the first section. The second"section
identifies and compares -alternative solutions to basinwide problems. Finally,
the generalized environmental impacts of these alternatives are discussed.
- AREA -SPECIFIC ALTERNATIVES
INTRODUCTION
The Soos Creek Basin Plan encompasses an area with a diverse range of geologic
terrains., aquatic environments, and land use activities. In the western part of
the Soos Creek system, rapid urban development has contributed to high flows and
consequent flooding, bank erosion, and aquatic habitat problems. In the eastern
pant of..the..sy.stem, which includes virtually all of the Jenkins and Covington
Creeks-Basins,.low levels of existing development and favorable terrain have
resulted in some of the highest quality fish habitat in King County.
.To address the. -specific concerns in these diverse areas, this section identifies
and compares alternative solutions to problems in six regions of the Soos Creek
system. These regions include (progressing from the headwaters downstream) the
Upper-Soos, Little Soos, Jenkins, Covington, Soosette, and Lower Soos Basins.
v
UPPER SODS BASIN: Big Soos Creek and Its Tributaries North of RM 4.6
Flooding
v. Issues and Alternatives
Apartment Flooding: Periodic flooding of apartments near 174th Ave. SE causes
property damage. To protect these apartments from future flow increases, the
following actions were considered:
° NO ACTION, allow periodic local flooding of apartments to continue.
° SOOS,CREEK WETLAND 1 REGIONAL DETENTION POND (Project 5401), a regional
detention pond on Tributary 0072 at RM 14.3. Estimated cost: $322,000
(Figure 32).
° UPPER SODS CREEK CHANNEL AND CULVERT IMPROVEMENT, (Project 5401a), a
conveyance enlargement and culvert improvement project in upper Tributary
0072. Estimated cost: $224,000.
I
Y,
Figure 32
r7T
UPPER SODS BASIN
ALTERNATIVES
413oundary
36
Streams And Stream
Numbers
Aquatic Habitat
A
j
I L
Improvement
X
f k
t -L
Q
Streambank Stabilization
OF SEALTru
I L k
Channel Improvement
�f t4.%
Culvert Enlargement
Debris Removal
�71
Livestock Access
Limitations
Regidnal Retention
Detention Facility
3
ad
ff-- .5
Revegetat ion
(7h
lav
Road Raising
0
Stream Iriprovement Study
Retain Low Densities in
Comprehensive Plan Rural
Areas (also see Figure 28)
5452
2—Year Single Family
RID Standard
-5451
Retain Forest Cover
ZA.(
5417
Project Number
N
A
1lllM—==3MM=
0 1 mile
ALTERNATIVE SOLUTIONS AND IMPACTS
AREA -SPECIFIC ALTERNATIVES
Road Flooding: Flooding of SE 256th St. and 148th Ave. SE exceeds King County
oads and Engineering Division standards, potentially creating a traffic safety
hazard. To provide 25-year flood protection under future lapd use conditions,
the following actions were considered:
° NO ACTION, allow periodic flooding of SE 256th and 148th Ave. SE to continuo.
° SE 256TH1148TH SE ROAD RAISING (Project 5417), raising of the SE 256th St.
-,bridge and the road elevation at 148th Ave. SE. Estimated cost: $230,000.
MIDDLE SODS WETLAND 30 REGIONAL DETENTION POND (Project 5417a), a regional
detention pond on Tributary 0072 at SE 148th Ave. to reduce flooding of.
SE 256th St. Estimated cost: $464,000
Shopping Center Flooding: Periodic flooding of the Meridian Valley Shopping
Center and SE 240th St. causes property damage and traffic safety problems.. To
protect the shopping center and road from unacceptable flooding under future
land use conditions, the following actions were considered:
° NO ACTION, allow periodic flooding of Meridian: Valley Shopping Center and
SE 240th St. to continue.
° MERIDIAN VALLEY DETENTION AND CULVERT REPLACEMENT (projects 542115422), a
regional detention pond, channel stabilization, and culvert enlargement on
SE 240th St. near the 132nd Ave. SE intersection. Estimated cost: $280,000.
° MERIDIAN VALLEY CHANNEL AND CULVERT IMPROVEMENT (Project 5421a15422), a
combination of channel stabilization and culvert enlargement on SE 240th St.
near the 132nd Ave. SE intersection. Estimated cost: $455,000.
° SOOS CREEK WETLAND 20 REGIONAL DETENTION POND (Project 5407), a regional
detention pond on 'tributary 0091B in a ff2-rated wetland to reduce flows and
roadway flooding. Estimated cost: $517,000.
° CLARK LAKE TRIBUTARY HYDROLOGY STUDY (Project 5409), an engineering study of
Tributary 0091A from 132nd Ave. SE to the headwaters to evaluate alternatives
for control of flooding on this tributary. To be done in conjunction with
design of 542la15422. Estimated cost: $20,000.
Comparison of Impacts: (See Generalized Impacts of Alternative Solutions
section for more detailed impacts.) The Upper Soos Conveyance Alternative
(5401a) would effectively reduce local apartment flooding by increasing storm -
water conveyance capacity during high flowsr The Upper Soot Detention
.. Alternative (Project 5401) would also be effective in reducing flooding.
However, this alternative could change the wetland's plant and animalspecies by
changing water levels and would not have the storage capacity to reduce flows'
much beyond the apartments.
Flooding of SE 256th St. would be effectively reduced by either raising of the
road (Project 541.7) or upstream detention (Project 5417a). However, detention
(Project 5417a) could impact park uses and aquatic habitat by creating more
sedimentation resulting in wetland and floodplain expansion.
ALTERNATIVE SOLUTIONS AND IMPACTS -
AREA -SPECIFIC ALTERNATIVES
The Meridian Valley Detention and Culvert Alternative (Project 5421122) would
not have sufficient capacity to adequately reduce flooding and downstream ero-
sion. This alternative would effectively reduce flooding of Meridian Valley
Shopping Center and SE 240th St. but must be implemented in combination with
downstream bank stabilization and the Clark Lake Study Alternative to reduce
downstream erosion and degradation fish habitat.
The Soos Creek Wetland 20 Detentio6 Alternative (Project 5407) would reduce peak
stream flows downstream to SE 240th St. but is on a tributary that contributes
y only a small part of the stream flows at the floodirg site. Thus this facility
would not be effective in reducing flooding, although it would reduce periodic
high flows for the upper 0.5 mile of Tributary 0091B.
The Clark -Lake Tributary study would be done in conjunction with the design for
.Projects 5421a15422. The study would identify sources of flooding problems and
evaluate solutions -to problems observed in the reach between SE 240th St. and
the Big Soos Creek confluence during the January 9, 1990 storm.
If the No -Action Alternative is selected for any of the three flooding problems,
periodic flooding of an apartment building, shopping center, and roads would
continue. As a result, the use of these facilities would be limited during
floods, and property damage and safety hazards would continue.
Preferred Alternatives: .The Soos Creek Wetland outlet channel improvements
Project 5401a is the preferred alternative to the apartment flooding at 174th
Ave. SE, because it would effectively reduce, flooding without creating wetland
impacts.
SE 256th St.1148th Ave. SE Road Raising (Project 5417) is the preferred
alternative for reducing flooding of SE 256th St. and 148th Ave. SE. This pro-
ject would reduce flooding and have little impact on surrounding wetlands,
floodplain elevations, or adjacent park uses.
Finally, the Meridian Valley Detention and Culvert Enlargement (Project 5421a/22)
and Clark Lake Tributary Hydrology Study (Project 5409) together are the'pre-
ferred alternative for reducing flooding of the Meridian Valley Shopping -Center
and SE 240th St. This alternative is preferred because it allows flooding and
i erosion problems throughout this reach to be evaluated together, resulting in
solutions that reduce flooding and flow -related erosion from the creek's head-
waters to its confluence with Big Soos Creek,
Future Flows
Introduction: Erosion, habitat damage, and more 'frequent flooding are predicted
as peak flows increase more, than two -fold in some areas. Much of these flow
increases will result from the removal of forest growing on till soils. Any
future loss of the natural storage capacity of wetlands and floodplains will
aggravate these problems. However, the damage from increased flows should not
be significant below large lakes such as Lake Meridian which store runoff and
release it slowly.
- 160 -
ALTERNATIVE SOLUTIONS AND IMPACTS
AREA -SPECIFIC ALTERNATIVES
In addition to the basinwide alternatives (see Basinwide Alternatives section),
the following actions are considered so that future flooding is reduced and
future flow levels are as close°,to today's flows as feasible:
° NO ACTION, areas would continue to develop at densities allowed by the King'
County Comprehensive Plan, Community Plan, and zoning, as amended in the '
future.
° CURRENT FLOODING PREFERRED ALTERNATIVES (Projects 5401a, 5409, 5417, and
5421a/22)_ The stream improvement projects considered as solutions to
current flooding problems will be designed to function under future land use
conditions.
LAKE YOUNGS FOREST RETENTION (AS1). The approximately 830 acre Lake Youngs
Watershed would be retained in forested land cover. Because no acquisition
As possible at this time, the County may benefit from an option to purchase
- at - a later date or other long-term preservation agreement with the City of
Seattle.
° UPPER-SOOSRURAL DENSITIES (AS2). Areas designated as rural -residential in
the 1965 King County Comprehensive Plan should be retained in rural densities
In the Upper Soos Creek Basin.
° UPPER SOOS ONSITE DETENTION STANDARDS (AS3). In the Lake Meridian
subcatchment (LM2), onsite RID facilities,in new developments with single-
family densities of sever: units/acre or less may be designed to a 2-year
detention standard if -the water can be conveyed to the lake without causing
flooding or erosion.
Comparison of Impacts: (See Generalized Impacts of Alternative Solutions
section for more detailed Impacts.) Because the Rural Density Alternative (AS2)
is consistent with the 1965 King County Comprehensive Plan, this alternative
would be effective if it prevented future plan amendments to allow higher
densities. This alternative (AS2) would be most effective if implemented in
combination with the basinwide clearing limits (BW3 and CW4) (see Basinwide
Alternatives section). This alternative would affect about 1,540 acres east of
Upper Soos Creek toward the Little Soos Basin.
Because of. Lake Meridian's large volume relative to the flows entering it, the
- basinwide onsite RID standards (BW2, see Basinwide Alternatives section) are
' unnecessarily restrictive compared to the area -specific standard (AS3).
Basinwide onsite RID standards also would increase the cost of private
development more than the area -specific standards. However, facilities should
not be designed to the 2-year standard if their releases would result in
flooding or erosion before discharge to the lake.
Although the Lake Youngs Forest Retention Alternative (A51) is feasible only for
the Lake Youngs Watershed where a large forested headwater area remains in
public ownership, it would effectively reduce future flows in a subbasin that is
very sensitive to deforestation -related flow increases.
ALTERNATIVE SOLUTIONS AND IMPACTS
AREA -SPECIFIC ALTERNATIVES
If the No -Action Alternative is selected, future peak 2--year flows would
increase an average of 66 percent over 1985 levels. As a result, flooding of an
apartment building, shopping center, and two roads; erosion; and aquatic habitat
damage would continue and likely tiorsen. '
Preferred Alternative: Because no alternative alone can effectively reduce
future flows enough to protect stream channels and habitat, and reduce flooding,
the Lake Youngs Forest Retention (AS1), Rural Densities (AS2); Current Flooding
Preferred Alternatives (Projects 540.1a, 5409, 5417, 5421al22), and Reduced
Onsite Detention Standards (AS3) Alternatives together afe the preferred alter-
native. Under the preferred alternative, average 2-year peak flows are pre-
dicted to be reduced by 74 percent of the predicted flows under the No -Action
Alternative.
Aquatic Habitat and Water Quality
Introduction: Aquatic habitat has been damaged by channelization, livestock
trampling, devegetation, poor water quality, debris dumping, erosion and
sedimentation, and removal of large organic debris. These observed problems are
predicted to continue or worsen due -to development -related increases in flow and
human activity. In the future, surface water quality could be degraded by
onsite septic systems sited too near reaches with adjacent highly infiltrative
soils and shallow groundwater aquifers.
In addition to the Basinwide Alternatives, the actions listed below were
considered to improve habitat damaged by past human activity and reduce future
habitat and water quality problems. Although the listed projects may have
alternative design features, these features cannot be evaluated here because
only minimal site data are available. As a result, the No -Action Alternative is
considered the only alternative to the projects. Any required evaluation of the
impacts of alternative design features will be conducted at the time of project
design and implementation.
° NO ACTION, Allow aquatic habitat damage from livestock trampling, loss of
forested streamside corridors, channel alterations, flows, and water quality
T degradation to remain.
° AQUATIC HABITAT IMPROVEMENT.
Current Flooding and Future Flow Preferred Alternatives (Projects 5401a,
5409, 5417, 5421a 22,. AS1, AS2, and AS3 , these preferred alternatives
are designed to reduce flows and thus reduce flow -related habitat damage.
The Density Preferred Alternatives (AS1 and AS2) also would reduce habitat
damage caused by increased human intrusion into and alteration of riparian
areas.
Projects 5450, 5451, 5452, 5453, and 5459, to restore instream habitat
diversity. Estimated costs: 165,000; 10,000; $10,000; $10,000; and
$1,250 respectively.
Projects_5.454, 5458, 5470, and 5471, to limit livestock access to streams.
Estimated Costs: $200; 200; 1,500; and $12,200 respectively.
