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Home My WebLink About03158 - Technical Information Report - Drainage i , � � � � � v ... 7 "v i � D�C 0 Q 2003 r..., � �. �... ;�'..,. . � _.-.�l10E ..�._........�.. m�.�.��._�,�..��. �'��3�2M pRA T,A�G� �P4�2'�' < �"C3k2 �S S�C��2�` 3��' ; 27�C3 �� !'��$� :��'��T , : ��'x'��I, �l',A�H��I�� '' < ; STORM DRAINGE REPORT LUA-03-051 , SHPL-A OFFICE FILE NO. 820-001-031 PREPARED BY I TOUMA ENGINEERS I 6632 SOUTH 191ST PLACE , SUITE E-102 KENT, WA. 98032 ', (425) 251-0665 '� December 1 , 2003 �� ' � � , ,�,��' d ra�' ,�,� '��v� , '� � `�.�;� .�. �,� .� i"� 4 h., � � O�� .. �� .•�1� s� � �"� ��{� �`�-�"��, � i FG��TE�ti�3�('�+,�� +-4.�C'� ;,t�.' - 1 C.}��'��"�°iJ uj;rli'�Cj.._..� ,...i „�..�.��,�,,,,,,,., __.. _..a ��'�C� �C--�-� � I �� i _ � ' King County Department of Development and.Environmental Services TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND Part 2 PROJECT LOCATION AND PROJECT ENGINEER � DESCRIPTION Pro'ect Owne� � Pro'ect Name G�rry' �u/�-�Gv� � �K�' S'hr.�� P/�� Address n O•�Q�, 2Ti�,� � ,��i� Location 2 3 ! Township Phone /�- s E 72S=2z�-�.�Z � Range Project Engineer •••••••••••••Section � io� �v/!'l4 Company ioU/�T ��/r/�I�e/`S Address/Phone �zS/-� Part 3 TYPE OF PERMIT Part,4 OTHER REVIEWS AND PERMITS APPLICATION Subdivison DFW HPA Shoreline Management Short Subdivisio COE 404 Rockery Grading DOE Dam Safety Structural Vaults Commercial FEMA Floodplain Other �� Other COE Wetlands ' Part 5 S1TE COMMUNITY AND DRAINAGEBASIN Community �' ��1� ��',�►�.��,�s�ti Drainage Basin ,� �� Part s SITE GHARACTERISTICS River Floodplain Wetlands Stream ��ps/Springs Critical Stream Reach � / High Groundwater Table Depressions/Swales Groundwater Recharge Lake � Other Steep Slopes ,� - 2- � Part 7 SO1LS . Soil Type Slopes Erosion Potential Erosive Velcoties -.�r1�Q/I��t /,�' � /�a�.� � ��D c�J Additional Sheets Attached Part 8 DEVELOPMENT LIMITATIONS REFERENCE LIMITATION/SITE CONSTRAINT Ch. 4—Downstream Anal sis �e� � ��bCJ/��'_si[!�ea�� Additional Sheets Attached Part 9:ESC REGZUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION AFTER CONSTRUCTION ,i Sedimentation Facilities JStabilize Exposed Surface �Stabilized Construction Entrance �iemove and Restore Temporary ESC Facilities ✓Perimeter Runoff Control Clean and Remove All Silt and Debris Clearing and Graing Restrictions ,/Ensure Operation of Permanent Facilities Cover Practices Flag Limits of SAO and open space ./Construction Sequence preservation areas Other Other 3 - I � Part 10 SURFACE WATER SYSTEM f � --_ � Method of Analysis Grass Lined Tank Infiltratio� ; Channel Vault Depression M Pipe System Compensation/Mitigati � Energy Dissapator Flow Dispersal on of Eliminated Site � Open Channel Stora e Wetland Waiver 9 � Dry Pond Stream Regional ± • Wet Pond Detention � Brief Description of System Operation � Facility Related Site Limitations I Reference Facility Limitation � . I 1 Part 11 STRUCTURAL ANALYSIS Part 12 EASEMENTSlTRACTS Cast in Place Vault ✓Drainage Easement Retaining Wall ��v�r�� ''�Access Easement Rockery> 4' High Native Growth Protection Easement Structural on Steep Slope Tract Other . Other Part 13 SIGNATURE OF PROFESSIONAL ENGINEER 1 or a civil engineer under my supervision my supervision have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attachments. To the best of my knowledge the information provided here is accurate. �-- -------� �% �I�u..� �` �� /� � /� 3 \ Si ned/Date _� _. � . TABLE OF CONTENTS I . PROJECT OVERVIEW II . CONDITIONS & REQUIRMENT SUSNIl�II�.RY III . OFF-SITE ANALYSIS IV. FLOW CONTROL AND WATER QUALITY V. CONVEYANCE SYSTEM ANALYSIS VI . SPECIAL REPORT AND STUDIES VII . SASIN AND OTHER CONIIr1UNITY AREAS VIII . OTHER PERMITS IX. EROSION/SEDMINTATION CONTROL DESIGN X. BOND QUANITIES WORKSHEET XI . MAITENANCE AND OPERATION MANUAL _ � . I. PROJECT OVERVIEW This project involves a single parcel of approximately 0.64 acres. The project is situated in the northeast end of the City of Renton. It is located within northwest quarter of Section 4, Township 23 North, Range 5 East W. M. The proposal is to create 4 lots, "Fill in" subdivision. Access to the proposed project will �,e frorn existing street, NE 21 st Street. The existing house and garage will remained on Lo�. 1. The site is bounded on the east and north by similar single family residence. It i� bounded on the south by NE 215� Street. NE 22"d Street right of way terminates at t. ,e west boundary of this property. The soils on the site are composed of Indianola (InC) gravelty and fine sand per th � King County Soil Survey. The Indianola series is made up of somewhat excessive drained soils that formed under conifers in sandy, recession and stratified glacial drift. This type of soil is designated by King County as Typ A oil and is good for infiltration system. The site is flat around proposed lot 1. The remaining topography of the site slopes from east to northwest direction at an average slope of 16 percent, except for a narrow band of steep slope obviously created by filling when the house was built. There is no indication of slope instability visible at the time of visiting t!�e site. The land at the bottom of the steep slope is relatively level to the west property line. The flow from the site is oriented from east to northwest directing sheet flows to NE 22"" Street and NE 23'd Street situate west of the site. Refer to downstream analysis for additional information. The proposed development of the property is considered as "infill" project and it is located in a Single Family (SF) zone. The City of Renton designates the site with t ie SF zoning. The SF zoning allows for a minimum lot size of 4500 square feet and � maximum density of 8 units per acre. The setbacks allowed in the SF zone are as follows: front yard setbacks, 20 feet; rear yard setbacks, 20 feet, and side yards i setbacks, 5 feet on alt interior lots, and 10 feet on comer lots. The City of Renton � Comprehensive Plan designates the site as Single-Family Residence, which is � consistent with present zoning. _ � f PROJECT REVIEW (Continued) -fhe density for the developed portion calculates at 6.43 dwelling unit per net c�ieveloped acre. There will be right of way dedication adjacent to NE 215t Street. Twelve feet of roadway dedication is along the south boundary of the site for NE :?15` street widening. Grading is very limited to construction of private road serving lots 2 through 4. The quantity of excavation for the private road and roadway irnprovements on adjacent street is estimated at 340 cu. Yd. Of course additional grading will be required when the new homes are built. rhere are trees scattered over the site pa�ticularly in the area of the proposed lot 4 and proposed private road. Trees along the west property line will �emain. Some tha evergreen trees along the boundary line between proposed lots 3 and 4 will remain that are outside the building envelope. - �- f_ . . i, I :i'� : C ..� i 961�1',I .� � �l\ ( I' , �, L. J�/ � � �'/, - ^,Sk flblll tif B/IN r ��1!1 yi .`�( �r� U ) �� '{j - x ,v� !�. J �`�. �)� ��SI t SE �� _��`.� -ci�.7��_,� � .: Z �-_ �� 1160(1 .'i' -i� ot �.B,9 'F ( + W � .�h;Ss S B91N SI '��'i1�IN� SEy N �;�� l. � PAF *�, 1 - �'1',! 4 - . 9U1H 51 �M f o ,�,p�t� \ v, m . ��`t:Y,� i-...T -- SF gl5f, 5! J ��, ,n \�^ � _ I �'.`.� �'S1 ...._ . . -- �� 12200 � � 5 vts �^ SE � y��1"�� 92NU SI ,��I � '" - i f..'',R'��>�> � `,, � h — - — — -- — - � '.t. 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S f (� N M /� N l l n 1. _ — - - - - - - -- -- ------ - _ 1'A(31,1?3.5.21t SCS 11't?S'I'I;IiN �VASl1ING'I'ON RUNOI�E�CURVG NUMl3E:ItS SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS (Publisfieci by SCS in 1982) RunoH curve numbers lor selected agricultural, suburt�n and urban land use (or Type tA rain►all distrit�ution, 24-hour storm duration. CURVE NUMBFRS BY I1YbROLOGIC SOIL GROUP LAND USE DESCRIP710N A fi C D -----------------___ ----------- ------ __-----___ ------— Cultivated lancl(1): winter condition 86 g1 94 95 Mountain open areas low growing brush and grasslands 74 82 89 92 Meadow or pasture t 65� 78 85 89 Wocxi or forest larxi: undisturbed or older second growth �2 64 76 et Wood or lorest 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 6E3 80 86 90 (air condition: grass cover on 50°�6 to 75°k of the area 77� 65 90 92 Gravel roads and parking lots (T6) 85 89 91 Dirt roads and parking lots 7'?_ 82 87 89 Impervious suriaces, pavement, roois, etc. r98� 98 98 98 --- - - Open water bodies: lakes, wetlands, ponds, etc. i00 100 100 100 ---- - — ---- --- - --------- - Single Family Residential (2) Dwelling Unil/Gross Acre °�6 Impervious (3) 1.0 dU/GA 15 Se��rale r.urve number 1.5 DU/GA 20 shall he seledeci 2.0 DU/GA 25 Icrr pervious and 2.5 DU/GA 30 irnpervious portion 3.0 DU/GA 34 ot the sile or basin I 3.5 DU/GA 38 4.0 DU/GA 42 I 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, °�6 impervious condominiums, apanments, 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 nun,bers. c'�} 3.5.2-3 I tl92 �K� I . I< I N c; c' �) ll N '1 1 . ��' � � II I N c� 'I� O N. S U IZ I� A (' f�. �V � "i� I�. R I� I�, S I (� N �1 A N ll n I. (2) CN values can I)P, BfP.