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HomeMy WebLinkAbout03703 - Technical Information Report - Drainage m N E 7t" ShOrt PIatS i � LUA13-000496; 13-000514; & 13-000867 � 3603 NE 7t" Street ' Renton, Washington 98056 � � N� L � v �d DRAINAGE REPORT 10 � �� (Comb�ne three short plats) July 29, 2013 Amended September 10, 2013 Prepared for: KRRV Development, LLC � CITY OF RENTON � Attn: Kyle Miller � RECEIVED � P.O. Box 908 SEP 2 4 2013 Ravensdate, Washington 98051 (425) 432-5932 office �VILDING D�vISION Prepared by: � �. , � . � Offe Engineers, PLLC �a WA� Darrell Offe, P.�E. ` . , �G, ` 13932 SE 159 Place � Renton, Washington 98058-7832 � w (425) 260-3412 office ��,q,� � (425) 227-9460 fax � � ��� darre6t.ofife@comcaston�t ��i'�1► `� _ � � � j � 37�� Table of Contents • Technicaf Information Worksheet • Section 1: Project Ovenriew • Section 2: Conditions and Requirements Summary � Section 3: Offsite Analysis • Section 4: Flow Control and Water Quality Facility Analysis and Design • Section 5: Conveyance System Analysis and Design • Section 6: Special Reports and Studies • Section 7: Other Permits • Section 8: CSWPPP Analysis and Design • Section 9: Bond Quantities, Facility Summaries, and Declaration of Covenant • Section 10: Operations and Maintenance Manual � ' � City of Renton TECHNICAL INFORMATION REPORT (TIR) WORKSHEET � Part 1 PROJECT OWNER AND Part 2 PROJECT LOCATION AND PROJECT ENGINEER DESCRIPTION 'i Project Owner: KRRV Development, LLC Project Name: NE 7th Short Plats II Address: P.O. Box 908 ' Ravensdale,WA 98051 Location ' Phone: (425) 432-5932 Township: 23 North Project Engineer: Darrell Offe, P.E. Range: 5 East Company: Offe Engineers, PLLC Section: 10 Address/Phone: 13932 SE 159th Place Renton, WA 98058 425 260-3412 Part 3 TYPE OF PERMIT Part 4 OTHER REVIEWS AND PERMITS APPLICATION Subdivision ❑ DFW HPA _ Shoreline Management , X Short Subdivision ❑ COE 404 Rockery ❑ Grading ❑ DOE Dam Safety Structural Vaults ❑ Commercial ❑ FEMA Floodplain ❑ Other ❑ Other ❑ COE Wetlands Part 5 SITE COMMUNITY AND DRAINAGE BASIN Community Narth Renton Drainage Basin Maplewood Creek/ Cedar River/ Lake Washington Part 6 SITE CHARACTERISTICS ❑ River '� Floodplain � Seeps/Springs ❑ Stream � High Groundwater Table ❑ Critical Stream Reach � Groundwater Recharge ❑ Depressions/Swales i �ther ❑ Lake ❑ Steep Slopes i Part 7 SOILS Soil Type Slopes Erosion Potential Erosive Velocities Qgt 5— 10% minor ❑ Additional Sheets Attached Part 8 DEVELOPMENT LIMITATIONS REFERENCE LIMITATION/SITE CONSTRAINT ❑ Ch. 4—Downstream Analvsis Restrictive Covenant ❑ Limited Infiltration Design � J J � � ❑ Additional Sheets Attached Part 9 ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS I DURING CONSTRUCTION AFTER CONSTRUCTION ❑ Sedimentation Facilities ❑ Stabilize Exposed Surface ❑ Stabilized Construction Entrance ❑ Remove and Restore Temporary ESC Facilities ❑ Perimeter Runoff Control ❑ Clean and Remove All Silt and Debris � ❑ Clearing and Grading Restrictions ❑ Ensure Operation of Permanent Facilities ❑ Cover Practices ❑ Flag Limits of SAO and open space ❑ Construction Sequence preservation areas ❑ Other ❑ Other . � Part 10 SURFACE WATER SYSTEM X Tank X Infiltration Method of Analysis ❑ Grass Lined Vauit Channel ❑ Depression 2009 City of Renton ❑ Pipe System � Energy Dissipater � Flow Dispersal KCRTS ❑ Open Channel G Wetland � Waiver Compensation/Mitigati ' ' Stream on of Eliminated Site ❑ Dry Pond J ❑ Regional Storage Detention Brief Description of System Operation: Catch basins within curb line of street, conveyance to existing City system downstream, limited infiltration on lots for house. Facility Related Site Limitations �, Reference Facility Limitation I Part 11 STRUCTURAL ANALYSIS Part 12 EASEMENTS/TRACTS Cast in Place Vault X Drainage Easement ❑ Retaining Wall ❑ X Access Easement Rockery >4' High ❑ Structural on Steep Slope Tract ❑ Other ❑ Other Part 13 SIGNATURE OF PROFESSIONAL ENGINEER I or a civil engineer under my supervision my supervision have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attachments. To the best of my knowledge the information provided here is accurate. � �l Signed/Dat r � I Section 1: Project Overview The proposal is to create twelve individual single family lots from 3 separate short plats in the Renton Highlands near the Renton Vocational College. The property addresses are: 3513, 3517, and 3603 NE 7�' Street. These three short plats have been preliminary approved through the City of Renton. The reasoning to combine the three for engineering construction plan approval is to allow for the simplicity of construction of the utilities under one construction permit. The existing residences, impervious areas, and out buildings on the property are currently being removed under a separate demolition permit. These structures will be removed prior to the start of the utility construction. The project area including all three pieces is 83,232 square feet (1.91 acres). The existing King County Tax Parcel number is 801110-0130, -0120, & 0110. There are no sensitive areas on the project site. The property has a gentle slope of approximately 4% towards the southwest corner of the property. The soils on the site have been identified by a Geotechnical Engineers as'�glacial consolidated till"(Qgt). These soils are not suitable for Full Infiltration of storm water runoff. The soil logs indicate moist silty sands with no ground water within the holes at 4'. The proposal for storm water treatment for the project is: (A) provided "limited infiltration systems"for the proposed houses and driveways; (B) provide a storm water treatment vault for the access road and runoff from the new houses; (C) record a "Restrictive Covenant" limiting the amount of impervious area to be allowed on the new lots. The proposal is to combine three separate short plats into one storm water facility located on the westerly short plat. The facility will be sized for these three short plats for detention and water quality treatment. f . Section 2: Conditions and Requirements Summary 2009 City of Renton Drainage Manual C.�.3 LIVLITED INFILTR.A"I�I01�r w C.2.3 LIMITED INFILTRATION Limited infiltration is the use of infiltrarion devices from Section C.2.2 in soils that are not as permeable as the medium sands or coarse sands/cobbles targeted for full infiltration in Section C.2.2. These less desirable soils include fine sands, loamy sands,sandy loams,and loams,which tend to be more variable in permeability,more frequently saturated during the wet season,and more prone to plugging over tune. While full infiltration may be possible under the best of these soil conditions, in the long rnn,these condirions will conspire to limit average infiltration capacity to something much less than that of full infiltration. Therefore,using limited infiltration as specified in this section will not be credited the same as using full infiltration as specified in Section C.2.2. Applicable Surfaces Limited infiltration may be applied to any impervious surface (e.g., roof. drive���ay, parking area,or road) subject to the minimum requirements and design specifications in this section. Operation and Maintenance See Section C.23.5(p.C-50). C.2.3.1 REQUIRED SOILS REPORT In order to properly design limited infiltration devices, a soils report is required to identify the de.pth to impermeable