199 -
L CZCZtC== === = == === == ===== === ...CCCC=CC=C=C_=__==_===== ====<<C=C=CCCCC=C=CCCCC.-.==G
ALTERNATIVE SOLUTIONS AND IMPACTS
AREA --SPECIFIC ALTERNATIVES
Projects 5466 and 5467, to revegetate streambanks. Estimated Costs: $2,750
and $13,000 respectively.
Projecl_5474, to remove debris from streams. Estimated Cost: $1,400.
Proiects 5460 and 5482, to restore natural channels and improve water
'quality. Estimated Costs: $86,500 and $178,000 respectively.'
Comparison of _Ympacts: (See Generalized Impacts of Alternative Solutidns
section for more, detailed impact`s.) Livestock Fencing Projects (5454, 54581
"- 5470, and 5471) would restore damaged streambanks and reduce the potential€or
fecal coliform contamination of the stream system, but would reduce available
grazing area compared to the No -Action Alternative. Projects 5450, 5451, 5452,
5453, and 5459 would improve instream habitat diversity and reduce fish
stranding in Soos Creek Park compared to the No -Action Alternative, but could
- result in temporary construction -related turbidity. Projects 5473 and 5474
would improve instream habitat diversity by removing debris from streams.
Projects 5460 and 5482 i4ould have temporary construction -related erosion
'Impacts,, --but would restore natural channels and improve water quality in the
term compared to the fro -Action Alternative. Projects 5466 and 5467 would
revegetate streambanks damaged by past human activity, thus reducing erosion and
providing shade and other benefits of vegetation compared to the No -Action
Alternative.
The Current flooding and Future Flow Preferred Alternatives '(Projects 5401a,
5409, 54179 542ial22, AS1, AS2, and A53) would be designed to reduce current and
future flows, and -thus reduce flow -related habitat damage compared to the
No -Action Alternative. The Density Preferred Alternatives (AS1 and A52) also
would reduce habitat damage caused by increased human intrusion into and
alteration of riparian areas.
If the No -Action Alternative is selected, identified aquatic habitat and water
quality problems would continue and likely worsen. Aquatic habitat would
continue to degrade due to increased flows, greater human alteration of
wetlands, stream channels,, and riparian corridors, reduced aesthetic value of
Soos Creek Park, and continued livestock -related damage. '
Preferred Alternative: Individually the aquatic habitat improvement projects
have only local benefits and impacts, but together they improve the overall
habitat diversity in this subbasin. As a result, all the aquatic habitat
improvement projects are part of the preferred alternative. Control of flows by
the Current flooding and Future Flow Preferred Alternatives (Projects 5401,
5409, 5417, 5421al22, AS1, AS2, and AS3) is preferred for reducing flow -related
habitat damage.
Basinwide Preferred Alternatives
Except where superseded by the Area -specific Preferred Alternatives, the
Basinwide Preferred Alternatives (see Basinwide Alternatives section) also would
apply in the Upper Soos Basin.
- 163 -
ALTERNATIVE SOLUTIONS AND IMPACTS - - -
AREA -SPECIFIC ALTERNATIVES
LITTLE SOOS BASIN: Little Soos Creek and Its Tributaries
Flooding
Introduction: Human alteration of the stream channel and construction in the
floodplain has caused almost annual flooding of four to six houses in the lower
reaches. To protect these houses and two additional houses from the future
100-year flow, the following projects were considered:
NO ACTION, Continued almost annual flooding'of four houses.
° LITTLE SODS CHANNEL AND CULVERT ENLARGEMENT (Project 5416), a channel and
culvert enlargement project at RM 0.6 and RM IJ. Estimated cost: $404,000
(Figure 33).
° LITTLE SODS REGIONAL DETENTION POND (Project 5416a), a regional detention
r
pond on Tributary 0092 at RM 1.6. Estimated cost: $250,000.
° LITTLE SODS HIGH -FLOW BYPASS (Project 5416b)., an approximately one -mile -long
pipeline to divert high flows to Big Soos Creek. Estimated cost:
$2,000,000•
HOUSE PURCHASE (Project 5416c), County purchase of the six houses in the
future floodplain. Estimated cost: $800,000.
Comparison of Impactsc (See Generalized Impacts of Alternative Solutions section
for more detailed impacts.-) The regional detention pond (Project 5416a) would
be ineffective. in reducing flooding due to site limitations, providing a
16 percent flow reduction only for future flows below the 2-year flow. The
high -flow bypass (Project 5416b) would be effective in reducing flows in Little
Soos Creek, but is costly, would transfer flow increases to Big Soos Greek, and
would require extensive right-of-way acquisition along the stream corridor,
disrupting several residences. Purchase of the houses (Project 5416c) would
effectively reduce the exposure of residents to flooding but may be difficult to
implement, is costly, and would not reduce erosion or improve habitat,in-this
channelized reach.
If the No -Action Alternative is selected, the current flooding problems and
resulting property damage in this reach would continue and likely worsen.
Preferred Alternative: The Little Soos Channel and Culvert Enlargement (Project
5416) is the preferred alternative because it would effectively reduce the flood
s. damage, would cause only localized disruption of land uses and habitat, and is
comparatively more cost-effective. Instream habitat and fish passage
restoration is also possible with'this alternative. Right--of-way costs would be
relatively high.
1 P l
Exhibit "E"
Reconnaissance Report No. 2
Soos Greek Basin
' Petro Vista Level 1 Downstream Analysis
RECONNAISSANCE REPORT NO. 2
SOOS CREEK BASIN
JANUARY 1986
Natural Resources and Parks Division
and Surface Water Management Division
King County, Washington
Kmg County Executive
Tim Hill
Ding County Counca
Audrey Gruver, District 1
Cynthia Sullivan, District ?
Bill 'Reams, District 3
Lois North, District 4
Ron Sims, District 5
Bruce Laing, District 6
Paul Barden, District 7
Bob Grieve, District 8
Gary Grant, District 4
Department of Public Works
Parrs, Planning and Resources
Don LaBelle, Director
Joe Nagel, Director
Surface Water Management Division Natural Resources and Parks Division
Joseph J. Simmler, Division Manager Russ Cahill, Division Manager
Jim Krasner, Assistant Division
Manager Bill Jolly, Acting Division Manager
Dave Clark, Manager, River S:
Water Derek Poon, Chief, Resources PlanninL- Section
Resource Section
Bill Eckel, Manager, Basin Planning Program
Larry Gibbons, Manager, Project
hianagement and Design Section
Contributing Staff
Contributing Staff
Doug Chin, Sr. Engineer
Ray Heller. Project Manager Team Leader
Randall Parsons; Sr. Engineer
Matthew Clark; Project Manager
Andy Levesque, Sr. Engineer
Robert R. Fuerstenberg, Biologist S, Team Leader
Bruce Barker, Engineer
Matthew J. Bruengo, Geologist
Arnv Stonkus, Engineer
Lee Benda, Geologist
Ray Steiger, Engineer
Derek Booth, Geologist
Pete RinFen, Engineer
Dvanne Sheldon, Wetlands Biologist
Cindy Baker, Earth Scientist
Di Johnson, Planning Support Technician
Robert Radek. Planning Support Technician
Randal Bays; Planning Support Technician
Fred Bentler; Planning Support Technician
Gaasulti z Staff
Mark Hudson, Planning Support Technician
Sharon Clausen, Planning Support Technician
" Don Spencer, Associate Geologist, Earth David Truax, Planning Support Technician
Consultants, Inc.
Brian Vanderbur- Planning Support Technician
John Bethel; Soil Scientist, Earth
Carolyn M. Byerly, Technical Writer
. Consultants; Inc.
Susanna Hornig, Technical Writer
Virginia Newman, Graphic Artki
Marcia McNulty, Typesetter
Mildred Miller, Typesetter
Jaki Reed, Typesetter
Lela Lira. Office Technician
Marty Cox. Office Technician
P: CR
. A
TABLE OF CONTENT'S
I. SUMMARY
1
II. INTRODUCTION
1
III. FINDINGS IN SOOS CREEK BASIN
2
A Overview
2
B. E€feels of Urbanization
3
C. Specific Problems
4
1. Bank failures
4
2. Channel erosion
4
3. Flooding and potential flooding
4
4. Stream habitat
4
IV. RECOMMENDATIONS 5
A_ Inform appropriate governmental agencies of 5
the reconnaissance findings
8. Reevaluate specific surface water management 5
policies
C. Prepare a comprehensive basin plan G
D. Construct the capital improvement projects 6
E. Maintain or enhance instream and riparian habitats 6
V. MAP 7
APPENDICES:
APPENDIX A: Estimated Costs A -I
APPENDIX B: 'Capital Improvement Project Ranking B-1
APPENDIX C: Detailed Findinzs and Recommendations C-1
L SUMMARY
The Soos Creek Basin is located north and east of the Green River in King County. While
the southern and eastern portions of the basin are rural, the remainder is a rapidly
expanding suburban community. This development pattern has not caused serious
environmental damage or flooding, however, due to highly pervious soils, an extensive
network of streams and wetlands that provide natural storage for stormwater runoff, and the
fact that development has only recently accelerated in this basin.
Although the overall severity of problems in the Soos Creels Basin was not great at the time
of reconnaissance, several sic., ificant problems were identified and should be addressed-
_ - These include bank failures, channel erosion, flooding in some locations, and poor stream
F
habitah
r , Recommendations to address these problems include efforts to 1) inform appropriate
' agencies of the reconnaissance findings, 2) reevaluate specific policy issues regarding the
management of surface water, 3) prepare a comprehensive basin plan, 4) construct the
capital improvement projects evaluated with citizen advisory committee criteria, and 5)
maintain or enhance habitat throughout the basin.
b INTRODUCTION: History and GoaLs of the Program
In 1935 the King County Council approved funding for the Planning Division (now called
the Natural Resources and Parks Division), in coordination with the Surface Water
Management Division, to conduct a reconnaissance of 29 major drainage basins located in
King County. The effort began with an initial investigation of three basins --Evans, Soon,
and Hylebos Creeks — in order to determine existing and potential surface water problems
and to recommend action to mitigate and prevent these problems. These initial
investigations used available data and new field observations to examine geology, hydrology,
and habitat conditions in each basin.
Findings from these three basins led the King County Council to adopt Resolution 6018 in
April 1936, calling for reconnaissance to be completed on the remaining 26 basins. The
' Basin Reconnaissance Program, which was subsequently established, is now an important
z element of surface water management- The goals of the program are to provide useful data
with regard to 1) critical problems needing immediate solutions, 2) basin characteristics for
a = use in the preparation of detailed basin management plans, and 3) capital costs associated
with the early resolution of drainage problems_
The reconnaissance reports are intended to provide an evaluation of present drainage
conditions in the County in order to transmit information to policymakers to aid them in
developing more detailed regulatory measures and specific capital improvement plans. They
are not intended to ascribe in any conclusive manner the causes of drainage or erosion
problems: instead, they are to be used as initial surveys from which choices for subsequent
detailed engineering and other professional environmental analyses may be made. Due to
the limited amount of time available for the field work in each basin; the reports must be
viewed as descriptive environmental narratives rather than as final engineering conclusions.
Recommendations contained in each report provide a description of potential mitigative
measures for each particular basin; these measures might provide maximum environmental
protection through capital project construction or development approval conditions. The
appropriate extent of such measures will be decided on. a case -by -east basis by County
officials responsible for reviewing applications for permit approvals and for choosing among
competing projects for public construction. Nothing in the reports is intended to substitute
Soos Creek Basin
(continued)
for a more thorough environmental and engineering analysis possible on a site -specific basis
for any proposal.
IM FINDINGS IN SOOS [[REEK BAMN
Reconnaissance in the Soos Creek Basin was conducted in November 1935 by Ray Heller,
resource planner, Randall Parsons, engineer, and Don Spencer and John Bethel, consulting
soil scientists. Their findings and recommendations are presented as follows.
A- Overview of Sows Creek Basin
Geographic and land use features. The Soos Creek Basin is located north and east of
the Green River in the eastern portion of the Soos Creek Plateau Community Planning
Area. The basin is situated east of the city of Kent, northeast of Auburn, and
southeast of Renton. The city of Seattle's Lake Youngs wratershed is included in the
Soos Creek Basin_
The south and east portions of the basin are rural in character, with the north and
west portions committed to a suburban development pattern that includes subdivisions
and scattered single-family homes. The 1985 King County Comprehensive Plan shows
areas east of Big Soos Creek (in the northern part of the basin) and south of Lake
Youngs with "rural development" designations that specify 1-5 dwelling units (DU) per
acre. The southern area to the cast of Soos Creek and north of the Green River is
designated "transitional." This interim designation will limit development to rural -
residential densities until such time as, ruraIlurban designations are made through
updated community plans.
- The King County Parks Department owns more than a five -mile stretch from Southeast
192nd Street to Lake Meridian, along Bio Soos Creek. These presently undeveloped
park lands are mostly wetlands and lie within the 100-year floodpiain.
Major geologic, hydraulic, and hydrologic features. The Soos Creek drainage area is a
tributary basin to the Green River basin_ The area is part of the Puget Sound
lowlands and is characterized by a glacial drift plain, covered by small ridges and
rounded hills that were formed by continental glaciation.
While the Soos Creek Basin is moderately developed, the degree and amount of
channel erosion, slope failures, and other forms of geologic and hvdraulic damage are
far less than might be expected. Artificial conveyances are also still functioning in this
basin as they were originally designed and intended.