� weiyhted WI1P.f1 they apply to pervious areas of sirnilar CN's (witt�in 20 CN pointsl. 1 lowever, hiyh CN areas should not be cornt�ined with low CN areas (unle�s the low CN areas are less than 15% of the subbasin). In this case, separate hydrographs �hould be generated and surnmed to form one hydrograph. - - _ . ----- ---- -- - -- - - - - --- - ----- I�IGUR1;:�.5.2A tll'UliOLO(:IC S<)IL GROUP OI%'I'IIE 5UII,S IN KING CUUN7'Y HYDROLOGIC HYDROLOGI: SOIL GFiOUP GROUP• SOIL GROUP GROUP` -- ---- _ . __. -- — /1lderwoocl C Orcas Peat D Arents, llldeiwocxl M�lerial C Oridia D Arents, Everett Material B Ovall C Beausitc C Pilchuck C Bellingharn D Puget D Briscot D Puyallup B Buckley D Ragnar B Coastal8eacf�es Variable Renton D Ea�lmont Silt Loam D Rive►wash Variable Edgewick C Salal C Everett A/B `Sarnmamish D Indianola ,�. Seattle D Kits�p C Shacar D Klaus C Si Silt C Mixed l�lluvial Land Variable Snohomish D Neilton A Sultan C Newbe�g B Tukwila D Nooksack C Urban Variable Normal Sandy Loarn D Woodinville O -- -_ - --- ---- —------- --------- - I HYDROLOGIC SOIL GROUP CLASSIFICATIONS � A. (Low runoff polential). Soils having high infiltration rales, eve�when Ihoroughly weUecl, and consislinq � chielly ot deep, well-to-excessively dralned sands or gravels. These solls f�ave a liigli rate o(water tra�smission. B. (Moderately low runoH potential). Soils having moderate infiltration rates wfien tt�orougt�ly wetted, and consisting chiefly of moderately line to moderately coarse textures. Tf�ese soils have a rnoderate rate c�t water transmission. C. (Moderately high runoff potentiai), Soils having slow l�filtration rales when tfiorouglily wetted, ar�d consisling chie(ly of soils wkh a layer that impedes downward movement of water, or soils with moderately fine to(ine textures. These soils have a slow rate o(water t�ansmission. D. (High runol( potential). Soils having very slow in(iltration rates when thoroughly weUecl and consisling chiefly o(clay soils with a high swelling potential, soils witli a permanenl high water lable, soils whh a hardpan or clay layer at or near the surface, and shallow soils over nearly Im�rvious material. These oils I�ave a very slow rate of water transmission. ' From SCS, TR-55, Second Edition, June 1986. Exhibit A-1. F�evisions made trom SCS, Soil Interpretali� n Record, Form �YS, Se��tember 1988. <,�> 3.5.7_-2 I IlQ, ��<ti1 • KING C: OUNTY, WASiIINC; TON, SURrACE WATBR DPSI (3N MANUA �, _ _ _ --- -- -- -- - - - - _ _._ _--- - - - --- -- - - -- TABLF 3.S.lC "e" AND "k" VALUF.S USED IN 7'IME CALCULA'tIONS FOR HYDR(K;RAPHS ' �� - ---- -- - --- - -- - - ------ — - �--- --- ---- -----..___ ------ -_—--- 'n;Shect ftow F�uaibn!.tarr*�q'e Vnlues(for Ihe hhtnl;fOp h c�f Ira•�el) n,• Sn�ooth eurlacea(co�c�e�e.aK�iww�i.ve�ei.ix�e�a:.�,d�.:.�:�ad s:.1) l.n�� Fnnow f��l.]s n I.�ose�on�urlar_s(i�0 rlS�dlM) 0 05 Ci�lk•atM so�wdh rpcyue Carer(�<-0?0 h/h) 008 GAu+ni�rf So0 wilh resklue cwer(S>0?0�/fl) 0.17 $tqA{a.'irir�ra,•,s end lav+ns 0.15 Oe�se p�asses o.2� Bermuda q�.,es Q�1 qanpe(nrlursl) 0 13 Y✓a�ds or(aesl whh t1pM w.�erbrush 0�0 Wpode p fo��•s�wRh denu u�rle�bush �AO - ---- - - ._----------------- - -------- --- -- - - -- -- -- 'Manr'aq"�lues�ix sheet flow only.Irpn pu�lpn erd M�xlows 1976{Saa TR-S5.1066) 'Y'Vr�ves Usad M Traval Tlms/Tims d Ca�cenuetlon CA�tt�albns SF�Pow Co�entraled Flow (Nter IM lnitlal J00 R.d sAeet Ilow,R -0.1) k� 1. fo�est whh!oeavy prourd I�qsr and rt�a:r�wf(n-0 10)------�- �----� - - - �--. _ . ' 9 2. 9nlshy p�,xtnd wMh t��e trpM(n �0 460) S 9. Fsrc�w or ml.�IrniRn tP�;1n.cJllvation(n>00401 8 �. f+�yh y�;�ss(n. 0 035) 9 5. Short yrru,pesture eM la+ms(n-0 OJO) t f � � Nn1�fy haro ypU.�(n�0.025) 1J I 7. f:ved eM prew9t e�eas(n-0.012) 27 I �._ -- -� -- ---------- — --------- — ----- ---- ..__ _ ___— I Cl�n�wl Flow(I�we�mn�ent)(At the Dcphmhq of..�;Fli�clannels R-02) k, � . . . ...---- . . . _ . _ _. ..----. . . __ .. - - 1. faes�xd swale wNh heavy p�ourd I��m(n - O 10) S 'j. FMf•Sf�!A(I1;1i�41(�p C(>tN5l�ITVM�p WI1�1(tQIIIIP[I CI17r�I18I(��l�•O QSQ) �0 ' � Rxk tirwd watcrway(n=0095) t5 1 ,�assaAwalerway(n-OOJO) » 5 Earth i{nod wa�ervay(n-00?S) p 6. CMP ptpe(n.002a) z� 7. Conuele pipe(0012) l2 9 O�her wa�c.waya and NPea �576/n GannN ilow(G��ttm�ovs strw�m,H - C.�� k� 9. lAe��ci��lru�Sirgam wph y �e�+✓,Jt(n- 00�0) pp 10 Rc��.fr�ed sUPam(n-O.OJ5) ?� ll. Gra:511ned cire:�m(n-OOJ0) 27 12. pth�r SOeams.nv'�n mt�de�'.��..�.•• :nj�pB ��,-��.. ••S�+e ChaWx 5.Table 5 3.6C!a edd;Yti,af�;anntr�y'n'v��s la c��rn clanne�s 3.5.2-7 i P� , KINC7 COUNTY, WASF{ INdTON, SURFACE W ATER DESIGN M A NUAL - ----_ ---- -------- — ---_- -- - - -- ---- --- FIGURE 3.S.1C 2-YFAR 24-IIOUR ISOPLUVIALS < --- '�.� � �� - � +- `P ��, - ' �- - -- \�1 - ., t��_ �r_—� � � ,. y; �`¢•.'r"' �,� -< -�, �� '� � > � � s, •`�- F "e � �� - 1 -- � �' r. -�_. ^� - I,�.� F r� ' --_ ;,�._. -- ., -,_ r r,� _ �.� - ,; ��,.:; � �.� ,� .. �\ . �� r.x� -%, _ - _ `Y r� .� _ _ �� - � 1�� `f �-. � - - _ � � =�,� 2. -- � ---_� ' ' _ ��``�� _ �- ," ..._ � � �,,. ; \� r,. .�E .r. — ll �� ,` , � / i ,. '� "�� -r j/ �� — 11�a ') .n `w1t�� ... � - � J { � � �� ./ / I � �'' � � S +e.? . �� ... - / �. _ ,.( ,hu S � � `` t' --� '��J - � � - - - �_.� � � ,'/� ` j � �-' ,.� = r r� � � �� ; _ � ' > � -- ' )� � I i _ `,_� � -• ` 1> _ �l .�.��. ( _ � •,-� -� � , "�'" r�'- ._� -� - � tl� `' i '�.—` _ � �� _�, r� (.�� S �--s j y + - ,. � � --+ - �� -- f� )� � : �-_ o. `, � - - � �� — - • ..� I � � � � �s_ � ' � "_�r.r.,�l ' �� '�I a '',j _ �X'" S�- — � � — — -- — ��`� t. i � �� \ `\i--- l� .i�� a�� i"� — -�� --� ._� � � � / �� . i -*�_=— — � � . ;�� {`'f i.. _ � - ._� -f--; . 1�� _ �. � .,._ �j � � �f � � :��a � ' - �� ` - ,�_„ �, ' N _ .� ?{L-` f= — - � . Y'1 � � �h r t,M Z v � ;f' x� •� —..µ..�` _ 'J � ' _� _ J �`-. � � � �y L _,� d.. ( � � / .. i � = � �, ' r +� r r e / � � � � `r . I , `��_ �,. ._� �f i, ^ � 2,a �� .�- - - - - - �� ;� -Y _�- !lf Nt� - � ...-� .�. 2-YEAR 24-HOUR PRECIPITATION `�� '. - • �`••-. ,.3A'�' ISOPLUVIALS OF 2-YEAR 24-HOUR � �� y --- - � 3. TOTAL PRECIPITATION IN INCHES • ' �• f ��' ti �.� - - �.� �. --- 0 1 2 3 4 S 6 7 S Mll�s � ~ / ' �lr N �Cr-. � �� . �� ,��' i:300.000 3.5.1-8 � �-�� . 1/'90 II. PRELIMINARY CONDITIONS SUMMARY CORE REQUIREMENTS 1-5 CORE REQUIREMENT#1: DISCHARGE AT NATURAL LOCATION The allowable outflows from the site will be discharged to its natural locations. CORE REQUIREMENT #2: OFF-SITE ANALYSIS A level one downstream analysis is a portion of this report. See the analysis later �� this report below. R L CORE REQUIREMENT #3. RUNOFF CONT O The increased peak runoff, due to any change in pervious conditions and increase of impervious areas, will be attenuated using peak rate runoff control in accordance with KCSWM, 1990 Edition. Initial calculation indicates there will be no detention , facility required. In order to reduce runoff from the site, we propose to include sing�e family infiltration system to re-charge the water back into the ground, and reduce t'ie flow from the proposed dispersion trench. Please refer to attached calculation. CORE REQUIREMENT#4: CONVEYANCE SYSTEM Conveyance system is minimal for this proposed short plat. Storm runoff from pri�� te road and new homes will be directed into infiltration systems proposed for this development CORE REQUIREMENT#5: EROSION/SEDIMENTATION CONTROL PLAN The erosion control plan will be designed using the King County storm manual. A series of sediment t�aps are anticipated at various locations. These will be situatf � and constructed to minimize any impact to downstream or offsite areas. - � Iil. OFF-SITE ANALYSIS This proposed short plat does not have appreciable off-site runoff entering the site NE 21 S' Street intercepts most of the runoff from the southeast and direct the flow south. B: DOWNSTREAM ANALYSIS The surface drainage from the site is directed to individual infiltration system �� recharging the ground with ar�ate flows. /��-�' �i L� �'�' � Natural flow of �sit� is directed from east to northwest toward NE 2?"d �treet anu Ne 23`d Stree stdrm systems. There exists underground conveyance pipe within t these two roads dir cting the flow west toward another existing storm system on Edmonds Avenue,�E"approximately 1100 feet west of the site. There is no indicatic�n of any flooding c�b�rnstream of the site. , P �t _ � IV FLOW CONTROL AND WATER QUALITY The following calculations conclude that the 100-year peak flow difference between the pre-developed flow and post-developed flow is less than 0.5 cfs. In accordance with 1990 KCSWDM, detention is not required. The following calculations include; Basin areas Time of Concentration Isopulvial graphs: 2, 10 and 100 year storms Pre-developed and Post developed hydrographs The soil type found on this site is classified as Indianola (InC) and is good t �� infiltration system. We therefore recommend installation of single family I infiltration system for the three new homes to be built on Lots 2 throuc: � inclusive. In discussing this matter with the owner, we ascertained that the size of homes proposed on the vacant lots will average about 2000 square feet on both stories. The surface area of each house will be sized at 1000 square feet, and the roof infiltration system will be designed to accommodate a 1000- foot home. Based on Section 4.1.1-3 of 1990 KCSWDM, the size of the trench is 25 fe��t long per 1000 square feet of roof for the Seatac regional area (See Figure 4.5.1 B below). -(� TIME OF CONC;ENTRATION - EXISTING CONDITION - FOR 2-YEAR. 24-HOUR STORM DESI( N SHEET FLOW- OFFSITE MANNING-i� 0 15 OVERLAND-L 220.00 FEE1 PRECIPITATION-P 2.00 INCIi SLOPE - S 0 13 F 1 IF 1 1 11 01 MINI I f FS � IMF� Of- C(��NCE- f f?A� I I�,�N DEVEI.OPED CONDITIO�J Sf IEF 1 f=1_(�W �?FFSI TF MANNING-n 0.