layers(i.e.,hardpan)and to the ma�cimum wet season groundwater level. See Section C.2.2.1 (p.C-41)for more details on this report. In many cases,this report will have akeady been prepared as required in Sections C.13.1 and C.13.2 for lots where full dispersion is not feasible or applicable to target impervious surface per Section C.2.1. C.2.3.2 MINIMUM DESIGN REQUIREMENTS FOR LIMITED INFILTRATION The minimum requirements for limited infiltration are the same as those for full infiltration,except infiltration depressions aze excluded and existing soils in the location of the infiltration device may be fine sands,loamy sands,sandy loams,or loams as opposed to only medium sands or better. Note that gravel and medium sand soils used for full inftltration correspond to Soil Types lA, IB, 2A and 2B in the Soil Teztural Classifcation system used for onsite septic system design;fine sands are Type 3;and loamy sands, sandy loams and loams are Type 4 soils. Silt and clay loams, and cemented till(hardpan)are not suitable for limited infiltration systems. C.2.3.3 USE OF GRAVEL FILLED TRENCHES FOR LIMITED INFILTRATION The specifications for use of gravel filled trenches for limited infiltration are the same as those used for full infiltration,except that every 1,000 square feet of tributary impervious surface requires different trench lengths as follows:(a�75 feet if the soil is a fine sand/loamy sand,(b) 125 feet if the soil is a sandy loam,or(c) 190 feet if t�ie soil is a loam. C.2.3.4 USE OF DRYWELLS FOR LIMITED INFILTRATION The specificarions for use of drywells for limited infiltration are the same as those used for full infiltration, except that every 1,000 square feet of tributary impervious surface requires different gravel volumes as follows:(a)230 cubic feet if the soil is a fine sand/loamy sand,(b)380 cubic feet if the soil is a sandy loam,or(c)570 cubic feet if the soil is a loam. 'U09 Surface��'a�er De;ign'��lanual-Appendis C 1 �� =i�(14 � (�-�9 SECTION�C.2 FLOW CONTROL BMPs M C.2.3.5 MAINTENANCE INSTRUCTIONS FOR LIMITED INFILTRATION If the limited infiltration flow control BMP is proposed for a project,the following maintenance and operation instructions must be recorded as an attachment to the required declaration of covenant and grant of easement per Requirement 3 of Section C.13.3 (p.C-18). The intent of these instructions is to explain to future property owners,the purpose of the BMI'and how it must be maintained and operated. These instructions are intended to be a minimum;DDES may require additional instructions based on site- specific conditions. Also,as the County gains more experience with the maintenance and operation of these BMPs,future updates to the instrucrions will be posted on King County's Surface Water Design Manual website. ❑ TEXT OF INSTRUCTIONS Your property contains a stormwater management flow control BMP (best management practice)called "limited infiltration,"which was installed to mitigate the stormwater quantity and quality impacts of some or all of the impenrious surfaces on your property. Limited infiltration is a method of soaking runoff from impervious area(such as paved areas and roofs)into the ground. Infiltration devices, such as gravel filled trenches, drywells,and ground surface depressions,facilitate this process by putting runoff in direct contact with the soil and holding the runoff long enough to soak most of it into the ground. To be successful,the soil condition around the infiltration device must be able to soak water into the ground for a reasonable number of years. The infiltration devices used on your property include the following as indicated on the flow control BMP site plan: ❑ gravel fitled trenches, ❑drywells. The size, placement,and composition of these devices as depicted by the flow control BMP site plan and design details must be maintained and may not be changed without written approval either from the King County Water and Land Resources Division or through a future development permit from King County. Infiltrati�n devices must be inspected annualty and after major storm events to identify and repair any physical defects. Maintenance and operation of the system should focus on ensuring the system's viabiliry by preventing sediment-laden flows from entering the de�ice. Excessive sedimentation will result in a plugged or non-func6ioning facility. If the infiltration device has a catch basin, sediment accumulation must be removed on a yearly basis or more frequently if necessary. Prolonged ponding around or atop a device may indicate a plugged facility. If the device becomes plugged, it must be replaced. Keeping the areas that drain to infiltration devices well swept and clean will enhance the lor .��. - . . _ s�,-, p.,.♦ ..i { ,u� �;Ii ��a .-i ..,.,��} i�ia� . i�.;__ .� _, . � . . � .3. .:-. . ._ _ . .. _ .,_ -.� _ ... ._ i 7;_���: _, , ��,�.a�c ��.i[.� v:.;��i:.i�u�ua: ;�p}��:tu..�� C-50 SECTIOi�C.2 FLOVb'CONTROL Bh1Ps other types of soils or fill materials if designed by a civil engineer in accordance with the infiltration faciliry standards in Section 5.4 of the SWDM. b) For purposes of determining whether full infiltration of roof runoff is mandatory as outlined in Secrion C.13,the depth of soil to the ma�cimum wet season water table or hardpan must be at least 3 feet. For any optional or mandatory application of full infil ion,the depth of soil to the aximum wet season water table or hardpan must be at least 1 f below the bottom of a gravel ed infiltration system and at least 3 feet below the bottom round surface depression used fo 11 infiltration. 2. For purp es of deternuning whether full infiltration of ro runoff is mandator}-as outlined in Section C. ,one of the following infiltration devic ust be used in accordance with the design specificario or each device set forth in Sections .23,C.2.2.4,and C.2.2.5. Note:full infiltration may be possib using other types and sizes of in ation devices if designed by a civil engineer in accordance wit e inftltration faciliry stand in Section S.4 of the SWDM. • Gravel filled nches(see Section .23,p.C-42) • Drywells(see Se 'on C.2.2.4,p. 3) • Ground surface de essions ee Section C.2.2.5,p.C-43) 3. A minimum 5-foot setback � be maintained between any part of an infiltration device and any structure or property line. r setbacks from structures may be specified in the design specifications for each in ati device. Infiltration devices may not be placed in sensitive area buffers. A 50-foot set is req d between an infiltrarion device and a steep slope hazard area or landslide hazard ar this may be uced if approved by a geotechnical engineer or engineering geolagist and DD �, 4. Infiltration de�' s are not allowed in criti azea buffers or on slopes steeper than 25%(4 horizontal to 1 vertical nfiltration devices proposed lopes steeper than 15%or within 50 feet of a landslide zard area or steep slope hazard ar must be approved by a geotechnical engineer or enginee g geologist unless otherwise approved the DDES staff geologist. 