These conditions may be explained by three main factors.. first, there is a very
effective natural retention and detention (RID) system provided by an extensive
network of 52 wetlands and numerous major and minor streams. Most of the wetlands
are located in the northern portion of the basin in the upland areas as well as
adjacent to streams_ Big Soo$ Creek originates in the northeast corner of the plateau
and flows southeast to the junction of little Soos and Jenkins Creeks; then curves west
at its confluence with Covington Creek. Bio, Soos Creek joins the Green River east of
Auburn near State Road (SR) 13 at 160th Avenue SE. These wetlands and streams
appear to be functioning, well as stormwater control facilities for the current levels of
development, as well as serving to prevent damage from surface water runoff.
Socs Creek Basin
(continued)
Second, the soils in the upland areas generally have a high infiltrative capacity,
' particularly in the southern portion of the basin. Stormwater is absorbed into the
ground at these locations before it can cause erosion or other damage.
A
Third, development in the basin has only just begun. Properly functioning wetlands
and streams have not yet been altered, nor have well -draining soils been covered by
impervious surfaces to any great extent Maintaining these properly functioning
drainage systems should be a goal in this basin and will be the focus of
recommendations made later in the report.
Habitat eharacteristres. The habitat of Silos Creels Basin is generally good and
supports large populations of both native and hatchery anadmmous fish The source
of the hatchery fish is a State facility near the mouth of Sows Creek. Cutthroat trout
reside in stream waters, and anadromous fish spawn and travel in many of the
F tributaries and the main stem of Big Soos,according to field observations and reports
from local residents at the time of reconnaissance. Habitat is being damaged or
threatened in some places by bank erosion and degraded water quality associated with
7 . land clearing, livestock feces, and wetland filling for development. One of the more
serious instances of habitat -threatening erosion ong hates at the parking lot of the
Seattle International Raceway (SIR), which is located on the plateau in the lower
portion of the basin. Drainage fmm the paved parking Iot is increasing erosion in
nearby tributaries and filling spawning gravels with sediment. , Appendix C of this
ge or potential damage. Further water quality report identifies sites of habitat dama
information related to habitat in the basin can be found in the Critical Stream
Inventory of Soos Creek, published by Metro.
B_ Effects of Urbanization
Low levels of development in most parts of the Soos Creek Basin, together with a
well -functioning natural drainage system, have kept serious erosion, sedimentation, and
habitat damage to a minimum until now. However, the present and projected rates of
development indicate that there could be increasing amounts of damage, as suggested
by the types of problems observed during reconnaissance. The expansion of
impervious surfaces in the basin is already beginning to accelerate the rates and
volumes of stormwater flowing into (and reducing the capacities of) both natural and
artificial channels. Impervious surfaces are also reducing the amount of highly pervious
soils available to absorb runoff. The predictable impacts are already_ in evidence:
erosion, mass -wasting, sedimentation, and degraded water quality and other habitat
destruction.
The following section provides a more detailed account of problems found during field
investigation.
G Specific Problems Identified
The study team ermined numerous sites along the main stem of Big Soos. Little
Soos, and West Soos Creeks; as well as 21 small drainages tributary to these main
stems. Several of the most significant problems found during reconnaissance are
described below.
n•crn
Soos Creek Basin
(continued)
L Bank failunc, On Tributary 0072A, river mile 30, for example, there exists a
major bank failure triggered by bank undercutting. The source of the problem
appears to be increased runoff from street construction. Unless flaws are
intercepted and redirected to storm sewers or other facilities, there will be
increased bank erosion and consequential deterioration of property and stream
habitat.
2. Channel Erosion. This includes both instream and bank erosion caused by large
volumes of runoff emerging from storm drains and washing away highly erodible
soils. This creates a new, deeply incised channel that enlarges over time. One
example of this problem occurs on Tributary 0072 near the SIR in the lower
part of the basin. Large expanses of pavement at this location have contributed
to high volume flows and channel erosion.
3.' Flooding and potential flooding^ In numerous locations, development has
increased the amount of runoff entering existing drainage facilities or otherwise
impeded the ability of natural systems to carry the amount of runoff. When
drainage systems fail to function as they were intended, flooding can occur.
Increased development without concurrent increases in drainage facilities adds to
the possibility that serious flooding will occur. On Tributary 0092, river mile 1 20,
for example (collection point. if), the Little Soos -has been contained and
_ manicured as it passes through a developed plat. Such alteration to a natural
drainage channel reduces the stream's capacity in places. The result has been the
regular semi-annual flooding of some . homes Further development could
aggravate these kinds of flooding problems.
4_ Poor stream habitat due to:
a. Lack of overhead canopy and streamside vegctation. Overhead canopy
stabilizes water temperature, while streamside vegetation protects banks from
erosion.
b. Contamination by livestock feces. In areas of the basin where livestock have
' extensive access to streams, water quality has become degraded by animal
feces, These cause harmful nutrients to be added to the water which can
threaten fish survival
c. Erosion. Streambank and channel erosion, already descrihed above, is caused
in. part by livestock access. On Tributary 0073, river miles 3.604.70, for
example; there exists poor stream habitat because livestock have trampled
and denuded banks of vegetation; this has led to the sedimentation of
spawning areas and caused turbidity.
IV. RECOhDAENDATLONS FOR ACITON
The follow-ina recommendations Are based on findings of the field team and reflect the
original goals of the Basin Reconnaissance Program, as outlined in the introduction of this
report.
A. Inform appropriate governmental agencies of the detailed findings from the
reconnaissance of this basin. Project representatives should meet with staff from King
u.cl-n .f
Soos Creels Basin
(continued)
County Roads Division, Surface Water Management Division, Building and Land
Development, and other interested agencies to transmit relevant information.
B. Reevaluate spodfic policy issues regarding surface water management. These may ,r
include the need to:
L Improve enforcement of wetlands regulations to maintain these areas in their
natural states. This will insure their continued function as surface water quality
and quantity controllers, as well as -preserve their habitat value. If regulation
proves ineffective, the County should secure easements or consider other means
to preserve wetland areas.
3 2_ Require the' establishment of undisturbed buffers and setbacis adjacent to natural
drainap swales. Variations in stream morphology and geology indicate the need
for stream corridor guidelines that take these into consideration. Improve
enforcement of "no clearing" covenants in these sensitive areas or seek County
easements or actual ownership. Fencing along streams in livestock areas would
help water quality and reduce erosion and sedimentation.
3. Investigate and promote the infiltration of surface water where feasible and
economical to reduce increased runoff from developed areas. Also, encourage the
use of grass swules and open ditch conveyance systems to improve infiltration and
water quality enhancement capacity. Areas of high filtration are identified on
final display maps (for the Basin Reconnaissance Program) in the offices of
Surface Water Management, Building and Land Development, and Basin Planning_
i t 4. Require the tightlining of storm-draiaage outfalls down steep or sensitive
slopes using state-of-the-art facilities} including high density polyethylene pipe with
1
energy dissipation at the outfall.
S. Reevaluate stormwater rate and volume release regulations for new developments_
Current- regulations may be inadequate and result in unacceptable downstream
erosion that causes property damage and loss of habitat.
6. Increase current maintenance levels for.King County surface water RID and
conveyance facilities. Due to the lack of funding, maintenance of existing,
facilities is sometimes insufficient and results in facility dysfunction and failure.
These will only be aggravated by additional upstream development.
Soos Creek Basin
(continued)
C. Prepare a comprehensive basin plan to consider, at a minimums the need to:
L Enhanct aad utW= the extensive existing wetlands as regional storm -detention
facWties without jeopardizing habitat values. Prepare a schedule for the
anticipated need for these hydrologic enhancements as they relate to projected
development in the basin and impact the wetland ecology.
Z rmmine existing storm -detention and conveyance facilities to determine v6hether
their control orifices are .properly sized to optimize the detention site and achieve
the ma)dmum benefit to the downstream systems.
I Establish floodplains in Iow-lying areas of night gradient for existing and
developed runoff conditions, i.e., adjacent tQ wetlands, particularly for wetlands
proposed as regional detention sites where inundation of adjacent properties may
be significant-
4- Identify stream reaches critical to the maintenance of anadromous and trout
populations.
S. Review geologic findings from this study in order to identify areas of particular
soils' sensitivity and develop special analysis criteria for new developments.
D. Construct the capital improvement projects according to the CTP priority selection
criteria. These projects, identified in Appendix B of this report, include projects to:
1 Calibrate and retrofit existing detention -control structures and to improve existing
conveyance systems.
2 Stabilize channels and slopes-
3- Provide regional detention facilities, including the utilization of wetlands, where
biological assessment has determined that the natural habitat values will not be
* significantly altered.
E. Maintain or enhance the instream and riparian habitats..
1. Maintain wetlands and buffer areas around them_ These provide both valuable
wildlife habitat and natural stormwaicr storage that helps to maintain year-round
baseflows in the stream.
2- Adopt a stream -corridor policy in the Soos Creek Community Plan to protect the
stream corridor from damaging types of land uses in adjacent areas.
3. Encourage the Washington State Department of Fisheries to allow use of the
natural stream system for salmon spawning_ Maintain a natural run of all the
indigenous anadromous species.
4. Proiubit filling in the 100--year floodplain_ The County should establish
regulations to prevent the loss of floodplains in order to maintain their natural
y storage for floodwaters and guard against degradation of important fish and
wildlife habitat.
P•Cf R F,
�93Ha
r ar N G •„�
- 1
_ `, � ;,f,r� SaOS CR1=SIC BASIN
r
Fusin Boundary
} - MM or ••••••
Collection Point Boundary
$ Collection Point
`i -� �� f �L •`�. Stream
!4 Nt •T � r
w •5 \\
��.i �. � • ••• > T2 w,d, � € 0072 Tributary Number r fi
s� rr • sL
E ua IT '
*5401 Proposed Project
>=
ti R f IL C
/ 111i.
♦.i
IT _ j J/
ia•r Q! CN
ate` -fer � �� u _�_ ,_ aT Ta lfapM YaRcT
- � ♦�`
+ T ♦ 418 ` OF S PATT LE WATER SHE
zo-
j..��..L.J _ t t� �• E v .
IT •• a _.__i,s 5.-. ♦ <I
se nt S- • • C
u Mr nti ��311 _ V
N • M
€f� •
� ^y41! '-�-�`^',��1�+ [[�� >c •+ •f '•''•I••••• 'jeer P
'bra � . trm' � • •r .•}µ •��- • •• '•
5412 s
:
M IT
Big Soft
is
'��., •� -" \ ..._J � i J � i x �; �� wrJj O 1 � • _-`- Y <' of
t 4 - it R stp
, Ta si lB
• O
i �' + T F r' •: r :u srr n�
SZ
kk
5417
D • �`T�
or
Oil
07
-�.l.�S..J' • j • • it M,r IT • • ��,
`€ 51G F € • 1� Laa• E •• r 4-1 � :v7 " a �- ae' rr n
AI � a� —�t G Nedra" 3 £ • �'
I ^s • • ix ; E a • • •� � r
_ s •`Q �.••� •" • • • i • • : GMio3[=r+
,a�, �ll Big Sans ` .I • '*
Fi
�1e SODS CREEK BASIN,t
w j •. *�*�f Basin Boundary 7
- Meri�art
OCT ; a...a• Collection Point Boundary
T ' � . �, ••�' � • � a'� ,� R 8 Collection Point
�.. • r bl 541 o
o "` •'�� Stream
••• • 0472 Tributary Number
• • • : v *5401 Proposed Project
TO •5402
•--3
#.
ale
1 +�sr p • sE 1q • • IT
t � � � v *� � }' I � •� � ••. • • ! 7 1 fill
i _ rrt ar-eli IT • '
l 00 e1 ••• 9 E3° sr= rr
IF
7 � € is � • cart:... • • t•�
sE m IT r ^ i • -. • • � 3 -• CnvlFglon
: • r sR �-
' •
Y_s K 1H LT � ••�_ +� �•�•• K •� -ram
zi
4- r
Aii-
rR a
sT � • � f � ,=
,,.
y • • i
u sT
A sT a • I
L
tiro=' I10( � _
c i1i i =j • I t] i
• 'i i i • r
' • 1 ! •
d IFS )r, FT ••r• � , _� t � Ls� iT w
ij
r ar• i'F
tE4 �,ss� �' k -:
1y,sL�r �sRyyrr�l
Lt sE n� ra a • f r >• �i •• 1 `�
.j
.541
.�
1 I O i e
O f � Heights
G EN RlVL1L Fc ��-
"' y tI MH [TY VOLLEGE �sr
EAST
_ _ GREfN � - • F v � ' �_�_ �—
+ RIVER
y6 �
- ; * x a• L; O f� i
rr . ■+.,,4 .r.,.T...�S
i' =r rt
F+ LT
M
APIT-NUIX A
ESTIMATED COSTS: PROPOSUD CAPITAL IMPROVEMENT PROJE-CI'S
SOOS CREEK BASIN
* Indicates project was idenlitfed by the
Surlace Water Management Olvlslon prior
to reconnaissance.
NOTE: -All protects are located on map included
In this report.
Project
Number
.5401 *
5402 *
Collect.
Point
20
9
5403"
_5404* 17
Wullands 4410
Proiect UeScrintion
Constnict low berm (approx. 2') and
proportional discharge -control weir
nt outlet to wetland. ('Phis project
i5 independentty justifinble.) Welland
rating is #2. Biologient nssessment is
needed to assure this project does not
decrease hatbital values.