�'% OVERLAND-L 80.00 FEE � PRECIPITATION-P 2.00 INC I SLOPE - S 0.16 FT/F l 1 = 7.22 MIN� �� Kupfeerer Short Plat BASIN AREA SF ACRES - CONTRIBUTING BA`�IN SITE AREA 28048 0.64 OFF-SITE AREA 0 0.00 0.64 SOIL TYPE Idianola (InC) Type "A" EXISTING CONDITIONS DEVELOPED SINGLE FAMILY LOT 26600 0.61 ACRES CN 86 EXISTING HOUSES & ROADS 1448 0.03 ACRES CN 98 PERVIOUS 0.61 CN 86 IMPERVIOUS 0.03 CN 98 DEVELOPED CONDITIONS HOUSES AND DRIVEWAYS 6000 0.14 ACRES CN 98 PRIVATE ROAD 1600 0.04 ACRES CN 98 LANDSCAPING 16448 0.38 ACRES CN 86 � 0.55 j PERVIOUS 0.55 CN 86 'I IMPERVIOUS 0.17 CN 98 �2 , KING COUN 'I' Y, WASHINCTON, SURFACE WA7' ER U ►; SIC; N MANUAL _ _--- - -- --- _ _ --- - ------- FIGURH 3.S.1C 2-YHAR 24-IIOUR ISOPLUV[ALS .\ ` � � L' ',� ��A -� �, .�a � �'`' � ,�� ` ' \� '\ � � ,. ` .r- �.- -' � � __ ,_��zl�' � J �' � ` � �� .�.. - ��. t l .� , ) �� 1'� �� E� .�� , r�; � _ � i� �, - -- , A„ � ti � � � ��.I. ��' �`��' i� ,..-� ,.�: . �`�: �� ' ��, � .�� R�.� �� 4�� < ,.��;. � � X� � - i�� ( �'1 " �! �. ��. �., ., N �� _ - _ - � �� _ - -�' . 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SURFA (: E WA '1' F; R I) ESI (: N A1ANliA I, s _. f�lCU1tF:3.5.111 100-YEAIi 24-IIUUR ISUPI,UVIAI.S -- - - - - 3.p - � , � �. � -� ��, -. - ,�. �� ,� 3 r � � - � `„ �. �y� ' • .� � ' � ;,� �2 -�> �� , , � `� i� � �'.R ��'.�", ,.�' � , _ .,,,,,;'�'.�- 4 �_ � ! � �l F� � 36 � �1 .� , , �- _ �� , 'S� -- 3 `�1 " 3 `'� � j , � .� _�� • � - - 7 . ; ;�, RIA r � � ..9 _ �� a �`, � � A � _ �+ . 1 �. 4 0 -_ . �� _ ;�,}?�'� � .y � '�L �� , ` , � �� rq-- ��,� j�- i � _ " -. .�' , • y !I. 6' ! > 42", �; � ' z��: �.�-- , w�� _ _ � �; � 4 � � I ^ `i �F' ' '�r � � 4,3 � ---� � �-. �r � - � _.. _:\, � O � ' , 44 --E _ tiy. «� - : . � �' �p• i . i - � � ' . ,�'� i, � ` f �,= 1 � (n --� - f• 4S � "� � ,:�� r - _ � �' i� — _ `�, ' 1.�. _ •�.. :;r f i�� _ � y: � I` � � / �. •..-- _ � 1 :�"' � � 5 • _. 9is �� • l�� - fi ' . S '= y �.... _ '�1., . .....i�., !_ ` � � � � � r = t� �I ' ' - �� ' -- ✓~~ `• \ \ I � `i-� ° �� (�� • l � _ '!�`_ - � t+ �` � II- � •._ c < ' � ��— �_ 1` _ o � ` � /, _ j l� �� " ? �� \ _ � j � ': � .� i �� [. � , _ � ' _ _� '� �,a =:� ��'� 4 , - ' `�` �� = � _ _, � ;" �" �? � ,.� �� . - .� � ,..�. `, �� .. � l -� , ..�_. _ _� 7-�""� � -'� � � '� - - , I `�� _, ' �� S - � „ s n _1 � � � ,_ �, ' ' ;".i ` ' � ;� .� `. �� '"-,� �� ' ' _ ,. � r ,� � � �'� _ <I t� �` . �� '" 1 --� � �� _,.. ��. f � . . �._ l � �( _f _ �' d._ �� ,� � � ,�� - — �- — �� :� � �, � , '� ... r � � � _ ' �. �- � � � � :� �� . ;, r� °"-' �� ' � _ �� ;,�' �_��- - ---- ;� —�' - _ ` � .,� � � _ � r� � f� f `. --, � �� ( �� 1' r: ' �` � _ <.,.. �- 1 � �•�� u �, �� , j ° � I ��`-� „�,,,; �-_-� _� � � `� 0'` p . � 'o� 7•'� - - � ._.. s�f. 0�• ^�� ' � 100-YEAR 24-HOUR PRECIPITATION � � F .� ` � � 6.5 i 3.4-^—ISOPLUVIALS OF 100-YEAR 24HOUR �`O� - •� -� . , —._ . ¢� 0� cy i ' �,. .. � ��- `�' ,� — 5.5 TOTAL PRECIPITATION IN INCNES Q�• � ��.' \ ,� ' - - a� a, . ��- , �_ ' _ � O 1_2 3 4 5 6 7 _B Mlles (, �(��,� � � --,'? � ',i(}•� r \ 3.5.1-13 a� (�o 1�,�.J � 1:300,Ap0 ✓ G�� )�) J ;� :�BUFi/SCS METF�OD FOR COMPiJTING RUNOFF HYDROGRAPH S`1'ORM OPTIONS : 1 S . C. S . 'I'YPE-lA 2 - 7-llAY DESIGN STORM 3 - STORM DATA FILE ;�PECIFY S�t'ORM UPTZc)N : i S . C . S . 'PYPE-1A RAINFALL DISTRIBUTION f�,NTER : FREQ (YEAR) , DURATION(HOUR) , PRECIP (INCHES) � , 24 , 2 " ******************* S .C. S . TYPE—lA DISTRIBUTION ******************** " " * * " " " * * 2_yEAR 24—HOUR STORM **** 2 . 00" TOTAL PRECIP . *** ****** !sN'I'I.k : A (PERV) , CN (PERV) , A(IMPERV) , CN (IMPERV) , TC FUR BAS IN NO . 1 h l , t3E, , . Ui , 98, 11 . 01 [)A'I'A PR I N`I —OUT: AKEA (ACRES) PERVIOUS IMPERVIOUS TC (MINUTES) A CN A CN . 6 . 6 86 . 0 . 0 98 . 0 11 . 0 ��EAK-� (CFS) T-PEAK (HRS) VOL (CU-FT) 12 7 . 83 2070 E�NTEk [d: ] [path] filename [ . ext] FOR STORAGE OF COMPUTED HYllROGRAPH: � : 2yrex �PECIFY; C - CONTINUE, N - NEWSTORM, P - PRINT, S - ST�P - - - - --- - - - - - -- - - - - - - -- --- - - ----- - - - -- -- - ---- - - - -- -- - - - - - - - - -- - - - - -- - - ��,IV`1 ER : A(FERV) , CN (PERV) , A (IMPERV) , CN(IMPERV) , TC FOR BAS IN NO . 2. '�5, �369 . 17 , 98, 7 . 22 llA'I'A PRINT-OUT: !�K�;A (.�CKES) PERVIOUS IMPERVIOUS TC (MINUTES) A CN A CN . , . 6 86 . 0 . 2 98 . 0 7 . 2 PF�'AK Q (C'FS) T-PEAK (HRS) VOL (CU-FT) . 19 7 . 83 2789 fsN'I'ER [d: ] [path] filename [ .ext] FOR STORAGE OF COMPU`I'ED HYDROGRAPH : c: : 2yrd S��ECIF'�' : (' CONTINUE, N — NEWSTORM, P — PRINT, S — S`i'�)P �3 ii S'I'O1�M OPTIONS : 1 - S .C . S . TYPE- lA :' '1-llAY DESIGN STORM � S 1'ORM DATA F I LE SPECIFY S'I'URM OPTION: L S .C. S . TYPE-lA RAINFALL DISTRIBUTION �N'I'ER : FREQ (YEAR) , DIIRATION (HOUR) , PRECIP ( INCHES) 10 , 24 , 2 . 9 " � k**�' * ************* S .C. S . TYPE-lA DISTRIBUTION ******************* ' " " * * ***** 10-YEAR 24-HOUR STORM **** 2 . 90" TOTAL PRECIP . ******* * * I�,N'I'�,[z : A(PERV) , CN (PERV) , A(IMPERV} , CN(IMPERV) , TC FOR BAS IN NO . 1 �� 1 , 86 , . 03 , 98, 11 . 01 i�A'1'A PRINT-OUT: ARL'A (ACRES) PERVIOUS IMPERVIOUS TC (MINUTES) A CN A CN . 6 . 6 86 . 0 . 0 98 . 0 11 . 0 PEAK-Q (CFS) T-PEAK (HRS) VOL (CU-FT) . 25 7 . 83 3779 �,N'I'ER [d: ] [path] filename [ . ext] FOR STORAGE OF COMPUTED HYDROGRAPFi : � : l0yrex SPECIFY: C - CONTINUE, N - NEWSTORM, P - PRINT, S - STOP � i�.NTER: A(PERV) , CN(PERV) , A(IMPERV) , CN(IMPERV) , TC FOR BASIN NO . 2 55 , 86, . 17 , 98, 7 . 22 I �A'1'A PRINT-OUT: AREA (ACRES) PERVIOUS IMPERVIOUS TC (MINUTES) A CN A CN . '/ . 6 86 . 0 . 2 98 . 0 7 . 2 �'h'AK Q (CFS) T-PEAK (HRS) VOL(CU-FT) . 34 7 . 83 4794 tr,N'P�'K [d: J [path] filename ( . ext] FOR STORAGE OF COMPUTED HYI�ROGI2APH : c� : l0yrd :�1�EC1 FY: C - CONTINUE, N -- NEWSTORM, P - PRINT, S - STOP /� ii ` S'l'OKM UP`1'1ONS : I S . C . S . 'I'YPE-lA 2 '! -UAY DESIGN STORM 3 - STORM DATA FILE SPECIH�Y STORM OPTION: 1 S .C. S . TYPE-lA RAINFALL DISTRIBUTION ENTER: FREQ (YEAR) , DURATION (HOUR) , PRECIP (INCHES) 100, 24, 3 . 9 ' " * ******* ********** S .C.S . TYPE-lA DISTRIBUTION ******************** ********* 100-YEAR 24-HOUR STORM **** 3 . 90" TOTAL PRECIP . ********* �NI'�R : A(PERV) , CN (PERV) , A (IMPERV) , CN(IMPERV) , TC FOR BASIN NO . 1 b1., 86 , . U3 , 98 , 11 . 01. 13A'PA PRIN`I'-OUT: AREA (ACRES) PERVIOUS IMPERVIOUS TC (MINUTES) A CN A CN . 6 . 6 86 . 0 . 0 98 . 0 11 . 0 PEAK-Q (CFS) T-PEAK (HRS) VOL (CU-FT) . 40 7 . 83 5832 ENTER [d: ] [path] filename [ .ext] FOR STORAGE OF COMPUTED HYDROGRAPH: I� �OmQH�xex i SYECIFY : C - CONTINUE, N - NEWSTORM, P - PRINT, S - STOP II c ! ENTER: A(PERV) , CN (PERV) , A (IMPERV) , CN(IMPERV) , TC FOR BASIN NO_ 2 . 55, 88 , . 17 , 98 , 7 . 22 � 1)A`I'A PRINT-OU'P: AREA (ACRES) PERVIOUS IMPERVIOUS TC (MINUTES) A CN A CN . 7 . 6 86 . 0 . 2 98 . 0 7 . 2 PEAK-Q (CFS) `P-PEAK (HRS) VOL(CU-FT) . 51 7 . 83 7164 ENTER [d : ] [path] fileiiame [ .ext] FOR STORAGE OF COMPUTED HYDRUGRAPH: c : lOUyrd SPECIFY: C - CONTINUE, N - NEWSTORM, P - PRINT, S - S`I'OP �� , KING COUN 'I' Y, WASHINGTON, SURFACE WATER DESIGN MAIEUAL o A licensed septic system designer or suitably t�ained person working under the supervisior of a licensed Professional Engineer shall make an inspection of the soil after the system is excF rated, before the trenches are filled with rock to confirm that suitable soils a�e present. Method of Analysls/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 4.5.1 B. The length of trench required is determined by dividing the �oof �rea by 1000 and multiplying by the unit length I from the chart for the soil type and multiplying the r:fsult by the regional scale factor k shown in Figure 4.5.1 D. The trench length L is computed using thF following equation: L = (AR/10001{I)ik} Where: AR = area of the roof tributary to the system, ft�. (Note: a typical single-family residence has a �oof area of approximately 2,000 ft�.) I = the unit length of trench required per 1,000 ft2 of roof area from Table 4.5.1 B, ft"' k = the regional scale factor from Figure 4.5.1 D. TABLE 4.5.1B 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 Trei ch ft2 of Roof - Sea Tac per 1000 ft� of Rc �f - Landsburg 1. Coa�se sa�ds o� Cobbles 15 20 2. Medium sand - 25 30 3. Fine sand, loam sand 60 75 4. Sand loam 100 125 5. Loam 150 190 I' Example: Proposed residence located at Kent East Hill Roof area iAR) = 2,U00 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 ' � = (2000/10001160►11.0) = 120 ft (Note: could be accomplished by two trenchesl. �j 4.5.1-3 i l l94 �_i�� • KING COUN'I'Y, WASFIINGTON, SURFACE WATER DESIGN MANUAL FIGURE 4 S lD REGIONAL SCALE FACTORS ` r`-._._-y^ .... "' � f.