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HomeMy WebLinkAbout03253 - Technical Information Report C,j' —�01�•�� �� Core Design,lnc. �'n CORE 14711 N E 29th Place Sui�e #101 �` � D E S I G N Be��ewe,Washing►on 98007 (� 425.885.7877 Fax 425.885.7963 "1 TECI�NICAL I�tFORMATION REPOIZT FOR AVIBER LANE RENTON, WASHINGTOV n.�'\�� '�� � S � �I N� 4 w"s1� � �'o � � 3�A�� .ti ;Y`4I4j�'pT-Y.�- �XPIAEs i 2/14i ;,.�.�_--_ RECEIV '� '� Fr;; -� Prepared by: James A. Nlorin, P.E. Project l��Ianager: David E. Ca}�ton, PE Date: Fe'bruar� 2005 Core No.: 02087 ''•':=�' ' "' ��NGINEERING PLANNING SURVEYING ANTBER LANE TABLE OF CO\TENTS I. Project Overvie�v II. Conditions and Requirements IIL Off-Site Analvsis IV. Flow Control/Water Quality Facility Analysis & Design A. Hydraulic Analysis B. Existing Conditions C. Developed Conditions D. Detention Routing Calculations E. Water Quality Volume V. Conveyance System Analysis and Design VI. Special Reports and Studies VII. Other Permits VIII. ESC Analysis and Design IX. Operations and Maintenance l�lanual ��.��:� � ��� '�� L PROJECT OVERVIE`V Amber Lane is located approximately 200' south of NE 4`h Street and�vest of the unopened Lyon Avenue NE. See Figure 1, Vicinity Map. The 1.12-acre property is currently vacant with ground cover consisting of trees and landscaping. A small wetland is located near the southeast portion of the property. An existing ditch conveys upstream ' and captured onsite drainage from north to south through the property. The developer � proposes to construct 5 single-family residences with associated private roadway and ,i utilities on the 1.12 acre property. A 36-inch conveyance system will be installed to I , convey the existing ditch drainage through the site to the south. The on-site generated runoff will be conveyed to a wetvault located next to the north property line and centrally east-west within the site. From the wetvault, the drainage will discharge into the proposed 36-inch drainage bypass tight-lined system. Some roof leader runoff will be ' directed to the wetland to maintain the���etland hydrology. ' Footing drains for lots 3 and 4 will be tightlined directly to a storm structure that is downstream of the proposed vault outfall. This is because the footings will be lower then � the maximum water surface of the vault and this clean water will only be a minor amount leaving the site. {' ��t� l� 40� I� 4 3 � �w z 55N�`S ��' N.��1S�`� 9�G 900 � � � � � �¢�' 10 8 9 W 11 fA , R E N T 0 N � a� � �!N � ^ �f� �T. ..• NE an� sT. i �� ia�z ; S�. = Z eu P�. N�� ,., � 21C3 � GREENW'OOG i � ` CEY�ETERY o "' � � J 1 7 159 1 6 15 STREET� ' �� I 4 t CEDAR � ���Y � RO a �AA�LEW�OD � � GOLF CGURSE rn �° I//C/N/TYMAP r N N �" - 3ooO� N J � �� rTTT1�E � � � , N C � O �7 O =O �� -a o? o.- N � O � V � � N � V � � � II. CONDITIONS AND REQUIRENIENTS There are no known conditions or special requirements for the property. There is a small wetland, onsite, that has been flagged and inventoried by Alder NW on March 19,2003. The property does NOT include any flood, coal mine, erosion, landslide or seismic hazard areas. The ro ert is located in the Cedar-Sammamish WRIA basin number 8. I P P _Y � � �� i i�.� . � � i Map Output Page 1 of 2 � ��''� Kin� �c�t��tY � � � �'u�� � iMAP - Pro e Information Plannin I !1?'t_Irl�ri} l€ _ .�A:':i ��•) :�'.��._ _ �'i•t.j:.�, '� ... .,_.,,..' �. .i .� . ' .• j�{:- �Itl��-.� . . .. _. . 't.�.. � - .. .. .. . . ' . _,._ . .�._ ..... . I� : . ..- �� . : �. �. . �' � '�. ._.'". _"'_.._.. . ... . , . .11 . ,._. . ._..,..._._,..�__--- . . . . �� � . , i , j � ._.__._. - - : . ,, . ... Q. __..-_ , , ,_ n n�er�cFaa�§ ' 'ss��lc��z�n z 5s3 0£�t;l�:1..'�2f r • Q SC+3t:�.1J250 _ .'_r_ 98t?13�Y�12 S63I1r}ri t i�56+ �.�+�_� :id�t 1:KJ02C1 ; J . .. '; 5fi�<ftC�'�.^: 5E3t70U1fi _.�.,,� NB ' ; - �--- oaar*_�_�_� . �s � Tt- . _ �,.: ��{,(:'!fVlfl�q # �`� '`r f�� � . ( � .. 5631'3i1P230 563�1.U'r: . �- °v6� -'?t7���0 56.f�2«:1t4'1 Ct{;.{:?JL�n1�r �JHdI7(Xk173 , . , , ,, -_ . : _ _ _.�..�� _ r _... ..�_��___�------ __:�7�?6�i :i53!?U/;: tJ8Xtf8L�5�xJ ��';,�;�{?i �. t!�tIB�XJ;�J ;t8%R4t1�0 � � � �s xu:;r;� i ._, ;/BIH��SbE� ;�Bt�J�L�:i� 1"ffl89t`�'= : : fPBIBAiignn �.� _ - — - �` 7/S/$5�Q£3C�IT8789t;," _._ �J:-�tii _�t_r_' _+_�_: . I�'F!?8J'J`_�?J`�fit '76Jg `�J10 �tg789DU:3G� �' . 17818y(YJ1U ' .. . . r:�;�„��;+•� _'C �J'�'_- r. E II81tlEKZC�B�� �� �;3gttqgty _ . �k ' tiylEl9UJIC� tIM7E�9t�L�:,- � F��.� .� Ir�ld9o�i6[1 r;8'gy�.r�� ;�t+rtf4�+_ei�� __ j ��,�,,.;., � , '�.tTBIS�1L�iiQ' .. _ tYB.Ru�i.(!�� :!��gu'�q�n . -_ .. .. � . . • � ..�,�,i /T$;H4YJi1-� _�,i.i�y,i ,.��ji.{.t..i -o���.i -:_.,�,�_� � . _-__ ��,;,,�.� .v .�.��.r::���, {CJ 2UD�King Couniy 0 O.U4B�nl � _ L�gen� 1 _+ :nu:�;y 6r��•idz3-y Zn�i��.� v:; v: a,:� rrxl�.r.. ,�.,, 51tt14�1S A l�l -1�.r:t,�r��.:xi-1J:K.-�. � '��rm:r�-;9�::�r.�:. '�`� .�.�.. a y�rs.,;, _.. A t5 :0.g-t����o.n�x�J 7e�35 x�.�; . '����3cg rii ::J: ���.:.. A�e-a: .. , -o.� � �J C�sc: .� _tr� ?� ti�c:i a-t-id�s-�.� j F�'t?�t P'tYjtl���n DSlt�ct :i�2's-�r�P:ea vw.".v x _w,� rt� � Snund�ry� - 3/s 5 �.�s A�w.a-�J�:x:r,x c-: I'1�7'���"�13•:1 ri-:�:7 �; �gr�utiura!Pr�€i�ct�an D�Y-4.1 a�u� Zr::,��.��._���r_� ��:x:�-. B�i1�1d'2ry �R J-`aYi7�:+=r+c.a��e�aaw•�;f:�.r. � L'fian^uro°,n�lh A�aa L=�� � t 3c•s=r.� •s�c��r= x h :: ��.de-n.:� s 3 J�e� r.r. Lakeaa=id�arga Fc�,�r� �- �" 4t�d±-r:.i a�J 1r�,v:c 51F9�rtt5 4<� �cF d�r.t < �J x:::r.s � #1,�c�esh�a�t Tnbe 712-3 �_r:,t.t2�-J:�a-�e Kan�Gounty Qw�sd;s�openNs � _�f �t:S z_ d:.,�-t.a.ia_:J so�.,ic-e P8�i.Q s - �2= �e=..J�t:f Fc-:J ae''K�s Z7't=.��]L.�09"3 P�7 t i 3,_:i 2�..;.��v i._ v.J�.�r�.�_�.. t�' ,.,i he information included on this map has been compiled by King County staff from a variety of sources and is subject to change without notice. King County makes no representations or warranties.express or implied,as to accuracy,compieteness,timeliness,or rights to the use of such �11T}�:i��\����\l'� llltl!"OkC.�?O�'':�I`1"�ef'C011l.tSl"i �'���,l�i1113}���.SI']Ill�l}����`i<<T'��iCP�1��3111�_-�!�c'r� Ie�v,�C'llc?;... 1 '.''?�In�. IIL OFFSITE ANALYSIS The site is located in the Lower Cedar River drainage basin and the Cedar River/ Lake Washington watershed. Upstream Tributar��Area A drainage ditch collects drainage from a 36-inch storm pipe to the north of the site. The drainage ditch will be tight-lined through the site and will not mix with any of the unmitigated developed drainage. The site only receives a minor amount of runoff from a few adjoining back yards. Downstream Analysis -- Developed mitigated drainage will be discharged to the proposed drainage tight-lined system that will be installed to convey the existing ditch drainage that crosses the site. The existing ditch discharges south and is intercepted by the tight-lined drainage system that is part of the Sienna development to the south. Refer to the Sienna development drainage plans and storm drainage report for the do��nstream drainage route. r�:��,�� � �,,� �,� � IV. FLOW CONTROL /WATER QUALITY FACILITY ANALYSIS & DESIGN ', �. H�-draulic Analvsis The drainage analysis���as modeled usin� the KinQ Countv Runoff Time Series software. The onsite and upstream soils are Alderwood (AgB, AgC), KCRTS group Till. See soils map on the following pages. The site is located in the Sea-Tac rainfall region with a location scale factor of 1.0. B. Esisting Conditions T'he site is 1.01 acres. The property is currently vacant with ground cover consisting of trees and landscaping. The following information was used for generating time series and flo�v frequencies. EXISTII�G CONDITIONS Total Area= 1.08 acres (PREDEV.ts� GROIJND COVER AREA(acre) Till-Forest 1.08 I C. Developed Conditions The developed site will consist of� single-family residences ���ith associated private roadwav and utilities. The impervious area was calculated usin�the criteria in the 1998 King County Surface Water Design Manual page 3-27 and K.C.C.21A.12.030. The proposed development is urban residential. The site is R-5 zoning. The maximum impervious surface per lot was interpolated to be 63%. It was assumed that the Access�'Utility Tract C would be completely impervious. The a�rerage lot size is 7,478 SF per the Preliminary Plat. The average maximum impervious surface per lot is therefore 7,478 SF*63% = 4,711 SF > 4,000 SF � USE 4,000 SF Impervious Area Delineation Onsite private road 6,373 sf Impen�ious area of lots (5 lots*4000sf/lot) 20,000 sf � Total impervious area 26,373 (0.61 acre) The� input used for the KCRTS analysis is suintnarized in the table belo��-: DEVELOPED CONDITIONS Total Area=0.94 acres ' (DEV.ts� GROU\D COVER AREA (acre) Till-Grass (Landscaping) 0.33 Impen�ious 0.61 ��.� . � The site ��-ill have 0.14 Acres of backyard bypass area. A timeseries was created for this area and added to the vault outfall timeseries (rdout.tsfl to produce a final, site release timeseries (site.tsfl. BYPASS AREA Total Area=0.14 acres (BY.ts� GROLT�'D COVER AREA (acre) Till-Grass (Landscaping) 0.14 Impervious 0.00 It is this final site release timeseries (SITE.ts fl that was compared again the predeveloped timeseries (PREDEV.ts� far compliance with the King County Level II standard for frequency and duration. Duration Comparison Anaylsis Base File: predev.tsf New File: site.tsf Cutoff Units: Discharge in CFS -----Fraction of Time----- ------Chec'{ of Tolerance------- Cutoff Base New �Change Probability Base New �Change 0.031 I 0.29E-02 0.31E-02 4.4 I 0.29E-02 0.031 0.032 3.3 0.034 ' 0.25E-02 0.27E-02 9.9 � 0.25E-02 0.034 0.035 3.9 0.037 0.20E-02 0.22E-02 8.2 � 0.20E-02 0.037 0.038 2.5 0.040 0.15E-02 0.17E-02 15.7 I 0.15E-02 0.040 0.042 4.8 0.043 0.11E-02 0.14E-02 21.7 ( 0.11E-02 0.043 0.045 6.6 0.046 0.82E-03 0.11E-02 36.0 � 0.82E-03 0.046 0.049 8.0 0.049 i 0.54E-03 0.91E-03 69.7 � 0.54E-03 0.049 0.051 4.3 0.051 '', 0.36E-03 0.44E-03 22.7 � 0.36E-03 0.051 0.053 2.0 0.054 �� 0.26E-03 0.28E-03 6.3 ( 0.26E-03 0.054 0.056 2.2 0.057 I 0.18E-03 0.21E-03 18.2 � 0.18E-03 0.057 0.059 2.6 0.060 I 0.15E-03 0.82E-04 -44.4 � "0.15E-03 0.060 0.059 -2.3 0.063 I 0.13E-03 O.00E+00 -100.0 � 0.13E-03 0.063 0.059 -6.0 0.066 I, 0.33E-04 O.DOE+00 -100.0 I 0.33E-04 0.0�6 0.051 -7.1 Maximum positive excursion = 0.004 cfs ( 10.0°s) ok occuring at 0.044 cfs on the Base Data:predev.tsf and at 0.049 cfs on the New Data:site.tsf Maximum negative excursion = 0.006 cfs ( -8.5�; occuring at 0.067 cfs on the Base �ata:prede�..ts= and ut C . 051 c�s cn rh? Neo� �uta:site.tsr I':!_�� �( I� D. Detention Routing Calculations Per the Pre-Application Review Comments from the City of Renton, the detention facility will be designed with Level 2 Flow Control. The detention/water quality facility will be a combination water quality and detention wetvault. The wetvault (02087vt.rdfl was sized based on the 1998 KCSV�'DM and KCRTS Computer Software Reference Manual. See attached KCRTS printouts. The wetvault �vill have a minimum surface area of 3,100 square feet and a live depth of 4 feet. The detention routing calculation, a continuation of the hydraulic analysis, uses KCRTS to match the pre-developed outflow to the developed outflow by providing a site-specific amount of detention. The following printout shows a vault 50' wide by 62' long and 4' deep (12,400c� in conjunction with the documented control structure will provide enough live storage (detention) to satisfy this requirement. The actual vault, on the plans, is 50' x 64' x 4' which is 12,800 cf provided. This equates to a 3% safety factor for the loss in volume from constniction inaccuracie�s and the internal ���alls thicknesses. �; „� �,� E. Water Quality Volume Calculations Based on the location of the site, "Basic Water Quality Treatment" is required as shown ��� on the King County Water Quality�Iap on the following page. The dead storage portion of the vault will satisfy this requirement. The required volume of dead storage will be designed per KCSWDM Section 6.4.1.1. The following variables were used in the calculation: Volume Factor(� = 3 ' Rainfall = 0.039 feet or 0.47 inches Area= developed basin Where A; = area of impervious surface (s fl A�g= area of till soil covered with grass (s� Atf= area of till soil covered with forest(s fl Ao = area of outwash soil covered with grass or forest (s fl Vh = 3[0.9A; + 0.?SA�Q = O.IA�;+ O.OlA�,] 1 (R:`12) Vl,= 3[(0.9)(0.61) + (0.25)(0.33) + (0.01)(0.00)]0.039 x (�3560sf'ac)= �,218 CF � The inflo��- and outflow points for the��atilt are both on the south side of the structure. , Therefore a full depth dividing wall is proposed, down the middle of the vault separating it into two boxes 25' x 64' long. These two boxes are connected, hydraulically, by way of a 20-foot wide opening at the north end. This provides a full flow-through design ��hich produces a length to width ratio of 5.1:1 (64x2 /25). Since the 1992 KCSWDM requires a minimum depth of dead storage of 3 feet plus 9-inches for sediment storage, o�Ily a portion of the wetvault�vill be used for dead storage. The remaining area of the �vetvault will accommodate live storage only with an additional 0.5' depth for sediment storage. The first cell is 4-feet deep and the 2"d cell is 3-feet deep, excludin� sediment stora�e. I';�_�� lii ��f l,� The total amount of dead storage provided then, excluding the sediment storage is: (25' x 64' x 4') + (2S x 64' x 3')= 6400 + 4800 = 11,200 cf provided which is much greater then the 3218 cf required. � � � � � i, ,—,, i�:� � „i �:� � � � z � o � N � � z� ,�,� p � ao W � � Wz � � z zo � � � a � � � � �� o � � $ z w � , n `� F P' � o� a � -„ z ' m`h °° � � o ..:–� . . .. • .. . F , o . , , � . . .... . � , , . �jy . 