5. For with septic systems,infiltration devices mus located downgradient of the primary and re e drainfield areas. DDES pernut review staff can ' e this requirement if site topography arly prohibits subsurface flows from intersecting the dr ' d. 6 e infiltration of runoffmust not create flooding or erosion im ts as determined by DDES. If runoff is infiltrated near a landslide hazard area,erosion hazard area,steep slope hazard area,or a slope steeper than 15%,DDES may require evaluation and approval of the proposal by a geotechnical engineer or engineering geologist. �� ��� D C.2.2.3 USE OF GRAVEL FILLED TRENCHES FOR iriii�.L INFILTRATION Gravel filled trenches(also called"infiltration trenehes")are a good option where the depth to the maximum wet-season water table or hazdpan is between 3 and 6 feet. Figure C.2.2.A(p.C�15)and Figure C.2.2.B(p. C-46)illustrate the specifications for gravel filled trench systems as outlined below: �i�/,� , ) . obbles, infiltration tre in length per �'�Z�p��- 1,000 square feet ' ' ocated in medium sands,infiltration trenches � 0 feet in length per 1,000 square feet o � ace served. G �2 .3• � 2. Maximum trench length must not exceed 100 feet from the inlet sump. 3. The trench width must be a minunum of 2 feet. 4. The trench must be filled with at least 18 inches of 3/4-inch to 11/Z-inch washed drain rock. The drain rock may be covered with backfill material as shown in Figure C.2.2.A or remain exposed at least 6 inches below the lowest surrounding ground surface as shown in Figure C.2.2.B. 1/9/2009 2009 Surface Water Design Manual—Appendix C C-42 SECTION,C.2 FLOW CONTROL BMPs 3. The depression overflow point must be at least 6 inches below any adjacent pavement area and must be situated so that overflow does not cause erosion damage or unplanned inundation. 4. The depression side slopes must be no steeper than 3 horizontal to 1 vertical. 5. Spacing between multiple infiltration depressions shall be a minimum of 4 feet. �` A b--I�3�Y�i'El�2Sii'�TfC'S92e�C'gCN7'tCI�fl��e(1S� r,�f..Pt frpm hnil�i •;a�- - ----� r haC 111211f /v %A po . f 7. Infiltration depressions may be any size or shape provided the above specifications and the minimum requirements in Section C.2.2.1 are met. 8. The ground surface of the infiltration depression must be vegetated with grass or other dense ground cover. C.2.2.6 MAINTENANCE INSTRUCTIONS FOR FULL INFILTRATION the full infiltration flow control BMI'is proposed for a project,the fo ing maintenance and operation '� i uctions must be recarded as an attachment to the required decla 'on of covenant and grant of ea ent per Requirement 3 of Section C.13.3(p.G18). The ' t ofthese instructions is to explain to futur roperty owners,the purpose of the BMP and how it mu e maintained and operated. These instruc ns are intended to be a minimum;DDES may requi additional instructions based on site- ��/� � specific c ditions. Alsq as the County gains more expe ' ce with the maintenance and operation of ��� O these BMPs, ture updates to the instructions will be ed on King County's Surface Water Design lManual websi n '�0 TEXT OF INST CTIONS . t/•''! GYour property contains stormwater manag ent flow control BMP(best management practice)called "full infiltration,"which w installed to miti e the stormwater quantity and quality impacts of some or all of the impervious surfaces your prop . Full inflltration is a method of soaking runoff from impervious area(such as paved areas a roofs) ' o the ground. If properly installed and maintained,full infiltration can manage runoff so that a m ri f precipitation events are absorbed. Infiltration devices, such as gravel filled trenches, drywells, a round surFace depressions,facilitate this process by putting runoff in direct contact with the soil and di the runoff long enough to soak most of it into the ground. To be successful,the soil condition und t infiltration device must be reliably able to soak water into the ground for a reasonable nu er of year ', The infiltration devices ed on your prop indude the following as indicated on the flow control BMP site plan: ❑ gravel fille renches, ❑ drywells, ground surface depressions. The size, placement,and ' composition of these vices as depicted by the ow control BMP site plan and design details must be � maintained and m ot be changed without writt approval either from the King County Water and Land � Resources Divisi or through a future developmen ermit from King County. ', Infiltration devi s must be inspected annually and afte ajor storm events to identify and repair any physical def s. Maintenance and aperation of the syst should focus on ensuring the system's viability I by prevenf sediment-taden flows from entering the de�i Excessive sedimentation will result in a I plugged non-functioning facility. If the infiltration device ha catch basin,sediment accumulation must be rem ed on a yearly basis or more frequently if necessary. P onged ponding around or atop a device may i icate a plugged faality. If the device becomes plugged, it m t be replaced. Keeping the areas that ain to infiltration devices well swept and Gean will enhance the gevity of these devices. For roofs, fr ent Geaning of gutters will�educe sediment loads to these devices. 1/9/2009 2009 Surface Water Design Manuat—Appendix C C-44 � C.2.2 FULL INFILTR ATION FIGURE C.2.2.A TYPICAL TRENCH INFILTRATION SYSTEM � I t roof � �drain ' PLAN VIEW � NTS �4"rigid or 6"flexible i � pertorated pipe � % j-------------------------•--------....__.��.. _ / � � �/ i ---------•--- - -- ...--------- ` infiltration trench �� —sump w/so�id lid PLAN VIEW roof drain NTS � � overflow —�` 4"rigid or 6"flexible splash bloc[c��,J I �perforated pipe � � ,���:�.: hi�i�%Ii; ;i ii;�����y;���;i�j��%��%�i% �_ ��.:�' 6" � y,�,i,i i..i, �' .---�------�--..•--•-----------•--------------- _ o � 6^ `oG , ---- eve-- „i '�=� =�_ washed rock `� J°� ��� r .��+.1'm� 5.0'min 12 I ~ 1 1/2"-3/4" �" �"' G�n�V�� J ,1'mm F 1—____ , . �------ --------------------=_�-°-'�-----'Y I � fine mE � . , crronn i V21"12" �i'' ;� 1 I , compacted backfill 1 .�� 6" ya 4 ,i �— u - � 4"rigid or 6"flexible �Vo � � �,�� � c� perforated pipe 24" / �'"o �4�� � �i �'� '�° �fl�" washed rock 12" T � , � �°°o oG� ��'� 1 1/2"-314„ i. - � _.�r,7 �� c`. /{\`���t���"�v�� ,�l.��/\���/\��\�/. �—24"—� �SECTION A NTS 2U09 Surface R'ater Design Manual-Appendix C 1/9/2009 C-45 . Section 3: Offsite Analysis The downstream system was walked on Aprit 19th, 2013. The site drainage currently sheet flows across the property to the west and eventually entering the City storm system in NE 7"' Place. The proposed development is to convey the drainage form the site into NE 7th Street and then to the west into the City storm system at Newport Court NE and NE 7th Street. This point of inflow is approximately 500 feet above the current sheet flow point. The drainage system is completely tight lined from Newport Court NE/ NE 7"' Street through the City storm piping to an apartment site, Hilltop Homes Apartments downstream. The network of pipes runs 810 feet to a storm water pond within the Hilltop Apartments. The storm pipe system was visually inspected in three locations downstream; at CB #113111, CB #113118, and CB #113041. These are City of Renton storm water codes for City catch basins. The system of pipes were 12"concrete entering into Type II catch basins. There appeared to be no overtopping of the basins or capacity issues. The roadway area above these catch basins had no indication of overtlow. The storm water enters into a pond within Hilltop Apartments, City node #145531. This pond is heavily over grown with trees and blackberries. A walk of the parameter of the pond shows no signs of overtopping or erosion. The parking lot to the south of the pond is about 4' below the pond berm. There were no signs of overtopping in this area either. The drainage leaves the pond and enters into Monroe Avenue NE about 200 feet north of NE 4"' Street. The storm system is within the centerline of the road and was not inspected. The storm system continues to the south in Monroe Ave until it enters the City Shop Area at NE 2th Street. E5NE - 09 T23N R05E NE 114 - Pg. 46 S�°� „I- . . ..:� Z g�p1 85, u - ,- �_. � .