►'-'__,�-� _ _r i_ �. ', ",_�. -�; __ _'__ .. .} �,^� � � `' '� '� � P I� � '�i � T - � I I (IJC ,H�rl ��r-�Z ,�f�� f �t� � � t. _ - �� , _�,i -�� "' ��, `�. � .� �t '=j .�, �1� _, � � ...., �� .��-� �� ' ��_ -�• ) ,_, '� , ; , �' � .5 �, � � �`' ;_�� , _ ,, �, �c - �, � �l �� ` _ _ _ � / `�, �� '1 .'?'S r � � �7 � � � , - -� � �� j� �� : �..� � I.� r ' � / ` a� �� -�,I � �-^� �1 ��. .'. �.�,.� 1 , �' �_ �� 't- �a � � ��*� - - �� i , � . �� .�� 1 f • „ � ��_�� 1' , ✓d '�' �� ,. ' 1 �l�� `+ �� .�,s .i �� ,�. �._� � � / �1 % �'( �4 `o� __ ' I� ' � _.ny �r'/ , / ' G. � ' R. _ �- �� - � _- � '�y ;' ,,� , '� � '� � ` ;% ��'`' � '.,k t , �l, � 'r �� '`, 1l/S �i " � � .F-� � � �_� f� � l- '� �► � � �� , � �� ,� � � ,'�'�T. `' ' ; "l�` \�� _ _{� .�-� � �.�- - � �t ti r�T .�� - ', � l `- .,.,.a - - � � - �ts ,•;.�� f r- � _ �� . ..Ji , r-- ,.i�� , _ � r SF.ATAC J* �.. ��_��i~ r, � �� ,._. J�� % � ��I� !! � '� o � `��1 `2\ _ � " y/ f � �,,M -� �� \ � _ _ ! , _ .�\ _ � F �� +� �. __�' \ � ?� � :�\ .„` '�' _� \ , m "� .-�:� r L""d`b`°g• ... I'y . � � �' '� a /�� / ,� � ',a �� , '� - r 4 il _ - 'f �l-� ! � �� I ..��' _ � � �. � i •;��.. �� ;.., �) � -, �'�- _ __ �.�._� � _� '� ��'� �� ;�,�� _�.�� > �'� � `^f —,' _ �'� f�=•r - � ;7 � _ > f:,:; ; - �l�� .- ,,,� �'��,�_� J ... G„� ♦ ; -�,,, � ; .� I C-(�t :T � - � c�- � % � � ; �` ' �:�,, '' � � ,:¢ � `�� J/� T�cotiu� ~ •�� ` ' ..';,i ' ' � rJ� , �� -7_�.. � �- :�� / `�� 1 }.. ••t , i 1 %,r r � I � \�\ ii� ��+-�P_ L'i::.l._.r1.1 '� � �t�+ -1n. � .I� � ��1 '1 j� y f � _`__._. ��` � 1 ".� .� . �� _ ---- ; �l � � � , _ - � 1 ..� s-r t.i ��,� � ` - � -.`r" ST IA J; "'J � / �� % , '_� `" �'' 1 , � 0 �`�j -.�-. �, . I , , � ��. `��j�' y'" I' ��_ _ j` N sT l.o t.n o.s �,,�, �-"t� ..i �!,.,�__ Y /��- � C•:. ::: � ..i �� `-- �-' LA 1.1 MilfS � � 2 3 � 5 E �--�C�� -i � LA 0.9 LA 1.0 11/94 � 4.5.1-7 CB ' 7RENC , ��., i �TRE'NCN �� L-�' CB POSSIBLE ALIGNMENTS P L ,q N VI E {/ y ROOF DRA/N OBSERVA T10N WELL N.T.S. ROOF ,--- -------------------� I I I i . . INFIL TRA 770N TRENCH� �SUMP OR CA TCH BASIN 6"m PERFORATED P/PE W/SOLID LID (C.P.E.P. SINGLE WALL ACCEPTABLE) �ROOF DRA/N PRO�IL E 1/lE W SPLASH BLo�K N.T.S. CA TCH BASIN SUMP WI TN OBSERVA710N WELL SOLID UD I A SHEET COVER MATER/AL ' � I' \�\�\\�� \� \� �i �� - ------------------ J' Mir�_ MlN. r . • LEVEL. 1 � 1' M/N. i i' i�.. M/N. 1:•. :. f =- � " --------�_� -� FINE MESH LEVEL SCREEN A 5. 6" PERFORA TED P/PE , I (C.P.E.P. SINGLE WALL ACCEPTABLE) VARIES (SEE PLAN) 10' M/N. OBSER VA TlON WELL W17N METAL CAP & LOCK. 6" PVC PIPE �\ 6�M�N � / COMPACT BACKFILL (PERFORA TED) \\ . � � . .. �� WRAP TRENCH 6"� PERFORA TED PlPE EN77REL Y WI TH WASHED ROCK 3/4"--1-1/2" F!L TER FABRIC. ��\ 2' SEC T101�l �1 — �-1 V. CONVEYANCE SYSTEM ANALYSIS The proposed storm system consists of one 12-inch pipe (double wall pipe; conveying runoff from the site. The 100-year developed runoff from the site calculated at 0.51 cfs. All 12-inch pipes proposed for this development exceeds the minimum of 1 J percent slope. The attached calculation determined that the proposed pipe �t a minimum of 1.0 percent slope carries 3.86 cfs, more than 0.51 cfs anticipated for 100-year flows during post development. � -/� � tm�#1 . txt I . P�Ianninq Pipe Calculator � Given l:nput Uata: Shape . . . . . . . . . . . . . . . . . . . . . . . . . . . Circular :�olving for . . . . . . . . . . . . . . . . . . . . . Flowrate l?iameter . . . . . . . . . . . . . . . . . . . . . . . . 12 . 0000 in 1_�epth . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 . 0000 in tlope . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 0100 ft/ft Manning' s n . . . . . . . . . . . . . . . . . . . . . 0 . 0120 �_:om��uted Results : I��l.owrate . . . . . . . . . . . . . . . . . . . . . . . . 3 . 8597 cfs Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 7854 ft2 vVetted Area . . . . . . . . . . . . . . . . . . . . . 0 . 7854 ft2 Wetted Perimeter . . . . . . . . . . . . . . . . 37 . 6991 in 'erimeter . . . . . . . . . . . . . . . . . . . . . . . 37 . 6991 in %elocity . . . . . . . . . . . . . . . . . . . . . . . . 4 . 9143 fps ��ydraulic Radius . . . . . . . . . . . . . . . . 3 . 0000 in Percent Full . . . . . . . . . . . . . . . . . . . . 100 . 0000 ° �'ull flow Flowrate . . . . . . . . . . . . . . 3 . 8597 cfs F'ull flow velocity . . . . . . . . . . . . . . 4 . 9143 fps Page 17 . i� V1. SPEC:IAL RF:POR I�S and STtIDtES: . iz V11. F3ASIN and COMMUNITY PLANNING AREAS VIII. OTHER PERMITS /9 4 � IX. EROSION & SEDIMENTATION CONTROL The contractor shall install a silt-fence along the perimeter and a 100ft by 15ft by 12"thick construction entrance made of quarry spalis. See Temp. Erosion/ Sedimentation Control Plan. Sediment Trap: SA = FS*Q2Ns ; pond Surface Area FS= 2 Vs= 0.00096 ft/s Q2= 0.20 cfs.; See isopluvial and hydrograph calculation below Thus SA = 417 square feet _� , ' . GEOTECHNICAL ENGINEERING STUDY 4-Lot Short Plat 2027 Northeast 21 st Street Renton, Washington This report presents the findings and recommendations of our geotechnical engineering study for the site of a proposed 4-lot short plat located at 2027 Northeast 21 st Street in Renton. We were provided with a topographic map of the site prepared by Schroeter Land Surveyi�ig and dated July 11, 2001. Development of the prope�ty is in the planning stage, and detailed plan� were not made available to us. A sketch of the four proposed lots was provided. Ba�sd on conversations with Larry Kupferer, we anticipate that the development will consist of the cre�tion of four lots on the property. The existing house (#2027) will occupy one of these lots. An .ccess roadway will need to be constructed from Harrington Place Northeast to the three new hous� sites. Cuts, fills and retaining structures will needed for this driveway. Detailed grading informati� n was not indicated on the provided plans. We anticipate that the two lots�n the west side of the : ite will have houses with daylight basements. ��3 If the scope of the project changes from what we have described above, we should be pi �vided with revised plans in order to determine if modifications to the recommendations and conclus �ns of this report are warranted. SlTE COND/TIONS SURFACE The Vicinity Map, Plate 1, illustrates the general location of the site. The property is rectangular in shape and is currently occupied by the Kupferer residence (#2027) located on the soukheast portion of the site. Northeast 21st Street at borders the east half of the south property lin�;. The house site and the southeast quadrant of the property are relatively level and the land arot��d the house is mostly lawn. To the west of the house is a relatively steep, 14-foot-high slope. ThE upper portion of this slope was obviously over-steepened by filling when the house was bui . An approximate 4-foot cut was made into the toe of the slope in the past. The central portior of the slope appears original and is only moderately inclined. The land at the base of the slope � then relatively level to the west property line. There were no indications of recent slope instability risible at the time of our site visits. The north one-half of the site has a gently to moderate slopE to the west-northwest. There are some large evergreen trees on this slope. The remainder of thE site is cleared or has low brush. ' SUBSURFACE ' The subsurface conditions were explored by excavating four test pits. We also logged tv:� pre- I existing shallow test pits. The approximate locations of the test pits are shown on tr�� Site Exploration Plan, Plate 2. Our exploration program was based on the proposed constr action. anticipated subsurface conditions and those encountered during exploration. and the scope cf work outlined in our proposal. �;Ev;;�;.�; : �.;��,�;��t1F,h�:: ir�: , �DK Construcfron JN 03099 I he test �its were excavatea on Nlarcn ��, �UU,i witn a rubr�er-tirea uacrcnoe. ti yeoiE ;nni� enaineer from our staff observed the excavation process and logaed the test pits The -! �st i I L '' All of the test pits encounterea sous. i esc Nit b, �ocatea in the iawn at tne top or tne sic � encountered about 3 feet of fill soils overlying medium-dense, silty sand. Some of the t?