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HomeMy WebLinkAboutSWP272924 UU moot Z. ii 4it OF, tie ilk f will Now- MIN re � �! �•AsWIl��� �\� \` ��"j �I�M•�IIIII �. C N i Sep 10 02 02: 44p TOLIMA ENGINEERS 425251OG25 p . 1 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL o A licensed septic system designer or suitably trained person working under the supervision of a licensed Professional Engineer shall make an inspection of the soil after the system is excavated, before the trenches are filled with rock to confirm that suitable soils are present. Method of Analysis/Length of Roof Downspout Infiltration Trenches The length of trench required is based on the U.S.D.A, soil texture class, the roof area and the site location, using Table 4.5.113. The length of trench required is determined by dividing the roof area by 1000 and multiplying by the unit length I from the chart for the soil type and multiplying the result by the regional scale factor k shown in Figure 4.5.1 D. The trench length L is computed using the following equation: , z� L = (AR/1000)(I)(k) _ 0 0 (6U)�I / ouch Where: AR = area of the roof tributary to the system, W. (Note: a typical single-family residence has a roof area of approximately 2,000 ft'.) I = the unit length of trench required per 1,000 ft' of roof area from Table 4.5.1 B, ft-' k = the regional scale factor from Figure 4.5.1 D. TABLE 4.5.1E INFILTRATION TRENCH LENGTHS FOR RESIDENTIAL ROOF DOWNSPOUT INFILTRATION SYSTEMS Soil Texture Class (U.S.D.A.) Lineal Feet of Trench per 1000 Lineal Feet of Trench ft' of Roof - Sea Tac per 1000 ft' of Roof - Landsbur 1. Coarse sands or Cobbles 15 20, 2. Medium sand - 25 30 3. Fine sand, loamy sand 00 75 4. Sandy loam 100 125 5. Loam 150 190 Example: Proposed residence located at Kent East Hill Roof area (AR) = 2,000 square feet; Soil Texture Class = loamy sand; From Table 4.5.1 A, 60 ft trench/1000 ft,' of roof, from Figure 4.5.1 D k = 1.0 L = (2000/1000)(60)(1.0) = 120 ft Post-iV Fax Note 7671 Date -'I &: #of (Note: could be accomplished by two trenchE 1 pages _6... To Pile" V h h From Co./Dept.j1- -, r Co. t Phone# �•c�+w Phone# Fax# . f /1^ Z Fax# Z .7 r, — r0 4.5.1-3 11/94 Sep 10 02 02 : 44p TOUMA ENGINEERS 4252510625 p. 2 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL FIGURE 4.5.IA U.S.DA SOIL TEXTURE TRIANGLE Textural Triangle U.S.D.A. 100% cloy 90 10 80 20 70 _ �/ �' 30 N boy 60 ----�+----� --- Y---- 40 ll�� 50 �l 50 �_u\ _� ---fc--- Silt i V \ i' �� /' \� 'Clay \ / n�d C so 40 Clo Q�<C) - ��\ Cloy\ �' // CIa �/ --- 0 30 ---��---`V-- -�F-Loam Y-- _Lq9 7 Sandk Clay /loom m -- ---\� / --�'�/--- 80 20 / iE tF \v� Silt\ /' �� i Laam% ---- ---- 90 _ --x- x .. 10 LdbM� / �\ i �\ // Silt 100% Silt 100X sand 90 80 70 60 50 40 30 20 10 Percent SAND 4.5.1-4 11/44 City of Renton InterOff ice Memo To: Mike Dot/s�o , Surface Water From: Jan Illian` x7216 Paul Lumbert's Project Date: July 15, 2 Subject: Edmonds Plat Storm Drainage Report & Geo Tech roject Number 2924 Mike: Here is a copy of the Storm Drainage Report & Geo Tech for your files. .#' STORM'DRAINAGE REPORT PROPOSED EDMONDS PLAT EDMONDS AVENUE NE & NE 12TH STREET SECTION 8, T. 23 N, R. 5 E. W.M. RENTON, WASHINGTON 98055 RENTON LUA-00-075 5v' F,W s/yt CITY OF RENTON FOR: RECEIVED Mr. Wendell Woodell APR 1 6 mi 618 Park Ave. N. Renton, WA 98055 GUSTQw--,-v,tHVICE MARCH, 2001 JOB NO. 719-008-001 H. C� OF WAS Prepared by y Touma Engineers 6632 S. 191 ST PI, Suite E-102 Kent Wa. 98032 q�c a7o �,. PH. 425-251-0665 Fax 425-251-0625 _"_�� EXPIRFS 6/22/ 1 TABLE OF CONTENTS Pages 1. PROJECT OVERVIEW 1-3 11. CONDITIONS & REQUIREMENTS SUMMARY 4-5 111. OFF-SITE ANALYSIS G-7 IV. FLOW CONTROL & WATER QUALITY 8-24 V. CONVEYANCE SYSTEM ANALYSIS AND DESIGN 25-26 V1. SPECIAL REPORTS AND STUDIES 27 Vll. BASIN AND OTHER COMMUNITY AREAS 28 V I l l OTHER PERMITS 29 IX. EROSION/SEDIMENTATION CONTROL DESIGN 30 X. BOND QUANTITIES WORKSHEET 31 X1. MAINTENANCE & OPERATIONS MANUAL 32 1. PROJECT OVERVIEW This project involves about 1.78 acres in the northeast quarter of Section 8, Township 23 North, Range 5 East W. M. The present zone designation is (RIO) with about 17 lots allowable (1.78 x 1 Odu/acre). The proposal is for the creation of a 16 lot "Fill in" subdivision on this property. Edmonds Ave. NE on the east was developed with 44' of paving, curb, gutter, and 5' sidewalk. NE 12"' street on the north has 22' to 24' of existing asphalt road without curb, gutter or sidewalk. NE 121h street will be developed with 32' total width of asphalt paving, curb, gutter and 5' sidewalk. The site can accommodate 16 lots with frontage along Edmonds Ave. NE., that will be serviced from a private alley. The new alley road will have 20' feet of asphalt with an inverted crown to help control the surface runoff. The site topography slopes down from northeast toward the southwest. Slope grades along Edmonds Ave NE are generally steep to moderate about 20% to 50%. The slopes flatten toward the southwest and range from 10%to 20%. The steep slopes (40%) along the east portion of the site most likely originated with fill being placed in conjunction with the shoulder construction for Edmonds Ave. NE. These slopes will not be classified as protected as they are less than 15 feet in vertical. The existing site was cleared and logged some years ago with only brush and small cottonwood and alder trees less than 6" caliper now present. We plan to collect the surface runoff from the added asphalt surfacing and direct it through a wetvault on the property. The existing soils as indicated by the King County Soil Survey are InC (Indianola), and RdC (Ragnar). These soils are listed as type"A" and "B" soils, suitable for roof infiltration. This soils information is substantiated by the geologist report prepared by Terra Associates. Our preliminary studies indicate that less than 0.5 cfs of peak rate runoff increase will be generated for the 100 year storm. The asphalt paving will be directed through a wetvault for water quality mitigation. REVIEW OF RESOURCES 1. Vicinity Map 2. King County Soil Survey Mapping. 3. City of Renton Zoning and Subdivision Ordinances Pg. - 1 li 48 I 1 a I LQ 228 1 213 14 oI '52 3 I I ZS2 24 --►.+ I n r uz 3 i' a L 12.03 501, N.E.e14TH ST. .s „ I _ 8 3o '0c, : I t z M Op ! Ic i __.3 2 10 �39 -f b 1 �I I; I° tzv."1 .f1 at '13'^"' IF— 0 13 W JI i 229 ILi Sca l r r 2cx, i' _ 96.3 I;a I W I 2 3 ^ S G1 Q V J1� I b Qz 3 161 IT— Z1�. r o 13 N 1 /0117 01 ` �I 1V \\ IL R gl °, sc h� 14� I ' • \271 75 Ar.q ., 80.9, 7 - --r • -- -__ - __ - - I -_ - N. E-- -''i2TH�- -�ST: ,ViZ>Gl• _s .,. •'ai 1 .. ;'" _ 1.:N, y /� a og 73 00 (I O C I I 1 W M I I '0 �i� l.�i .,.f I A .�l I 1 C17. 2 t4S 1 1•! 1 ^ I n N 'V; Z 1 �� -}c, 11 Ll.IB3 1.L.: S .a. -� 'T.:.;47 L!.'9G 1Ln kn •;. ,a nE Z 1 Z�I OMEGA 32= �� Q � _ �,2 EI! uUP�AEN'i •Q w \ �'� Al. E. ': •n�,aLK•. 3 Ac. ct �.'6.;c.' ;o I.. LL-11 ^.o�Ac — .I 9.)7 I�I so 3 1 r'! 1 a. LAUREi10E Jo�llr I1;1 R E 5 T g 147 O2 E N 0o s I" N, 1146 �i \�..\ 1•-I El 1141 LI4.26 °ii ,nII.3 10 L��/z -[.. 51a j''Q^ :� is IG 11 9 s — _3951 11-43 ni �I13$' :4, 900' .Iw aS�a Z OUT ES Ac ,` —4�=-- T I' 30 c �C ;11IV 1`S I Q H!6H A Z3.la J N i E ? tl_I a8—� 0 10 (i I 3 \j f�1� II w ';I I — � , Q 0. e'a-7-ac.12 W'UNSET..,HEl J " TS56 UNITS 13 j '.1 O �`\p •0 �\ �I1 5} >Q AD ~a HEIGHTS 3MINIUM tau r A- A INIUM 'c61 A68 d0 ooGf'�o / !951 z r 5 nl G T W 0 1 IOTH PL. I ICE] 1 ,!02, n a ,,�•ooj`�i 1 jog _� [nr II . �i b'T. .�,� ^ 1` 9 --7-7— _------ y .3 I '� I CP A l6 OU M j F�lea5ure B ' \ ZU IB I ) 5�� �� = J• , Point 21 • eeh. t Hills Is Par Psi rest Po k Am8 t ��G •�• I tlr U AmC _ aZ -, InC _ AkF Bh Aa" i "') +-' (AkF ---- pp�BN • 6 KPD --- 29 2 3 Z 'AgC t1i 42 BeC l— - Q@, Cs KPB• ' s AgC '• . 'Pin — NeWPO AgD 32 EwC s - _-—,, Hills! Ur Ag$ s InA i ABC - ■ , wFl-, -- I - -U- Gol(Course ta r 0♦ P; AmR �� s KDDr BeC 3 J C AgD._ 3 k PDM Bti AgC y.�. B AmC.r 1 EvC Be Sh �• I ABC EWC BM May a KPC YQ. •EvC y \ e'O idQe Sch 109 ♦ ��' OvD B A D- 1y g '• •• • u' No ti '� ABC 1 BM �. 'A8C �,vi• ti i •1 605 KPB 6 •`I • �• J:� Sm \ O A8C s) '`:;.. 1 \• .AgC •I �n �O m AgD AgD • " •� ; `A€ L Kennydale I y^', Agc :! •IfiC AkF •' i AkF • A8C EvB /C I AkF V. .V;is I I Ber- Coleman Poin Q :r: Pv GRAVEL. AkF 306, A 'InA' 1 — �:.. — ;l s ,•, '.. AgC 1 B C '!ski v e , BM Ev6 { m a BM 0� o• n p �' ' .8C If If to AkF n � z_ �mC t Sin i 1./All IfinCf- f , Ag • �; / .� EvC Mawr �kF • .L�, _ MU F1$,� t BDY n'• ' ,•.c -� I R ry ir. ' '4 FsdC•• r ^ D� — •`Age ant• "r��' ' + (F>L i'i Plani .•I �.�L 11J:r /�1Ir� , _ EvC Ur '�� E. RENTON 1.9 M/. 