�.Z, �, . E9� �31t . 7 �__�\ . 55 �d J Z 85��' - 651. 17 �� . . : - r .-._.... . Cw - . . 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P - --�..newe� i s - �n4i� • .�t O m " ' ' _- i 1 �,.t � Lc Q .5 K- �----e_11�- .__. � Rc, % ----� ,I 4 . -�Y.�7��714,aiCa ., . - _-_- � C,ii:�_-. .- - --- �S, .n 147421 .r��c i� C --- - --1; -0 p ' i3°.it7 �` � -.. .. c� .. -- .. :... ---- - -_ �_-�4. � _ ..�,. � �r,..r1.VS7?5_� 1��eE��.. i UPSTREAM AREA - FLOW THROUGH VAULT ��?�;��r`���� ���:�-�� � xl : �.�� _ Area ?J Till Forest �•90 acres Tili Pasture 0.00 acres Till Grass 0.00 acres Outwash Forest 0.00 acres Ouiwash Pasture 0.00 acres' Ouiwash Grass 0.00 acres Wetland 0.00 acres Impervious 0.00 acres Total 0.90 acres Scale Factor: 1.00 Hourly Reduced Time Series: Upstream Basin - Forested » Compute Time Series I Modity User Input , __ _ ___ __ _ _ -- --- ____...— --------____ File for computed Time Series [TSFJ � ��. - � � � ��� �. ' t ,. _,,� .t�=.'�.< < . _ f � Flaw Frequency Analysis i ' -------------------------------------------------------- Time Series File:upstream basin - forested. tsf Praject I.ocation:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis--------- Flow Rate Rank Time of Peak - - Peaks - - P.ank Return Prab (CFS} (CFS} Period 0.057 2 2i09i01 18:00 0 .073 1 100.00 0.990 0.015 7 1i06i02 3 :00 0.057 2 25.00 0 .960 0. 042 4 2i28iO3 3:00 0.044 3 10.00 0.900 0.002 8 3i24iO4 21 :00 0.042 4 5.00 0.300 0. 025 6 1i05i05 5 :00 0 . 036 5 3.00 0 .667 0.044 3 1i18/06 21 :00 0 .025 6 2.00 0.500 0.036 5 11i24i06 4 :00 0 .015 7 1 .30 0.231 0.073 1 1i09i08 9 :f0 0 . 002 8 1 . 10 0 . 091 I Computed Fe.�b;s D . 067 50.00 0. 9$0 � I �� � !r: I, ; II Section 4: Flow Control and Water Quality Facility Analysis and Design Flow control/water quality preliminary calculations determined the projects will require a facility sized for both detention and water quality. The projects (the combined three short plats) will have a restrictive covenant limiting the impervious areas on the developed lots to 2,600 square feet with "limited infiltration"dry wells for 1,300 sq. feet of the proposed impervious areas. The balance of the property will then be collected and conveyed into the storm facility located on the west short plat. The facility will be sized for all three short plats. The detention/water quality facility is located on the westerly short plat in the southwest corner. The calculations attached are used to size the facility. Additional upstream flows, from property to the east, flow through the project and are accounted for within the vault as "pass through"flows. A storm stub has been provided in the southeast corner of the easterly short plat to connect the easterly upstream area when developed. NE 7th West Short P/at Area Breakdown Impervious Pervious Forest Area Breakdown Tota/Areas s , feet s , feet s , feet Property west/middle 57307 ' east 18653 ' frontage 4305 90265 Lots 12 15600 15600 2,600 sq. ft. impervious max. (SO%) I (31,200 sq. ft. max.) "Limited In�/tration" �I Landscaping 4050i ' Roads 20'roadsecrion (west/middle) 1i419 �, (Fire Lane) 20' (east) 2840 ' Frontage 287 4305 Z296 2009 (sidewalk one side) 5' (3' widening) 3' I Tota/Area Im pervious 32155 Pervious 58110 Forest O Total Area 90265 Input Parameters Tota/Area 2.07 acres Impervious 0,74 acres Pervious 1.33 acres i � ,� I i i � � , I . � Pedeveloped Conditions � Land U_e�ummar,� i �=7 i j o { O ��,.� Area- .__ - - ?; Till For�st �.97 acres Till Pas#ure O.aa acres Tiil Grass 0.00 acres" Ouiwash Forest Q.QO acres Ouiwash Pasture �•0� acres Ouiwash Grass O.UO acres' Wetiand U.OU �cres , Impervious d.00 acres I - - _ I Total _ _ I 2.97 acres I�� _ ___---------- - I Scale Factor: 1.00 Hnurly Reduced ' Time Series:�Predev.ts� }>� I Compu#e Time Series � . . Modif�User lnput _- ___ _ _ __ _ - � --__--_�.__-----__.._____.___ __------------- ------_ _.-,-__. . __ ___________ File for computed Time Sene$ [.TSFj 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 0.188 2 2/09/O1 18:00 0.239 1 100.00 0.990 0.051 7 1/06/02 3:00 0.188 2 25.00 0.960 Q.139 4 2/28/03 3:00 0.144 3 10.00 0.900 C.005 8 3/24/04 20:00 0.139 9 5.00 0.800 C.082 6 1/OS/OS 8:00 0.121 5 3.00 0.667 0.144 3 1/18/06 21:00 0.082 6 2.00 0.500 0.121 5 11/24/06 4:00 0.051 7 1.30 0_231 s 0.239 1 1/09/08 9:00 0.005 8 1.10 0.091 Computed Peaks 0.222 5�.00 0.980 Developed Conditions `� Lan�Use Summary __=� � �_o i t� ��.5� Area ?� Till Forest 0.9U acres Till Pasture 0.00 acres Till Grass 1.33 acres Qutwash Foresf 0.00 acres Outwash Pasture 0.00 acres Ouiwash Grass 0.00 acres tNetland 0.00 acres Impervious 0.74 acres Total 2.97 acres —__ _____ ._____ Scale Factor: 1.OU Hourly Reduced Time Series: iDev.ts� »� , Compute Time Series ' Modiiy User Inpu# � _ _ _ . _-- _ _ _ _ __ _. _--- - File for computed Time Series [.TSF] 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 0.334 9 2/09/O1 2:00 0.695 1 100.00 0.990 0.233 7 1/O5/02 16:00 0.401 2 25.00 0.560 0.901 2 2/27/03 7:00 0.354 3 10.00 0.900 0.209 8 8/26/04 2:00 0.339 4 5.00 0.800 0.258 6 10/28/04 16:00 0.327 5 3.00 0.667 0.354 3 1/18/06 16:00 0.258 6 2.00 0.500 0.327 5 11/24/06 3:00 0.233 7 1.30 0.231 0.695 1 1/09/08 6:00 0.209 8 1.10 0.091 Computed Peaks 0.597 50.00 0.980 Detention Faciliiv Desiqn Retention/Detention Facility Type of Facility: Detention Vault Facility Length: 72.00 ft Facility width: 24.00 ft Facility Area: 1728. sq. ft Effective Storage Depth: 10.50 ft Stage 0 Elevation: 100.00 ft Storage Volume: 18144. cu. ft Riser Head: 10.50 ft Riser Diameter: 12.00 inches Number of orifices: 3 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 0.75 0.049 2 6.00 1.25 0.087 4.0 3 7.20 0.75 0.027 4.0 Top Notch Weir: None Outflow Rating Curve: None Sta e Elevation Stora e Dischar e Percolation q 4 9 (ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs) o.ao ioo.00 o. o.000 o.oao o.00 o.oi ioo.oi v. o.000 o.oai o.00 0.02 100.02 35. 0.001 0.002 0.00 0.03 100.03 52. 0.001 0.003 0.00 0.09 100.04 69. 0.002 0.003 0.00 0.05 100.05 86. 0.002 0.004 0.00 0.06 100.06 104. 0.002 0.004 0.00 0.27 100.27 467. 0.011 0.006 0.00 0.47 100.47 812. 0.019 0.011 0.00 0.68 100.68 1175. 0.027 0.013 0.00 0.89 100.89 1538. 0.035 0.019 0.00 1.09 101.09 1884. 0.093 0.016 0.00 1.30 101.30 2246. 0.052 0.017 0.00 1.50 101.50 2592. 0.060 0.019 0.00 1.71 101.71 2955. 0.068 0.020 0.00 1.92 101.92 3318. 0.076 0.021 0.00 2.12 102.12 3663. 0.084 0.022 0.00 2.33 102.33 4026. 0.092 0.023 0.00 2.53 102.53 4372. 0.100 0.024 0.00 2.74 102.74 9735. 0.109 0.025 0.00 2.99 102.94 5080. 0.117 0.026 0.00 3.15 103.15 5443. 0.125 0.027 0.00 3.36 103.36 5806. 0.133 0.028 0.00 3.56 103.56 6152. 0.191 0.029 0.00 3.77 103.77 6515. 0.150 0.030 0.00 3.97 103.97 6860. 0.157 0.030 0.00 4.18 104.18 7223. 0.166 0.031 0.00 4.39 104.39 7586. 0.174 0.032 0.00 4.59 104.59 7932. 0.182 0.033 0.00 4.80 104.80 8299. 