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-1111 .�.. :: <::> >: .:::::::::::::::::::::::;.. :: ::::. ::: . ...:::::::::::::::::::::::: OUR JOB NO. 6116 OCTOBER 1997 s ��v 101301ti Prepared By: ['DES G-96 1 BARGHAUSEN CONSULTING ENGINEERS, INC. 1 821 5 72ND AVENUE SOUTH KENT, WASHINGTON 98032 (425) 251 -6222 m�gGHAVS� AC 0 j CIVIL ENGINEERING, LAND PLANNING, SURVEYING, ENVIRONMENTAL SERVICES 4�1 6""'e TABLE OF CONTENTS 1.0 GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 UPSTREAM DRAINAGE ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 ON-SITE DRAINAGE ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.0 DOWNSTREAM DRAINAGE SYSTEM DESCRIPTION AND PROBLEM SCREENING . . . 5.0 RESOURCE REVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. BASIN RECONNAISSANCE SUMMARY REPORT . . . . . . . . . . . . . . . . . . . . . . . . B. CRITICAL AREA DRAINAGE AREA MAPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. FLOODPLAIN FLOOD WAY FEMA MAPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. OTHER OFF-SITE ANALYSIS REPORTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. SENSITIVE AREA FOLIOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F. SWM DIVISION DRAINAGE COMPLAINTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.0 U.S. DEPARTMENT OF AGRICULTURE SOILS SURVEY . . . . . . . . . . . . . . . . . . . . . . 7.0 WETLAND INVENTORY MAPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.0 CONCLUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ` . . . . . . . . . . 9.0 APPENDIX APPENDIX Exhibit A Vicinity Map Exhibit B Drainage Maps Exhibit C Off-Site Analysis Drainage System Table Exhibit D Assessor's Map Exhibit E Basin Study Exhibit F Sensitive Areas Folio Exhibit G Wetland Inventory Map Exhibit H Drainage Complaints Exhibit I King County Soil Survey 6116.003 [BAH/sm] 1.0 GENERAL INFORMATION The site analysis was conducted on July 9, 1997. The weather was cloudy and rainy. The proposed project consists of two retail buildings, a QFC Market/Retail Anchor. The site's total area is approximately 8.3 acres. The project is located in a portion of the Southeast quarter of the Southwest quarter of Section 10, Township 23 North, Range 5 East, Willamette Meridian, Renton, Washington. Based on a more localized description, the property is located on the northeast corner of the intersection of Duvall Avenue N.E. and N.E. 4th Street. Currently there are portions of the site that have impervious asphalt paving. However, the majority of the site consists of second-growth trees and underbrush. The general topography of the site is sloping toward the south at approximately 0 to 5 percent. 2.0 UPSTREAM DRAINAGE ANALYSIS The project receives upstream sheetflow from the north and northeast. The approximate area of sheetflow is 8.8 acres. From the site investigation, the majority of the upstream area is second growth timber and underbrush. It does not appear that our site receives a substantial amount of drainage from this upstream area. The majority of the upstream sheetflows into the existing wetland on the east portion of the site. 3.0 ON-SITE DRAINAGE ANALYSIS Current conditions for the project consist of sheetflow drainage that generally run from the north to the south of our project. The sheetflow is collected in a roadside ditch that runs east and west along N.E. 4th Street. The flow accumulates near the east property line and heads through an 18-inch culvert to the south. 4.0 DOWNSTREAM DRAINAGE SYSTEM DESCRIPTION AND PROBLEM SCREENING For a more detailed description of the downstream drainage system, please consult Exhibit "B," Basin Maps, and Exhibit "C," Off-Site Analysis Drainage System Table. The downstream drainage system for this project exits the site near the southeast corner. The drainage collects and heads under N.E. 4th Street through an 18-inch concrete culvert. On the south side of the street, the drainage exits into an open channel and heads toward the south. The open channel then enters into what appears to be a King County detention facility and then exits that facility to the southeast. The existing flow enters into an open channel and again heads in a southerly direction. Once the drainage reaches S.E. 132nd Street, it enters into an 18-inch tightline system that heads to the south through the residential neighborhoods. From a conversation with neighboring residents and a review of the assessor's map, it appears that King County has established drainage easements through the residential housing to convey upstream drainage to the south. From there, the drainage continues to the south until it flows into the Cedar River several thousand feet away from our site. 6116.003 [BAH/sm] Through a site investigation and conversations with the neighboring residents regarding problems in the downstream area, it appears that some flooding occurs in the area of S.E. 133rd Street during high level flows. Through a conversation with the resident, it appears through King County's site investigations that an undersized culvert was installed near the intersection of S.E. 135th Street and 142nd Avenue S.E. He also explained that King County plans to improve this culvert section in September of 1997. Other than this flooding and slight erosion in the open channels, the downstream area for this project appears to have no major capacity or erosion problems. 5.0 RESOURCE REVIEW The following is a description of each of the resources reviewed in preparation of this Level 1 Drainage Study: A. BASIN RECONNAISSANCE SUMMARY REPORT This site is included within the Cedar River Basin and the lower Cedar River Sub-basin. A Basin Reconnaissance Summary Map can be seen in Exhibit "E" along with the FEMA floodplain maps for this area. B. CRITICAL DRAINAGE AREA MAPS This site is located within the critical drainage area of the Cedar River. C. FLOODPLAIN FLOODWAY FEMA MAPS Please see Exhibit "E" for a copy of the FEMA map for this area. After review of the FEMA map, it was determined that our site is not within a floodplain. D. OTHER OFF-SITE ANALYSIS REPORTS A review of area maps, a site investigation, and basin study were reviewed for analysis and preparation for this Level 1 Drainage Study. E. SENSITIVE AREA FOLIOS Each of the sensitive area folios that was associated with this area was reviewed. After review, it was found that the subject property incorporates no sensitive areas. F. SWM DIVISION, DRAINAGE SECTION COMPLAINTS The drainage complaints for this area were reviewed that were adjacent to our downstream from our site. The list of complaints and applicable reports can be found in Exhibit "H" of this report. The underlined complaints are the ones that pertain to our project. Reports for these complaints can be obtained from King County upon request. 6116.003 [BAH/sm] 6.0 U.S. DEPARTMENT OF AGRICULTURE SOIL SURVEY The U.S. Department of Agriculture Soil Survey for King County has been incorporated in this report and can be found in Exhibit "I." 7.0 WETLAND INVENTORY MAPS Wetland inventory maps were reviewed for this project. It does not appear that the project lies within an area where any wetlands were inventoried. 8.0 CONCLUSION The downstream area for this project appears to have no major downstream-related problems. All drainage segments that incorporate the downstream area appear to have adequate capacity for existing flows. From our analysis of this project, we feel that there will be no adverse impact to the downstream system if development to the property incorporates standard City of Renton Stormwater Control Standards. 6116.003 [BAH/sm] EXHIBIT A VICINITY MAP 5 a h AV ^ PARK AY N <� s Y rk�7 •+E ' AV s GLINT GH AV s i;•.:- Jr r Imo" , `"F n v"',a. + a `K jy� :�;. pry • N f DI.N:c 4 K -MAY � ° �. O+n `��y. 'fir ,•?y � i•� :Eijpj� ��'. - �. . ,,�U.m" zurti �►."' �'`�Jlt_1��. 1400 ADE1tDEEN o ` c4f110 TH lr 8.,. EUINE AY .Ae w AY E .r a .'P L'. �^ '� s`s,'.�'( ^"'' C� ��.rr�rfi' 11 • ~T "' A4 7sM .sr M ♦* AY NE YTON tyy Ar �.jr''met,P �'.. `j �� 1100 ED.. S ItE Szlsr�a``r '4 � k C �• � �H � .. r AY H4RRI p z�wrAzrssal.� u 'f' fi� ,� .�..� •, _ l+�Cll. YI}d'.. '..�ief71 M 1R iR �NE �:..�i� - MOQ Ar ':. * ��G CZR E' JE g -yRi r/ �i�,�* �u _x N s II " 14 ,1SP.. F' a'°� M • RK MY ME i ~ t'a•+ KIRK N Ay � R �i fi `,t. �- F�' ;{ ■ �' i YMMAX7p A► '� �� r 4 tiME 19 - 17 A w '.rft 4fi. LL ,• '�' Rom' 41 ma VWIA AV X AY 1 pi 1MIN AV -XIMELTUR AV oN 'j fi.`.AA cllsr > > rJ r M°3 ' I•�_ � 1 /1• S '. e �"?Aoaw� N, i.00M �� s:.:. I_ T� 'AS T °r y gIR 8 UIiON�WI AY. NE R N ^ 1R v V D >: AV T •.\ `Syr, . : 1 I 3S q • r I }.., �4`' '1 KQ• 'o a r+vaa M1 TMyI I zt' rAsrgl. MNa ME I [T ME Arm Alf) �sr A R '; � � �,','�y tf* 'YQ r s,.• � � -- IR I �:. ,''sY' -r -- AV hMr Sz .� Obi r st NTH Ap. _137TN_- AY --NE �_+e I EPfl£Ri0r1 klr7antEt~j+ I a AY 1381H >fTM > =i AV = ALL AV) 1 iH uisr -� �' nAV S 4 " ` -- >R r 54 .. y ry SS I.r ■'. zA Y '< r u7ro wJW ~ 1 NO AV SE I AY I NE s .r IMTN AY SE AY E mu H ~ �rrsrti r 144TH AV m �i .�S sTl ar ..'+F .% A .sc �.Sv E � I4 �a - •--It, Ir5 X TiY '"Ac'.. N '� Y� r rrsr« rr sz �[G.S y3ir. Oo yQ �v3FT" t 4", 3 AV SE i iwn = 2 At; ,1 ;T.•9 .-,�• _ 11 147rH = 7 rl +,S( I R ` r _dr AV S� is^.* olrern�E rt 5E ^3•p c 7'�j urn ZIMLAV_SE I_ -r•la .Tt EXHIBIT B DRAINAGE AREA MAP o E 1�lst. t.......... • ., ..C6�T.:. S 1.t11 St ,+ 1 ,_.p........ 7th $t NE 6th P E ""� .. ;<.NE �,tn St t i 1+.)i-12, ;' `... i Z NE...�th' Ct€ f.,K-11 k W t SE 122nd St 17)10-+ .. 2 ».«........... _..... ;�•: ENE o n, i 6th P fe , .......< 1........... ..M «.., o k 5 t t CJ � , T. titi ......� ........ ... .... .. .. 14.36-314. a : NE 6th Ct o ..t...., :... .... ....... ......... .... . ...... Private Dr , SE 124th .............€ St ..........; . .. _ _ .,..........,..«.K. c ....... .M.. . � NE...St• � � � N,K-3 3 i / ..... r _.._. j ..... ... Q C 333 : i u.)e-� ; .. ....... .Z i .......... .W.; Z 7 14.19-8 i d ' 1 d Q c0 moo `... A MM:A . ���c _.:::«.......•. t'l"'Jt' ..,.,.:: ..............:..:........... _.......... ' t . IE c 19.B2-1 :19,)2-3 i 2-4 MA i : ... :_. 1 ...... _.. 19,112 7 �... ...... : j9.)2-10� : 't e 19,B2-9 j 1 + J 3r•d...Ct................ 5315 NW 1/4 x ax , � ps�� Am �I �I PMA mAP SC�1trE aoc� R it R -few loo 43 � I X 0 X !� IFitt$ I SR i L _=J — 11 D - 4 © lot I 1IRN I 1R 1 N x fit! p win - t SOS j� • cri 0 z 1 RENTON — 155ACLUAK ROAD 0 1!3 0 13 0 cl 0 (1,3 q13 quli fill Chi I? IN C-%C� 116. el' 400 0 cm 0 ,moo ❑ 1 � El 0 -All 400 ❑ cl O❑ Q "; I 400 \ ❑ 13Aroo r t-L, a it o FZI __== — 15 - o ( o C-h 550 CD Z. ___ _ ��°f �_`=-�!y rv`'"`"'� I)�''"`�^'1,r-1,,.�•,P.r-r+�^�.,.w,.•rv..v�n-'r'^ .r.,,r,., <. ::. 11 EXHIBIT C OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLE OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLE Basin: Cedar River Subbasin Name: Lower Cedar Creek Subbasin Number: ............ ...... ............................ ............. xx .................... -X-X-X-:-X ...... ....... ... . ..... .......... .............—.............. .............. ...............-........ .............. ....... betz -:-X-:-X-X: "...W36 .............. ............ ... ....... x. . ........... ...... .... ...........v. ........ ........... .............................................. X ............... ............... K.— XXX .......................... ..... X ...... ....... :........................................... .... ......... . ....... .. ..........:.X�:�X' See Map Type: sheet flow, swale, stream, Drainage basin,vegetation,cover, Ft Constrictions,under capacity,ponding Tributary area,likelihood of problem, channel,pipe, depth,type of sensitive area,volume overtopping,flooding,habitat or organism overflow pathways,potential impacts pond;size,diameter, surface area destruction, scouring,bank sloughing, sedimentation,incision,other erosion 1 18 Inch Concrete Culvert under N.E. 4th Street 1 0 - 80 None None None observed. 2 Open Channel Vertical ss, 10' bw, 3' deep 1 80 - 580 Slight erosion Erosion Slight erosion of bank due to earth lined high flows. 3 Open Channel 10' bw, 3:1 ss, F deep, 1 580 - 930 None None None observed. marshy area 4 18 Inch Concrete Culvert Outlet on detention pond 1 930 - 980 None None None observed. 5 Open Channel 3' bw, 2:1 ss, 2' deep, grass 1 980 - 1280 None None None observed. 6 18 Inch Tightline Tightline lined through housing 1 1280 - Flooding Flooding Neighbor reports flooding due development 2000+ to downstream undersized culvert. King County to fix in summer of 1997. 6116.004 [BAH/Icn] EXHIBIT D ASSESSOR'S MAP <479•Go> 12S /G.S. 3 2 TS ASSESSOR'S MAP �� r► � _ :ss . s. N h N N tt TR.B Nt N 63 a ` a` DL :j I nli /4i.0-7 2 74 t _ 6 f.J� Z. N e/sy GT 2 SO so Z7q.o2 _ .. .._ 324.02 0 % 274lk_ O Z73.8`) j 6 tiV N /62 I •� a Z N80. ""1j `h W Z N r' M tl tl Li m 3 ° N Z t S ^ 69 a g 0 v i N T !0 3o N / /3 .ZZ vi j Q 23 �L 10P t` Q m 8� oll I `�0} C io,993 0 Sk p 2l p \A., WA x � • I RENT [L.4. LUA . '04.0 71�' a6 03 h / /9 (v o, aJ IDrj N �✓ =/7 ' s68-03_-3E �v S. - _ 2 LC• 49 5-f v- \7 O b 2//�` v O 0 N I iso 3,./E d n ; SPG. pa Ae 0 17 r, -%0 \1 o RENTDN ORD. JSS9S QfN/O ! G 7 7o 2 3 373 3 r _ •sae/as• 45e0/559 '� fstro/36/O 0 tS79/ Ss6- -o RENTb�I o•tq•4470 RENrar! osty. SE� 128TH. ST. �'° .�s.,G .V.<Y•- � ti� SE. 1 8TH. 6L0.G¢ ter. ,c.�lp� y ,`, 67oc2414e8y S EIA 12 8 TH SST"- N M .slPE3 .ts [6 is /0 4420 347 ^ `� fLid -ES1 + 44 Z.7 4.687/ 03 ro ioe se �,�4 95 /7t.q 141.16 • I i 2 EXHIBIT E BASIN STUDY NATIONAL FLOOD INSURANCE PROGRAM NATIONAL FLOOD INSURANCE PROGRAM FIRM FIRM FLOOD INSURANCE RATE MAP FLOOD INSURANCE RATE MAP KING COUNTY, WASHINGTON AND KING COUNTY, INCORPORATED AREAS WASHINGTON AND INCORPORATED AREAS PANEL 981 OF 1725 (SEE MAP INDEX FOR PANELS NOT PRINTED) PANEL 982 OF 1725 (SEE MAP INDEX FOR PANELS NOT PRINTED) CONTAINS: COMMUNITY NUMBER PANEL SUFFIX CONTAINS: COMMUNITY NUMBER PANEL SUFFIX '. KING COUNTY. _ UNINCORPORATED AREAS 530071 0981 F l RENTON,CITY OF 530088 0981 F KING COUNTY, j UNINCORPORATED AREAS 530071 0982 F RENTON,CITY OF 530088 0982 F J .I MAP NUMBER 4 53033CO981 F I MAP NUMBER 53033CO982 F CY Nan, MAP REVISED: MAY 16, 1995 BAN MAP RE16 995 Federal Emergency Management Agency Federal Emergency Management Agency z , V) 0 o z 10 N WD mlo U w O C7 z z z W )[ a U CITY OF RENTON 530088 � I SOUTHEAST 126TH STREET Ll W N W 2 U Z s a x 0 v 3TH STREET 128TH W W N D W D Z I a W a' x co N x Z 0O O SOUTHEAST 12 WZ PLACE ::)_ = O U- U RING COUNTY 0 UNINCORPORATED AREAS CD 530071 z U u, D wZ Q � SOUTHEAST PLACE 132N0 NO�T $T 1ST FC- M L J W F-- Q ~ ImN w O x n- 0= o O (n U SOUTHEAST 2ND PLACE SOUTHEAST 136TH SOUTHEAST 136TH STREET STREET z ui z 3P0 ST���� O I z N Q SOOT 15 Q�Gl N Sao 1 SOUTHEAST SjPEF� RECONNAISSANCE REPORT NO. 13 LOWER CEDAR CREEK BASIN JUNE 1937 Natural Resources and Parks Division and Surface Water Management Division King County. Washington King County Executive Tim Hill King County Council Audrey Gruger. District 1 Cynthia Sullivan, District 2 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 9 Department of Public Works Parks, 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 Kramer. Assistant Division Manager Bill Jollv, Acting Division Manager Dave Clark, Manager. River R Water Derek Poon, Chief. Resources Planning Section Resource Section Bill Eckel. Manager. Basin Planning Program Larry Gibbons, Manager, Project Management 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 & Team Leader Bruce Barker, Engineer Matthew J. Bruenge, Geologist Arny Stonkus, Engineer Lee Benda, Geologist Rav Steiger, Engineer Derek Booth, Geologist Pete Ringen, Engineer Dvanne Sheldon, Wetlands Biologist Cindv Baker, Earth Scientist Di Johnson, Planning Support Technician Robert Radek, Planning Support Technician Randal Bays, Planning Support Technician Fred Bentler. Planning Support Technician Consulting Staff Mark Hudson, Planning Support Technician Sharon Clausen, Planning Support Technician Don Spencer. Associate Geologist. Earth David Truax. Planning Support Technician Consultants, Inc. Brian Vanderburg, Planning Support Technician John Bethel. Soil Scientist, Earth Carolyn M. Byerly, Technical Writer Consultants, Inc. Susanna Hornig, Technical Writer Virginia Newman, Graphic Artist Marcia McNulty, Typesetter Mildred Miller, Typesetter Jaki Reed, Typesetter Lela Lira, Office Technician Marty Cox, Office Technician P:CR TABLE OF CONTENTS I. SUMMARY 1 II. INTRODUCTION 1 III. FINDINGS IN LOWER CEDAR RIVER BASIN 2 A. Overview of Basin 2 B. Effects of Urbanization 4 C. Specific Problems 5 1. Drainage and flooding problems 5 2. Damage to property 6 3. Destruction of habitat 6 IV. RECOMMENDATIONS FOR ACTION 7 A. Reduce landslide hazards 7 B. Reduce erosion and flooding 7 C. Prevent future erosion and flooding with appropriate analysis,, 8 planning, and policy development D. Stop present (and prevent future) damage to habitat 3 by addressing specific problems in stream systems V. MAP 11 APPENDICES: APPENDIX A: Estimated Costs A-1 APPENDIX B: Capital Improvement Project Ranking B-1 APPEDDIX C: Detailed Findings and Recommendations C-1 I. SUMMARY The Lower Cedar River Basin, in southwest King County, is unique in its development pat- terns and the associated environmental problems that appear throughout the basin. Except for the city of Renton and areas on the Cedar River Valley floor, most of the development in the basin has occurred on the upland plateaus. Most of this development is recent and primarily residential. In addition, the plateau is the site of numerous sand and gravel mining operations and, in the southern uplands, an abandoned coal mine. Peat is also being mined north of Otter Lake. In some areas livestock are being raised on small farms; there are no major crop-related agricultural activities in the basin. The effects of development are most apparent where storm drainage is routed over the valley walls. Impervious surfaces on the plateau have increased the rate and volume of storm runoff, resulting in substantial erosion, siltation, and flooding below. In addi- tion, erosion and siltation have damaged or destroyed habitat in many tributaries, threatening the survival of fish. Habitat and water quality throughout the basin are also threatened by the filling of wetlands and the presence of large amounts of domestic trash in some streams. The reconnaissance team noted that the Peterson Creek system has so far remained in its natural, nearly pristine condition. Maintaining this quality should be a high priority in future basin planning capital project programs. Recommendations in the Lower Cedar River Basin include 1) designing and constructing appropriately sized R/D and other drainage facilities; 2) establishing stricter land use policies regarding floodplains, wetlands, and gravel mining; 3) conducting more detailed and comprehensive hydraulic/hydrologic analyses of proposed developments; and 4) preventing damage to the natural drainage system. The field team also recommends 5) restoring the habitat of several tributaries (e.g., cleaning gravels, revegetating stream banks, and diversifying streambeds for spawning and rearing) as well as 6) protecting the nearly pristine quality of Peterson Creek. U. UTMODUCITON: History and Goals of the Program In 1985 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, Soos, 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 investiga- tions used available data and new field observations to examine geology. hvdrology, and habitat conditions in each basin. Findings from these three basins led the King County Council to adopt Resolution 6018 in April 1986, calling for reconnaissance to be completed on the remaining 26 basins. The Basin Reconnaissance Program, which was subsequently established, is now an important cle- ment 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 use in the preparation of detailed basin management plans, and 3) capital costs associated with the early resolution of drainage and problems. The reconnaissance reports are intended to provide an evaluation of present drainage con- ditions 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 P:I_.0 1 Lower Cedar River Basin (continued) 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-case basis by County offi- cials responsible for reviewing applications for permit approvals and for choosing among competing projects for public construction. Nothing in the reports is intended to substitute for a more thorough environmental and engineering analysis possible on a site-specific basis for any proposal. III. FINDINGS IN LOWER CEDAR RIVER BASIN The field reconnaissance of Lower Cedar River Basin was conducted in January 1957 by Robert R. Fuerstenberg, biologist; Brice L. Barker, engineer; and Lee Benda, geologist. Their findings and recommendations are presented here. A. Overview of Lower Cedar River Basin The lower Cedar River Basin is located in southwest King County and is 27 square miles in area. It extends southeast from the mouth of the Cedar River on Lake Washington to approximately river mile 14.0. The boundary to the northeast is marked by a ridgetop connecting the city of Renton to Webster and Franklin Lakes; the boundary to the southwest runs along Petrovitskv Road to Lake Youngs. Renton is the only incorporated area in the basin. Other population centers include Fairwood, Maplewood Heights, and Maple Valley. Except for the city of Renton, most of the residential concentrations are located on the upland plateaus overlooking the Cedar River Valley. These upland developments are recent compared to the smaller established communities on the valley floor. The basin lies within portions of three King County planning areas: Newcastle in the northeast (which includes Renton), Tahoma-Raven Heights in the east, and Soos Creek (the largest of the three) in the west. Rural areas exist on the valley floor on both sides of the Lower Cedar River, from approximately river mile 5.50 to 13.00. These are limited to pastureland for horses, cows. and some sheep and several small "u-pick" fruit and vegetable farms. Similar areas are located on the southern uplands above the reach from river mile 5.50 to 7.00 and in the Lake Desire-Otter Lake area. The plateau is also the site of sand and gravel mining operations and, in the southern uplands, of the abandoned Fire King Coal Mine. Peat deposits exist west of Lake Desire and north and south of Otter Lake, and peat mining is being carried out north of Otter Lake. Present zoning allows for urban and suburban densities throughout much of the basin, particularly on the upland plateaus and in the Cedar River Valley from its mouth to appoximately river mile 6.50. Population projections for the year 2000 in the three plannign areas containing the Lower Cedar Basin are over 311,000, an increase of 47 P:LC Lower Cedar River Basin (continued) percent from the present. Most of this growth will occur in the Soos Creek Planning Area. Dominant geological and geomorphic features. The geology of the Lower Cedar River Basin is diverse. Geological formations exposed along the valley include sedimentary rocks, undifferentiated older glacial drift, extensive ground moraine deposits, recent alluvium along the Cedar River, and landslide deposits along the river and its tribu- taries. The sedimentary rocks, composed of moderately dipping sandstones. con- glomerates, mudstones, and shales, are exposed locally along the cliffs of the Cedar River Vallev near the mouth of the Cedar River. In addition, the Renton formation, composed of sandstones, mudstones, and shales with periodic deposits of coal, is also exposed along the lower portion of the Lower Cedar River Valley. Undifferentiated glacial deposits found here are composed of three or more till sheets, glacio-fluvial sand and gravel, glacio-lacustrine clay, and sand, and non-glacial sand, clav and thin peat. These lie over the sedimentary rock formations and are best exposed in cross-section along the cliffs of the main valley and major tributaries. The morphology of the Lower Cedar River Basin is dominated by the valley formed by the Cedar River. Valley walls are steep cliffs formed by landslides in glacial sedi- ments. A once extensive and meandering River, which created a wide vallev floor as it cut its wav westward, the Cedar today is diked for most of its length through the lower vallev. A narrow but extensive band of landslide deposits exists along the steep cliffs of the main river and its major tributaries. The landslide deposits consist of deformed blocks of glacial sediments and colluvium derived from slides or mass flowage, such as landslides and debris flows. Recent alluvial deposits fill the valley and major tributaries. Small, composite, alluvial debris fans exist at the mouths of the largest tributaries. Closed depressions, principally in the uplands, have lacustrine and peat deposits. The Lower Cedar River Valley has a high potential for erosion due to steep slopes and the existence of a clay laver that promotes soil failures. In addition, the confined nature of tributary channels between steep hilislopes promotes bank erosion during high flows. Numerous recent landslides are evident along cliffs of many of the steep tributaries and along the main stem of the Cedar River. These have been accelerated by the removal of vegetation and the routing of concentrated storm flows over steep slopes in areas where development has occurred. Hydrologic and hydraulic characteristics. The Cedar River Basin is composed of a complex drainage network consisting of the Cedar River and 17 tributaries. The larger tributaries begin in lakes or wetlands on the bluffs and flow through relatively flat, stable channels to the edge of the Cedar River Valley, then plunge down to the valley floor through steep, erodible ravines. Tributaries of this type such as Tributary 0304 (kith headwaters at Wetland 3111) and Tributary 0323 (which begins at Lake Desire). are found on the south side of the Cedar River. Another type of tributary collects surface runoff from urbanized areas, pastureland, and wooded areas. Tributaries 0302, 0307, and 0312 are examples of this type of tributary. Thev are intermittent (depending on rainfall), shorter in length, flow through shallower channels that are steeper at the bluffs and transport more material during times of P:C.0 3 Lower Cedar River Basin (continued) high flows. Some of the worst problems located during field investigation (see Appendix C for a full listing) occur on this type of tributary. Catchments 5, 6, and 12 have very infiltrative soils. Urban developments hvae utilized R/D poinds to effectively infiltrate all urban runoff before it reaches the valley hillslopes. The infiltrated runoff then reappears as springs. Two large lakes (Desire and Otter), together with four smaller ones (Shady, Peterson. Webster, and Francis) lie in the southeast third of the basin. Numerous large wetland areas exist in this section as well. The field team identified 10 potential wetland sites that had not been previously identified in the Sensitive Areas Map Folio (SAMF). The system of lakes and wetlands in this area effectively buffers the high flows draining to these tributaries. Habitat characteristics.. With few exceptions, usable fish habitat exists only in peren- nial streams (i.e., Trib. 0302, 0304, 0305, 0323, and possibly 0303). In other streams (e.g.. Trib. 0303 and 0310), steep gradients preclude fish use. Steep gradients also reduce fish use in the perennial systems (except for Trib. 0328). Habitat is in various stages of degradation in these systems; pools are being filled and gravels and debris shift regularly. In Tributary 0328 (Peterson Creek), however, habitat diversity is extensive, and the channel is not seriously degraded. At this location the field team observed at least three species of salmonoids. In general, the most diverse and least disturbed habitat in a tributary system occurs in the large wetland areas in the southeast third of the basin. Usable habitat for anadromous fish is found in the low-gradient portions of streams where channels cross the Cedar River Vallev floor. In these reaches, however, only spawning habitat is likely to be available, as the pools and woody debris necessary for successful rearing either do not exist or are quite limited. Excellent spawning jand rearing areas exist where pools and riffles are extensive, instream cover and bank vegetation are intact, and diversity of habitat types is abundant. B. Effects of Urbanization in the Basin Flooding, erosion, and the degradation of habitat associated with development in the Lower Cedar River Basin are most apparent where development has eliminated vege- tation along the edges of the valley and where stormwater has been routed down channels and swales. The removal of vegetation, such as trees. above and below the edges of vallev walls, as well as the discharging of stormwater over the valley wall, has resulted in tension cracks and landslides that are endangering some houses. The sedi- ments from these failures are depositing in streams and on valley floors and damaging fish habitat and private property. Discharging stormwater from increased impervious areas into steep tributary channels and swales is seriously destabilizing channels and vallev walls; this in turn results in channel do%vncutting. bank erosion, and landslides. The sediments from these problems often degrade fish habitat and settle out on pri- vate property along the valley floor. Two serious instances of development-related erosion occurred during the November 1936 storm: 1) culverts rerouting the stream were plugged. causing the formation of a new channel that destroyed portions of roads on Tributary 0314; and 2) new, uncom- t':LC 4 Lower Cedar River Basin (continued) pacted fill adjacent to new residences near collection point 5 was washed partly away during the storm, causing landsliding and gullying. Future problems will be similar to these, as commercial and residential developments increase flow rates and volumes by decreasing natural storage and infiltration. This is expected to occur if wetlands on the upper plateau are encroached upon or lost (e.g., on Trib. 0304 at RM 2.30 and on Trib. 0304A at Rm 1.60). The preservation of wetlands and streambank vegetation and the attenuation of storm flows are essential in this basin. C. Spec Problems Identified The steep valley sideslopes through which streams pass and the often dense upland development result in a number of similar problems that repeat themselves throughout the Lower Cedar River Basin. The most significant of these are outlined and discussed below. 