1290" (Joins sheet 1 I) HOC - RENTON I.7 MI, ^ 10, ^ Scale 1:24000 —3 So ) L 1_1 4P - -- — - -- ,)000 10000 1,,,.1 If. CORE AND SPECIAL REQUIREMENTS CORE REQUIREMENT 91: DISCHARGE AT NATURAL LOCATION The allowable outflow from the site will be discharged to its natural location. The lowest elevation for the basin is approximately 275'. CORE REQUIREMENTS #2: OFF-SITE ANALYSIS Refer to off-site analysis on subsequent pages. CORE REQUIREMENTS #3: RUNOFF CONTROL Calculations are provided on subsequent pages addressing peak runoff. Sizing for peak rate runoff control facility and its routing do not appear to be required. Water quality control will be provided in a form of a wet-vault. CORE REQUIREMENTS #4: CONVEYANCE SYSTEM The conveyance system will be designed using the rational method. CORE REQUIREMENTS #5: EROSION/SEDIMENTATION CONTROL PLAN The Erosion/Sedimentation control facilities will consist of filter fabric fences to be placed along the west and southhwest boundary of the site. CORE REQUIREMENT #6. - Maintenance and operation Maintenance involves having on-site catch basins cleared fi-om sediments when necessary. CORE REQUIREMENT #7. - Bonds and liability SPECIAL REQUIREMENTS: THOSE APPLICABLE TO PROJECT I. Critical Drainage Area- The drainage basin is not part of any critical drainage area. 2. Compliance with existing Master Drainage Plan—N/A 3. Conditions Requiring Master Drainage Plan—N/A 4. Adopted Basin or Community Plans—N/A, However, the site is drains to Lake Washington via Sunset boulevard 5. Special Water Quality Controls - The proposal will create 0.57 acres of new asphalt. The special water quality controls will be in the form of wet-vaults. See section IV of this report. Pg. - 4 6. Coalescing Plate Oil-Water Separators—N/A 7. Closed Depression—N/A 8. Use of Lakes, Wetlands, or Depressions for Detention—N/A 9. Delineation of 100-year Flood Plain —N/A 10. Flood Protection for Type 1 and 2 Steam —N/A 11. Geotechnical Analysis and Report — Geotechnical study is being prepared in conjunction with this application. 12. Soil Analysis and Report— Geotechnical report has been prepared for this site and addresses the soil classifications and stability. 13. A Wetland Mitigation Report —N/A. Pg. - 5 III. OFF-SITE ANAYSIS FIELD INSPECTION The field inspection of the site was performed in April, 2000. The property is presently vacant. Edmonds Ave. NE is developed on the west and east with curb, gutter, sidewalk, and storm drainage. No surface runoff enters the site from Edmonds Ave. NE. The street to the north is NE 12°i street. This existing street has a thickened asphalt edge and/or curb along the south edge, which contains the street surface runoff. The surface runoff flows westerly along this asphalt curb to the west edge of our proposal. Riprap has been placed along the paving in front of the PSE substation and directs runoff to the west. DOWNSTREAM The site slopes to the southwest and south. There was no evidence of any concentrated flows leaving the site. The existing right of way abutting to the south is Sunset Boulevard (SR 900). Adjacent to the southwest corner of the site within the right of way for Sunset Blvd. is an existing catch basin about 7 feet deep. This conveyance pipe carries runoff from the drainage areas lying to the east of the site. Presently a 24" diameter concrete pipe enters this CB from the east and exits westerly with about 200' of 27" diameter concrete pipe at about 2.5% to a type 2 catch basin. From that point, a 30" pipe continues to the southwest along the northerly margin of Sunset boulevard. See the attached downstream"Drainage Plan Map" from the There does not appear to be overflow or flooding problems within '/4 mile downstream of the proposed site. Pg. — 6 � L T. '22)?I\ 10 w. , u-ozo- (b) se e1101 1 D s ro « o r r /i//Tqo 6/xher lNilh No�'ive Moterio/ ORA/NA6E L f SZWO ReQui�ed / / Svb yre de a i finished G�adi A, Riprap O C&lch D&sm 'eiiai�—� Gears/ dac,Efi// ' A/onha✓e i :iroin Underdiein Pipe q 31 New Construction Storm Drnin —_ —` Ditch I6"1 ou I as Ian 16"1 Z7 Stiucfure �D Note: Use Common trench as detailed above Not& Number - STORAf SEWER < UNWRORAIN DETAILS Wheh d'rt`+`d by the Engineer G"UD.R P/og Pipe(0ee Joeeio/ �rorivia•v) EAbandon !See Special P�orisions) c P D.P. Groin ips raina9 _ ___- -------- __ a�aP E'ostt°9 O o See Orire !✓ay Qetaik Jhe2t,_U_ 11 8 2T PCSP - \\\ ..- f.fi - o e \ Underdiein Pipe Sig �\\ 2�,QC 13 \ 30 � SC.N.D Schedo% Pipe � Ile 9 _ So --- \\� P ° / 7 ! * 5 C M.P. Corruyoted Afeta/ Pipe A !21FC5 ��— i 32 12 - - 15 SC.P.A. S7ee/ C4V/vv1 Pip& Arch C.C.P Conciere !a/refs Pipe �c'S,o 'ems � .�D�( i ! I • _- .it � 14 N 18 y P.C.C.P. P/om CanereYe Cv/reif Pie f �{ I I P C.C.P. Reinforced Conciste _,if Wlth Pump gP/� 3 P 20 =teal Drov.) P/o/n Coneiete Surer pe Pi R.C.SP. Reinforced Concrete Sewer 0Pe r// • I�� �� �\ ,f'S.R Jtee/ Surer Pipe v"- 7. ,f1 a9.79.5 POC= \\ 19 ``�sq 6- C/'W10 Cos/ ?On {✓o/4-Pipe 116a Ave.S.E.20.06,07 POT. \ ooA 4 3 i /•, . // /r,. S 21 rDCSP� Adj: Yv/re C/aomtrrr �- r0 27 < Ad. Fie /lydionf 00 Station ouanti ivl Sto-ri on 25 uonti \� Y12q Bq 29 6G $ AdT 0, fe1xa,,e Woe,- Meters • 6 c' Oo PPx Adj. Valve Chambers 127,40 LT 1 r yo. 1116u 19.05 Lt 1 113D•25 Lt 1 26 / 1 142 •50 LT 1 Wafl 28 176• 95 Lt yP 164 90 Lt o /19�\, , • S Adj. Valve Bores 1 3 ST.4. A39s/7.60 ,007. A49+15 Lt. 1 123.35 It A49.65 Rr 1 1133.58 Lt 3EG//V/V//VG OF AWO✓ECT 116m 18.90 LT. i 1 146.50 Lt i AEG/NN/NG OF U-020-j(6) _ iib� 21+39 Rr. 1 148.50 Lt. 116t' 21.81 Lt 1 156. 60 Lt. 1 ( �• \ A62+75 Rt I 1 172.27 LT. 2 \� A62+ BO LT. 1 178.10 LT 1 U6.10 Lr. 12m 19.55Lt. I 1 122.05 Lt 1 127+30 LT ! 7 129. 00h. 130.10 LT.. 1 I 135.60 Lt +.: I 142•30 Lt. 1 54+45 Lt 154• 55 LT. 1 - - -- -- - 160• 85 Lt, 1 164-60 Lt. 17 138 62-5.0 Rt 163.60 Lr I STU- 1 183.75LT. 1 H22+0C Rt Adj,Or Ralocott Water Meters i 116'" 21+45 Rt. I Ad Fire Hydrants 1 �I 21 801t ; I 102.55 Rt. I so 3c o 30 00 ac •90 Rt. - o0 Sca -eet IV. FLOW CONTROL AND WATER QUALITY The Preliminary Report to the Hearing Examiner for hearing January 2, 2001 states that this proposal should comply with the 1990 KCSWDM for drainage and temporary erosion control plans. The area of the plat to be developed is 1.78 acres, including asphalt paving, driveways, houses and landscaping. About 0.06 acres along NE 12°i street, will be widened with curb, gutter and sidewalk. The new added asphalt paving and driveways will be directed through a wet-vault for Water Quality measures. The roof runoff from the new houses will be infiltrated into the type "A" or`B" soils. Thus the roof area will be considered as a grassed area for hydrograph calculations. Pre-Developed Conditions Pervious Brush and Trees 1.84 acres cn=74 Post-Developed Pervious Lawn& Landscaping 0.92 acres cn=77- House Roof= Lawn(infiltration) 0.59 acres cn=77 (16 x 1600sf)/43 560 = 0.59 ac. Impervious Asphalt + sidewalk 0.33 acres cn=98 7 The attached time of concentration sheet indicates that the Pre-developed travel time is 7.19 minutes and the Post-developed travel time is 6.95 minutes. The King County Hyd. Program was used to develop the hydrographs for this report. The hydrographs indicate that there is less than 0.50 cfs. increased 100-year peak flow between the Pre-developed and Post-developed conditions. See page 1.2.3-5 of the King County Surface Water Design Manual (KCSWDM), for negligible peak runoff rate increase. WATER QUALITY The wet-vault permanent pool will be sized per page 1.3.5-1 of the KCSWDM. The design water surface must be a minimum of one percent of the impervious surface area within the contributing drainage sub-basin. The design volume must be the hydrograph runoff volume of the mean annual storm event. This is approximated by using 64% of the 2-year for storm input. Wet-vault surface area= 0.57 acres (43560) x 1% = 248 square feet. (minimum) Wet-vault volume= 990 cubic feet. (minimum) Try a vault that is 10' wide, 34.33' long, and contains 3' of wet vault with l' of sediment storage. Pg. — 8 Assuming 2 - 8" thick partition walls, the volume will be I0'x33'x3' = 990 cubic feet, the required amount. The required surface area is about 248 square feet. This arrangement will yield 330 square feet of surface area. About 10% to be in bay 1 and the remainder split evenly, for a total of 3 bays. If the first is 4' long, the others will be 14.5' long. Size the water qu rty orifice based on the 2-year dev. Peak flow of 0.34 cfs. H= 278.60— 27f.76 = 1.84'. See the attached calculation sheet which indicates that the orifice should be 3.04"in diameter. The calculated peak 100-year developed flow is 1.06 cfs. The calculated depth of flow in a 12" pvc pipe is 0.34'. Therefore the bypass pipe invert elevation has been set 0.34' below the top of the restrictor overflow elevation. See the pipe flow calculation on page 25 of this report. ROOF INFILTRATION The soils are classified as Type"A" soils, with the existing being made up of predominately medium sand. Per the KCSWDM table 4.5.lb medium sands require 25 linear feet of trench for each 1000 square feet of roof area. s�7r Therefore a roof area of 1200 square feet will require; 1200/1000 x 25' = 30' of trench. BIO-FILTRATION We have accommodated the bio-filtration action within the wetpond as designed above. Pg. - 9 STORM DRAINAGE TIME OF CONCENTRATION FOR EDMONDS JOB TOTAL AREA 1.78 ACRES - ENTIRE PROPERTY BASIN AREA 1.84 ACRES - ON SITE AND OFF SITE SOIL TYPE InC, RdC Indianola predominately Type "A" EXISTING CONDITIONS OPEN AREAS 1.84 ACRES CN 74 PERVIOUS AREA 1.84 CN 74 POST DEV. CONDITIONS LANDSCAPING 0.92 ACRES CN 77 HOUSE ROOF = LAWN 0.59 ACRES CN 77 16 x 1600 SF=25600/43560=.59 AC ASPHALT + CONCRETE 0.33 ACRES CN 98 PERVIOUS AREA 1.51 ACRES CN 77 IMPERVIOUS 0.33 ACRES CN 98 TIME OF CONCENTRATION - PRE-DEVELOPMENT - FOR 2-YEAR, 24-HOUR STORM DESIGN i SHEET FLOW- ONSITE �rx )k`'v MANNING- RANGE 13 OVERLAND-L 60 FEET PRECIPITATION-P 2 INCH SLOPE - S 0.15 FT/FT T1 = 7.19 MINUTES = (( -1 TOTAL TIME - PRF,- QF-VELOPMENT 7.19 TIME OF CONCENTRATION - POST DEVELOPMENT - FOR 2-YEAR, 24-HOUR STORM DESIGN SHEET FLOW- ONSITE MANNING- SURFACE 0.15 OVERLAND-L 140 FEET PRECIPITATION-P 2 INCH SLOPE - S 0.24 FT/FT T1 = 6.00 MINUTES CONCENTRATED FLOW- ONSITE GUTTER 0 FEET K- VALUE 42 SLOPE - S 0.18 FT/FT VELOCITY-V 17.82 FPS T2 = 0.00 MINUTES PIPE 420 FEET K- VALUE 42 SLOPE - S 0.031 FT/FT VELOCITY-V 7.39 FPS T3 = 0.95 MINUTES TOTAL TIME - POST DEVELOPMENT 6.95 �u J f� EDMONDS AVENUE NE :7A v tx cs Dr w E.