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C'ORENO. 02087 ' ( � � ��? � '' 6.4.1 WETPONDS—BASIC AND LARGE—ME7NODS OF ANALYSIS FIGURE 6.4.1.A PRECIPITATION FOR 1VIEAN ANNUAL STORM IN INCHFS(FEET� S�T 1.0/ ST 1.1 =. ST 1.0 . •2 . 0.8 LA. 0.9 � 1 0 � ��� =� '� _:' � _ � � ...� ,,,,.. , -� ;�.., �, � -�, ��--•--.,,. s t x', `' � i• �;.:; t.' � '_'� —i.,��. �'�i ,_�1.�;�;- - � ��� � ��C --: �'�.�' t . , ,j� P:.¢ ���r ��'. i'�ie�} . i' :� �..^ l. ' � .. 7� �� Sa�L b�1� �..)e.�-� � \ js � ,,.,� ; i I r � :�r—_ . _ �" � - �/ q � _� �`♦ �' . �.:_`� F d � f r1il.�"['l �� I.�`� p s'�f tr � ` ' \ '� � s�L ,{ T, '� '=1.<' s�/ Y�`A�,_ - I� � •'.��! J� I . . :� �-y�'j,�'iX` �" .�. '' \� '� e . ..��C�. —}��,� :� �4 ���-!�` � � tlllott �� � -y� .. - ♦ �� �� �.� ~ :.�- �. � l-'"_ � '� t �i:_:^ /' � i+ _ ^ i i\ � � ' • \_ 1'- . '�s � . _ _ . '�— J �.,- ��� � 't� S.� . � � \ ��''� i . ° �: �-�-... .y �j, \���/_ � ��1 �\ ,�� :y t� ;`,- � �, � ,r ;�-�-� - �^' . / � ��\ .,L LY ,� . k- � - �-, R� a - 4�-� ,�k {.: .. fL � �' � `'� r ,`J\ ,^` �e '\•i�. .� .� r� i _ / •,t , ��:-�, i_ . :� � I r' i -'3 i! � \`—l ..-_.x J! � _- s". _ / .'r . . 1 s�� j I(/ S Y\: �, .: O -\�„��` � � �. a ; f �� a "� i D .. ; F- �� '��� ,�.. .c u..��� { '",J � �T:r�, � r __;.. �. '�,'.`�. _ �,,,�^i e=�i � j '. �� Q . . ` . ,: ;•:<-, , � , � i`� � ..c � 0 ..� . . , j � j �.� _� o ° _ - `� ,s` �• �'�,__-__ _�. . a? i' �,,;� , ;�� y �; �=- ' �" �:': ,— `- Q L.. ,`/ � � o �� � �� �� :^ ��^ l'� -- `i,;f��;y �i�'"'.�\ � 0.54" � '��P,� ���-_�r ' -� , � _ (D.045' ) '.f,/� o' �=��`�r'� _- -�� 6 ;...... ' ; t-��.` o:<o,;.�; �—. ; ....s. �o�.,r �•� 0.47' '�, (0.039') � C • �i`�. '-`� Incorporated Area r; �—�'� ..c� RivedLake 0.47" '� � ,ti �, — Major Road (0.03 9' ) 0.52` �-.\�--� � (0.043'1 0.65" � NOTE:Areas east of the eastemmost isopiwial should use 0.65 0.5 6" (0,0 S 4' ) inches unless rainfall data is available for the location of interest (0.04 7' ) �The mean annual storm is a conceptual stortn found by dividmg the aruwal precipitation by the total number of storm evems per year result,generates large amounts of runoff. For this application, till soil types include Buckley and bedrock soils,and alluvial and outwash soils that have a seasonally high water table or are underlain at a shallow depth(less than 5 feet)by glacial rill. U.S. Soil Conservation Service(SCS)hydrologic soil gr�ups that are classified as till soils include a few B,most C, and all D soils. See Chapter 3 for classification of spec�c SCS soil types. 1998 Surface Water Design Manual 9!1/98 ,6-69 21 A.12.030 A. Densitiss and dimensions - residential zones RESIDENTlAL Z nuwu. uxaw uRe�w 0 M �1/E RES1DBi71Al ��. E S STANDARDS RA-2.5 RA3 RA-10 RA-20 UR R-1 R1 R-fi R-6 A-12 &18 R-24 p.�8� � �� (17) BwDwisky: 02 02 0.! �OAS 02 1 , 4 6 8 �2 7� 24 IE ��, Dw�Yinp dulac dWae dulae dWae OWac dW�e duhe dWac duhc dWae duhe duhe duhc .. ' UNtl/1�a� (21) (� �� (� ��� 0.� OA i 9 12 1t 27 �6 72 �',, . DwM1Yq UnitlAen dufa� tlulac Autae dufac tlufae Aufac duiac dWac dnlae i ��� {ml Ro1 1�1 WYmum DMWhr t57G LS7G 65% �OX TSX 70X iSY. I��, � N� l�� f��l 1�8) I�a► t�al (�a1 i r� nn c+e� (23) YNYmum Lot 1S6 ft 135 R 1]S 1T y75 h 36!t 36 h 30 tt 90 R 30 tt JO R �Mt 30 E 30}t � m m rn �_� �°"r°1°'�"i aat� wrt wn wn ma 2on �on �ote �ox �art �oa �on �ox S'm"k t� �� m r�n m m ro� cn �i rn ro► �� ca� �� Ylnlmum I�ior S R tOft 101! '10 R 5 h 5 R 5 E S lt 5 E S R 5 R i tt 5 tt S�baelc (� (9) � m m m ��� (10) . (10J ('10) ����� Bas�HNpM �0 R ,0 ft �0 R 10!t 35 R 35 R 35 E �S R �S ft 60 R �0 R 60 R W R (4) 16 R �S R �0 tt LO ft i0 R ��� (�� (�4� (��) (�'�� MWmmm � 13X 207L �S% 125X ]07L 30% b9li 70X 73X C5X 15X CS% ' l07L ImP�rvbu+ (91) 1��1 11�) (��) l��) (»I Siahu: S�al 1191 (�',� h�) P«e.ntaa�f�l V C�?�)� =� t� `�, 12-2 (King County 6-00) � --- Predev Comparison ----- Dsout ' - - — __ _ - ------ � _ -.- -- — -- - - --e:e�-� � � i ,� � '' i —�-es -- - — � - ------ -,----- - - �`.`r.�. �----- ---- . � ; � � � � � , i � --- ;. _��t___ _ __ . _. ._'. 0.05 �il �`� i � � I � � --- - _ _ _-�- -_ __ � __ --- -�-04 I j , ' � � � ; N � � � , � v i � � � � � - - -- -� � OA3 (� - ----- ' -_ ---- � � I ; � , i I � � � , ; _.._--- --;--- __--- -�-_ ----�:6� I i � j � , � � � , _ . _ _ _ ___.._.. . .- --- -_. ---__;._-__ 0.01 � � 1 .00 E-05 1 .00 E-04 1 .00 E-�3 1 .00 E-02 1 .00 E-01 Probability Exceedence V. CON�'EYANCE SYSTEI��Z ANALYSIS AND DESIGN Onsite Conveyance The 100-year, undetained runoff from the site is only 0.36 cfs�vhich is well below the 3.4 cfs capacity of a 12-inch pipe at 0.50%. No further calculations are required to confirm , that the 12-inch pipe has adequate capacity for this project. 36-inch Bypass Conveyance The existing pipe entering the site from the north is in a 36-inch pipe and the conveyance pipe leaving the site is also 36-inch. Since this project is proposing to fill in the existing ditch and tie the existing 36-inch on both ends of the project site then no detailed c�om�eyance are nee�ded to confirm the capacity of the selected pipe. i� i _ �,i� ��� i �' i VI. SPECIAL REPORTS AND STUDIES Geotechnical Engineering Study Proposed Amber Lane Residential Development 5409 NE 4`h ST Renton, WA By: Earth Consultants, Inc. April 15,2004 Wetland Evaluation Bales-Renton Property NE 4`" ST East of Lyons Ave NE Renton, WA By: Alder NW, March 19,2003 I'a���� 1; r,i� 1��' c��.� �� � { ,' „ Alder NW March 19, 2003 Projc�ct No. 012303 ...r. Jay Bales SeaPort Dozing O. Box 3015 __�nton,Washington 98056 Subject: Wetland Evaluation Bales-Rernon Properiy NE 4th Street east of Lyons Ave.NE Renton,Washington ear Mr.Bales As requested we have conducted a wetland evaluation study for the property located near the southwest comer of the rtersection of NE 4th Street and Lyons Avenue in the City of Renton. The location of the property is shown on the �icinity Map (Figure 1). The purpose of this work was to conduct a site evaluation to ide�ify the Iimits of wetland conditions on the property. n conducting our site evaluation, we followed the general procedures for the routine on-site methodology as outlined in the March 1997 Washington State Wetlands Identiftartion and Delineation Manual, prepared by the Washington State �partment of Ecology. This procedure involves analysis of vegetation patterns, soil conditions, and near-surface .�ydrology in inaking a deterrmination of wetland conditions. This methodology is similar to the procedures outlined in the �'orps of Engineers Wetland Delineation Mam�al Technica!Report Y-87-1 (198'n. Jur scope of work included a site visit on March 4, 2003,at wluch time we completed our site evaluation and flagged the limits of the wetland areas on the property. The approximate location of the wetland is illustraled on the Site Map(Figure Z). PROCEDURES Eor the purpose of this study, we used the wetland definition adopted by the Environmental Protection Agency(EPA)and the Army Corps of Engineers (COE)for administering Sacti�404 of the Clean Water Act. According to this definition, wetlands are: Those areas that aze inundated or saturated by surface water or groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of 518 North 59� Street,Seattle,Washington 98103•Phone(206j783-1036 email aldernw�aol.com Mr. Jay Bales darch 19,2003 vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps,marshes,bogs,and similar areas. (33 CFR 323). In Washington State,the Shoreline Management Act and Growth Management Act have amended this definition to exclude some wetland situations by adding the following sentences to the wetland definition: Wetlands do not include those artificial wetlands intentionally created from non-wetland sites, including but not limited to, irrigation and drainage ditches, grass-lined swales, canals, detention facilities, wastewaxer treatment facilities, farm ponds, and landscape amenities, or those wetlands created after July l, 1990,that were intentionally created as a result of the construction of a road, street or Highway. Wetlands may include those artificial wetlands internionally created from non- wetland azeas to mitigate the conversion of wetlands. n accordance with this definition,a given area is designated as jurisdictional wetland if the hydrology results in inundated �r saturated soils during ti�e growing season, hydric soils are present, and the dominant vegetation is hydraphytic. '�elineation procedures are based on diagnostic environmenta.l indicators of wetland vegetation, wetland soils, and I Wetland hydrology. By definition, an area is designated as wetland when there are positive indicators for all three parameters. � listing of plant species has been developed for use in the methodology for delineating wetland areas. This listing assigns plant species to one of five indicator status categories ranging from Obligate wetland species, which almost �lways occur in wetlands, to Upland species, which rarely occur in wetlands. Under norn�al conditions, hydrophytic �egetation is determined to be presern if more than 50 percent of the domina.nt species are in the Obligate (OBL), Facultative Wetland(FACVV),or Facuitative(FAC)indicator categories. Diagnostic indicators of hydric soils are relaxed to soil saiuiation, wlrich leads to anaerobic conditions in the soil. Under these conditions, decomposition of organic material is inhibited and soil minerals are reduced, creating characteristic soil �olors that can be quantified by comparison with Munsell Soil Color Charts. A chroma of one or less in unmottled soils �r a chroma of two or less in mottled soils generally indicates a hydric soil. In addition,soils that are saturated during the growing season satisfy a criterion for hydric soils. We used a hand auger to collect soil samples from a depth of 8 to 16 inches. Wetland hydrology is defined as inundated or saturated soil conditions for at least 14 consecutive days during the growing season. If no water is prese�at the time of evaluation,ather indicaiors may include topographic low points or channels, �lood debris,complete absence of vegetation,or presence of hydric soils. Standardized data forms are available to record observations on each parameter. For this project, we completed data forms for the Routine On-Site Determination Method at 3 locations on the site. Copies of these data forms are included with this report. SITE CONDITIONS The subject property is an irregulazly shaped property composed of three separate tax parcels, with a combined azea of approximately 13 acres. Parcel A of the praperty bas an existing residence wi�address NE 4th Street at 5409 NE 4th Street. Access to NE 4th Street for parcels A and B is through Parcel C as shown on the Site Map (Figure 2). The Project No.0123�3 Page No. 2 ;vir.Jay Bales March 19,2003 �djace�t properties to the south and east aze occupied by residerrtial development currently under construction. Other idjacent properties are occupied by existing single-family residences. Topographically,the property is generally flat with a gradient sloping down from north to south. Soils on the property and over the surrounding area are mapped as Alderwood gravelly sandy loa.m(Soil Survey of King Counry, Washington, U.S. Soil Conservation Service, 1973). Alderwood soils aze described as a moderately well drained soil formed under conifers in glacial deposits. It has a relatively impermeable consolidated substratum at depths of 24 to 40 inches below the surface. This soil type is not included on the National Technical Committee on Hydric Soils listing of hydric soils, ahhough wetland conditions are often found in shallow depressions within Alderwood soil units. Our observations of soil conditions across most of the property aze generally consisteut with the Alderwood soil type,although surface soils across much of the pmperty have been disturbed,attering the topsoil conditions.. Soils across the majority of the properiy are generally brown to dark brown(10YR4/3 to 10YR3/3), observed at depths below the topsoil layer(12"to 16"). Vegetation on the property is generally characterized as grassy with sca.ttered tall trees and patches of shrub growth. The northern section of Pazcels B and C, and the area around the elcisting house on Parcel A has been regularly mowed and includes landscape plantings. The southern section includes mowed grass with shrub growth includiag Himalayan blackberry (Rubus drscolor). Tree species present inclnde red alder (Alm�s rubra), black cottonwood (Populus balsamifera),big leaf maple(Acer macrophyllum),and Douglas fir(Pseudotsuga menzresii)and western red cedar(Thuja plicata). Wetland We have idernified the limits of a wetland which extends across southem property (ine orno Pazcel C. This wetland was idenRified as Wetland A in the Wetland Report for the Sienna residential development prepar�ed by Northwest