Cxcavale and berm to constnict regional
facility at lower end of wetland.
Provide proportional weir discharge.
Wetland rating is #1. Biological
assessment is needed to assure this
project does not decrease habitat values.
Could not locate or verify.
Construct a proportional control weir
at SL 224th St. bridge. (Project should
Oe justified by a Future basin
ptan.) Wetland rating is #2. Biological
assessment is needed to nssurc this
project does not decrease habitat values.
Estimated Costs
Problem Addressed and Comments
Mitigates increased upstream peak . 4153,000
flows zind runoff volumes. (likely to be much
less due to land
acquisition cost)
Mitigates increascd upstream peak
flows and nlnoff. This location serves
Trib. 0073 and 0076. (Good location)
Address in basin plan.
Mitigntes increased upstream peak flows
and runoff. (First site that could
address flows south of Pclrovitsky.)
P:SCUAPA A-1
$194,000
(dependent on land
costs)
(Eliminate for now.)
$250,000
Project
(:ollect.
Numt+cr
Point
5405°
19
.5400! 12
Wetland 5444
5407 15
Welland 5420
540,8*
13
Proicct Descrinlion
Constnict l,crm and proportional control
weir in Boulevard I.nne Park. (Project
should be justified by a basin
plan.) Wetlands rating is #1
Diologienl assessment is needed to
.tssurc this project does not decrease
habitat values.
Construct outlet -control structure
at existing culvert passing flow
under SU 250th St. (Project would
be independently justifiable.) Wetland
rating is #2. Uioloi-icnl n."msment is
needed to assure This Project does not
decrease Itnhilnt values.
C:onstnict a berm and proportional
discharge weir at outlet of existing
wetland. (Project should he justi-
fii;d by n hasin plan.) Wetland
ruing is #2. Biological nsscssment
is needed to nssure this project docs
not decrease habitat vaiues.
Raise Ilse SE 2401h St. roadway
approximately 2' and constrict a new
bridge with proportionnl control weir.
(Project should be juslified by n basin
plain.) Wetland rating is #2.
Biological nmessment is needed to
assure this project does not decrease
11.111itcit values.
Problem Addressed
Mitigates increased upstream peak
flows and nmoff.
Mitigates increased upstream peak
flows and runoff. May provide
extra detention to assist in
allevinting capacity problems far
downstrenm.
Mitigates Incrcnsed upstream peak
flows and ninoff.
Mitigates increased upstream peak
flows and ninoff. (Good location.)
P:S(,B.APA A-2
Estimated Costs
and Comments
$98,000
$ 17,800
$228,000
$70,000
Project Collect.
astimated Costs
Number Point
Project Deseri Lion
Problem Addressed
and Comments
5409*
13
Construct berm and proportional control
Mitigates increased upstream peak
$221,000
Wetland 5433
weir nt outlet to Clark Like. (Project
flows and runoff volumes. May
(depending on land
could be independently justified.)
providc extra detention to alleviate
costs)
Wetland rating is # I. Biological
capacity problem downstream.
nssemment is needed to assure this pro-
ject. does not decrease habitat values.
5410*
8
Construct ccrutril manhole at outlet
Provides continued detention for
$28,000
Wetland 5488
of existing pond. Dead storage should
mobile home park plus small amount
be maintained for aesthetics. (Project
of additional area.
semis of very limited vniuc.) Wctland
rating is #2.
5411*
J9
Small wetland located near top of
No project proposed. Maintain
(Eliminate for now.)
Wetland 5476
subbLtsin; maintain condition as is,
wetland in its existing state,
Wetland .rating is #2. Biological
assessment m needed to assure this
projet clots not decrease habitat values.
5412*
lG
Construct berm and proportional control
Mitigates increascd upstream peak flows
$246,500
Wetland 5480
weir at outlet to wetland. (Project
and runoff.
(dependent on land
should be justiCied by future basin
costs)
plan.) Wetland rating is #2. Biological
nssessmcnt is nccdcd to nsysurc this
project does not decrease habitat values.
5413*
3
Co berm and proportional control
Mitigates increased upstreamn peak
$193,600
Wetland 5477
weir at outlet to wetland adjacent to
flows and runoff. (May not lie as
(dependent on land
SIt 113. (Project should be justified by
desirable Lis Projects 5419 and 5420.)
costs)
future basin plan.) Wetland rating
is #2. Biological assessment is needed
to a."urc this project does not decrease
habilat VnIucs.
1'.Sr,B.A l'A A-3
Project
Ntamber
54 t4
Collect.
Point
2
5415 1
5416 11
5417 1:1
541.4 1.1
5419
5420
10
Proiect Descrinlion
Construct berm and excavate to
provide additional detention volume.
Construct a control monhote. (Project
is independently justifial,ie.)
Construct tightline system in
existing stream channel. (Project
i4 independently justirable.)
(,onstnact new latndscaped berms adjacent
to existing privately Owned and main-
tained stream channel to increase
capacity and prevent neighborhood
flooding. (Project is independently
jlist irable.)
Raise 148th Ave. SC roadway approx.
1.5' and construct proportional control
weir at SL 256th bridge. (Project is
independently jumifahle.)
Construct control weir at 1Tridge on
SE bake Youngs Wary. (Project should
lie justified by future basin plan.
C;onsiruct proportional weir tat existing
bridge. (Project should be justified
by rulure hasin plan,)
I 1 Divert excess flows from Little: Soon
into .tbandoned horrow pit for inrillrat-
lian. (Project should Ile justified by
fetturo haasin plain.)
Problem Addremed
Mitigntc incrcnned upstream peak flows
and runoff. Reconstruct discharge from
SE 320fh St. to stable outlet. (Justifiable
immediately due to impacts on state fish
hatchery,)
Prevents further road embankment and steep
cut -bank railures. (Justified immediately
duc to impacts on state fish hatchery.)
Prevent neighborhood flooding, which
jeopardizes 3-4 homes by containing stream
as it passes through plat. (Justifiable
immediately as situation will only worsen
with upstream development.)
Eliminate seasonal flooding of roadway
and mitigate increased upstream peak
rlows and runoff. (Justifiable immediately
slue to flooding of roadway.)
Mitigate increased upstream peak flows
and runoff.
Mitigate increased upstream peak flows
and runoff volumes. (Site appears,more
desirahlc than 5413 due, to ease of
atce"s.)
Mitigate increased upstream peak flows
and runorf volumes. (This is a highly
de5irablc n1ternative due to groundwater
recharge and quaalily control.)
11:SC B.Al1A A-4
Cstirnnted Costs
and Comments
$169,000
$156,000
$223,000
$88,700
$138,000
(dependent on land
use costs)
$ 88,500
APPENDIX B
CAPITAL IWROVEMENT PROJECT RANKING
SOOS CREEK BASIN
Prior to the Soos Creek watershed field reconnaissance, 13 projects had been identified and
rated using the CIP selection criteria developed by the Surface Water Management (SWM)
Division and the Natural Resources and Parks Division. Following the reconnaissance, 20
projects remain proposed for this area.. They include the 7 new, previously unidentified and
unrated projects plus the initial 13 projects.
A .
. The prcviou*, SWM capital improvements project list for the Soos Creels Basin had an
estimated cost of S3,450,000, while the Tevised list decreases to an estimated cost of
S2,62?,000. This 24 fo reduction in estimated capital costs is due mainly to downward revised
cost figures for acquiring or securing easements over wetlands.
The following table summarizes the scores and costs for the CIPs proposed for the Hylebos
Creels Basin. The 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: "GOINO-GO," could be answered affirmatively. The projects
can now be considered for merging into the "live" CIP list. Any project scoring over 100
points should be considered for incorporation into the six -year CIP plans
RANK PROJECT NO. SCORE COST
1 5415 135 S 156,000
2 5417 127 223,000
3 5407' 113 228,000
4 5414 105 169,000
5 5409" 100 221,000
6 5416 98 .68,400
7 5402" 95 194,000
3 5401 * 59 153,000
9 5406 * 33 17.300
TOTAL S1,43%000
* Indicates project was identified by SWM prior to the reconnaisance.
APPENDIX C
DETAl1.13,13 FINDINGS AND RECOMMENDATIONS
SOUS CREEK BASIN
All items fisted here are located on final display maps In
the offices of Surface Water Management, building and Land
Development, and Casin Planning.
'Drib. Collect.
Existing
Anticipated
;m River Mile Point
C:alegq Profs. Prof. Conditions and Problems
Conditions and Problems
Recommendations
0072 1
IIydrology Sec Item 6.
Main Stem will be strained to
New developments in upland area
ItM 2.84
accommodate increased volume
should Investigate Infiltration of
of runoff from developing
runoff as much, as possible. Direct
areas upstream. Hank erosion
discharge -to stream, after tightlining
(causing increased siltation
down sensitive slopes, is ltndesirnble.
and habitat destruction) and
"fast choice" Alternative.
slope failures (lending to
property damage) will result.
0072 1,3,10,
Habitat I labitnt of upper stream
More filling of wetlands.
Prohibit filling within IOD-yr.
RM .00 13,17,
good from buffer of exicn-
Sediment from adjacent devel-
floodplain or in wetlands. Work with
I8,19,
sivc wetlands and mninten-
opment will fill portions of
landowners to fcnccg alongside stream
20
ance by County Parks Dept,
wetlands and stream cliannel
to keep farm animals out.
Problems on 562 acres of
due to low gradients. More
wetlands include illegal
debris, pollution, and flood -
filling, livestock -related
ing will result from additions
bank erosion, debris in
development.
strezim. 'There is a greater
degree of development
adjacent to stretim, Main
stem provides important
rearinb habitat for
saimonid speei".
:SCUAPC: C •I
gravel bars. Terraccs
suggest occasional flows 2"
above current level.
P:SC13.A?(' C-2
Trih. •l t ollcel.
Uyisting 1
'ell) River Mile Point
f'atcroiy
11ron,_ ProL_ Conditions and Prowenis
G 0072 1
Geology
Main stem of Socs Creek is
RM 2.50
25' wick with well -developed
gravel bars. Terraces
suggest occasionni flows 2'
above current level.
7 0072 1
Geology
In vicinity of private foot
RM 2.00
bridge, medium to large
bank failures occur in silt/
clay -rich colluvium.
Causative mechanisms Include
undercutting and reduced
shear strcxngth owing to
abundant springs and seepage
8 0072 1
Private landowner has
ItM 2.60
placed riprap for 150' on
left tank.
9 0072
RM 2.( 5
0 0072
RM 2.RA-
5.85
1 Geology
3 Mydroloey 5413
.10" diamctcr CMP with
erosion in recessional
sands.
See Itom 6.
Anticipated
Conditions and Problems Recommendations
None. None.
Continued medium to large
failures into creek.
Trill and riprap will shift
stream onto opposite bank,
resulting in increased bank
erosion.
Continued mnintcnance.
Main stream will be increas-
ingly strninvd to handle
higher volume of runoff' from
developing areas. Bank
erosion anticipated, causing
litibitnt degradalion, slope
failures, and property damage.
None.
Restrict filling And riprap in
natural meander of floodpiain. If
property in danger, consider pro-
tective measures along strenmbank
such as riprap.
None.
New developments in upland area
should investigate infiltation of
runoff as much as possible. Direct-
ing discharge to stream after
tightlining down sensitive slopes
is undesirable "last choice" alter-
n ttl ive.
Tri1). & Collect.
Existing
Anticipated
cen River Mi1c Point
C atego Iron. Proi. Conditions and Problems
Conditions and Problems
Recommendations
I 0072 3
Geology West of confluence of
Creek blockage and threat to
Recessional sand deposits in sections
RM 4.20
Jenkins and Soos Creeks,
property near edge of bank.
2, 3, 10, 11, 14, 15, 16, 21, and 22
200' of sloughing in
of T 21 N, R 5 E are highly sensitive
r( tces.5ionnl sands and
to erosion. Identify discharge
gravels in 40'-high bank.
sources and cvtiluate adequacy and
Cause appears to he overbank
suitability of collection and convey-
discharce.
ance facilities. Require compliance
if none exists.
? 0072 3 habitat
RM 4.20
4
007?
RM 5.80
0072
RM 5.85
3 Geology
lt) IIydrology 5419
Stream liahitat appears to
he in good condition on
this siveper portion of the
stream. Riffles common,
with some pools. Stream.
side vegctntion and over-
hcad canopy both abundant.
Near bridge, stream flows
through wooded wetland.
Slight degree of develop-
ment has not caused sig-
nificant problems. South
portion of Wetland 6430
and undesignated wetland
at this collection point
provide RID for locnl and
upstream tributary flows.
Sonic; loenlixed hank over-
topping in portions of
main reach, but innundation
probably limited to adjac-
ent agrictlitunil land.
P:8(-.13.AP(', C-4
None, None.
Increased future flows could
overtop existing berm struc-
tures and flood adjacent
agricultural lands.
Area planned to develop only
moderately; significant prob-
lems will probably result
from upstream areas tribu-
tary to this point rather
than from flows generated
by runoff.
Development detention for
tributaries upstream.
A basin plan should examine
feasibility of directing flows from
Trib. 0092 at collection point 11
into proposed RID site at gravel
pit cast of 156th Pl. Sa. This
could provide infiltration, deten-
tion, and overflow discharge directly
to collection point 10.