-% a6!-!' E S= 14,W- AE IL Iw - - - - 9 G/17FR s,awffwsr I{a' L=160' 1478 ! 78 V a 2,m57 S=15X Lo N rx AREA 1.78 AC. SITE Z 0.06 AC NE. 1127H ST. / 1.84 AC. j PRE-DEVELOPED CONDITIONS .n W J � Q EDMONDS AVENUE NE GO gNatlA aC R f5 IX- I E-=Qt-d' E�L7SW-P{'Mb' EY7HOF!{ 1f�fAlp A-- i ti - - - I M M1V A97NCT. INSTALL fMWa2r arm 9�/ aW AC i t i -i !. I , I , , / JO EL—sae L UUJ ~ AREA L=420� M-2MAD / N UJ � f.78 AC. SITE S=3.1% Ld 0.06 AC NE. 112TH ST. Z i 1.84 AC. I - DEVELOPED CONDI TIONS I I � r KING COUN 'I' Y, WAS IfINGTUN, SUItFACE WATER DESIGN MANUAL, 'FABLE 3.5.211 SCS WESTERN WAS1f1NCT0N RUNOF CURVE NUMBERS SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS (Published by SCS In 1982) Runoff curve numbers for selected agricultural, suburban and urban land use for Type to rainfall distribution, 24-hour storm duration. CURVE NUMBERS BY HY OGIC SOIL GROUP LAND USE DESCRIPTION A B C D Cultivated larnd(1): winter condition 86 91 94 95 Mountain open areas: low growing brush and grasslands 1741 82 89 92 Meadow or pasture: 65 78 85 89 Wood or forest land: undisturbed 42 64 76 81 ' Wood or forest land: young second growth or brush 55 72 81 86 Orchard: with cover crop 81 88 92 94 Open spaces, lawns, parks, golf courses, cemeteries, landscaping. good condition: grass cover on 75% or more of the area 68i 80 86 90 fair condition: grass cover on 50% to 75% of the area LL7j 85 90 92 Gravel roads and parking lots 76 85 89 91 Dirt roads and parking lots 72 82 87 89 Impervious surfaces, pavement, roofs, etc. 9$ 98 98 98 Open water bodies: lakes, wetlands, ponds, etc. 100 100 100 100 Single Family Residential (2) Dwelling Unit/Gross Acre % Impervious (3) 1.0 DU/GA 15 Separate curve number 1.5 DU/GA 20 shall be selected 2.0 DU/GA 25 for pervious and 2.5 DU/GA 30 Impervious portion 3.0 DU/GA 34 of the site or basin 3.5 DU/GA 38 4.0 DU/GA 42 4.5 DU/GA 46 5.0 DU/GA 48 5.5 DU/GA 50 6.0 DU/GA 52 6.5 DU/GA 54 7.0 DU/GA 56 Planned unit developments, % impervious condominiums, apartments, must be computed commercial business and Industrial areas. (1) For a more detailed description of agricultural land use curve numbers refer to National Engineering Handbook, Section 4, Hydrology, Chapter 9, August 1972. (2) Assumes roof and driveway runoff is directed Into street/storm system. (3) The remaining pervious areas (lawn) are considered to be in good condition for these curve numbers. 3.5.2-3 2/99 5 3BUH/SCS METHOD FOR COMPUTING RUNOFF HYDROGRAPH STORM OPTIONS : L - S .C.S. TYPE-lA - 7-DAY DESIGN STORM W rr F,�lfA�1Y/ 3 - STORM DATA FILE 3PECIFY STORM OPTION: L PACs sf-'F'c1 &L (LGC�-�tiiQ/r mSi`r i 5 3 .C. S . TYPE-1A RAINFALL DISTRIBUTION 3NTER: FREQ(YEAR) , DURATION(HOUR) , PRECIP( INCHES) L , 24, . 67 ---------------------------------------------------------------------- k******************* S.C. S . TYPE-lA DISTRIBUTION ******************** k******** 1-YEAR 24-HOUR STORM **** . 67" TOTAL PRECIP. ********* ---------------------------------------------------------------------- 'sNTER: A(PERV) , CN(PERV) , A( IMPERV) ,' CN( IMPERV) , TC FOR BASIN NO. 1 L . 84, 74,0 ,98, 7 . 19 )ATA PRINT-OUT: AREA(ACRES) PERVIOUS IMPERVIOUS TC(MINUTES) A CN A CN I} 1 . 8 1 . 8 74 . 0 . 0 98. 0 7 . 2 PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT) . 00 . 00 0 3NTER [d: ] [Path]filename[ .ext] FOR STORAGE OF COMPUTED HYDROGRAPH: Lelyr SPECIFY: C - CONTINUE, N - NEWSTORM, P - PRINT, S - STOP ---------------------------------------------------------------------- -NTER: A(PERV) , CN(PERV) , A( IMPERV) , CN( IMPERV) , TC FOR BASIN NO. 2 L . 27 , 77 , . 57,98, 6.95 )ATA PRINT-OUT: AREA(ACRES) PERVIOUS IMPERVIOUS TC(MINUTES) A CN A CN 1 . 8 1 . 3 77 . 0 . 6 98. 0 6. 9 PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT) W K}-TE Y2 0-U%41-- i T_/ . 07 7 . 83 990 --Ups t4 W) -NTER [d: ] [Path]filename[ .ext] FOR STORAGE OF COMPUTED HYDROGRAPH: Ldlyr SPECIFY: C - CONTINUE, N - NEWSTORM, P - PRINT, S - STOP ;BUH/SCS METHOD FOR COMPUTING RUNOFF HYDROGRAPH STORM OPTIONS : L - S.C. S. TYPE-1A \Nl�� f: /� R �� � �. ir � r� r✓4l � aui - 7-DAY DESIGN STORM rb �} !E 3 - STORM DATA FILE . p SPECIFY STORM OPTION: ;.C.S . TYPE-1A RAINFALL DISTRIBUTION s'NTER: FREQ(YEAR) , DURATION(HOUR) , PRECIP( INCHES) ? ,24, 2 ---------------------------------------------------------------------- r******************* S.C . S. TYPE-1A DISTRIBUTION ******************** ******** 2-YEAR 24-HOUR STORM **** 2 . 00" TOTAL PRECIP. ********* ---------------------------------------------------------------------- �'NTER: A(PERV) , CN(PERV) , A( IMPERV) , CN( IMPERV) , TC FOR BASIN NO. 1 L . 84,74,0,98, 7 . 19 )ATA PRINT-OUT: AREA(ACRES) PERVIOUS IMPERVIOUS TC(MINUTES) A CN A CN 1 . 8 1. 8 74. 0 . 0 98 . 0 7 . 2 PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT) . 05 12 . 50 2336 :LATER [d: ] [path]filename[ .ext] FOR STORAGE OF COMPUTED HYDROGRAPH: L2Y ;PECIFY: C - CONTINUE, N - NEWSTORM, P - PRINT, S - STOP ---------------------------------------------------------------------- ,NTER: A(PERV) , CN(PERV) , A( IMPERV) , CN( IMPERV) , TC FOR BASIN NO. 2 .. 27 , 77 , . 57 ,98, 6 . 95 )ATA PRINT-OUT: AREA(ACRES) PERVIOUS IMPERVIOUS TC(MINUTES) A CN A CN 1 . 8 1 . 3 77 . 0 . 6 98. 0 6. 9 PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT) . 34 7 . 83 5736 INTER [d: ] [path]filename[ .ext] FOR STORAGE OF COMPUTED HYDROGRAPH: .D2YR >PECIFY: C - CONTINUE, N - NEWSTORM, P - PRINT, S - STOP � , � I -9 SBUH/SCS METHOD FOR COMPUTING RUNOFF HYDROGRAPH STORM OPTIONS : 1 - S .C. S . TYPE-1A 2 - 7-DAY DESIGN STORM 3 - STORM DATA FILE SPECIFY STORM OPTION: 1 3 .C. S . TYPE-1A RAINFALL DISTRIBUTION ENTER: FREQ(YEAR) , DURATION(HOUR) , PRECIP( INCHES) 10,24, 2 . 9 ---------------------------------------------------------------------- +�******************* S .C. S . TYPE-1A DISTRIBUTION ******************** k******** 10-YEAR 24-HOUR STORM **** 2 . 90" TOTAL PRECIP. ********* ---------------------------------------------------------------------- ENTER: A(PERV) , CN(PERV) , A( IMPERV) , CN( IMPERV) , TC FOR BASIN NO. 1 1 . 84, 74,0,98, 7 . 19 DATA PRINT-OUT: AREA(ACRES) PERVIOUS IMPERVIOUS TC(MINUTES) A CN A CN 1 . 8 1 . 8 74 . 0 . 0 98 . 0 7 . 2 PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT) . 28 7 . 83 5645 ENTER [d: ] [path]filename[ .ext] FOR STORAGE OF COMPUTED HYDROGRAPH: LE10YR SPECIFY: C - CONTINUE, N - NEWSTORM, P - PRINT, S - STOP ---------------------------------------------------------------------- �'NTER: A(PERV) , CN(PERV) , A( IMPERV) , CN( IMPERV) , TC FOR BASIN NO. 2 L. 27, 77 , . 57,98, 6 . 95 )ATA PRINT-OUT : AREA(ACRES ) PERVIOUS IMPERVIOUS TC(MINUTES) A CN A CN 1 . 8 1. 3 77 . 0 . 6 98 .0 6 . 9 PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT) . 66 7 . 83 10141 ;NTER [d: ] [path]filename[ .ext] FOR STORAGE OF COMPUTED HYDROGRAPH: LD10YR >PECIFY: C - CONTINUE, N - NEWSTORM, P - PRINT, S - STOP F . - 3BUH/SCS METHOD FOR COMPUTING RUNOFF HYDROGRAPH STORM OPTIONS : L - S.C . S. TYPE-1A - 7-DAY DESIGN STORM 3 - STORM DATA FILE iPECIFY STORM OPTION: L i .C. S. TYPE-lA RAINFALL DISTRIBUTION 9NTER: FREQ(YEAR) , DURATION(HOUR) , PRECIP( INCHES) L00 ,24,3 . 9 ---------------------------------------------------------------------- r******************* S.C . S. TYPE-1A DISTRIBUTION ******************** r******** 100-YEAR 24-HOUR STORM **** 3 . 90" TOTAL PRECIP. ********* ---------------------------------------------------------------------- P,NTER: A(PERV) , CN(PERV) , A( IMPERV) , CN( IMPERV) , TC FOR BASIN NO. 1 L . 84,74,0,98,47 . 19 )ATA PRINT-OUT: AREA(ACRES) PERVIOUS IMPERVIOUS TC(MINUTES) A CN A CN 1 . 8 1 . 8 74. 0 . 0 98 . 0 7 . 2 PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT) . 62 7 . 83 10172 'sNTER [d: ] [path]filename[ .ext] FOR STORAGE OF COMPUTED HYDROGRAPH: LE100YR SPECIFY: C - CONTINUE, N - NEWSTORM, P - PRINT, S - STOP ---------------------------------------------------------------------- 9NTER: A(PERV) , CN(PERV) , A( IMPERV) , CN( IMPERV) , TC FOR BASIN NO. 2 L . 27 , 77 , . 57 ,98, 6.95 )ATA PRINT-OUT: AREA(ACRES) PERVIOUS IMPERVIOUS TC(MINUTES) \ � A CN A CN ; 1 . 8 1. 3 3-7 . 0 . 6 98 . 0 6. 9 'A 0 PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT) 1 , 06 7 . 83 15576 ''NTER [d: ] [path]filename[ . ext] FOR STORAGE OF COMPUTED HYDROGRAPH: LD100YR SPECIFY: C - CONTINUE, N - NEWSTORM, P PRINT, S - STOP C F ' L F 1-1-1 A 1-1 s a>2 r�ioov7 D2�r1 , /�04� L�Frr�I7i��l cF F 2 $ KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUA-L TABLE 3.5.2C "n" AND IV' VALUES USED IN TIME CALCULATIONS FOR HYDROGRAPHS 'n,'Sheol Flow Equation Manning's Values(For the Initial 300 If of travel) n,' Smooth surfaces(concrete,asphalt,gravel,or bare hard packed soft) 0.011 - Fallow fields or loose soil surface(no residue) 0.05 Cultivated soil with residue cover(s <= 0.20 h/h) 0.06 Cultivated soil with residue cover(S>020 h/h) 0.17 Short prairie grass and lawns 0.15 Dense grasses 0.24 Bermuda grass 0.41 Range(natural) 0.13 ..