C'onsuhants, Inc., dated August 7, 2001. We located the flags identifying the weTland limits which were placed by Northwest Biological Consuttants in July, 2001. Our observations were in general agreemeirt with the limits as previously ide�tified for the Sienna project. The wetland location shown on the Site Map (Figure 2) is based on the limits shown on maps prepared for the Sienna projed. The wetland was identified as a City of Renton Category 3 Wetland and was assigned a ZS foot buffer. We also idertified a smatl area of saturated soils to the north of Wetland A. This azea is separated from Wetland A by more than SO feet and has a to�tal area of less than 1,000 sq.ft. As such it is unregulated under City of Reuton regulations. There is an elccavated ditch line crossing the pmperty from north to south. This ditch line originates in a 42"culvert under ! NE 4th Street w}uch outlets o�to pazcel A about 50 south of NE 4th Street. The ditch then runs along the west property line of Pazcel A and then crosses the west side of parcel B. It eirters a recently construded catch basin immediately to the south and drainage is contained in a culvert through the Sienna Project. New construction for the Sienna project included grading to cover the open ditch line and installing a culvert to carry the drainage across the Sienna to a discharge point at SE 132nd Street. A wetland analysis for the Sienna property conducted by B-12 Associates, dated November 6, 2001 addressed the ditch and concluded that it is part of a storm-water system for the area. The ditch line crossing the subject property is part of the same storm-water system and should be treated similarly as it was in the design of the Sierma project. Project No.012303 Page No. 3 Mr_Jay Bales I Vlarch 19,2003 I 4s was done where the ditch line crossed the Sienna project, it would be appropriate to ca.rry the surface water drainage cross the subject property in a covered pipe line for a proposed residential developmeirt. We trust the information presented is sufficient for your current needs. If you have any questions or require additional information,please call. Sincerely yours, ALDER NW �� �� Garet P. Munger Project Scie�ist Encl.: Data Fom�s (3) Vicinity Map—Figure 1 Site Map—Figure 2 Project No. 012303 Page No. 4 DATA FORM ROUTINE ON-SITE WETLAND DETERMINATION Describe General Site Site is within urban surrounding. Site cleared Data Point No.: DP-1 Conditions: with lawn and scattered trees and shrubs. Site Disturbance? N'estern red cedar tree recently fell across area. I.ocation: North of wetlarrd A VEGETATION o �, o � Dominant Plant Species � � � Dominant Plant Species � � � � � �� � �� � 1 Rubus discolor FacU- S $ 2 Urtica dioica Fac+ H 9 3 Ranunculus repens FacW H 10 4 Acer macrophyllum FacU T 11 5 12 6 13 7 14 Percent of dominant species that are OBL,FACW,and/or FAC: 8� Is the hydroph}�tic vegetation criterian met? Yes Rationale: More than SO'�species hydrophytic SOIL ' Soil Type: Alderwood Hydric Soils List: No Histic Epipadon? No Mottles? No Gleyed? No , Matrix Color. 2.SY3/3 Mott1e Colors: - Uepth: 12" Other hydric soil indicators: No Is the hydric soil criterion met? No Rationale: Chroma greater than 2 HYDROLOGY Is the ground surface inundated? No Surface water depth: - Is the soil saturated? Not in upper 12" Depth to free-standing water in probe hole: 1 q" Other field evidence hydrology: No Is the wetland hydrology criterion met? No Rationale: No evidence of lorrg term saturation WETLAND DETERMINATION Are wetland criteria met? No Rationale for wetland decision: Non hydric soil; no evidence of long term saturation. Project Name: Bales Rerrton Property AlderrjW Field Investigator(s): G.Munger 518 North 59th Street Project No.: 012303 Date: 3/4/03 Seattle,Washington 98103 DATA FORM ROUTINE ON-SITE WETLAND DETERMINATION Describe General Site Site is within urban sunounding. Site cleared Data Poi�No.: DP-2 Conditions: with lawn and scattered trees cmd shrubs. Site Disturbance? Location: See site Map VEGETATION ' 0 0 �, i Dominant Plazrt Species � � � Dominant Plant Species � � � i, � � � � 2 Ranuncu/us repens FacW H S 2 Populus balsamifera Fac T 9 3 Grasses H 10 4 Juncus effusus FacW H 11 5 12 6 13 7 14 Percent of dominant species that a.re OBL, FACW,and/or FAC: 1�a Is the hydrophytic vegetation criterion met? Yes �tjp�e; More than SO'�species hydrophytic SOIL Soil Type: Alderwood Hydric Soils List: No Histic Epipedon? No Mottles? No Gleyed? No Matrix Color: IOYR4/3 Mo�tle Colors: - Depth: IZ" och�nyar;�������: No Is the hydric soil criterion met? No Rationale: Chroma greater rhan 2 HYDROLOGY Is the ground surfice inundated? No Surface water depth: - IS the soil saturated? Not in upper 12" Depth to free-standing water in probe hole: - Other field evidence hydrology: No Is the wetland hydrology criterion met? No Ratipnale: No evidence ojlong term soil saturation WETLAND DETERMINATION Are wetland criteria met? No Rationale for w�land decision: Non hydric soil; no evidence of long term soil saturatron Projed Name: Bales Renton Property A1derNW Field Investigator(s): G.Munger 518 North 59th Street Project No.: 012303 Date: 3/4/03 SeatEle,Washingtan 98103 DATA FORM ROUTINE ON-SITE WETLAND DETERMINATION Describe General Site Site is within urban surrounding. Site cleared Data Point No.: DP-3 Conditions: with lawn and scattered trees and shrubs. Site Disturbance? I,ocation: See site Map VEGETATION 0 � ., � Dominant Plant Species � � � Dominant Plant Species o � � �� � � � � 1 Rurrunculus repens Fac H $ 2 Jurrcus efjusus Fac H 9 3 Populus balsamifera Fac T 10 4 11 5 12 6 13 7 14 Perc.ent of dominant species that are OBL,FACW, and/or FAC: 100 Is the hydrophytic vegeta.tion criterion met? Yes Rationale: More than SO%species hydrophytic SOIL Soil Type: Alderwood Hydric Soils List: No Histic Epipedon? No Mottles? No Gleyed? no Matrix Color. IOYR2/1 Mottle Colors: - Depth: 12" Other hydric soil indicators: No Is the hydric soil criterion met? Yes Rationale: Chroma 1 HYDROLOGY Is the ground surface inundated? No Surface water depth: - Is the soil saturated? Yes Depth to fi-ee-standing water in probe hole: 4" Other field evidence hydrology: No Is the wetland hydrology criterion met? Yes Ratipnale: Wafer level in upper 12" WETLAND DETERMINATION Are wetland criteria met? Yes ', Rationale for wetland decision: Positive indicators for each parameter. This is small isolated area less than IS00 sq;ft. ', Project Name: Bales Renton Propertv A1derNW II Field Investigator(s): G.Munger 518 North 59th Street Project No.: 012303 Date: 3/4/03 Seattle,Washington 98103 �'J.�. 4TN ST. (S.E. 128TH ST.;� � I � � � �, Q ` .. � J � W K .�- � a � a ' W � Z � GP-1 Approximate Data °oint _ocetion ICARPOkT � � 1 � � "' ' � U i X HWSE � U sr+E x— — ____ � 6;CLF X—4-��X___.--� I � I i .v c� �� ' m �'� w � C � � � �`L v o ; Q • Q � � Q a o a � � 1 0 J � • pP' � o � E � o ; � °�f Q� ` --, � ___� i ,�� � P �� , c� � '�l 28"FIR � ����,���/� f� � , ` I(n � ° � � � 8 5' DIA. CONC. � , �� w , \ } 4�= �W STRUCIURE U � w a � ` �• Q W/TRASH RACK �v � ` � 4.55' CEEP ' � � � i a i/7 �S`ierzna � a z 0 � APPROXIMATE SCALE � 50 0 5Q 100 feet SITE MAP A L D E R N IN Ba�es—Renton Property Renton, Wa. roject No.012303 Date Man�,, zoo3 Fgure 2 Jr � � _ :-+ , � _ NE.�t}i sT •.. � _ f,?: � sE_72fTH.3T 5m rN�TTH PL � � ' . , . . . � '� ��5 t2tST 3T._ x,;y I � ._ m -` .. ,•� N E�T.7N ST ` �� �.,� ,�;f� � . �`, '� � - - - _ -- r: : - .. ..� . . � �_:�`� h� � . r RlE 6T�.1 �' -x" }s':� � 4� .� ' � o � r' !t6 6T�T . - ! z ��' i �: S r. ��' .� -� i a �i �NE 6TH 3t t�lE 5T H_ST: - � �, gE,34TN ST A{� - _) <_ � _ NESTHST �N��M L � �125TH5? I �` � ,y - i r 2 � 'SE 426?H ST � � `� � � ^�' r S a1�� � 's � g� - � m. . E 411�ST � ��Sf 128TH SJ � _ � i _ - SE 124tN_ST . _ - �f� , = - s � _ _ � .SE 137St T�'"`� 'h-_t.: a � . � •' 4��i � j = SE 132ND sT �' �D ST - •SE 132ND_ST -_ I,;iF . +" SE 13ZND S.T _ I a ,_ , � � � • s �s`sRn ar '"_ - . ._ � . � �,3� , SIE 33Rp_CT ,� - < � I _ . _ _ . �`�_ SE 1ST� .� , �Sf,r1�ITN_i � � SE 135TH 8T SE.,135TN.3 . iy ' ? 4 5E 21�ID-�L.— .� -. ��� . SE 13iT. �? � . . 9E 1�iTH -', {�- � � ` R4�"�f; . - o .. • 4 ��-• . � ci �.t�7T.H.P_l � �.� ; � � � _ i �'�'(V� .- �� �. .- _ � w _ . . . ._ .. , . � 5� P, ,' � �SE t3dTH L _ � ' ��;�- • �� � - i-_ � . -._ r � � � .�'' .�. . , , • ' � � _73l1N.P.L . • . . . . . . . . � ._• _ s�+bt)i. ? ,°� ._- -- _. -. . _ ,. _ . � _ a �.• � - ��Si ST -- �. - S• _ � . - �a - _ _ _. kJ�eot inwa�ouwT+r�; � � � VICINITY MAP Bales—Renton Property ALD E RN W Renton, Washington Project No.012303 Date �arct►, 2003 Figure 1 GEOTECHNICAL ENGINEERING STUDY PROPOSED AMBER LANE RESIDENTIAL DEVELOPMENT 5409 NORTHEAST FOURTH STREET RENTON, WASHINGTON E-11126 Aprii 15 2004 PREPARED FOR SEA-PORT DOZING AND DEVELOPMENT, INC. j T - Steven T. Swenson Staff Geologist � *ti11►RIF .���.pf WAsk���t` "� ,��' � ~O � � �� � Z � �� �j ,4 33182 p �y� �S��� �.�cP}��s az-o�o s- `���s�°`� Kristina M. Weller, P.E. Project Manager Earth Consultants, Inc. 1805 - 136th Place Northeast, Suite 201 Bellevue, Washington 98005 (425) 643-3780 Toll Free 1-888-739-6670 IMPORTANT INFORMATION ABOUT YOUR GEOTECHNICAL ENGINEERING REPORT More construction problems are caused by site subsur- technical engineers who then render an opinion about face conditions than any other factoc As troublesome as overall subsurface conditions, their likely reaction to subsurface problems can be, their frequency and extent proposed construction activity, and appropriate founda- have been lessened considerably in recent years, due in tion design. Even under optimal circumstances actual large measure to programs and publications of ASFE;` conditions may differ from those inferred to exist, The Association of Engineering Firms Practicing in because no geotechnical engineer, no matter how the Geosciences. qualified,and no subsurface exploration program, no The follou�ing suggestions and observations are offered matter how comprehensive, can reveal what is hidden by to hel earth, rock and time The actual interface between mate- p you reduce the geotechnical-related delays, rials may be far more gradual or abrupt than a report cost-overruns and other costly headaches that can indicates. Actual conditions in areas not sampled may occur during a construction project. differ from predictions. Nothing can be done to nrevent the unanticipated, but steps can be taken ta heln minimize their A GEOTECHNICAL ENGINEERING impact. For this reasen, most exnerienced o►uners retain their REPORT IS BASED ON A UNIQUE SET 9Qotechnical consu(tants tHrough the construction stage, to iden- tify variances, conduct additional tests which may be OF PROJECT SPECIFIC FACTORS needed, and to recommend solutions to problems A geotechnical engineering report is based on a subsur- encountered on site. face exploration plan designed to incorporate a unique SUBSURFACE CONDITIONS set of project-specific factors. These typically include: the general nature of the structure involved, its size and CAN CHANGE configuration; the location of the structure on the site and its orientation: physical concomitants such as Subsurface conditions may be modified by constantly- access roads, parking lots, and underground utilities, changing natural forces. Because a geotechnical engi- and the level of additional risk which the dient assumed neering report is based on conditions which existed at , by virtue of limitations imposed upon the exploratory the time of subsurface exploration, construction decisions ! program. To help avoid costly problems, consult the ���nuld not be based on a geotecknical engineering report whose geotechnical engineer to determine how any factors adequacy may have,heen affected by time. Speak with the geo- which change subsequent to the date of the report may technical consultant to learn if additional tests are affect its recommendations. advisable before construction starts. Unless your consulting geotechnical engineer indicates Construction operations at or adjacent to the site and otherwise, your geotec�inical engineering report should not natural events such as floods,earthquakes or ground- be used: water fluctuations may also affect subsurface conditions •When the nature of the proposed structure is and, thus, the continuing adequacy of a geotechnical changed, for example, if an office building will be report. The geotechnical engineer should be kept erected instead of a parking garage,or if a refriger- apprised of any such events,and should be consulted to ated warehouse will be built instead of an unre- determine if additional tests are necessary. frigerated one; •�vhen the size or configuration of the proposed GEOTECHNICAL SERVICES ARE structure is altered: PERFORMED FOR SPECIFIC PURPOSES •when the ]ocation or orientation of the proposed structure is modified; AND PERSONS •when there is a change of ownership, or Geotechnical engineers' reports are prepared to meet •for application to an adjacent site. the specific needs of specific individuals. A report pre- Geotechnical enyineers canKot accept responsibility(or problems �reci for a consuiting civil engineer may not be ade- which may develon i/they are not consufted a(ter factors consid- quate for a construction contractor,or even some other ered in their report's developmeat have chanqed. consulting civil engineer. Unless indicated otherwise, this report was prepared expressly for the client involved and expressly for purposes indicated by the client. Use MOST GEOTECHNICAL "FINDINGS" by any other persons for any purpose, or by the dient ARE PROFESSIONAL ESTIMATES for a different purpose, may result in problems. No indi- vidual other than the client should apply this report Jor its Site exploration identifies actual subsurface conditions intended purpose without�irst con/erring with Ihe geotechnica( only at those points where samples are taken, when engineer. No persnn should apply this report(or any purpose they are taken. Data derived through sampling and sub- other than that originally contemnlated u�ithout hrst conferring sequent laboratory testing are extrapolated by geo- with the geotec(rnical engineer F�rt�� Gons�alt�nts, Inc. (AxHIY��l1lN�i111-Jl�;lll(YYS.