� pits encountered a thin layer of dark-brown topsoil, but the primary topsoil is a reddi�f� brown, silty sand loam. This loam generally overlies relatively clean, fine- to medium- grained sands that were medium-dense. The conditions encountered in our test pits are consistent with those we have observed on previous projects in the vicinity. No obstructions were revealed by our explorations. However, debris, buried utilities, and old foundation and slab elements are commonly encountered on sites that have had previous development. Although our explorations did not encounter cobbles or boulders, they �re often found in soils that have been deposited by glaciers or fast-moving water. Groundwater Conditions No groundwater seepage was observed in the test pits. The test pits were left open for c nly a short time period, but there were no indications of wet soils or perched groundwater It should be noted that groundwater levels vary seasonally with rainfall and other fact� rs. However, we do not anticipate that a significant amount of groundwater will be found v►vi �in the depths of the explorations. Subsurface conditions can vary between exploration locations. The logs provide s pecific subsurface information only at the locations tested. The relative densities and m�isture descriptions indicated on the test pit logs are interpretive descriptions based on the cor ditions observed during excavation. The compaction of backfill was not in the scope of our services. Loose soil will therefore bE found in the area of the test pits. If this presents a problem during site development, the backfill wi'I need to be removed and replaced with structural fill during construction. CONCLUSIONS AND RECOMMENDATIONS GENERA[. THfS SECTION CONTAlNS A SUMMARY OF OUR STUDY AND FIIVDINGS FOR THE PURPOSE 3 OF A GENERAL OVERVlEW ONLY. MORE SPECIFIC RECOMMENDATIOIVS AND CONCLUSlO11,'S ARE CONTAlNED /N THE REMAINDER OF THlS REPORT. ANY PARTY RELYING ON TNlS REPORT S�OULD READ THE ENTlRE DOCUMENT. The site soils encountered in the test pits were generally native sands. These soils ai � well- drained and will provide good support for retaining walls and building foundations. Use of a �mooth backhoe bucket to excavate the footings is recommended, in order to limit disturbance of the subgrade soils. The cleaner sands that underlie the topsoil are also suitable for use as wall �ackfill and structural fill. Because the sands are relatively fine-grained and clean, often a sig iificant compactive effort and the addition of moisture is necessary to compact the soils. �._;f OTE:_H �:ON�ULTA.NTS IhJ(; � LDK Construc6on J! 03099 ,, April 2, 2003 Page 3 A factor in development of the property is the slope on the west side of the existing �ouse According to the site survey by Schroeter Land Surveying, this slope is 14 feet high. The test pits and visual observation indicates that the lower approximate 4 feet of the base of the slope was steepened by mining of sand, and the top was oversteepened by placement of fill when the house was constructed. II Between this fill slope and the mined base, the slope is actually less steep than indicated on the ��', topographic map. It is our opinion that this slope, as it currently exists, is stable and t :at the development will increase the stability of the slope, since the toe of the slope will neec to be regraded for the house construction or be retained by walls constructed for daylight base nents. The proposed development should not adversely affect stability of the site or the surr� �nding properties, if the recommendations of this report are followed. ' Some grading will be necessary for the access roadway to the new lots. Retaining structurs.s may be constructed by a variety of inethods, including concrete walls and slopes faced with rock� ries or concrete blocks. The concrete block or rockeries would be reinforced with geogrid in the fill �ehind the facing. We can provide specific design criteria for walls when a site-grading plan is devE loped. General soil parameters for retaining walls are contained in a later section of this report. Even in the absence of active seepage into and beneath structures, water vapor can riigrate through walls, slabs, and floors from the surrounding soil, and can even be transmitted fro�r slabs and foundation walls due to the concrete curing process. Water vapor also results from oc;upant uses, such as cooking and bathing. Excessive water vapor trapped within structures can res:�lt in a variety of undesirable conditions, including, but not limited to, moisture problems with flooring systems, excessively moist air within occupied areas, and the growth of molds, fungi, anr other biological organisms that may be harmful to the health of the occupants. The designer or ai:hitect must consider the potential vapor sources and likely occupant uses, and provide su"ficient ventilation, either passive or mechanical, to prevent a build up of excessive water vapor witi iin the planned structure. The erosion control measures needed during the site development will depend heavily �n the weather conditions that are encountered. Most rainwater infiltrates into the ground. We an cipate that the existing silt fence will need to extend around the downslope sides of the site. � ocked construction access roads should be extended into the site to reduce the amount of mud car ied off the property by trucks and equipment. Cut stopes and soil stockpiles should be coverf d with plastic during both dry and wet weather. This prevents erosion, and maintains the soil's rr �isture content during dry weather. Following rough grading, it may be necessary to mulch or hya oseed bare areas that will not be immediately covered with landscaping or an impervious surface. SEISMIC CONSIDERATIONS The site is located within Seismic Zone 3, as illustrated on Figure No. 16-2 of the 1997 ��niform Building Code (UBC). In accordance with Table 16-J of the 1997 UBC, the site soil profilE within 100 feet of the ground surface is best represented by Soil Profile Type S� (Very Dense Soilj. The site soils are not susceptible to seismic liquefaction because of their dense nature and the at sence of near-surface groundwater. GE.�.�'E�._�;! i.i.��l;i!1I � '�fJ' . Ir.�' � U{' �� r�l':»ir�:r:f��il�, i� �?�1G�� la.�)('�I ,_ �'''1;,. �2.U� -� CONVENTIONAL FOUNDATIONS The proposed houses can be sup�orteu on �onventiona� continuous aiiu s�read footinys � �arn ; on undisturbed native, medium-dense sands, or on structurai fill piaced above these sand�. Sef the section entitled General Earthwork and Structura/ Fil! for recommendations regard .�g th� placement and compaction of st�uctural fill beneath structures. Adequate compaction of str.�ctur� fill should be verified with frequent density testing during fill placement. Prior to placing struct aral fi beneath foundations, the excavation should be observed by the geotechnical engineer to documer� that adequate bearing soils have been exposed. We recommend that continuous and individu�� spread footings have minimum widths of 12 and 16 inches, respectively. Footings should also b� bottomed at least 18 inches below the lowest adjacent finish ground surface. The local buildin: codes should bP rPviewed to determine if different foot�na widths o� embedment �lent'�� a� requirec; An allov� � � — � � � �-� �� -� � -� �� -,- ._:__ _ � supported on competent native soil. A one-third increase in this design bearing pressure niay be used when considering short-term wind or seismic loads. For the above design criteri��, it is anticipated that the total post-construction settlement of footings founded on competent nati�:�e soil, or on structural fill up to 5 feet in thickness, will be about one-half inch. Lateral loads due to wind or seismic forces may be resisted by friction between the foundati �n and the bearing soil, or by passive earth pressure acting on the vertical, embedded portions of the foundation. For the latter condition, the foundation must be either poured directly against re atively level, undisturbed soil or be surrounded by level structural fill. We recommend using the fo �owing ultimate values for the foundation's resistance to lateral loading: , � ' Coefficient of Friction 0 40 Passive Earth Pressure 350 pcf Where:{i)pcf is pounds per cubic foot,and(ii)passive earth pressure is computed using the equivalent fluid density. We recommend maintaining a safety factor of at least 1.5 for the foundation's resistance to lateral loading, when using the above ultimate values. PERMANENT FOUNDAT/ON AND RETAINlNG WALLS Retaining walls backfilled on only one side should be designed to resist the lateral earth pre:�sures imposed by the soil they retain. The following recommended parameters are for walls that r�strain level backfill: r;rr�,�r�Fl r�nN�Ui 'A�J';', ;�d�. LDK Co�rsfructron J� 03099 � April 2, 2003 Page 5 Active Earth Pressure ` 35 pcf I� Passive Earth Pressure 350 pcf - Coefficient of Friction 0.40 Soil Unit Weight 125 pcf Where: (i) pcf is pounds per cubic foot, and (ii) active an-' passive e , pressure� " For a re height,a of the wa pressure. The passive pressure given Is