1. Drainage and flooding problems are often the result of several conditions: a. Undersized culverts and inadequate entrance structures. The most notable area is on Tributary 0306 at river mile .30, where a culvert here was blocked by debris carried downstream by the stream and caused erosion and flooding of Fairwood Golf Course. The blockage was compounded by the fact that the culvert was undersized: the problem will worsen as flows increase from upstream development. b. Serious instream erosion and subsequent downstream sedimentation. These have been caused by three main factors: 1) runoff from residential developments on the bluffs above the valley, 2) compacted pastureland due to livestock, and 3) runoff from impervious areas originating at gravel pits. These problems will continue and worsen until mitigative measures are taken. (See Appendix C for specific examples.) c. Undersized rechannelized streams. Tributaries on the vallev floor are too small to carry the increased flows originating in developed residential areas along the top of the bluffs. For example, Tributary 0302 at river mile .25,the channel along Maplewood Golf Course, overtops and floods during storms. d. Construction in wetland and floodplain areas, Manv of the wetlands on the south side of the Cedar River are peat bogs, and roads built through them continue to settle each vear, increasing the amount of flooding on the road. For example, the road crossing with Tributary 0323B north of like Desire will experience more severe flooding as the road settles. C. Discharging of stormwater at the top of steep banks. At river mile 2.20 on the Cedar River, a trailer park (constructed on the edge of the cliff) discharges its drainage down the vallev wall. Increased flows erode the steep valley, depositing sediments on the valley floor, blocking channels and causing flooding. These problems will eventually_ stabilize, but only after a large quantity of soil has been eroded. 11:LC Lower Cedar River Basin (continued) 2. Damage to property is being caused by three factors: a. Landslides and potential landslides Landslides are accelerated by the removal of vegetation on steep slopes in preparation for residential construction and/or by the routing of storm flows over hillslopes. For example, a large landslide has already occurred in the front vard of a resi- dence on the Cedar River at river mile 7.30. b. Sedimentation (from landslides). Sedimentation and channel and bank ero- sion are damaging private property along the valley floor (Trio. 0299 and 0310). C. Flooding during storms. Flooding has been brought on by the effects of development and associated changes to the natural drainage systems in the basin. (See "B" above.) 3. Destruction of habitat is being caused by four conditions a. Sedimentation of pools and riffles and cementing of gravels These problems, the result of severe erosion and the transport of bedload material, have been caused by upland developments in the basin and the presence of associated impervious surfaces, which increase the rate and quantity of surface runoff. Sedimentation and cementing of gravels in streambeds destrov natural spawning and rearing habitat. On Tributary 0307 at river mile .40 and Tributary 0305 at river miles .95, 1.20, and 1.70, recent high flows have eroded the streambed at least one foot, contributing to a serious siltation problem downstream. -:Heavy bedload transport is evi- dent in all systems of the basin except Tributary 0323. In Tributary 0303 at river mile .25, fine sediments are accumulating in gravels that may be used by resident fish. In Tributary 0304 between river miles .95 and 1.20, pools are being filled by sands and gravels and rearing habitat is being rapidly lost. b. Channelization of stream beds. Loss of habitat through channelization has occurred in all the major streams of the basin, but most noticeably in those reaches that cross the vallev floor. These reaches lack habitat diversity, reducing fish use for spawning and rearing. Channelization has damaged or destroved. habitat in several reaches that were once heavily used by fish: these include Tributary 0302 between river mile .30 and 40. Tributary 0304 between river miles .05 and .19. Tributary 0305 between river mile .20 and .75. and Tributary 0328 from river mile 1.10 to 1.40. These systems cannot afford a further reduction of habitat and still remain viable fishery resour- ces. C. 'I'hc accumulation of trash in stream beds This problem occurs in close proximity to residential areas. Trash degrades water quality and is visually unpleasant. Tires, appliances, furniture, and other trash have been thrown into Tributary 0302 at river miles 1.00 and 1.10 and in Tributary 0303 at river mile .35. P:LC 6 Lower Cedar River Basin (continued) d. Wetland encroachment. Encroachment destroys habitat and eliminates natural water filtration and storage for surface runoff. Examples of this problem were observed on Tributary 0304 at river mile 2.30, Tributary 0308 at .80, and Tributary 0304A at river mile 1.80. Many wetlands have already been completely lost through filling, for example on Tributary 0306A at river mile .55. Suspected violations were forwarded to Building and Land Development for enforcement. IV. RECOMMENDATIONS FOR ACTION The primary recommendations for action in the Lower Cedar River Basin addresses current severe problems related to erosion, habitat destruction, and flooding. Prevention of these problems will be accomplished by controlling locations and densities of new development and providing adequate R/D facilities for stormwater. A_ Reduce landslide hazards by. 1. Including sensitive areas not previously mapped on the Sensitive Areas Map Folio (SAME). See Appendix C for a full listing of sensitive areas. 2 Establishing building setbacks along cliffs and native growth protection easements along steep ravines. 3. Discouraging or eliminating the routing of stormwater over cliffs, unless adequate tightline systems can be constructed to convey flows in a safe, nonerosive manner to the bottom of cliffs. 4. Decreasing peak flows by constructing la ber R/D facilities to lessen the landslide and erosion occurrence along tributary slopes. B. Reduce erosion and flooding in the basin by improving surface water management: 1. Direct the Facilities Management Section of the Surface Water Management Division to evaluate existing storm-detention and conveyance facilities to deter- mine whether they are properly sized to-meet current standards. Evaluation should begin with all single-orifice R/D facilities. 2 Consider areas other than wetlands as regional storm-detention facilities. Tributary 0300 at river mile .42 is the site for a proposed dam, for example. 3. Utilize existing lower quality wetlands (those rated other than #1) as regional storm-detention facilities. Wetlands 3102 and 3142 could provide more live storage, for example. 4. Review channel and culvert capacity for conveying existing and future runoff, and establish floodplain areas in regions of slight gradient for existing and future runoff conditions. 5. Promote the infiltration of surface water through the use of retention facilities and open channels instead of pipes where the soil and slope conditions permit. Collection points 5. 6. and 12 on plateaus have such soil conditions. P:LC 7 Lower Cedar River Basin (continued) C. Prevent future problems of erosion and flooding with appropriate analysis, planning, and policy development related to surface water management: L Conduct a detailed, comprehensive hydrauGe/hydrologic analysis of any proposed developments to determine impacts on the drainage courses downstream. This is especially critical for areas on the upper bluffs and plateau, which drain over steep, sensitive banks above the Cedar River. 2. Conduct a study of the impact of locating infiltration ponds utilized near the edge of the bluffs to determine their effect on seepage faces on the lower face of the bluffs. This might be accomplished with a computer-based numerical model of the groundwater flow. 3. Require the tightlining of storm drainage down steep or sensitive-slopes when thev cannot be directed away from the slopes. This is done by piping the flow down the slope and discharging it at the bottom with adequate energy dissipation. Manv of the intermittent tributaries flowing down the banks should be tightlined as urban development increases flow to them. 4. Construct new R/D ponds with filter berms to improve water quality and reduce fine sediment loads. New R/D ponds should have two cells with gravel-berm filters and vegetated swales at the inlet and outlet. Consider Tributaries 0304, 0304A, 0302, and 0303 as sites for this type of facility in order enhance water quality. 5. Maintain natural vegetation on streambanks and floodplains. This is especiall} important for relatively flat channels flowing on the plateau before they reach the steep bluffs because these channels and their floodplains will attenuate flows during times of heavy runoff. 6. Maintain buffer areas around wetlands. Many of the tributaries on the south side of the Cedar River headwater at wetlands. These wetlands act as natural storage areas during storms. 7. Reevaluate King County policy regarding permitting for gravel mining on steep, sensitive slopes. 8. Include the city of Rention in future intcrlocal agreements for planning and capi- tal improvement projects where city and county interests overlap. D. Eliminate present damage to habitat and prevent future damage by addressing specific problems in the stream systems. The following activities should be coordinated among King Countv. the Muckleshoot Indian Tribe. and State Departments of Fisheries and Game: 1. Reduce damaging storm flows with greater detention volume and lower release rates at upstream developments. 2. Implement restoration projects on Tributaries 0304 (river mile .00-.20), Tributary 0305 (river mile .20-.30), Tributary 0303 (river mile .25-3,5). and Tributary 0328 (river mile 1.10 -1.40): P:LC 8 Lower Cedar River Basin (continued) a. On Tributary 0304: Clean streambed gravels, add habitat and bed-control weirs, and plant bank vegetation for shade. b. On Tributary 0305: Construct a new channel and move stream from road- side channel to its new location on adjacent lands. Implement a full restoration project to provide channel meanders, habitat structures, pool/riffle enhancement, streambed gravel replacement, and revegetation. C. On Tributary 0303: Move stream from present channel to a location further north, away from the roadside. If relocation is not possible, these minimum steps should be taken: Add habitat structure to existing channel with root masses, deflectors, boulder clusters, and other features; revegetate channel banks with shrubs and small trees; enhance stream crossings with bottomless pipe arches. d. On Tributary 0328 (Peterson Creek): Add habitat structure by replacing the straight, shortened channel with a more natural, meandering one; place habitat structures (such as root masses, deflectors, cover logs, and boulder clusters) throughout the channel; and revegetate banks with shrubs common to adjacent riparian zones (salmonberry, ninebark, or dogwood, for example). 3. Protect the Peterson Creek system (Tn-b. 0328) in its present, near-pristine state. This will include not only the restoration outlined in section A above, but also the adoption of land use management regulations to prevent future habitat destruction: a. Protect all existing wetlands within the subcatchments of Peterson Creek. Employ wetland buffers at least 100 feet wide without exception. b. Restrict development in the critical headwater area (drainage, habitat, water quality) bounded by Lake Desire, Otter Lake, and Peterson Lake to rural densities. C. Designate and protect streamside management zones of at least 100 feet from the ordinary high-water mark (OHWM) along the main stem of the creek. Use 25 feet from the OHWM on tributaries. d. Preserve floodplains and their forests for dynamic retention of sediments and water. C. Restrict vegetation removal in streamside/wetland management zones. f. Size R/D facilities to store the 100-year stone at a two-to-five-vear release rate. Use the two-cell type of pond with a forebay, a gravel filter, and a vegetated swale outflow where feasible. g. Regulate more closely all septic tank and drain-field installations as well as maintenance schedules, particularly in the Lake Desire, Otter Lake, and Peterson Lake drainage areas. P:LC 9 Lower Cedar River Basin (continued) h. Work with the State Department of Ecology to establish minimum stream_ flow requirements for Peterson Creek and Lake Desire tributary. 4. Develop and promote public education and involvement programs for basin awareness. Work with schools, environmental groups, and the civic and business communities to conduct educational and restoration programs. P:LC 10 " LOWER CEDAR RIVER BASIN ' �• •\,� Satin Boundary u catchment Boundary Collection Point Stream 0299 Tributary Number W , 03115 Proposed Project La x. 2 Miles • _ JUIY,2987 i 19 a y. 9 o o , o 3109 woo w M i 3117 : V � S L s 3121 °� ' , ti, 3113 o g �� r 3116 p3z 3122 1 w a l � Y y, w 3115 12 Al. 31f , 7 MMM V7M7 r \ 1V APPENDIX A ESTIMATED COSTS: PROPOSED CAPITAL, IMPROVEMENT PROJECTS LOWER CEDAR CREEK BASIN Indicates project was identified by Surface Water Management office prior to reconnaissance. NOTE: All projects are located on map included in this report. Project Collect. Estimated Costs Number Point Project Description Problem Addressed and Comments 3105` 10 Enhance 2200' of Trib. 0305 from Mitigates flooding of King $115,000 Cedar River to Elliot Bridge. County park land. (NOTE: This project was proposed by Surface Water Management, is in the design phase, and will be constructed by 1939.) 3109° 10 Secure easements to wetland located Better utilizes wetland's storage $186,000 in Cascade Park and construct a berm capacity to address peak flows from at the outlet. Replace existing surrounding urban area. catch basins with control structyres. Project should be justified by a basin study. Wetland rated #2. ("This wetland will require further biological evaluation before R/D design and construction.) P:LC.AI'A A-1 Project Collect. Estimated Costs Number Point Project Description Problem Addressed and Comments 3111 Secure easements to outlet to Francis Will provide additional storage $175,000 (Wetland lake and 1100' of channel from lake to mitigate anticipated future 3136) to SE 134th St. Construct a weir to increased flows. raise lake level 1', and enhance 1100' of Trib. 0317. Should be justified by a basin plan. Wetland rated #1. (']'his wetland will require further biological evaluation before R/D design and construction.) 3112 19 Secure casement for outlet to wetland Will provide additional storage $117,000 (Wetland and replace existing weir with a for anticipated future peak flows. 3142) concrete-slotted weir. Should be justified by a basin plan. Wetland rated #2. ('This wetland will require further biological evaluation before R/D design and construction. 31 14' Sccure easement to Wetland 3150 and Addresses anticipated increases in $134 000 (Wetland construct a containment berm and flow caused by development. 3150) control structure at the outlet. Project should be justified by a basin plan. Wetland rated #2. ('Phis wetland will require further biological evaluation before R/D design and construciton.) 3115 14 Install detention pond and 1.000' Mitigates severe erosion and $361.000 of tightlinc. Project is indcpcn- flooding during times of high dently justifiable. flows. 11:1.C.Al'A A-2 Project Collect. Estimated Costs Number Point Project Description Problem Addressed and Comments 116 21 Raise existing road embankment Mitigates seasonal flooding of Lake $73,000 24'. Project should be indepen- Desire Dr. SE caused by road bed dently justifiable. (Refer to settling in the peat bog. Roads Division.) 3117 lei Install 1,400' of tightline, a Mitigates severe erosion, sediments $501,000 sediment trap, and 700' of channel deposited on County roads, and from Jones Rd. to Cedar River. flooding during times of high Project is independently justi- flows. fiable. 3118 10 Install 300' of 36" culvert, a new Will prevent blockage of culvert $47,000 inlet structure, manhole, and catch and the accompanying flooding and basin. Project is independently erosion of Fairwood Golf Course and justifiable. mobile home park below. 3119 4 Construct a detention dam and Project location is ideal because $159,000 control structure in a deep it addresses flows from a large channelized section of Trib. residential area before they reach 0300. Project is independently the steep, sensitive area next to justifiable. the Cedar River. 3120 15 Construct a sedimentation popd and Mitigates flooding of residence and $163,000 1.000' of channel from Jones Rd. to sediment deposition on Jones Rd. Cedar River. Project is indepen- dently justifiable. P:LC.AI'A A-3 Project ColICCL Estimated Costs Numbcr Point Project Description Problem Addressed and Comments 3121 7 Secure casement to wetland and con- Addresses increased flows in Trib• $371.000 (Wetland struct a containment berm and concrete 0304 and 0304A from residential 3102) weir at outlet. Project should be developments. justified by a basin plan. Wetland rated #2. Biological assessment is needed to assure that this project does not decrease habitat values. 3122 11 Purchase existing ponds on Fairwood Mitigates flooding and erosion $342,000 Golf Course and expand to provide downstream. (Treater flow detention. Project is independently justifiable. i':LC.APA A-4 APPENDIX B CAPITAL IMPROVEMENT PROJECT RANKING LOWER CEDAR RIVER BASIN Prior to the Lower Cedar River Basin field reconnaissance, 12 projects had been identified and rated using the CIP selection criteria developed by the Surface Water Management (SWM) and Natural Resources and Parks Divisions. Following the reconnaissance, 13 projects remain proposed for this area. They include eight new, previously unidentified and unrated projects. These displace seven previously selected projects, which were eliminated based on the consensus of the recon- naissance team. Projects were eliminated for several reasons: two sites were annexed by the city of Renton, two projects were found to be unnecessary, two sites were categorized as #1 wetlands (and are ineligible), and one project was determined to be infeasible. The previous SWM capital improvement project list for the Lower Cedar River Basin had an esti- mated cost of $2.710.000, while the revised list increases to an estimated cost of S2,784,000. This 3 percent increase in estimated capital costs is due to the addition of projects after the reconnaissance. The following table summarizes the scores and costs for the CIPs proposed for the Lower Cedar River Basin. These projects were rated according to previously established SWM Program Citizen Advisory Committee criteria. The projects ranked below are those for which the first rating question, ELEMENT 1: "GO/NO GO." could be answered affirmatively. Projects with scores of 100 or higher can be considered now for merging into the "live" CIP list. RANK PROJECT NO. SCORE COST 1 3122 103 $3421000 2 3118 90 87,000 3 3120 75 163,000 4 3109' 67 186,000 5 3121 65 371,000 6 3117 60 501,000 7 3115 60 361,000 8 3116 55 73,000 9 3114` 28 134,000 10 3111' 25 175,000 11 3112' 17 117,000 12 3119" 15 159,000 13 3105 12 115.000 TOTAL $2,784,000 * Projects proposed prior to the Reconnaissance Program P:LC.APB B-1 APPENDIX C DETAILED FINDINGS AND RECOMMENDATIONS LOWER CEDAR RIVER BASIN ° All items listed here are located on final display maps in the offices of Surface Water Management, Building and Land Development and Basin Planning. Trib. & Collect. Existing Anticipated Item" River Mile Point Category Prop. Proi. Conditions and Problems Conditions and Problems Recommendations 1 -- 5 Geology Gullying and landslides in Continued erosion. Recompact fill, revegetate, uncompacted fill in new and drain adequately. development near edge of steep hillslope. 2 -- 13 Geology Small landslide has formed None (natural failure). None. debris flow (11/86). Sedimentation in yard of residence. 3 0299 4 Geology Landslides in sedimentary Natural failure. None. RM 2.6 rock in cutbanks adjacent to railroad. 4 0299 16 Geology Drainage from residential Increasing erosion. Provide adequate R/D to RM 9.65 area is resulting in attenuate flows. gullying in swale. P: LC.APC C-1 Trib. & Collect. Existing Anticipated Itcm River Mile Point Category Prop. Proi. Conditions and Problems Conditions and Problems Recommendations 5 0299 13 Geology Horse farm in uplands has Continued high erosion and Develop R/D at horse farm RM 12.1 created extensive imper- sedimentation. to attenuate peak flows. vious surfaces, resulting See Project 3115. in channel scour, bank erosion, landslides, and sedimentation at mouth of basin. Residence overcome with sediment. 6 - 13 Geology Landslide terrain for sale Site of future mass erosion. Prohibit development here. by realtors. High risk for Notify Building and Land landslides, flooding (from Development. Add area to springs). SAMF. 7 -- 7 Geology Large-scale landsides Natural process. None. adjacent to Cedar River due to springs and cutting of toeslopes by streams. Appears to be natural. 3 -- 2 Geology Gullying in valley wall, Unknown. None. possibly from natural springs. 9 -- 14 Geology Landslide debris flow from Existing tension cracks Revegetate hillslope with residence on SSE 147th Pl., indicate future instability. trees and shrubs. Renton. P: 1_.C.APC C-2 Trib. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proi. Conditions and Problems Conditions and Problems Recommendations 10 0299.1A 21 Hydrology 3116 Frequent flooding of Road located on top of peat Elevate the road 34' by RM .08 county road caused by low bog and will continue to filling on top of the road embankment. settle, aggravating flooding present road embankment. problem. Also stabilize embankment. 11 0300 4 Geology Extensive channel and Problems will continue. Provide adequate R/D in RM .00-.40 bank erosion and numerous uplands. (See Project landslides due to 3119.) development-related stormwater. 12 0300 4 Hydrology 3119 Development-related peak Increased erosion on Construct detention dam in flows have caused sig- hillslopes below. deep, channelized reach of nificant bank erosion. Trib. 0300. 13 0300 4 Hydrology 3109 Collection point 4 has Degradation of Trib. 0300 Construct berm and standard RM 1.40 been nearly completely from RM .42 downstream. This control structure at outlet urbanized. section is very steep and to Wetland 3120 in Cascade susceptible to erosion. Park. 14 0302 6 Geology Channel downcutting and Will continue at same level Control storm flows from RM .50 bank erosion. or increase. uplands. 15 0302 6 Geology Bank erosion (medium den- Increasing erosion with Provide adequate R/D in RM .80-1.00 sity) at meanders and increasing flow from devel- uplands as area develops. obstructions. opments. P: LC.APC C-3 Trib. & Collect. Existing Anticipated Itcm River Mile Point Category Prop. Proi. Conditions and Problems Conditions and Problems Recommendations 16 0302 6 Geology Gully erosion from broken None. Culvert has been None. culverts. repaired. 17 0302 6 Geology Severe gully erosion Continued erosion. Tightline flows to RM .60-.40 creating small valleys main stem. from daylight culverts. 1s 0302 6 Habitat Stream channeled along While fish now use this Add habitat diversity RM.35 golf course road. No reach, lack of habitat will (e.g., structures, overhead overhead cover. No habi- eventually reduce popula- vegetation). Gain tat diversity. tions. easement to restore mean- ders, if possible. 19 0302 6 Ilydrology Tributary drains down Problem will worsen as Construct detention dam RM .45 steep bluffs on north development upstream upstream of golf course. side of Cedar River, continues. carrying debris and flooding Maplewood Golf Course. 20 0302 6 Habitat Water supply dam. Full As impoundment fills, storm- Dredge pond and maintain RM .50 barier to upstream water will flood over bank. it as sediment catch. migration. Impoundment Structure may fail. is filling with sediment. 21 0302 6 Habitat Severe gullying from right Will continue to erode until - Tightline downslope. RM .90 bank corregated metal reaches till layer. - Add velocity attenuator at pipe. Heavy sediment stream. delivery to stream. P: LC.APC C-4 Trib. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proi. Conditions and Problems Conditions and Problems Recommendations 22 0302 6 Habitat Trash in stream (auto, Area adjacent to corridor, - Remove trash. RM 1.00 tires, appliances). will continue to collect - Distribute educational trash and debris. Further materials to streamside worsening of water quality, residents. sedimentation, erosion. - Cite violators, if problem persists. 23 0302 6 Habitat Trash in stream. Water Area adjacent to corridor, - Remove trash. RM 1.10 quality problem, will continue to collect - Distribute educational unsightly. trash and debris. Further materials to streamside worsening of water quality. residents. Cite violators, if problem persists. 24 0303 6 Geology Extensive bank erosion in None. Increase R/D volumes, slow relcasc upper portions of tribu- rate to noncrosive levels. tary. 25 0303 6 1labitat Habitat suitable for resi- Sediments will eventually - Control stormwater volumes RM .25 dent fish. Sediment accu- cover gravels. Habitat and discharge rates from mulating. will become unsuitable for developments. fish use. - Manually clean gravels when necessary. 26 0303 6 Habitat Trash and litter in Further decreases in water - Remove trash and litter. RM .35 channel affecting water quality. - Distribute educational materials quality, causing erosion. to streamside residents. - Cite violators, if problem persists. P: LC.APC C-5 Trib. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proi. Conditions and Problems Conditions and Problems Recommendations 27 0304 7 Habitat Landslides contributing Sediment will continue to Maintain riparian corridor RM .40 sediment to channel. Heavy enter system until landslide with setbacks at least 50' deposition in pools, at stabilizes. from tops of banks. obstructions, even in riffles. 28 0304 3 Habitat Horses have access to Further decreases in water - Encourage residents to fence RM 2.10 stream, causing some bank quality, bank erosion likely. channel back 15' from ordinary deterioration and possibly high-water mark. affecting water quality. - Limit access to livestock to one or two points along stream. 29 0304 4 Ilydrology Flooding caused by failing Problem will continue until - Problem referred to Main- RM 2.30 R/D at 176th St. & 146th outlet structure is tenance section of Surface Ave SE. modified. Water Management Division. 30 0304 3 Habitat Encroachment occurring Wetland likely to be - Require encroaching fills RM 2.40 along all boundaries of reduced slowly until it is to be removed. this headwater wetland. completely destroyed. Loss - Establish specific buffer of storage, filtration, around this wetland. organic production, and - Enforce sensitive areas wildlife habitat. ordinances and regula- tions. 31 0304 7 Gcology Several gullies due to Problem will continue. - Tightline drainage. RM .80 daylight culverts; a few have recent landslides. P: l..C.APC C-6 Trib. & Collect. Existing Anticipated Item River Mile Point Category Prop. Pro*. Conditions and Problems Conditions and Problems Recommendations 32 0304 7 Habitat Extensive riffle (to RM Gravels risk becoming - Enhance habitat by addi- RM .00 .15. Creek channeled. No cemented. Few resting areas tion of woody debris in woody debris, little bank for upstream migrating fish. stream. vegetation. Steelhead, - Revegetate bank. coho spawners here. - Enhance pool/riffle ratio. 