(i[(�(�;ISlSXiIJI\'If(Nlill(y1ti11SC'I(7111SIti �Src�A)��5�)f%�� 1�7J (iM1.SII1K'tICHt I(,tiII11j;Rk l(7;();H:�\I3()Illti�l(r'�I(N7 5C'.1'�7("C:ti April 9, 2004 E-11126 Sea-Port Dozing and Development, Inc. P.O. Box 3015 Renton, Washington 98056 Attention: Mr. Robin Bales Dear Mr. Bales: Earth Consultants, Inc. (ECI) is pleased to submit our report titled "Geotechnical Engineering Study, Proposed Amber Lane Residential Development, 5409 Northeast Fourth Street, Renton, Washington". This report presents the results of our field exploration, selective laboratory tests, and engineering analyses. The purpose and ', scope of our study were outlined in our April 5, 2004 proposal. i In general, our study indicates the site is underlain by native medium dense to dense I��, silty sand with varying amounts of gravel. I Based on the results of our study, it is our opinion the site can be developed generally as planned. The proposed single-family residences should be supported on conventional spread and continuous footing foundation systems bearing on competent native soil or on newly placed structural fill used to modify site grades. !� We appreciate this opportunity to be of service to you. If you have any questions, or if I we can be of further assistance, please call. Respectfully submitted, EARTH CONSULTANTS, INC. �___ Scott D. Dinkelman, LEG Associate Principal STS/SDD/KMW/csm 1805136th Place N.E., Suite 201, Bellevue,WA 98005 Bellevue (�2516�3-3780 FAX j425;1 746-0860 Toll Free 1888j i 39-6670 TABLE OF CONTENTS E-11126 PAGE INTRODUCTION................................................................................................ 1 General ....................................................................................................... 1 Scopeof Services ........................................................................................ 1 ProjectDescription ...................................................................................... 2 SITECONDITIONS ............................................................................................ 3 Surface ....................................................................................................... 3 Subsurface .................................................................................................. 3 Groundwater................................................................................................ 4 LaboratoryTesting ....................................................................................... 5 DISCUSSION AND RECOMMENDATIONS ............................................................ 5 General ...................................................................................................... 5 Site Preparation and General Earthwork........................................................... 6 Foundations................................................................................................. 7 Slab-on-Grade Floors..................................................................................... 8 RetainingWalls ............................................................................................ 8 Seismic Design Considerations....................................................................... 9 GroundRupture ....................................................................................... 9 Liquefaction ............................................................................................ 10 Ground Motion Response.......................................................................... 10 ' Excavations and Slopes................................................................................. 10 SiteDrainage ............................................................................................... 1 1 � Utility Support and Backfill ........................................................................... 12 ', PavementAreas ........................................................................................... 13 LIMITATIONS .................................................................................................. 13 AdditionalServices....................................................................................... 14 Earth Co�sultants, Inc. TABLE OF CONTENTS, Continued E-11126 ILLUSTRATIONS Plate 1 Vicinity Map Plate 2 Test Pit Location Plan Plate 3 Retaining Wall Drainage and Backfill Plate 4 Typical Footing Subdrain Detail �I Appendices Appendix A Field Exploration �I Plate A1 Legend � Plates A2 through A5 Test Pit Logs � Appendix 6 Laboratory Test Results , Plate B1 Grain Size Analyses Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY PROPOSED AMBER LANE RESIDENTIAL DEVELOPMENT 5409 NORTHEAST FOURTH STREET RENTON, WASHINGTON E-11126 INTRODUCTION General This report presents the resuits of the geotechnical engineering study completed by Earth Consultants, Inc. (ECI) for the Proposed Amber Lane Residential Development, 5409 Northeast Fourth Street, Renton, Washington. The general location of the site is shown on the Vicinity Map, Plate 1 . The purpose of this study was to explore the subsurface conditions at the site and, based on the conditions encountered, to develop geotechnical recommendations for the proposed single-family residence development. Scope of Services We performed this study in general accordance with the scope of services outlined in our April 5, 2004 proposal. On this basis, our study addresses: • Subsurface soil and groundwater conditions; � Site preparation, grading, and earthwork procedures, including details of fill placement and compaction; • The suitability of using on-site materials for use as structural fill, and providing recommendations for imported fill materials; • Foundation design recommendations, including bearing capacity and lateral pressures for walls and structures; • Utility trench excavation and backfill recommendations; • Seismic design criteria, including an evaluation of potential liquefaction hazard; � Short-term and long-term groundwater management and erosion control measures; Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY ' Sea-Port Dozing and Development, Inc. E-1 1126 April 15, 2004 Page 2 • Potential total and differential settlement magnitudes; and • Temporary slope recommendations. Project Description We understand it is planned to develop the approximately 1 .3-acre, irregularly shaped, ' property with a single-family residence development. Based on preliminary project information provided by the client, the proposed development will include up to five ' single-family residence lots, a stormwater detention tract, a wetland tract, and an arterial roadway extending to Lyons Avenue Northeast. At the time our study was performed, the site and our exploratory locations were approximately as shown on the , Test Pit Location Plan, Plate 2. Based on our experience with similar projects, we anticipate the single-family ', residences will be two stories in height and will be of relatively lightly loaded wood- , frame construction with a combination of slab-on-grade and wood joist floors. Wall ', loads will likely be on the order of 2 to 3 kips per lineal foot, with column loads of 20 I, to 30 kips, and stab-on-grade floor loads of 150 pounds per square foot (psf). � We estimate cuts and fills of five feet or less will be required to reach construction subgrade elevations within the site. The conclusions and recommendations in this study are based on our understanding of the proposed development, which is in turn based on the project information provided us. If the above project description is incorrect or the project information changes, we should be consulted to review the recommendations contained in this study and make modifications, if needed. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Sea-Port Dozing and Devetopment, inc. E-11126 April 15, 2004 Page 3 SITE CONDITIONS Surface The subject site consists of an approximately 1 .3-acre, irregularly shaped, property that includes an existing residential lot located at 5409 Northeast Fourth Street, Renton, Washington. The approximately 1 .1-acre, roughly rectangular, portion of the site to be developed lies immediately south of the existing residential lot. The area to be developed extends roughly seventy-five (75) feet west, two hundred twenty-five (225) feet east, and one hundred sixty-three 1163) feet south of the southwest property corner of the existing residential lot (See Plate 1 , Vicinity Map). The site is bordered to the north by Northeast Fourth Street, to the south by an existing residential development, to the east by single-family residences and Lyons Avenue Northeast, and to the west Chuck's Donut Shop and an existing single-family residence. The site contains an existing single-family residence located in the northern portion of the property and a north-south running drainage located in the western portion of the property. We understand that the existing residence is to remain. The site topography is relatively level with a maximum elevation change on the order of four feet. The site is primarily vegetated with short grass and scattered growths of blackberries. The site is also vegetated with sparse, medium to large diameter pouglas fir, maple, cedar, and cottonwood trees. Subsurface Subsurface conditions at the site were evaluated by excavating four test pits at the approximate locations shown on Plate 2, Test Pit Location Plan. The test pits were excavated to a maximum depth of eleven and one-half (1 1 .5) feet below existing grade. Please refer to the Test Pit Logs, Plates A2 through A5, for a more detailed description of the conditions encountered at each location explored. A description of the field exploration methods is included in Appendix A. The following is a generalized description of the subsurface conditions encountered. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Sea-Port Dozing and Development, Inc. E-11 126 April 15, 2004 Page 4 At our test pit locations, we encountered a surficial layer of topsoil and grass. The topsoil and vegetation layer was typically three to six inches thick but ranged up to one and one-half feet thick as encountered in Test Pit TP-4. The topsoil and vegetation layer was characterized by its dark brown color, loose consistency, and the presence of abundant roots and organic debris. The topsoil and vegetation layer is not considered suitable for support of the proposed foundations. In addition, it is not suitable for use as structural fill, nor should it be mixed with material to be used as structural fill. Underlying the topsoil and grass, we encountered medium dense native soil comprised of silty sand with varying amounts of gravel (Unified Soil Classification SM). The soil became dense at two to four feet below existing grade and remained dense to the maximum depth explored in Test Pits TP-1 through TP-3. In Test Pit TP-4, the dense silty sand (SM) became medium dense at approximately six feet below existing grade. Medium dense poorly graded sand with silt (SP-SM? was encountered from approximately ten and one-half {10.51 feet below grade to the maximum exploration depth of eleven and one-half {11 .5) feet. Groundwater i We encountered moderate to heavy groundwater seepage at our test pit locations at depths ranging from one and one-half (1 .5) to ten and one-half (10.5) feet below existing grade. The observed seepage is likely indicative of seasonal perched groundwater collecting along the contact between the overlying medium dense soils and underlying dense soils encountered at our test pit locations. If earthwork is conducted during the wet season, it is likely moderate to heavy groundwater seepage will be encountered. If seepage is encountered, the contractor should be prepared to address seepage in excavations. Based on observed conditions at the site, groundwater levels at the site will likely fluctuate, depending on the season, amount of rainfall, surface water runoff, and other factors. Generally, the water level is higher and seepage rates are greater in the wetter winter months (typically October through May). Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Sea-Port Dozing and Development, Inc. E-11126 April 15, 2004 Page 5 I� Laboratory Testing Laboratory tests were conducted on representative soil samples to verify or modify the field soil classifications and to evaluate the general physical properties and engineering characteristics of the soil encountered. Visual field classifications were supplemented , by grain size analyses on representative soil samples. Moisture content tests were ', performed on all samples. The results of laboratory tests performed on specific samples are provided either at the appropriate sample depth on the individual test pit , logs or on a separate data sheet contained in Appendix B. It is important to note that these test results may not accurately represent the overall in-situ soil conditions. Our geotechnical recommendations are based on our interpretation of these test results. I' ' ECI cannot be responsible for the interpretation of these data by others. In accordance with our Standard Fee Schedule and General Conditions, the soil , samples for this project will be discarded after a period of fifteen (15) days following completion of this report unless we are otherwise directed in writing. DISCUSSION AND RECOMMENDATIONS General Based on the results of our study, in our opinion, the proposed single-family residences should be supported on conventional spread and continuous footing foundation systems bearing on competent native soil or on newly placed structural fill used to modify site grades. Slab-on-grade floors should be similarly supported. If loose native soil is encountered at construction subgrade elevations, it should be compacted in- place to the requirements of structural fill to a depth of at least twelve (12) inches below the proposed subgrade elevation. This report has been prepared for specific application to this project only and in a manner consistent with that level of care and skill ordinarily exercised by other members of the profession currently practicing under similar conditions in this area for the exclusive use of Sea-Port Dozing and Development, Inc. and their representatives. No warranty, expressed or implied, is made. This report, in its entirety, should be included in the project contract documents for the information of the contractor. Earth Consultanis, Inc. —� GEOTECHNICAL ENGINEERING STUDY Sea-Port Dozing and Development, Inc. E-1 1 126 April 15, 2004 Page 6 Site Preparation and Gene�al Earthwork Building, pavement, and areas to receive structural fill should be stripped and cleared of surface vegetation, organic matter, and other deleterious material. Based on the thickness of the topsoil and vegetative layer encountered at our test pit locations we estimate a stripping depth of approximately three to six inches for the majority of the site with localized areas extending to twelve (12) inches below existing grade. Stripped materials should not be mixed with materials to be used as structural fill. The stripped materials may be wasted on-site in landscaping or yard areas. Following the stripping operation, an ECI representative should observe the ground surface where structural fill, foundations, or slabs are to be placed. Soil in loose or soft areas, if recompacted and still yielding, should be overexcavated and replaced with structural fill. The optional use of a geotextile fabric placed directly on the overexcavated surface may help to bridge unstable areas. ECI can provide recommendations for geotextiles, if necessary. Structural fill is defined as compacted fill placed under buildings, roadways, floor slabs, , pavements, or other load-bearing areas. Structural fill under floor slabs, footings and pavements should be placed in horizontal lifts not exceeding twelve (12) inches in loose thickness and compacted to a minimum of 90 percent of its laboratory maximum dry density determined in accordance with ASTM Test Designation D-1557-91 ' (Modified Proctor). The fill materials should be placed at their optimum moisture I content. The top twelve (12) inches of fill under floor slabs and pavements should be � compacted to 95 percent of maximum dry density. Based on the results of our laborator tests, the on-site soils, at the time of our I Y exploration, appear to be at or above their optimum moisture content and may require moisture conditioning to be suitable for use as structural fill. Laboratory testing indicates the site soils have between 18 and 33 percent fines passing the No. 200 sieve. Soil with fines in excess of 5 percent wi�l degrade if exposed to excessive moisture, and compaction and grading will be difficult if the soil moisture increases significantly above its optimum level. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Sea-Port Dozing and Development, Inc. E-11126 April 15, 2004 Page 7 During dry weather, any non-organic compactable granular soil with a maximum grain size of four inches can be used. Fill for use during wet weather should consist of a well graded granular material having a maximum grain size of four inches and no more than 5 percent fines passing the No. 200 sieve based on the minus 3/4-inch fraction. A contingency in the earthwork budget should be included for this possibility. Foundations Based on the results of our study and provided our recommendations are followed, in our opinion, the proposed single-family residences should be supported on conventional spread and continuous footing foundation systems bearing on competent native soil or on newly placed structural fill used to modify site grades. Exterior foundation elements should be placed at a minimum depth of eighteen (18) inches below final exterior grade. Interior spread foundations should be placed at a minimum depth of twelve (12) inches below the top of slab, except in unheated areas, where interior foundation elements should be founded at a minimum depth of eighteen (18) inches. With foundation support obtained as described, for design, an allowable soil bearing capacity of two thousand five hundred (2,500) psf should be used for competent native soil, native soil compacted in place to the requirements of structural fill, or for newly placed structural fill used to modify site grades. Continuous and individual spread footings should have minimum widths vf sixteen (16) and eighteen (18) inches, respectively. Loading of this magnitude would be provided with a theoretical factor-of- safety in excess of 3.0 against shear failure. For short-term dynamic loading conditions, a one-third increase in the above allowable bearing capacities can be used. With structural loading as expected, and provided the above design criteria are followed, total settlement in the range of one inch is anticipated with differential settlement of about one-half inch. Most of the anticipated settlements should occur during construction as dead loads are applied. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Sea-Port Dozing and Development, Inc. E-1 1126 April 15, 2004 Page 8 Horizontal loads can be resisted by friction between the base of the foundation and the I'�I supporting soil and by passive soil pressure acting on the face of the buried portion of the foundation. For the latter, the foundation must be poured "neat" against the competent native soils or backfilled with structural fill. For frictional capacity, a coefficient of 0.35 should be used. For passive earth pressure, the available resistance should be computed using an equivalent fluid pressure of three hundred fifty (350) pounds per cubic foot (pcf). The lateral resistance value is an allowable value, a factor- of-safety of 1 .5 has been included. As movement of the foundation element is required to mobilize full passive resistance, the passive resistance should be neglected if such movement is not acceptable. Footing excavations should be observed by a representative of ECI, prior to placing ' forms or rebar, to verify that conditions are as anticipated in this report. Slab-on-Grade Floors Slab-on-grade floors should be supported on competent native soil or on structural fill used to modify site grades. Loose or disturbed subgrade soil must either be recompacted or replaced with structural fill. Slabs should be provided with a minimum of four inches of free-draining sand or gravel. A vapor barrier such as a 6-mil plastic membrane should be placed beneath the slab. Two inches of damp sand may be placed over the membrane for protection during construction and to aid in curing of the concrete. Retaining Walls If retaining walls are planned for this project, they should be designed to resist the lateral earth pressures from the retained soils and applicable surcharge loading. Walls that are designed to yield can be designed to resist the laterat earth pressures imposed by an equivalent fluid with a unit weight of thirty-five (35) pcf. If walls are to be restrained at the top from free movement, the equivalent fluid weight should be increased to fifty (50) pcf. These values are based on horizontal backfill conditions. Surcharges due to backfill slopes, hydrostatic pressures, traffic, structural loads or other surcharge loads are assumed to not act on the wall. If such surcharges are to apply, they should be added to the above design lateral pressure. The passive pressure, allowable bearing capacity, and friction coefficient previously provided in the Foundatrons section are applicable to the retaining wall design. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Sea-Port Dozing and Development, Inc. E-1 1126 April 15, 2004 Page 9 To reduce the potential for hydrostatic pressures to build up behind the walls, retaining walls should be backfilled with a free-draining material extending at least eighteen 118} inches behind the wall. The remainder of the backfill should consist of structural fill. The free draining backfill should consist of sand and gravel with a fines content of less than 5 percent, based on the minus 3/4-inch fraction. A rigid, schedule 40, perforated PVC or SDR 35 drain pipe should be placed at the base of the wall and should be surrounded by a minimum of one cubic foot per lineal foot with one inch drain rock. The pipe should be placed with the perforations in the down position. The remainder of the backfill should consist of structural fill. A typical retaining wall backfill detail is provided on Plate 3. Seismic Design Considerations The Puget Lowland is classified as a Seismic Zone 3 in the 1997 Uniform Building Code (UBC). Earthquakes occur in the Puget Lowland with regularity, however, the majority of these events are of such low magnitude they are not felt without instruments. Large earthquakes do occur, as indicated by the 1949, 7.2 magnitude earthquake in the Olympia area and the 1965, 6.5 magnitude earthquake in the Midway area and the 2001 , 6.8 magnitude Nisqually earthquake. There are three potential geologic hazards associated with a strong motion seismic event at this site: ground rupture, liquefaction, and ground motion response. Ground Rupture The strongest earthquakes in the Puget Lowland are widespread, subcrustal events, ranging in depth from thirty {30) to fifty-five (55) miles. Surface faulting from these deep events has not been documented to date. Therefore, it is our opinion, that the risk of ground rupture at this site during a strong motion seismic event is negligible. � Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Sea-Port Dozing and Development, Inc. E-1 1 126 April 15, 2004 Page 10 Liquefaction Liquefaction is a phenomenon in which soils lose all shear strength for short periods of time during an earthquake. Groundshaking of sufficient duration results in the loss of grain-to-grain contact and rapid increase in pore water pressure, causing the soil to behave as a fluid. To have a potential for liquefaction, a soil must be cohesionless with a grain size distribution of a specified range (generally sand and silt); it must be loose; it must be below the groundwater table; and it must be subject to sufficient magnitude and duration of groundshaking. The effects of liquefaction may be large total and/or differential settlement for structures founded in the liquefying soils. In our opinion, the potential for widespread liquefaction-induced settlement at this site is negligible. The absence of a shallow groundwater table and the generally medium dense to dense condition of the soils is the primary basis for this conclusion. Ground Motion Response The 1997 UBC Earthquake regulations contain a static force procedure and a dynamic force procedure for design-base shear calculations. Based on the encountered soil conditions, it is our opinion soil profile type Sc, Very Dense Sorl or Soft Rock as defined in Table 16-J should be used to characterize the site soils. Excavations and Slopes The following information is provided solely as a service to our client. Under no circumstances should this information be interpreted to mean that ECI is assuming responsibility for construction site safety or the contractor's activities; such responsibility is not being implied and should not be inferred. The inclination of temporary slopes is dependent on several variables, including the height of the cut, the soil type and density, the presence of groundwater seepage, construction timing, weather conditions, and surcharge loads from adjacent structures, roads, and equipment. Because of the many variables involved, the inclination of temporary excavation slopes should be further evaluated during construction, as the actual soil and groundwater conditions become more apparent. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Sea-Port Dozing and Development, Inc. E-1 1 126 April 15, 2004 Page 11 In no case should excavation slopes be greater than the limits specified in local, state {WISHA), and Federal (OSHA) safety regufations. Based on the information obtained from our subsurface exploration, the medium dense soils encountered in the upper two to four feet at our test pit locations would be classified as Type B by OSHA/WISHA. Temporary cuts greater than four feet in height in Type B soils should be sloped at an inclination of 1 H:1 V {Horizontal:Vertical). The underlying dense soils would be classified as Type A by OSHA/WISHA. Temporary cuts greater than four feet in height in Type A soils should be sloped at an inclination of 0.75H:1 V. If seepage is encountered in site excavations, the soil should be considered a Type C soil by OSHA/WISHA. Temporary cuts greater than four feet in height in Type C soils should be sloped at an inclination of 1 .5H:1 V. If slopes of this inclination, or flatter, cannot be constructed, temporary shoring may be necessary. ECI should observe temporary excavations during construction to verify the OSHA Soil Type. Shoring will help protect against slope or excavation collapse, and will provide protection for workers in the excavation. If temporary shoring is required, we will be available to provide shoring design criteria. Permanent cut and fill slopes should be inclined no steeper than 2H:1 V. Cut slopes should be observed by ECI during excavation to verify that conditions are as anticipated. Supplementary recommendations can then be developed, if needed, to improve stability, li . including flattening of slopes or installation of surface or subsurface drains. Permanently exposed slopes should be seeded with an appropriate species of vegetation to reduce erosion and improve stability of the surficial layer of soil. Site Drainage Moderate to heavy groundwater seepage was encountered at our test pit locations excavated as part of this study at depths ranging from one and one-half (1 .5) to ten and one-half (10.5) feet below existing grade. The observed seepage is likely indicative of seasonal perched groundwater collecting along the contact with the underlying dense soils encountered at our test pit locations. � i Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY � Sea-Port Dozing and Development, inc. E-1 1126 ! April 15, 2004 Page 12 ' Based on the conditions observed during our subsurface exploration, perched groundwater seepage will likely be encountered in excavations if the grading is conducted during the wet season. If grading is conducted during the dry season, the potential and magnitude of seepage should decrease. If seepage is encountered in foundation or utility excavations during construction, the bottom of the excavation should be sloped to one or more shallow sump pits. The collected water can then be pumped from these pits to a positive and permanent discharge, such as a nearby storm drain. Depending on the magnitude of such seepage, it may also be necessary to interconnect the sump pits by a , system of connector trenches. ' During construction, the site must be graded such that surface water is directed off the site. Water must not be allowed to stand in areas where buildings, slabs, or pavements are to be constructed. Loose surfaces should be sealed by compacting the surface to reduce the potential for moisture infiltration into the soils. Final site grades must allow for drainage away from the residence foundations. The ground should be sloped at a gradient of 3 percent for a distance of at least ten feet away from the building, except in paved areas, which can be sloped at a gradient of 2 percent. Footing drains should be installed around the residence perimeters, at or just below the invert of the footing, with a gradient sufficient to initiate flow. A typical detail is provided on Plate 4. Under no circumstances should roof downspout drain lines be connected to the footing drain system. Roof downspouts must be separately tightlined to an approved discharge. Cleanouts should be installed at strategic locations to allow for periodic maintenance of the footing drain and downspout tightline systems. Utility Support and Backfill Utility trench backfill is a key concern in reducing the potential for settlement along utility alignments, particularly in pavement areas. It is important that each section of utility line is adequately supported in the bedding material. The material should be hand tamped to provide support around the pipe haunches. Fill should be carefully placed and hand tamped to about 12 inches above the crown of the pipe before heavy compaction equipment is brought into use. The remainder of the trench backfill should be placed in lifts having a loose thickness of less than twelve (12) inches and compacted to the appropriate structural fill requirements. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Sea-Port Dozing and Development, Inc. E-1 1 126 April 15, 2004 Page 13 Pavement A�eas The adequacy of site pavements is related in part to the condition of the underlying subgrade. To provide a properly prepared subgrade for pavements, the subgrade should be treated and prepared as described in the Site Preparation and General Earthwork section of this report. This means at least the top twelve (12) inches of the subgrade should be compacted to 95 pe�cent of the maximum dry density (per ASTM D-1557-91 }. It is possible that some localized areas of soft, wet or unstable subgrade may still exist after this process. Therefore, a greater thickness of structural fill or crushed rock may be needed to stabilize these localized areas. The following pavement sections are applicable to parking and drive areas that will be subjected to primarily passenger vehicles and occasional truck traffic: � Two inches of asphalt concrete (AC) over four inches of crushed rock base (CRB) material, or • Two inches of AC over three inches of asphalt treated base (ATB) material. We can provide pavement recommendations for areas that will receive heavy t�affic, if needed. Pavement materials should conform to WSDOT specifications. The use of a Class B asphalt mix is suggested. LIMITATIONS Our recommendations and conclusions are based on the site materials observed, selective laboratory testing and engineering analyses, the design information provided us, and our experience and engineering judgment. The conclusions and recommendations are professional opinions derived in a manner consistent with that level of care and skill ordinarily exercised by other members of the profession currently practicing under similar conditions in this area. No warranty is expressed or implied. Earth Consultants. Inc. GEOTECHNICAL ENGINEERING STUDY Sea-Port Dozing and Development, Inc. E-1 1 126 April 15, 2004 Page 14 The recommendations submitted in this report are based upon the data obtained from the test pits, laboratory test data, and our visual observations. Soil and groundwater conditions between test pits may vary from those encountered. The nature and extent of variations between our exploratory locations may not become evident until construction. If variations do appear, ECI should be requested to re-evaluate the recommendations of this report and to modify or verify them in writing prior to proceeding with the construction. Additional Services As the geotechnical engineer of record, ECI should be retained to perform a general review of the final design and specifications to verify that the earthwork and foundation recommendations have been properly interpreted and implemented in the design and in the construction specifications. ECI should also be retained to provide geotechnical services during construction. This is to observe compliance with the design concepts, specifications or recommendations and to allow design changes in the event subsurface conditions differ from those anticipated prior to the start of construction. We do not accept responsibility for the performance of the foundation or earthwork unless we are retained to review the construction drawings and specifications, and to provide construction observation and testing services. 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'� . ._ y� i � ' ;� a.. � �a - ,.'- r # 'E. . -_-• ' '.� -_ .'�� ., ;� �a.� �#� � ` _ : . ,:� ,t:,r, .._ , �,�., - . . re���n z� _ -� � , v� . . . . � t�;R . i ' ��� . ��4R r Y:,r . , • �.�y . * _ � . . � . �o .. � -, . =y� �. �4�����g�� ' . .. . i- h..i . . . . � :! .. . - � - `- . i . . -� • , ei •_ ' - , ..- � ��d �` �-4 Earth Consultants, tnc. • 'Geotechnical En�neering Geology.Environmerital Sciences Reference: �; `� Constnicnon Tesfmg&ICBO 1 WABO Inspection Se.rvices King Counly �"����;�.-�`� Map 656 � By Thomas Brothers Maps Vicinity Map � Dated 2004 Arnber Lane � Renton, Washington � NOTE:This plate may contain areas of color. � ECI cannot be responsible for any subsequent Drvvn. GLS Date April 2004 Proj. No. 11126 misinterpretation of the information resulfing ��ked STS Date 4/7/04 Plate 1 from black&white reproductions of this plate. N.E. 4th STREE7 - - - -- -- ► � I I I i j Existing � House i r---, j � � i �9 i i i , i i I --- � � i I � i � � a TP-4I - —■— I i I j ��-2 I �r -�- � TP�I = � �P-1 I —■— � �� .y�,, � ' � � = � y- � ., - l � . �`�� . . . I J1! �� � - l�.L1�C � ����i TP-1—f—Approximate Location of �� ECI Test Pit, Proj. No. v E-11126, Apri12004 Not - To - Scale Subject Site �`'��°�., E � Earth Consultants, Inc. �, ceole�vrical Engneer�ng,ceaogy.E„vtronrr�en,al s�i�es �--, � Wetland Area � r= �o���on�5�,g���Bo�W�o����„�n���5 ��= � (Delineated By Others) �' � Test Pit Location Plan ; Lot Number Amber Lane Renton, Washington ' NOTE:This plate may contain areas of cobr. ECt cannot be responsible for any subsequerrt ��• GLS Date April 2004 Rrot. No. 11 i 26 misinterpretation of the information resulting I from bladc&white reproductions of this plate. Checked STS Date 4R/04 Plate 2 -- -- - - ----- l i - ---- --- i I � ' i ' � Free Draini i � 18 inches min. i 1 - Backfi ll I ' �u° 111=111=111= i l Min 2"Dia. o0 0� o� 12 inches M - -'�'::: ;=`�;=: -=�"'' . II IIII II I ; , �....:: '_;::•: :,., � Weep Hole o oe°� '•::ci ��=::�:��::��:: -�:' :�::'� � o� �" ��' u- • :,,.o. : 0 0 0 � �•opv o0 ooa o _ •:t�•M i � o o p Q- � p po00 o p oo p �Q� . a o o a a '�' . ''O I i o0 o C 0�0� � O a��o�o0 •���::-�w� � �D t ro� flo o��oo�do �p� •D ' I I Min. 6� ao 0 0. �`Drain ° ��o � �00 � :� .•ti: I ' o opo 000 , o oboo o��'.�o ; illllllll ao 0o a� Rock o0 0�0 0 °o�a a�o ..,:a..;:'� �.—Excavated Sbpe J ac �o o ' 9 0 0 o p o0 0 ��� •p•: � o o •: : I �o�fl�O a o QO o I �o �a� � ���o��o � O�.♦ i O O° D � 0�0o OO O.•o.•�.c ; WEEP HOLE DETAIL �°o0 0 0 °oo° °� :'o' OOa aO o4Do0 0 0 0°0 0 °°o�o 0 0 '. Perforated Pipe 111=111=111 0� °o 0 0 0 o fl� o .°: : Wrapped with � lfoot min. °°"��'� '� � � Ftter Fabric a � _ I 1 foat min.Compacted Subgrade � � ii STANDARD NOTES 1 FTFNQ ` i 1) Free Draining bacldiH should consist of =: Surface Seal; Native Soil or other Low granular soil having no more than 5 �:� permeability Material percent passing the#200 sieve and i no particles greater than 4 irx;hes in o°o°° Free Draining Backfill � diameter. The percentage of particles o 0 0 passing the#4 sieve should be between 25 and 75 percent :, :�'� I `='= ' Structural Fill com cted to 90 ercerrt ro--!'o:o. Pa P ' relative compaction j 2) Structural backfill should be free of ao�aa� � organics, clayey soils,debris and other °o;o o�o 0 1 inch Drain Rodc � deleterious materials. It should be a ° °� a i placed at or near the optimum moisture � conterrt. � SCHEMATIC ONLY- NOT TO SCALE 3j Where weep holes are utilized, surround NOT A CONSTRUCTiON DRAWING each weep hole with 3 cubic feet of 1 inch ; drain rock.Maximum horizontal spacing �. � � of weep holes should be 6 feet. �� `� ; � �Earth Consultants, Inc. � ��'�C'�eotechnical Engvieers,Geobgists 5 Environmerstal Scieniists ! 4) Drain pipe;perforated or slotted rigid . � consrcuction�'esfing��CBO/wpBo trLspection Services i PVC pipe laid with perforations or slots "`'�� ! facing down;tight jointed; with a positive RETAINING WALL DRAINAGE AND BACKFILL � grad"ient. Do not use fle�dble com�gated � Amber Lane iplastic pipe. Drain Gne should be bedded Renton, Washington i on and surround with free draining 1 inch + drain rock.The drain rodc may be � � encapsulated with a geotechnical drainage Drwn. GLS Date April 2004 Proj. No. 11126 � fabric at the engineers discrefion. � Cfiecked STS Da#e 4/g/p4 Platg 3 � � � — -- --- I i � i � � i � I I I ' , ' - I � , -- � __ Slope To Drain _ � � ; ��— .S t. I :'�' '.ti'•''��.�!� j , _ - •.1�`�� •`�'��� �l•�l� � �f�• •t~` i 6 inch min. �:;;f. ':�:; :::: ;:::: .:f;;:: :'t= � � �i���� � ••••1�:•.•�� •�i•�•. .�:��ti:.•-�:..!;�..~�N:� ::.�1 � . . � . •j.