�- Woods or forest with light underbrush 0.40 Woods or forest with dense underbrush 0.80 'Manning values for sheet flow only,from Overton and Meadows 1976(See TR-55,1986) 'k'Values Used In Travel Time/Time of Concentration Calculations Shallow Concentrated Flow (Aber the initial 300 h.of sheet Now,R e 0.1) k, 1. Forest with heavy ground litter and meadows(n=0.10) 3 2. Brushy ground with some trees(n-0.060) 5 3. Fallow or minimum tillage cultivation(n -0.040) 6 4. High grass(n = 0.035) 9 5. Short grass,pasture and lawns(n-0.030) 11 6, Nearly bare ground(n=0.025) 13 7. Paved and gravel areas(n=0.012) 27 Channel Flow(Inte(mluent)(At the beginning of visible channels.R-0.2) k, 1. Forested swale with heavy ground I41or(n - 0.10) 5 2. Forested drainage course/ravine with defined channel bed(n=0,050) 10 3. Rock linedwaterway(n=0035) 15 4. Grassed waterway(n-0.030) 17 5. Earth-lined waterway(n=0.025) 20 6. CMP pipe(n=0.024) 21 7. Concrete pipe(0.012) 42 8. Other waterways and pipes 0.508/n Channel Flow(Continuous stream,R 0.4) k� 9. Meandering stream with some pools(n-0.040) 20 10. Rock-lined stream(n=0.035) 23 11. Grass-lined stream(n=0.030) 27 12. Other streams,man-made channels and pipe 0.607/n" "See Chapter 5,Table 5.3.6C for additional Manning$'n'values for open channels 3.5.2-7 1/90 .. r w 5 MA e Lie Wall IL Ki I • DFULAI DE I[oil]'lip Kill KIIIJ its iJ 1 1 � 1 SIMPLE ORIFICE CALC'S d=((36.88Q/(h)^.5)^.5 1 PER KING COUNTY SECTION 4.4.7A WATER QUALITY ORIFICE CALCULATION LOWER ORIFICE H=ft. 1.84 ft Q= cfs 0.34 cfs DIA-IN = 3.040 in. Circular Channel Analysis & Design Solved with Manning' s Equation Open Chann(-J - Uniform flow Worksheet Name: edmonds Comment : pipe flow depth Solve For Actual Depth Given Input Data : Diameter. . . . . . . . . . 1 . 00 ft Slope. . . . . . . . . . . . . 0. 0100 ft/ft Manning' s n. . . . . . . 0 . 011 9A K rL� 0 Discharge. . . . . . . . . 1 . 06 cfs Computed Results : 1 D - yC-A 2 Depth. . . . . . . . . . . . . 0 . 34 ft v FF Sr 7- i=c,P- Velocity. . . . . . . . . . 4.47 fps Flow Area. . . . . . . . . 0 . 24 sf Critical Depth. . . . 0 . 43 ft Critical Slope. . . . 0 . 0042 ft/ft Percent Full . . . . . . 34 . 20 % Full Capacity. . . . . 4. 21 cfs QMAX @. 94D. . . . . . . . 4. 53 cfs Froude Number. . . . . 1 . 57 (flow is Supercritical ) Open Channel Flow Module, Version 3 .4 (c) 1991 Haestad Methods , Inc. * 37 Brookside Rd * Waterbury, Ct 06708 �y. zW V. CONVEYANCE CALCULATION The calculated 100 year peak flow from this site is 1.06 cfs. See the calculation on page 27 of this report, which shows that a 12" pipe will carry 4.15 cfs when flowing at 93% full, maximum capacity. Pg. —25 Circular Channel Analysis & Design Solved with Manning' s Equation Open Channel - Uniform flow Worksheet Name : EDMONDS PLAT Comment : FULL PIPE FLOW Solve For Actual Discharge Given Input Data : Diameter . . . . . . . . . . 1 . 00 ft Slope. . . . . . . . . . . . . 0 . 0100 ft/ft Manning' s n. . . . . . . 0 . 012 Depth. . . . . . . . . . . . . 0 . 93 ft Computed Results : Discharge. . . . . . . . . 4 . 15 cfs Quo p _ �, 0to CC Velocity. . . . . . . . . . 5 . 45 fps Flow Area. . . . . . . . . 0 . 76 sf Critical Depth. . . . 0 . 86 ft Critical Slope. . . . 0 . 0107 ft/ft Percent Full. . . . . . 93 . 00 % Full Capacity. . . . . 3 . 86 cfs QMAX @. 94D. . . . . . . . 4. 15 cfs Froude Number. . . . . 0 . 79 ( flow is Subcritical) Open Channel Flow Module, Version 3 . 4 (c) 1991 Haestad Methods, Inc. * 37 Brookside Rd * Waterbury, Ct 06708 T'� , -- zU VI. SPECIAL REPORTS AND STUDIES Pg. - 27 VII. BASIN AND OTHER COMMUNITY AREAS Pg. -28 VIII. OTHER PERMITS Structural permit for the concrete wall along Edmonds Ave. NE Residential Building Permits Pg. —29 IX. EROSION/SEDIMENTATION CONTROL DESIGN The temporary erosion plan will be designed to reduce the chances that any construction related silty runoff will leave the site and affect downstream facilities. The amount of cleared area for road construction will be similar to the 2-year developed hydrograph, which will produce a peak flow of about 0.34 cfs. From pages 5.4.5.1-1 of the 1990 KCSWDM a sediment trap for less than 3 acres development should contain a minimum surface area at 3.5' depth to allow settling of the silt particles. The minimum surface area is to based on the formula; SA= FS (Q2/VS) where FS = Safety Factor= 2.0 Q2 =Peak 2-year developed flow V2 =Particle settling velocity= 0.00096 Vs SA= (2) (0.34)/ (0.00096) = 708.3 SF. Required 3:1 side slopes 0.0' - 3' x 10' 1.0' - 9' x 16' 2.0' - 15' x 22' 3.0' -21' x28' 3.5' — 24' x 3 V SF at 3.5' deep 744 SF—OK 4.5' — 30 x 37' V freeboard The sediment trap should be constructed at the lower portions of the site Pg. — 30 J IX. BOND QUANTITIES Pg. - 31 X. MAINTENANCE.AW OPERATIONS Pg. - 32 TERRA ASSOCIATES, Inc, Consultants in Geotechnical Engineering, Geology and Environmental Earth Sciences MEMO To: Mr. Tom Touma Junc 21,2001 Touma Engineers&Land Surveyors Project No.T-421-1 From: John Sadler Terra Associates,Inc. Subject: Geotechnical Consultation—Downspout Infiltration Feasibility Edmonds Avenue Site Renton,Washington Reference: Preliminary Geotechnical Report,Edmonds Avenue Site,by Terra Associates,Inc.,dated September 27, 2000 Tom- As requested, we reviewed our geotechnical report for the subject site to evaluate the potential for downspout infiltration on the individual lots. Based on our conversation with you, we understand that the lot infiltration trenches would be constructed near the access road in the western portion of the site, and would be designed using criteria outlined in the 1998 King County Surface Water Design Manual (SWDM). We observed fine to medium grained sand in five of the nine test pits excavated at the subject site. In general,we encountered the sand in the western portion of the site; however, we did not encounter sand in Test Pit TP-7, located in the vicinity of Lot 13_ At this location, we encountered approximately five feet of silt and clay overlying very dense glacial till. We did not encounter groundwater in any of the test pits. Based on our observations, it appears that subsurface conditions in the westem portion of the site are generally favorable for downspout infiltration, except in the vicinity of Lot 13, which is underlain by relatively iinpermeable silt, clay, and glacial till. Based on the spacing of the test pits across the site, the presence of the sand should be confirmed at the infiltration trench locations. We trust that this information meets your current needs. Please call if you have any questions. John Sadler 12325 Willows Road, Suite 101, Kirkland, Washington 98034 M.__., (A')c\ 0111 7777 • my r47S1971-4334 • terra®terra-associates_com 'I'MIMA ENGINEERS AND LAND SURVENORS LETTER OF 6632 South 191`' I'lace, Suite E-102 TRAN.S'lIa1TTA1. Kent, Washington 98032 Phone 425-251-0665 Fax 425-251-0625 '10 City of Renton FROM Tom Touma DAI1: 3/6/02 Edmonds Plat A I--1-N Mr. Paul Lumbert We are transmitting the following documents: Lopies Date _ _ Descriptron 1 Copy of Geotechnical Report ON Remarks: cRY Of Ed R�pR �� 2901 For your use as requested. U`�D,NG��v�g�ON B cc, Signed _ tom Touma, PE/PLS .. �M PRELIMINARY GEOTECHNICAL REPORT Edmonds Avenue Site Edmonds Avenue NE and Sunset Boulevard NE Renton, Washington Project No. T-421-1 Terra Associates, Inc. r C 1 a4,t'a,S Soh 4`.ir y r s Prepared for: Cambridge Homes Kirkland, Washington September 27, 2000 ..;...... :f ... .. ..... :. TERRA ASSOCIATES, Inc. Consultants in Geotechnic<d Engineering, Geology and Environmental Earth Sciences September 27, 2000 Project No. T-421-1 Mr. Jeff Rieker Cambridge Homes 12228 NE 112th Place Kirkland, Washington 98033 - Subject: Preliminary Geotechnical Report Edmonds Avenue Site Edmonds Avenue NE and Sunset Boulevard NE Renton, Washington Dear Mr. Rieker: As requested,we have conducted a preliminary geotechnical engineering study for the subject project. The attached report presents our findings and recommendations for the geotechnical aspects of project design and construction. Our field exploration indicates the site is generally underlain by medium dense to dense sands with varying amounts of silt, and dense to very dense silty sand to sandy silt with varying amounts of gravel. We did not encounter groundwater seepage in any of our test pits. In our opinion, the site conditions encountered are suitable for the planned development. In general, the undisturbed native soils are suitable for supporting residential structures and pavements. We appreciate the opportunity to be of service during this phase of the project and look forward to working with you during the final design and construction phases. We trust the information presented in this report is sufficient for your current needs. If you have any questions or require additional information, please call. Sincerely yours, TERRA 4ASS,OCIATES, INC. Joh ( Sa"`fl r ` j.P.G\, Prb�ect En � g Geb'vg><st � Theoclocl�b'dh �.E. r .Lir�cip 1'Lri it 4, ,.Sj'1 RHO/ TomTouma, Touma Engineers and Land Surveyors 12525 Willows Road, Suite 101, Kirkland, Washington 98034 ,t 11_7^.-?7 9 1 ix: 0 "0 8 ) I --1 � ��t � tt,rli�ln�tf'rra-a�,Sf�r I.Iti� r� a TABLE OF CONTENTS P_ u� 1.0 Project Description...................................................................................................... 