33 0304 7 Habitat Debris jam may be a Debris will continue to - Selectively remove debris RM .20 partial migration barrier. accumulate. Channel will to allow fish passage. likely divert or jam will - Stabilize large woody fail, releasing accumulated debris. sediment. 34 0304 7 Habitat Debris jam. Bed drops 3' Debris will continue to - Selectively remove debris RM .62 over jam and sediment, accumulate. Channel will to allow fish passage. forming anadromous likely divert or jam will - Stabilize large woody barrier. fail, releasing accumulated debris. sediment. 36 0304 7 Habitat Water turbid; oily sheen Water quality will continue - Educate residents about RM .80 and odor present. Storm to decline as runoff and how to maintain water quality. drains empty directly into waste enter stream. - Mark storm drains with stream. "Dump no oil" signs. - Emphasize recycling of oil. 37 0304A 7 Hydrology 3102 Existing forested wetland Additional storage could be Construct a proportional weir RM 1.30 provides detention for utilized by constructing and berm at wetland outlet. Trib. 0304A and 0304 in berm and weir at outlet. Project could be used instead heavily developed area. This could be done to atten- of Project 3107 to rpeserve the uate increased peak flows #1 rated wetland (where project as upstream area develops. would be built). P: LC.APC C-7 Trib. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proi. Conditions and Problems Conditions and Problems Recommendations 33 0304A 13 Hydrology 3115 Runoff generated on top of Flooding will continue as - Construct detention pond RM .40 bluffs on southwest side long as land use remains the at top of bluffs. of Cedar River is causing same on top of bluffs or - Tightline drainage down severe bank erosion, until mitigating measures bluffs, then channelize it flooding and debris flows are taken. Runoff origin- to an existing ditch onto several residences ates from highly compacted alongside SR 169. of valley floor. pastureland on uplands. - Prevent similar problems elsewhere with land use regulations, including provisions for preservation of vegetation buffers near tops of cliffs. 39 0305 10 Geology Extensive bank erosion, Susceptible to increases Attenuate high flows. partly due to subsurface with increasing storm flow. clay layer and landslide topography. 40 0305 10 Geology Local severe bank Problem will continue. Existing rock-filled RM 1.10 erosion. gabions are deflecting flow. 41 0305 10 Geology Extensive channel down- Continued erosion. Attenuate high flows with RM 2.10- cutting and bank erosion. adequate R/D. (R/D 1.75 currently exists.) 42 0305 10 Geology Several gullies and also- Erosion will continue. Tightline culverts. RM 2.15- ciated landslides due to 1.75 daylight culverts on steep slopes adjacent to chan- nels. P: LC.APC C-3 Trib. & Collect. Existing Anticipated Itcm River Mile Point Category Prop. Proi. Conditions and Problems Conditions and Problems Recommendations 43 0305 10 Habitat Madsen Creek in ditch along Potential for fuel entry in- Acquire 30' easement away RM .20 SE Jones Rd. Heavy silt; to creek. Further decreases from roadside. Construct road runoff; water quality in water quality can be ex- new stream channel. adversely affected. pected. 44 0305 10 IIabitat Creek in ditch along south Further decreases in water Acquire 30' easement away RM .35 side of SR 169. Heavy quality can be expected. from roadside. Construct inputs of oils, anti- Potential for autos to enter new stream channel. freezes, heavy metals, channel. Lack of habitat. organic pollutants likely. Sand, silt from roadside (of SR 169) enters also. 45 0305 RM .00- 10 Hydrology 3105 Section of Trib. 0305, Flooding will continue. Construct and enhance 2200' of .40 RM .00-.40 is experiencing (See Appendix A, Project channel through undeveloped extensive flooding. 3105.) King County Park Land. 46 0305 10 Habitat Channelized along dri- Further siltation, water Acquire easement; move RM .50 veway; lacks habitat quality degradation can be creek from driveway diversity. Driveway scdi- anticipated. Lack of habitat 10-15'. Add meanders and ments enter channel, and precludes optimum salmonid habitat structures to oil placed on driveway use. increase diversity. enters stream: 47 0305 10 Habitat Channelized tributary Little salmonid use Add structures to increase RM .65 lacks habitat diversity, anticipated. Spawning and diversity in stream. cover for salmonids. rearing success limited Manually clean. gravels by Gravels compacted. (unless reach is restored). churning them. P: LC.APC C-9 Trib. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proi. Conditions and Problems Conditions and Problems Recommendations 44 0305 10 Habitat Good spawning riffles occur Increased flows may cause Control flows into system RM .90 here. 1/2-3" gravels, few gravel bar movement. from developed areas fines, not compact. High Suitable gravels may be upstream. If necessary, flows are moving material, transported downstream to add bed controls to hold however. unusable areas for spawning gravels or "vee" struc- salmonids• tures to recruit them. 49 0305 10 Habitat Severe bank cutting and Further erosion/scouring can Control high flows by RM .95 erosion occurs here. Bed be expected. Channel increasing upper basin R/D scouring evident. Reach deterioration will continue. facilities, lowering subject to high, rapid Flows appear to be generated discharge rates to stream. flows. at developments. 50 0305 10 Habitat Much woody debris Debris jams will occur with Control upstream flows RM 1.20 movement and numerous greater frequency as flows with greater R/D volume, debris jams. Reach is increase. Sediments will lower discharge rates. subject to high, rapid build up and channel will Selectively remove debris. flows. divert. 51 0305 10 Habitat Channel erosion, bank Further channel deteriora- - Increase R/D capacity. RM 1.70 failures, downcutting oc- tion may be expected. Silt, - Decrease discharge rates. curring. Reach subject to sand transport to mainstem high, rapid flows. will increase. 52 0306 10 Geology Failure of manhole during Not applicable. Repair manhole. RM .40 11/36 storm has resulted in gully erosion. P: LC.APC C-10 Trib. K Collect. Existing Anticipated Item River Mile Point Category Prop. Proi. Conditions and Problems Conditions and Problems Recommendations 53 0306 10 Geology Channel downcutting, bank Erosion will increase. Clay Further increase in runoff RM .20 erosion and several layer in valley makes area should be attenuated; this landslides, due both from sensitive to landslides. is a sensitive channel. increased storm flows and development along edge. 54 0306 10 Geology Undersized culvert in arti- Possible fill failure: Lake Enlarge the corregated RM .30 ficial fill in golf course ponded behind culvert in metal pipe and/or threatens to build lake and in 1931 and threatened construct adequate trash possibly overtop bank. the fill. rack. Breach flood possible. 55 0306 11 habitat Channel subject to high, Further channel damage can Increase R/D capacity, RM .25 damaging flows. Erosion be expected. Sediment decrease discharge rate. evident. transport downstream will continue. 56 0306 10 Geology Downcutting, bank erosion Will continue or increase in Attenuate storm flows. RM .30-.45 and landslides. future. 57 0306 hydrology 3118 Trib. 0306 connects with Problem will worsen as - Replace existing pipes RM .30 large tributary at manhole development upstream with larger diameter pipes here. Debris from 0306 continues. (if downstream analysis clogs this manhole, causing allows for increased flows). severe erosion of Fairwood - Install new inlet struc- Golf Course. tures with trash racks. 58 0306A 11 Ilydrology 3122 Existing small ponds on Area upstream is developing - Acquire easements for ponds RM 1.30 0306A are overtopped and quickly, thus worsening the and additional area around ponds receive considerable silt problem. and construct detention pond. during high flows. The - Location is ideal for addressomg ponds are located on peak flows before they reach Fairwood Golf Course. the sensitive Cedar Reiver bluffs. 11: 1,C.APC C-11 Trib. & Collect. Existing Anticipated Item River Mile Point Categyory Prop. Proi. Conditions and Problems Conditions and Problems Recommendations 59 0306A 11 Habitat Some usable habitat exists Further habitat deterioration - Increase R/D capacities. RM .25 for resident salmonids. likely. Channel erosion will - Decrease discharge rates. Water quality is poor. increase. - Encourage use of 2-cell Channel subject to high detention ponds, swales. flows. - Prohibit filling of existing wetlands, ponds in upper basin. 60 0307 12 Geology Extensive bank erosion at Increased erosion will - Mitigate development- RM .10-.40 all meanders and obstruc- result with increased flows. related high flows. tions (trees, cars) due - Provide adequate R/D. to increased flows from development. 61 0307 12 Geology Stream eroding toes of Increasing erosion with - Mitigate development RM .10-.60 slopes resulting in increasing flows. related high flows. landslide failures. - Provide adequate R/D. 62 0307 12 IIabitat Stream channel pushed to Erosion will worsen as - Increase R/D capacity at RM .30 one side of ravine for stream flows increase. all delivery points. roadway. High energy May threaten road bank at - Reduce release rate below system. Much bank cutting, toe of slope. channel scour level. sediment transport, debris movement. 63 0307 13 Hydrology Area on top of bluffs near Infiltration sites should Construct retention faci- RM .60 Trib. 0307 has excellent be used whenever possible. lities for new develop- infiltrative capacity. These would provide ground- ments in area at these sites. water recharge. P: LC.APC C-12 Trib. R Collect. Existing Anticipated Item River Mile Point Category Prop. Proi. Conditions and Problems Conditions and Problems Recommendations 64 0309 15 Habitat Subject to heavy, rapid Erosion, deposition will - Control storm flows RM .10 flows. Channel erosion, increase. Sediments will upstream. deposition bars migration. migrate downstream, creating - Control volume and discharge a water quality problem. rates. 65 0310 15 Geology Sedimentation upstream from Continued sedimentation. - See "Hydrologic and hydraulic RM .60 culvert due to debris and characteristics" section in undersized culvert. New this report. corregated metal pipe con- tinues to pass water through. 66 0310 15 Geology Severe erosion below Continued erosion and - Install energy dissipator RM .05 culvert, severe sedimen- sedimentation. below corregated metal pipe. tation in residence yard. - Excavate channel through yard where original channel was located. 67 0310 15 Geology Road drainage forming gully Continued erosion. Reroute drainage. Refer problem RM 1.50 adjacent to road; road bed to Roads Maintenance. in danger. 68 0310 15 Habitat 3120 Corregated metal pipe is Problem will continue. Reinstall corregated metal RM .25 anadromous barrier. pipe at or below bed level. P: L,C.APC C-13 Trib. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proj. Conditions and Problems Conditions and Problems Recommendations 69 0310 15 1yydrology 3120 Existing channel draining Frequency and severity of Construct detention pond RM .40 off bluffs on north side problem will worsen as on upstream side of Jones of Cedar River, causing development on bluffs Rd. to trap sediments, and flooding of residences and increases. enhance 1,000' of creek debris flows onto .Tones Rd. from Jones Rd. to Cedar during peak flows. River. 70 0310 15 Habitat Corregated metal pipe Problems will continue and Remove new and old pipes; RM .60 outlet approximately worsen as outfall velocities replace at lower level 9' above bed level. will scour bed and banks. with oversized pipe with Complete barrier to fish. Upstream has recent (11/86) trash rack. Old culverts at bed level deposition up to 4' deep. are plugged. 71 0311 13 Geology Gully erosion in drainage Continued accelerated ero- If possible, enlarge R/D RM 1.70 Swale due to outflow of sion. prior to its outlet in the wetland that partly seems wetland. to act as an R/D facility. 72 0314A 16 IIydrology 3117 Severe erosion, flooding, Problem will be aggravated - Tightline drainage between RM .20 damage to County and as area above develops. detention ponds in gravel pit. private roads from - Construct detention pond increased runoff from next to Jones Rd. to trap gravel pit operations on sediments. hillside. - Construct channel from Jones Rd. to Cedar River. 73 0314A/ 16 Geology Inadequate R/D, plugged Not applicable. See hydrology comment 0314B culvert caused by exten- above. RM .10-.40 sive channel and bank erosion and landslides. Water has cut a new channel. P: LC.APC C-14 Trib. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proj. Conditions and Problems Conditions and Problems Recommendations 74 0317 Hydrology 3111 Francis Lake is only Trib. 0317 flows through - Construct proportional RM 1.60 hydraulic control for steep area downstream of weir at outlet. Trib. 0317. lake. If area around Francis - Enhance 1,100' from Lake develops, increased Francis Lake to SE 184th St. peak flows could cause severe damage to Trib. 0317 in the steep region. 75 0320 Hydrology 3114 Existing forested wetland If surrounding area urban- Construct containment berm RM 2040 with large amount of un- izes, this would be a good and control structure at utilized storage. Wetland site to attenuate peak outlet of wetland (if bio- currently detains flows on flowso logical analysis permits). Trib. 0320. 76 0318 19 Habitat Salmonid parr in many Decrease in water quality Establish and maintain RM .10 pools. Large pools up to with increasing develop- adequate buffers, 100' 1.75' deep. Some deposi- ment. Loss of habitat. from ordinary high-water tion in pools, behind Decrease in fish use. mark or 25' from top fo obstructions. slope break, whichever is greater. 77 03,92 19 Habitat Salmonid use apparent from System is mostly in natural - Maintain adequate stream RM .35 carcasses. Sockeye, condition. As development corridor buffers. Chinook spawners. Some increases, higher flows and - Reduce discharge rates to sedimentation occurring. worse water quality can be pre-development levels. expected. Prevent clearing, grading within buffers. P: LC.APC C-15 Trib. R Collect. Existing Anticipated Item River Mile Point Category Prop. Proi. Conditions and Problems Conditions and Problems Recommendations 78 0328 19 Geology Medium-density landslides None. Limit development in the RM .SO and high-density hank basin. erosion occurring due to natural causes. This indi- cates channel and valley sensitive to effects of development. (Sensitivity due to clay laver. Basin hosts some of best fish habitat in upper reaches.) 79 032.9 19 IIabitat Significant salmonid use Sedimentation from upstream Maintain leave strips RM .70 throughout. Sockeye reach possible. Adjacent adjacent to stream at spawners, carcasses present. development will likely least 100' from ordinary Coho, steelhead parr in reduce diversity and quality high-water mark. Restrict pools. Excellent habitat of habitat. use/development within this for spawning and rearing streamside management zone. (a redd site). Much diversity -- most exemplary in basin. Channelized reach. Uniform May cause thermal problems Restore stream habitat RO 0323 19 Habitat channel, no habitat diver- as water temperatures rise. throughout: add structure, RM 1.10 sity. Heavy sand deposition. No useful habitat. diversity, bank vegetation, 1.40 Little overhead canopy or and canopy. Cost should be bank vegetation. borne by party(ies) who channelized this reach. 31 0323 19 Hydrology 3112 Lake Peterson is small, Lake provides good peak flow Replace weir at outlet RM 1.40 open-water wetland with a attenuation and will become with a higher weir in weir at outlet. more important as upstream order to gain additional tributary area develops. storage. P: LC.APC C-16 EXHIBIT F SENSITIVE AREAS FOLIO 11 • �t-- 1b { - .' ! Mercer Slough West r T * t._ A_ 1 Lake F . . East 'sam mamish .. W -_t- - r. FAercer�Slarxf c Coal Creek Lake - ' - , : is >��as• , • ' lr 7� +4 ice:` t—�l / u '�1..-; :, r ` Iw 47; _ Wiax cay.it \ _'fib .14 20b- �23ti 21b i 1. ♦ ' 9 i.. ,i 1 - 1 1 i - 22b i - 1 4 ' i4b � Lowe(Cedar_: r�'''{' li,fx `�\- -[' �� ,_.t. ` ' 1 � 7 ; \•� { j�I r �i t 4 A. L.., .•'' fly ,I' ...�..J � ; �' r j ♦ � _.__ ,[ Wetlands D uwa rn,s h ,nctudetl in the �T those with he Wetlands I iu ventory, The -- s design ated 'a'• have Open Water 2 13. s;te by a variety of Z- `8!{'-' :signated "b"are maP- 9 .t4. 1s 1 •i and Wildlife Service tttttt�attttt� Basin Boundaries i:' - , 'v r.•n lury,but their iota- ,, 5 is 1t2 cla verified. ��. Sub-basin Boundaries ;.-6 `11 in the numbering se- - vidnal drainage basins_ I � - I ' L 1 ! 11, A -yr yam e A /•T i, rt i r� r 1,,,• i AL - 1; LFj,t r 1 1 F 11. ,ems 4" 'ci � /'i.?J F� �'-�-}• .. / ;�} ��.' .1 -r� . ~ ..( I .. F,;-- ,\ 1 �.• 1 L cl AL -•- �,..,: "+ --_- ���_ .�..�; rye-•.�. � _ \� ,l VAI - f Fli d, l l\ /;/• ' _ `rr-I:' ,J �s]`�",l- �t.� +e. �� .i T714 1.-1 1��_''AS-1+ fQ -1 1 ; DY - � t � 1 / 1': t 1 � ��".}}•.�y �I_ � 1 'ice. � �,, ,,,�j �- . or plains extend be- Class 1 Dt1W.1fMS1l laps. Flood in- streams and 100- H--�-�-� Class 2(with salmonids) t always show the • headwaters of streams. year Floodplains Class (perennial;salmonid use undetermined) e c e • • Class ," N Unclassified " 1 1'Floodplalfu ; 12 r.. i ' }� IN �yy i ' �✓' ,�'�` '�.�'9'� Alt: ,�!'�� �!�' � ,N� -��r,._��_� JO oil Aw All- Sp d7f�Y/7 j I ►� �Y�S'/ �q\ t 4A• Syr/.� v Vy� �°�s Ali s � /ram fnncra�► �._A II trfM • Mull G } per Ts I— .;, ft'(�l �rta ' AW .�9 tit �1 t111d � " ��•:� Oak ,pi� �� ,, �#moo ,•�� '� � / .. � �—��.t �,�t 9�i�; .Ake •�• �Q ,e,� 1.°'"'�' ; �� t �� � RT �Mll� •3�Wo ■ I w ►�ia� r� �� q{I ..::emu � � ��.t� • r� MIN Fall Willy i %��� •'' r.fit �+� as+��� �f sew '•�4 � �POW NOWd' / \vs c c_ jai _a On Out c pq ���_ 0.6 n 7 b Y N p _ - n e U. 1` { Q� .y e•.i+ ' j y- Y� f p N�N W G .�.x �•� - �r al'-.♦ }ti_,�~ r,.: ,l�',� i",t.•1"" ��317y 1� � ram',% (K f+i a CA , � `� y :,,) � i� •' f- tr � � P� ,y, }�+(lt*�1 �; I �' ' 1., �+ ,� a � �� r�✓,' if� " „� lam'{ ',r' SE Iti JI Cir s., • i xL' ' ' �*. -; 's• . :�'S '�•� �r,/ r-�--��,. ) �•�'� �.mow'r 7 �: -�i .r.^^.•.'{ �' �•/ S �1�. _.:4 � (V/ .ram •`�J 'ry t � f �• "•"• � is t'ti f. ".r ,: __ 'f ` t �,"Y+.� �.t'�, � ,.. �Q• ��, ': , err - '�11: ,;" �--:�-'-, , �,4 ,-., �_ ''�\�"� . � r :r /�t '``1 ��-. .�..• •��' 1 }. ��1.c� f (J �t � i "-� T'T ..fir' T{\� �rr�,f ...1.. i'-,y✓f��' � r-... !'c:� J ` %�,'/'��%s t 1 fit_. / / L i N � � — --- I�i�►►..���. _ 111!", �r -,..— ^�^�` ,.J � 1,' ��1 /,/1.•' J/ r �'N•.4 r°- � _ � •• --�; f •� I •. l ! ...�� ��} ";ter.- ;. r '�� {_-� `P•�41 f' .�5: t;• '+ ., t .1 f�rY r�'+ / f"/L)o + ,j , ~ ! r� �! r , . ( � .- �t' ;,--- ... M. 'fir 'n`�r•�'�' `f' �r ��_-. f ■1l won �j�'wwsseef INS a�. i xa , 1 � � fill a 6 • �q ills MAR Wits NO M �� �� �, °1RON, 11lC R` � ��' . �► -tie Aq az ��� �IIsi1�i�►` YIII� u IlL+lil�a.�►.,.i� :� �. EXHIBIT G WETLAND INVENTORY MAP EXHIBIT H DRAINAGE COMPLAINTS FROM:KING CO. DEPT.NR WLRD TO: 20G2518782 S20G JUL 9, 1997 10:45AM P.02 PROBLEM TYPE OF NEW ^aMPLN Ty TH OR 4UMBER PE ADDRESS PROBLEM COMMENTS :S[cc:e ecc c=a■■ cL fffcc2eaffco=ee cs zz[fcL=z fizSOe[fccsaaa[fzDe u[sc�zeafs Czf[c 75-0135 C 13921 SE 136TH PL FLOG SWAMP/SE 136TH PL/HIDEWAY HTS 656J2 81-0197 C 13832 SE 131ST ST/REN T DRNG BLKED 656J2 82-0341 C 14005 SE 133RD ST FLOG 656J2 82.0386 C 12808 138TH AVE SE DRNG & FLOG 656J2 82-0491 C 14009 SE 128TK ST FLOG MAPLEWOOD HTS 656J2 82 20 55 C 16935 116TH AVE SE DVR 9 SE 132ND/144TH AVE SE 656J2 83-0353 C 13224 144TH AVE SE FLOG 656J2 4.0221 C 140XX SE 132ND ST DVR FLOG 656J2 85-1 C 14100 SE 132ND ST DRNG SEE 84-1005/TO ROADS 656J2 86-OSD9 C 14011 SE 132ND ST DRNG SURFACE WATER 656J2 86-01D9 C SEE YANK STUDY 656J2 86-0256 F 656J2 86-0256 C 86-0256 S1 COMMITTED DATEs1ST QTR 1989. 656J2 656 SE DRNG SYSTEM SILTED J2 86-03A4 C 138TH AVE 656J2 86.03A4 E PROB CRTD. b56J2 86-0739 C 13323 146TH AVE SE FLOG WATER FROM SCHOOL 87.0255 C 14639 SE 132ND ST FLOG STANDING WATER & MUD 656J2 87.0328 C 13323 146TH AVE SE DRNG CO DIVERTED DRNG ONTO PROPERTY 656J2 87-0405 C 13025 138TH AVE SE FLOG SEE 87-0463 OVER STREET 656J2 87-0445 C 13837 SE 128TH ST FLOG FILLING OF LOT 656J2 87r OGL5 ER 13837 SE 128TH ST FLOG SEE 86.03A4 PENTON, 87-0707 656J2 656J2 87-0463 X 13025 138TH AVE SE FLOG ON 138TH AVE SE 656J2 88� 0280 C 14106 SE 135TH ST DRNG STRORM DRAIN FAILURE -00 6 C 14003 SE 132ND ST DEBRIS DEER[ ON RD TO DET POND 656J2 89-0113 C 13852 SE 128TH.AVE DRNG DRAINAGE OF NEIGHBORS 656J2 FILL/ROAD CONST 84-0200 C 13120 138TH AVE SE SETTLING SINK HOLE IN YARD 656J2 89.0461 S2 14011 SE 132ND ST FLDG/DVR SEE-86-0256 YAHN PH I 656J2 89 0472 X 14105 SE 133RD ST INQUIRY STATUS OF STUDY(YAHN STUDY) 656J2 89.0636 X 14103 SE 132ND ST DRNG YAHN STUDY COMPLAINTS 656J2 90-02D9 C 14639 SE 132NO ST FLOG DITCH OVERFLOW/STORM EVENT 656J2 90-0 883 C 14105 SE 133R0 ST DRNG FLOODING IN NBRHD b56J2 90-0512 C 13600 138TH AVE SE DRNG CROSS PIPE ERODING RAVINE 656J2 90.0556 C 13323 146TH AVE SE DRNG DITCH ENDS/DIVERTED WATER 656J2 90=0556 ER 13323 146TH AVE SE DRNG XPIPE AND POND/DITCH ENDS 656J2 90.0804 X 14105 SE 133RD ST FLOG COMPLETION OF STUDY 6S6J2 ,90-1511 X 14105 SE 133RD ST FLOG CAPACITY OF PLAT DRNG 656J2 91-0081 X 14105 S 133RD ST DRNG CCF#191-32/YAHN STUDY/FLOODED 656J2 YARD 91-0081 SR 14105 S 133RD ST DRNG PUGET COLONY HOMES 656J2 91-0098 X 14105 SE 133RD ST DRNG CCFfSWM0124/DEVELOPEMENT 656J2 91• 8 SR 14105 SE 133RD ST DRNG CCF#SI.M0124 PUCE! COLONY HOMES 656J2 91-0246 C 14013 SE 133RD ST DRNG PLUGGED b56J2 91-0246 SR 14013 SE 133RD ST DRNG PLUGGED PUGET COLONY HOMES 656J2 21-0315 C 14011 SE 132ND FLOG DIVERSION/CULVERT OVERFLOW 656J2 91.0636 X 14105 SE 133RD ST FLOG CCF#491-32/PLAT DRAINAGE 656J2 91-0636 NDA 14105 SE 133RD ST FLOG CCF#491-32 NOT NDA PUGET 656J2 COLONY HOMES 0650 X 14105 SE 133RD ST DRNG CCF#S91-2 SAME OLD PROS 656J2 91-0650 NDA 14105 SE 133RD ST DRNG CCF#591-2 NOT NDA PUGET b56J2 COLONY HOMES FROM:KING CO. DEPT.NR WLRD TO: 20G2518782 S20G JUL 9, 1997 10:46AM P.03 91-0682 CL 14105 SE 133RD ST FLOG CCF# 591.2 DUE JULY 656J2 91 071Z X 14103 SE 132ND ST DRNC CCF# SUM 05ZO MANY COMP 656J2 � .0 712 NDA 14103 SE 132MD ST DRNG CCFN SWM 05ZO NOT WDA PUGET 656J2 COLONY HOME HOOD FLOODING 656J2 DRAINAGE NEIGHBOR 91-0715 C 14105 SE 133RD ST 656J2 �1 0T15 SR 14105 SE 133RD ST DRAINAGE PUGET COLONY HOMES 656J2 91-00723 X 14105 SE 133PD ST DRAINAGE CCF# 591-3T 91-0723 SR 14105 SE 133RD ST DRAINAGE CCF# 591-37 PUGET COLONY HOMES 656J2 �91-0732 C 14024 SE 133RD ST DRAINAGE /LAMB (CLAIM) 91.0732 SR 14024 SE 133RD ST DRAINAGE /LAMB (CLAIM) NOT NDAP 656J2 gi-Q739 SR 14103 SE 132ND ST DRNG/FLO CCF# SUM-06JO NOT NDAP 656J2 ,91.0777 X 14103 SE 132WD ST FLOODING CCF# S91-34 656JZ _41-Q NDA 14103 SE 132ND ST FLOODING CCF# 591-39 NOT NDA PUGET 656J2 COLONY 91.0812 C 14639 SE 132WD ST DRAINAGE 656J2 91-0868 x 14010 SE 134TH ST DRAINAGE CCF# SUM0279/PUGET COLONY 656JZ Q1 0868 SR 14010 SE 134TH $T DRAINAGE CCF# SWM0279 NOT MDAP 91-p888 X 13800 SE 128TN ST FLOWING CCF#FLOODING CCF#SMt 0852?NOTLAND NOA-PUGETEMS 656JZ 91-0888 SR 13800 SE 128TH ST COLONY HONES 91- 46 X 14105 SE 133RD ST DRAINAGE CCFX: 91-0822/GRANTING 656J2 EASEMENTS 91-1214 X 14105 SE 133RD DRAINAGE CCF# SUN 1217/PROJECT SCHEDULE 656J2 93.0179 C 137XX 144TH AVE SE DIVERSON POSS CLEARING VIOLATION 656H2 93.0239 X 14105 SE 133RD ST INQUIRY INFO ONLY 93-1064 C 14400 SE 136TH ST FLOG GROND VACATION DRpINAGEATER UNDER IMPACT FRppOADWAY 656J2 YACATION 656H2 9�5-0_763 C 14010 BE 134TH ST REQUEST g6;12A3 C 140TH SE 132RD -135TH SE CIP REQUEST TO 00 ASSESSMENT OF 656H2 CONVEYANCE 97- 65bJ2 5 C 14105-SE 133RD ST FLOG PUGET COLONY MOVES 656J2 �O55 R 1410S SE 133RD ST FLOG PUGET COLONY HOMES 47-0055 NDA 14105 SE 133RD ST FLOG PUGET COLONY HOMES 656J2 EXHIBIT I KING COUNTY SOIL SURVEY SOIL SURVEY King County Area Washington *4 76% UNITED STATES DEPARTMENT OF AGRICULTURE Soil Conservation Service in cooperation with WASHINGTON AGRICULTURAL EXPERIMENT STATION Issued November 1973 d CM a�a � �• S v' � Y r`_7j •� 1 r1.$_ II �r� s'. . .�0'. 1 :r 'f I:d 1 j ' k..k.3s�.4 :�� � :a ,-,.. #-i _ d�4�Ys f..�-':p' _ �I�.__ Y ;, .� , i 1 1 � �•�• :'O.' 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F � .. :f 'y 1 ��t I V i � /� r ,,:� .. ;: �� s 4 .. �■ _� 11 ti �r � r-- r i >, >t .P�" DES <,d �• /� rj ♦ G' .. ��fp I `iidh ♦ - 'Ali � \ f;♦C c�` "r:/... ..., i,`'' '. y�4 ,J• •��W .• .�+ (�'�;'�`.4 _`'i r.--• I � I Ln MC- - �1. d�. �J J t -�'. I.r e�. �.W • m� •� �JY � �� ',� �2.•. ` �.� (; �1' � • ? s -I 1t�1�• .. •��.�'' +�•�; R�,rj'„ ,,;;���� ♦ 1 � `�i` "'�. J�� ry };�-�� � ,r r�,p. °Q �o I •m E 1 f •jt1.••r. •; t •� ' �LRi' fa,� '� Its��,, �. � �r>ti y' � •. `f^' '� ;,.. ¢ ¢ 1T•�y FR 4 i� .•gyp..„ i 7 �• •;Lti E • t T, t` r • •fi �iJ ',71' • '.All•,. rL• ���;': S? 1J^: 11 �' +,'\ L < I '. � :i • I r. • •.•.•••• . , ' •'• • ../ , � .;a �j, ,`�}..},; ;� � .�� � ,��,�r f.•• '�. 3 ■ .f •, y.R. rlJj •4 lE ]ti1;.F,/• \, ,e � I' 1 • j _I �• L ttYr 1 i 1 ill • •.