'('rit)..0
C:ollccl.
Existing
Anticipated
Icm
itiver Mile
Point Oltegoa Prop. l'roj.
Conditions and Problems
Conditions and Problems
Recommendations
15
0072
13 C;cology
At 2561h crossing, wetlands
Overflow between SC 148th -and
Perform cost -benefit Analysis for
ItM 7.20
and slow flow chameterize
Si. 25001.
grade raise and improved drainage,
soils.
0072
I3 Geology
AI 244th (2401h) overland
None.
None.
RM 7.95
out -of -hank flow is common;
flooding.
7
0072
13 Hydrology 540
Wetlands provide RID for
Rooding of roadways will
Increase height of roadway embank -
Main Munn
5408
areas upstream and iribu-
become more common and
ments to prevent continued flooding.
RM 7.20-7.4
tary to reach. I48th Ave.
greater in extent as upland
Monitor wetlands for illegal filling
RM 7.95
SC roadway crossing wetlands
areas develop.
and grading.
in area is overtopped during
high flows due to a slight
elevation of roadway. Some
localized bank overtopping
in nonwellind portions of
main reach, tiut innundntion
limited to adjacent agri-
cultural land.
8
0072
17 Geology
Minor flooding in wetland
Increased flooding activity
Develop detention for upstream areas.
12M 9.45
areas with degradation of
Is likely with upstream
portions of SC 2241h.
development.
9
.0072
17 hydrology 5404
No significant problems in '
No upland problems nntici-
Monitor areas adjacent to wetland
RM 9.55
upland due to low level
prated as area is planned to
for illegal filling and take enforce-
dt-mlopment. Sr- 224th St.
develop very little more.
ment action as needed for restor-
road embankment is only
Any developments in areas
ation,
approx. 2' above wetland;
tribulary to this subbasin
May tie overtopped. Periodic
will exneerbate flooding of
overtopping and innundation
SE. 224th St.
of base, delcriorating road-
way where '1'rib. 0095 passes
under SU 2241h.
Trib. St Collect.
Existing
Anticipmed
lent River Mile: Point
Cite of I'ron. Proi. Conditions and Problems
Conditions and Problems
Recommendntions
0072 20
Ilydrology 5401 factors exphtinirig lack of
Recent installed snnitnry
Protect and enhance wetland. A
RM 14.25
problems in this area:
sewers make it likely that
high -density multi -family development
1) this uppermost subarea
area will tlpproach its
may be proposed adjacent to wetinnd
has no other tributary
anticipated density soon.
due to increasing development pres-
areas; 2) development is
Wetland will continue to
sures in .area.
moderate and many homes are
provide adequate buffer for
situ.ited on largo scvcrn!-
downstream system, provided
acre parcels; 3) an exten-
it is not degraded, by illegal
sivc wetland (#5401) nets
filling or clearing. Channel
as effective ntitural RID
upstream of wetland is likely
site, as evidenced at
to experience some capacity
collection point.
problems; these should be
addressed by. new developments
as they occur, possibly with
County coordinating a coopera-
tive funding of conveyance
improvements.
'.4 0072A 1
Habitat There are several severe
More development at collet-
- Repair erosion of RID pond at
RM 2.40
bank cuts, as well as debris
lion point 2 and at Green
upper end of tributary.
in strum. Ilabitat for
River Community College will
- Remove debris from stream.
NO is poor.
increase flows. Incrdnsed
flows will result in more
bank erosion, sediment, and
lom of habitat.
?5 0072A 1
GCOIc y Drain pipe undercuts to
Highlights potential for
CvRlunte source and establish
RM .2.5
Corm erosional chute.
continued or increased
alternate means of conveyance.
Natural springs have down-
erosion in loose colltrvium
cut 8' into soils
Trite, & Collect. Existing
cm River Mile Point Category Prop. Prof. Conditions and Problems
} 0072 18 (;c:ology Soon. headwatcrs flow slowly
RM 10.50 through smooth pasturctand.
[ (}072 1:3 IiydraloAy 5418 Wetland 5409 provides RID
RM 10.78 for areas tributary to
0072
RM 12.20
19 Hydrology 5405
reach. Sonic localized hank
overtopping in main reach
south of 204th Way, but
flooding currently limited
to ndjaceni agricultural:
land.
Wetland 5402 provides
natural RID to downstream
system, sllthough its func-
tions have been severely
degraded by illegal filling
south of and adjacent to
Petrovitsky Rd. and cast
of SE 182nd St. Some
capacity problems exist
at undercrossing of I'etro-
vitsky I2d.
I':SCI3.�1i'C C-G
Anticipated
Conditions and Problems Recommendations
None. None.
Continued dcvcopment may
cause some localized enpacity
problems in upland tributary
areas. flooding south of
SE 204th Way likely to become
more scvcre until upstream
rcgionnl detention sites
development.
Wetlands will continue to be
threatened by illegal filling
until effective enforcement
methods are developed.
Capncily problems should be
addre&-5ed by downstream anal-
ysis for new developments.
County should coordinate
conveyance improvements.
Monitor areas adjacent to wcdand
for illegal filling and lake enforce-
ment action as needed for restora-
tion.
Legal actions pending against illegal
filling; seek to restore wetland to
original state. Possible opportunity
to create multi -use facility in
existing King County Boulevard Lake
Park if need identified in future
basin plan.
......... .a
'frill. S' C:ollcc:t.
Existinb
Anticipated
ern Itiver Mile Point
Calegory
Prop. Prof_ Conditions and Problems
Conditions and Problems
Recommendations
? 0072C I
T labitat
Small, class 5 stream; poor
Erosion and downstream
Establish nonerosive stormwater
RM .10
fish habitat due to small
sedimentation inevitable if
rclense rates and volumes for
sire. Stremnside vegetation
development occurs.
future: development.
and overhead canopy in good
condition.
1 00721) 1
habitat
Scvcrc erosion, tank tail-
There will be more movement
Establish onsile control for SIR
RM .1{)
ure:s, slicks, and sediment
of large amounts of earth.
stormwater.
exist. ']'here are: ironfixing
bacterin from debris. Out -
fall from SIR puking. lot
flows into this tributary.
0073 I
I labitnt
I inbitat in good condition.
Muddy writers on rainy day show
- Rctnin natural stream corridor.
RM .30-.90
Nice pools and riffles,
crosionnl problems upstream
- Enforce erosion control require.
some debris duns but no
from collection point 5,
ments for new development.
fish blockages. Stream is
fairly high, muddy and
silty. Overhead trees
abundant, as is streamsidc
vegetation.
S 0073 I
Geology
I00- to 200-yr.-old debris
Unstable for construction.
Monitor during permit rcvie;w process.
RM .35
flow with recognizable fan
Risky.
morphology emerges from
narrow draw. May have been
triggered by logging before
turn of century.
1 0073 1
Geology
Silt exposed in slope
Continued bank recession,
Evaluate total system flows and,
RM RM .90
failure induced by
degrading of spawning encilronment. if prudent, develop alternatives
undercutting.
to instrenm discharge of runoff
.from developments.
Trib. &, Collect.
II-ximing
Anticipated
em River Mile: faint
C: ilegory Prop. Proj. Conditions and Problems
Conditions and Problems
Recommendations
0072A I
Geology Bunk failures or deltaic
Increased erosion of banks
Intercept source flows in street
RM .30
deposits (ancient lake)
and deterioration of habitat.
areas and direct to storm sewers
triggered by undercutting;
or sultablc facilities.
response to incrcnsccl flows
from streets above.
J 0072A 2
Hydrology 5414 Detention facility for
if not corrected, problem
Construct detention facility here
RM 2.10
Rainier Ridge single-family
will deeply incise swale bunk
and direct runoff from SC 312th
plat appeared to be
find transport an unacceptable
St. to this location. Annlysis and
'functioning, although one
volume or material to stream
design of facility should calibrate
section of berm had eroded
below. Incrcased runoff from
existing detention facilities and
severely and needs repair
area soon to be developed
construct retrofitting control
find .armor. Pipe directing
will nggravate slope failures
features 10 allow all facilities in
roadside runoff from
obsctved. Rench is of par-
the subbasin to work as a complete
north side of SC 3201h has
licular concern due to adverse
system.
railed, and runoff has
impacts on state fish hatchery
cut ditch through vege.
immediately downstream.
Cation to east, causing
significant slope C it=
on right bank of tributary.
It 0072B i
Ilabitat Culvert under.railrond is
Inercascd stream downcutting
Place strict onsite controls on any
RM .10
a fish blockngc. Small
and resulting bnnk erosion,
future development tributary to this
cpheme:ral stream undergoing
sidecutling, and sedimenta-
drainage, since no area exists for
Some bank erosion duc to
lion downstrcnrn will occur.
regional R/1D.
increased peak flows.
9 0072B 1
Geology Silt/clay lithology exposed
None.
None.
RM .75
in bank.
I':,5C:1.3.Al'C (:-8
'1'rib. & Collect. Existinc Anticipatcd
Ica River Mile Point C vlegol-� Prop. Proi. Conditions and Problems Conditions and Problems Rocommendations
t 0073
7 hydrology
Undetermined source produc.
ixcalized capacity problems
RM 2.15-
ing substantial suspended
will become more evident as
3.50
load or silt in iribulary.
arv<t develops.
Strcfim udeclunteiy accommo-
dating increased runoff
from upstream development.
2 0073
7 Cicofogy
Stream crossing with runoff
Slight flooding. .
RM 2.55
of 5-10 cfs. Evidence of
short-duralion flooding.
3 007.3
7 Geology
Evidcnee for sideeutting
Widening and undercutting of
ISM 2.�190
G" above existing flows.
bnnka in response to added
flows.
4 0073
7 Geology
On till soils, 00'-wide
None. Provides good index
RM 2.95
flood plains IS nbove
for evaluation of system.
existing flows with
evidence for additionnl
IS deptlt.
'5 0073
9 Ilydrology 5402
Extensive existing Wetlnnd
1''illing may occur in nren
RM 3.15_
5450 is currently providing
along north border of
3.65
R/I) buffering the flow
wetland to increase amount
bcrore it passes into
of potential commercial real
channel through King County
estate. Subarea development
Housing Authority develop-
may cause localized capacity
ment.
problems in lower reaches.
G 0073
7 Geology
1n housing development,
C:onlinved erosion around
RM 3.14
erosion around culvert
structure.
enininee 2' nhovo existing
Clowy.
NSC13.I1PC C-11
No regional facility proposed for
this tributary due to lack of obvious
location, but Wsin plan may justify
one.
Maintain distance from 25-yr. flood -
plain using 3' above existing flows
as minimum guideline.
Notre.
None.
Monitor wetland for filling, take
action to obtain restoration if
this occurs. Enforce wetland
protection regulations.
Provide some armoring as bank protec-
tion (riprap).
Trill. S., toticct.
Existing
Anticipated
'will River Mik Point
C Aego1y Prop. Prol. C'ondition5 and Problems
Conditions and Problems
Recommendations
1 0073 1
Geology Silt exposed in
Continited bank rcceision,
Evaluate total system flows and,
RM .91
slope failure induced by
degradation of spawning
if prudent, develop alternatives
undercutting,
environment..
to instrenm discharge of runoff from
developments.
0 0073 1 Oc:ology
RM 1.00
7 0073 S 1lydroiogy
R 0073 S Geology
RM 1.60
9 0073 S Habitat
RM 1.60
10 0073 7 GCO1oty
RM 21.5
Litter and debris Mocks
stream channel.
Accelerated l7ank erosion
of nnain channel due.to
increased runoff upstream.
Trib. 007313 experiencing
serious instability near
confluence with main stem
due to development. (See
geologic appendix)
Confluence with tributnry;
erosional cuts suggest
recent flood raised stream
3' above existing flows.
Ilnbitnt in good condition.
Silt in suspension; live-
stock have access to stream.
Gentle (20%) side slopes in
pastureland. No evidence
of erosion, but flooding
reported.
I':tiC:13.lA 1' C C-10
PcHodic.breakout could
trigger flooding.
As wren above Trib. 0073
develops, erosion of swine
that conveys it wilt experi-
ence incrensing cnpncily
problems. Increase erosion
will occur ns stream attempts
to seek new equilibrium
capacity.
None.
s
Dank erosion will occur from
presence of livestock.
Slight increase in high flows
proportional to dcv0opcmnt
upstream.
Clean out and restore to natural
condition.
Future developments above Trib. 0073B
should use infiltrative capacity of
soils in the area as feasible to
reduce runoff. Developments ndjacent
to main stream channel should provide
adequate sctbecks from slopes to
prevent slope failure.
None.
-.Plant some trees in floodpinin.
corridor section.
- Put in some drop structures
to create pools.
None.
Trib. S' Collect.
Exisling
Anticip.tted
lem River Mile Point
Cnlugo I'rop. Proi.
C:ondinons amd Problems
Conditions and Problems
Recommendations
? 0074 1,4
IIydirology S4IS
Mosby undeveloped; high
future development offers
Construct proposed tightlinc project
RM .30-.50
percentace of open fields
opportunity to construct
to prevent failure of road
and Pastures. Bunk erosion
regional detention fneility,
embankment and transportation of
nlong west side of SE 312th
as undevetopcd nrea consists
material to sensitive main creek
Way lhreatens integrity
of sevenil large, contiguous
rcaehes.
of roadway.
parcels. Mink undercutting
will accelerate, causing failure
of roadway along 1000' of
SE: 312111 Way if only normal
detention requirements met.