1 2.0 Scope of Work............................................................................................................ 1 3.0 Site Conditions............................................................................................................2 3.1 Surface...........................................................................................................2 3.2 Soils...............................................................................................................2 3.3 Groundwater..................................................................................................3 4.0 Geologic Hazards........................................................................................................3 4.1 Erosion...........................................................................................................3 4.2 Landslide........................................................................................................3 4.3 Seismic...........................................................................................................3 5.0 Discussion and Preliminary Recommendations.............................................................4 5.1 General ..........................................................................................................4 5.2 Site Preparation and Grading..........................................................................4 5.3 Excavations....................................................................................................5 5.4 Foundations....................................................................................................6 5.5 Basement and Retaining Walls........................................................................6 5.6 Slab-on-Grade Floors .....................................................................................7 5.7 Drainage ........................................................................................................7 5.8 Utilities .......................................................................................................... 8 5.9 Pavements...................................................................................................... 8 6.0 Additional Services .....................................................................................................8 7.0 Limitations..................................................................................................................9 Figures VicinityMap................................................................................................................... Figure 1 ExplorationLocation Plan............................................................................................... Figure 2 General Slope Fill Detail................................................................................................. Figure 3 Appendix, Field Exploration and Laboratory Testing...................................................................Appendix A (i) Preliminary Geotechnical Report Edmonds Avenue Site Edmonds Avenue NE and Sunset Boulevard NE Renton, Washington 1.0 PROJECT DESCRIPTION The proposed project is a 15-lot residential development. Detailed building and development plans are currently not available. A topographic site plan by Touma Engineers and Land Surveyors, dated December 1999, indicates several of the residences will be constructed with daylight basements. We expect the buildings will be wood-framed and will use conventional spread footing foundations. The site will be accessed from the east off Edmonds Avenue NE and from the north off NE 12th Street. Stormwater runoff will be collected by roadway catch basins and routed off-site near the southwestern corner of the property to an existing storm sewer along Sunset Boulevard NE. Site grading information is currently not available. However, the site plan provided to us indicates a four- to six- foot thick embankment fill will be constructed for the roadway leading into the site from Edmonds Avenue NE. Construction of the roadway off NE 12th Street will require raising grades along the western edge of the site by approximately two to eight feet. Cross sections on the site plan provided to us indicate cuts of eight to ten feet will be required for basement excavations in the eastern portion of the site. The sections show the slope between Edmonds Avenue NE and the residences terraced with several flat benches, or graded to a relatively flat yard area with an approximately eight-foot high retaining wall along the eastern edge of the property. The recommendations contained in the following sections of this report are preliminary and are based on information shown on the topographic site plan provided to us. We should review design drawings as they become available in order to supplement or amend our recommendations, as required. 2.0 SCOPE OF WORK On September 6, 2000, we excavated 5 test pits to depths ranging from 8 to 12 feet below existing surface grades. We also reviewed a geotechnical report prepared by Terra Associates, Inc. in February 1987. The subsurface investigation for the 1987 study included four test pits excavated in the southern portion of the current subject site. Using the information obtained from the current subsurface exploration and our previous study, we performed analyses to develop preliminary geotechnical recommendations for project design and construction. Specifically, this report addresses the following: • Soil and groundwater conditions • Geologic hazards • Site preparation and grading • Foundation design September 27, 2000 Project No. T-421-1 • Basement and retaining walls • Slab-on-grade floors • Drainage • Utilities • Pavements 3.0 SITE CONDITIONS 3.1 Surface The project site is an undeveloped, approximately two-acre parcel located west and adjacent to Edmonds Avenue NE, between Sunset Boulevard NE and NE 12th Street in Renton, Washington. The approximate location of the site is shown on Figure 1. The site is bordered by Edmonds Avenue NE to the east, NE 12th Street to the north, Sunset Boulevard NE to the south, and a PSE substation and undeveloped property to the west. In general, site topography slopes down to the west-southwest. Slope grades along the eastern margin of the site, adjacent to Edmonds Avenue NE, are generally steep to moderate with inclinations ranging from about 20 to 55 percent. Slope grades gradually flatten to the west- southwest with inclinations ranging between about 10 and 20 percent. Site elevations range from a high of approximately Elev. 320 near the northeastern corner of the site, to a low of about Elev. 272 near the southwestern corner of the site. The site is vegetated primarily with mature deciduous trees, some mature coniferous trees, and thick brush undergrowth. We observed several areas along the eastern margin of the site where fill had been dumped over the slope adjacent to Edmonds Avenue NE. Some of the fill appeared to be construction debris, including large slabs of asphalt. 3.2 Soils In general, the soils encountered in the test pits consist of native medium dense to dense sand to sand with silt and dense to very dense silty sand to sandy silt with varying amounts of gravel. The dense to very dense silty sand/sandy silt with gravel appears to be glacial till. We encountered glacial till or glacial till-like soils in five of the nine test pits. We encountered approximately two feet of fill, consisting of light brown silty sand with gravel, and some organic material in Test Pit TP-104. Test Pit TP-104 is located on the steep slope along the eastern edge of the site. As previously discussed, some of the fill contains construction debris, including slabs of asphalt. Detailed descriptions of the subsurface conditions encountered in the test pits are presented on the Test Pit Logs in Appendix A. The approximate test pit locations are shown on Figure 2. The Preliminary Geologic Map of Seattle and Vicinity, Washington, by H.H. Waldron and others (1962), classifies the soils in the vicinity of the site as recessional out«•ash sand overlying Vashon till, or Vashon till. The soils we observed in the test pits are generally consistent with these classifications. Page No. 2 September 27, 2000 Project No. T-421-1 3.3 Groundwater We did not observe groundwater seepage in any of the test pits. However, based on the soil conditions we observed, we expect a seasonal perched water table will develop above the dense to very dense glacial till and till- like soils during the wet winter and spring months. This will occur as surface water infiltrates through the upper relatively permeable sands and becomes perched on the underlying, relatively impermeable glacial till and glacial till-like soils. When combined with a positive gradient, the groundwater will tend to flow laterally along the till contact, emerging at lower elevations as seeps and springs. We did not observe any indications of obvious groundwater seepage or springs on the steeper slopes or at lower site elevations. 4.0 GEOLOGIC HAZARDS 4.1 Erosion The soils encountered at the site are classified as Indianola loamy fine sand, 4 to 15 percent slopes (InQ, and Ragnar-Indianola association, sloping (RdQ, by the Soil Conservation Service. The InC soils are shown in the northern portion of the site. The remainder of the site is mapped as RdC soils. The erosion hazard for InC soils and RdC soils are classified as slight to moderate and moderate, respectively. While we did not observe indications of significant active erosion at the site, the site soils will be susceptible to erosion when exposed. Therefore, erosion protection measures, as required by the City of Renton, should be in place prior to and during grading activities at the site. 4.2 Landslide Portions of the slope along the eastern margin of the site exceed 40 percent. We did not observe indications of obvious instability on any of the site slopes. The steep slopes along the eastern margin of the site appeared stable and generally supported growth of mature trees, including relatively straight coniferous trees. In our opinion, provided the recommendations contained in this report are followed, development of the site as proposed will not increase the potential for slope instability on-site or on adjacent properties, and the risk for such an occurrence would be minimal. 