�w�..; r r r j ' 'Q1 .... �,, GUIDE TO MAPPING UNITS For a full description of a mapping unit, read both the description of the mapping unit and that of the soil series to which the mapping unit belongs. See table 6, page 70, for descriptions of woodland groups. Other information is given in tables as follows: Acreage and extent, table 1, page 9. Town and country planning, table 4, page 57. Engineering uses of the soils, tables 2 and 3, Recreational uses, table 5, page 64. pages 36 through 55. Estimated yields, table 7, page 79. Woodland Described Capability unlit group Map on symbol Mapping unit page Symbol Page Symbol AgB Alderwood gravelly sandy loam, 0 to 6 percent slopes---------- 10 IVe-2 76 3d2 AgC Alderwood gravelly sandy loam, 6 to 15 percent slopes--------- 8 IVe-2 76 3dl AgD Alderwood gravelly sandy loam, 15 to 30 percent slopes-------- 10 VIe-2 78 3dl AkF Alderwood and Kitsap soils, very steep------------------------ 10 VIIe-1 78 2dl AmB Arents, Alderwood material, 0 to 6 percent slopes 1/---------- 10 IVe-2 76 3d2 AmC Arents, Alderwood material, 6 to 15 percent slopes 1/--------- 10 IVe-2 76 3d2 An Arents, Everett material 1/-------------- 11 IVs-1 77 3f3 BeC Beausite gravelly sandy loam, 6 to 15 percent slopes---------- 11 IVe-2 76 3d2 BeD Beausite gravelly sandy loam, 15 to 30 percent slopes--------- 12 VIe-2 78 3dl BeF Beausite gravelly sandy loam, 40 to 75 percent slopes--------- 12 VIIe-1 78 3dl Bh Bellingham silt loam------------------------------------------ 12 IIIw-2 76 3w2 Br Briscot silt loam--------------------------------------------- 13 IIw-2 75 awl Bu Buckley silt loam--------------------------------------------- 13 IIIw-2 76 4wl Cb Coastal beaches----------------------------------------------- 14 VIIIw-1 78 --- Ea Earlmont silt loam-------------------------------------------- 14 IIw-2 75 3w2 Ed Edgewick fine sandy loam-------------------------------------- 15 IIIw-1 75 2ol EvB Everett gravelly sandy loam, 0 to 5 percent slopes------------ 15 IVs-1 77 3f3 EvC Everett gravelly sandy loam, 5 to 15 percent slopes----------- 16 VIs-1 78 3f3 EvD Everett gravelly sandy loam, 15 to 30 percent slopes---------- 16 Vle-1 77 3f2 EwCEverett-Alderwood gravelly sandy loans, 6 to 15 percent slopes------------------------------------------------------ 16 VIs-1 78 3f3 InA Indianola loamy fine sand, 0 to 4 percent slopes-------------- 17 IVs-2 77 4s3 InC Indianola loamy fine sand, 4 to 15 percent slopes------------- 16 IVs-2 77 4s3 Indianola loamy fine sand, 15 to 30 percent slopes------------ 17 VIe-1 76 4s2 s Kitsap silt loam, 2 to 8 percent slopes----------------------- 17 IIIe-1 75 2d2 ..pC Kitsap silt loam, 8 to 15 percent slopes---------------------- 18 IVe-1 76 7d2 KpD Kitsap silt loam, 15 to 30 percent slopes--------------------- 18 VIe-2 78 2dl KsC Klaus gravelly loamy sand, 6 to 15 percent slopes------------- 18 VIs-1 78 3fl Ma Mixed alluvial land------------------------------------------- 18 VIw-2 78 2ol NeC Neilton very gravelly loamy sand, 2 to 15 percent slopes------ 19 VIs-1 78 3f3 Ng Newberg silt loam--------------------------------------------- 19 IIw-1 74 2ol Nk Nooksack silt loam-------------------------------------------- 20 IIw-1 74 2ol No Norma sandy loam---------------------------------------------- 20 IIIw-3 76 3w2 Or Orcas peat---------------------------------------------------- 21 VIIIw-1 78 --- Os Oridia silt loam---------------------------------------------- 21 IIw-2 75 3wl OvC Ovall gravelly loam, 0 to 15 percent slopes------------------- 22 IVe-2 76 3dl OvD Ovall gravelly loam, 15 to 2S percent slopes------------------ 23 VIe-2 78 3d1 OvF Ovall gravelly loam, 40 to 7S percent slopes------------------ 23 VIIe-1 78 3dl Pc Pilchuck loamy fine sand-------------------------------------- 23 VIw-1 78 2sl Pk Pilchuck fine sandy loam-------------------------------------- 23 IVw-1 76 2sl Pu Puget silty clay loam----------------------------------------- 24 IIIw-2 76 3w2 Py Puyallup fine sandy loam------=------------------------------- 24 IIw-1 74 2ol RaC Ragnar fine sandy loam, 6 to 15 percent slopes---------------- 2S IVe-3 77 4sl RaD Ragnar fine sandy loam, 15 to 25 percent slopes--------------- 26 VIe-2 78 4sl RdC Ragnar-Indianola association, sloping: I/---------------------- 26 Ragnar soil--------------------------------------------- -- IVe-3 77 4sl Indianola soil------------------------------------------- -- IVs-2 77 4s3 RdE Ragnar-Indianola association, moderately steep: 1/------------ 26 -------- -- Ragnar soil--------------------------------------------- -- VIe-2 78 4sl Indianola soil------------------------------------------- -- VIe-1 77 4s2 U. S. GOVERNMENT PRINTING OFFICE:1973 0-468-366 GUIDE TO MAPPING UNITS--Continued Woodland Described Capability unit group Map on mbol Mapping unit page Symbol Page Symbol ------ 26 IIIw-1 75 3wl Re Renton silt loam------------------------------"-""--_---- 27 VIIIw-1 78 --- Rh Riverwash--------------------------------------------- Sa Salal silt loam---------------------------- ----------- 27 IIw-1 74 2ol Sh Sammamish silt loam----------------------------------------- 27 IIw-2 75 28 IIw-3 75 --- Sk Seattle muck------------------------------------------------ 29 IIw-3 75 --- Sm Shalcar muck------------------------------------------------ 29 IIw-1 74 Sn Si silt loam------------------------------------------------ 3 w2 3 So Snohomish silt loam------------------------- -------- IIw-2 .75 3w2 Sr Snohomish silt loam, thick surface variant------------------ 31 IIw-2 75 3w2 Su Sultan silt loam----------------------- --------- 31 IIw-1 74 3w1 32 IIw-3 75 --- Tu Tukwila muck------------------------------------ 33 ------- -------- -- --- Ur Urban land----------------------- -------------------- Wo Woodinville silt loam--------------------------- ------- 33 IIw-2 75 3w2 1/ -the composition of these units is more variable than that of the others in the Area, but it has been controlled well enough to interpret for the expected use of the soils. IV. RETENTION/DETENTION ANALYSIS AND DESIGN 4.0 RETENTION/DETENTION ANALYSIS AND DESIGN A. EXISTING SITE HYDROLOGY The 8.4-acre site consists primarily of brush and tree cover, with the exception of a paved area fronting N.E. 4th Street. This paved area consists of 0.57 acre and contains no significant drainage features. A small portion of the eastern half of the site sheetflows to existing wetlands. The majority of the site is very flat and flows from northeast to southwest toward the intersection of Duvall Avenue N.E. and N.E. 4th Street. Times of concentrations were calculated based on the sheetflow and shallow flow tendencies of the existing site. Curve numbers used in the calculations are determined based on the King County Soil Survey maps showing the on-site soil to be Everett gravelly, sandy loam, a Group "B" soil with a curve number of 72. This is based on a young second-growth wood and forest condition. Please refer to the existing conditions exhibit later in this section of the report for further information concerning existing conditions of the site. B. DEVELOPED SITE HYDROLOGY Storm drainage runoff from all paved areas and building areas of the site will be collected in a tightline conveyance system located beneath the parking lot which conveys all the storm drainage to a detention pond located in the northeast comer of the site. Times of concentration were calculated based on sheetflow across landscaped areas and paved areas and conduit flow in the tightline conveyance system. The total developed area of the site is 7.4 acres, including the detention pond. The existing wetland in the southeast corner of the site will be enlarged and enhanced to compensate for the filling of the smaller wetland located in the center of the east section of the site. Curve numbers are again based on the soil conditions; a curve number of 80 for the proposed landscaped areas and 98 for impervious areas. C. HYDROLOGIC ANALYSIS ; The storm drainage conveyance system for the project is designed based on a hydrograph method using the 25-year/24-hour design storm. The proposed conveyance system is designed to work as a gravity system requiring no additional head to convey the design flows. The proposed detention pond is a 3-cell pond located in the northeast corner of the site which will limit outflows of the 2-year, 5-year, 10-year, and 100-year/24-hour storms to one-half the 2-year, 5-year, 10-year, and 100-year existing condition peak flows. A minimum 10 percent volume increase for the 2-year design storm and 30 percent volume increase for the 100-year design storm have been included in the detention pond. The pond is designed using the Santa Barbara Urban Hydrograph method for calculating peak flows and volumes. Hydrographs were computer-generated using Waterworks software. The computer output is contained in this section of the report. 6116.011 [KL/sm] D. RETENTION/DETENTION SYSTEM The wet/detention pond located in the northeast corner of the site will act dually as a water quality and detention system. A 3-cell wet pond will provide the necessary water quality treatment required for this project. The volume of the wet pond required has been doubled to eliminate the need of a biofiltration swale preceding the pond. The wet pond portion of the detention pond will be 4 feet deep, with the lowest foot provided for sediment storage. Detention will be provided in the 3 feet above the wet pond surface. Retaining walls extend from the wet pond surface elevation to the top of the pond. The control structure for the detention pond will be contained in a Type 2 catch basin located off the southwest corner of the pond. This catch basin will contain a riser with an orifice and weirs to limit post-developed flows to pre-developed conditions as described in part "C" above. The controlled flows exiting this structure will flow south and be discharged into the existing conveyance system in N.E. 4th Street. 6116.011 [KL/sm] TaT S A4ak�5� 7 3J o-7 s I-z- s 9� 3 4 �4 /�IO�TZ v/ov s coo a —ery ava CCI CI N r N N � z;rve s<7a at 4t = 5.34 7 A— eel A ei ��PC2✓ra.� �� (vNc �A^�lfe�v) � ' &. )O �q� Gti `tom pL�12vr6U S 8v -� 19�f5 r/1f 3oD 14W SiJWeel- FcAL.J M + too e-F �E�i4 /LZdtv(2�.�-tg7tJ�j Fto L.� 2 Y2 2y2 /Z4 p(a -�—Y2 AZ4 lf,-4 5-Y2 /2A lfvz - /D �2 124 c 1DY2 /24 t, f60 Y2 A4- Gob r2 �z� � � t 70 '/.' 1 p i I 54 S6'�d� z� a Tor► Qf -�a�i✓r� OWSL b� So! 18S� ^ $3� —� • 006 2L£ S bn� `�•d j n 9bL� �a coo A A A A N &AtALA ___ M I"M mmm 1- -4 M!A N LS-P "i, ii P File input Hydrograph Storage Discharge LPool Proj : fi11b-DEI ieeeeeeeeeeeeeeeeeeeeeeeeeeeKouting Comparison labieeeeeeeeeeeeeeeeeeeeeeeeeeeel MAICH 1NFLUW SIU UIS PEAK NEHK UU1 "UESCK1PIiDN PEAK; PEAK No. No. 516 UUI HYU 1 /2 LYH/Z4HH DESIGN �.Uy 4Zj UE51GfJ LYK iy(.48 !0.(D`J L YH/24 HK DESIGN 0.28 3.06 DESIGN L/S 397.87 0.28 3 1-0 YK/24 HR DESIGN 10.44 3.79 DESIGN L/S 398. 16 0.43 4 - 100 YR/24 HK DESIGN 0.89 5. 2? DESIGN COMBINE 398.SGO 0.89 G `L YK/24 HR FINAL 0.100 2.48 FINAL COMBINE 396.97 0.08 b 'S 1'K/24 HR FINAL 10.00 3.06 FINAL COMBINE 39?.43 0.09 / 10 YK/L4 HK FINAL 0.00 3.79 FINAL COMBINE 391.88 0.29 8 1100 YK/24 HK FINAL 10.00 S.G ( FINAL CUMBiNE 398.35 0.8'6 y . . ` =as===:saaa=-m=aa�UOneC9s�m�a=c�:osaaa�saax Press any key to exit eeeeeeeeeeeeeeeeeeeeeeeeeeeetee@eeeceeeeeeeeeeeeeeeeeeeeeeeeeee@eeeeeeeeeeeeeeef' Menu: Perform Level pool computations using input table instructions P File input Hydrograph Storage Discharge LPool Proj : B) IB-DEJ Barghausen Engineers iel±Jeeeeeeeeeeeeeebeeeeee Display Level Fool Results eeeeeeeeeeeeeeeeeeeeeeeeel ' Match Inflow Storage Disch Peak Peak Peak Description Peak Peak ID lU Stage Volume Out 1 /2 2YK/24HK DESIGN 0.09 2.48 DES16N LYR 357.48 36538 0.09 S YK/24 HR DESIGN 0.28 3.06 DESIGN 2/S 387.87 42B15 0.28 ` ]TO YW24 HR DESIGN 10.44 3.79 DESIGN L/S 398. ib 41187 0.43 100 YR/24 HR DESIGN 0.8y 8.27 UESIGIV COMBINE 398.5O 51563 i0.8y " ` L YK/24 HR FINAL 2.48 f-INAL. CUMBINE 388.97 3-10y4 10.08 ' S Y 24 HR FINAL 3.06 F 1NhL COMBINE 39'(.43 4bbW 0.09 ' 110 YK/24 H"k FINAL 3.79 FINAL COMBINE 397.88 S565b 0.29 100 YK/24 HR FINAL S.2 7 FINAL COMBINE 3-18.35 SS1 (/ 0.GG Uk E 66666666 aeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee6eeee66eef 5/5/98 10: 51: 31 am Barghausen Engineers page 1 QFC\WALGREENS - RENTON, WA WORKS4 FILE NO. 6116DET.BSN BCE # 6116 BASIN SUMMARY BASIN ID: Dev02 NAME: 2YR/24HR POSTDEVELOPED SBUH METHODOLOGY TOTAL AREA. . . . . . . : 7 .42 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 2 . 00 inches AREA. . : 1. 32 Acres 6. 10 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . . 23 . 82 min 8 . 96 min ABSTRACTION COEFF: 0.20 TcReach - Sheet L: 100. 00 ns: 0. 2400 p2yr: 2 . 00 s: 0. 0100 impTcReach - Sheet L: 100. 00 ns: 0. 0110 p2yr: 2 . 00 s: 0. 0150 impTcReach - Channel L: 856. 00 kc: 42 . 00 s: 0. 0022 PEAK RATE: 2 .48 cfs VOL: 0. 96 Ac-ft TIME: 480 min BASIN ID: Dev05 NAME: 5YR/24HR POSTDEVELOPED SBUH METHODOLOGY TOTAL AREA. . . . . . . : 7 . 42 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 2 . 40 inches AREA. . : 1. 32 Acres 6. 10 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98 . 00 TC. . . . . 23 . 82 min 8. 96 min ABSTRACTION COEFF: 0. 20 TcReach - Sheet L: 100. 00 ns: 0.2400 p2yr: 2 . 00 s: 0. 0100 impTcReach - Sheet L: 100. 00 ns: 0. 0110 p2yr: 2 . 00 s: 0. 0150 impTcReach - Channel L: 856. 00 kc:42 . 00 s: 0. 0022 PEAK RATE: 3 . 06 cfs VOL: 1. 19 Ac-ft TIME: 480 min BASIN ID: Dev10 NAME: 10YR/24HR POSTDEVELOPED SBUH METHODOLOGY TOTAL AREA. . . . . . . : 7.42 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 2 .90 inches AREA. . : 1. 32 Acres 6. 10 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . . 23 . 82 min 8.96 min ABSTRACTION COEFF: 0. 20 TcReach - Sheet L: 100. 00 ns: 0. 2400 p2yr: 2 . 00 s: 0. 0100 impTcReach - Sheet L: 100. 00 ns: 0. 0110 p2yr: 2 . 00 s: 0. 0150 impTcReach - Channel L: 856. 00 kc: 42 . 00 s: 0. 0022 PEAK RATE: 3 .79 cfs VOL: 1. 49 Ac-ft TIME: 480 min 5/5/98 10 : 51: 31 am Barghausen Engineers page 2 QFC\WALGREENS - RENTON, WA WORKS4 FILE NO. 6116DET.BSN BCE # 6116 BASIN SUMMARY BASIN ID: Dev100 NAME: 100YR/24HR POSTDEVELOPED SBUH METHODOLOGY TOTAL AREA. . . . . . . : 7 .42 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 . 90 inches AREA. . : 1. 32 Acres 6. 10 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98 . 00 TC. . . . . 23 . 82 min 8.96 min ABSTRACTION COEFF: 0. 20 TcReach - Sheet L: 100. 00 ns: 0. 2400 p2yr: 2 . 00 s: 0. 0100 impTcReach - Sheet L: 100. 00 ns: 0. 0110 p2yr: 2 . 00 s: 0. 0150 impTcReach - Channel L: 856. 00 kc: 42 . 00 s: 0. 0022 PEAK RATE: 5. 27 cfs VOL: 2 . 08 Ac-ft TIME: 480 min BASIN ID: EX02 NAME: 02YR/24HR PREDEVELOPED SBUH METHODOLOGY TOTAL AREA. . . . . . . : 7 .42 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 2 . 00 inches AREA. . : 6.85 Acres 0. 57 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 72 . 00 98. 00 TC. . . . : 109 . 32 min 109 . 32 min ABSTRACTION COEFF: 0. 20 TcReach - Sheet L: 300. 00 ns: 0. 4000 p2yr: 2 . 00 s: 0. 0060 TcReach - Shallow L: 80. 00 ks: 5. 00 s: 0. 0060 PEAK RATE: 0. 18 cfs VOL: 0. 25 Ac-ft TIME: 960 min BASIN ID: EX05 NAME: 5YR/24HR PREDEVELOPED SBUH METHODOLOGY TOTAL AREA. . . . . . . : 7 . 42 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 2 . 40 inches AREA. . : 6.85 Acres 0.57 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 72 . 00 98. 00 TC. . . . : 109 . 32 min 109 . 32 min ABSTRACTION COEFF: 0. 20 TcReach - Sheet L: 300. 00 ns: 0. 4000 p2yr: 2 . 00 s: 0. 0060 TcReach - Shallow L: 80. 00 ks: 5. 00 s: 0. 0060 PEAK RATE: 0. 28 cfs VOL: 0. 38 Ac-ft TIME: 660 min 5/5/98 10: 51: 31 am Barghausen Engineers page 3 QFC\WALGREENS - RENTON, WA WORKS4 FILE NO. 6116DET.BSN BCE # 6116 BASIN SUMMARY BASIN ID: EX10 NAME: 10YR/24HR PREDEVELOPED SBUH METHODOLOGY TOTAL AREA. . . . . . . : 7. 42 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 2 . 90 inches AREA. . : 6.85 Acres 0. 57 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 72 . 00 98. 00 TC. . . . : 109. 32 min 109 . 32 min ABSTRACTION COEFF: 0. 20 TcReach - Sheet L: 300. 00 ns: 0. 4000 p2yr: 2 . 00 s: 0. 0060 TcReach - Shallow L: 80. 00 ks: 5. 00 s: 0. 0060 PEAK RATE: 0.44 cfs VOL: 0. 55 Ac-ft TIME: 660 min BASIN ID: EX100 NAME: 100YR/24HR PREDEVELOPED SBUH METHODOLOGY TOTAL AREA. . . . . . . : 7.42 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 3 .90 inches AREA. . : 6.85 Acres 0. 57 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 72. 00 98. 00 TC. . . . : 109. 32 min 109. 32 min ABSTRACTION COEFF: 0.20 TcReach - Sheet L: 300. 00 ns: 0. 4000 p2yr: 2 . 00 s: 0. 0060 TcReach - Shallow L: 80. 00 ks: 5. 00 s: 0. 0060 PEAK RATE: 0.89 cfs VOL: 0. 97 Ac-ft TIME: 550 min BASIN ID: TESC NAME: 02YR/24HR EROSION CONTROL SBUH METHODOLOGY TOTAL AREA. . . . . . . : 7.43 Acres BASEFLOWS:• 0. 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 2 . 00 inches AREA. . : 7. 43 Acres 0. 00 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 82 . 00 0. 00 TC. . . . . 10. 00 min 0. 00 min ABSTRACTION COEFF: 0.20 TcReach - Sheet L: 300. 00 ns: 0. 4000 p2yr: 2 . 00 s: 0. 0060 TcReach - Shallow L: 80. 00 ks: 5. 00 s: 0. 0060 PEAK RATE: 0.76 cfs VOL: 0. 40 Ac-ft TIME: 480 min 5/5/98 10: 51: 31 am Barghausen Engineers page 4 QFC\WALGREENS - RENTON, WA WORKS4 FILE NO. 6116DET.BSN BCE # 6116 BASIN SUMMARY BASIN ID: wet02 NAME: 1/3 2YR/24HR POSTDEV-wetpond SBUH METHODOLOGY TOTAL AREA. . . . . . . : 7.42 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 0. 67 inches AREA. . : 1. 32 Acres 6. 10 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . . 23 .82 min 8.96 min ABSTRACTION COEFF: 0.20 TcReach - Sheet L: 100. 00 ns: 0. 2400 p2yr: 2 . 00 s: 0. 0100 impTcReach - Sheet L: 100. 00 ns: 0. 0110 p2yr: 2 . 00 s: 0. 0150 impTcReach - Channel L: 856. 00 kc:42 .00 s: 0. 0022 PEAK RATE: 0. 65 cfs VOL: 0.24 Ac-ft TIME: 480 min 5/5/98 10: 51: 31 am Barghausen Engineers page 5 QFC\WALGREENS - RENTON, WA WORKS4 FILE NO. 6116DET.BSN BCE # 6116 HYDROGRAPH SUMMARY PEAK TIME VOLUME HYD RUNOFF OF OF Contrib NUM RATE PEAK HYDRO Area cfs min. cf\AcFt Acres 1 0. 090 960 5469 cf 7.42 2 0. 090 1470 13244 cf 7. 42 3 0.283 1450 20100 cf 7.42 4 0.429 1360 31759 cf 7 .42 5 0.895 980 57097 cf 7. 42 6 0.080 1470 11909 cf 7 .42 7 0. 090 1470 13245 cf 7 .42 8 0. 290 1460 20794 cf 7 .42 9 0. 657 1340 44693 cf 7.42 5/5/98 10: 51: 35 am Barghausen Engineers page 6 QFC\WALGREENS - RENTON, WA WORKS4 FILE NO. 6116DET.BSN BCE # 6116 STORAGE STRUCTURE LIST STORAGE LIST ID No. DESIGN Description: DESIGN DETENTION POND STORAGE LIST ID No. FINAL Description: DESIGN DETENTION POND 5/5/98 10 : 51 : 35 am Barghausen Engineers page 7 QFC\WALGREENS - RENTON, WA WORKS4 FILE NO. 6116DET.BSN BCE # 6116 STAGE STORAGE TABLE CUSTOM STORAGE ID No. DESIGN Description: DESIGN DETENTION POND STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- 395.00 0.0000 0.0000 396.30 18143 0.4165 397.60 38448 0.8826 398.90 58753 1.3488 395.10 1346 0.0309 396.40 19705 0.4524 397.70 40010 0.9185 399.00 60315 1.3846 395.20 2691 0.0618 396.50 21267 0.4882 397.80 41572 0.9544 399.10 61960 1.4224 395.30 4037 0.0927 396.60 22829 0.5241 397.90 43134 0.9902 399.20 63605 1.4602 395.40 5383 0.1236 396.70 24391 0.5599 398.00 44696 1.0261 399.30 65249 1.4979 395.50 6729 0.1545 396.80 25952 0.5958 398.10 46258 1.0619 399.40 66894 1.5357 395.60 8074 0.1854 396.90 27514 0.6316 398.20 47820 1.0978 399.50 68539 1.5734 395.70 9420 0.2163 397.00 29076 0.6675 398.30 49381 1.1336 399.60 70184 1.6112 395.80 10766 0.2471 397.10 30638 0.7034 398.40 50943 1.1695 399.70 71829 1.6490 395.90 12111 0.2780 397.20 32200 0.7392 398.50 52505 1.2054 399.80 73473 1.6867 396.00 13457 0.3089 397.30 33762 0.7751 398.60 54067 1.2412 399.90 75118 1.7245 396.10 15019 0.3448 397.40 35324 0.8109 398.70 55629 1.2771 400.00 76763 1.7622 396.20 16581 0.3806 397.50 36886 0.8468 398.80 57191 1.3129 5/5/98 10 : 51: 35 am Barghausen Engineers page 8 QFC\WALGREENS - RENTON, WA WORKS4 FILE NO. 6116DET.BSN BCE # 6116 STAGE STORAGE TABLE CUSTOM STORAGE ID No. FINAL Description: DESIGN DETENTION POND STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- -------------------------------------------------------------------------------------------------------- 395.00 0.0000 0.0000 396.30 23587 0.5415 397.60 49983 1.1475 398.90 76380 1.7534 395.10 1750 0.0402 396.40 25617 0.5881 397.70 52014 1.1941 399.00 78410 1.8000 395.20 3499 0.0803 396.50 27648 0.6347 397.80 54044 1.2407 399.10 80548 1.8491 395.30 5249 0.1205 396.60 29678 0.6813 397.90 56075 1.2873 399.20 82687 1.8982 395.40 6998 0.1607 396.70 31709 0.7279 398.00 58105 1.3339 399.30 84825 1.9473 395.50 8748 0.2008 396.80 33739 0.7745 398.10 60136 1.3805 399.40 86963 1.9964 395.60 10497 0.2410 396.90 35770 0.8212 398.20 62166 1.4271 399.50 89102 2.0455 395.70 12247 0.2811 397.00 37800 0.8678 398.30 64197 1.4737 399.60 91240 2.0946 395.80 13996 0.3213 397.10 39831 0.9144 398.40 66227 1.5204 399.70 93378 2.1437 395.90 15746 0.3615 397.20 41861 0.9610 398.50 68258 1.5670 399.80 95516 2.1928 396.00 17495 0.4016 397.30 43892 1.0076 398.60 70288 1.6136 399.90 97655 2.2418 396.10 19526 0.4482 397.40 45922 1.0542 398.70 72319 1.6602 400.00 99793 2.2909 396.20 21556 0.4949 397.50 47953 1.1008 398.80 74349 1.7068 5/5/98 10: 51: 36 am Barghausen Engineers page 9 QFC\WALGREENS - RENTON, WA WORKS4 FILE NO. 6116DET.BSN BCE # 6116 DISCHARGE STRUCTURE LIST NOTCH WEIR ID No. 100YR Description: NOTCH WEIR OUTFLOW Weir Length: 0.6900 ft. Weir height (p) : 3 .2300 ft. Elevation : 398 . 16 ft. Weir Increm: 0. 10 COMBINATION DISCHARGE ID No. 2/5 Description: ORIFICE/WEIR COMBO Structure: 2YR Structure: Structure: 5YR Structure: Structure: MULTIPLE ORIFICE ID No. 2YR Description: RELEASE 1/2 2YR/24HR EX FLOW Outlet Elev: 394.93 Elev: 392.93 ft Orifice Diameter: 1.4399 in. NOTCH WEIR ID No. 5YR Description: NOTCH WEIR OUTFLOW Weir Length: 0. 3100 ft. Weir height (p) : 2 . 5500 ft. Elevation : 397. 48 ft. Weir Increm: 0. 10 COMBINATION DISCHARGE ID No. COMBINE Description: ORIFICE/WEIR/WEIR COMBO Structure: 2YR Structure: Structure: 5YR Structure: Structure: 100YR 5/5/98 10: 51: 36 am Barghausen Engineers page 10 QFC\WALGREENS - RENTON, WA WORKS4 FILE NO. 6116DET.BSN BCE # 6116 STAGE DISCHARGE TABLE NOTCH WEIR ID No. 100YR Description: NOTCH WEIR OUTFLOW Weir Length: 0.6900 ft. Weir height (p) : 3 .2300 ft. Elevation : 398 . 16 ft. Weir Increm: 0. 10 STAGE <--DISCHARGE---> STAGE -DISCHARGE---> STAGE -DISCHARGE---> STAGE -DISCHARGE---> (ft) ---CfS-- ------- (ft) ---CfS-- ------- (ft) ---CfS-- ------- (ft) ---CfS-- ------- 398.16 0.0000 398.60 0.5841 399.10 1.5493 399.60 2.3954 398.20 0.0179 398.70 0.7706 399.20 1.7375 399.70 2.5264 398.30 0.1140 398.80 0.9637 399.30 1.9182 399.80 2.6405 398.40 0.2491 398.90 1.1598 399.40 2.0895 399.90 2.7360 398.50 0.4084 399.00 1.3559 399.50 2.2491 400.00 2.8112 5/5/98 10: 51: 36 am Barghausen Engineers page 11 QFC\WALGREENS - RENTON, WA WORKS4 FILE NO. 6116DET.BSN BCE # 6116 STAGE DISCHARGE TABLE COMBINATION DISCHARGE ID No. 2/5 Description: ORIFICE/WEIR COMBO Structure: 2YR Structure: Structure: 5YR Structure: Structure: STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> (ft) ---CfS-- ------- (ft) ---CfS-- ------- (ft) ---CfS-- ------- (ft) ---CfS-- ------- 394.93 0.0000 396.20 0.0634 397.50 0.0930 398.80 0.3533 395.00 0.0149 396.30 0.0659 397.60 0.1310 398.90 0.2658 395.10 0.0232 396.40 0.0682 397.70 0.1843 399.00 0.1530 395.20 0.0292 396.50 0.0705 397.80 0.2432 399.10 0.1149 395.30 0.0342 396.60 0.0727 397.90 0.3022 399.20 0.1163 395.40 0.0386 396.70 0.0749 398.00 0.3575 399.30 0.1176 395.50 0.0425 396.80 0.0769 398.10 0.4059 399.40 0.1190 395.60 0.0461 396.90 0.0790 398.20 0.4448 399.50 0.1203 395.70 0.0494 397.00 0.0810 398.30 0.4717 399.60 0.1216 395.80 0.0525 397.10 0.0829 398.40 0.4844 399.70 0.1229 395.90 0.0554 397.20 0.0848 398.50 0.4809 399.80 0.1242 396.00 0.0582 397.30 0.0866 398.60 0.4590 399.90 0.1254 396.10 0.0609 397.40 0.0884 398.70 0.4171 400.00 0.1267 5/5/98 10: 51: 37 am Barghausen Engineers page 12 QFC\WALGREENS - RENTON, WA WORKS4 FILE NO. 6116DET.BSN BCE # 6116 STAGE DISCHARGE TABLE MULTIPLE ORIFICE ID No. 2YR Description: RELEASE 1/2 2YR/24HR EX FLOW Outlet Elev: 394 . 93 Elev: 392 . 93 ft Orifice Diameter: 1. 4399 in. STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE -DISCHARGE---> STAGE -DISCHARGE---> (ft) ---CfS-- ------- (ft) ---CfS-- ------- (ft) ---CfS-- ------- (ft) ---CfS-- ------- 394.93 0.0000 396.20 0.0634 397.50 0.0902 398.80 0.1107 395.00 0.0149 396.30 0.0659 397.60 0.0919 398.90 0.1121 395.10 0.0232 396.40 0.0682 397.70 0.0936 399.00 0.1135 395.20 0.0292 396.50 0.0705 397.80 0.0953 399.10 0.1149 395.30 0.0342 396.60 0.0727 397.90 0.0970 399.20 0.1163 395.40 0.0386 396.70 0.0749 398.00 0.0986 399.30 0.1176 395.50 0.0425 396.80 0.0769 398.10 0.1002 399.40 0.1190 395.60 0.0461 396.90 0.0790 398.20 0.1017 399.50 0.1203 395.70 0.0494 397.00 0.0810 398.30 0.1033 399.60 0.1216 395.80 0.0525 397.10 0.0829 398.40 0.1048 399.70 0.1229 395.90 0.0554 397.20 0.0848 398.50 0.1063 399.80 0.1242 396.00 0.0582 397.30 0.0866 398.60 0.1078 399.90 0.1254 396.10 0.0609 397.40 0.0884 398.70 0.1093 400.00 0.1267 5/5/98 10: 51: 37 am Barghausen Engineers page 13 QFC\WALGREENS - RENTON, WA WORKS4 FILE NO. 6116DET.BSN BCE # 6116 STAGE DISCHARGE TABLE NOTCH WEIR ID No. 5YR Description: NOTCH WEIR OUTFLOW Weir Length: 0.3100 ft. Weir height (p) : 2 .5500 ft. Elevation : 397 .48 ft. Weir Increm: 0. 10 STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> (ft) ---CfS-- ------- (ft) ---CfS-- ------- (ft) ---CfS-- ------- (ft) ---CfS-- ------- 397.48 0.0000 397.90 0.2052 398.40 0.3796 398.90 0.1537 397.50 0.0028 398.00 0.2589 398.50 0.3745 399.00 0.0394 397.60 0.0391 398.10 0.3058 398.60 0.3512 399.10 0.0000 397.70 0.0907 398.20 0.3431 398.70 0.3078 397.80 0.1479 398.30 0.3684 398.80 0.2426 5/5/98 10: 51: 38 am Barghausen Engineers page 14 QFC\WALGREENS - RENTON, WA WORKS4 FILE NO. 6116DET.BSN BCE # 6116 STAGE DISCHARGE TABLE COMBINATION DISCHARGE ID No. COMBINE Description: ORIFICE/WEIR/WEIR COMBO Structure: 2YR Structure: Structure: 5YR Structure: Structure: 100YR STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> (ft) ---CfS-- ------- (ft) ---Cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfS-- ------- 394.93 0.0000 396.20 0.0634 397.50 0.0930 398.80 1.3170 395.00 0.0149 396.30 0.0659 397.60 0.1310 398.90 1.4256 395.10 0.0232 396.40 0.0682 397.70 0.1843 399.00 1.5089 395.20 0.0292 396.50 0.0705 397.80 0.2432 399.10 1.6642 395.30 0.0342 396.60 0.0727 397.90 0.3022 399.20 1.8538 395.40 0.0386 396.70 0.0749 398.00 0.3575 399.30 2.0359 395.50 0.0425 396.80 0.0769 398.10 0.4059 399.40 2.2084 395.60 0.0461 396.90 0.0790 398.20 0.4627 399.50 2.3694 395.70 0.0494 397.00 0.0810 398.30 0.5857 399.60 2.5170 395.80 0.0525 397.10 0.0829 398.40 0.7335 399.70 2.6493 395.90 0.0554 397.20 0.0848 398.50 0.8893 399.80 2.7647 396.00 0.0582 397.30 0.0866 398.60 1.0431 399.90 2.8614 396.10 0.0609 397.40 0.0884 398.70 1.1877 400.00 2.9379 5/5/98 10: 51:42 am Barghausen Engineers page 15 QFC\WALGREENS - RENTON, WA WORKS4 FILE NO. 6116DET.BSN BCE # 6116 LEVEL POOL TABLE SUMMARY MATCH INFLOW -STO- -DIS- <-PEAK-> STORAGE <--------DESCRIPTION---------> (cfs) (cfs) --id- --id- <-STAGE> id VOL (cf) 1/2 2YR/24HR DESIGN .......... 0.09 2.48 DESIGN 2YR 397.48 2 36538.08 cf 5 YR/24 HR DESIGN ............ 0.28 3.06 DESIGN 2/5 397.87 3 42628.56 cf 10 YR/24 HR DESIGN ........... 0.44 3.79 DESIGN 2/5 398.16 4 47187.29 cf 100 YR/24 HR DESIGN .......... 0.89 5.27 DESIGN COMBINE 398.50 5 52562.78 cf 2 YR/24 HR FINAL ............. 0.00 2.48 FINAL COMBINE 396.97 6 37093.74 cf 5 YR/24 HR FINAL ............. 0.00 3.06 FINAL COMBINE 397.43 7 46579.96 cf 10 YR/24 HR FINAL ............ 0.00 3.79 FINAL COMBINE 397.88 8 55655.57 cf 100 YR/24 HR FINAL ........... 0.00 5.27 FINAL COMBINE 398.35 9 65176.97 cf WETLAND RECHARGE CALCULATIONS �ET(�iy© (L-�C��4��� G�4[..G✓lam%iocJS __ i L X(5 i;',uG i4tZ%.9 'b wrrLAA)D u s Z s o �2G E� o!L 2c wo�I 7a sr�1Sr cc ps cs Ue n,-R p05 i 61. 5—1 ok 14 { I i Q 200f�24(N�46� �jr�M Sa¢OPS �4 A �v/Lnitilr _ n,�,a�-G{� VoL v t E —� USA �a 4 D��, o(L.cFcG� CSo'2s �L,;owt.v G Cr4LG s� I I 1 � i I I i I i i � �Lo�-J Sz'�Zdc•-u1z�. Y 9 D FL. 39e► .� i J 0 3g S-o I D 1 Q,Z Ta 4- GM4-0 = U,O / GFs is lar Z 6.lOZ/4 Z(3Z.2) rl �1 = O. bow P14/4eT&PZ 62(FtG6'- /N 2I34'2 —0 e✓ i sue//) I 5/6/98 11:24 : 3 am Barghausen Engineers page 1 QFC\WALGREENS WETLAND RECHARGE CALCULATIONS BCE # 6116 BASIN SUMMARY BASIN ID: A4 NAME: 2YR/24HR POSTDEV TO WETLAND SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 09 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : KC24HR PERV IMP PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0. 00 Acres 0. 09 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 0. 00 98. 00 TC. . . . . 0. 00 min 6. 30 min ABSTRACTION COEFF: 0. 20 TcReach - Sheet L: 260. 00 ns: 0.4000 p2yr: 2 . 00 s: 0. 0115 PEAK RATE: 0. 04 cfs VOL: 0. 01 Ac-ft TIME: 470 min V. CONVEYANCE SYSTEM DESIGN AND ANALYSIS CATCH BASIN SCFEDULE I, f=IJ GRADING AND STORM DRAINAGE PLAN CB, 1,TYPE t CB, 11,TYPE , CHI,21.TYPE 1 U) RN=399.2q RM=399.0Q RIM=398.0p Frisr- SAMv E=396.97(87 IE-3962.22( 3 127 IE=395.12(127 ^ j m- I. Xf=JYJ49(-V�Y TYPE 1 m= T/f=J9J 59(le NJ) RIM_ 2Q - i E=395. CBD 2,TYPE 1 TYPE 2 18 IF 394.29 I r-ao� � z�8, �' 7(12 15 ,8 z r. / ± ; _.. --------------------- --- ---------- ----- --'-------- 0 zo ,O 00 TYPE 1 %7TYPE I (12� RIM h-• Q XE.=J9J.95(J6lA'E i ------------ ---------------- co__ - - ____.-______ 17 ICONTROL STRUCTURE - i __________________________________._______ PER DETAIL __________ CORNER _ __.__,__a ____________ /F=J9J 9J(J6XE �' �0423.00 _____________________________._ ___ 8+46. -_____..________ sn.e 1 E 394.93 .I ,WIRE FENCE CDR. _ _ __ 1.56 W.t. I - 6� E 3957 12 15 ,pROR \ �!.TYPE f'E/ 1�4&TYPE 1 . � _________ ___ RIM 399.05 ('� ___________ RM=399.1 _ Y z- G9•T 130 12•SD 399.60 _______________ _____________ - E-396.61?12•t 67 IE=396.12�8 r 18-50 022>< 390g'so _ -T---- - -, v W = I .I. -(.'� -- I _ _ ZT 1- \ / CBD 5.TYPE 1 CBD 15,TYPE 1 CBD 24.TYPE 2-48• I I r\141TT1"ie -0�4 - - _ 0p 1J KT'I CB 7. 1l6 1 -._ I I -\\I I(I 1 I // / \ / 396 b9(8� PoY395 IEM394 59(18•) W j I! N4L(. ) / II I R00-2_4 '! IG CB/ 5.TYPE 1 RM=398.7 -k -) CBJ 25,TYPE 2-48• ALL I 6 IE=397s6 7RIM 98S2 W O. sM wAmr C MFENCE zQ jAc.�p*G� 0. Z 5954IPUMP SYSTEM 7AININC WALL C8J 7.TYPE t CBS 1 .TYPE 2-48• RIM=399.t 1 RM-398.70 IF-395.40(157 CB/26,TYPE 2-48• O J W I , I I / \ / E-396.44(87ir I I I Pc .... II I I• -/� i i / I i / \ / CfW81AD=399. . R= 9tM=3.3 Q RIM 3698.6 0 SO E-39 .,,, J O 1 I I ' i (/ ( I I I C 27•TYPE 1 W i I I I .90 E=396.29(8•d 12-)i �' II - - -- d M_C H R ■IG ,I/, i/�� \\\ /// PoII= R Q Z RN 19. 1 M M2�MPC8/ 1 RN-39830 WSU E-396.07(8•t 12-)MENL1p 8E=396.1412') 0 � 10.TYPE t �20,TYPE 1 J Q t \ - / RM-399.00 15, I I I `� N �,� / \ E=396.54(8' ImEM395.8(12' 1 .',-__ ___ _II NrAvn I II- -^--♦�� .0 m � I Oe 3/QG f �I I BOTTOM -POND-jL=391.0 OM EL-395.0 j EL-398 M R TOP POND=399.0 / \ SEE DEFI�ON SHEET 4 m I1 of 7S I \ 32 LF IIr l i \ I In I 77« \I✓l CPEP O 0.47% `1��---- -_- I i I ii■ I f 0r42a a \ --- --I ;\I I I 9 I 40 O•6,4-QG• I I I I 5 I Il .__e •w I ._. ._ _._er I. o •X: 41 \ fi 1 LEGEND 1 I 8 I I I I I I __ �__ _____ _ _ __Z•N-.r •• I I \ 1 I \ O I I l I I ) - µ 01 3 I I ;I\ ;; -- PROPOSED TYPE I CATCH BASH • y 128 IF 8-d 024X `^•'�n I �I .�2;, - ------------- 'i v 17 CM YL 1. • I , 1 , PROPOSED TYPE I CATCH BASIN ■ W m I .'� C� 1�2sa= ]IW.eD t.Yss 3W79 1 O 024 1 4% 1' 09 LF iS• `r' p RETAI�WAIL 1 I ' �I \WEIGHY VARIES) EXISTING TYPE R CATCH 81SM ® cc � � I 70 , »I. W � 11 o _ T� O d22X~ I I EXISTING TYPE I CATCH BASIN ❑ I W I / ♦ PROPOSED STORM DRAINAGE NNE . I9 8HOP5 Ad I � I ♦ / � ----------------- EXISTING S10R11 DRAINAGE LINE PROPOSED SANITARY SEWER MANHOLE WET LAND BUFFER 1 1 1 QJ L r H I 1 EXISTING SANITARY SEWER MANHOLE O NNK I O W PROPOSED SANITARY SEWER LINE 25 IF FLOW DISPERSAL TRENCH EXISTING SANITARY SEWER LINE O 1.0% SEE DETAIL SHEET 9 I EEL 1 i 1 / .>b •� Allll SEE NOTE EXISTING WATERIMN OW ..1 ------------- ----'------------------ 1 _ y PROPOSED WATERMMI Lo O 24% -024L- �S{l \ L L Y y EXISTING TWIFTC SIONAI BOX EXISTOW WERA►OI I I 1 EDGE OF RELOCATED WETLMOS S .......... DRS i I JIA10 9__. __ •b o \ _ o J19.J0 ' y ` EDGE OF EXISTING WETLANDS y J V) X Ed 4 ( }� ,• •'• ••��• EXISTING DITCH �- j N z y YC0 I�f 24X- 7 _ --------- ------- E70STNG CONTOURS - - & ----- --- L�R� I • . I4 .•W y W �� 396 Zno an10 0 M. 1 11 RELOCATED WETLAND I N f n4 r- ----- PROPOSED SPOT ELEVATION 7 E LINE ............................. ^� QQ8 In rsr Q/ - Ii 41 W W O O ,�_ ______ _____ r I {� • o TO . • �•• W �v AT IXIS G 1CN BIISIN TO BEt11NNO NCF0W16 A1SRpI1fCQTIOi N �m RELOCATED NOTED nE ANDS\" OR SHALL FIELD EVRT 0_\%TN CONTRA O�b�i WAS 'MF BUFFER WETLAND 'A'� (12,•821 SFr.) CONT ENGINEER AWDIATEL F THE NN.Rt ELEVATION •- I I OS•40 .,' _ I I .J VARIES E ON F ANSi O I R 35.00• \� ��- i' I \�•/ ; o *••' W W w L OROSM. TO DISPERSAL J I t I - I 011 `t, WET REC ___________�_TJ,,4_ - WATER a"C.I. - .._ ♦• •♦•♦ -`' 0/RE FOR SYSTEM ROUTED 9 `5672 Q /.E=393 69 -__-_ -- ... Af.