a�{�i u��iate �u� �nc ue�u� �i ievei s��u�iu�d� iiii ��dceu ir� ii c �t o retaining or foundation wall only. The values for friction and passive resistance are ultimate value and do not include a safety factor. We recommend a safety factor of at least 1.5 for over�urnir� and sliding, when using the above values to design the walls. Restrained wall soil para-nete� should be utilized for a distance of 1.5 times the wall height from corners or bends in the walls. This is intended to reduce the amount of cracking that can occur where a wall is restraine� by a corner. The design values given above do not include the effects of any hydrostatic pressures beh nd the walls and assume that no surcharges, such as those caused by slopes, vehicles, or a� jacent foundations will be exerted on the walls. If these conditions exist, those pressures should be added to the above lateral soil pressures. Where sloping backfill is desired behind the walls, we'w: 1 need to be given the wall dimensions and the slope of the backfill in order to provide the appr �priate design earth pressures. The surcharge due to traffic loads behind a wall can typic �Ily be accounted for by adding a uniform pressure equal to 2 feet multiplied by the above acti�e fluid density. Heavy construction equipment should not be operated behind retaining and foundation wall�, within a distance equal to the height of a wall, unless the walls are designed for the additional lateral pressures resulting from the equipment. The wall design criteria assume that the backfill will be well-compacted in lifts no thicker than 12 inches. The compaction of backfil! near the walls should be accomplished with hand-operated equipment to prevent the walls from being overloadec by the higher soil forces that occur during compaction. Retainin_q Wall Backfill and Waterproofin_q Backfill placed behind retaining or foundation walls should be coarse, free-drair ng structural fill containing no organics. This backfill should contain no more than 5 percent silt or clay particles and have no gravel greater than 4 inches in diameter. The cleaner na'ive gray-brown sands are suitable for reuse as wall backfill. GEOTECH CrJNSULTANTS, INC LDK Construction J�' 03099 - April 2, 2003 �age 6 Silty soils should not be used as wall backfill to prevent a build-up of hydrostatic press:re behind the wall. However, the top 12 to 18 inches of the backfill should consist o" a compacted, relatively impermeabte soil or topsoil, or the surface should be paved. T�e ground surface must also slope away from backfilled walls to reduce the potential .�or surface water to percolate into the backfill. The section entitled Genera/ Earthwork a�d Structural Fill contains recommendations regarding the placement and compaction of structural fill behind retaining and foundation walls. The performance of subsurface drainage systems will degrade over time. Therefore, waterproofing should be provided where moist conditions or some seepage through the walls are not acceptable in the future. This typically includes limiting cold-joints and wall penetrations, and using bentonite panels or membranes on the outside of the wafls. Applying a thin coat of asphalt emulsion is not considered waterproofing, but will only help to prevent moisture, generated from water vapor or capillary action, from seeping throu�h the concrete. With any project, adequate ventilation of basement and crawl space area� is important to prevent a build up of water vapor that may be transmitted through concrF�te walls from the surrounding soil. SLABS-ON-GRADE The building floors may be constructed as slabs-on-grade atop native non-organic soils, or on structural fill. The subgrade soil must be in a firm, non-yielding condition at the time � f slab construction or underslab fill placement. Any soft areas encountered should be excavatf d and replaced with select, imported structural fill. All slabs-on-grade should be underlain by a capillary break or drainage layer consistiR�; of a ' minimum 4-inch thickness of coarse, free-draining structural fill with a gradation similar � that discussed in Permanent Foundation and Retaining Walls. This capillary break/drainage 1-�yer is not necessary if an underslab drainage system is installed. As noted by the American Cc�crete Institute (ACI) in Section 3.2.3 of the Guides for Concrete Floor and Slab Structures, aroper moisture protection is desirable immediately below any on-grade slab that will be covered by tile, wood, carpet, impermeable floor coverings, or any moisture-sensitive equipment or products. ACI � also notes that vapor retarders, such as 6-mil visqueen, are typically used. A vapor reta.�der is defined as a material with a permeance of less than 0.3 US perms per square foot (psf) per hour, as determined by ASTM E 96. It is possible that concrete admixtures may meet this specification, although the manufacturers of the admixtures should be consulted. However, if no poten�ial for ' vapor passage through the slab is desired, a vapor barrier should be used. A vapor barr;er, as defined by ACI, is a product with a water transmission rate of 0.00 perms per square foot pc�r hour when tested in accordance with ASTM E 96. Reinforced membranes having sealed overla�s can meet this requirement. In the recent past, ACI (Section 4.1.5) recommended that a minimum of 4 inches of well-�raded compactable granular material, such as a 5/8 inch minus crushed rock pavement base, shc uld be i placed over the vapor retarder or barrier for protection of the retarder or barrier and as a "blc�ter" to aid in the curing of the concrete slab. Sand was not recommended by ACI for this p�.rpose. However, the use of material over the vapor retarder is controversial as noted in curre it ACI literature because of the potential that the protection/blotter material can become wet betwE�n the ' time of its placement and the installation of the slab. If the material is wet prior to slab plac�ment, which is always possible in the Puget Sound area, it could cause vapor transmission to oc�ur up GEOTECH CONSULTANTS, INC. r LDK Constructron JP� 03099 � April 2, 2003 Page 7 through the slab in the future, essentially destroying the purpose of the vapor barrier/retarder. Therefore, if there is a potential that the protection/blotter material will become wet before the slab is installed, ACI now recommends that no protection/blotter material be used. However, ACI then recommends that, because there is a potential for slab cure due to the loss of the blotter material, joint spacing in the slab be reduced, a low shrinkage concrete mixture be used, and "other measures" (steel reinforcing, etc.) be used. ASTM E-1643-98 "Standard Practice for Install.�tion of Water Vapor Retarders Used in Contact with Earth or Granular Fill Under Concrete Slabs" generally agrees with the recent ACI literature. We recommend that the contractor, the project materials engineer, and the owner discus:� these issues and review recent ACI literature and ASTM E-1643 for installation guidelines and gtlidance on the use of the protection/blotter material. Our opinion is that with impervious surfaces �hat all means should be undertaken to reduce water vapor transmission. ROCKERIES We anticipate that rockeries may be used in the site development. A rockery is not interded to function as an engineered structure to resist lateral earth pressures, as a retaining wall wo ald do. The primary function of a rockery is to cover the exposed, excavated surface and thereby retard the erosion process. We recommend limiting rockeries to a height of 6 feet and placinq them against only medium-dense to dense, competent native soil. Geogrid-reinforcing in a backfilled zone would be required for taller rockeries, or those that would support surcharges, such �s from vehicles. The Iower 12 inches of any rockery must be embedded below the finish grade t.