0.190 0.033 0.00 5.00 105.00 8690. 0.198 0.034 0.00 5.21 105.21 9003. 0.207 0.035 0.00 5.42 105.92 9366. 0.215 0.036 0.00 � 5.62 105.62 9711. 0.223 0.036 0.00 5.83 105.83 10074. 0.231 0.037 O.00 6.00 106.00 10368. 0.238 0.037 0.00 6.G1 106.01 10385. 0.238 0.038 0.00 6.03 106.03 10920. 0.239 0.039 0.00 6.04 106.04 10437. 0.240 0.040 0.00 6.05 106.05 10454. 0.240 0.043 0.00 6.07 106.07 10469. 0.241 0.046 0.00 6.06 106.06 10506. 0.241 0.049 0.00 6.09 106.09 10529. 0.292 0.050 0.00 6.10 106.10 10541. 0.292 0.051 0.00 6.31 106.31 10909. 0.250 0.062 0.00 i � � � 6.52 106.52 11267_ 0.259 0.069 0.00 6.72 106.72 11612. 0.267 0.076 0.00 6.93 106.93 11975. 0.275 0.081 0.00 i 7.13 107.13 12321. 0.283 0.086 0.00 I 7.20 107.20 12492. 0.286 0.087 0.00 7.21 107.21 12459. 0.286 0.088 0.00 � 7.22 107.22 12476. 0.286 0.089 0.00 � 7.23 107.23 12493. 0.267 0.090 0.00 � 7.24 107.24 12511. 0.287 0.091 0.00 7.25 107.25 12528. 0.288 0.092 0.00 7.26 107.26 12595. 0.288 0.093 0.00 7.47 107.47 12908. 0.296 0.101 0.00 ' 7.67 107.67 13254. 0.304 0.108 0.00 ' 7_88 107_88 13617_ 0.313 0_114 0.00 8.09 108.09 13980. 0.321 0.119 0.00 8.29 108.29 14325. 0.329 0.124 0.00 � 8.50 108.50 14688. 0.337 0.129 0.00 i 8.70 108.70 15034. 0.345 0.133 0.00 '� 8.91 108.91 15396. 0.353 0.138 O.QO ', 9.12 109.12 15759. 0.362 0.192 0.00 ' 9.32 109.32 16105. 0.370 0.146 0.00 ' 9.53 109.53 16468. 0.378 0.150 0.00 9.73 109.73 16813. 0.386 0.154 0.00 9.94 109.99 17176. 0.394 0.157 0.00 �, 1Q.14 110.14 17522. 0.402 0.161 0.00 ' 10.35 110.35 17885. 0.411 0.165 0.00 I 10.50 110.50 18144. 0.417 0.167 0.00 10.60 110.60 18317. 0.420 0.477 0.00 10.70 110.70 18490. 0.424 1.090 0.00 � 10.80 110.80 18662. 0.428 1.770 0.00 � 10.90 110.90 18835. 0.432 2.570 0.00 11.00 111.00 19008. 0.436 2.650 0.00 I 11.10 111.10 19181. 0.440 3.110 0.00 I 11.20 111.20 19354. 0.444 3.340 0.00 11.30 111.30 19526. 0.498 3.560 0.00 11.40 111.90 19699. 0.452 3.770 0.00 11.50 111.50 19872. 0.456 3.960 0.00 11.60 111.60 20045. 0.460 4.150 0.00 11.70 111.70 2C218. 0.464 4.330 0.00 11.80 111.80 20390. 0.468 4.500 0.00 11.90 111.90 20563. 0.472 4.660 0.00 12.00 112.00 20736. 0.476 4.820 0.00 12.10 112.10 20909. 0.480 4.980 0.00 12.20 112.20 21082. 0.484 5.120 0.00 12.30 112.30 21254. 0.488 5.270 0.00 12.40 112.40 21427. 0.492 5.410 0.00 �d Inflow Outflow Peak Storage Target Calc Stage Elev (Cu-Ft) (Ac-Ft) 0.70 0.29 0.59 10.62 110.62 18351. 0.921 2 0.33 ******* 0.20 10.51 110.51 18163. 0.417 3 0.33 ******* 0.12 8.30 108.30 14347. 0.329 9 0.35 ******* 0.11 7.64 107.64 13209. 0.303 5 0.40 ******* 0.12 8.30 108.30 14341. 0.329 6 0.21 ******* 0.06 6.33 106.33 10995. 0.251 7 0.23 ******* 0.04 5.29 105.29 9139. 0.210 8 0.21 ******* 0.02 2.29 102.29 3955. 0.a91 ---------------------------------- Route Time Series through Facility Inflow Time Series File:dev.tsf Outflow Time Series File:RDOut Inflow/Outflow Analysis Peak Inflow Discharge: 0.695 CFS at 6:00 on Jan 9 in Yea= 8 Peak Out£low Discharge: 0.590 CE'S at 9:00 on Jan 9 in Year 8 Peak Reserooir Stage: 10.62 Ft Peak Reservoir Elev: 110.62 Ft Peak 2eservoir Storage: 18351. Cu-Ft . 0.421 Ac-Ft Duration Comparison Anaylsis Base File: predev.tsf New File: rdout.tsf Cutoff Units: Discharge in CFS -----Fraction of Time----- ---------Check of Tolerance------- Cutoff Base New %Change Probability Base New °sChange � O.C41 � 0.95E-02 0.82E-02 -13.8 I 0.95E-02 0.041 0.037 -8.8 0.052 I 0.64E-02 0.70E-02 10.0 � 0.64E-02 0.052 0.055 4.8 0.063 I 0.49E-02 0.45E-02 -9.2 I 0.49E-02 0.063 0.061 -3.1 0.075 I 0.37E-02 0.36E-02 -9.0 � 0.37E-02 0.075 0.072 -3.3 0.086 I 0.29E-02 0.28E-02 -2.3 � 0.29E-�2 0.086 0.085 -1.1 0.097 I 0.22E-02 0.24E-02 7.4 � 0.22E-02 0.097 0.101 3.8 � 0.108 � 0.15E-02 0.18E-02 20.0 ( 0.15E-02 0.108 0.119 5.0 /�� 0.120 I O.10E-02 O.10E-02 -1.6 � O.10E-02 0.120 0.119 -0.6 0.131 � 0.62E-03 0.64E-03 2.6 I 0.62E-03 Q_131 0.132 1.1 0.192 � 0.34E-03 O.S1E-03 47.6 I 0.34E-03 0.142 0.148 3.7 0.154 � 0.21E-03 0.28E-03 30.8 I 0.21E-03 0.154 0.158 3.0 0.165 I 0.16E-03 0.98E-04 -40.0 I 0.16E-03 0.165 0.162 -1.9 0.176 I 0.98E-04 0.16E-04 -83.3 I 0.98E-09 0.176 0.166 -6.0 0.187 � 0.16E-04 0.16E-04 0.0 � 0.16E-09 0.187 0.200 7.0 Maximum positive excursion = 0.015 cfs ( B.9�) � occurring at 0.185 cfs on the Base Data:predev.tsf and at 0.200 cfs on the New Data:rdout.tsf Maximum negative excursion = 0.005 cfs (-10.9o} � occurring at 0.042 cfs on the Base Data:predev.tsf and at 0.037 cfs on the New Data:rdout.tsf E.F�,:d-cs4,..,�er...w.n.crz . . ._ . � . - � . . .. . . . . � � ,.`-:- �, I' o I �Tu'gn.3vt ♦ • -,___' i � .__. . .__ _.r-_.+.._ . ._._._ . ___... ...____ .._....-. I�I ^ R ..._..-...-._ ,___ _____�'R � o w, . �' " • �` U � c _ a '-.� - p GOO ......... .. . . ( 4 •� � O O I •{- * I �� I o � c I I - c � �- , . . . . . � � , , . . . .. . . . . , � � . , � � �r� 50� �70, 10-� SO�� iG��� 10`. I P�eotskd.ry CYrcrceRcc � � Wetpool Sizing Calculations Per 2009 King County Stormwater Management Manua{ Project Name: NE 7th Short Plats (all three projects) Project Number: Facility Description: Water Qualiry Sizina Step 1: Identify required wetpool volume factor(f). f= 3 Per KCSWDM 6.4.1.1 Step 2: Determine rainfall (R)for the mean annual storm. R= Q.4�7 Per KCSWDM Fig. 6.4.1.A Step 3: Calculate runoff from the mean annual storm (V,) for the developed site. V�_ (0.9A; + 0.25,4t9+ 0.10A�+ 0.01Ao)x(R/ 12) where: A; = Impenrious Surface Area = 32;155 s.f. A�9 =Till Grass Area = 58,110 s.f. A� =Till Forest Area = 0 s.f. Ao = Outwash Area = 0 s.f. V�= 1,702 C.f. Step 4: Calculate required wetpool volume (Vb). Vb= f xV� Vb= 5,107 c.f. , � CONVEYENCE CALCULATIONS STORMWATER CONVEYANCE BACKWATER CALC[/L4 TION SHEET _ (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) Barrel Entrance Entrance . Pipe 100 year Pipe Outlet Inlet Barrel Barrel Velocity TW Friction HGL Head Segment Q Length Pipe "n" Elev Elev Area Velocity Head Elev Loss Elev Loss CB to CB cfs ft Size Value feet (feet s . feet f s feet feet feet) feet feet #10 - #11 1.15 84 12" 0.012 402.66 403.50 0.79 1.46 0.02 404.00 0.0168 404.02 0.01 #11 - #7 1.15 169 12" 0.012 398.45 402.66 0.79 1.46 0.02 404.15 0.0338 404.18 0.01 #7 - #5 1.15 134 12" 0.012 399.00 398.45 0.79 1.46 0.02 403.31 0.0268 403.34 0.01 #5 - #3 1.15 82 12" 0.012 398.57 399.00 0.79 1.46 0.02 399.10 0.0164 399.12 0.01 #3 -vault 1.15 24 12" 0.012 388.20 398.57 0.79 1.46 0.02 399.65 0.0048 399.65 �.01 #13 - #12 1.15 20 12" 0.015 403.08 403.28 0.79 1.46 0.02 404.00 0.004 404.00 0.01 #12 - #8 1.15 104 12" 0.012 399.38 403.08 0.79 1.46 0.02 403.93 0.0208 403.95 0.01 #8 -vault 1.15 32 12" 0.012 388.20 399.38 0.79 1.46 0.02 403.73 0.0064 403.74 0.01 (14) (15) (16) (17) (18) (19) (20) (21) Exit Outlet Inlet Approach Bend Junction Head Control Control Velocity Head Head HW RIM ELEV Loss Elev Elev Head Loss Loss Elev UPSTREAM feet feet feet feet feet feet feet CB 0.02 404.05 404.15 0 0 0 404.15 408.00 OK.� 0.02 404.22 403.31 0 0 0 403.31 409.70 OK.� 0.02 403.37 399.10 0 0 0 399.10 402.85 OK.� 0.02 399.15 399.65 0 0 0 399.65 402.12 OK.� 0.02 399.69 399.22 0 0 0 399.22 401.27 OK.� 0.02 404.04 403.93 0 0 0 403.93 405.78 OK.� 0.02 403.98 403.73 0 0 0 403.73 405.78 OK.� 0.02 403.77 400.03 0 0 0 400.03 403.38 OK.