-J9e � 0 9f �� V. fJs/DNA L7 L �� � aJv 95 SIGNAL .F.=J9J. fi _e Ex W .. Ih ___ AE.-AStF< EXPIRES (40 s eero' A' = IX n� _ -------------0 014% EX Go 1 E>IEPARTME OF RENTON SKAML \ 170 LF IIr aEv COnNECT To '- • Fdtfhq r=ia W ' .x:u..r NE 4th 8T - (SE 1 f""--------- ---- -- �2 ST� T--- E=J93.09 ,/ 37(re TA IY.F --------- ---__-I-y._• � Axorm A4.'o A+Nrf. �FOTE t �FIIO sE(/e^Sl - - /E.-J9J /F=J9J ---- DRAINAGE AREA MAP 9 -------- - 8F�T8 4 ADD 5 FOR iiDADMUYlYPBQyB11�IJ __------•_1 L 1 ALaio DE<il I Sff)EEf ND SURFACE MONVMENT�� .(i�QR CT. 10 05 __ TT OV 70 o f95 J O -- '---------------------------- --------o121aXzo1F:'= �pe's) GATT: 1-16-98 H10. 7 -- DAWN N CHECK DKO WC TTt 1-=40• 900K PACE W 1 Hn w*W� 2 CF i Ric �k. P.\SDSXPLbJ\6116\ENGINEERING\6115-GM I.CYWC Ni-/T„ne: 01/15/I9GR 16:25 S-fe. 1=40 Allen X,els. 7FI16-A,7F116-S;7Fll6-T,761IF-Ft. m 1/15/98 3 : 11: 30 pm Barghausen Engineers page 1 QFC\WALGREENS - RENTON, WA STORM DRAINAGE CONVEYANCE CALCULATIONS BCE # 6116 BASIN SUMMARY BASIN ID: cb01 NAME: Catch basin #1 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 19 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 . 40 inches AREA. . : 0. 01 Acres 0. 18 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . : 10. 00 min 10. 00 min ABSTRACTION COEFF: 0. 20 PEAK RATE: 0. 13 cfs VOL: 0. 05 Ac-ft TIME: 480 min BASIN ID: cb02 NAME: Catch basin #2 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 24 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 .40 inches AREA. . : 0. 01 Acres 0. 23 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . : 10. 00 min 10. 00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0. 16 cfs VOL: 0. 06 Ac-ft TIME: 480 min BASIN ID: cb03 NAME: Catch basin #3 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.22 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 .40 inches AREA. . : 0. 01 Acres 0. 21 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . . 110. 00 min 10. 00 min ABSTRACTION COEFF: 0. 20 PEAK RATE: 0. 15 cfs VOL: 0.06 Ac-ft TIME: 480 min BASIN ID: cb04 NAME: Catch basin #4 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 43 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 .40 inches AREA. . : 0. 03 Acres 0.40 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . : 10. 00 min 10. 00 min ABSTRACTION COEFF: 0. 20 PEAK RATE: 0.28 cfs VOL: 0. 11 Ac-ft TIME: 480 min 1/15/98 3 : 11: 30 pm Barghausen Engineers page 2 QFC\WALGREENS - RENTON, WA STORM DRAINAGE CONVEYANCE CALCULATIONS BCE # 6116 BASIN SUMMARY BASIN ID: cb05 NAME: Catch basin #5 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 10 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 . 40 inches AREA. . : 0. 02 Acres 0. 08 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . : 10. 00 min 10. 00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0. 06 cfs VOL: 0. 02 Ac-ft TIME: 480 min BASIN ID: cb06 NAME: Catch basin #6 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 28 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 .40 inches AREA. . : 0. 02 Acres 0.26 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . : 10. 00 min 10. 00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0. 18 cfs VOL: 0. 07 Ac-ft TIME: 480 min BASIN ID: cb07 NAME: Catch basin #7 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 19 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 .40 inches AREA. . : 0. 02 Acres 0. 17 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98.00 TC. . . . . '10. 00 min 10. 00 min ABSTRACTION COEFF: 0. 20 PEAK RATE: 0. 12 cfs VOL: 0. 05 Ac-ft TIME: 480 min BASIN ID: cb08 NAME: Catch basin #8 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 16 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 .40 inches AREA. . : 0. 02 Acres 0. 14 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . : 10. 00 min 10. 00 min ABSTRACTION COEFF: 0. 20 PEAK RATE: 0. 10 cfs VOL: 0. 04 Ac-ft TIME: 480 min 1/15/98 3 : 11: 30 pm Barghausen Engineers page 3 QFC\WALGREENS - RENTON, WA STORM DRAINAGE CONVEYANCE CALCULATIONS BCE # 6116 BASIN SUMMARY BASIN ID: cb09 NAME: Catch basin #9 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.25 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 . 40 inches AREA. . : 0. 02 Acres 0.23 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . : 10. 00 min 10.00 min ABSTRACTION COEFF: 0. 20 PEAK RATE: 0. 16 cfs VOL: 0. 06 Ac-ft TIME: 480 min BASIN ID: cb10 NAME: Catch basin #10 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.25 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 .40 inches AREA. . : 0. 02 Acres 0. 23 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98 . 00 TC. . . . : 10. 00 min 10.00 min ABSTRACTION COEFF: 0. 20 PEAK RATE: 0. 16 cfs VOL: 0. 06 Ac-ft TIME: 480 min BASIN ID: cbll NAME: Catch basin #11 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 42 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 .40 inches AREA. . : 0. 03 Acres 0. 39 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . : '10. 00 min 10. 00 min ABSTRACTION COEFF: 0. 20 PEAK RATE: 0.28 cfs VOL: 0. 11 Ac-ft TIME: 480 min BASIN ID: cb12 NAME: Catch basin #12 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 19 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 3 .40 inches AREA. . : 0. 02 Acres 0. 17 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . : 10. 00 min 10. 00 min ABSTRACTION COEFF: 0. 20 PEAK RATE: 0. 12 cfs VOL: 0. 05 Ac-ft TIME: 480 min 1/15/98 3 : 11: 30 pm Barghausen Engineers page 4 QFC\WALGREENS - RENTON, WA STORM DRAINAGE CONVEYANCE CALCULATIONS BCE # 6116 --------------------------------------------------------------------- BASIN SUMMARY BASIN ID: cb13 NAME: Catch basin #13 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 64 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 . 40 inches AREA. . : 0. 04 Acres 0. 60 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . : 10. 00 min 10. 00 min ABSTRACTION COEFF: 0. 20 PEAK RATE: 0. 42 cfs VOL: 0. 16 Ac-ft TIME: 480 min BASIN ID: cb14 NAME: Catch basin #14 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 09 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 . 40 inches AREA. . : 0. 03 Acres 0. 06 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98 . 00 TC. . . . : 10. 00 min 10. 00 min ABSTRACTION COEFF: 0. 20 PEAK RATE: 0. 05 cfs VOL: 0. 02 Ac-ft TIME: 480 min BASIN ID: cb15 NAME: Catch basin #15 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 17 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 . 40 inches AREA. . : 0. 01 Acres 0. 16 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . : '10. 00 min 10. 00 min ABSTRACTION COEFF: 0. 20 PEAK RATE: 0. 11 cfs VOL: 0. 04 Ac-ft TIME: 480 min BASIN ID: cb16 NAME: Catch basin #16 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 23 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 . 40 inches AREA. . : 0. 02 Acres 0. 21 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . : 10. 00 min 10. 00 min ABSTRACTION COEFF: 0. 20 PEAK RATE: 0. 15 cfs VOL: 0. 06 Ac-ft TIME: 480 min 1/15/98 3 : 11: 30 pm Barghausen Engineers page 5 QFC\WALGREENS - RENTON, WA STORM DRAINAGE CONVEYANCE CALCULATIONS BCE # 6116 BASIN SUMMARY BASIN ID: cb17 NAME: Catch basin #17 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 37 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 . 40 inches AREA. . : 0. 04 Acres 0. 33 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . : 10. 00 min 10. 00 min ABSTRACTION COEFF: 0. 20 PEAK RATE: 0. 24 cfs VOL: 0. 09 Ac-ft TIME: 480 min BASIN ID: cb18 NAME: Catch basin #18 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 27 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 3 . 40 inches AREA. . : 0. 01 Acres 0.26 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . : 10. 00 min 10.00 min ABSTRACTION COEFF: 0. 20 PEAK RATE: 0. 18 cfs VOL: 0. 07 Ac-ft TIME: 480 min BASIN ID: cb19 NAME: Catch basin #19 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 21 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 .40 inches AREA. . : 0. 02 Acres 0. 19 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . . '10. 00 min 10. 00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0. 14 cfs VOL: 0.05 Ac-ft TIME: 480 min BASIN ID: cb20 NAME: Catch basin #20 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.71 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 .40 inches AREA. . : 0. 00 Acres 0.71 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . : 10. 00 min 10. 00 min ABSTRACTION COEFF: 0. 20 PEAK RATE: 0. 49 cfs VOL: 0. 19 Ac-ft TIME: 480 min 1/15/98 3 : 11: 31 pm Barghausen Engineers page 6 QFC\WALGREENS - RENTON, WA STORM DRAINAGE CONVEYANCE CALCULATIONS BCE # 6116 BASIN SUMMARY BASIN ID: cb21 NAME: Catch basin #21 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.40 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 .40 inches AREA. . : 0. 00 Acres 0. 40 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . : 10. 00 min 10. 00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0. 27 cfs VOL: 0. 11 Ac-ft TIME: 480 min BASIN ID: cb22 NAME: Catch basin #22 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 19 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 3 . 40 inches AREA. . : 0. 02 Acres 0. 17 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 80. 00 98. 00 TC. . . . : 10. 00 min 10.00 min ABSTRACTION COEFF: 0. 20 PEAK RATE: 0. 12 cfs VOL: 0. 05 Ac-ft TIME: 480 min 1/15/98 3 : 11: 31 pm Barghausen Engineers page 7 QFC\WALGREENS - RENTON, WA STORM DRAINAGE CONVEYANCE CALCULATIONS BCE # 6116 HYDROGRAPH SUMMARY PEAK TIME VOLUME HYD RUNOFF OF OF Contrib NUM RATE PEAK HYDRO Area cfs min. cf\AcFt Acres 1 4 . 076 480 68818 cf 6.20 1/15/98 3 : 11: 38 pm Barghausen Engineers page 8 QFC\WALGREENS - RENTON, WA STORM DRAINAGE CONVEYANCE CALCULATIONS BCE # 6116 REACH SUMMARY Network Reach N01 REACH <-AREA> <-DIA> LENGTH SLOPE < n > DSGN Q % PIPE Ndepth %Depth Vact Vfull C_Area ID (Ac) (ft) (ft) ft/ft ------ (cfs) ------ (ft) ------ (fps) (fps) P01 0.19 0.67 64.00 0.0023 0.0120 0.13 18.43 0.20 30.19 1.42 2.01 cb01 P02 0.43 0.67 90.00 0.0024 0.0120 0.29 41.00 0.31 46.49 1.80 2.05 cb02 Network Reach NO3 REACH <-AREA> <-DIA> LENGTH SLOPE < n > DSGN Q % PIPE Ndepth %Depth Vact Vfull C_Area ID (Ac) (ft) (ft) ft/ft ------ (cfs) ------ (ft) ------ (fps) (fps) P03 0.22 0.67 128.00 0.0020 0.0120 0.15 23.02 0.23 33.90 1.41 1.87 cb03 Network Reach N04 REACH <-AREA> <-DIA> LENGTH SLOPE < n > DSGN Q % PIPE Ndepth %Depth Vact Vfull C_Area ID (Ac) (ft) (ft) ft/ft ------ (cfs) ------ (ft) ------ (fps) (fps) Confluence with Network N01 Confluence with Network NO3 PO4 1.08 1.00 131.00 0.0024 0.0120 0.72 35.31 0.43 42.73 2.23 2.65 cb04 Network Reach N05 REACH <-AREA> <-DIA> LENGTH SLOPE < n > DSGN Q % PIPE Ndepth %Depth ' Vact Vfull C_Area ID (Ac) (ft) (ft) ft/ft ------ (cfs) ------ (ft) ------ (fps) (fps) P05 0.10 0.67 64.00 0.0020 0.0120 0.06 9.54 0.14 21.63 1.09 1.87 cb05 Network Reach NO6 REACH <-AREA> <-DIA> LENGTH SLOPE < n > DSGN Q % PIPE Ndepth %Depth Vact Vfull C_Area ID (Ac) (ft) (ft) ft/ft ------ (cfs) ------ (ft) ------ (fps) (fps) P06 0.28 0.67 68.00 0.0021 0.0120 0.18 28.67 0.25 38.12 1.50 1.88 cb06 Network Reach N07 REACH <-AREA> <-DIA> LENGTH SLOPE < n > DSGN Q % PIPE Ndepth %Depth Vact VfuLL C_Area ID (Ac) (ft) (ft) ft/ft ------ (cfs) ------ (ft) ------ (fps) (fps) Confluence with Network N05 Confluence with Network N06 P07 0.57 0.67 67.00 0.0019 0.0120 0.37 58.95 0.39 57.81 1.75 1.83 cb07 1/15/98 3 : 11: 39 pm Barghausen Engineers page 9 QFC\WALGREENS - RENTON, WA STORM DRAINAGE CONVEYANCE CALCULATIONS BCE # 6116 REACH SUMMARY Network Reach N08 REACH <-AREA> <-DIA> LENGTH SLOPE < n > DSGN Q % PIPE Ndepth %Depth Vact VfuLL C_Area ID (Ac) (ft) (ft) ft/ft ------ (cfs) ------ (ft) ------ (fps) (fps) Confluence with Network N04 Confluence with Network N07 P08 1.81 1.00 65.00 0.0025 0.0120 1.18 57.30 0.57 56.77 2.57 2.70 cb08 P09 2.06 1.00 173.00 0.0024 0.0120 1.35 65.65 0.62 62.01 2.63 2.68 cb09 Network Reach N10 REACH <-AREA> <-DIA> LENGTH SLOPE < n > DSGN Q % PIPE Ndepth %Depth Vact VfuLL C_Area ID (Ac) (ft) (ft) ft/ft ------ (cfs) ------ (ft) ------ (fps) (fps) P10 0.25 0.67 128.00 0.0023 0.0120 0.16 23.91 0.23 34.60 1.52 2.01 cb10 P11 0.67 1.00 65.00 0.0025 0.0120 0.44 21.24 0.33 32.50 1.98 2.70 cbll P12 0.86 1.00 132.00 0.0023 0.0120 0.56 27.81 0.37 37.49 2.09 2.64 cb12 Network Reach N13 REACH <-AREA> <-DIA> LENGTH SLOPE < n > DSGN Q % PIPE Ndepth %Depth Vact VfuLL C_Area ID (Ac) (ft) (ft) ft/ft ------ (cfs) ------ (ft) ------ (fps) (fps) Confluence with Network N08 Confluence with Network N10 P13 3.56 1.25 78.00 0.0026 0.0120 2.33 60.95 0.74 59.06 ' 3.09 3.20 cb13 Network Reach N14 REACH <-AREA> <-DIA> LENGTH SLOPE < n > DSGN Q % PIPE Ndepth %Depth Vact VfuLL C_Area ID (Ac) (ft) (ft) ft/ft ------ (cfs) ------ (ft) ------ (fps) (fps) P14 0.09 0.67 118.00 0.0025 0.0120 0.05 7.03 0.12 18.62 1.12 2.09 cbl4 P15 0.26 0.67 78.00 0.0027 0.0120 0.16 22.17 0.22 33.25 1.60 2.15 cb15 Network Reach N16 REACH <-AREA> <-DIA> LENGTH SLOPE < n > DSGN Q % PIPE Ndepth %Depth Vact Vfull C_Area ID (Ac) (ft) (ft) ft/ft ------ (cfs) ------ (ft) ------ (fps) (fps) Confluence with Network N13 Confluence with Network N14 P16 4.05 1.25 84.00 0.0021 0.0120 2.64 75.60 0.86 68.48 2.95 2.92 cbl6 P17 4.42 1.25 151.00 0.0021 0.0120 2.88 84.19 0.93 74.56 2.93 2.86 cbl7 1/15/98 3 : 11 : 39 pm Barghausen Engineers page 10 QFC\WALGREENS - RENTON, WA STORM DRAINAGE CONVEYANCE CALCULATIONS BCE # 6116 --------------------------------------------------------------------- --------------------------------------------------------------------- REACH SUMMARY Network Reach N18 REACH <-AREA> <-DIA> LENGTH SLOPE < n > DSGN Q % PIPE Ndepth %Depth Vact Vfull C_Area ID (Ac) (ft) (ft) ft/ft ------ (cfs) ------ (ft) ------ (fps) (fps) P18 0.27 0.67 130.00 0.0020 0.0120 0.18 28.61 0.25 38.08 1.48 1.86 cb18 P19 0.48 1.00 140.00 0.0020 0.0120 0.32 17.00 0.29 28.96 1.68 2.43 cb19 P20 1.19 1.00 130.00 0.0020 0.0120 0.80 43.06 0.48 47.82 2.16 2.43 cb20 P21 1.59 1.00 132.00 0.0020 0.0120 1.07 58.18 0.57 57.33 2.31 2.41 cb21 Network Reach N22 REACH <-AREA> <-DIA> LENGTH SLOPE < n > DSGN Q % PIPE Ndepth %Depth Vact Vfull C_Area ID (Ac) (ft) (ft) ft/ft ------ (cfs) ------ (ft) ------ (fps) (fps) ------------------------------------------------------------------------------------------------- ------------------------------------------------------------------------------------------------- Confluence with Network N16 Confluence with Network N18 P22 6.20 1.50 29.00 0.0017 0.0120 4.08 79.98 1.07 71.50 3.02 2.96 cb22 PIPE REACH ID No. P01 From: To: Pipe Diameter: 0. 6667 ft n: 0. 0120 Pipe Length 64 . 0000 ft s: 0. 0023 Up invert : 397 . 5000 ft down invert: 397 . 3500 ft Collection Area: 0. 1900 Ac. Design Flow 0. 1260 cfs Dsgn Depth: 0. 20 ft Pipe Capacity 0. 6836 cfs Design Vel 1. 4183 fps Travel Time: 0. 75 min Pipe Full Vel 2 . 0098 fps PIPE REACH ID No. P02 From: To: Pipe Diameter: 0. 6667 ft n: 0. 0120 Pipe Length 90. 0000 ft s: 0. 0024 Up invert : 397 . 3500 ft down invert: 397 . 1300 ft Collection Area: 0. 4300 Ac. Design Flow 0. 2862 cfs Dsgn Depth: 0. 31 ft Pipe Capacity 0. 6981 cfs Design Vel 1.8006 fps Travel Time: 0. 83 min Pipe Full Vel 2 . 0525 fps 1/15/98 3 : 11: 39 pm Barghausen Engineers page 11 QFC\WALGREENS - RENTON, WA STORM DRAINAGE CONVEYANCE CALCULATIONS BCE # 6116 REACH SUMMARY PIPE REACH ID No. P03 From: To: Pipe Diameter: 0. 6667 ft n: 0. 0120 Pipe Length : 128. 0000 ft s: 0. 0020 Up invert : 397 . 3900 ft down invert: 397 . 1300 ft Collection Area: 0. 2200 Ac. Design Flow 0. 1465 cfs Dsgn Depth: 0. 23 ft Pipe Capacity 0. 6364 cfs Design Vel 1.4055 fps Travel Time: 1. 52 min Pipe Full Vel 1.8710 fps PIPE REACH ID No. PO4 From: To: Pipe Diameter: 1. 0000 ft n: 0. 0120 Pipe Length : 131. 0000 ft s: 0. 0024 Up invert : 397 . 1300 ft down invert: 396.8200 ft Collection Area: 1. 0800 Ac. Design Flow 0.7151 cfs Dsgn Depth: 0. 43 ft Pipe Capacity 2 . 0252 cfs Design Vel 2 . 2328 fps Travel Time: 0.98 min Pipe Full Vel 2 . 6463 fps PIPE REACH ID No. P05 From: To: Pipe Diameter: 0. 6667 ft n: 0.0120 Pipe Length 64 . 0000 ft s: 0. 0020 Up invert : 397. 0800 ft down invert: 396. 9500 ft Collection Area: 0. 1000 Ac. Design Flow 0. 0607 cfs Dsgn Depth: 0. 14 ft Pipe Capacity 0. 6364 cfs Design Vel 1. 0921 fps Travel Time: 0. 98 min Pipe Full Vel 1.8710 fps PIPE REACH ID No. P06 From: To: Pipe Diameter: 0. 6667 ft n: 0.0120 Pipe Length 68 . 0000 ft s: 0. 0021 Up invert : 397 . 0900 ft down invert: 396.9500 ft Collection Area: 0. 2800 Ac. Design Flow 0. 1837 cfs Dsgn Depth: 0. 25 ft Pipe Capacity 0. 6407 cfs Design Vel 1. 5028 fps Travel Time: 0.75 min Pipe Full Vel 1.8837 fps 1/15/98 3 : 11: 39 pm Barghausen Engineers page 12 QFC\WALGREENS - RENTON, WA STORM DRAINAGE CONVEYANCE CALCULATIONS BCE # 6116 REACH SUMMARY PIPE REACH ID No. P07 From: To: Pipe Diameter: 0. 6667 ft n: 0. 0120 Pipe Length 67 . 0000 ft s: 0. 0019 Up invert : 396 . 9500 ft down invert: 396. 8200 ft Collection Area: 0. 5700 Ac. Design Flow 0. 3666 cfs Dsgn Depth: 0 . 39 ft Pipe Capacity 0. 6220 cfs Design Vel 1. 7535 fps Travel Time: 0 . 64 min Pipe Full Vel 1. 8286 fps PIPE REACH ID No. P08 From: To: Pipe Diameter: 1. 0000 ft n: 0. 0120 Pipe Length 65. 0000 ft s: 0. 0025 Up invert : 396.8200 ft down invert: 396. 6600 ft Collection Area: 1. 8100 Ac. Design Flow 1. 1834 cfs Dsgn Depth: 0. 57 ft Pipe Capacity 2 . 0655 cfs Design Vel 2 . 5714 fps Travel Time: 0. 42 min Pipe Full Vel 2 . 6989 fps PIPE REACH ID No. P09 From: To: Pipe Diameter: 1. 0000 ft n: 0. 0120 Pipe Length : 173 . 0000 ft s: 0. 0024 Up invert : 396. 6600 ft down invert: 396. 2400 ft Collection Area: 2 . 0600 Ac. Design Flow 1. 3466 cfs Dsgn Depth: 0. 62 ft Pipe Capacity 2 . 0512 cfs Design Vel 2 . 6319 fps Travel Time: 1. 10 min Pipe Full Vel 2 . 6803 fps PIPE REACH ID No. P10 From: To: Pipe Diameter: 0. 6667 ft n: 0. 0120 Pipe Length : 128 . 0000 ft s: 0. 0023 Up invert : 397 . 0200 ft down invert: 396 . 7100 ft Collection Area: 0. 2500 Ac. Design Flow 0. 1632 cfs Dsgn Depth: 0. 23 ft Pipe Capacity 0. 6824 cfs Design Vel 1. 5228 fps Travel Time: 1. 40 min Pipe Full Vel 2 . 0064 fps 1/15/98 3 : 11: 40 pm Barghausen Engineers page 13 QFC\WALGREENS - RENTON, WA STORM DRAINAGE CONVEYANCE CALCULATIONS BCE # 6116 REACH SUMMARY PIPE REACH ID No. P11 From: To: Pipe Diameter: 1. 0000 ft n: 0. 0120 Pipe Length 65. 0000 ft s: 0. 0025 Up invert : 396.7100 ft down invert: 396. 5500 ft Collection Area: 0. 6700 Ac. Design Flow 0.4388 cfs Dsgn Depth: 0. 33 ft Pipe Capacity 2 . 0655 cfs Design Vel 1.9819 fps Travel Time: 0. 55 min Pipe Full Vel 2 . 6989 fps PIPE REACH ID No. P12 From: To: Pipe Diameter: 1. 0000 ft n: 0. 0120 Pipe Length : 132 . 0000 ft s: 0. 0023 Up invert : 396.5500 ft down invert: 396.2400 ft Collection Area: 0.8600 Ac. Design Flow 0. 5610 cfs Dsgn Depth: 0. 37 ft Pipe Capacity 2 . 0175 cfs Design Vel 2 . 0857 fps Travel Time: 1. 05 min Pipe Full Vel 2 . 6362 fps PIPE REACH ID No. P13 From: To: Pipe Diameter: 1. 2500 ft n: 0.0120 Pipe Length 78 . 0000 ft s: 0. 0026 Up invert : 396.2400 ft down invert: 396. 0400 ft Collection Area: 3 . 5600 Ac. Design Flow 2. 3297 cfs Dsgn Depth: 0.74 ft Pipe Capacity 3 .8222 cfs Design Vel 3 . 0883 fps Travel Time: 0. 42 min Pipe Full Vel 3 . 1964 fps PIPE REACH ID No. P14 From: To: Pipe Diameter: 0. 6667 ft n: 0. 0120 Pipe Length : 118 . 0000 ft s: 0. 0025 Up invert : 396. 5500 ft down invert: 396. 2500 ft Collection Area: 0. 0900 Ac. Design Flow 0. 0501 cfs Dsgn Depth: 0. 12 ft Pipe Capacity 0.7120 cfs Design Vel 1. 1168 fps Travel Time: 1.76 min Pipe Full Vel 2 . 0932 fps 1/15/98 3 : 11:40 pm Barghausen Engineers page 14 QFC\WALGREENS - RENTON, WA STORM DRAINAGE CONVEYANCE CALCULATIONS BCE # 6116 REACH SUMMARY PIPE REACH ID No. P15 From: To: Pipe Diameter: 0. 6667 ft n: 0. 0120 Pipe Length 78 . 0000 ft s: 0. 0027 Up invert : 396. 2500 ft down invert: 396. 0400 ft Collection Area: 0.2600 Ac. Design Flow 0. 1624 cfs Dsgn Depth: 0.22 ft Pipe Capacity 0. 7327 cfs Design Vel 1. 6005 fps Travel Time: 0. 81 min Pipe Full Vel 2 . 1541 fps PIPE REACH ID No. P16 From: To: Pipe Diameter: 1. 2500 ft n: 0. 0120 Pipe Length 84. 0000 ft s: 0. 0021 Up invert : 396. 0400 ft down invert: 395.8600 ft Collection Area: 4 . 0500 Ac. Design Flow 2 . 6417 cfs Dsgn Depth: 0. 86 ft Pipe Capacity 3 . 4941 cfs Design Vel 2 .9493 fps Travel Time: 0.47 min Pipe Full Vel 2 .9221 fps PIPE REACH ID No. P17 From: To: Pipe Diameter: 1.2500 ft n: 0. 0120 Pipe Length : 151. 0000 ft s: 0. 0021 Up invert : 395.8600 ft down invert: 395. 5500 ft Collection Area: 4 .4200 Ac. Design Flow 2 .8792 cfs Dsgn Depth: 0.93 ft Pipe Capacity 3 .4201 cfs Design Vel 2 .9342 fps Travel Time: 0. 86 min Pipe Full Vel 2 .8602 fps PIPE REACH ID No. P18 From: To: Pipe Diameter: 0. 6667 ft n: 0. 0120 Pipe Length : 130. 0000 ft s: 0. 0020 Up invert : 396. 6100 ft down invert: 396. 3500 ft Collection Area: 0. 2700 Ac. Design Flow 0. 1807 cfs Dsgn Depth: 0. 25 ft Pipe Capacity 0. 6315 cfs Design Vel 1. 4803 fps Travel Time: 1. 46 min Pipe Full Vel 1. 8566 fps 1/15/98 3 : 11: 40 pm Barghausen Engineers page 15 QFC\WALGREENS - RENTON, WA STORM DRAINAGE CONVEYANCE CALCULATIONS BCE # 6116 REACH SUMMARY PIPE REACH ID No. P19 From: To: Pipe Diameter: 1. 0000 ft n: 0. 0120 Pipe Length : 140. 0000 ft s: 0. 0020 Up invert : 396. 3500 ft down invert: 396. 0700 ft Collection Area: 0. 4800 Ac. Design Flow 0. 3166 cfs Dsgn Depth: 0. 29 ft Pipe Capacity 1. 8618 cfs Design Vel 1. 6774 fps Travel Time: 1. 39 min Pipe Full Vel 2 .4328 fps PIPE REACH ID No. P20 From: To: Pipe Diameter: 1. 0000 ft n: 0. 0120 Pipe Length : 130. 0000 ft s: 0. 0020 Up invert : 396. 0700 ft down invert: 395. 8100 ft Collection Area: 1. 1900 Ac. Design Flow 0.8017 cfs Dsgn Depth: 0.48 ft Pipe Capacity 1. 8618 cfs Design Vel 2 . 1616 fps Travel Time: 1. 00 min Pipe Full Vel 2 .4328 fps PIPE REACH ID No. P21 From: To: Pipe Diameter: 1. 0000 ft n: 0.0120 Pipe Length : 132 . 0000 ft s: 0. 0020 Up invert : 395.8100 ft down invert: 395. 5500 ft Collection Area: 1. 5900 Ac. Design Flow 1. 0750 cfs Dsgn Depth: 0. 57 ft Pipe Capacity 1.8476 cfs Design Vel 2 . 3083 fps Travel Time: 0. 95 min Pipe Full Vel 2 .4143 fps PIPE REACH ID No. P22 From: To: Pipe Diameter: 1. 5000 ft n: 0.0120 Pipe Length 29 . 0000 ft s: 0. 0017 Up invert : 395.5500 ft down invert: 395. 5000 ft Collection Area: 6.2000 Ac. Design Flow 4 . 0764 cfs Dsgn Depth: 1. 07 ft Pipe Capacity 5. 0966 cfs Design Vel 3 . 0152 fps Travel Time: 0. 16 min Pipe Full Vel 2 . 9599 fps VI. SPECIAL REPORT AND STUDY RENTON HIGHLANDS SHOPPING CENTER NE 4th ST. and DUVALL AVE. NE - CITY OF RENTON, WA CONCEPTUAL WETLAND MITIGATION REPORT Prepared For: JMR PACIFIC Bellevue, Washington Prepared By: TALASAEA CONSULTANTS Woodinville, Washington November 6, 1997 RENTON HIGHLANDS SHOPPING CENTER NE 4th ST. and DUVALL AVE. NE - CITY OF RENTON, WA CONCEPTUAL WETLAND MITIGATION REPORT Prepared for.• , JMR Pacific 600 - 1081'Ave. NE, Suite 343 Bellevue, WA 98004 Prepared by: Talasaea Consultants 15020 Bear Creek Road NE Woodinville, Washington 98072 November 6, 1997 TABLE OF CONTENTS Page 1.0 INTRODUCTION 1 2.0 DEVELOPMENT IMPACTS ON WETLANDS 1 3.0 MITIGATION FOR WETLAND IMPACTS 1 3.1 Goals and Objectives 2 3.2 Plantings 2 3.3 Habitat Features 2 4.0 CONSTRUCTION MANAGEMENT 3 5.0 MONITORING METHODOLOGY 3 5.1 Vegetation 3 5.2 Wildlife 3 5.3 Water Quality and Hydrology 4 6.0 SUCCESS CRITERIA 4 7.0 MAINTENANCE (M) AND CONTINGENCY (C) 4 8.0 PERFORMANCE BOND 5 9.0 AS-BUILT PLAN 5 LIST OF FIGURES 1. Location Map 2. Proposed Site Plan & Wetland Mitigation Concept APPENDICES A. Wetlands Evaluation and Delineation Report prepared by Watershed Dynamics, Inc. RENTON HIGHLANDS SHOPPING CENTER NE 4th ST. and DUVALL AVE. NE - CITY OF RENTON, WA CONCEPTUAL WETLAND MITIGATION REPORT November 6, 1997 1.0 INTRODUCTION The subject property consists of approximately 8.5 acres located at the northeast corner of NE 4th Street and Duvall Avenue NE in the City of Renton, Washington (Figure 1). A Wetlands Evaluation and Delineation Report was prepared for the site by Watershed Dynamics, Inc. (WDI) in 1995, and has been included with this document as Appendix A. The results of the WDI wetland study were subsequently reviewed by Talasaea in June of 1997 and appear to be accurate. Two wetlands (Wetland A and Wetland B) approximately 0.52 acres (22,913 s.f.) in total on-site size were identified and delineated by WDI as part of their evaluation (Figure 2). Wetland A (12,948 s.f., on-site) extends slightly off-site to the east, while Wetland B (9,965 s.f.) appears to be isolated within the study property. Wetland A is connected hydrologically, via a culvert under NE 4th Street, to an area located off-site to the south which is identified on the City of Renton's Wetland Inventory as Wetland 21 K. According to the City of Renton's Wetland Management Regulations, both Wetland A and Wetland B would meet the definition of a Category 3 wetland. The proposed project consists of the construction of a mixed commercial retail development containing a QFC store and other retail shops. 2.0 DEVELOPMENT IMPACTS ON WETLANDS Wetland A, the higher value wetland on the site, will be preserved following construction (Figure 2). The proposed project does, however, require the filling and grading of Wetland B for a total wetland impact of 9,965 s.f. (0.23 acres). Although approximately 8,165 s.f. of impact to Wetland B will occur as a result of direct fill due to grading, the remaining 1,800 s.f. of Wetland B will be incorporated into the design of the stormwater facility for the site. Following construction, the portion of Wetland B located within the stormwater facility should retain some of the functions it currently provides (i.e., stormwater storage and water quality protection). 3.0 MITIGATION FOR WETLAND IMPACTS Mitigation for the 9,965 s.f. of impact to Wetland B will occur as approximately 9,965 s.f. (1:1 replacement to loss ratio) of wetland creation adjacent to the west edge of Wetland A to form a larger, more diverse wetland system. Although the City of Renton generally requires a 1.5:1 replacement to loss ratio for Category 3 wetlands, this ratio can be reduced if other types of mitigation are provided. Compensation for the reduction of the replacement to loss ratio will occur through enhancement of the stormwater facilities on the site. These enhancement measures will include planting the stormwater storage ponds with a variety of native trees and shrubs to increase their habitat value. By integrating the landscape of the ponds with that of Wetland A and its buffer, it is anticipated that an overall benefit will be achieved. Renton Highlands Shopping Center-Renton,WA Conceptual Wetland Mitigation Report 1 378mit2.rpt-November 6, 1997 Soe Rt wt HE '<Sr i 8 ry NA NE 1� < > S7 I SE 125TH ST w �Ets e r NE w o H S �r o ¢ H ST I ¢ v 1 L c7T �F' 4 > > ET �l +( `yE � � ~ I � :�:.:�.: 1STTM < MtN�S�P ND$OR: L a RENT MI TE Z �I ST FC U DALE NE.. CAL I r N co 11 x A� .: HILpS N IT _ ` NE ■ cocL E 4TN I SE 128TH ST s =g° 4oS 1129TH I I m S SE 131ST 3T �a W a'I QI NE — — NE �� / NE �NOD .T USE 'L� __ SE 12ND QST NIf R( '7CJ(CTH1.137RD ST 7 1/ ohC UHT LEISURE E 7eiNOLIVET 16 ESTATESPL I� 1357H I S SrCfHETERY HHP `' p� t E 35THST NO P' SE 136TH ST1 100 a F S TE PL"1i UNTON = SE ld HHPSE 4RpSE5TH S " Q 139TN PLSE ,as �JFyW KV SE o Jr�E 141ST <1(ITH PL W SE R F r° q ST 4 �- o JF r.. t f F `f Y t 142ND ST <- :SE 142NO ST 'TH CT H4PC « ► v S7J y^s`A I T�� S�-'w00 l�r _ SE 142N0- ., t ROAO SIDE aP S s 7 t $LIA SF ♦T" ' T r ^& PL Ems .(^" e : SE..143RD a 144T < ST PL q $E 145T t s `�°DH r MA P L EWOO D SE AR _ F �O R s j" i _- <Ef' 4y� 'Y4lk � ty s� yyy d of S P 22.- cf.DaR W o�P sE 5t JN s s S W s TAN RIVER Wr �$E��� ��Y 16•Cr h two � �� � � � �\J�Jl � � 1 ' PARKr• 1 o~i y STN: P 1 sT MAPS iN CT s �> <x aTN ,� 5 "< �' �= JE . S 'y RD 1 T,t Fy�E 1BT �=tr t' i SF 157TN St h tN �^ y.�aT ➢r9 ST % N /�PJf. S \.i`E TlFFANr all "'N t7,SE 19 ij'l p(\vARK- ryRwlsE y�ls ter" , JF p(155T� S k'Y`sF yam. jl �k c, d aykN �1leS fT't [T'��, 35 C 2 x •i ^ ti E`YS6)N_�. /CSBT S(R .; N R'� r.„• ,T. L SS SE 215T ST F ,fSf vWi .v<$T ae ` -��'t� u ""!�F�"+!^ Q+,� 1S9T ST FA I RW 0 0 q SE 158TH (SF +F� 1607E ST �` �159TN ►L W c ST <SE I IST ST', 6ry SE 'ST 159TN ^ Pt N 161 T I% SE 160TH R d S 1595� 1 62ND'< i ST S I61ST PL. R 1 W% SE 161 ST►L 6'.SF 160TN ,� A, S� _ w SE 163RD ST o ^16 1 TH ST N f2 PARK N ;, 161 n `r �f islst� �� W 30900 SE 164TH ., ST - 64 N„ a _ p PD y j f x p( �h $E 162ND PL H 11100 , ti ->� '^ SE 1657H �6r 117�5 165TH < sE W J2.