4.3 Seismic The Puget Sound area falls within Seismic Zone 3, as classified by the 1997 Uniform Building Code (UBQ. Based on the soil conditions observed and the local geology, a soil profile type of Sc, from Table 16-J of the 1997 UBC, should be used for design purposes. Liquefaction is a phenomenon where there is a reduction or complete loss of soil strength due to an increase in water pressure induced by vibrations. Based on the soil and groundwater conditions we observed, it is our opinion that the risk for liquefaction to occur at this site during an earthquake is minimal. Page No. 3 September 27, 2000 Project No. T-421-1 5.0 DISCUSSION AND PRELIMINARY RECOMMENDATIONS 5.1 General Based on our study, it is our opinion that the site is suitable for the proposed development. Buildings can be supported on conventional spread footings bearing on competent native soils below the topsoil and uncontrolled fill. If required, spread footings can also be supported on structural fill placed and compacted on the competent native soils. Floor slabs and pavements can be similarly supported. The planned roadway along the western edge of the site will require raising grades by approximately two to eight feet. Due to the proximity of the roadway to the western edge of the site, it appears that the downgradient edge of the road fill will have to be structurally retained. Retaining wall alternatives include a cantilevered reinforced concrete wall, a segmental-block wall with geogrid reinforcing, and a reinforced-earth wall. The preliminary drawing indicates the roadway retaining structure will be located approximately ten feet from the top of a rockery located on the adjacent property to the west. We recommend that we review final grading and development plans as they become available to develop geotechnical recommendations for design and construction of the retaining structure at this location, and to adequately assess potential stability impacts to the adjacent rockery. Portions of Lots 1 through 9, Lots 11 and 12, and Lot 15 are situated on the steep slope along the eastern margin of the site. Available topographic information indicates slope grades in this portion of the site range between approximately 20 and 55 percent. It should be noted that the City of Renton limits removal of trees on slopes of 40 percent and greater. The following recommendations should be incorporated into the project design drawings and construction specifications. These recommendations are preliminary,and may be altered or augmented upon review of the final plans. 5.2 Site Preparation and Grading To prepare the site for construction, all vegetation, organic surface soils, uncontrolled fill, and other deleterious materials should be stripped from the proposed building and pavement areas. Soils containing organic material will not be suitable for use as structural fill but may be used in non-structural areas or for landscaping purposes. The on-site soils generally appear suitable for use as structural fill. However, some of the soils contain a significant amount of fines (silt and clay size particles) and will be difficult to compact as structural fill when too wet. The ability to use the silty soils from site excavations as structural fill will depend on their moisture content and the prevailing weather conditions at the time of construction. Page No. 4 September 27, 2000 Project No. T-421-1 If the moisture content of the on-site soils cannot be maintained near their optimum percentage, or if grading activities must take place during the wet winter or spring months, the owner should be prepared to import wet weather structural fill. For this purpose, we recommend importing a granular soil that meets the following grading requirements: U.S. Sieve Size Percent Passing 6 inches 100 No. 4 75 maximum No. 200 5 maximum* *Based on the 3/4-inch fraction. Prior to use, Terra Associates, Inc. should examine and test all materials imported to site for use as structural fill. Structural fill should be placed on a horizontal subgrade of undisturbed native soil in uniform loose layers not exceeding 12 inches, then compacted to a minimum of 95 percent of the soil's maximum dry density as determined by ASTM Test Designation D-689 (Standard Proctor). The moisture content of the soil at the time of compaction should be within two percent of its optimum, as determined by this same standard. In non-structural areas or for backfill in utility trenches below a depth of 4 feet, the degree of compaction could be reduced to 90 percent. Embankment fill will be required for the proposed roadway that enters the site off Edmonds Avenue NE, and the proposed roadway along the western edge of the site. Embankment fills placed on slopes exceeding a grade of 20 percent must be keyed and benched into competent native soils. Subsurface drains may also be required. The need for subsurface drains should be evaluated in the field at the time of construction. A general slope fill detail is presented on Figure 3. All permanent cut and fill slopes should be graded with a finished inclination no greater than 2:1 (Horizontal:Vertical). Upon completion of grading, the slope face should be appropriately vegetated or provided with other physical means to guard against erosion. Final grades at the top of the slope must promote surface drainage away from the slope crest. 5.3 Excavations All excavations at the site associated with confined spaces, such as utility trenches, must be completed in accordance with local, state, or federal requirements. Based on current Occupational Safety and Health Administration (OSHA) regulations, the medium dense to dense sands and weathered glacial till soils would generally be classified as Group C soils. The very dense glacial till and glacial till-like soils would be classified as Group A soils. While our test pits did not encounter groundwater, seepage may be encountered in excavations extending to the till- like soils (encountered approximately 5 to 11 feet below the ground surface) during the wet winter and spring months. Accordingly, for adequately dewatered excavations more than 4 feet and less than 20 feet deep, the side slopes of the excavation should be laid back at a minimum slope inclination of 1.5:1 in Group C soils. Page No. 5 September 27, 2000 Project No. T-421-1 Temporary excavations into the very dense glacial till soils can be completed to an inclination of 0.75:1. If there is insufficient room to complete the excavations in this manner or if excavations greater than 20 feet deep are planned, temporary shoring may be necessary to support the excavations. Properly designed and installed trench boxes can be used to support utility trench excavations. This information is provided solely for the benefit of the owner and other design consultants, and should not be construed to imply that Terra Associates, Inc. assumes responsibility for job site safety. It is understood that job site safety is the sole responsibility of the project contractor. 5.4 Foundations Spread Footings The buildings may be supported on conventional spread foundations bearing on competent native soils or on structural fills placed above competent native soils, as recommended in Section 5.2 of this report. Perimeter foundations should be placed at least 18 inches below final exterior grades for frost protection. Interior foundations can be constructed at any convenient depth. We recommend designing foundations for a net allowable bearing capacity of 3,000 pounds per square foot (psf). For short-term loads, such as wind and seismic, a one-third increase in this allowable capacity can be used. For expected building loads, foundation settlements should be less than one-half inch. For designing foundations to resist lateral loads, a base friction coefficient of 0.4 can be used. Passive earth pressures acting on the sides of the footings and buried portions of the foundation stem walls can also be considered. We recommend calculating this lateral resistance using an equivalent fluid weight of 300 pounds per cubic foot (pcf). We recommend not including the upper 12 inches of soil in this computation because it can be affected by weather or disturbed by future grading activity. This value assumes the foundation will be constructed neat against competent native soil or backfilled with structural fill, as described in the Section 5.2 of this report. The passive value recommended includes a safety factor of 1.5. 