� (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) Barrel Entrance Entrance - Pipe 100 year Pipe Outlet Inlet Barrel Barrel Velocity TW Friction HGL Head Segment Q Length Pipe "n" Elev Elev Area Velocity Head Elev Loss Elev Loss CB to CB cFs ft Size Value feet feet sq. feet f s) feet feet) (feet feet) feet vault-#2 2.00 57 12" 0.012 386.93 398.00 0.79 2.53 0.04 398.50 0.0114 398.51 0.02 #2 - #1 2.00 58 12" 0.012 386.35 386.93 0.79 2.53 0.04 398.90 0.0116 398.91 0.02 #1 - #14 2.00 149 12" 0.012 380.20 386.35 0.79 2.53 0.04 387.83 0.0298 387.86 0.02 #14 - ex. 2.50 37 12" 0.012 379,46 380.20 0.79 1.46 0.02 387.25 0.0074 387.26 0.01 (14) (15) (16) (17) (18) (19) (20) (21) Exit Outlet Inlet Approach Bend Junction Head Control Control Velocity Head Head HW RIM ELEV Loss Etev Elev Head Loss Loss Elev UPSTREAM feet feet feet feet feet feet feet CB 0.04 398.57 398.90 0 0 0 398.90 401.00 OK.� 0.04 398.97 387.83 0 0 0 387.83 400.00 OK.� 0.04 387.92 387.25 0 0 0 387.25 397.00 OK.� 0.02 387.29 381.10 0 0 0 381.10 383.20 OK.� CONVEYENCE CHECK ?�� .�. � ����-�'�- ��� ��� ������t .�., . Area _ . ?� Till Foresi 0-00 acres Tilt Pasture 1.33 acres Ti11 Grass 0•00 acres Outwash Forest 0.00 acres Outwash Pasture 0.00 acres OutvEash Grass 0.00 acres Wetland 0.00 acres lmpervious 0.74 acres __ ----- Total _ __ 2.07 acres Scale Factor : 1.00 15-Min Reduced Edit Fiow Paths � Time Series: NE 7th Conveyence check �»� Compute Time Series � Modify User Input ` __ . _ _ --_-- ._ ___ . .___ . __ .. ________-___ _ _ ._._ Fite far computed Time Series [.TS� ��,��-���--��` '�.����_ . �.� � � - ._ __ ' -�o)�! �� J ' � � Flov Frequency �nalysis �� � ��� ------------------------------------------ ------------ � �� `�! Time Series File:ne 7th conveyence check.tsf �2r/- �' Froject Location:5ea-Tac ---Annual Peak Flow Rates--- -----Flow F equsncy Analgsis------- Flo;a P.ate Rank Time of Peak - - Peak - - Rank REturn Frob (CFS} Periorl 0.352 6 8�27/O1 18:OU 1.15 1 100.U0 0.990 0.251 8 1/05i02 15:00 83� 2 25.00 0.960 0.832 2 12i�8i02 17:15 0.483 3 10.40 �1.900 0.224 7 8i23iO4 14:30 0.422 4 5.00 0.800 0.401 5 10/28iO4 16:00 0.401 5 3.00 0.667 0.422 9 10i27i05 20:�5 0.352 6 2.d0 0.500 0.4d3 3 10i25/06 22:45 0.284 7 1.30 0.231 1.15 1 1i09/03 6:30 Q.261 3 1.10 0.091 C�_,rnp,:t�d Fea-}:= 1.04 50.00 0.9$0 � � ► . 43.1 CULVERTS—METHODS OF.4NALYSIS FIGURE 4.3.1.B HEADWATER DEPTH FOR SMOOTH INTERIOR PIPE CULVERTS WITH INLET CONTROL 1so 10,000 �ss $,000 EXAMPLE ��� �2� �3� ENTRANCE TYPE s. 156 6,000 0=az incnes (a.o feM). 6, t�=lzocfs SQUARE EDGEWtTH �� 5,000 5' HEADWALL 6. 5. 4,000 H�nr Hw .� 132 0 (feet) 4. + 3,000 ��) z.s a.a 5' 4. 120 �z► z.� �.a � � � 2,000 �a� 2.x �.� 4. I I 108 3. 3. 'D i� feet 96 1,000 3' PLAN ��� GROOVE END WITH 800 __,y ___y HEADWALL H4 Z' Z- �7a: 600 � 500 /� I '��� �2 400 � o Z� � i � = 300 �,�,pj/ = 1 5 � 5 I Zgp V 200 �/ W 1.5 '�r. PLAN �2� — Z � W GROOVE END 0 54 � � Q PROJECTING � ~ 100 � �W Z > 48 / � 80 '� ' _ U = 60 a 1.0 1.0 � �� 42 V w / � 0 50 HW SCALE ENTRANCE � 1.0 � � 40 D TYPE w .9 W 36 � '9 �3� �.• 3� (1) Square edge with Q W headwall � '9 Q33 20 (Z� Groove end with W � 30 headwall 2 •$ ,$ (3) Groove end �$ 27 projecting 10 .7 �_ 24 8 .7 s To use scale (2) or(3) projeet 21 $ horizontally to scale (1J, then 4 use straight inclined line through I D and Q scales, or reverse as ,6 � 3 illustreted. .6 - 's I 18 ' 2 � 15 l� � I 1�`� � 5 5 5 1.0 ��r�„� f 2 2009 Surface Water Design Manual li9l2009 4-45 SECTION,4.2 PIPES,OUI�FALLS,AND PLA�iPS FIGIJRE 4.2.1.F NOMOGRAPH FOR SIZI'�i TG CIRCULAR DRAINS FLOWING FULL { 1,000 900 800 .0001 700 2.0 600 .0002 500 Minimum .0003 400 .0004 .0001 Allowable .0005 Velocity 300 .0006 (Flowing 3.0 .0008 .0002 Full) �20 n�i .001 108 � .0003 0 200 �� � .002 .0005 4.0 78 � .0006 72 O .003 .0008 66 .004 .001 a .005 5.0 100 60 O .006 ❑ 90 54 cJn .008 .002 o O 80 48 -01 0 / W 6.0 70 w .003 � � 60 U 42 .004�� W 7.0 .02 .005 O 36 � v 50 z 33 .03 •006 w �- g.0 .008 � w z 40 w 30 .04 .�10 � � w a. 27 :Q5 cn Z 9.0 ( � 30 � 24 .08 .020 10.0 � = O 21 .10 � � � .030 � 0 2p � 18 .040 W � .050 � Q 15 .060 p .080 12 .100 10 10 9 SAMPLE USE 8 7 $ 24"dia.CMP @ 2%slope yields 20.0 g 17cfs @ 5.4 fps velocity 5 6 (n=0.024) 4 Values per Manning's equation Q=( 1.49 � ARZ/s g �/z 3 � � 30.0 This table can be converted to other"n"values by applying 2 formula: 40.0 Q1 n2 Q2 n1 1 ( 1 1;912009 2009 Surface�'ater Design I�4anual 4-22 � s � � � � � � � � �e � C.2.2 FULL INFII.TRATIOl� FIGURE C.2.2.A TYPICAL TRENCH INFILTRATION SI'STEM , �' ; i —roof � f drain � RLAN VIEW , N,i,$ —4"rigid or 6 flexble � perforated pipe ! .�------------------�.�_..�_..�..._.____ �� i �' ���.,� ,�_�j ' infiltration trench `sump wlsolid lid I ' -roof drain� ' RLAN VIEW � ' NTS I I � overf�ow -� ; �4"rigid or 6�flexible gpl2�h bloCk��J � � perforated pipe � � f r���r f �` /`�ij. ���f�f !i:�i,fr;<i�� � i`,�li�~i�r�����tii���r.i.���i��`i? ..-.,...:. 6� � 6n ' . . ',L�ry�.""'_'%I'_""'""""'y..""""'""""" � ��� �; wastaed rock -� �=� '-� "�� � �"�,'� 5.0'mi� 12" n�'r�',_ � 1 1/2"-314e '-- - r- - f 1 � 4 i'min . _ -------- -------------------------=--�-----��= � fine rr�esh _ CB sump v.�iaa�i�i i�i crroon � —4'd"��5 —� A -�ir::�=a���� �;* '` .if,'.:. compacEec �ackflil 6" � ,, �;° � ;r 4 _ _. 4.�dg��d or 6" flexib�� :: o '� �s�>L �` perforated �.iF�e 24" `' '' " ��' � c o�t.: �v� c 0 12" � .�� �;? G'✓V- --- Washed rr�r.: \ %� c-6 �;�� r< _ : � � � � w r. � . �r o . _. ��\i.`Li���ti.��r�-- - .. ��!i��;.'��uti�i.` �—24' -a SECTION A NTS 2009 Surface V✓a[er Design Manual-Appendix C 1/9l2009 C-45 ' � C.2.11 PERFORATED PIPE CONNECTIO�T � ❑ TEXT OF INSTRUCTIONS Your property contains a stormwater management f!ow control BMP{best management practice} called a "perforated pipe connection,"which was installed to reduce the stormwater runoff impacts of some or all of the impervious surface on your property. A perforated pipe connection is a length of drainage conveyance pioe with hales in the bottom, designed to"leak" runoff,conveyed bythe pipe, into a gravel filled trench where it can be soaked into the surrounding soil. The connection is intended to provide opportunity for infiltration of any runoff that is being conveyed from an impervious surface(usually a roof} to a local drainage system such as a ditch or roadway pipe system. The size and composition of the perforated pipe connection as depicted by the flow control BMP site plan and design details must be maintained and may not be changed without written approval either from the King County Water and Land Resources Division or through a future development permit from King County. The soil overtop of the perfcrated portion of the system must not be compacted or covered with impervious materials. FIGURE C.2.11.A PERFORATED PIl'E CO�INECTION FOR A SLYGLE FAMILY RESIDENCE random fill /\/\j��j,\j\/��% 6" ���/���/���/��'/���/�%�� (ilter fabric � ���/�����/i��i�/q � p o �o „ � 6'perf pipe 18"min °,��°o � �'a o a� � v � 1 Vz"-3/a'washed rock a oa p4ea oa aa� n o p o �-�,o 0 0 0 pG°oa o ° �-�4 p °oo 0 oo�Qo on4 aov 0 o C o p o � o n � �24" min� TRENCH X-SECTION NTS slope --► to road drainage system 2' X 10' /level trench w/perf pipe PLAN VIEW 4F ROOF NTS 2009 Surface Water Design i�fanual Appendix C 1P9/2009 C-81 PER�, PIPE C�NNECTI�N BMP DETAI� -� C - MAINTENANCE :� r_� � , AYYE�iDIX A �1AINTE�IAi�CE REQUIRE�fEtiTS FOR FLOW'CON"IROL,CONVEY.4NCE,AND Vl-'Q FACILITIES NO. 5-CATCH BASINS AND MANHOLES `:;':':� Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Structure Sediment Sediment exceeds 60%of the depth from the