��, sr 1� 16srH J SE 164TH S sT �e�,�N`� 16�0 ST < h $T `��'S lxrw Si�d ��JF SE 166TH ST T Sf� ST `JF ls5 N ST1 H ;&167TH S1 < SE a 166TN Pl '+S�' T Jr "'� SC 167TH ST p o N 7F$ FAIRWppp ,n $ S�1ZrJ�S ]671H^ Jf r CHARLES A G 'F' - 4l V�' 65TN Jr m W SE 16TT IT 8 1RT , ,,. ■C1N08ERGH AS 1, North SOURCE: The Thomas Brothers Guide, Gommerciol Edition Igg5 FIGURE I: Location Map t1 150 TALASAEA Renton Highlands Gtr. CONSULTANTS N.T. I FZesourc-c 4 En,Ircr-imciicai Purring Renton, Ha5hington DATE 15020 Boor G-eek Roc"Northec6t -I6-q�i H,od"lla,Ha h"tan 98012 Bus(206)661-1550-F< (206)661-15414 REYI� r7w tiJ j OAND I DATE L 1`3T OF PLANT SPED I ES - I TREE5/LARC-7E SHRUBS 1 ( / 5GIENTIFIG NAME GOMMON NAME SIZE ` v;,� '- AGER GIRGINATUM VINE MAPLE 5'-b' ht., 5 stem min. 1-5" cal. min. FRAXINUS LATIFOLIA ORE60N ASH 8'-10' ht., 1 ONDS PLANTED }iOLODISGIJr, D15GOLOR OGEAN5PRAY 5 gal., 5 stem min. ( 4 x J�NATIVE 5PECIE5 ANCHOR 2 C2,I=G ANCHOR OEMLERIA GERA5IFORMI5 05015ERRY 5 gal., 5 stem min. POPULUS TREMULOIDES OUAKIN6 ASPEN 8'-10' ht., 15" cal. min. 1 ham'" 'E4i...Y:?'7'.�F.�SaS.= i WAY . 2 s.c P5EUD0T5U6A MENZIESII DOU6LA5 FIR 5-6 ht., full d bushy 5ALIX 5PP. WILLOW 5 gal., 5 stem min. Tl IJJA PLIGATA K RED GEDAR 5'-b' ht., full 4 bushy SHRUBS 5GIENTIFIG NAME _ COMMON NAME SIZE "`' ". 6AULTHERIA 5HALLON SALAL 1 gal., 24" ht., 3 stem min. MAHOMA AGUIFOLIUM TALL ORE60N6RAPE 2 gal., 24" ht., 3 stem min. till RIBE5 5ANOUINEUM RED CURRANT 2 gal., 24" ht., 3 stem min. J...-. R05A PISOG LU ARPA CSTERED R05E 2 gal., 24" ht., 3 stem min. \� ga65 5F 5YMPHORIGARP05 ALBU5 5N0J,-BERRY 2 gal., 24" ht., 3 stem min. ENHANCED HETLAND i: t - 15,500 5F - PLANTED WITH NATIVE 5PECIE5 z; zz �� , YETLAND MITIGATION AREA - 12A21 5F • 'f J y y � . - ( %'' W i W W GENERAL NOTES , I. THIS IS A GONGEPT PLAN ONLY AND SHALL NOT BE USED FOR GONSTRUGTION PURPOSES. KA" W 2. 51TE PLAN 1^!AS PREPARED BY BARGHAUSEN CONSULTING ti ENGINEERS, ING. - GATED II/4/q-7. `.',', ,', W W W W y 3. HYDROLOGY FOR (TREATED WETLAND AND WETLAND A 1 ' ' ' ' I SHALL BE SUPPLIED BY TREATED AND DETAINED i I �/�,',� I y• 5TORMWATER RUN(-FF. THE FINAL PLAN HILL DEPIGT 4 % OUANTITIES. / ,' •Y •L •Y I Y W 41 w-----------_--------------- --------_._._.__-- -- N E. 4th 5T 3�(S E. 128th STD . _--- TREATED 5TORM- .. --- __ North INTO htE'TLAND AREA ;,• �s1eN oRnr►+ FIGURE 2: Proposed 51te Plan 4 50, JA 150 TALASAEA Wetland Mitigation Gonr-ept "LE 1 CONSULTANTS Renton Highlands Gtr. - 0 40 80 160 Re 15020E d Environmental Plonnitheostnc� Renton, Washington DATE rt t 2 15020 Bcar Greck Road Northeast I 1-6-e{ 1 hboll"Ile.Woshhgt 95012 REVISED EN,,(20 6)b61-1550-Fox(206)bbl--1549 Additional compensation for the reduced replacement ratio will include preservation of the significant upland trees located in the mitigation area. As depicted on Figure 2, the mitigation area is 12,821 s.f. and only 9,965 s.f. will be created wetland. The remaining area will be preserved upland trees (primarily Douglas fir). The final plan will depict the location of the trees and how the proposed mitigation will be located around most of them. Preservation of these trees as "upland islands" increases the habitat value of the overall wetland system and provides better protection to the existing wetlands. In addition, the 15,500 s.f. wetland buffer (25' minimum) will be enhanced with dense understory vegetation (e.g., tall oregongrape and rose) to create a stronger physical barrier. 3.1 Goal and Objectives Goal: Create a replacement wetland and enhance the stormwater facilities on the site to compensate for impacting 9,965 s.f. of wetland (Wetland B). Objectives: • Create 9,965 s.f. of wetland adjacent to Wetland A to create a larger, more diverse wetland system. • Increase plant species and structural diversity throughout the created wetland and its buffer, as well as the stormwater facilities for the project. • Incorporate habitat features (e.g., snags, downed logs, and other woody material) into the created wetland and its buffer. • Remove and control invasive and exotic species in all wetland and buffer areas. • Simulate pre-construction wetland hydrology by supplying the existing and created wetland with a portion of the previously detained roof-top runoff and treated stormwater from the site. 3.2 Plantings The candidate plant species used in the mitigation concept were chosen for a variety of qualities, including: adaptation to specific water regimes, value to wildlife, value as a physical or visual barrier, size, pattern of growth (structural diversity), and aesthetic value. These native plantings will increase both the structural and plant species diversity within the wetland and buffer areas, thereby increasing the area's value to wildlife. 3.3 Habitat Features Snags, stumps, and down logs will be incorporated into the mitigation area to provide ecologically important habitat features. These habitat features will be relocated from areas on the project site that will be cleared for development. Snags provide both perching and nesting sites for a variety of native birds. Cavity nesting bird species, such as chickadees and woodpeckers could be expected to utilize such features. Down logs provide the slow release of nutrients as the wood decays, and also provide cover for amphibians, small mammals, and other wildlife. Other structures to be installed for further enhancement of wildlife habitat value include bird nesting boxes. Renton Highlands Shopping Center-Renton,WA Conceptual Wetland Mitigation Report 2 378mit2.rpt-November 6, 1997 4.0 CONSTRUCTION MANAGEMENT Prior to commencement of any work by contractors in the mitigation areas, the clearing and construction limits will be staked, grade staking will be completed, and fencing will be installed around all existing vegetation to be saved. A pre- construction meeting will be held at the construction site to review and discuss all aspects of the project with the selected contractor. A wetland biologist will supervise plan implementation during construction to ensure that objectives and specifications of the mitigation plan are met. Any modifications to the design that may be necessary due to unforeseen site conditions will be jointly approved by the City of Renton and the wetland biologist prior to their implementation. 5.0 MONITORING METHODOLOGY As required by the City of Renton, the monitoring program will be conducted for a period of five years, with reports submitted to the City according to the following schedule: • quarterly for the first year following construction • annually (at the end of the growing season) for the second through fifth years 5.1 Vegetation Permanent vegetation sampling points or transects will be established at selected locations to incorporate all of the representative plant communities. The same monitoring locations will be re-visited each year with a record kept of all plant species found. Vegetation will be recorded on the basis of relative percent cover of the dominant species within the vegetative strata. All monitoring will be conducted by a qualified biologist. Photo-points will be established from which photographs will be taken throughout the monitoring period. These photographs will document general appearance and progress in plant community establishment in the mitigation and restoration areas. Review of the photos over time will provide a semi-quantitative representation of success of the planting plan. Monitoring and photo-point locations will be shown and described in the first monitoring report. 5.2 Wildlife Birds, mammals, reptiles, amphibians and invertebrates which are readily observable (either by direct or indirect means) will be identified and recorded in the wetland and buffer areas. Direct observations include actual sightings, while indirect observations include tracks, scat, nests, song, or other indicative signs. The kinds and locations of the habitat with greatest use by each species will be noted, as will any breeding or nesting activities. Renton Highlands Shopping Center-Renton,WA Conceptual Wetland Mitigation Report 3 378mit2.rpt-November 6, 1997 5.3 Water Quality and Hydrology During each monitoring event, an assessment will be made of the water regime within the mitigation area to ensure that proper hydrological conditions exist within both the wetland and its buffer. General observations will be made of the extent and depth of soil saturation or inundation. Water quality will be assessed qualitatively, unless it is evident there is a serious problem. In such an event, water quality samples will be taken and analyzed in a laboratory for suspected parameters. Qualitative assessments of water quality include: 1. oil sheen or other surface films, 2. abnormal color of water or odor, 3. stressed or dead vegetation or aquatic fauna, and 4. turbidity. 6.0 SUCCESS CRITERIA Success of plant establishment within the mitigation area will be evaluated on the basis of both percent survival and percent cover of desirable species. Undesirable species include exotic and invasive species such as Scot's broom, Himalayan and evergreen blackberry, reed canarygrass, purple loosestrife, morning glory, Japanese knotweed, and creeping nightshade. For woody planted species, success will be based on at least an 85% survival rate of all planted trees and shrubs, or at least 80% cover of equivalent recolonized native species, by the end of the five-year monitoring period. Success for herbaceous species will be based on an 80% cover of desirable plant species by the end of the 5-year monitoring period. Undesirable plant species will be maintained at levels below 20% total cover. Removal of these species will occur immediately following the fonitoring event in which they surpass the 20% maximum coverage. Removal will occur by hand whenever possible. No chemical treatment will be employed without prior approval by the City. 7.0 MAINTENANCE (M) AND CONTINGENCY (C) Established performance standards for the project will be compared to the monitoring results in order to judge the success of the mitigation and restoration project. Contingency will include the items listed below and would be implemented if these performance standards are not met. Maintenance and remedial action on the site will be implemented immediately upon completion of the monitoring event (unless otherwise specifically indicated below). • replace dead plants with the same species or a substitute species that meets the goals and objectives of the plan (C) • re-plant areas after reason for failure has been identified (e.g., moisture regime, poor plant stock, disease, shade/sun conditions, wildlife damage, etc.) (C) • line wetland areas with impermeable material where hydrology is deemed to be insufficient to support the desired wetland plant community. Where Renton Highlands Shopping Center-Renton,WA Conceptual Wetland Mitigation Report 4 378mit2.rpt-November 6, 1997 appropriate, liners may be installed immediately upon completion of grading to increase probability of wetland success (C) • irrigate with a temporary system for at least one full growing season following plant installation (M) • after consulting with City staff- minor excavation, as needed, to correct alterations of surface drainage patterns (C) • remove/control weedy or exotic invasive plants (e.g., Scot's broom, reed canarygrass, Himalayan blackberry, purple loosestrife, etc.) by manual or chemical means approved by the City of Renton. Use of herbicides or pesticides within the mitigation area would only be implemented if other measures failed or were considered unlikely to be successful, and would require prior agency approval (C & M) • clean-up trash and other debris (M) • clear or repair trash racks, culverts, etc. (M) • selectively prune woody plants to meet the plan's goals and objectives (e.g., thinning and removal of dead or diseased portions of trees/shrubs) (M) 8.0 PERFORMANCE BOND A performance bond will be posted with the City of Renton by the property owner for the cost of replacement of plantings and the 5-year monitoring plan to assure the success of the mitigation and restoration plan. The bond may be released in partial amounts in proportion to work successfully completed over the 5-year monitoring period as the applicant demonstrates performance for implementing the conditions of the plan. 9.0 AS-BUILT PLAN Following completion of construction activities, a set of"as-built" plans for the wetland mitigation area will be provided to the City of Renton. The plans will identify and describe any City-approved changes in grading, planting or other constructed features in relation to the original approved plan. Renton Highlands Shopping Center-Renton,WA Conceptual Wetland Mitigation Report 5 378mit2.rpt-November 6, 1997 APPENDIX A Wetlands Evaluation and Delineation Report Prepared by Watershed Dynamics, Inc. l � IETLANDS EVALUQTtO.N AND DELINEATIQN REPO RT )Y�a ^t•1���h-•s�� ySt��'(i • '•RR s./1 yf K+.%. 2' J,Y}, 'FL.� 2-J, �-v c- / .k 1• !N!Y h J.,{ + } M y f I`I A .3 A \ _31 .o. - 7. �Z;t Yr!•T"�' h -r �".1 •6 F {r M t C'it l H1.. F J+'�`�{ r•�3i� i1 ra {�� .h• ry::.��rs'�'�.'x'^t•P-... D�' xY.lr ��`,i•,x t ,,.�"` r�� � }S• y�.�J=` •J t c ik p p j"a, l ,ERT�`t- ' C, �+'YC"-; ' a?.� SIrL7Db� .. f/ �Ta t t .A^ .t� � 4 -7a�.�1t'T ftl�3: Y $Yi 7 4•Tf�j„F,-f •rx�n aYt »' 1. /�.rPs a^tt, }.,ems t 7 if`str t r t f`aT 1•'- Yti ^t .y {' {a.FY{T^1�.,, r.�.�.,ck$�i�y �k .a y>'"•w :'ys"; f.`.r� �;y:.• C c�'4 >✓ Mr." 1tC(pSH�NTQ f ;},G2� � ::+ s-jrt� nY ti 7�„L�� Fir,�v � y- ji r �5 a r a, hs - �t ,a'J. •� .C: � -r !ri jR, r c ♦< � Y r � v" ti.,i�l ttt .x �2✓�_�S v�`s 1 � c '*�C?+' 4�� � 4 r <,u�}� �i �� +! •° � l�jtKt .Pc 5 k7��� ��5 `^�+ ..9'G1 C"1:JEY1�.�t���1�t�•� 9" -+r`i � ar ..a' Mr _ :':z�"* � - r.•i•a:.�wn.r.,�i.'...�:a'o�.ly»:.r'�n..u.e..war`xl�+�.:�..!.+.Ja�.�+sa.ea.ew��.��•ru - �4,�fi ir`.�.v�t'�'fit. ^'.r�tc:•SSrLa.etc'^t'�i�!.:r.��s'�.ai�cC�i:id'�..T.Y.a"`..°ti•G:+.'TE�kt?SC�TGL+ty::� '.`!\'S,Lb�fe3`rJ.—'�.nmt�a`�`-rt�`"s-''�c.,�•� �Y-:�S•,Q�a �'�e� rr�t�-���.�+i f4`�4[c exl�l"+�� v. �,}J�+`�` '�`'��i�. � ' Y� 7"F�y� 4 a�gG.!•A,.�1''+Yv�,l.rt. [�'c^�{S't y c� t��Jr �••.c,�.� i`�y,'�. a�` ���' ''�.sr' a 1 j�'Y is ,�'� �(� a+'! tiu}a�'k�!w�...RS71au�M.�'`�'�c•.s�`..s'��W.'•cal.�r�"' 11.si.':F+<�'S.6��.-i$�k��.�.``,tr�"afi�"c "•ad�7rhr::1�,.�.s��is��'�L` .�.-�'h` i�+�a�r• •�"`'�"rt'."i WATERSHED DYNAMICS, INC . EXECUTIVE SUMMARY The Tibbott Project Site is located within the City of Renton, King County, Washington. Watershed Dynamics, Inc. (WDI) was retained to provide an evaluation of wetland characteristics following the procedures outlined in the Federal Manual for Identifying and Delineating Jurisdictional Wetlands (1989 manual). Two wetland areas (Wetland A and Wetland B) approximately 0.52 acres in total size (22,9130 sq. ft) were identified and delineated within the project site. These wetlands appeared to meet the following United States Fish and Wildlife Service wetland classifications: Wetland A -Palustrine, Forested, Seasonally Flooded (PFOC) Wetland B - Palustrine, Scrub/Shrub, Seasonally Flooded (PSSC) Wetland A (12,948 sq. ft onsite) extended slightly offsite to the east. Wetland B (9,965 sq. ft onsite) appeared to be isolated within the study property. Wetland A was connected hydrologically, via a culvert, to an area located offsite to the south which is identified within the City of Renton Wetlands Inventory as Wetland W21 K. An assessment of the onsite wetland using City of Renton Wetland Management Regulations (Ordinance #4346) identified both Wetland A and Wetland B as meeting the definition of a Category 3 Wetland. This categorization is due to the degree to which the wetlands have been impacted through past and ongoing land use management practices which include ditching, outlet modification, and soils compaction. A Function and Value analysis of each wetland resulted in the assignment of a rating of Low to Medium for Wetland A and a rating of Low for Wetland B. The City of Renton regulates activities in and around wetland areas Such regulations require that an undisturbed native vegetation buffer be placed along the upland side of the identified wetland areas The standard City of Renton protective buffer width for a Class 3 Wetland is 25 feet as measured perpendicular to the wetland edge d TABLE OF CONTENTS EXECUTIVESUMMARY........................................................................................................ i TABLEOF CONTENTS..................................................................................................:...... ii ACKNOWLEDGMENT........................................................................................................... 1 INTRODUCTION.................................................................................................................... 2 WETLANDSTUDY PURPOSE.............................................................................................. 2 PROPERTY SITE DESCRIPTION ......................................................................................... 2 WETLANDS EVALUATION AND DELINEATION REPORT.................................................. 3 BACKGROUND INFORMATION ........................................................................................... 3 Review of Prior Resource Mapping........................................................................ 3 U.S. Fish and Wildlife Service .................................................................... 3 KingCounty................................................................................................. 3 Cityof Renton.............................................................................................. 3 ProjectSite Soil Types................................................................................ 3 ONSITEANALYSIS...............................................................................................................4 WetlandSurvey Methods ........................................................................................ 4 FieldObservations .................................................................................................. 4 Vegetation.................................................................................................... 4 Soils................................................................................................. WETLAND DETERMINATION............................................................................................... 6 Comparison of Wetland Determinations using 1987 and 1989 Methodologies ... 7 WETLAND FUNCTION AND VALUE ASSESSMENT........................................................ 7 FUNCTIONAL VALUATION...................................................................................... 7 ONSITE WETLAND VALUATION..........................................................................................9 ....................................................................................4M _L_ L =................................................................................................• Emam" ......................................... ............................. APPENDIX A 1989 FIELD DATA FORh1S .......................................................................... 22 APPENDIX B PLANT SPECIES LIST................................................................................. 23 APPENDIX C WETLAND VALUATION FORM ................................................................... 25 ACKNOWLEDGMENT The wetland delineation and report has been completed by Watershed Dynamics, Inc. Prior to extensive site planning, this document should be reviewed and approved by permitting agencies. Wetland boundaries, wetland classification, proposed buffers, and conceptual mitigation should be reviewed and approved by City of Renton Environmental Review Staff. The above consultants have provided professional services that are in accordance with the degree of care and skill generally accepted in the nature of the work accomplished. No other warranties are expressed or implied. The consultant is not responsible for design costs incurred before this document is approved by the permitting agencies. David W. Risvold Project Ecologist Watershed Dynamics, Inc. INTRODUCTION This report details the culmination of activities and onsite evaluations undertaken by WATERSHED DYNAMICS, INC. to complete a wetland evaluation and delineation on an approximately 8.5 acre parcel located northeast of the intersection of N.E. 4th Street and Duvall Avenue NE, within the City of Renton, Washington. SE 1/4, SE 1/4, SW 1/4, Section 10, Township 23N, Range 5E (Figure 1). Wetlands mean those " lands transitional between terrestrial and aquatic systems that are inundated or saturated by ground or surface water at a frequency and duration sufficient to support and, under normal circumstances, do support a prevalence of.vegetation typically adapted for life in saturated soil conditions." (City of Renton Wetland Management Regulations, Ordinance #4346) WETLAND STUDY PURPOSE The PURPOSE of this study was to complete a scientific inventory and evaluation of wetland areas within the project site. This report is suitable for submittal to federal, state, and local authorities for wetland boundary verification. PROPERTY SITE DESCRIPTION The Tibbott property site (Site) is comprised of four generalized topographic features (Figure 2). These features consisted of 1) a conifer dominated, generally-flat, upland forest community which comprised the majority of the Site, 2) a paved area located along the southern Site boundary, 3) previously cleared areas within the northwest portion of the Site which were dominated by deciduous tree, sapling and shrub vegetation, and 4) two depressional areas located generally along the eastern Site boundary which were dominated by deciduous tree, sapling, and shrub vegetation. The dominant vegetative community onsite was a Douglas-fir (Pseudotsuga menziesii), salal (Gau/theria shallop) upland forest community. A sub-dominant community was located in two depressional areas located generally along the eastern Site boundary. Vegetation in these two areas included black cottonwood (Populus trichocarpa) trees, Oregon ash (Fraxinus latifolia) saplings, and a sparse to dense Douglas spiraea (Spiraea douglash) shrub component. Three additional distinctive vegetative assemblages identified onsite included an ornamental tree and shrub community along a portion of the paved Site feature and deciduous dominated shrub and sapling communities (Spiraea and willow (Salix spp.)) found a) in association with the ditchline 2 Tibbott Final Welland and Mitigation Report WetMitt.doc lilt 3ti�I�i a.Ar� ;1b.S` � tt �� 'fit. ;/•1 'fiaR���', ,. ,t�� Pt'�'�"rf� �� . �?iPel'•3� 'tj�'� i, fit. ! , �.,���•• i �, y 11.{�21Y 1 ,,� i,w�i4'� �hr,�•;}i�)+�.�'`�k.�,flF�'hry�,���A+:p��•1'�iir f� rFjG,� r'+i �N�. i�(?�ti' ► �Gr �gp�� •{�:, ; t '° �+�'� '.t'`4:•'Id {�ti.• tifi,�''�: �a .�e k ;�c � WWI > k� ..J{{'�. "Q'� 1�+�'�• �4 � ���5:1 � '•t1.61•'• . .� art ..,.� � + •1� r '� J • �!,I r� ,v' :til 'Oil, A o,r.• r a .;�yt.: , � `i � '`ii'$;y?_ +` ,�. fir• �� � . ti `r. �� a tefl'''a •.' � {� �, •'�t )F,'• ;,R M Adr, � tf'! �. ra f,} �a {.�'� g r ��.* n ;., ,P)t + .� Ft?i: iu,att r`7�►�s t '+ ri� 14 �1• ;�� , i r �`,�...Rrq� •, :lit Jl �r,•f,�� is;���;. � 1�yl,.�h��Myi �Ir.���}'l��f��t �,1 S � � ' -�;a. �Lr `� �� ( •51��"'., �11`�"� ..1Z, .:�+1•;'+1�7P��r"�"'4i"!'•'�� 1�"t��,�'t`i+(, .s� • tit, yyrhT 11`1-�� �.•: �.r •7y ,.Pitt" itt" Offsite residence and access corridor 0 H ch("rr� SS4.02 Pr o p crty Boundary IDeciduous Plant Community Depressionat Areas W Conifer W r Dominated Area Okch6ne z / U � Z Access Road aPaved Area K J J :D Ornamental Plants I NE 4th Street OttchOne FIGURE 2. Site Features Map WATERSHED DYNA. CS not t0 scale uburn Wcy R Su11a F ( ) WA 99002 ����Aubu-, along Duvall Avenue NE, and b) in previously cleared areas within the northwest portion of the Site. WETLANDS EVALUATION AND DELINEATION REPORT BACKGROUND INFORMATION Review of Prior Resource Mapping U.S. Fish and Wildlife Service The National Wetlands Inventory Maps for the Site vicinity were reviewed prior to onsite evaluations. No wetlands were identified within the Site using this reference source (Figure 3). King County The Sensitive Areas Map Folio was reviewed prior to onsite evaluations. This reference source did not identify any wetland areas within, or immediately adjacent to, the Site. This source identified King County Wetland #150 - Lower Cedar River, as being offsite, east of the Site (Figure 4). City of Renton The City's Wetland Inventory process has identified three wetland areas adjacent to, but not associated with, the Site (Figure 5). These wetlands are identified as W-20 (to the north), W21 K (to the south), and W27 (to the southwest). Project Site Soil Types The project site soil types as listed in the "Soil Survey of King County Area, Washington" (U.S. Department of Agriculture, Soil Conservation Service, (November 1973) (Figure 6) are: • Alderwood gravelly sandy loam - 6%-15% slopes (AqC): This soil series is moderately well drained and is found in uplands. A typical pedon of Alderwood soils is dark brown (10YR 4/3) gravelly sandy loam from 2 to 12 inches. The Alderwood series is not considered to be a Hydric soil in King County. • Everett gravelly sandy loam - 6%-15% slopes (EvB): This soil series is somewhat excessively drained and underlain by very gravelly sands at depths of 18"-36." A typical pedon of Everett soils is dark brown (7.5YR 3/4) gravelly sandy loam from 1.5 to 17 inches. The Everett series is not considered to be a Hydric soil in King County. 3 Tibbott Final Wetland and Mitigation Report WetMitt.doc r'..'.•S�f �i•'i ii�1� if1 ��i�-J�'iz� t LM��[1 . . cf-nrs��v''` ��a '.✓'�'?y Olt 7.07 �.., '/��.'•' 1. y$Ml�`��J��� a�� �`.� -—���..1� .ems•, .' � � t ��_' � �,.,.c��`'• t yam:"' `..�.t .1 t+ - �.��• •j,, f��=� 1,- = �1�,• \. PROJECT SITE 14 Wetlands 0 I _ wets.t,d. D urva m i s h openWd.t r I 1 l� 1I 'FIGURE 4. Kin �iQUnt WATERSHED DYNAMICS g y Wetland 1833 Auburn Way K Su11� F Inventory Auburn WA 9Boo2 i I <I j . VV I biK W— ' .W17K —26 "PROJECT SITE W 1 8 K W 27� 1 z CEME W21 K I I I S- 25 ' i , W-48 S-21 ig r------ l , L S-24 w-2- W29.K -� W30K S-22 S -23 - =IGURE 5. City of Renton WATERSHED DYNAMICS 1833 Aul urn Wcy f�,.s,,, F Wetland Inventory AuSurn Wa 98002 LLI to ww .... .. y .-.---...-i,......... �, I .. 1 1 a41 LU •��\�,�', . ;`r ,\- L.., � i �• �4`,,. ,' '/fir/ V ONSITE ANALYSIS Wetland Survey Methods Specific onsite wetland evaluation for the Site centered on the onsite evaluation of the established three criteria for wetland delineation as outlined in the Federal Manual for Identifying and Delineating Jurisdictional Wetlands (1989 Manual). Completed on April 17, 1995, the objective of this evaluation was to define and delineate areas within the project site that meet the established criteria for wetland identification. The onsite delineation was performed utilizing the Vegetative Unit Sampling Procedure as defined in the Intermediate On-site Determination Method of the 1989 Manual. This procedure involves sampling plant communities along established transects to determine wetland boundaries. At established points along the transect observations were made as'to the primary plant species within the plant community. Observations of vegetation communities in those areas which were cleared were made using adjacent non-disturbed vegetative communities. Soil characteristics and indications of hydrology were also made as needed. Field data sheets are provided in Appendix A to this report. Evaluation of the Site was also completed using the Level 2 Routine Delineation Method for areas over 5 acres as specified in the 1987 Corps of Enaineers Wetlands Delineation Manual. The resultant transitional boundary between wetland and non-wetland was marked in the field with numbered and flagged 4-foot wooden stakes or on flagged woody vegetation. This transitional boundary was then identified on the project site plan. FIELD OBSERVATIONS The Site was generally flat, with a very slight slope towards the south and east. A shallow depressional corridor was present in the southeast corner of the Site as well as within an area located generally along the eastern Site boundary. Onsite drainage appeared to be directed through the Site in a generally southern direction. Vegetation Site-specific investigations identified one dominant plant community and several sub- dominant plant communities within the Site. The primary plant community found throughout the majority of the site was comprised of a Doug las-fir/salaI upland forest community. This assemblage is considered non-hydrophytic (i.e. non-wetland) and is 4 Tibbott Final Wetland and Mitigation Report WeWdl.doc J typical of well drained upland areas in Puget Sound. A second non-hydrophytic plant community consisted of introduced landscape plants and shrubs found along and within the periphery of the Douglas-fir forest, adjacent to the paved Site feature. Several areas were identified which were dominated by plant species typically considered to be hydrophytic. One such area was located within the southwest corner, and along the western boundary, of the Site and was associated with the roadway ditch along Duvall Avenue S.E. This area contained dense stands of spiraea and willow saplings, and also contained Scot's broom (Cytisus scoparius) and introduced erosion control seeded grasses. A second area of hydrophytic plants was located within the northwest portion of the Site. This area had been logged many years past and was dominated by decidous shrubs and saplings such as black cottonwood, willow, elderberry (Sambucus racemosa), indian plum (Oemlaria cerasiformis), and spiraea. Two other areas dominanted by deciduous vegetation were two depressional areas that were situated generally along the eastern Site boundary and within the southeast corner of the Site. These areas contained species such as black cottonwood, Oregon ash, spiraea, and slough sedge. SOILS (The location of soil test pits is included in Figure 7) Site-specific analysis identified both hydric and non-hydric soils within the project Site. Hydric soils are typically defined as soils that are saturated, flooded, or ponded long enough during the growing season to develop anaerobic conditions within the upper horizons. A Sample Plots (SP#) SP4, and SP10 through SP14 were located within the area dominated by hydrophytic vegetation and exhibited a soil matrix color of black to very dark brown (10YR 2/1 - 3/2) at 10 inches - or below the A horizon. Soil texture was primarily silty loam. Yellowish brown (10YR 4/6) mottles were present in several samples. Sample Plots SP1 through SP3, SP5 through SP9, and SP15 through SP17 were observed to exhibit non-hydric soil characteristics. The soil matrix color was primarily very dark brown (10YR 3/2) to dark yellowish-brown (10YR 4/3) and had a soil texture of sandy loam to gravelly sandy loam. Redoximorphic features such as gleyed layers, mottles, and concretions, were not observed in these sample plots which exhibited the general character of the Alderwood gravelly sandy soil series. 