�at will exist at the face of the rockery. Rockeries that are taller than 6 feet, or that are placed in �ront of loose soil or in areas of compacted fill will require additional engineering. Plate 6 illustrates c,eneral , considerations for cut rockeries. I The construction of rockeries is, to a large extent, an art not entirely controllable by engi�,�eering methods and standards. It is imperative that rockeries, if used, are constructed with care a id in a proper manner by an experienced contractor with proven ability in rockery constructior The rockeries should be constructed with hard, sound, durable rock in accordance with acceptE d local ''� practice and standards. Soft rock, or rock with a significant number of fractures or inc��sions. ' should not be used, in order to limit the amount of maintenance and repair needed ovE.r time. Provisions for maintenance, such as access to the rockery, should be considered in the de: gn. In general, we recommend that rockeries have a minimum dimension of one-third the heigh of the slope cut above them. EXCAVATlONS AND SLOPES ! Excavation slopes should not exceed the limits specified in local, state, and national gove��nment � safety regulations. Temporary cuts to a depth of about 4 feet may be attempted verti :ally in unsaturated soil, if there are no indications of slope instability. However, vertical cuts should not be made near property boundaries, or existing utilities and structures. Based upon Was iington ; Administrative Code (WAC) 296, Part N, the soil at the subject site would generally be class fied as Type B. Therefore, temporary cut slopes greater than 4 feet in height cannot be excavate•� at an , inclination steeper than 1:1 (Horizontal:Vertical), extending continuously between the top �nd the bottom of a cut. Temporary cuts should not extend below a 1.5:1 (Horizontal:Vertical} zone �loping downward from existing structures, utilities, or roads without shoring. GEUTECH CONSULTANTS, ING I ' LDK Construction J�a 03099 , April 2, 2003 Page 8 The above-recommended temporary slope inclination is based on what has been succe�sful at other sites with similar soil conditions. Temporary cuts are those that will remain unsupportE� for a relatively short duration to allow for the construction of foundations, retaining walts, or �:tilities. Temporary cut slopes should be protected with plastic sheeting during wet weather. The cut �lopes should also be backfilled or retained as soon as possible to reduce the potential for ins`ability. Please note that sand can cave suddenly and without warning. Excavation, foundation, an ! utility contractors should be made especially aware of this potential danger. All permanent cuts into native soil should be inclined no steeper than 2:1 (H:V). Fill slopes should also not be constructed with an inclination greater than 2.5:1 (H:V). To reduce the potencial for shallow sloughing, fill must be compacted to the face of these slopes. This can be accom�lished by overbuilding the compacted fill and then trimming it back to its final inclination. Adequate compaction of the slope face is important for long-term stability and is necessary to prevent excessive settlement of patios, slabs, foundations, or other improvements that may be placed near the edge of the slope. Water should not be allowed to flow uncontrolled over the top of any temporary or permanent slope. Also, all permanently exposed slopes should be seeded with an appropriate spe�.ies of vegetation to reduce erosion and improve the stability of the surficial layer of soil. DRA/NAGE CONSIDERATIONS Foundation drains should be used where (1) crawl spaces or basements will be below a str �cture, (2) a slab is below the outside grade, or (3) the outside grade does not slope downward rom a , building. Drains should also be placed at the base of all earth-retaining walls. These drains �hould � be surrounded by at least 6 inches of 1-inch-minus, washed rock and then wrapped in non-�roven, geotextile filter fabric (Mirafi 140N, Supac 4NP, or similar material). At its highest p �int, a perforated pipe invert should be at least 6 inches low the bottom of a slab floor or the le� sl of a crawl space, and it should be sloped for drainage. II roof and surface water drains must C e kept separate from the foundation drain system. A typical drain detail is attached to this report as Plate 6. For the best long-term performance, perforated PVC pipe is recommended for all subsurface drains. As a minimum, a vapor retarder, as defined in the Slabs-On-Grade section, should be provided in any crawl space area to limit the transmission of water vapor from the underlying soils. A1so, an outlet drain is recommended for all crawl spaces to prevent a build up of any water that may bypass the footing drains. The excavation and site should be graded so that surface water is directed off the site an�� away from the tops of slopes. Water should not be allowed to stand in any area where founo�tions, slabs, or pavements are to be constructed. Final site grading in areas adjacent to the � ouses should slope away at least 2 percent, except where the area is paved. Surface drains sr� uld be provided where necessary to,prevent ponding of water behind foundation or retaining walls. Water from roof, storm water, and�oundation drains should not be discharged onto slopes; it shc uld be tightlined to a suitable outfall located away from any slopesl The use of dry wells or inf tration systems appear feasible on these lots, as the soils are sands with a low fines content. GFt)TE�:I�� t_;ONSULTANTS, INC LDK Construction JR U3U9u �, - April 2, 2003 Page 9 ! GENERAL EARTHWORK AND STRUCTURAL FILL , All building and pavement areas should be stripped of surface vegetation, topsoil, organic s� il, and other deleterious material. The stripped or removed materials should not be mixed w h any , materials to be used as structural fill, but they could be used in non-structural areas, s �ch as landscape beds. Structural fill is defined as any fill, including utility backfill, placed under, or close to, a b ilding, behind permanent retaining or foundation walls, or in other areas where the underlying soil needs to support loads. All structural fill should be placed in horizontal lifts with a moisture conter,. at, or near, the optimum moisture content. The optimum moisture content is that moisture conte it that results in the greatest compacted dry density. The moisture content of fill is very importa�t and must be closely controlled during the filting and compaction process. The allowable thickness of the fill lift will depend on the material type selected, the com� action equipment used, and the number of passes made to compact the lift. The loose lift thi� kness should not exceed 12 inches. We recommend testing the fill as it is placed. If the fill is not sufficiently compacted, it can be recompacted before another lift is placed. This elirninat�s the need to remove the fill to achieve the required compaction. The following table pr �sents recommended relative compactions for structural fill: � � � Beneath footings, slabs 95% or walkwa s Filled slopes and behind 90% retainin walls 95% for upper 12 inches of Beneath pavements subgrade; 90% below that level Where: Minimum Relative Compaction is the ratio,expressed in percentages, of the compacted dry density to the maximum dry density, as determined in accordance with ASTM Test Designation D 1557-91 (Modified Proctor). Structural fill that will be placed in wet weather should consist of a coarse, granular soil with � silt or clay content of no more than 5 percent. The percentage of particles passing the No. 20C sieve should be measured from that portion of soil passing the three-quarter-inch sieve. LIMlTATIONS The conclusions and recommendations contained in this report are based on site conditic�ns as they existed at the time of our exploration and assume that the soil and groundwater cor .�itions encountered in the test pits are representative of subsurface conditions on the site. If the subsurface conditions encountered during construction are significantly different from those observed in our explorations, we should be advised at once so that we can review these co►- �itions and reconsider our recommendations where necessary. Unanticipated soil conditioi s are commonly encountered on construction sites and cannot be fully anticipated by merely tak �g soil samples in test pits. Subsurface conditions can also vary between exploration locations, Such unexpected conditions frequently require making additional expenditures to attain a p operly GEOTECN CONSULTANTS, INC � LDK Construction JP 03099 , Aprii 2, 2003 F�age 10 constructed project. It is recommended that the owner consider providing a contingency fund to accommodate such potential extra costs and risks. This is a standard recommendation for all projects. This report has been prepared for the exclusive use of LDK Construction and its representati��es for specific application to this project and site. Our conclusions and recommendations are professional opinions derived in accordance with current standards of practice within the scope of our services and within budget and time constraints. No warranty is expressed or implied The scope of our services does not include services related to construction safety precautions, and our recommendations are not intended to direct the contractor's methods, techniques, sequenc es, or procedures, except as specifically described in our report for consideration in design. ADDIT/ONAL SERVICES In addition to reviewing the final plans, Geotech Consultants, Inc. should be retained to E�rovide geotechnical consultation, testing, and observation services during construction. This is to c�nfirm that subsurface conditions are consistent with those indicated by our exploration, to e� aluate whether earthwork and foundation construction activities comply with the general intent of the recommendations presented in this report, and to provide suggestions for design changes in the event