Sump of catch basin contains no bottom of the catch basin to the invert of the sediment. lowest pipe into or out of the catch basin or is within 6 inches of the invert of the lowest pipe into or out of the catch basin. Trash and debris Trash or debris of more than%z cubic foot which No Trash or debris blocking or is located immediately in front of the catch basin potentially blocking entrance to opening or is blocking capaaty of the catch basin catch basin. by more ihan 10%. Trash or debris in the catch basin that exceeds No trash or debris in the catch basin. '/,the depth from the bottom of basin to invert the lowest pipe into or out of the basin. Dead animals or vegetation that could generate No dead animals or�egetation odors that could cause complaints or dangerous present within catch basin. gases(e.g.,methane). Deposits of garbage exceeding 1 cubic foot in No condition present which wouid volume. attract or support the breeding of insects or rodents. Damage to frame Corner of frame extends more than'/.inch past Frame is even with curb. and/or top slab curb face into the street(If applicabie). Top slab has holes larger than 2 square inches or Top slab is free of holes and cracks. cxacks wider than%.inch. Frame not sitting flush on top slab,i.e., Frame is sitting flush on top stab. separation of more than'/.inch of the frame from the top slab. •;`=: Cracks in walls or Cracks wider than%z inch and longer than 3 feet, Catch basin is sealed and ':`� bottom any evidence of soil particles entering catch structurally sound. basin through cracks,or maintenance person judges that catch basin is unsound. Cracks wider than Y:inch and longer than 1 foot No cracks more than'l.inch wide at at the joint of any inleUoutlet pipe or any evidence the joint of inleUoutlet pipe. of soil partides entering catch basin through cracks. � SettlemenU Catch basin has settled more than 1 inch or has Basin replaced or repaired to design misalignment rotated more than 2 inches out of alignment. standards. Damaged pipe joints Cracks wider than%rinch at the joint of the No cracks more than Y.-inch wide at inleUoutlet pipes or any evidence of soil entering the joint of inleUoutlet pipes. the catch basin at the joint of the inleUoutlet ' pipes. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of II pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if ' appropriate. No contaminants present other than a surface oil film. In1eU0utlet Pipe Sediment Sediment filling 20%or more of the pipe. InleUoutlet pipes clear of sediment. accumulation Trash and debris Trash and debris accumulated in inleUoutlet No trash or debris in pipes. ipipes(indudes floatables and non-floatables). Damaged Cracks wider than Yrinch at the joint of the No cracks more than%-inch wide at inleUoutlet pipes or any evidence of soil entering the joint of the inleUoutlet pipe. at the joints of the inleUoutlet pipes. � _� 2009 Surface Water Design Manual—Appendix A 1/9/2009 A-9 APPEI��IX A titAINTENANCE REQUIREMENTS FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES � NO. 5-CATCH BASINS AND MANHOLES Maintenance Defect or Problem Condition When Maintenance is Needed Results Ezpected When Component Maintenance is Performed Metal Grates Unsafe grate opening Grate with opening wider than'/B inch. Grate opening meets design (Catch Basins) standards. Trash and debris Trash and debris that is blocking more than 20% Grate free of trash and debris. of grate surface. footnote to guidelines for disposal Damaged or missing Grate missing or broken member(s)of the grate. Grate is in place and meets design Any open structure requires urgent standards. maintenance. Manhole Cover/Lid Coverllid not in place Coverllid is missing or only partially in place. Cover/lid protects opening to Any open structure requires urgent structure. maintenance. Locking mechanism Mechanism cannot be opened by one Mechanism opens with proper tools. Not Working maintenance person with proper tools.Bolts cannot be seated. Self-locking cover/lid does not work. Cover/lid difficult to One maintenance person cannot remove CoverAid can be removed and Remove cover/lid after applying 80 Ibs.of lift. reinstalled by one maintenance person. s� i � � ��j ,�i����7.,ir����_ , ,� i�, . `,l���n°:_ 1��� ��. � . APPENDIX A 1�tAINTENANCE REQL''IREMENTS FOR FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES -� NO. 6-CONVEYANCE PIPES AND DITCHES Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Pipes Sediment 8 debris Accumulated sediment or debris that exceeds Water flows freely through pipes. accumulation 20%of the diameter of the pipe. Vegetationlroots VegetatioNroots that reduce free movement of Water flows freely through pipes. water through pipes. Contaminants and Any evidence of contaminants or pollution such Materiais removed and disposed of pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective Protective coating is damaged;rust or corrosion Pipe repaired or replaced. coating or corrosion is weakening the structural integrity of any part of pipe. Damaged Any dent that decreases the aoss section area of Pipe repaired or replaced. pipe by more than 20°k or is determined to have weakened structural integrity of the pipe. Ditches Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 Trash and debris Geared from square feet of ditch and slopes. ditches. Sediment Accumulated sediment that exceeds 20%of the Ditch cleanedJflushed of all sediment accumulation design depth. and debris so that it matches design. Noxious weeds Any noxious or nuisance vegetation which may Noxious and nuisance vegetation constitute a hazard to County personnel or the removed according to applicable public. regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of � pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source wntrol BMPs implemented if appropriate. No contaminants present other than a surFace oil film. Vegetation Vegetation that reduces free movement of water Water flows freely through ditches. through ditches. I Erosion damage to Any erosion observed on a ditch slope. Slopes are not eroding. slopes �, Rock lining out of One layer or less of rock exists above native soil Replace rocks to design standards. ' place or missing(If area 5 square feet or more,any exposed native Applicable) soil. �� � 2009 Surface Water Design Manual—Appendix A 1/9i2009 �1-I I �� -��'�_�rfl'(C�� RECORDiNG REQUESTED BY AND WHF,N RECnRI�EI� MATL Tn: CITY CLERK'S OFFICE CITY OF RENTON 1055 SOUTH GRADY WAY RENTON, WA 98057 DECLARATION OF COVENANT �' FOR MAINTENANCE AND INSPECTION OF FLOW CONTROL BMPS Cirantor� ! Grantee: City of Renton Legal Description: Additional Legal(s)on: Assessor's T�Parcel ID#: IN CONSIDERATION of the approved City of Renton(check one of the following) ❑ residential building permit, ❑ canmercial building pem�it, 0 ciearing and grading permit, ❑ subdivision permit, or ❑ short subdivision permit for Application File No. LUA/SWP relating to the real property("Property")described above, the Grantor(s),the owner(s) in fee of that Property, hereby '4 9 � � � covenants(covenant)with City or Renton, a political subdivision of the state of Washington,that he/she(they)will observe,consent to, and abide by the conditions and obligations set forth and described in Paragraphs 1 through S below with regard to the Property. Grantor(s)hereby grants(grant), covenants(covenant), and