5 Tibbott Final Wetland and Mitigation Report WetMdl.doc HYDROLOGY Wetland hydrology in the Site appeared to be provided by a seasonally high water table and stormwater runoff from higher elevation areas within, and to the north of, the Site, as well as from roadway stormwater runoff from Duvall Avenue NE and NE 4th Street. Indicators of wetland hydrology included soil mottles, soil saturation, wetland drainage patterns, sulfidic odor, and visual evidence of ponded water. The two onsite depressional areas appeared to be a vestige of a larger drainage corridor, a portion of which may historically have passed through the Site from north to south. Based upon a review of the topography of the Site vicinity, it appears that the majority of the larger drainage corridor historically bypassed the Site to the west. This remains the case at -present as offsite land management, commercial, and retail development activities have resulted in the active management of area drainage patterns. Drainage which may historically have contributed to Site hydrologic support is presently directed away from the Site, towards the southwest, via culverts under Duvall Avenue NE. WETLAND DETERMINATION Based on the wetland delineation criteria established in the 1989 Manual and onsite analysis, two wetland areas were identified within the Site (Figure 7 and Attachment A - survey map). The wetlands were generally located along the Site's eastern boundary and within the southeast corner of the Site. Both areas appeared to be hydrologically supported by stormwater runoff and a seasonally high water table. The wetland areas were defined by the documentation of hydrophytic vegetation communities, hydric soils, and wetland hydrology criterion. The onsite portion of Wetland A was surveyed and found to be 0.29 acres in size (12,948 sq. ft). This wetland appeared to extend offsite to the south via a culvert under N.E. 4th Street. Wetland A was dominated by a forested plant community dominated by black cottonwood and exhibited the classification of a Palustrine, forested, seasonally flooded/saturated (PFOE) wetland following the procedures defined within Classification of Wetlands and Dee water Habitats of the United States (Cowardin et al. FWS/OBS-79/31). Wetland B was surveyed and found to be 0.23 acres in size (9,965 sq. ft). Wetland B was dominated by a scrub-shrub plant community dominated by spiraea and salmonberry. Wetland B exhibited the following classification following the procedures defined within Classification of Wetlands and Deepwater Habitats of the United States (Cowardin et al. FWS/OBS-79/31). Palustrine, scrub-shrub, seasonally flooded/saturated (PSSC)* 'The upland periphery of Wetland B was vegetated by a Douglas-fir forest community but, the aerial extent of coverage of the fir trees was not considered sufficient Ci.e. z20%) to warrant the classification of Wetland B as "Forested." . 6 Tibbott Final Wetland and Mitigation Report WelMilt.doc Offsite residence and access corridor D'tt ch li ne -5,P 1 ProPErty Boundary General Direction SP14 of site Grainage /WETLAND B I c 1 _- --- > CO Depressionaf Areas Q to SP,30 1 SP,2 ^�' > / ® SP9 Dttchllne p SP18 SP8 SPI ® SP10 ® SP6 �tl sP11 SP16 r ®sP4 i WETLAND A ®SP17 SP3 ® SP1 J ( 2 Z\ SP2 f _-- NE 4th Street Ditchline SP# = Sample Plot Locations FIGURE 7. WATERSHED DYNAMICS ' 1633 Auburn Wcy tL SAr F Conceptual Site Wetland Map Auburn WA 98002 i Wetland A and B appeared to have once been part of a continuous wetland corridor (based upon their landscape position relative to each other and the offsite wetland areas) which likely extended offsite to the north and south. Based. upon our field reviews, both Wetland A and B have been substantially impacted through commercial and residential development within the Site and the surrounding basin. The commercial and residential development which has taken place on all sides of the Site has resulted in the alteration of Site (and adjacent area) hydrology, ive abundance and composition, and soil compaction. A large multi-phase residential development under construction to the north of the Site has resulted in the diversion of surface water towards the southwest, under Duvall Avenue NE, away from the Site. The construction of NE 4th Street along the southern boundary of the Site, and the associated ongoing maintenance of that roadway ditchline, has altered Site drainage patterns and resulted in untreated roadway stormwater runoff intrusion into Wetland A. Additionally,'past land use activities onsite (such as historic logging) have altered Site hydrology through soil compaction and alteration of native vegetation. Comparison of Wetland Determinations using 1987 and 1989 Methodologies A comparison of the wetland determination results using the Federal Manual for Identifying and Delineating Jurisdictional Wetlands (1989) and the 1987 Corps of Engineers Wetlands Delineation Manual was completed using data collected onsite. There were no differences observed in the location of the wetland edge when delineated using these two methods. WETLAND FUNCTION AND VALUE ASSESSMENT Wetlands are known to perform significant roles in the ecosystem, some of which are of immediate value to society. These roles var y greatly with the size, type, hydrology, vegetation, and location of wetland areas. Although the functions performed by these wetlands are complex, interrelated, and difficult to assess and quantify, methods have been developed for the U.S. Army Corps of Engineers (Adamus et al. 1987: Reppert et al. 1979). Valuable functions include: hydrologic support, shoreline protection, stormwater and floodwater storage, water quality, groundwater recharge, and natural biological functions (Table 1). FUNCTIONAL VALUATION The HYDROLOGIC SUPPORT FUNCTION is defined by the measure of hydrologic stability and environmental integrity which the wetland provides. This function is measured by the frequency of inundation and saturation by tidal actions, stream flow, runoff, and precipitation. Wetlands permanently inundated Tibbott Final Welland and Mitigation Report WetMilt.doc WETLAND VALUE CRITERIA FUNCTION LOW RATING MEDIUM RATING HIGH RATING HYDROLOGIC ;nlermlHenlly flooded seesonel;y flooded t in.erlidol or SUPPORT hydrologically isoleied or open water permanently flooded I SHORELINE wellond width < 100yds wellond width 100-200 yd> wellond width > 200yds PROTECTION ECTION from shoreline from shoreline from shoreline emergent or lacking sparse woody and dense woody vegetation veSelal;on dense emegenl vegetation undeveloped shoreline moderately developed highly developed shoreline shoreline STORMWATER $ FLOODWATER < 5 acres in size 5 l0 10 acres in size > 10 acres in size remote areas rural areas STORAGE urdan and developable < 10% woody cover 10 - 30% woody cover areas • > 30% woody cover WATER < 5 acres in size 5 - 10 acres in size > 10 acres in size QUALITY <50% vegetation density 50_80`/. vegetelion inle:miltenlly flooded density > 80% vegetation no proximity to downslrecm from density pollutants non-point pollutants downstream from retains < 25%. runoff reloins 25-50/. runoff re Point pollutants retains > 50% runoff GROUNDWATER RECHARGE < 5 acres i, size s - 10 acres ,., size > 10 acres ;n size isoloted secsonol!y flooded permanently inundated depressions lemporcrily sofurcled water depth to several feel impermeable subsf�c.'e NATURAL low plont diversity moderate plant diversify high plonl diversity BIOLOGICAL tcw wildlife diversify . two hobifel types three or more hcbifol features lock;ng several vegetation hobiJaf types FUNCTION one vegelolion cornmunify communities large wellond size smell wellond area moderate wellond size unique habitat features, isolated associated with intermiflenl Plants or animals present stream/ high salt marsh essocioled with permanent sireom/ tidol marsh \NETLAND ID. DATE or saturated, or intertidal wetlands are valued as high. Medium valued wetlands are seasonally flooded or are open water systems that remain saturated during most of the growing season. Wetlands that are intermittently flooded or hydrologically isolated are considered of low value. The SHORELINE PROTECTION FUNCTION is defined by the measure of shielding from wave action, erosion, or storm damage which a wetland provides. This function is measured by the location and width of the wetland along shoreline areas, types of vegetation present, and the extent of development along the shoreline. A high value is given to wetlands along a shoreline that have a width greater than 200 yards and dense woody vegetation. A medium value is given to a wetland with a width of 100 to 200 yards, sparse woody vegetation, and dense emergent vegetation. Wetlands less than 100 yards in width and emergent or lacking vegetation are considered of low value. The STORMWATER AND FLOODWATER STORAGE FUNCTION is defined by the ability of a wetland to store water and retard flow during periods of flood or storm discharge. Wetlands of larger size are generally considered to have greater ability to provide this function. In addition, wetlands nearer to urban or potentially developable areas are also considered to provide greater flood protections than wetlands which are in undeveloped areas. The WATER QUALITY FUNCTION is defined by the physical, biological, and chemical processes which wetlands provide to naturally purify water. This function removes organic and mineral particulates through natural filtration. In general, wetlands of greater size, more dense vegetation, and close to point sources of pollution are considered to be of higher value. ' Wetlands which are small (<5 acres), lacking dense vegetation, and not close to point or non-point sources of pollution are considered of low value. The GROUNDWATER RECHARGE FUNCTION is defined by the interaction of the underlying geology and soils, and the surface topography. This function provides for the movement of surface water into groundwater systems. Important to this function is wetland size, period of inundation, and depth of standing water within the v✓etland. High value is given to permanently inundated wetlands greater than 10 acres in size. Medium value is given to wetlands which are seasonally flooded and 5 to 10 acres in size. Wetlands less than 5 acres in size, isolated, and temporarily saturated are considered of low value. The NATURAL BIOLOGICAL FUNCTION is defined by the complexity of physical habitats and biological species within the wetland area. The value given to a wetland depends upon its ability to provide habitat for nesting (spawning), incubation, feeding, rearing, and cover• of aquatic and terrestrial animal and fish species. In addition, the ability of a wetland to provide support a Tbbott Final Wetland and Mitigation Report WetMitl.doc for varying food chains is an important element in value assessment. Wetlands of high species diversity, three or more habitat types, unique habitat features, large in size, and associated with a permanent stream or tidal marsh are considered of high value. Wetlands with moderate species diversity, two habitat types, moderate in size, and associated with an intermittent stream or high salt marsh are considered of medium value. A low value is given to wetlands of low species diversity, small size, and isolated. I These six functions are rated low, moderate, or high, based on the criteria outlined in Table 1. These criteria are guidelines compiled from Adamus (1987) and Reppert (1979) and professional judgment must be exercised in assessing these criteria. Overall values for a wetland are assigned, based on a synthesis of individual values. In addition to intrinsic functions, extrinsic functions are also recognized. These extrinsic functions provide social values that have indirect benefits to wetlands. Education and recreational opportunities are most often mentioned as extrinsic functions. Associated values are often in the eye of the beholder and are thus difficult to evaluate. As such, these functions are not rated, but are nonetheless important when considering creation, restoration, or enhancement projects. ONSITE WETLAND VALUATION The wetland area identified within the Site was evaluated following the functional value assessment process noted above. The offsite portions of the wetland were also given consideration in this process, though they were unavailable for the same level of assessment as they were located on private property. An evaluation form is provided in Appendix C. As identified in the functional value assessment Wetland A would be considered to have an overall value rating of Low - Medium and Wetland B would be j considered to have an overall value rating of Low. The rationale behind the overall rating of Low to Medium to Wetland A pertains to the small size of the wetland, the low to moderate diversity of plant species observed, the limited number of habitat types identified, and the temporarily flooded character of its hydrologic component. Wetland A did receive High marks as a result of 1) its location in an urban or developable area and 2) the amount of woody cover present. The rationale behind the overall rating to Wetland B of Low pertains to its hydrological isolation, the limited diversity of plant species observed, and its small size. 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Dean Tibbott Intermediate-level Onsite Method X Comprehensive Onsite Determination Method Transect# Plot# Vegetation Unit#/Name: Sample#within Veg. Unit: SOILS Series/Phase: Gravelly sandy loam Subgroup2 (EvB-AgC) Is the soil on the hydric soils list? YES NO X Undetermined Is the soil a Histosol? YES NO X Histic epipedon Present? YES NO Is the soil mottled? YES NO X Gleyed? YES NO X Matrix Color. 2.5Y 4/3-4/4 Mottle Colors: None Additional hydric soil indicators: Dry gravelly fill material Comments: Adjacent roadway ditchline. Appeared to be sidecast in origin HYDROLOGY Is the ground surface inundated? YES NO X Surface water depth: Is the soil saturated? YES X NO X Depth to free-standing water in pit/soil probe hole? > Mark other field indicators of surface inundation or soil saturation below: Oxidized root zones Water-stained leaves Watermarks Surface scoured areas Drift lines Wetland drainage patterns Water-bome sedimental deposits Morphological plant adaptations Additional hydrologic indicators: None Comments: Percent of dominant species that are OBL,FACW and/or FAC? 0.0 Is the hydrophytic vegetation criterion met? YES NO X Is the hydric soil criterion met? YES NO X Is the wetland hydrology criterion met? YES NO X Is the vegetation unit or plot wetland? YES NO X Reason for jurisdictional decision: . Lacked mandatory technical criteria I SAMPLE PLOT SP-1 DATA FORM INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD VEGETATION UNIT SAMPLING PROCEDURE f Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Vegetation Unit#/Name: Herb SpeciesN ~Y Indicator Percent Cover yMid oint�of Rank2 Status Areal Cover Class Cover Class 1. 2. T` 3. 4. 5. 6. 7. 8. 9. \ 10. \ 11. ` 12. Shrub Species \ 13. Corylus comuta FacLI 25 14.- Rubus lacianatus FacU+ 10 \ 15. Gaultheria shallop FacU 100 16. \ 17. \. 18. \ 19. \ 20. \ 21. \ 22. Saptina Species 23. 24. 25. \ 26. \ 27. \ 28. \ 29. \ 30. \ Tree Species \ 31. 32. \ 33 \ 34. \Sum of Midpoints Dominance Threshold Number Equals 50%X sum of Midpoints DATA FORM SAMPLE PLOT SP-2 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD OR COMPREHENSIVE ONSITE DETERMINATION METHOD (Soils and Hydrology) ■ Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Intermediate-level Onsite Method X Comprehensive Onsite Determination Method Transect# Plot# Vegetation Unit#/Name: Sample#within Veg. Unit: SOILS Series/Phase: Gravelly sandy loam Subgroup2 (EvB-AgC) Is the soil on the hydric soils list? YES NO X Undetermined Is the soil a Histosol? YES _ NO X Histic epipedon Present? YES NO Is the soil mottled? YES NO X Gleyed? YES NO X Matrix Color. 2.5Y 4/3-4/4 Mottle Colors: none Additional hydric soil indicators: Comments: _Adjacent ditchline along NE 4th Street HYDROLOGY Is the ground surface inundated? YES NO X Surface water depth: Is the soil saturated? YES X NO '—'-- Depth to free-standing water in pit/soil probe hole? 4" Mark other field indicators of surface inundation or soil saturation below: Oxidized root zones Water-stained leaves Water marks Surface scoured areas Drift lines Wetland drainage patterns Water-bome sedimental deposits Morphological plant adaptations Additional hydrologic indicators: None Percent of dominant species that are OBL,FACW and/or FAC? 5 Is the hydrophytic vegetation criterion met? YES NO X Is the hydric soil criterion met? YES NO X Is the wetland hydrology criterion met? YES X NO Is the vegetation unit or plot wetland? YES NO X Reason for jurisdictional decision: Failed to satisfy mandatory criteria. SAMPLE PLOT SP-2 DATA FORM SAMPLE PLOT SP-2 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD VEGETATION UNIT SAMPLING PROCEDURE Field Investigators) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Vegetation Unit#/Name: Herb Species Indicator Percent Cover Midpoints of Rank? Status Areal Cover Class Cover Class 12. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. Shrub Species 13. Spiraea douglasii FacW 20 3 20.5 1' 14. Rubus lacianatus FacU+ 10 2 10.5 2' 15. 16. 17. 18. 19. " 0.2 22. Sapling Species 23. Populus trichocarpa Fac T 24. 25. 26. 27. 28. 29. 30. Tree Species 31. 32. 33 34. Sum of Midpoints 31 Dominance Threshold Number Equals 50% X sum of Midpoints 15.5 DATA FORM SAMPLE PLOT SP-3 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD OR COMPREHENSIVE ONSITE DETERMINATION METHOD (Solis and Hydrology) Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King ApplicanUOwner. Dean Tibbott Intermediate-level Onsite Method X Comprehensive Onsite Determination Transect# Plot# Vegetation Unit#/Name: Sample#within Veg. Unit: SOILS Series/Phase: Gravelly sandy loam Subgroup2 _ (EVB-A C) Is the soil on the hydric soils list? YES _ NO X Undetermined Is the soil a Histosol? YES NO X Histic epipedon Present? YES NO Is the soil mottled? YES NO X Gleyed? YES NO X Matrix Color. 7.5YR 3/3 Mottle Colors: None Additional hydric soil indicators: Saturated sandy loam Comments: HYDROLOGY Is the ground surface inundated? YES NO X Surface water depth: Is the soil saturated? YES X NO Depth to free-standing water in pit/soil probe hole? 4" Mark other field indicators of surface inundation or soil saturation below- . Oxidized root zones Water-stained leaves Watermarks Surface scoured areas Drift lines Wetland drainage patterns Water-bome sedimental deposits Morphological plant adaptations Additional hydrologic indicators: Comments: Percent of dominant species that are OBL,FACW and/or FAC? 50 Is the hydrophytic vegetation criterion met? YES NO X Is the hydric soil criterion met? YES NO X Is the wetland hydrology criterion met? YES X NO Is the vegetation unit or plot wetland? YES NO X Reason for jurisdictional decision: Lacked mandatory technical criteria DATA FORM SAMPLE PLOT SP-3 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD VEGETATION UNIT SAMPLING PROCEDURE Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Vegetation Unit#/Name: Herb Species Indicator �~ Percent Cover Mid ointl of Rank? Status Areal Cover Class,\ Cover Class 1. 2. \ 3. 4. \ 5. \ 6. 7. 8. \ 90 \� 11. \ Shrub \ Shrub Species 13. Gaultheria shallon FacU 100 14. 15. 16. 19. 20. \ 21. \ 22. \ Sapling Species \ 23. 24. \ 25. � 26. \ 27. Tree Species 28. Pseudotsuga FacU 30 \ menziesii 29. Tsuga heterophylla FacU- 30 30 Sum of Midpoints Dominance Threshold Number Equals 50%X sum of Midpoints 1. Cover classes(midpoints):T<1%(none);1 =1-5%(3.0);2=6-15%(10.5);3=16-25%(20.5);4=26-50%(38.0);5=51-75%(63.0); 6=76-95%(85.5);7=96-100%(98.0). 2. To determine the dominants,first rank the species by thew midpoints. Then cumulatively sum the midpoints of the ranked species until 50%of the total for all species midpoints is immediately exceeded. All species contributing to that cumulative total(the dominance threshold number)plus any additional species having 20%of the total midpoint value should be considered dominants and marked with an asterisk i DATA FORM SAMPLE PLOT SP-4 . INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD OR COMPREHENSIVE ONSITE DETERMINATION METHOD (Soils and Hydrology) Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Intermediate-level Onsite Method X Comprehensive Onsite Determination Method Transect# Plot# Vegetation Unit#/Name: Sample #within Veg. Unit: SOILS Series/Phase: Gravelly sandy loam Subgroup2 (EvB-An(') Is the soil on the hydric soils list? YES NO X Undetermined Is the soil a Histosol? YES NO X Histic epipedon Present? YES Is the soil mottled? YES NO NO X Gleyed7 YES NO X Matrix Color. 10YR 3/1-2/1 Mottle Colors: None Additional hydric soil indicators: Saturated sift loam Comments: rJ ��I rl t U HYDROLOGY Is the ground surface inundated? YES X NO Surface water depth: 2" Is the soil saturated? YES X NO Depth to free-standing water in piVsoil probe hole? Mario other field indicators of surface inundation or soil saturation below. Oxidized root zones Water-stained leaves Water marks Surface scoured areas Drift lines Wetland drainage patterns Water-borne sedimental deposits Morphological plant adaptations Additional hydrologic indicators: Comments: Percent of dominant species that are OBL,FACW and/or FAC? 100 Is the hydrophytic vegetation criterion met? YES X NO Is the hydric soil criterion met? YES X NO Is the wetland hydrology criterion met? YES X NO is the vegetation unit or plot wetland? YES X NO Reason for jurisdictional decision: Satisfies mandato r technical criteria DATA FORM SAMPLE PLOT SP-4 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD VEGETATION UNIT SAMPLING PROCEDURE Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 ProjecUSite: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Vegetation Unit#/Name: Herb Species Indicator Percent Cover Midpoints of Rank? Status Areal Cover Class Cover Class 2. �\ 3. 4. 5. 6. 7. \\ 8. \ 90 \ 11. 12. Shrub Species \ 13. Spiraea douglasii FacW 100 14. 15. 16. 19. �\ 20.' \ 21. 22. Sapling Species 23. 24. 25. •� 26. -- 27. Tree Species 28. 29. 30 Sum of Midpoints Dominance Threshold Number Equals 50% X sum of Midpoints 1. Cover classes(midpoints):T<1%(none);1 =1-5%(3.0);2=6-15%(10.5);3=16.25%(20.5);4=26-50%(38.0);5=51-75%(63.0); 6=76-95%(85.5);7=96-100%(98.0). 2. To determine the dominants,first rank the species by their midpoints. Then cumulatively sum the midpoints of the ranked species until 50%of the total for all species midpoints is immediately exceeded. All species contributing to that cumulative total(the dominance threshold number)plus any additional species having 20%of the total midpoint value should be considered dominants and marked with an asterisk. I DATA FORM SAMPLE PLOT SP-5 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD OR COMPREHENSIVE ONSITE DETERMINATION METHOD (Soils and Hydrology) Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 ProjecUSite: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Intermediate-level Onsite Method X Comprehensive Onsite Determination Method Transed# Plot# Vegetation Unit#/Name: Sample#within Veg. Unit: SOILS Series/Phase: Gravelly sandy loam Subgroup, (EvB-A C) Is the soil on the hydric soils list? YES NO X _ Undetermined Is the soil a Histosol? YES NO X Histic epipedon Present? YES NO Is the soil mottled? YES NO X Gleyed? YES NO X Matrix Color. 2.5Y 4/3-4/4 Mottle Colors: None Additional hydric soil indicators: Saturated gravelly sandy loam Comments: HYDROLOGY Is the ground surface inundated? YES NO X Surface water depth: Is the soil saturated? YES X NO Depth to free-standing water in pit/soil probe hole? >1 g" Mark other field indicators of surface inundation or soil saturation below. Oxidized root zones Water-stained leaves Water marks Surface scoured areas Drift lines Wetland drainage patterns Water-bome sedimental deposits Morphological plant adaptations Additional hydrologic indicators: Comments: Percent of dominant species that are OBL,FACW and/or FAC? >50 Is the hydrophytic vegetation criterion met? YES X NO Is the hydric soil criterion met? YES NO X Is the wetland hydrology criterion met? YES NO X Is the vegetation unit or plot wetland? YES NO X Reason for jurisdictional decision: Failed to satisfy mandatory technical criteria DATA FORM SAMPLE PLOT SP-6 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD VEGETATION UNIT SAMPLING PROCEDURE Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott — ---- Vegetation Unit#/Name: -_ Herb Species Indicator Percent Cover Midpoint!of Rank? Status Areal Cover Class Cover Class 2. ----- 4. 5. 6. 7. - 8. 10. 11. 12. Shrub Species 13. 14. Gualtheria shallon FacU 100 \ 15. 16. 19. 20. —� 21. —� 22. —\ Sapling Species \ 23. 24. 25. 27. Tree Species \ 28. Pseudotsuga Fac 100 menziesii 29. 30 Sum of Midpoints 1 Dominance Threshold Number Equals 50%X sum of Midpoints 1. Cover classes(midpoints):T<1%(none);1 =1-5%(3.0);2=6-15%(10.5);3=16-25%(20.5);4=26-50%(38.0);5=51-75%(63.0); 6=76.95%(85.5);7=96-100%(98.0). 2- To determine the dominants,rust rank the species by their midpoints. Then cumulatively sum the midpoints of the ranked species until 50%of the total for all species midpoints is immediately exceeded. All species contributinfl to that cumulative total(the dominance threshold number)plus any additional species having 20%of the total midpoint value should be considered dominants and marked with an asterisk. SAMPLE PLOT SP-7 DATA FORM INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD OR COMPREHENSIVE ONSITE DETERMINATION METHOD (Soils and Hydrology) Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 1 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Intermediate-level Onsite Method X Comprehensive Onsite Determination Method Transect# Plot# Vegetation Unit#/Name: Sample#within Veg. Unit: SOILS J Series/Phase: Gravelly sandy loam Subgroup2 (EvB-AgC) Is the soil on the hydric soils list? YES NO X Undetermined Is the soil a Histosol? YES NO X Histic epipedon Present? YES NO Is the soil mottled? YES NO X Gleyed? YES NO X Matrix Color. 10YR 2/2 Mottle Colors: None Additional hydric soil indicators: Saturated gravelly loam Comments: Very gravelly material • HYDROLOGY Is the ground surface inundated? YES NO X Surface water depth: Is the soil saturated? YES X NO Depth to free-standing water in pit/soil probe hole? 6" Mark other field indicators of surface inundation or soil saturation below: Oxidized root zones Water-stained leaves Water marks Surface scoured areas Drift lines Wetland drainage patterns Water-bome sedimental deposits Morphological plant adaptations Additional hydrologic indicators: Comments: Located in corridor between two areas exhibiting hydric soils May be old logging road Percent of dominant species that are OBL,FACW and/or FAC? 100.0 Is the hydrophytic vegetation criterion met? YES X NO Is the hydric soil criterion met? YES NO X Is the wetland hydrology criterion met? YES X NO Is the vegetation unit or plot wetland? YES NO X Reason for jurisdictional decision: Failed to satisfy mandatory technical criteria-soils appeared infrequently saturated and/or well drained DATA FORM SAMPLE PLOT SP-7 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD VEGETATION UNIT SAMPLING PROCEDURE Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King ApplicanUOwner. Dean Tibbott Vegetation Unit#/Name: Herb Species Indicator Percent Cover Midpoint!of Rank? Status Areal Cover Class Cover Class 1. 