Increased runoff from subOnsin
now developing will aggravate
slope failures and adversely
impact stale fish hatchery
. .
downstream.
;3 0074 1
1labitnt
[lnbitat downstream of SE
increased Ctows may cause
- Clean out debris.
RM .50
312th Way. Culvert is
scour and Dank erosion,
- Provide R/D as needed at top
improved from RM .50 but
of ravine.
only marginally. Lots of
debris in stream,
�4 0074 4
Ilabitnt
Ilillside and road sliding
Dank erosion, sedimentation
Armor stream bank and
RM .60
into strcnm at USGS stream
and road failure exist. This
reinforce road,
gauge at RM .10. 1101tnt
will be a big problem with
poor for fish clue to debris,
increased flows in future.
road, and erosion problems.
C-13
'I'rih. <<
(:cslEuct.
L'xixting
cm River Mile
Point
Calcgot
Prop. Conditions and Prohlcros
0073
7
Geology
Pent overlies till in
RM 3.55
wetland area.
t 0073
9
I habitat
Tnstrcam habitat is poor
RM 3.60-
due to Kick of overhead
4.70
canopy and stronmbank
vegetation in some areas.
Livestock have access to
stream; banks have been
eroded in some areas.
0073
g
Geology
Stream occupies swate in
RM 4.4
rolling terrace. No
erosional stress.
t} 0071
12
hydrology
5406 No signiCicant problems.
RM 4.75
007313 5 ITabilat Poor Cish habitnt. Small
RM .10,30 stream with bank erosion
and associated pitsturc
with livestock.
C- I2
Anticipated
Conditions and Problems Recommendations
None. None.
More flooding with increased
streambed and bank erosion
will occur.
None
- Establish more restrictive controls
on volumes and rates of release for
developments.
- Work with landowner to provide
fencing and natural vegetative
buffer along stream.
None.
Area planned for only slight Future basin plan should consider
ndditionnl development. No Wetlnnd 5444 for detention facility
problems anticipated. to Assist in alleviating downstream
capacity problems.
Increased bank erosion will T�stabllsh nonerosive stormwater
occur. release rates and volumes for
future developments.
Trib. -&, (:011cel.
ic:ni River Mile; Paint
�) 0091 1
RM 1.10
0 001)1A
RM .17-
?.4
i1 0041A.
RM .20
near
Existing
Cale^o Prop, Pros. Conditions and Problems
IIydrology .1410 t..hkc Meridian area nee
13 Hydrology 5401)
entirely developed with
single-family residences.
Lake acts as subregional
receiving body is effec-
livciy buffering runoff
to downstream reaches.
Some potential for flooding
of mobile home park down-
stream of lake due to
pox.5ible limited capacity
in pipe discharging; from
onsite pond.
Development is causing in-
creaxed capacity problems
and resulting increased
volume of runoff, scecler-
ting erosion of stream
channel in subdivisions
near golf course.
13 Iiahitat Altered portion of stream
due to road construction.
All riffles with rew, or no
pools. Alder shades stream
well.
il.SCU AN' C:115
Anticipated
Conditions and Problems - Recommendations
Area tributary to lake is Basin plan should consider
nearly completely developed, modification of Lake Meridian outlet
so little change is antici- to provide considerably more deten-
pated for system. Area south- tion with very minimal alteration
cast of lake has yet to fully of lake levels. This could substan-
dcvelop and potential exists tlally reduce future capacity
for localized conveyance problems immediately downstream.
capacity problems that should
be addressed by downstream
analysis for new developments.
Capacity problems will
increase ns upstream areas
arc developed.
Future problems only likely
to be scouring of smaller
rock during pork flows, due
to import of rock
Constrict berm and control structure
at outlet to Clark Lake to possibly
"detain" runoff and help reduce
flow downstream. If a high -density
multi -family project is propscd
near lake, as is likely, there
would be opportunity to develop
berm and control measures.
Address capacity problems at Clark
Lake by channel nrmoring or
upsizing pipe.
rlacemcnt of some larger rocks to
create pools and eddies.
il.SCU AN' C:115
Anticipated
Conditions and Problems - Recommendations
Area tributary to lake is Basin plan should consider
nearly completely developed, modification of Lake Meridian outlet
so little change is antici- to provide considerably more deten-
pated for system. Area south- tion with very minimal alteration
cast of lake has yet to fully of lake levels. This could substan-
dcvelop and potential exists tlally reduce future capacity
for localized conveyance problems immediately downstream.
capacity problems that should
be addressed by downstream
analysis for new developments.
Capacity problems will
increase ns upstream areas
arc developed.
Future problems only likely
to be scouring of smaller
rock during pork flows, due
to import of rock
Constrict berm and control structure
at outlet to Clark Lake to possibly
"detain" runoff and help reduce
flow downstream. If a high -density
multi -family project is propscd
near lake, as is likely, there
would be opportunity to develop
berm and control measures.
Address capacity problems at Clark
Lake by channel nrmoring or
upsizing pipe.
rlacemcnt of some larger rocks to
create pools and eddies.
... ......� _.. a'..-- .� :' :.t n I ..�:i M. ......d _ a �, .-fin ....la u - • --. .a i �
'I'rib. &
(:ollccl.
Uxisting
Anticipated
cm
River Mile
Point
Catcvry Prop._Proj. Conditions and Problems
Conditions and Problems
Recommendations
i
0075
6
Iiydrology Due to relatively slight
No problems anticipated as
None.
ItM .33-
degree of devclopmont,
aroa is planncd to develop
1.40
there do not appear to be
only slightly.
any significant problems
nt this Limo.
6
0081
9
Ilahiml No major problems other
None.
- Maintain stream corridor and
RM .It)
than lack or overhead canopy
buffer.
from loss of trees, vegeta-
. Encourage owner to fence stream
tion.
from animals.
7
0081
9
Geology Culvert 2.5' X 2.5' passes
Inermsed flows will have
Identify hydrocarbon source and
RM .02
under road. Srridcscent
minor increise in soil
test to eval unto -poll Man ls.
hydrocarbon sheon noted on
erosion.
Would be beneficial to isolate
surface. Some minor side-
livestock from sidebank areas and
bank scour noted.
establish vegetation on banks for
erosion control and filtration.
8
0081
9
IIabitat Stream has been ditched
Bank erosion will occur.
- Revegetnte streamsides.
RM .62
through pastum. Dirt
- Encourage owner to fence off stream
banks exposed with few or
from livestock.
no trees to shade stream.
11:S(:i3 AIT C-14
r_..w r—
r
r ..
1 r
x r r i i — .-r r-, r e 1 i - J
• r
.• r r
l'rih. -R, C;ollcct.
L'xis[ing
Anticipaled
Icm River Milc Point
Category Pry[ Proi. Conditions [Ind Problems
Condjlions and Problems
Rccommondntions
i7 0{)72 it
I lydrology 5416 Little Soon Creek tributary
As development continues,
No apparent suitable sites for
ISM .35-1,69
has been contained and mnni-
existing capacity problems
regional detention facilities to help
cured as it plisses through
will he furthcr aggravated by
reduce flow entering problem reaches.
plats. This has reduced
increased volume of runoff,
Address increased runoff volumes from
cop.,acity of strc-am in kcy
which previously was able to
new developments with infiltration
.are w, where t-:sullant
enter groundwater system
systems where feasible. Channel
channel overtopping causes
directly.
capacity enhancement projects (such ns
flooding of sonic: homes semi-
Projtm 5416) should be constructed
yearly.
to prevent further property damage.
Basin pinn should address potentiat
of detaining ri noff from upstream
tributary area to allow for increased
flows.
S 0092 ll Il,�hiln[
IZM .65
,e) 0092 1 ! I Icahihat
RM 1,60
{) 009? 14
RM 1.70
I 0092 14
RM 1.70-
3.65
Instrenm habitat is good.
Stream corridor mostly in
good condition. Manicured
lawns nun down to stream in
places.
Some debris found in stream
Ilabitat generally good.
Geology Meandering segment of
I..ittle Soo.; possible
colluvial creep in adjacent
sidebank areas.
Hydrology Little current development.
No significant problems
other Ilan some localized
hank overtopping in portions
of main reach. Innundation
will likely he limited to
adjacent ngriculiuml hand,
1':S('B.Al'C: C-17
Increased flows will cause
flooding and erosion.
Bank erosion, flooding, and
sedimentution likely to occur
Potentially unstable blanks
would affect construction.
Establish undisturbed stream
buffers.
- Stricter control on RID release
rates and volumes should be
established.
- Maintain natural buffer along most
of channel'.
If construction -were considered,
recommend evaluation of soils and
stability of sites.
As siren develops, channel Future developments should
capacity problems will becomC utilize infiltrative capacity of
more evident and increased soils to redt+ce increased runoff
erosion will oec^eur as stream volumes. Provide adcquntc flooding
,mumps to seek new cqui- protection for future runoff con-
Iihrium capacity. ditions.
Trib. &
C;ollcel.
Existing
Anticipated
em
River Mile
Point C atego
Prot. Prooi._ Conditions, ind Problems
Conditions and Problems
Recommendations
2
0091A
13 Ilabitat
Stream has been ditched and
More bank erosion and
Stabilize bank and shade stream by
RM .30
most streamside vegetation
sedimentation of channel
planting native vegetation.
removed through golf course.
expected.
Some bank erosion occurring.
Very little overhead vege-
tntion alongside stream.
3
0091A
11 1labitnt
Good streamside vegetative
There will be additional loss
- Enhance use of Clark Lake as RID
RM 1.20-
cover except through
of native vegetation along-
facility to reduce peak flows.
2.20
shopping center. Qverltcnd
side stream. More flooding
- Further restrict stormwater
canopy varies by property,
and erosion will occur.
rate and volume realcase rates.
3
0091B
15 1lydrology
.5407 Moderate amount of current
Localized capacity problems
Protect and possibly enhance wetlnnd
RM .62
development. Wetland 5240
may occur in upland tributary
as upper area _develops.
provides R/D, protecting
as areas develop. Wetland,
downstream channel from
if preserved, will continue
increased volume of runoff
to provide R/D for increased
as nrea develops. No Sig-
flow generated by new develop-
nifirmt problems in area.
ments.
:5
0092
3 Geology
Little Soos Creek near north
None.
None.
RM .10
margin of Covington Chnnnel.
No reported or observed flow
or erosion problems.
4
0092
3 Geology
Dcbris and bank erosion
Incroased bank erosion is
Reduce storm flows by use of stricter
RM .30
found.
expected.
stormwater controls, new RID facili-
ties, and fencing of stream.
increased flows.
l':SC:l3.Al'C: C-I 6
Trib. <<
Collect.
Existing
Anticipated
I=
River Mile
Point
C,'1c9orY
Prop. Prot._ Conditions and Problems
Conditions and Problems
Recommendations
(}
0073
1G
Habitat
Iran -fixing bacteria and
None.
None.
RM 4.65
associated odor present.
Sotimc; unknown. Lake Yottngs
release raatc is mininlurn
2 cf.
1
0093
14
habitat
Very small tributary with
Erosion and flooding from
Reduce storm flows by use of stricter
RM .00•.87
undefined channel in places.
future development likely.
stormwater controls, new R/D
1101itiat value for fish Is
facilities, and fencing of stream.
low.
;?
0093
14
Geolo;y
Poorly defined sirearn
None.
None.
RM 0.35
channel with no evidence
of erosion.
;3
0094
13
C;cology
Minor sidebanlc crosion
Slight cnlnrgcmcnt of
Ucnl armoring/riprnp applied by
RM 0130
ticlow convergence of two
erosional features. '
owners would reduce impacts.
culvert/creeks,
;4
0094
I3
1laabitnt
Streamside vegetation has
'nerc is a possibility of
- Provide stormwater control
RM .0.30
been removed by logging.
bank erosion due to increased
- Establish stream corridor buffer.
flows from development.
- Improve stormwater control.
;$
0094
13
I
Im ortnnt: This is a snlmon
More bank erosion will occur.
- Encoutage property owners to renc:e
RM 1.00
spttwning streaam. Some bank
stream.
erosion probably due to live-
- Provide stream corridor buffer.
stock.
- Improve stormwater control.
0094
13
Ilsabitat
11'11cre is riverine wetland
None,
Maintain• wetlands and stream corridor
RM i.50
just cast or 156th Ave SE.
in natural state.
I':S{'B.APC: C-19
Trih..5�
Collect.
Existing
Anticipated
turn
River Mite
Point C atc gory Pron. Prof.
Conditions and Problems
('onditions and Problems
Recommendations
'2
f 091)
14 Geology
Potentrti for flooding in
Possible flooding (minor),
Consider upstream detention.
RM 2.fi0
low areas; very low side.
slopes.
'3
0092
14
Some debris fotind.
Dank erosion and scdimcnta-
- Establish stricter control on
RM 2.1W
tion likely.
R/D release rates and voltumcs.
- Maintain natural buffer along most
of channel.
'4
0092
1Geology
Ovcrbnnk flows.
Possible flooding (minor).
Consider upstream detention.
RM 3.35
'S
0092
16 11allitat
Lots of send in bedlond.
More sedimentation likely,
- Establish stricter control on
RM :1.40
Streamside buffer generally
as well as bunk erosion and
R/D release rates and volumes.
good.
flooding,
- Maintain natural buffer along most
of channel.. -
76
0092
16 Gcology
Resident reports trees down
Some continued erosion.