�t:': ��. . I I — ''o.a-o"�'�o o'o'v'a�o o'�%�o;,00i5" o�o'o aoo�o I � � o o p oo�O �� �� �� °o�O �� a �a °o o°b° o 0 0 0 �0 O o9�° o 0 0 0 o O�ocb� o o a Q �$IflCfl �oo�o°�o�� Doo�oo�o�a aoo�oa rl'IIR. ap °aD a� O �po�p �oD o� D �po�p o��a�p o e�poda00� fl 0 a�0a�o00° �� e—poa� I I oa o � a oe e 0 � eo o p � p o o �D � � p o o �O � � p o 0 o°� o°bo 00°p o 000 0°00 00�o a o00 00 4inchmin. 000app o OQ OOQ000O p� �� �Opaa O ° o O Op�O � 0�� O Dp�O � � ° a I Diameter o°a°o 00 0�,�°°o °°o o ° ° � Perforated Pipe oo�o o o o a o000�a o o � Wrapped in Drainage �' ° °aoO o °°� �° ° °� ( a �0° O p a0�a ppp°0� O FabriC � o o � ' � �O oQ oo �oo , O o �O O a a o �r � _ � � � ! 2 inch min./4 inch max. 2 inch min. � � 12 inch ' j rrun. I I i i t � FrFNn i � :...:•� Surface seal;native soil or other SCHEMATIC ONLY- NOT TO SCALE i . --•::•:: � � :: bw permeability material. NOT A CONSTRUCTION DRAWING I � � O ° o { i °° °�° 1"Drain Rock i °O�o i I Drain pipe; perforated or slotted rigid �"``� '; O PVC pipe laid with perforations or ; ��� Earth Consultants, Ir1C. '! slots facing down;tight jointed��h a �F � �«echNcal EngineerS Geobgists 6 Environmental Scientists II `_ � �. j Construciion Testing�ICBO/WABO InspeQion Sen�ices i� positive gradient. Do not use flexible •�;,,�;,_ oorrugated plastic pipe. Do not tie building downspout drains inm footing �P�CAL FOOTING SUBDRAIN DETAIL I I lines. Wrap with Mirafi 140 Filter Fabric Amber Lane � or equivalent Renton, Washington � Drwn. GLS Date April 2004 Proj. No. 11126 � I Chedced STS Date 4/8/04 Plate 4 � I i APPENDIX A FIELD EXPLORATION E-11126 ' Our subsurface exploration was performed on April 6, 2004. The subsurface conditions at the site were explored by excavating four test pits to a maximum depth of eleven and one-half (11 .5) feet below existing grade. Test pits were excavated with a John Deere 310 SE rubber-tired backhoe, provided by the client. Approximate test pit locations and elevations were estimated based on pacing from existing features depicted on a preliminary site plan provided by Core Design, Inc. The locations and elevations of the test pits should be considered accurate only to the degree implied by the method used. These approximate locations are shown on the Test Pit Location Plan, Plate 2. ' The field exploration was continuously monitored by a geologist from our firm who classified the soils encountered, maintained a log of each test pit, obtained , representative samples, measured groundwater levels, and observed pertinent site I features. The samples were visually classified in accordance with the Unified Soil � Classification System (USCS1, which is presented on Plate A1 , Legend. Representative soil samples were collected and returned to our laboratory for further examination and testing. Logs of the test pits are presented on Plates A2 through A5. The final logs represent our interpretatians of the field logs and the results of our laboratory examination and testing. The stratification lines on the logs represent the approximate boundaries between soil types. In actuality, the transitions may be more gradual. Earth Consultants, Inc. MAJOR DIVISIONS GRAPH LETTER TYPICAL DESCRIPTION SYMBOL SYMBOL G�/ Well-Graded Gravels, Gravel-Sand Andvel Clean Gravels Q �a �a � gW Mixtures, Little Or No Fines Gravelly (little or no tines 1 ` � Coa�se Soils . , , GP � Poorry-Graded Gravels,Gravel- Grained � � � gp Sand Mixtures,Little Or No Rnes Soils More Than GM Sitty Gravels,Gravel-Sand- �03o Coarse Gra�els With gm Silt Mixtures raction Fines(appreciable Retained On amount of fines) (aC Clayey Gravels,Gravel-Sand- No. 4 Sieve (�C Clay Mixtures Sand � �o 000 'o S�/ Well-Graded Sands. Gravelly And Clean Sand o 0 o p o SW Sands. Little Or No Fines Sandy (�ittle or no fines! ::_*: ;.:, ;;�,.:: hlore Than Soils G. '!::� ` sP Poorly-Graded Sands, Gravelly ;�.<z:a:'�:�>�?fz S Sands, Little Or No Fines 50'�= Material p Larger Than More Than No.200 Sieve gp� Coarse SM Silty Sands, Sand- Silt Mixtures Size Fraclion Sands With Sfll Fines(appreciablF� Passing No.4 amount of fines j :' SC Sieve / / SC Clayey Sands, Sand-Clay Mixtures I I I i ' i�; ML Inorganic Silts 8 Very Fine Sands,Rock Flo�r,Silty- I � m� Clayey Fine Sands;Ctayey Silts w/ Slight Plasticity ;I Fine Silts Liquid Limit ! CL �norganic Clays Of Low To Medium Plastic:ty, Grained �d Less Than 50 � C� Gravelly Clays. Sandy Clays, Silty Clays, Lean Soils Clays I I 1 QL Organic Silts And Organic I � I � I � OI S�iry ciays or �ow Plasticity MH Inorgar�ic Silts, Micaceous Or Diatomaceous FirE More Than ITlfl Sand Or Silty Soils 50"� Mater�al Silts Liquid Limit Smaller Than qnd CH Inorganic Clays Of High No 200 Sieve Ctays Greater Than 50 C�l PlasticiJy, Fat Clays. Size /// // /�/�� OH Organic Clays Of Medium To High Ofl Plasticity, Organic Sitts `L�, `��, ,", pT Peat, Humus, Swamp Soils Highly Organic Soils �, ��i, ��i, ��i pt With Hiah Organic ConteRts Topsoil 'y y'y`�"� Humus And Duff Layer Fill Hiyhly Variable Constituents The discussion in the text of this report is necessary for a proper understanding of the nature ot the material presented in the attached logs. DUAL SYMBOLS ere used to lndicate borderline soil dassification. C TORVANE READING,tsf I 2"O.D. SPLIT SPOON SAMPLER qu PENETROMETER READING,tsf W MOISTURE, %dry welght � 24"I.D. RING OR SHELBY TUBE SAMPLER P SAMPLER PUSHED * SAMPLE NOT RECOVERED i WATER OBSERVATION WELL pci DRY DENSITY, Ibs. pe�cubic ft. LL LIQUID LIMIT, % Q DEPTH OF ENCOUNTERED GROUNDWATER PI PLASTIC INDEX DURING IXCAVATION i $UBSEQUENT GROUNDWATER LEVEL W/DATE � Farth Consultants �nc. LEGEND Gizmx I:nicJ l��gii iccrs,(:�x�lugists&l�nviruniucr�l,d Siri;nlists Proj. No. iii26 Date nPr�i zoo:� Plate Al Test Pit Log Projec�Name: Shcet d Amber Lane 1 1 Job No. Logged by: Date: Test Pit No.: � 11126 STS 4/6/04 TP-1 Ezcavation Contackor. Ground Surface Elevation: Client Provided 435' Notes: ��� w L $ L Q � $ surface c«xiaions: Depth of Topsoil &Sod 6": short grass Notes ("/,) 1O � o " � � �. c9 cn �n cn SM Brown silty SAND, medium dense, moist � -trace gravel and charcoal fragments 2 SM Light brovm silty SAND with gravel,dense, moist 3 -iron obde staining �o.� 4 -18.6%fines 5 -trace cobbles s � 8 -increase in moisture content 13.3 9 �� Test pit terminated at 10.0 feet below ebsting grade. Groundwater OTESe encountered at 8.5 feet during e�acavation. Test pits w�ere ezcavated using a John Deere 310 SE rubber tired backhoe provided by the client. Test�it elevations estimated based on topographic data shovm on the Site Plan provided by the Client. e 5 0 � U w � a � Test Pit Log Earth Consultants Inc. Amber�ane �j rx-�rclmkalFi�gtnr<c�s.Grok��x,Fnv�mnmenra:5ck�nttx� Renton, Washington � a � W Proj.No. 11126 Dwn. GLS Date April 2004 Chedced STS Date 4R/04 Plate A2 Subsurface conditions depic.ied represent our observations at the time and location of this e�lorffiory hole,modified by engineering tests,anafysis and judgment. They are not necessarily representative of other times and locations.We cannot acoept responsibility for the use or interpretation by others of �..s.,.,,,��...,.��o.,«�.,.,�ti��i,,., Test Pit Log �r�: sneet or Amber Lane 1 1 Job No. Loc�ged by: Date: Test P"it No.: 11126 STS 4/6/04 TP-2 � F�acava�ion Contador: Ground Surfaoe Elevation: Client Provided 436' Mates: G�e1,n,�era� W `-' $ � � u� � Surfaoe Conditions: Depth of Topsoil 8�Sod 6": short grass IR/le$ ���� � T 0 LL i0 � T (� Cn f/� Ul SM Brown silty SAND, medium dense, moist to w�et � -contains gravel 2 3 SM Light brovm silty SAND with grav�el,dense, moist 4 -iron o�de staining �o.� 5 -contains cobbles s � -moderate caving of test pit walls due to seepage 8 -increase in moisture s ��.� �o �1 Test pit terminated at 11.0 feet below e�as6ng grade. Groundwater seepage encountered at 2.5,4.0 and 7.0 feet during ezcavation. 0 � < 0 � U W � a � Test Pit Log �arth Consultants Inc. Amber�ane o �`�`y��,��F"�`�.�`w`��,R�,�n",�„����"tt� Renton, Washington � a � w Proj.No. 11126 �wn. GLS Date April 2004 Chedced STS Date 4/7/04 Plate A3 Subsurface cond'itions depided repre5ent our observations ffi the time and location aF this e�loratory hole,modified by engineering tests,analysis and judgrnent. They are not necessarily representative of other times and Iocations.We cannot accept responsibility for the use or interpretation by others of �.,�.,...,��..,..ve�o..+�,..,�tic�i.,.. Test Pit Log Ptoject Narne: Sheel of Amber Lane 1 1 Job No. La,�ed by: Dmte: Test Pit No.: 11126 STS 4/6/04 TP-3 6acavation CoMactor: Ground Surface Elevation: Client Provided 434' Naes: � o L m N o su�ace c«,daions: Depth of Topsoil 8 Sod 3": short grass Generdl W Q� Q . a � a Notes (u/o) `° �. p "' W � E. c9 � �n cn SM Brown silty SAND with grav�el, medium dense, moist 1 -contains grav+el and organics I �8 2 -increase in moisture, 28.6%fines 3 -moderate caving of test pit walls due to seepage 4 -becomes light brown, iron obde staining 5 -becomes dense s � Test pit terminated at 7.0 feet below ebsting grade. Groundwater seepage encountered at 2.5 feet during e�acava6on. I I � � I o I � I o O i W � a c� � Test Pit Log � Farth Consultants inc. Amber�ane � O Gcxltecimi�-alFY�g7necas,Gr.c�ts't�&F]rvlrmn�erualtic:ksilL� Renton,Washington H a � W Proj.No. 11126 Dwn. GLS Date April 2004 Checaced STS Date 4/7/04 Plate A4 Subsurface conditions depicted represent our observations at the time and location of this e�loratory hole,modified by engineering tests,analysis and judgment. They are nvt neoessarily representativE of other times and locations.We cannot accept responsibility for the use or i�terpretation by others of .,�.Y..,�r,,,,.,.r�o.,�o.+.,,,rhk i,,.. Test Pit Log Project Name: Sheet aF Amber Lane 1 1 Job No. Logc�ed by: Date: Test Pit No.: 11126 STS 4/6/04 TP-4 E�avation Contador: Ground Surface Elevation: Client Provided 434' Naes: � — „ surraoe condaions: Depth of Topsoil &Sod 18": short grass General W a g o. _: a c`ni � Notes (% `° �, m LL' � u� T � c7 �n � �n � � y TPSL TOPSOiL and organics y � � 2 SM Brown silty SAND with gravel, medium dense, moist to wet 3 -becomes light brown and dense 4 -contains cobbles, iron obde staining 5 s -increase in moisture, becomes medium dense 11.3 7 -moderate to heavy caving of test pit walls due to seepage , 8 -increase in sand content, decrease in gravel content � �! s �I -33.4%fines 17.5 I 10 �� SP-SM Brown poorly graded SAND with silt, medium dense, wet, heavy o ' seepage at 10.5 Test pit terminated at 11.5 feet below ebsting grade. Groundwater seepage encountered at 1.5 and 10.5 feet dunng excavation. e a 0 c� U w � a � Test Pit Log � �arth Consulranrs Inc. Amber�ane o `.`."'�,,,,�'F"�"�'"�`�,�.F.��""'°'P"`�'s"""�' Renton,Washington � a � W Proj.No. 11126 own. GLS Date April 2004 Chedced STS Date 4/7104 Plate A5 Subsurface conditions depicted represent our observations at the time and location of this e�loratory hole,modified by engineering tests,analysis and judgment. They are not necessarily representative of other times and locations.We cannof accept responsibility for the use or interpretation by others of �.,�„r.,,�«�.,.,.,��a.,��,,.,,ti��i,,,. APPENDIX B LABORATORY TEST RESULTS , E-11126 I Earth Consultants, Inc. Particle Size Distribution Report c � p Y r p(yp♦ T � 0 A N ' � F � e3 �[ R R � R � i ! �� I , I � ' i , I I ij I i � I 90 ' i I I I ' i i i I I 80 ' �� � ' � I --- 7� � '� i i i � �' �'� ' � ' �� � � � ;i �� i;� i I � � � i Z � - ' � �; ' W � I ' j � � I �! ' � � � , w � � � � a ; ' i i ' i I 30 ;� 20 � ;� ; � I I , I; � i i I 10 � I, � � 0 i ' 200 100 10 1 ; � 0.1 0.01 I 0.001 GRAIN SIZE- mm 96 COBBLES %GRAVEL %SAND %SILT 96 CLAY USCS AASHTO PL LL � 26.3 55.1 18.6 SM � I 9.1 52.3 28.6 SM 0 3.8 62.8 33.4 SM SIEVE PERCENT FINER SIEVE PERCENT FINER SOIL DESCRIPTION inches J � ,� number ,� ` � G TP-1:4'-SM size �e ^ Light brow�n silty Sand with gravel, ]0.19% 1.5 100.0 100.0 100.0 #4 73.7 80.9 96.2 moisture 3/4 100.0 100.0 100.0 #8 67.7 72.1 90.1 ❑TP•3:2'-SM 318 82.8 89.2 99.7 #16 62.7 66.1 85.1 #30 52.2 61.0 78.1 �OK7 silty Sand wiin gravel(contains #50 4l.7 51.5 62.9 organics),26.8%moisture #100 28.4 38.5 43.4 �Tp-�� lo'-SM #200 18.6 28.6 33.4 Light brown silry Sand, 17.5°%moisture GRAIN SIZE REMARKS: �gp 0.966 0.545 0.271 c STS �30 0.164 0.0836 p�p ❑STS COEFFICIENTS C� � STS Gu o Source: Sample No.:TP-1 Elev./Depth:4' ❑Source: Sample No.:TP-3 Elev./Depth:2' .� Source: Sample No.:TP-4 Elev./Depth: 10' EARTH Client: Project: Amber Lane,Renton CONSULTANTS, INC. pro'ectNo.: E-11126 Plate B1 DISTRIBUTION E-11126 4 Copies Sea-Port Dozing and Development, Inc. P.O. Box 3015 Renton, Washington 98056 Attention: Mr. Robin Bales � � Earth Consultants, Inc. � N .. �. � � C� � W x � 0 � � � VIII. ESC ANALYSIS AND DESIGN The erosion control design complies with the City of Renton standard, which is based upon the 1998 King County Surface Water Design manual. This standard requires a site that is less then 3 acres in size to utilize a sedimentation trap (instead of a sedimentation pond). The sizing for the trap is based upon the 2-year event, which is referred to as the water quality storm event, and the volume required to settle out silt. Sedimentation Trap Surface area: SA=Fs(Q�IVs) QZ = 0.18 CFS (see drainage calcs, developed timeseries, dev.ts fl Vs =0.00096 (given KCSWDM) Fs=2 (Factor of safety, KCSWDM) SA= 2*(0.18 / 0.00096) SA= 354 SF—required SA=450 SF—provided (30 x 15) i�:�_� i� ��i i� IX. OPERATIONS AND NIAINTENANCE MANUAL �,. ; A. King County Complaint Overview � i page� B. KCRTS Output Listing (8 pages) C. Figure 2 - Site Plan �i page> D. Figure 3 - Site Cover � i page> E. Figure 4 - Existing Site Hydrology � i Page� F. Figure 4 - Developed Site Hydrology � i page� ,� , , i . Map Output Page 1 of 1 � King County ��'� • - � iMAP - Stormwater u. npt`i S+!!