subsurface conditions differ from those anticipated prior to the start of constr iction. However, our work would not include the supervision or direction of the actual work �f the contractor and its employees or agents. Also, job and site safety, and dimensional measurernents, will be the responsibility of the contractor. Subsequent consultation and testing services during the design and construction phase would be charged on a time-and-materials basis in accordance with terms and conditions of our attached schedule of fees and general conditions. This work often includes a review of the geotechnical aspects of the plans and interaction with the architect, civil engineer, and structural engineer Also, it may involve geotechnical observation and testing services during the construction phase, which would also be charged on a time-and-materials basis. Unless otherwise notified by the owr �r, we would assume that your acceptance of this proposal is also authorization to consult with the �esign team as required on a time-and-materials basis. During the construction phase, we will provide geotechnical observation and testing servicf.s only when requested by you or your representatives. We can only document site work that we �•ctually observe. It is still the responsibility of your contractor or on-site construction team to verify t �at ��r recommendations are being followed, whether we are p The following plates are attached to complete this repor: Plate 1 Vicinity Map Plate 2 Site Exploration Plan Plates 3 - 5 Test Pit Logs ' Plate 6 Typical Rockery Detail I! Plate 7 Typical Footing Drain I�, GE�'J?��H r.��NSUL TAN1�S, INC �� , • LDK Construction JN 03099 , April 2, 2003 F'age 11 We appreciate the opportunity to be of service on this project. If you have any questions, c � if we may be of further service, please do not hesitate to contact us. Respectfully submitted, GEOTECH CONSULTANTS, INC. �� oFI �w�sy��'�- �� CO,li► � � � ��.n��'Cj�l�F'�`�'�� f'Z,I O� ss�ONAL��G EXPIRES S / �7 I O James R. Finley, P.E. Principal JRF/MRM: esm GEOTECH c;ONSULTANTS, INC • . 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I � ' r� nr �:� t.`'. � �3Q1}Ff lt4 �'�.��.� ��_� �I n .�� .410�:. 5t 1 IN 57 �� t �-0:y � � ! �� i. �PC � ' - � .i; � �I;{ ..� r• PL "� :.�1e h . t� Ti� � _ SE 118Ty $T !M � 9h1 5T � ' �' a� �i� :� fS=.: •�.-ii �'� �5��l�., F _�� C� H. �:� -- ` � � '� - P 10 I� � A ¢, ;`s1H� � ;_ � �; a .ME..� ; ��`N y., F �E� �.. -c_'NE" �7TFiPC �'�'SE 121A�S7 x - � � � s3'F� 1 a' :' i h! �„�E 122XD ,z �' a i .,.�,' r �A S l A 'Qi:. ST Q _ .; � c- NOR7H (Source: Thomas Brofhers Streef Guide and Directory) ' VICINITY MAP � GEOTECH 2O27 Northeast 21st Street CONSULTANTS, INC. Renton, Washington � � � Job No: Date: P/ate: � 03099 March 2003 Not TO SC81e � ' -- � N � ' � II� � � NE 22nd STREET � ' � 1 � a TP-5 / 3,o I,i � TP-4 � � � o � i � � o �-, � � � � � � / � � i � i � i � � � � �3�° � � � � TP-3 � 0 � 1 I ' � f � , D � TP-2 f O �� 1 f EXISTING � RESIDENCE � LEGEND: 3'/ NE 21st STREET Q APPROXIMATE TEST PIT LOCATIONS ' SITE EXPLORATI4N PLAl`, � GEOTECH 2O27 Northeast 21 st Street CONSULTAN'I5,INC. Renton, Washington Job No: Dafe: Plate � 03099 April 2003 No Scale 2 � �ti� ti��`�`� TEST PIT 1 � �o��ti��a�',�ti� G5 ` �e4 Go ,�a �5 Description sM ' Reddish-brown, silty SAND (Topsoil). Gray-brown SAND w/trace of silt, fine- to medium-grained, moist, mediu �-dense. 5 sP 10 * Test Pit was terminated at 10 feet on March 25, 2003. * No groundwater seepage was observed during excavation. * No caving was observed during excavation. 15 � ��,{��i�{ TEST PIT 2 ti^N�o`��ti��a�'roti� G5 �� G° �Sa �5 Description SM � Reddish-brown, silty SAND (Topsoil). ' ' �� Gray-brown, slightly silty SAND w/occasional gravel, roots, and silty san i layers, iSP fine-to medium-grained, moist. II 5 � � Gray SAND wltrace of silt, fine- to medium-grained, moist, medium-den�-a. SP 10 * Test Pit was terminated at 9 feet on March 25, 2003. * No groundwater seepage was observed during excavation. , * No caving was observed during excavation. '� 15 '� TEST PIT LOG I � � GEOTECH 2O27 Northeast 21st Street '' CONSULTANTS,nvc. Renton, Washington i � �� . Job No: Date: Logged by: Plate ; 03099 March 2003 JRF � � �,� ,�<� `i`� TEST PIT 3 ti�`��,��'��J1°��`0�'� G5 . ��,4 Go �a �5 Description ,., Dark brown, organic, silty SAND (Topsoi�). sM , Reddish-brown, silty SAND (Topsoil). i SP Gray-brown, slightly silty SAND w/occasional gravel, roots, and sitty sand layers, s"' fine- to medium-grained, moist. 5 SP ray SAND w/trace of silt, fine-to medium-grained, moist, medium-dense. * Test Pit was terminated at 7 feet on March 25, 2003. 10 * No groundwater seepage was observed during excavation. * No caving was observed during excavation. 15 {� �il TEST PIT 4 � . w� w\ t tir��o`��.ti�fi�a'`�ti� GS �p�� G° �S° �� Description �' •M � Dark brown, organic, silty SAND (Topsoil). ' SM ; ! Reddish-brown, silty SAND (Topsoil). SP Gray-brown SAND w/trace of silt, fine- to medium-grained, moist, mediui i-dense. , 5 * Test Pit was terminated at 4 feet on March 25, 2003. * No groundwater seepage was observed during excavation. * No caving was observed during excavation. 10 15 TEST PIT LOG ,__ � GEOTECH 2O27 Northeast 21st Street coNsuL�i�.�rr-rs,irrc. Renton, Washington � � _ Job No: Date: Logged by: Plate 4 03099 March 2003 JRF � . �,� �,��'�,��`< TEST PIT 5 ��`� o o�,�,�"��`�,�� 5 • ��4 �'G ,�a �5 Description sM Reddish-brown, silty SAND (Topsoil). SP Gray-brown SAND w/trace of silt, fine- to medium-grained, moist, mediuri-dense. '�, 5 ` Test Pit was terminated at 4 feet on March 25, 2003. I ' No groundwater seepage was observed during excavation. * No caving was observed during excavation. 10 15 �l �t� `,�� TEST PIT 6 ��tir��o o�,e��e�a,��e ��5 p G �C � Descnptzon Brown, silty SAND, moist, loose (FILL). i. SM , Brown-gray, silty SAND, fine-to medium-grained, moist, medium-dense 5 snn * Test Pit was terminated at 6 feet on March 25, 2003. * No groundwater seepage was observed during excavation. 10 * No caving was observed during excavation. 15 TEST PIT LOG � � GEOTECH 2O27 Northeast 21st Street CONSULTANTS,r�vc. Renton, Washington � �, � _ ._. Job No: Date: Logged by: PIatE • 03099 March 2003 JRF � . . •---•-•---._._._.__�._.__ ` - - Min.='18�� Undisturbed Native Soil � � � (See Note 4) � Height � � E� Max.=6 feet � � � � or z � Minimum 12-inch width of 2"-4' quarry � � spalls adjacent to rockery. � � s � � � � L�Stable cut face � � � � � � � � 4-inch perforated PVC pipe with ht�es tumed B = (H)�3�� downward slo e to drain to a roe ed outfall ' (min.) � � � P PP ) Min.=12" � � ..__.�_._._.__._._._._._. � � Firm, undisturbed soil GENERAL NOTES: 1) Rock shall be sound and have minimum density of 160 pounds per cubic foot. 2) The bottom row of rocks shall be at least 3-man size. 3) The long dimension of all rocks shall be placed perpendicular to the wall. Each rock should bear on tv o rocks in the tier below. 4) Rockeries are erosion-control structures, not retaining walls. The on-site material must be stable and free-standing in the cut face. Geogrid-reinforced rockeries must be used where they will be subjected to vehicle surcharges. �'° ��'u' ' .�� 0� !�?t1 t,�f.�.� . 5) No roadways or parking shall be located within a 1:1 (Horizontal:Vertical) �' �`�' •, ��;� �f zone of the rockery's base. Footings or structures shall not bear within a '�� rc '�' 2:1 (H:V}zone of the rockery's base. :� )C. - :: �� 6) Any deviation in desig� or in placement of adjacent structures must � ��, �J � be reviewed by the geotechnical engineer of record. o� ��'C1sT�',�'�� .� �' . �'SSfoI�Tl�1e�'��` ' � 3/31��3 EXPIRES �o r��o:� , TYPICAL ROCKERY DETAIt. � GEOTECH 2O27 Northeast 21st Street CONSULTAN'I'S, INC. � Renton, Washington � - - .. __. Job No: Date: PJate:� 03099 March 2003 6 * .' r Slope backfill away from foundation. Provide surface drains where necessary. Tightline Roof Drain (Do not connect to footing drain) Backfill � (See text for � �� requirements) e o ir _� � Vapor Retar..ier Nonwoven Geotextile � or Barrier � Filter Fabric � � Washed Rock " SLAB (7/8" min. size) "--- n C .G.� .p .G,' .�; ,.�. . . , , _ r. . .. . � � �-��- - : e�c c�L ��noC n� . � .. . , . _ � - n°n°n °n= , c,' , "c`'�o o�-c- . . . �� —..�. °n°�� n°n� . ' , �� _— '�I C o- ' n �Q�O� O�CL ii; i -I 6 min. o , _ __. Free-Draining C ravel (if appropriate 4" Perforated Hard PVC Pipe (Invert at least 6 inches below slab or crawl space. Slope to drain to appropriate outfall. Place holes downward.) NOTES: (1) In crawl spaces, provide an outlet drain to prevent buildup of water that bypasses the perimeter footing drains. (2) Refer to report text for additional drainage and waterproofing considerations. TYPICAL FOOTING DR� IN � GEOTECH 2O27 Northeast 21st Streei CONSULTANI'S, �rrc. Renton, Washington � Job No: Date: ca e: Platc :� �- 03099 March 2003 Not to Scale i - 14 ♦ X. BOND QUANTITIES WORKSHEET Zr I . �` 15 XI. MAINTENANCE and OPERATIONS MANUAL I ZZ