Some clean -out of trees and
RM 3.40
in strcnm and sidebank
limited armoring of banks would be
erosion evident.
beneficial.
77
0092
16 I lydroloj y 5412
Little current development.
No problems anticipated
Consider Wetland 5480 for a
RM 3.65.
some localized bank over-
as very little additional
detention site, in a future basin
4.75
topping in portions of train
development is planned for
plan, in order to alleviate down-
rvach but innundntion is
tilts area.
stream capacity problems.
probnbly limited to adjacent
agricultural land.
78
0092
16 1labitat
Stream ditched. Little
Bank erosion and flooding of
- Work with land owner to fence off
RM 4.00-
sircamside vegetation and
now "improved" pasture will
stream.
4.40
no overhead canopy. Sonic
Occur.
- Plant native vegetation buffer.
livestock -related erosion
and runoff.
79
0092
16 Gcclog-y
Orange: iron precipitate
Sonic localized oxygen
Nntural deposition as iron is
RM 4.05
noted in strcambed near
depiction of fish habitat.
exchnnged for oxygen.
outlet to Loke Youngs.
I':SCi3.AI'C
C-i8
-
ip
Trib. S'
Collect.
Existing
Anticipated
em River Mile
Poinl
Calenoty
Prop. Proi. Conditions and Problems
C;onditionn and Problems
Recommendations
r 0095
17
1lahitat
Small, ephemehtl stream
None.
Encourage property owner to fence
RM .35-.185
flowing through pasture.
stream.
Livestock causing bank
erosion.
i f)O SA
IK
Habitat
Ditched .iron; lots of
Continued filling may
Maintain stream corridor. Enforce
RM
debris.
occur in flood plain.
grading and filling ordinance.
0095A
Is
Ilabit;It
Debris exists in salmon
This will have minimal effect
Maintain stream corridor in
RM .65
spawning area.
on habitat.
natural condition.
001}7 18 Geology Stream flowing Through Continuing ndjtistment will
RM .35 development shows minor bed occur until system cstnblishes
and bunk erosion ns stream n mature, developed water-
equilibmtes to new channel. course.
0097
RM .35
13 habitat
Debris and fill in wetland.
'.SCUAIC C-20
Morc filling may occur.
The key word is "equilibrates."
Disturbance of the natural system
has initiated or Induced rendjustmant
in the bed as a functlon of new
gradients, ranterlals, and othcr
hydraulic factors. In time, the
stream will establish Itself in
another "naturnt" equilibrium,
assuming no new variables such as
added flows or alteration of channel
geometry are introduced.
Enforce grading and filling ordinance.
Exhibit T"
FEMA Floodplain Map
;I
C -
Petro Vista Level t Downstream Analysis
determine it Il,:,od insurance is available, cantata an insurance agent or
A the National Flood Insurance Program at {BOQ1636F620.
APPROXIMATE SCALE IN FEET
500 0 500
i
i
1-
i
s.
NATIONAL FLOOD INSURANCE PROGRAM
.
FIRM
�
FLOOD INSURANCE RATE MAP
KING COUNTY,
WASHINGTON AND
-
INCORPORATED AREAS
1,
PANEL 983 OF 1725
{SEE MAP INDEX FOR PANELS NOT PRINTED)
CONTAINS:
COMMUNITY NUMBER PANEL SUFFIX
q
- 4 Y
KING COVIM.
UNINCORPM7ED AREAS 53 71 0M f
REWON, CITY Of 530088 0983 F
-
--
i
MAP NUMBER
.:
53033C0983 F
MAP REVISED:
MAY 16,1995
471
_
Federal Emergency Management Agency
3_
,r
T � -
.i
AE,D 2U-- p 21455
r' r_ Opp\
�. ` �.7•' I ` '\`= r ` ' ���� �� �� ,ff� C ,`�, r1EC �� AkF A C AkF
• %/ �✓ ii I
C C
Ev '°`g
fl 'IA P Ag
� u I
AgC T6
L M OHM
C
a5c ..AgC AgO
-1`d28
\
AMC I U Ag6}I
_ IBM' 29 Ur ! 27
169 9203 C A96
� I k9
ik
-- I o IAgC Rio
:�: I •I i� AmC II eo •� �11� � S'E. 6- I G -
'4 J:• I M
p ! AgU , 7 ,Am S .9 P6 RJpYlT6K.li'• ll �� I
93
��rd 194 • A B II'i Agc AgB
JCAmB•
AEG
' I a�AmC� :�JL •: -...:. j'AgC •n:� � `• I �1 ..
9 I ;I• x - EvB I -
b' All AeU tC
i ` Am6 :AgB
gp tt I Sk :P`r� I AgB AgC
32 - - eri+' 76 e Sk
•, + --I °, rd 1. Ag6 •`°. 9A 1'; 3LF
tF
v :� r - .!♦ ADO w il:A0 !
I Tank .
11 I n AgC
n ..
lr - n 'u
I m E3, It I n
Sk
AgC AgB
0 'N
* ' am ' 114Y 'S I' n
q i. :3 2 Sk 'I
j - AgB
• �'
N Ev8 �° AmB h �i • A
�'- •• AgC :.o{i - "�� i •n
O Ile
QQP Tu/(( I - AmB
I t too a I u
I AmC � it • tl
AkF AgC L. Ag6 AgC „ .• I � Sk �agC e'I Ur
Arne Sk AMC
• Ag6 • n:-: ...� ` Ago �°�• I=° No I T EvB
g AMC - -
AgC •Ag6 No I rca Fo I AgC
•r
No
u
AmC A>'C
AmC
• ti. • .•� • ' p� AmB j U AgC 't Age QO
AgC /' Q ( ', a Inc
r- -AS D AgC Tu 'n " v- 'S', : v6
pgEvB 'AgC Ev
B AmC l Ur t, E .I Na. A
_
v • • AmC .� _ i'■ '� emu. Ir', 0 �• '.
♦ o 'u ,
AmAgC,
C , ■ ■ ■ �� Nu �u a
u
AgC Sk NO 'n'gS u
AmC •F x'
=-•AMC U '
LU
Am •;•• o AgB AE
AgC Amc o * EvC
No _ No �\ ,Sk •ir
MIMI N
List of Drainage Problems near the Site Area
Petro Vista Level 1 Downstream Analysis
SEP.12.2002 12:19PM KC WLRD
NO.973 P.1/5
King Coun Water. and Land Resources (WLR) Division
201 S Jackson St, Suite 600
Seattie, WA 98 1 04-3 855
FAX
I "MOZZMag,
,� 1L. r
OVA I / •
Date: `! Id p
Number -of pages including cover sheet:
From: Cindy Torkelson
WLR Stonnwater Services St ctioa
Phone: 20 296.8171
Fax Number:
RE.- Level 1 AnulVsis
To follow is a list of complaints >recalved -by the Water and Land Resources Divisiou Drainage
Service-, Section. Complaint numbers beginning prior to 1990-X : have beea arcNved and are no
longer in our possession. They cm still be retrieved, if necessary, but will take additional time and
may not be beneficial to your research due to their
age, development which has occurred, etc, If you
are interested in reviewing the actual complaints, they can be pulled (time permitting) for your
review. Copies can be obtained for $ .15 per page, and $2.00 per page for plans,
Ke s:
j`1`t10 of 1"Yesti2Ation
Type of Problem
C ActionRequast
DCA Developnwnt/ConMvction
l3CW i3us4lcs''tnr Clown Watcr
DDM Drainage - Misacllaneaus
CCF Rssptrnse to lnquiry
DES Drainap — EtoslonfSedimenration
•CL Claim
US Drninagc—LandsliddEarth Movement
EH Enfaroement on Hold
1NQ Drainage — General Inquiry
ER EnforecmentRtyicw
MMA Maintenance - Aesthetics
S 1,52,sN3 Engineering Studies
MtvMF MAtitmanoc - Flooding
FCC,rMl7CS Facility CamplBurfs
MMG Maintenance - General
RR Facility Engineering Review
Z-04M Makirenauicc - Mowing
O LS lswsuit
MNM Maintenance — Needs Maintenance
NDA Nelghbo&ood DrainageA.ssistanoc
sWF SWM Fee Questions
WQC WatarQuailtyComplaint
WQI3 WuterQuality— Beat ManagementPractice5
WQE Water Qualityrznforc,:nwnt
WQD WaterQuality— Dumping
WQR Water Quality Cnginccring Review
WQI Watcr Quality — illicit Conneatlon
WQA Water Quality Audit
WQO Wotcr Quality -- Dthar
*Subject to Public Melogurt requirements 1. Receipt of written request far documents 2. Rcview and approval by Prosecuting AttomWs afYice
SEP.12.2!002 12:19PN KC WLRD
NO.973 P.2/5
Klua GaMty watBP ad Land ROOMMS Dl*lm - StormaatO SmIri a 98ellun
CIliWISk[t SMTA Nntrd : 0/1212002 9:26:35 AM
go rye 1 Cn s� ai
Cualmm
law
uns Psua
1974-0116
C
DRNG
12517
PETROVITSKY RD SE
CASCADE VISTA PLAT AREA
655F7
1975-0148
C
FLDG
12210
SE PETROVITSKY
RD
6561=7
1977-0073
C
DRNG
116TH AVE SF/PETROVI
HEADWATERSISOOS CRK
656E7
1982-0224
C
FLDG
11325
5E 176TH ST
CASCADE VISTA
656E7
1982-0548
C
11611i
/SE 175TH ST
DEPLETION OF WATER TO POND
656E7
. ; 1983-0361
C
DRNG
12
711, SE 176TH ST
ILLEGAL FILL
656F7
198-4-0406
C
FLDG
12210
PETROVITSKY RD
SE
CASCADE VISTA AREA
656F7
1984-0291
C
11417 SE 180TH
PV
SINKING YARD
656r=7
1BW298
C
FILL
I8504
112TH AVE SE
ILLEGAL MEAR 17409126TH AVE SE
606E1
1984-0304
C
17411
117TH AVE SE
FILL
GSW7
19B4-0310
C
FLOG
18019
118TH AVE SE
BENSON HILL AREA
656F7
1984-0315
C
DRNG
18504
112TH AVE SE
EASEM'7 B LKED11 7409 126TH AVE SE
&%F7
1964-0316
C
FILL
18504
112TH AVE SE
ILLEGAL @ 17409 126th AVE SE
656F7
1984-032-2
C
FLDG
12602 SE 176TH ST
66GF7
1984-0398
C
FLDG
12602
PETROVITSKY RD
656F7
1985-0235
E
DRNG
BsnSdy ROD -COMP BY CmDT
656F7
1985-0235
EH
WQI
PsnSdy ROD -COMP BY CmDT
65GF7
1985-0235
SE
7)
655F7
1985-0604
C
FILL
17232
11 STH AVE
SE
DRNG OBSTRUCTION
656F7
1585-1021
C
FILL
12234
SE
176TH ST
TO GRADING
656177
1966-0284
C
FLDG
12137
SE
172ND ST
FLOODED LOT
656F7
1986-8907
C
FLDG
17500
117TH AVE
SE
STEAM THRU AREA
656E7
1986-0907
ER
PIPE
17500
117TH AVE
SE
TRFR TO BALD-GRDG
656E7
1086-1047
C
FLDG
17665
119TH AVE
$I_
T6SMAL - OF PIPE
65BE7
1967-0409
C
FLDG
17665
111TH AVE
SE
INADEQUATE DRNG/PLUGGED 86-1047
65BE7
' 1987-0493
E
DRNG
17661
109TH AVE
SE
DITCH OBSTRUCTION
656E7
1987-0499
C
NOT IN FILE.
656F7
1987-0723
C
FLDG
17635
122ND PL
5E
SILTING, & POLLUTION-PETROVISKY CON
6561~7
1987-0817
C
FILL
12637
SE
176TH ST
WETLANDS/SE PETROVITSKY RD1126TH A
656F7
" 1987-0817
ER
WETLAND
12637
SE
176TH ST
BALD M ACT, SPT BALD GRDG.
656F7
1087-0895
C
FILL
18217
118TH AVE
SE
FOLLOW rRom GRADING
65BF7
1987-0895
E
FIHL
TO RDS FOR COST EST. IOORE.