5.5 Basement and Retaininz Walls The magnitude of earth pressures developing on basement or retaining walls will depend on the quality and compaction of the wall backfill. We recommend placing and compacting wall backfill as structural fill. Below improved areas, such as pavements or floor slabs, the backfill should be compacted to a minimum of 95 percent of its maximum dry unit weight, as determined by ASTM Test Designation D-698 (Standard Proctor). In unimproved areas, the relative compaction can be reduced to 90 percent. To prevent hydrostatic pressure development, wall drainage must also be installed. Drainage behind basement walls can be provided by attaching prefabricated wall drainage panels, such as Miradrain 6000, to the outer side of the wall, or by backfilling the wall with a clean granular material, such as pea gravel. A foundation drain consisting of a four-inch diameter perforated PVC pipe should be installed at the base of the wall for collection and removal of the intercepted groundwater. The foundation drain should be surrounded by at least six inches of pea gravel. All drains must drain to a controlled point of approved discharge. Cleanouts should be installed at appropriate and easily accessible locations along the drain alignments. These cleanouts should be serviced at least once each year. Page No. 6 September 27, 2000 Project No. T-421-1 With wall backfill placed and compacted as recommended and drainage properly installed, we recommend designing unrestrained walls for an active earth pressure equivalent to a fluid weighing 35 pcf. For restrained walls, an additional uniform lateral pressure of 100 psf should be added. These values assume a horizontal backfill condition and that no other surcharge loading, such as traffic, sloping embankments, or adjacent buildings, will act on the wall. If such conditions will exist, then the imposed loading must be included in the wall design. Friction at the base of foundations and passive earth pressure will provide resistance to these lateral loads. Values for these parameters are provided in Section 5.4 of this report. 5.6 Stab-on-Grade Floors- Slab-on-grade floors may be supported on subgrades prepared as recommended in the Section 5.2 of this report. Immediately below the floor slab, we recommend placing a four-inch thick capillary break layer of clean, free- draining sand or gravel having less than three percent passing the No. 200 sieve. This material will reduce the potential for upward capillary movement of water through the underlying soil and subsequent wetting of the floor slab. Where moisture by vapor transmission is undesirable, a durable plastic membrane should be placed over the capillary break material. The membrane should be covered with two inches of clean moist sand to guard against damage during construction and to aid in curing of the concrete. 5.7 Drainage Surface Final exterior grades should promote free and positive drainage away from the building areas. We recommend providing a gradient of at least three percent for a minimum distance of ten feet from the building perimeter, except in paved locations. In paved locations, a minimum gradient of one percent should be provided unless provisions are included for collection and disposal of surface water adjacent to the structure. Surface water must not be allowed to flow uncontrolled over the crest of site slopes and embankments. Surface water should be directed away from the slope crests to a point of collection and controlled discharge. If site grades do not allow for directing surface water away from the slopes, it should be collected and tightlined to the bottom of the slope in a controlled manner. Subsurface We recommend installing a continuous drain along the outside lower edge of the perimeter building foundations. The foundation drains and roof downspouts should be tightlined separately to an approved discharge facility. Subsurface drains must be laid with a gradient sufficient to promote positive flow to a controlled point of approved discharge. All drains should be provided with cleanouts at easily accessible locations. These cleanouts should be serviced at least once each year. Page No. 7 September 27, 2000 Project No. T-421-1 5.8 Utilities Utility pipes should be bedded and backfilled in accordance with American Public Works Association (APWA) or City of Renton specifications. As a minimum, trench backfill should be placed and compacted as structural fill as described in Section 5.2 of this report. If the soils excavated on-site are free of excessive deleterious material or debris and are not excessively moist, they should be suitable for use as backfill material. If construction takes place during winter or spring, it may be necessary to import structural fill for backfilling purposes. 5.9 Pavements Pavements should be constructed on subgrades prepared as described in Section 5.2 of this report. Regardless of the relative compaction achieved, the subgrade must be firm and relatively unyielding before paving. Proofrolling the subgrade with heavy construction equipment should be completed to verify this condition. The thicknesses of the various components of the pavement depend on the subgrade soils and the traffic conditions to which the pavement will be subjected. We expect traffic to mainly consist of light passenger vehicles with only occasional heavy service vehicles. Based on this information and a properly prepared and stable subgrade, we recommend the following pavement sections: • Two inches of asphalt concrete(AC)over four inches of crushed rock base (CRB) • Two inches of AC over three inches of asphalt-treated base (ATB) All paving materials should conform to the Washington State Department of Transportation (WSDOT) specifications for Class B asphalt concrete,ATB and CRB. Long-term pavement performance will depend on surface drainage. A poorly-drained pavement section will be subject to premature failure as a result of surface water infiltrating into the subgrade soils and reducing their supporting capability. To improve performance, we recommend surface drainage gradients of at least two percent. Some longitudinal and transverse cracking of the pavement surface should be expected over time. Regular maintenance should be planned to seal cracks when they occur. 6.0 ADDITIONAL SERVICES Terra Associates, Inc. should review the final design and specifications in order to verify that earthwork and foundation recommendations have been properly interpreted and incorporated into project design and construction. We should also provide geotechnical services during construction in order to observe compliance with the design concepts, specifications, and recommendations. This will also allow for design changes if subsurface conditions differ from those anticipated prior to the start of construction. Page No. 8 September 27, 2000 Project No. T-421-1 7.0 LIMITATIONS We prepared this report in accordance with generally accepted geotechnical engineering practices. This report is the property of Terra Associates, Inc. and is intended for specific application to the Edmonds Avenue Site project. This report is for the exclusive use of Cambridge Homes and their authorized representatives. No other warranty, expressed or implied, is made. The analyses and preliminary recommendations presented in this report are based upon data obtained from the on- site test pits. Variations in soil conditions can occur, the nature and extent of which may not become evident until construction. If variations appear evident, Terra Associates, Inc. should be requested to re-evaluate the recommendations in this report prior to proceeding with construction. 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M7P REFERENCE: THE THOMAS GUIDE, METROPOLITAN PUGET SOUND, PAGES 626 AND 656, 2000 EDITION. t VICINITY MAP TERRA EDMONDS AVENUE SITE ASSOCIATES RENTON, WASHINGTON Geotechnical Consultants Proj.No. 421-1 Date SEPT. 2000 Figure t STRUCTURAL FILL REVERSE SLOPE TO DRAIN B 1 TOE OF NEW SLOPE _ 1 2 2 �--6' -I 1 A B 1 1 EXISTING - SLOPE TO 2 1--6'--4 TYPICAL SLOPE BENCH 1 A (MAY REQUIRE SUBDRAIN IF SEEPAGE 1 CONDITIONS ARE INDICATED) \` TOE BENCH CUT AND DRAIN (SEE NOTE 1) 6' -I KEYWAY AND DRAIN (SEE NOTE 1) NOT TO SCALE NOTES: 1) DRAINS SHALL CONSIST OF 6" DIAMETER PERFORATED PVC PIPE ENVELOPED IN 1 cu. ft. OF WASHED 1" MINUS DRAINAGE GRAVEL. 2) — TOPSOIL REMOVAL THICKNESS BETWEEN KEYWAY AND BENCHES. © — VERTICAL ELEVATION DIFFERENCE BETWEEN TOP OF LOWER BENCH BACKCUT AND UPPER BENCH ELEVATION. GENERAL SLOPE FILL DETAIL P# TERRA EDMONDS AVENUE SITE ASSOCIATES RENTON, WASHINGTON Geotechnical Consultants Proj.No. 421-1 Dote SEPT. 20001Figure 3 APPENDIX A FIELD EXPLORATION AND LABORATORY TESTING Edmonds Avenue Site Renton,Washington On September 6, 2000, we performed our field exploration using a track-mounted hoe. We explored subsurface soil conditions at the site by excavating 5 test pits to a maximum depth of 12 feet below existing grades. We augmented our recent field investigation by reviewing the logs of four backhoe test pits excavated in the southern portion of the site by our firm in December 1986. The locations of our recent and previous test pits are shown on Figure 2. The test pit locations were approximately determined by measuring from existing site features and adjacent roadways and structures. The test pit logs are presented on Figures A-2 through A-6. An engineering geologist or engineer from our office maintained a log of each test pit as it was excavated, classified the soil conditions encountered, and obtained representative soil samples. All soil samples were visually classified in accordance with the Unified Soil Classification System. A copy of this classification is presented on Figure A-1. Representative soil samples obtained from the recent test pits were placed in sealed plastic bags and taken to our laboratory for further examination and testing. The moisture content of each sample was measured and is reported on the test pit logs. Grain size analyses were performed on six of the samples. The results are shown on Figures A-7 through A-9. Project No. T-421-1 I I MAJOR DIVISIONS LETTER TYPICAL DESCRIPTION SYMBOL I � Clean GW1--fines. Well-graded gravels, gravel-sand mixtures, little or no GRAVELS Gravels _ J m ' (less than GP Poorly-graded gravels, gravel-sand mixtures, little or O co N More than 5% fines) no fines. U) .