2. 3. 4. 5. 6. 7. 9. 8. \ 10. 11. 12. \ Shrub Species \ 13. 14. Rubus spectabilis Fac+ 25 15. 16. 19. - - 20. -- 21. -- \ 22. Saplina Species 23. Fraxinus latifolia FacW 35 \\ 24. 25. 26. 27. Tree Species 28. 29. 30 Sum of Midpoints Dominance Threshold Number Equals 50%X sum of Midpoints 1. Cover classes(midpoints):T<1%(none);1 =1-5%(3.0);2=6-15%(10.5);3=16-25%(20.5);4=26-50%(38.0);5=51-75%(63.0); 6=76-95%(85.5);7=96-100%(98.0). 2. To determine the dominants,first rank the species by their midpoints. Then cumulatively sum the midpoints of the ranked species until 50%of the total for an species midpoints is Immediately exceeded. An species contributing to that cumulative total(the dominance threshold number)plus any additional species having 20%of the total midpoint value should be considered dominants and marked with an asterisk. SAMPLE PLOT SP-8 DATA FORM INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD OR COMPREHENSIVE ONSITE DETERMINATION METHOD (Soils and Hydrology) Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Intermediate-level Onsite Method X Comprehensive Onsite Determination Method Transect# Plot# Vegetation Unit#/Name: Sample#within Veg. Unit: SOILS Series/Phase: Gravelly sandy loam Subgroup2 (EvB-AgC) Is the soil on the hydric soils list? YES . NO X Undetermined Is the soil a Histosol? YES NO X Histic epipedon Present? YES NO Is the soil mottled? YES NO X Gleyed? YES NO X Matrix Color. 10YR 3/2 Mottle Colors: None Additional hydric soil indicators: Saturated gravelly loam Comments Very gravelly material HYDROLOGY Is the ground surface inundated? YES NO X Surface water depth: Is the soil saturated? YES X NO Depth to free-standing water in pit/soil probe hole? 6" Mark other field indicators of surface inundation.or soil saturation below: Oxidized root zones Water-stained leaves Water marks Surface scoured areas Drift lines Wetland drainage patterns Water-borne sedimental deposits Morphological plant adaptations Additional hydrologic indicators: Comments: Located in corridor between two areas exhibiting hydric soils May be old logging road Percent of dominant species that are OBL,FACW and/or FAC? 100.0 Is the hydrophytic vegetation criterion met? YES X NO Is the hydric soil criterion met? YES NO X Is the wetland hydrology criterion met? YES X NO Is the vegetation unit or plot wetland? YES NO X Reason for jurisdictional decision: Failed to satisfy mandatory technical criteria-soils appeared infrequently saturated and/or well drained DATA FORM SAMPLE PLOT SP-8 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD VEGETATION UNIT SAMPLING PROCEDURE Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave..and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Vegetation Unit#/Name: Herb Species Indicator Percent Cover Midpoints of Rank2 Status Areal Cover Class Cover Class 1. 2. 3. 4. 5. 6. - 7. — 8. 9. 10. 11. 12. Shrub Species 13. 14. Rubus spectabilis Fac+ 25 3 _ z9.s I 15. Oemlaria FacU- 10 Z cerasiformis - S 19. , 20. 21. 22. Sapling Species 23. 24. 25. 26. 27. Tree Species 28. Pseudotsuga FacU 5 menziesii 29. Populus trichocarpa Fac 50 30 Sum of Midpoints 7Z- Dominance Threshold Number Equals 50% X sum of Midpoints �is 1. Cover classes(midpoints):T<1%(none);1 =1-5%(3.0);2-6-15%(10.5);3=16 25%(20.5);4=26-50%(38.0);5=51-75%(63.0); 6=76-95%(85.5);7=96-100%(98.0). 2. To determine the dominants,first rank the species by their midpoints. Then cumulatively sum the midpoints of the ranked species until 50%of the total for all species midpoints Is Immediately exceeded. AN species contributing to that cumulative total(the dominance DATA FORM SAMPLE PLOT SP-9 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD OR COMPREHENSIVE ONSITE DETERMINATION METHOD (Soils and Hydrology) Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Intermediate-level Onsite Method X Comprehensive Onsite Determination Method Transect# Plot# _ Vegetation Unit#/Name: Sample#within Veg. Unit: SOILS Series/Phase: Gravelly sandy loam Subgroup2 (EvB-AQC) Is the soil on the hydric soils list? YES NO X Undetermined Is the soil a Histosol? YES NO X Histic epipedon Present? YES NO Is the soil mottled? YES NO X Gleyed? YES NO X Matrix Color. 10YR 3/3 Mottle Colors: None Additional hydric soil indicators: Saturated gravelly loam Comments: HYDROLOGY Is the ground surface inundated? YES NO X Surface water depth: Is the soil saturated? YES X NO Depth to free-standing water in pit/soil probe hole? 6" Mark other field indicators of surface inundation or soil saturation below- Oxidized root zones Water-stained leaves Water marks Surface scoured areas Drift lines Wetland drainage patterns Wafer-borne sedimental deposits Morphological plant adaptations Additional hydrologic indicators: Comments: Percent of dominant species that are OBL,FACW and/or FAC? >50 Is the hydrophytic vegetation criterion met? YES X NO Is the hydric soil criterion met? YES NO X Is the wetland hydrology criterion met? YES X NO Is the vegetation unit or plot wetland? YES NO X Reason for jurisdictional decision: Failed to satisfy mandatory technical criteria-soils appeared well drained SAMPLE PLOT SP-9 DATA FORM INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD VEGETATION UNIT SAMPLING PROCEDURE Field Investigator(s) WDI -Dave F isvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Vegetation Unit#/Name: Herb Species Indicator Percent Cover Midpoint!of Rank? Status Areal Cover Class Cover Class 1. 2. 3. 4. 5. 6. 7. ^\ 8. - \ 9. \ 10. 11. 12. _ Shrub Species 13. 14. Rubus spectabilis Fac+ 15 \ 15. Oemlaria Fac T cerasiformis \ 16. Rubus proceru FacU 10 \ 20. 21. 22. Sapling Species \ 23. Fraxinus latifolia FacW 15 24. \ 25. \ 26. 27. Tree Species 28. Alnus rubra Fac 70 \ 29. 30 Sum of Midpoints Dominance Threshold Number Equals 50%X sum of Midpoints 1. Cover classes(midpoints):T<1%(none);1 =1-5%(3.0);2=6-15%(10.5);3=16-25%(20.5);4=26-50%(38.0);5=51-75%(63.0); 6=76-95%(85.5);7=96-100%(98.0). Z To determine the dominants,first rank the species by their midpoints. Then cumulatively sum the midpoints of the ranked species until 50%of the total for all species midpoints Is immediately exceeded. All species contributing to that cumulative total(the dominance threshold number)plus any addit"t species having 20%of the total midpoint value should be considered dominants and marked with an asterisk. DATA FORM SAMPLE PLOT SP-10 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD OR COMPREHENSIVE ONSITE DETERMINATION METHOD (Soils and Hydrology) Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Intermediate-level Onsite Method X Comprehensive Onsite Determination Method Transect# Plot# Vegetation Unit#/Name: Sample#within Veg. Unit: SOILS Series/Phase: Gravelly sandy loam Subgroup2 (EvB-A C) Is the soil on the hydric soils list? YES NO X Undetermined Is the soil a Histosol? YES NO X Histic epipe ent? YES NO Is the soil mottled? YES NO X Gleyed? YES NO X Matrix Color. 10YR 3/1 Mottle Colors: None Additional hydric soil indicators: Saturated silty loam Comments: HYDROLOGY Is the ground surface Inundated? YES X NO Surface water depth: Is the soil saturated? YES X NO Depth to free-standing water in pit/soil probe hole? Surface i i Mark other field indicators of surface inundation or soil saturation below: Oxidized root zones Water-stained leaves Watermarks Surface scoured areas Drift lines Wetiand drainage patterns Water-bome sedimental deposits Morphological plant adaptations Additional hydrologic indicators: Comments: Percent of dominant species that are OBL,FACW and/or FAC? 100 Is the hydrophytic vegetation criterion met? YES X NO Is the hydric soil criterion met? YES X NO Is the wetland hydrology criterion met? YES X NO Is the vegetation unit or plot wetland? YES X NO Reason for jurisdictional decision: Satisfies mandatory technical criteria DATA FORM SAMPLE PLOT SP-10 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD VEGETATION UNIT SAMPLING PROCEDURE Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Vegetation Unit#/Name: _ Herb Species Indicator Percent Cover Mid ointi of Rank? Status Areal Cover Class Cover Class 1. 3 ` 4 \� 5. \ 6. \ 7. \ 8. 9. 10. 11. \ 12. Shrub Species 13. \ 14. Rubus spectabilis Fac+ T \ 15. Spiraea douglasii FacW T 16. 19. 20. 21. 22. \ Sapling Species \ 23. Fraxinus latifolia FacW 15 24. \ 2 . \ 26. �- 27. Tree Species 28. Populus trichocarpa Fac 100 29. 30 Sum of Midpoints Dominance Threshold Number Equals 50%X sum of Midpoints 1. Cover classes(midpoints):T<t%(none); 1 =1-5%(3.0);2=6-15%(10.5);3=16-25%(20.5);4=26-50%(38.0);5=51-75%(63.0); 6=7&95%(85.5);7=96-100%(98.0). 2. To determine the dominants,first rank the species by their midpoints. Then cumulatively sum the midpoints of the ranked species until 50%of the total for an species midpoints is immediately exceeded. All species contributing to that cumulative total(the dominance ttueshoki number)plus any additional species having 20%of the total midpoint value should be considered dominants and marked with an asterisk. 1 J JDATA FORM SAMPLE PLOT SP-11 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD OR COMPREHENSIVE ONSITE DETERMINATION METHOD (Soils and Hydrology) Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/She; Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Intermediate-level Onsite Method -X Comprehensive Onsite Determination Method Transect# Plot# _ Vegetation Unit#/Name: Sample#within Veg. Unit: SOILS Series/Phase: Gravelly sandy loam Subgroupz (EvB-AgC) Is the soil on the hydric soils list? YES NO X Undetermined Is the soil a Histosol? YES NO X Histic epipedon Present? YES NO Is the soil mottled? YES NO X Gleyed? YES NO X Matrix Color. 10YR 3/1 Mottle Colors: None Additional hydric soil indicators: Saturated silty loam Comments: HYDROLOGY Is the ground surface inundated? YES X NO Surface water depth: Is the soil saturated? YES X NO Depth to free-standing water in pit/soil probe hole? 2 Mark other field indicators of surface inundation or soil saturation below. , Oxidized root zones Water-stained leaves Water marks Surface scoured areas Drift lines Wetland drainage patterns -_ Water-bome sedimental deposits Morphological plant adaptations Additional hydrologic indicators: Comments: Percent of dominant species that are OBL,FACW and/or FAC? 100 Is the hydrophytic vegetation criterion met? YES X NO Is the hydric soil criterion met? YES X NO Is the wetland hydrology criterion met? YES X NO Is the vegetation unit or plot wetland? YES X NO Reason for jurisdictional decision: Offsite Sample Point-satisfied mandatory criteria DATA FORM SAMPLE PLOT SP-11 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD VEGETATION UNIT SAMPLING PROCEDURE Field Investigator(s) WDI -Dave Risvold Date: 4117/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Vegetation Unit#/Name: Herb Species rIndicator Percent Cover _ Mid ointl of Rank? Status Areal Cover Class Cover Class 2. \\ 3. 4. 5. 6. 7. \ 10. 12. Shrub Species \ 13. 14. Rubus spectabilis Fac+ 20 15. Spiraea douglasii FacW 10 \ 16. 19. 20. 21. 22. \ Sapling Species 23. Fraxinus latifolia FacW 25 \ 24. 25. 26. 27. Tree Species 28. Populus trichocarpa Fac 100 29. 30 '--- Sum of Midpoints Dominance Threshold Number Equals 50%X sum of Midpoints 1. Cover classes(midpoints):T<1%(none);1 =1-5% 3.0;2=6-15% 10. •3=16-25% 20. .4=26-50% 38.0;5=51-75% 63.0; 6=76-95%(85.5);7=96-100%(98.0). 2. To determine the dominants,first rank the species by their midpoints. Then cumulatively sum the midpoints of the ranked species until 50%of the total for all species midpoints is immediately exceeded. All species contributing to that cumulative total(the dominance threshold number)plus any additional species having 20%of the total midpoint value should be considered dominants and marked with an asterisk. DATA FORM SAMPLE PLOT SP-12 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD OR COMPREHENSIVE ONSITE DETERMINATION METHOD (Soils and Hydrology) Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA _ County: King ApplicanUOwner. Dean Tibbott Intermediate-level Onsite Method X Comprehensive Onsite Determination Method Transect# Plot# Vegetation Unit#/Name: Sample#within Veg. Unit: SOILS Series/Phase: Gravelly sandy loam Subgroup2 (EvB-AgC) is the soil on the hydric soils list? YES " NO X Undetermined Is the soil a Histosol? YES NO X Histic epipedon Present? YES NO Is the soil mottled? YES NO X Gleyed? YES NO X Matrix Color. 10YR 3/1 Mottle Colors: None Additional hydric soil indicators: Saturated silty loam Comments HYDROLOGY Is the ground surface inundated? YES NO X Surface water depth: Is the soil saturated? YES X NO Depth to free-standing water in pit/soil probe hole? surface Mark other field indicators of surface inundation or soil saturation below: Oxidized root zones Water-stained leaves Water marks Surface scoured areas Drift lines Wetland drainage patterns Water-bome sedimental deposits Morphological plant adaptations Additional hydrologic indicators: Sulfidic smell Comments: Percent of dominant species that are OBL,FACW and/or FAC? <50 Is the hydrophytic vegetation criterion met? YES X- NO Is the hydric soil criterion met? YES X NO Is the wetland hydrology criterion met? YES X NO Is the vegetation unit or plot wetland? YES X NO Reason for jurisdictional decision: Satisfied mandatory criteria -vegetation presumed to be acting hydrophytically due to presence of hydric soils and hydrology DATA FORM SAMPLE PLOT SP-12 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD VEGETATION UNIT SAMPLING PROCEDURE Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 ProjecUSite: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Vegetation Unit#/Name: Herb Species Indicator Percent _ Cover N Midpoint1 of Ran Status Areal Cover Class Cover Class 1. Ranunculus repens FacW- 10 2 10.5 1" 2. Polystichum munitum FacU 15 2 10.5 1` 3. Athyrium felix-femina Fac+ 5 1 3.0 2 4. 5. 6. 7. 8. - 90 11. 12. Shrub Species 13. 14. 15. 16. 19. 20. 21. 22. Sapling Species 23. Rhamnus pursiana Fac- 25 3 20.5 1' 24. 25. 26. 27. Tree Species 28. - Pseudotsuga FacU 25 3 20.5 1' menziesii 29. 30 Sum of Midpoints 65 Dominance Threshold Number Equals 50% X sum of Midpoints 32.5 1. Cover classes(midpoints):T<1%(none);1 =1-5%(3.0);2=6-15%(10.5);3 a 16 25%(20.5);4=26 50%(38.0);5=51-75%(63.0); 6=76-95%(85.5);7=96-100%(98.0). 2. To determine the dominants,first rank the species by their midpoints. Then cumulatively sum the midpoints of the ranked species until 50%of the total for an species midpoints Is Immediately exceeded. An species contributing to that cumulative total(the dominance threshold number)plus any additional species having 20%of the total midpoint value should be considered dominants and marked with an asterisk 1 DATA FORM SAMPLE PLOT SP-13 a INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD OR COMPREHENSIVE ONSITE DETERMINATION METHOD (Soils and Hydrology) Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street---Re�nton State: WA County: King_ Applicant/Owner. Dean Tibbott Intermediate-level Onsite Method X Comprehensive Onsite Determination Method Transect# Plot# Vegetation Unit#/Name: Sample #within Veg. Unit: SOILS Series/Phase: Gravelly sandy loam Subgroup2 (EvB-Agq Is the soil on the hydric soils list? YES NO X Is the soil a Histosol? YES Undetermined NO X Histic epipedon Present? YES NO Is the soil mottled? YES NO X Gleyed? YES Matrix Color. 10YR 3/2 M NO X Mottle Colors: None -' Additional hydric soil indicators: Saturated sandy gravelly loam Comments: Is the ground surface inundated? YES HYDROLOGY Is the soil saturated? NO X YES X NO Surface water depth: Depth to free-standing water in pit/soil probe hole? 3" Mark other field indicators of surface inundation or soil saturation below. Oxidized root zones Water-stained leaves Water marks Surface scoured areas Drift lines Wetland drainage patterns Water-bome sedimental deposits Morphological plant adaptations Additional hydrologic indicators: Comments: Percent of dominant species that are OBL,FACW and/or FACT Is the hydrophytic vegetation criterion met? YES <50 Is the hydric soil criterion met? NO X YES NO X Is the wetland hydrology criterion met? YES X Is the vegetation unit or lot wetland? NO p YES NO X Reason for jurisdictional decision: Failed to satisfy mandatory criteria SAMPLE PLOT SP-13 DATA FORM INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD VEGETATION UNIT SAMPLING PROCEDURE Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 ProjecUSite: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Vegetation Unit#/Name: Herb Species Indicator Percent �~ Cover Mid ointl.of Ran ? Status Areal Cover Class Cover Class 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. Shrub Species 13. Gaultheria shallon FacU 70 14. Acer circinatum Fac- 100 15. Corylus comuta FacU 10 16. 19. 20. 21. 22. Sapling Species 23. 24. 25. 26. 27. Tree Species 28. 29. 30 Sum of Midpoints 65 Dominance Threshold Number Equals 50% X sum of Midpoints 32.5 1. Cover classes(midpoints):T<1%(none);1 =1-5%(3.0);2=6-15%(10.5);3=16-25%(20.5);4=26-50%(38.0);5=51-75%(63.0); 6=76-95%(85.5)•7=96-100%(98.0). 2. To determine the dominants,first rank the species by their midpoints. Then cumulatively sum the midpoints of the ranked species until 50%of the total for all species midpoints is immediately exceeded. All species contributing to that cumulative total(the dominance threshold number)plus any additional species having 20%of the total midpoint value should be considered dominants and marked with an asterisk i DATA FORM SAMPLE PLOT SP-14 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD OR COMPREHENSIVE ONSITE DETERMINATION METHOD (Soils and Hydrology) Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott — ----- intermediate-level Onsite Method X J Comprehensive Onsite Determination Method Transect# Plot# Vegetation UniWName: Sample #within Veg. Unit: SOILS Series/Phase: Gravelly sandy loam Subgroup2 (EvB-AgC) ' Is the soil on the hydric soils list? YES NO X Undetermined Is the soil a Histosol? YES NO X Histic epipedon Present? YES NO Is the soil mottled? YES NO X Gleyed? YES NO X ' Matrix Color. 10YR 3/3 Mottle Colors: None Additional hydric soil indicators: Saturated sandy gravelly loam ' Comments: HYDROLOGY Is the ground surface inundated? YES NO X Surface water depth: Is the soil saturated? YES X NO Depth to free-standing water In pit/soil probe hole? 12" Mark other field indicators of surface inundation or soil saturation below: Oxidized root zones Water-stained leaves Water marks Surface scoured areas Drift lines Wetland drainage patterns Water-bome sedimental deposits Morphological plant adaptations Additional hydrologic indicators: Comments: Percent of dominant species that are OBL,FACW and/or FAC? 50 Is the hydrophytic vegetation criterion met? YES NO X Is the hydric soil criterion met? YES NO X Is the wetland hydrology criterion met? YES X NO Is the vegetation unit or plot wetland? YES NO X Reason for jurisdictional decision: Failed to satisfy mandatory criteria SAMPLE PLOT SP-14 '!�? — /I q DATA FORM INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD VEGETATION UNIT SAMPLING PROCEDURE Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Vegetation Unit#/Name: Herb Species Indicator Percent Cover Mid oint1 of Rank Status Areal Cover Class Cover Class 1. Trillium ovatum UPL T 0.0 2. 3. 5. 6. 7. 8. 9. 10. 11. 12. Shrub Species 13. Gaultheria shallon FacU 50 4 38.0 2• 14. Rubus spectabilis Fac+ 100 7 98.0 1' 15. 16. 19. 2 . - 21. 22. Sapling Species 23. 24. 25. 26. 27. Tree Species 28. 29. 30 Sum of Midpoints 136 Dominance Threshold Number Equals 50%X sum of Midpoints 68 1. Cover classes(midpoints):T<1%(none);f=1-5%(3.0);2-6-15%(10.5);3-16-25%(20.5);4-26-50%(38.0);5=51-75%(63.0); 6=76-95%(85.5)•7=96-100%(98.0). 2- To determine the dominants,first rank the species by their midpoints. Then cumulatively sum the midpoints of the ranked species until 50%of the total for all species midpoints is immediately exceeded. All species contributing to that cumulative total(the dominance threshold number)plus any additional species having 20%of the total midpoint value should be considered dominants and marked with an asterisk i r DATA FORM SAMPLE PLOT SP-15 INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD OR COMPREHENSIVE ONSITE DETERMINATION METHOD (Soils and Hydrology) Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Intermediate-level Onsite Method X Comprehensive Onsite Determination Method Transect# Plot# _ Vegetation Unit#/Name: Sample#within Veg. Unit: SOILS Series/Phase: Gravelly sandy loam Subgroup2 (EvB-AgC) Is the soil on the hydric soils list? YES NO X Undetermined Is the soil a Histosol? YES NO X Histic epipePre-sent? YES NO Is the soil mottled? YES NO X Gleyed? YES NO X Matrix Color. 2.5Y 3/3 Mottle Colors: None Additional hydric soil indicators: Saturated sandy gravelly loam Comments: Located adjacent to road corridor- offsite to north HYDROLOGY Is the ground surface inundated? YES X . NO Surface water depth: Is the soil saturated? YES X NO Depth to free-standing water in pit/soil probe hole? ' surface Mark other field indicators of surface inundation or soil saturation below: Oxidized root zones Water-stained leaves Water marks Surface scoured areas Drift lines Wetland drainage patterns Water-bome sedimental deposits Morphological plant adaptations Additional hydrologic indicators: Percent of dominant species that are OBL,FACW and/or FAC? 0.0• Is the hydrophytic vegetation criterion met? YES NO X Is the hydric soil criterion met? YES NO X Is the wetland hydrology criterion met? YES X NO Is the vegetation unit or plot wetland? YES NO X Reason for jurisdictional decision: Failed to satisfy mandatory criteria-vegetation had been cleared as a result of roadway construction. Soils appeared well drained. SAMPLE PLOT SP-15 DATA FORM INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD VEGETATION UNIT SAMPLING PROCEDURE Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Vegetation Unit#/Name: Herb Species _ Indicator Percent Cover Midpoint!of Rank? y Status Areal Cover Class Cover Class 12. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. Shrub Species 13. 14. ' 15. 1 . 19.- 20. , 21. 22. Saplin4 Species 23. Sorbus sitchensis UPI 10 24. 25. 26. 27. Tree Species 28. 29. 30 Sum of Midpoints Dominance Threshold Number Equals 50% X sum of Midpoints 1. Covet classes(midpoints):T<1%(none);1 =1-5%(3.0);2=6-15%(10.5);3=16.25%(20.5);4=26-50%(38.0);5=51-75%(63.0); 6=76-95%(85.5);7=96-100%(98.0). 2. To determine the dominants,first rank the species by their midpoints. Then cumulatively sum the midpoints of the ranked species until 50%of the total for all species midpoints is immediately exceeded. Ali species contributing to that cumulative total(the dominance threshold number)plus any additional species having 20%of the total midpoint value should be considered dominants and marked with an asterisk. SAMPLE PLOT SP-16 DATA FORM INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD OR COMPREHENSIVE ONSITE DETERMINATION METHOD (Soils and Hydrology) Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Intermediate-level Onsite Method X Comprehensive Onsite Determination Method Transed# Plot# Vegetation Unit#/Name: Sample#within Veg. Unit: SOILS Series/Phase: Gravelly sandy loam Subgroup2 (EvB-AgC) Is the soil on the hydric soils list? ' YES NO X Undetermined Is the soil a Histosol? YES NO X Histic epipedon Present? YES NO Is the soil mottled? YES NO X Gleyed? YES NO X Matrix Color. 10YR 3/3 Mottle Colors: None Additional hydric soil indicators: Saturated sandy gravelly loam Comments: Located in roadway ditchline area adjacent to Duvall Avenue. Extremely compact soils HYDROLOGY Is the ground surface inundated? YES X NO Surface water depth: Is the soil saturated? YES X NO Depth to free-standing water in pit/soil probe hole? surface Mario other field indicators of surface inundation or soil saturation below: , Oxidized root zones Water-stained leaves Water marks Surface scoured areas Drift lines Wetland drainage patterns Water-bome sedimental deposits Morphological plant adaptations Additional hydrologic indicators: Percent of dominant species that are OBL,FACW and/or FAC? 100 Is the hydrophytic vegetation criterion met? YES X NO is the hydric soil criterion met? YES NO X Is the wetland hydrology criterion met? YES X NO Is the vegetation unit or plot wetland? YES NO X Reason for jurisdictional decision: Failed to satisfy mandatory criteria. Site appeared to be constructed ditchline which has not had vegetation maintenance recently and which ponds water as a result of the compact nature of the soils. SAMPLE PLOT SP-16 DATA FORM INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD VEGETATION UNIT SAMPLING PROCEDURE Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Vegetation Unit#/Name: Herb Species Indicator Percent Cover Midpoints of Rank? Status Areal Cover Class Cover Class 2. - 3. — 4. 5. _-- 6. - - 7. - 9. 10. 12. - Shrub Species 13. Spiraea douglasii FacW 100 14. - - 15. 16. _ 19. -- 20. 21. 22. - Sapling Species 23. Populus trichocarpa Fac _ 30 24. 25. _. 26. 27. Tree Species 28. ------- 29. 30 Sum of Midpoints Dominance Threshold Number Equals 50% X sum of Midpoints 1. Cover classes(midpoints):T<t%(none);1 =1.5%(3.0);2=6-15%(10.5);3=16.25%(20.5);4=26-50%(38.0);5=51-75%(63.0); 6-76-95%(85.5);7-96-100%(98.0). 2. To determine the dominants,first rank the species by their midpoints. Then cumulatively sum the midpoints of the ranked species until 50%of the total for an species midpoints is immediately exceeded. All species contributing to that cumulative total(the dominance threshold number)plus any additional species having 20%of the total midpoint value should be considered dominants and marked with an asterisk. DATA FORM SAMPLE PLOT SP-17 INTERMEDIATE LEVEL ONSITE DETERMINATION METHOD OR COMPREHENSIVE ONSITE DETERMINATION METHOD (Soils and Hydrology) Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave, and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Intermediate-level Onsite Method X Comprehensive Onsite Determination Method Transect# Plot# Vegetation Unit#/Name: Sample#within Veg. Unit: SOILS Series/Phase: Gravelly sandy loam Subgroup2 (EvB-AgC) Is the soil on the hydric soils list? YES NO X Undetermined Is the soil a Histosol? YES NO X Histic epipedon Present? YES NO Is the soil mottled? YES __ NO 7 Gleyed? YES NO X Matrix Color. 10YR 3/2 Mottle Colors: 10YR 4/6 Additional hydric soil indicators: Comments: Located in roadway ditchline area adjacent to Duvall Avenue Extremely compact soils HYDROLOGY Is the ground surface inundated? YES NO X Surface water depth: Is the soil saturated? YES NO X Depth to free-standing water in pit/soil probe hole? Mark other field indicators of surface inundation or soil saturation below: Oxidized root zones Water-stained leaves Water marks Surface scoured areas Drift lines Wetland drainage patterns Water-bome sedimental deposits Morphological plant adaptations Additional hydrologic indicators: None Percent of dominant species that are OBL,FACW and/or FAC? 100 Is the hydrophytic vegetation criterion met? YES X NO Is the hydric soil criterion met? YES X NO Is the wetland hydrology criterion met? YES NO X Is the vegetation unit or plot wetland? YES NO X Reason for jurisdictional decision: Failed to satisfy mandatory criteria. Site appeared to be constructed ditchline which has not had vegetation maintenance recently. There were no indicators of current hydrologic support. It SAMPLE PLOT SP-17owl DATA FORM INTERMEDIATE-LEVEL ONSITE DETERMINATION METHOD VEGETATION UNIT SAMPLING PROCEDURE Field Investigator(s) WDI -Dave Risvold Date: 4/17/95 Project/Site: Duvall Ave. and 4th Street- Renton State: WA County: King Applicant/Owner. Dean Tibbott Vegetation Unit#/Name: Herb Species Indicator Percent Cover Midpoints of Rank2 Status Areal Cover Class Cover Class 1. Dactyis glomerata FacU 20 3 20.5 1 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. Shrub Species 13. Spiraea douglasii FacW 100 7 98.0 1' 14. Rubus procerus FacU T 0.0 15. Cytisus scopanus FacU 5 1 3.0 2 16. 19. - 20. 21. 22. Sapling Species 23. Populus trichocarpa Fac 30 4 38.0 1' 24. Salix sitchensis FacW 15 2 10.5 2 25. 26. 27. Tree Species 28. 29. _ 30 Sum of Midpoints 170 Dominance Threshold Number Equals 50% X sum of Midpoints 85 1. Cover classes(midpoints):T<1%(none); 1 =1-5%(3.0);2=6-15%(10.5);3=16-25%(20.5);4=26-50%(38.0);5=51-75%(63.0); 6=76-95%(85.5);7=96-100%(98.0). 2- To determine the dominants,first rank the species by their midpoints. Then cumulatively sum the midpoints of the ranked species until 50%of the total for all species midpoints is Immediately exceeded. AU species contributing to that cumulative total(the dominance threshold number)plus any additional species having 20%of the total midpoint value should be considered dominants and marked with an asterisk.