656F7
1967-1123
C
DRNG
17324
117TH AVE
SE
HOLE AT END OF DRNG PIPE 96-0129,111
656F7
1987-1194
X
DRNG
16217
118TH AVE
SE
BLOCKED COUNTY DRAINAGE 87-0895
656F7
1988-0319
C
DRNG
17827
116TH AVE
SE
DRNG DffCHISLOPE/FRENCH DRAIN
656E7
1988-0382
C
DRNG
12505
SE
172ND ST
ORNG DITCH -COLOR OF WATERISOOS C
656F7
- 199D-0271
C
DRNG
1242-0
SE
PETROVISKY RD
DRAINAGE CONSTRUCTIONISTORM EVEN
656F7
Page 1 of 4
.�...... ....... .. r...Y., .... -.^"I FAnA9
5EP.12.2002 12:19PM KC WLRD NO.973 P.3r5
t
AID
�
TYP9 8f Pro611�a1 Min Of Pt'd� m
CO(Ipl]B11ts
n1m pan
1890-0566 CL
FLDG
12602
SE
PETROVITSKY RD
CI #12867 DUE MAY
656F7
1990-0664 E
MANHOI-r:� FAILURE
656F7
1990-0609 C
DRNG
17709
114TH PL
5E
SOGGY YARDAN CRAWLSPACE
656E7
1990-1530
C
FLDG
18427
112TH AVE
SE
656E7
1990-1531
C
FLDG
18427
112TH AVE
SE
656E7
1991-0031
G
FLDG
16217
124TH AVE
BE
STORM EVENTINO DITCH PONDING
656F7
1991-0099
CL
FLDG
12602
SE
PETROVITSKY
MEMO TO PA
6561`7
. 1991-0698
C
SPRING
11504
SE
178TH PL
PILLING IN OF POND
656E7
1991-0852
C
FLOODING
12615
SE
PETROVISKY RD
WATER FROM BANK
656F7
1 1991-0852
SR
FLOODING
12615
BE
PETROVISKY RD
WATER FROM BANK
656F7
1991-1023
C
FLOODING
11633
BE
1BOTH ST
WATER FROM ROADWAY
656F7
,.1991-1087
C
FLOODING
18216
124TH AVE
SE
LACK OF DRNGINEW HOUSES
656F7
1992-0571
C
DRAINAGE
12301
SE
172NO
DITCH CAPACITY- OLD PROBLEM
656F7
1
19924D571
SR
DRAINAGE
12301
SE
172ND
DITCH CAPACITY -OLD PROBLEM NOT ND
656F7
-1992-0609
C
DRAINAGE
172-25
125TH
SE
CASCADE VISTA STUDY
656F7
1993-0062
WOO
WOD97413
11930
BE
PETROVITSKY RD
656E7
1993-0062
WOE
WQD97413
11930
BE
PETROVITSKY RD
DUMPING FLYER - STORM DRAINS
656E7
F ' 1993-0181
C
DRAINAGE
17033
116TH AVE
SE
SOGGY YARD
656E7
1993-0186
WOO
WQ-OIL
12301
SE
172ND
SEE 91-1106
656F7
11993-0338
WQC
OIL DUMP
12000
SE
PETROVITSKY RD
SWM DIDNT ENF ACTION
656F7
- 'IB93-0570
C
DRAINAGE
17113
127THAVENUE
SE
WATI;RLINE LEAKS
656F7
1993-0644
WQC
DUMPING
11930
BE
PETROVITSKY RD
SEE 93-W62
656E7
1993-'f059
E
PIPE
12700
SE
PETROVITSKY
CASCADE VISTA/ BRODKA
656F7
1993-1059
ER
PIPE
12700
BE
PETROVITSKY
CASCADE VISTAI BRODKA
656F7
11994-0128
C
DRNG
12420
PETROVISKY RD
NEIGHBOR CONSTRUCTING POND
656F7
,1884-0144
C
DRNG
17925
116TH AVE
BE
POSS FILLING VIOLIACT PLAT MORNING
686E1
1994-0450
1:
WQC
_ ILI_IHKUP
12517
SE
PETROVITSKY RD
SEPTIC PROBLEM
856F7
1995-D200
C
DITCH 73
18204
11 BTH AVE
SE
LACK OF CONVEYAYNCE ON PVT PROPS
68BE1
-1995-0492
C
PONDDRN
11501
SE
173RD ST
MAINTENANCE OF PRIVATE RID FACILITY
656E7
A1995-0492
NDA _
PONDDRN
11601
5E
173RD ST
MAINTENANCE OF PRIVATE RID FACILITY
656F-7
1995-0492
RN
PONDDRN
11501
BE
173RD ST
MAINTENANCE OF PRIVATE RID FACILITY
656E7
'1995-0535
WQR
MAINP.
17421
120TH LN
BE
656E7
1 A995-0649
C
FLOODING
12602
BE
PETROVISKY RD
BRODKAIWORELY DISPUTE
656F7
1095-0700
E
DRAINAGE
12632
5E
PETROVISKY RD
OPEN LAWSUIT 13ETWEEN WORLEY AND
656F7
1995-0790
ER
DRAINAGE
12632
BE
PETROVISKY RD
OPEN LAWSUIT BETWEEN WORLEY AND
656177
11996-0591
C
CREEK
17405
116TH AVE
BE
PLUGGED CULVERT
656E7
'1996-0679
C
FLDG
12031
SE
170TH PL
IMPACT TO PVT PROPERTY FROM UNMAI
656F7
1996-0757
C
GRADING
17728
114TH PL
SE
SHEET FLOW FROM ADJACENT LOT
656E7
1996-0938
WQR
OIL -POND
17200
116TH AVE
SE
SEND LETTER WIMCL ATTACHED
656E7
1996-1135
C
W-0-R
17321
125TH AVE
SE
WATER PONDING AT END OF SAC NO RD
656F7
Page 2 of 4
nn JA w innna m T t Y . [ n gyms m, ve, C.1 n7 i 0003
5-EP.12.2002 12:19PH KC WLRD
NO.973 P.4/S
canow
TM Gf PrUm
Addno of PI'dft
Comm"
lb"s Palle
KI&11�18P
Gpt18
1996-1169
WQC
OIL
12105
SE
170TH PL
URBAN DRAINAGE DISCHARGE INTO CHA
656F7
199E-1236
C
FLDG
17023
113TH AVE
BE
APPARENT IMPACT TO PVT PROP OPEN
656E7
1996-1236
RR
FLOG
17023
113111 AVE
SE
APPARENT IMPACT TO PVT PROP OPEN
656E7
1996-2050
C
FLDG
12601
SE
PETROVITSKY
RE)
NAT CHAL SEDIMENT IMPACT CIP PROJ??
656F7
1996-2071
C
F'LDG
1 is2a
SE
160TH ST
INADEQUATE CONVEYANCE OFFSITE FLO 68SE1
1996-2071
R
FLDG
11828
SE
i BOTH ST
INADEQUATE CONVEYANCE OFFSITE FLO 686E1
1996-2125
C
DRNG
17311
117TH AVE
SE
TREES IN CHANNEL, DOWN FROM GAINS
656E7
1997-0588
C
DRAINAGE
17310
119TH LN LS
SE
PVT PROP SITUATION REMEDIED BETWE
656E7
1997-0692
C
DRAINAGE
17103
125TH AVE
$E
COTTONWOOD TREE ADJ TO STORM PIP
656F7
1997-1316
WQR
SPILL
12700
SE
172ND ST
656F7
1997-1477
WQA
-DUMPING
116XX
PETROVITSKY RD
DRAINING OF SWIMMING POOL;HEALTH D
656E7
1998-0052
C
DRAINAGE
17120
125TH AVE
SE
WATER PONDING ON PROP TECH ASST R
656F7
1998-0421
FCR
DEBRIS
17811
114TH PL
SE
GARBAGE DUMPED IN RAD TRACT
056E7
1998-0489
C
DRAINAGE
17321
125THAVE
SE
WATER PONDING WITHIN RD RNV
65BF7
�— 1098-0543
C
DRAINAGE
17232
116TH AVE
SE
UNCONTROU.ED FLOW FROM PARKING L
656E7
1999-0329
FCR
BAMBOO
12317
SE
179TH PL
NON NATIVE GROWTH IN R/D FACILITY
686Fi
1999-0363
WQC
MUDISILT
112TH
SE
176TH ST
CONST ACTIVITY CAUSE MUD/DIRT ON R
65eE7
r 1999-0364
C
DRAINAGE
17832
114TH PL
SE
FLOW FROM ADJ PROP ONTO COMPL_
656E7
1999-0466
C
FILL
12420
PETROVFTSKY RD
FILL ACTIVITY ON ADJ PROP IMP FLOW DI
656F7
1999-0606
C
FLOODING
17307
117TH AVE
SE
ROAD RUNOFF CAUSING FLOODING
65SE7
1R99-0657
C
FLOODING
17314
116THAVE
SE
ROADS CAUSING FLOODING SEE99-0608
656E7
2000-063
C
DRAINAGI;
17300
116TH AVE
SE
SEDIMENT IMPACT TO DRAINAGE CHANN
656E7
2000-0363
R
DRAINAGE
173DO
116TH AVE
sE
SEDIMENT IMPACT TO DRAINAGE CHANN
65BE7
2001-0014
C
DDM
12207
SE
172ND ST
REEQUEST FOR CLEANING OF DRAINGE C
656177
2001-0014
NDA-
DDM
12207
SE
172ND ST
REQUEST FOR CLEANING OF DRAINGE•C
658F7
T 2001-0014
R
DDM
12207
BE
172ND ST
REQUEST FOR CLEANING OF DRAINGE C
656F7
2001-0109
C
DDM
12510
SE
PETROVISKY
APPARENT FILLING AND DRAINAGE ACTI
656F7
2001-0117
C
DDM
12308
SE
PETROVISKY RD
DUMPING OF YARD WASTE AND CHANNE
656F7
- 2001-0190
FCR
MMA
114TH P
SE
& PETROVITSKY RD
CONCERN REGARDING POND SITE CONE)
65SE7
2001-0247
FCR
MMA
12317
SE
179TH PL
IDENTIFIED NOXIOUS WEEDS. BLACKBE
686F1
2001-0322
WQC
WOO
11631
SE
184TH ST
APPARENT GREY WATER DISCHARGE IN
68SE1
' 2001.0322
WQR
WQO
11631
SE
164TH ST
APPARENT GREY WATER DISCHARGE IN
68BE1
2001-0382
C
DDM
16924--1
125TH PL
SE
ROADS INDICATED PIPE SEPARATION OF
656F7
2001-0382
R
DDM
16924--1
125TH PL
SE
ROADS INDICATED PIPE SEPARATION OF
656F7
2001.WaS
WQC
WQI
SE 180T
& 118TH AVE
5E~
POTENTIAL GRAY WATER DISCHARGE_ C
6B6E1
-2001-0389
WOE
WOI
SE 180T
& 110TH AVE
SE
POTENTIAL GRAY WATER DISCHARGE. G
086EI
2001-03SS
WQR
WQI
SE 1BOT
& 1i8TH AVE
BE
POTENTIAL GRAY WATER DISCHARGE. (�
68BE1
2001-0684
C
MINIM
12301
BE
172ND ST
ALAN WORKING ON PROPOSED DRAINAG
655F7
` '2001-0726
C
DDM
12-216
SE
172ND $T
THIS PROBLEM IS ALREADY BEING ADDR
650F7
.2001-0742
FCC
MMF
11802
SE
PETROVISKY RD
APPEARS PONDING PROBLEMIS IN RID F
656E7
Page $ of 4
Afl/19/9f1f19 TMT 11.53 I`TY/i?T mn nin7i Enna
SEP.12.2002 12:20PM KC ILRD N0.973 P.5/S
Tm fff pftm
Am= a(ppowe
�p�tOlti> Thim Aaue
2002-0314
C
DDM
18524
114TH AVE SE
SHEETFLOW ONTO PROPERTY FROM LIP
686E1
2002-0359
FCC
MNM
17405
116TH AVE SE
CLEARING ACTIVITY ALONG STREAM CHA
656E7
2002-0381
G
DDM
11825 SE
184TH ST
SOGGY AREA IN YARD, MAY BE THE RES
686E1
F - 2002-0407
WQC
WQB
18836
113TH AVE
SE EXTENSION (WIDENING) OF EIS NG D!
656E7
2002-0535
FOR
MNW
17802
114TH PL SE
REPORTED INFESTATION OF TANSY RAG
656E7
2002-0614
WQC
WQD
SE 175T
& 120TH AVE SE
DISCHARE OF CARPET CLEANING LIQUID
656F7
2002-M14
a
WOE
WQD
SE 175T
& 120TH AVE SE
DISCHARE OF CARPET CLEANING LIQUID
656F7
Page 4 of 4
09/12/2002 THu 11: 53 [T I:/RX NO 51073 14005
SEP.16.2002 6:26AM KC WLRD NO.994 P.3f4
COMPLAINT 01-0742 JENNY CARTER at CA5CADE PARR CONDOS D96368
11802 SE PETROVITSKY ROAD TD 656E7
Investigated by ALAN MEYERS 11-I5-01
I toured the site about 1 FM the day after the Heavy rains had ended.
The Soos Creek channel on the north Bide of 1181h Ave SE between Units C
and D on the attached site plan was fairly full with a water level about
3-4 feet below the road level. The debris level along the edge of the
channel showed that a water level had been about 1-1.5 foot higher .than
the existing level. Based on the slow rotation of the water surface at
the south end of the channel, the channel was slowly draining south
through the 2-24inah culverts under 118e' Ave S$.
The tennis courts on the south side of the road were wet and looked as
though several feet of water had been ponded there recently. The WW-SE
channel located just south of the Recreation Building was very full and
appeared to be draining SE at the outlet of the culverts under liB"'.
Via phone, I talked to Carter on 11-20-01. She said the channel north
of IIS'J' had flooded to within about one foot of the top of its banks
and about 2 feet of water had ponded in the tennis courts on the south
Side of 119th.
After conferring in our office with Larry Oettle and Mike Malterich, I
called Carter back on 11-28-01 and told her the flooding in the channel
and tennis courts were normal for a heavy 3 day rainfall with partial
plugging of one or more downstream culvert entrances. I thanked her for
her complaint and gave her our 206-296-1900 complaint number and the
roads 24-hour complaint number at 206-296-8100.
The photos I took at the site were not found in say digital camera.
An 119/hnn'l zor no.An fmv/nv 7.rn G77r.1 Rnn,%