� 50% of coarse Silty gravels, gravel-sand-silt mixtures, non-plastic cu fraction is Gravels GM fines. > larger than No. — - - W LD 4 sieve with fines Z �'� GC Clayey gravels, gravel-sand-clay mixtures, plastic fines. oCD Clean SW Well-graded sands, gravelly sands, little or no fines. 0 SANDS Sands W c Z (less than Poorly-graded sands or gravelly sands, little or no c More than 5% fines) SP fines. 50% of coarse a0 — fraction is- SM Silty sands, sand-silt mixtures, non-plastic fines. (3 0 smaller than Sands _ No. 4 sieve with fines SC Clayey sands, sand-clay mixtures, plastic fines. Inorganic silts, rock flour, clayey silts with slight U) Fu SILTS AND CLAYS ML plasticity. _j O Q)O O i�N CL Inorganic clays of low to medium plasticity, (lean clay). E o Liquid limit is less than 50% ---- 0 Z N OL Organic silts and organic clays of low plasticity. 0LO Z CD C: Q c:E > _ M H Inorganic silts, elastic. C � �' SILTS AND CLAYS S - -- ---- -- - O m CH Inorganic clays of high plasticity, fat clays. z 0 (n Liquid limit is greater than 50% LL OH Organic clays of high plasticity. HIGHLY ORGANIC SOILS PT Peat. DEFINITION OF TERMS AND SYMBOLS w Standard Penetration 2, OUTSIDE DIAMETER SPLIT Q Density Resistance in Blows/Foot SPOON SAMPLER o' (7 Very loose 0-4 2.4" INSIDE DIAMETER RING SAMPLER o Loose 4-10 OR SHELBY TUBE SAMPLER Medium dense 10-30 zz Dense 30-50 1 WATER LEVEL (DATE) Very dense >50 Tr TORVANE READINGS, tsf Standard Penetration Pp PENETROMETER READING, tsf gConsistency Resistance in Blows/Foot DID DRY DENSITY, pounds per cubic foot Very soft 0-2 LL LIQUID LIMIT, percent o Soft 2-4 Medium stiff 4-8 PI PLASTIC INDEX J Stiff 8-16 U) Very stiff 16-32 N STANDARD PENETRATION, blows per foot Hard >32 UNIFIED SOIL CLASSIFICATION SYSTEM TERRA EDMONDS AVENUE SITE ASSOCIATES RENTON, WASHINGTON Geotechnical Consultants Proj. No. T-421-1 Date SEPT 2000 Figure A-1 ---------- DPIONDS14 VENLIE Nc SS �u �,y —__--__—_—_—�'--_-~—_----- ----=_-- I , 1 �a 1 31 S TP-104 I T I TP-�I03 " 3'a TP-I01 t i j i I TP-105 S 1 12 j �� 3 9 I f O 318 I j -4 5 j 6 8 ------- --I I 15� /J 1 394 TP-1' ,. 2 -- --- ------------- - �o 10 i I ( TP-6 2 E 14 I {r4 272 _ 3 � 1 1 TP-102 1 278� ti -------- -- - ®TP-2 APPROXIMATE SCALE 50 0 50 100 feet LEGEND: APPROXIMATE CURRENT TEST PIT LOCATION (09-06-00) ® APPROXIMATE PREVIOUS TEST PIT LOCATION (12-17-86) REFERENCE: SITE PLAN PREPARED BY TOUMA ENGINEERS & LAND SURVEYORS, JOB No. 7910, SHEET 1 OF 1, DATED DECEMBER, 1999. EXPLORATION LOCATION PLAN g® TERRA EDMONDS AVENUE SITE ASSOCIATES RENTON, WASHINGTON r'.otechnical Consultants Proj.No. 421-1 Date SEPT. 2000 Figure 2 Test Pit No. TP-101 Logged by- JCS Approximate Elev. 310 Date- 9/6/00 Depth Moisture (ft.) Soil Description Content (%) 0- - 12 inches duff and topsoil. Light tan to light gray SAND to SAND with silt, fine grained, medium dense, dry. With occasional fine gravel. (SP/SP-SM). Root to 3 approximately 3 feet. 5 Mottled gray to gray SAND to SAND with silt, fine grained, medium 10 dense to dense, moist. With occasional fine gravel. (SP/SP-SM) 17 Increasing silt and gravel below 11 feet. 17 Test pit terminated at 12 feet. No groundwater seepage. 15 Test Pit No. TP-102 Logged by- JCS Approximate Elev. 286 Date- 9/6/00 Depth Moisture (ft..) Soil Description Content 0- - 12 inches duff and topsoil. Light tan to light gray SAND to SAND with silt, fine grained, medium dense, dry. With occasional fine gravel. (SP/SP-SM) Roots to approximately 2 feet. 5 Test pit terminated at 8 feet. 1 Q No groundwater seepage. 15 TEST PIT LOGS TERRA EDMONDS AVENUE SITE RENTON, WASHINGTON ASSOCIATES Geotechnical Consultants Proj. No. T-421-1 Date SEPT 2000 Figure A-2 Test Pit No. TP-103 Logged by: JCS Approximate Elev. 312 Date: 9/6/00 Depth Moisture ent nt (ft.) Soil Description Co(nt 6inchesduff and topsoil. Light brown silty SAND,fine grained,medium dense,dry. Withoccasional �finegravel. (SM) Fine roots to approximately12inches. 9 Mottled gray silty SAND with gravel,fine sand,fine gravel,dense to very 5 dense,moist. (SM) (Glacialtill) 10 Test pit terminated at 8feet. 10 No groundwater seepage. 15 Test Pit No. TP-104 Logged by: JCS Approximate Elev. 304 Date: 9/6/00 Depth Moisture ent nt (ft.) Soil Description Co(nt FILL:light brown silty sand with gravel,fine grained,dry. Withorganic material and roots. Mottled gray silty SAND with gravel to sandy SI LTwith gravel,fine sand, fine to coarse gravel,medium dense to dense,,moistto wet. (SM/ML) (Weathered glacial till) 5 1.5-foot diameter boulder at approximately 6 feet. 16 Blue-gray silty SAND with gravel,fine sand,fine to coarse gravel,dense, 10 moisttowet. (SM) (Glacial till-like) 14 Test pitterminated 10feet. No groundwater seepage. 15 TEST PIT LOGS TERRA EDMONDS AVENUE SITE ASSOCIATES RENTON, WASHINGTON Geotechnical Consultants Proj. No. T-421-1 ]-Date SEPT 2000 Figure A-3 J Test Pit No. TP-1 05 Logged by: JCS Approximate Elev. 289 Date: 9/6/00 Depth Moisture ent nt (ft.) Soil Description Co(nt 0 18 inches duff and topsoil. Mottled gray-brown SAND with silt,fine grained,dense,dry to moist. (SP-SM) With occasional fine gravel. 4 5 Gray-brown silty SAND with gravel,fine sand,fineto coarse gravel,dense 12 toverydense,moist. (SM) (Glacialtill) 10 Test pit terminated at9feet. No groundwater seepage. 15 TEST PIT LOGS TERRA EDMONDS AVENUE SITE ASSOCIATES RENTON, WASHINGTON Geotechnical Consultants Proj. No. T-421-1 Date SEPT 2000 Figure A-4 Test Pit No. TP-1 Logged by: MM Approximate Elev. 287 Date: 12/17/86 Moisture Depth i (ft.) Soil Description Content 6 inches topsoil, Reddish-brown silty SAND,loose,moist. (SM) With numerous roots. Gray-brown SAND,medium dense,dry to moist. (SP) Increasing moisture 5 5 and density with depth. 10 14 15 Test pitterminatedat14feet. No groundwater seepage. 20 Test Pit No. TP-2 Logged by: MM Approximate Elev. 282 Date: 12/17/86 Depth Moisture P Content (ft.) Soil Description 12 inches topsoil. Reddish-brown silty SAND,loose,moist. (SM) With numerous fine roots. 5 Tan sandy Sl LT/CLAY,stiff,moist to wet. (ML/CL) 31 Gray-brown SAND,fine to medium grained,medium dense to dense,dry to moist. (SP) 10 6 15 Test pit terminated at14feet. No groundwater seepage. 20 TEST PIT LOGS TERRA EDMONDS AVENUE SITE ` ASSOCIATES RENTON, WASHINGTON - - - Geotechnical Consultants Proj. No. T-421-1 Date SEPT 2000 Figure A-5 Test Pit No. TP-6 Logged by- MM Approximate Elev. 276 Date- 12/17/86 Moisture Depth (ft.) Soil Description Content 6 inches topsoil. Dark brown silty SAND,loose,moist. (SM) With numerous roots. Gray SAND,fine to medium grained,medium dense to dense,dry to moist. 5 (SP) -10 Gray silty SANDwith gravel,very dense,moist,with occasional cobbles. 13 (SM) (Glacialtill) 13 15 Test pitterminated at 14 feet. No groundwater seepage. 20 Test Pit No. TP-7 Logged by- MM Approximate Elev. 278 Date- 12/17/86 Depth Moisture (ft) Soil Description Content 10 inches topsoil. Brown silty SAND,loose,moist. (SM) With numerous fine roots. 20 Mottled gray-tan sandy Sl LT/CLAY,soft,moist. (MUCL) 18 5 Gray silty SAND with gravel,very dense,moist. (SM) (Glacial till) With occasional cobbles. 10 14 Test pitterminated at 10.5feet. No groundwater seepage. 15 20 TEST PIT LOGS TERRA EDMONDS AVENUE SITE ASSOCIATES RENTON, WASHINGTON Geotechnical Consultants Proj. No. T-421-1 Date SEPT 20001 Figure A-6 SIEVE ANALYSIS HYDROMETER ANALYSIS SIZE OF OPENING IN INCHES NUMBER OF MESH PER INCH, US STANDARD GRAIN SIZE IN MM Q) O 0 0 O O O O O O 0 0 O O N CN N N? {.+.00 N OJ ? J+. O O O O O O O ? (.N N CO O ? CN N 1'. 100 0 � ;.. 901 1 10 cD 0 80 20 0 M � o -7-1 c� O x n 70 30 m o D Fri c � � o D 60 40 C7 50 50 Cn m O < 40 60 M v m ZE O 30 70 m N 20 80 m 7D c� z �) 10 90 o (z) Z Cn (/) 0 100 III m EDN o 0 00 0 0 0 0 o°D O7 �' �' � 00 mp i4 iv � � o 0 0 0 00 0 0 0 0 0 fTl o 0 0 0 0 0 A Iv �m GRAIN SIZE IN MILLIMETERS Z Z COARSE FINE COARSE MEDIUM FINE o m D COBBLES GRAVEL AN FINES Test m Pit Depth Moisture Key p USCS Description LL PL ft.Number ( ) Content • TP-101 3.0 SP SAND 0 TP-101 10.0 SP—SM SAND with silt SIEVE ANALYSIS HYDROMETER ANALYSIS SIZE OF OPENING IN INCHES NUMBER OF MESH PER INCH, US STANDARD GRAIN SIZE IN MM C,C" u rQ A rn O C> O O O O O O O O O O N ? C.+ N N ?OD N CO .P A O C) CD CD C:) CZ)a, ? CA N Ca CD3.. C. N -- 100 0 i 90 �.. 10 c� 0 D 80 20 g X M c� O X � 70 30 M 73 Friz 73 Ln n D z —, D —' 60 0 40 n rt � O W z 50 50 m 40 60 CC rm o 30 70 m o � � N [I i I I-20 Nil 80 i m Z D 10 90 o �c)ZZ C) (T1 N O O 0 0 0 CD O CD O O N O W N O O O O O O O CD CD CDp Cn m Fri GRAIN SIZE IN MILLIMETERSr'j c) c) oCD 10 n' =z Z COARSE FINE COARSE MEDIUM FINE o =m D COBBLES Av AN FINES o m Key Test Pit Depth USCS Description Moisture LL PL Number (ft.) Content (%) n • TP-101 12.0 SP—SM SAND with silt CO O TP-103 8.0 SM silty SAND SIEVE ANALYSIS HYDROMETER ANALYSIS SIZE OF OPENING IN INCHES NUMBER OF MESH PER INCH, US STANDARD GRAIN SIZE IN MM _ w Cn - w \\ \\\\ \ N A O) O O O O O O CD CD O CD O O O N ? w N N? 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