� �'�'- �1:N; 74.�� Lit�t! 't,t �` y!�v,� 1t16Ci u�ij: . . ..., . f:? . u,L�r u er� u �� . . �`!'i=� Jiy`� .. � u��,�i S.:J � � � " _. .. : . 97•f!� . _.. .�,�,j.li,�.Js;+ i a� �. ' Fl� ; • ' 'il�:! W 4•'J' � � 4f�SI u.!� - T � _! Q[135t c�0t110���1i�,_��£J4U'd�. u r�, u iu£ � .yr'e'�d5 } 9U3< _�;i+.� ;i�r:i Z �Z , !YJ31 uJt? w4L�T7 �t�f8 4�z � 9Lr.9 urf�+ ��� . ,.,. � :�71R ' � �� _ 1_ .. _���.p J_�!1�Fi ; E--- '45 . yr�i�i ,_, t �I fl 9!(� gfri� u!�S � (K�i:' y?y_� 1. 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' -� ,F, ��r �� � _ c 4`J15 ���� �� �.;[�.;� j i FJ'US t..i �.��,:, n��y _t_ib� 7���< :7 a �:�s�1 a3�_� W���.. � { i:� �'� v�ou > � w '�',� �33 r-~- Q ',�ritt6 >:_+' J 5,' ���� � � n�a�l��p;�f OiUT = CkJ66_��0��74 _�'Jt1 Q 2 �<� �1U?A u}rK ��ty n &'_� ' 0�2!J G�7� �' �i3 J�r'! � :XJfl4 � + ��1,,� i�:1h' 97'_�S 4J15 ��,n `260� � � iW t � .- =r _� t�iNST! _v_�.E: '.kJtS 9� !kl£f! y :.4. �, H� `� �� w'� 4JJ5 J�4tJ � GitS a� �,.� :�1��t r���f t.:�i'-.� � y(��; � ��TSUAi r1{rrt � �: . ,. ��4�:� i i u�„�-t � }'^�,� �j C�'t�`�''� 13 :1�;. �, i �i wr� �i �. `�t3�i- 'i1}i o'i� J5!!! tXJ4L� _���_i _ � C��� C�Syt� ' p��_i �'t� �:17. , SE ZNC? i tE rl . .i�ri�i - ��. Q6�J ', C��(: � . `;f_ t!ti k , �•<� - - 4��t tiE. 1�01+•1 5; o°,I� I `i�� � x_�70�Uf 1!J '_�1�� p�t;r� �. '�- ` L�3� €. �Dit4546 �7 i5 , -.- _ �qr s.�, - n{i:� '� "a" � � v olG; t . vZ ' `°•!9�10 � ; u+�g � ,�F:;`? Cw�fO �}` ( d 41�1 � , � I i ; � ��c rwl=� �T ',ti � � � Z 4[)ti� �LK9r•,� u,�. ��15� 9065 �; _i�.lQ �� C +- �rt?ij'� a �� "' . b9i: -. ' �. �� ^ �;��E�. _ u•'„' y1.i'.� �C)Z047KinyG�un4y '/y3U �� y.'sts u;i}� ;�!b� un��y 0 0.2m1 Legend � lr»r�;d�Brcafti�rr�R'k��Paye 5treet� � 5irV5 Dra+aiage 51ud�es ��v,,,,. � 5VY5 Nie�yhborhood Dra�na�e n� , P+v}aLis I �.R l � 5VY5 Reg�na(5lorttmaler Par;.�� Fa�'�'B� Contours-2D tt. ` 54V5 RssrJenl�a�5tomnrater L� Lakes aaid Ly��e Fi,VZK Fa�lie5 r, 5treat7� � 5W5,.oernr�sc+al5tmm��eiet Vb'LRD Dras�ay« �o•?��'-�n�= Faciti[i�s I'/'vJ+DQT2lB�.H�'e�h • � � � ����7iy B-�u•�:fa�Y he information included on this map has been compiled by King County staff from a variety of sources and is subject to change without notice. ing County makes no representations or warranties,express or implied,as to accuracy,completeness,timeliness,or rights to the use of such nformation.King County shall not be liable for any general,special,indirect,incidental,or consequential damages including,but not limited to, ost revenues or lost profits resulting from the use or misuse of the information contained on this map.Any sale of this map or information on his ma is rohibited exce t b written rmission of Kin Coun . King Couniy�G15 Center�News�Services�Comments�Search By visiting this and other King County web pages,you expressly agree to be bound by tertns and conditions of the site.The detaiis http://www5.metrokc.gov/servledcom.esri.esrimap.Esrimap?ServiceName=overview&Cl... 12/21/2004 Retention/Detention Facility Type of Facility: Detention Vault Facility Length: 50 .00 ft Facility Width: 62 .00 ft Facility Area: 3100 . sq. ft Effective Storage Depth: 4 .00 ft Stage 0 Elevation: 430.00 ft Storage Volume: 12400. cu. ft Riser Head: 4.00 ft Riser Diameter: 12.00 inches Number of orifices: 2 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 0.56 0. 017 2 2.30 1.06 0. 040 4.0 Top Notch Weir: None Outflow Rating Curve: None Stage Elevation Storage Discharge Percolation (ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs) 0 .00 430 .00 0 . 0 .000 0.000 0 . 00 0 .01 430 .01 31. 0. 001 0.001 0.00 0 . 02 430 .02 62 . 0 . 001 0.001 0 . 00 0 . 03 430 .03 93 . 0.002 0.001 0 .00 0. 04 430 .04 124 . 0. 003 0.002 0 .00 0. 05 430.05 155. 0.004 0.002 0.00 0. 15 430.15 465. 0.011 0 .003 0.00 0.25 430.25 775. 0.018 0 .004 0.00 0 . 35 430.35 1085. 0.025 0 .005 0. 00 0 .45 430.45 1395. 0.032 0 .006 0 .00 0.55 430.55 1705. 0.039 0.006 0 . 00 0.65 430.65 2015. 0.046 0.007 0.00 0 .75 430.75 2325. 0.053 0.007 0.00 0. 85 430.85 2635. 0.060 0.008 0.00 0 .95 430.95 2945. 0.068 0.008 0.00 1.05 431.05 3255. 0.075 0. 009 0 .00 1.15 431.15 3565. 0.082 0. 009 0.00 1.25 431.25 3875 . 0.089 0. 010 0.00 1 .35 431.35 4185 . 0.096 0. 010 0.00 1 .45 431 .45 4495 . 0.103 0. 010 0.00 1 .55 431.55 4805 . 0_110 0 . 011 0.00 1 .65 431.65 5115 . 0.117 0.011 0 .00 1.75 431.75 5425 . 0.125 0.011 0 .00 1. 85 431.85 5735 . 0.132 0.012 0 .00 1. 95 431.95 6045. 0. 139 0 .012 0 .00 2 . 05 432 .05 6355. 0.146 0 .012 0.00 2 . 15 432 .15 6665. 0. 153 0 .013 0.00 2 .25 432 .25 6975. 0. 160 0 .013 0.00 2 .30 432 .30 7130. 0.164 0 .013 0 .00 2 . 31 432 .31 7161. 0.164 0 .013 0 . 00 2 .32 432 .32 7192 . 0.165 0.014 0. 00 I 2 . 33 432 .33 7223 . 0 .166 0 . 015 0. 00 2 .34 432 .34 7254 . 0. 167 0 .017 0.00 2 .36 432.36 7316. 0 . 168 0.019 0.00 2 .37 432 .37 7347. 0 .169 0.021 0.00 2 .38 432 .38 7376. 0.169 0.022 0.00 2 .39 432 .39 7409. 0.170 0.022 0.00 2 .40 432 .40 7440 . 0.171 0.023 0 .00 2 .50 432 .50 7750 . 0.178 0.027 0. 00 2 .60 432 .60 8060 . 0 .185 0.031 0.00 2 .70 432 .70 8370. 0.192 0.033 0.00 2 .80 432 . 80 8680. 0.199 0.036 0.00 2 .90 432 .90 8990. 0.206 0.038 0.00 3 .00 433 .00 9300 . 0.213 0.040 0.00 3 .10 433 .10 9610 . 0.221 0.042 0. 00 3 .20 433 .20 9920 . 0 .228 0.044 0. 00 3 .30 433 .30 10230. 0.235 0.046 0. 00 3.40 433 .40 10540. 0.242 0.048 0.00 3 .50 433.50 10850. 0.249 0.050 0.00 3 .60 433.60 11160. 0.256 0.051 0.00 3 .70 433 .70 11470. 0.263 0.053 0.00 3 .80 433.80 11780. 0.270 0.054 0.00 3 .90 433 .90 12090. 0.278 0.056 0.00 4 . 00 434 .00 12400. 0.285 0.057 0.00 4. 10 434.10 12710. 0 .292 0.366 0.00 4.20 434.20 13020. 0.299 0.931 0 .00 4.30 434.30 13330. 0.306 1.660 0 .00 4 .40 434.40 13640. 0.313 2.450 0 .00 4.50 434.50 13950. 0.320 2 .740 0.00 4.60 434.60 14260. 0.327 2 .990 0 .00 4.70 434.70 14570. 0.334 3 .230 0.00 4 .80 434 .80 14880. 0.342 3 .450 0.00 4 . 90 434.90 15190. 0.349 3 .660 0 .00 5.00 435.00 15500. 0.356 3 .850 0 .00 5. 10 435.10 15810. 0.363 4 .040 0 .00 5.20 435.20 16120. 0.370 4 .210 0 .00 5.30 435.30 16430. 0.377 4 .380 0.00 5 .40 435.40 16740. 0.384 4 .550 0.00 5.50 435.50 17050. 0.391 4 .710 0.00 5.60 435.60 17360. 0.399 4 .860 0.00 5.70 435.70 17670. 0.406 5.010 0.00 5. 80 435.80 17980. 0.413 5 .150 0.00 5. 90 435.90 18290. 0.420 5 .290 0 .00 6. 00 436.00 18600. 0.427 5 .430 0.00 H_,�d Inflow Outflow Peak Storage Target Calc Stage Elev (Cu-Ft) (Ac-Ft) 1 0.36 0.09 0 .11 4.02 434 . 02 12456. 0.286 � 0.18 ******* 0 .05 3 .66 433 .66 11342 . 0.260 � 0.18 0. 05 0.04 3 .23 433 .23 10016. 0.230 4 0.21 ******* 0.04 3 .16 433 .16 9791. 0.225 5 0.19 ******* 0 .03 2 .65 432 .65 8222 . 0.189 E 0.11 0. 03 0 .02 2 .34 432 .34 7255. 0.167 0.15 ******* 0 .01 2.12 432 .12 6586. 0. 151 � 0.16 ******* 0.01 1.49 431.49 4611. 0. 106 -- -------------------------------- Route Time Series thrcaah Facility �n=io;�r '�i..,,e ..�_-_�� Fil� :ce-�.`sf Outflow Time Series File:rdout Inflow/Outflow Analysis Peak Inflow Discharge: 0.358 CFS at 6 :00 on Jan 9 in Year 8 Peak Outflow Discharge: 0.113 CFS at 11 :00 on Jan 9 in Year 8 Peak Reservoir Stage: 4 .02 Ft Peak Reservoir Elev: 434.02 Ft Peak Reservoir Storage: 12456. Cu-Ft . 0.286 Ac-Ft Flow Frequency Analysis Time Series File:rdout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates-- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 0 .053 2 2/09/O1 20 :00 0.113 4.02 1 100.00 0.990 0 .013 7 1/07/02 4 :00 0.053 3 .74 2 25.00 0.960 0.043 4 3/06/03 22 :00 0.045 3 .23 3 10.00 0.900 0.010 8 8/26/04 7:00 0.043 3 .16 4 5.00 0.800 0.017 6 1/08/05 3 :00 0 .032 2 .66 5 3.00 0.667 0.032 5 1/19/06 0 :00 0 .017 2 .34 6 2.00 0.500 0.045 3 11/24/06 8:00 0 .013 2 .18 7 1.30 0.231 0.113 1 1/09/OS 11:00 0 .010 1.49 8 1.10 0.091 Computed Peaks 0 .093 4.01 50.00 0.980 Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS °s E % �I 0.001 28609 46.655 46.655 53 .345 0 .533E+00 0.002 7753 12 .644 59.299 40.701 0 .407E+00 0.004 6808 11.102 70.401 29.599 0 .296E+00 0.005 4257 6. 942 77.343 22 .657 0 .227E+00 0.007 4682 7.635 84. 979 15.021 0.150E+00 0 .008 4107 6.698 91. 676 8.324 0.832E-01 0.010 1304 2.127 93 .803 6.197 0.620E-01 0.011 2046 3.337 97.140 2 .860 0.286E-01 0.013 969 1.580 98.720 1.280 0.128E-01 0.014 435 0.709 99.429 0 .571 0.571E-02 0.016 17 0. 028 99.457 0.543 0.543E-02 0 .017 12 0.020 99.477 0 .523 0.523E-02 0.019 15 0. 024 99.501 0 .499 0.499E-02 0 .020 11 0.018 99.519 0 .481 0.481E-02 0.021 12 0. 020 99.538 0 .462 0.462E-02 0.023 22 0. 036 99.574 0 .426 0.426E-02 0.024 27 0. 044 99 .618 0 .382 0.382E-02 0.026 22 0.036 99 .654 0 .346 0.346E-02 0.027 26 0.042 99.697 0 .303 0.303E-02 0 .029 13 0.021 99.718 0 .282 C.282E-02 0 .030 13 0.021 99.739 0 .261 C .261E-02 0. 032 24 0. 039 99.778 0 .222 0.222E-02 0. 033 2� 0.041 99.819 0.181 0. 181E-02 0 .035 7 0.011 99.830 0.170 0. 170E-02 0.036 9 0.015 99.845 0.155 0. 155E-02 0 . 038 12 0. 020 99. 865 0 .135 0 . 135E-02 0 . ��3� -- 0 . .,�0 99 . ?� _ ., . 1_6 ., . 116�-0�. 0.041 10 0.016 99.901 0.099 0 .995E-03 � 0.042 9 0.015 99.915 0.085 0 .848E-03 ! 0.044 13 0.021 99.936 0.064 0 .636E-03 ' 0 .045 12 0.020 99.956 0 .044 0 .440E-03 0.046 8 0.013 99.969 0 .031 0 .310E-03 I 0.048 2 0.003 99.972 0.028 0 .277E-03 0.049 3 0.005 99.977 0.023 0 .228E-03 0.051 5 0.008 99.985 0.015 0 .147E-03 0.052 4 0.007 99.992 0.008 0 .815E-04 Hyd Inflow Outflow Peak Storage Target Calc Stage Elev (Cu-Ft) (Ac-Ft) 1 0.36 0.09 0 .11 4.02 434 .02 12456. 0.286 2 0.18 ******* 0.05 3 .66 433 .66 11342 . 0.260 3 0. 18 0. 05 0.04 3.23 433 .23 10016. 0.230 4 0.21 ******* 0.04 3 .16 433 .16 9791. 0.225 5 0. 19 ******* 0.03 2 .65 432 .65 8222. 0. 189 6 0. 11 0. 03 0.02 2 .34 432 .34 7255_ 0. 167 7 0. 15 ******* 0.01 2 .12 432 .12 6586. 0. 151 S 0. 16 ******* 0.01 1.49 431.49 4611. 0. 106 -; i � ! , Dsration Comparison Anaylsis I� Base File: predev.tsf New File: site.tsf Cutoff Units: Discharge in CFS -----Fraction of Time----- ---------Check of Tolerance------- Cutoff Base New �Change Probability Base New �Change 0.031 I 0.29E-02 0.31E-02 4.4 � 0.29E-02 0.031 0.032 3 .3 0 .034 I 0.25E-02 0.27E-02 9.9 I 0.25E-02 0.034 0.035 3 .9 0.037 � 0.20E-02 0.22E-02 8.2 I 0.20E-02 0.037 0. 038 2 .5 0.040 � 0. 15E-02 0.17E-02 15.7 I 0.15E-02 0.040 0. 042 4 .8 0.043 I 0. 11E-02 0.14E-02 21.7 � 0.11E-02 0.043 0. 045 6.6 0.046 � 0. 82E-03 0.11E-02 36.0 I 0.82E-03 0.046 0.049 8.0 0.049 � 0.54E-03 0.91E-03 69.7 I 0.54E-03 0.049 0.051 4 .3 0.051 � 0.36E-03 0.44E-03 22.7 � 0.36E-03 0.051 0.053 2 .0 0.054 I 0.26E-03 0.28E-03 6.3 � 0.26E-03 0.054 0.056 2 .2 0.057 I 0.18E-03 0.21E-03 18.2 � 0.18E-03 0.057 0.059 2 .6 0.060 I 0.15E-03 0.82E-04 -44.4 � 0.15E-03 0.060 0.059 -2 .3 0.063 I 0.13E-03 O.00E+00 -100.0 � 0.13E-03 0.063 0.059 -6.0 0.066 � 0 .33E-04 O.00E+00 -100.0 � 0.33E-04 0.066 0.061 -7.1 Maximum positive excursion = 0.004 cfs ( 10.0�) occuring at 0.044 cfs on the Base Data:predev.tsf and at 0 .049 cfs on the New Data:site.tsf Maximum negative excursion = 0.006 cfs ( -8.5g) occuring at 0.067 cfs on the Base Data:predev.tsf and at 0 .061 cfs on the New Data:site.tsf SITE. PKS Flow Frequency Analysis Time Series File:site.tsf Project Location:5ea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.062 2 2/09/Ol 19:00 0.122 1 100.00 0.990 0.017 7 1/05/02 16:00 0.062 2 25.00 0.960 0.051 4 3/06/03 22:00 0.052 3 10.00 0.900 0.012 8 8/26/04 2:00 0.051 4 5.00 0.800 0.019 6 1/08/05 3:00 0.040 5 3.00 0.667 0.040 5 1/18/06 23:00 0.019 6 2.00 0. 500 0.053 3 11/24/06 8:00 0.017 7 1.30 0.231 0.122 1 1/09/08 11:00 0.012 8 1.10 0.091 Computed Peaks 0.102 50.00 0.980 Page 1 DEV.PKS Flow Frequency Analysis Time Series File:dev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.178 6 2/09/O1 2:00 0. 358 1 100.00 0.990 0.146 8 1/05/02 16:00 0.230 2 25.00 0.960 0.213 3 2/27/03 7:00 0.213 3 10.00 0.900 0.158 7 8/26/04 2:00 0.190 4 5.00 0.800 0.190 4 10/28/04 16:00 0.188 5 3.00 0.667 0.188 5 1/18/06 16:00 0.178 6 2.00 0. 500 0.230 2 10/26/06 0:00 0.158 7 1.30 0.231 0.358 1 1/09/08 6:00 0.146 8 1.10 0.091 Computed Peaks 0.315 50.00 0.980 Paye 1 i � PREDEV.PKS Flow Frequency Analysis Time series File:predev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.068 2 2/09/Ol 18:00 0.087 1 100.00 0.990 0.019 7 1/06/02 4:00 0.068 2 25.00 0.960 0.051 4 2/28/03 3:00 0.052 3 10.00 0.900 0.002 8 3/24/04 21:00 0.051 4 5.00 0.800 0.030 6 1/05/05 8:00 0.044 5 3.00 0.667 0.052 3 1/18/06 21:00 0.030 6 2.00 0. 500 0.044 5 11/24/06 4:00 0.019 7 1.30 0.231 0.087 1 1/09/08 9:00 0.002 8 1.10 0.091 Computed Peaks 0.081 50.00 0.980 Page 1 SEC. 29, TWP. 23N, RGE SE., W.M. l � � � EXISTING z 3 � 36-INCH ' O N STORM �� I PI PE � 0 + 1 ` � 1 ` Z ` ` DETENTION �� ��' �r s �• D 20 �� BO & warER �� Qva�irY , , , VAULT PROPOSED � ,, ,, ; ,, , , , , ; WATER MAIN ,�I o FOOTING �� . 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