agrees(agree)as follows: l. Grantor(s)or his/her(their)successors in interest and assigns("Owners")shall retain,uphold, and protect the stormwater management devices, features,pathways, limits, and restrictions, known as flow control best management practices('BMPs"),shown on the approved Flow Control BMP Site Plan for the Property attached hereto and incorporated herein as E�ibit A. 2. The Owners shall at their own cost,operate,maintain, and keep in good repair,the Property's BMPs as described in the approved Design and Maintenance Details for each BMP attached hereto and incorporated herein as Exhibit B. 3. City or Renton shall provide at least 30 days written notice to the Owners that entry on the Property is planned for the inspection of the BMPs. After the 30 days, the Owners shall allow the City of >;� Renton to enter for the sole purpose of inspecting the BMPs. In lieu of inspection by the City,the Owners may elect to engage a licensed civil engineer registered in the state of Washington who has I', expertise in drainage to inspect the BMPs and provide a written report describing their condition. If the i engineer option is chosen,the Owners shall provide written notice to the City of Renton within fifteen days of receiving the City`s notice of inspection. Within 30 days of giving this notice,the Owners, or the engineer on behalf of the Owners, shall provide the engineer's report to the City of Renton. If the report is not provided in a timely manner as specified above,the County may inspect the BMPs without further ' notice. 4. If the City determines from its inspection,or from an engineer's report provided in accordance I with Paragraph 3,that maintenance, repair,restoration, and/or mitigation work is required for the BMPs, '� The City shall notify the Owners of the specific maintenance, repair, restoration, and/or mitigation work j (Work)required under RMC 4-6-030. The City shall also set a reasonable deadline for completing the I ;:{� Work or providing an engineer's report that verifies completion of the Work. After the deadline has � passed,the Owners shall allow the City access to re-inspect the BMPs unless an engineer's report has been provided verifying completion of the Work. If the work is not completed properly within the time frame set by the City, the City may initiate an enforcement action. Failure to properly maintain the BMPs is a violation of RMC 4-6-030 and may subject the Owners to enforcement under the RMC 1-3, including fines and penalties. 5. Apart from performing routine landscape maintenance,the Owners aze hereby required to obtain written approval from the City or Renton before performing any alterations or modifications to the BMPs. 6. Any notice or approval required to be given by one party to the other under the provisions of this Declaration of Covenant shall be ef�ective upon personal delivery to the other party, or after three(3) days from the date that the notice or approval is mailed with delivery confirmation to the current address on record with each Party. The parties shall notify each other of any change to their addresses. 7. This Declaration of Covenant is intended to promote the efficient and effective management of � . surface water drainage on the Property, and it shall inure to the benefit of all the citizens of the City of Renton and its successors and assigns. This Declaration of Covenant shall run with the land and be binding upon Grantor(s),and Grantor's(s')successors in interest and assigns. 8. This Declaration of Covenant may be terminated by execution of a written agreement by the , Owners and the City of Renton that is recorded by King County in its real property records. � � IN WITNESS WHEREOF,this Declaration of Covenant for the Maintenance and Inspection of Flow Control BMPs is executed this day of , 20 . GRANTOR, owner of the Property GRANTOR, owner of the Property STATE OF WASHINGTON ) COLJNTY OF KING )ss. On this day personally appeared before me: ,to me known to be the individual(s)described in and who executed the within and foregoing instrument and acknowledged that they signed the same as their free and voluntary act and deed, for the uses and purposes therein stated. Given under my hand and official seal this day of ,20 � Printed name Notary Public in and for the State of Washington, ', residing at My appointment expires `� � ' Section 5: Conveyance System Analysis and Design This analysis and design will be provided as part of the Construction Plan submittal to the City of Renton. t � Section 6: Special Reports and Studies Geotechnical Study attached ��������������� �� � ����������� ��.����_� � � � � ����3�����-►nica►1 �r�gin�ering c�rnd Fs�rtf-� ,��i�r� ��.� ------- — -------- ; � March 26, 2013 ; ; , � ; Mr. Kyle Miller , � ! KRRV Development, LLC ; P. O. Box 908 ' � Ravensdale, WA 98051 ' ; i I � � SUBJECT: GEOTECHNICAL EVALUATION � Proposed Residential Development ; 3517 & 3603 N E 7`h Street , Renton, Washington !, ; Project No. 13-103-01 � ' Dear Kyle, � li, : This repo�t presents the results of our geotechnical evaluation for the site of your II proposed new residential development on the subject properties. The purpose of our work was to provide geotechni�al engineering evaluations of the site and geotechnical recommendations for the residential development including design of foundations, site grading, erosion control and site!drainage. Our work was performed in accordance with � the scope and conditions of our proposal dated ,;anuary 26, 2013. � A site topographic map and 'preliminary development plans (see Figure 2) were ; provided to us and was used as'a reference for our evaluations. Based on our review of � � the plans provided and discussions with you, we understand that the subject two � properties will be divided into eight new lots and the development of the new lots will j include new 2-story or 3-story wood-frame residences supported at grade (no ; basements) on each of the new lots. The structures will include ground level garages ; � with slab-on-grade floors. The ground floors of the residence structures may be raised ; floors with crawl space or may be slab-on-grade. � ; � We assume that bearing wall loads will be in the range of about 2 to 3 klf and maximum � column loads to be in the range of about 10 to 20 kips. !f actual structural loads exceed + the above values by more than 25%, this office should be notified. ; � Review of the Renton online Sensitive Areas Maps indicates that the properry is not � � indicated to be within a Landslide Hazard, Erosion Hazard, Seismic Hazard or Coal ! Mine Hazard area. � ; � !----- P..�. �ox276, Issaquah, WA �8027-027� • Phone: (425)391-,4228 rax (�25} 39?�r;�� � KRR�/ Development, LLC March 26, 2013 SCOPE OF WORK Our geotechnical evaluation included review of geologic mapping, site explorations, engineering analyses and evaluations and the preparation of this report. The scope of work included the following specific tasks: � o Review of published geologic mapping of the site vicinity. o Performed a reconnaissance of the site as well as observations of the adjacent developed lots. o Observed and logged nine test pit explorations within the two properties (see Figure 2) to depths up to 4.5 feet below existing ground. Logs of the test pits and results of field and laboratory testing are presented in the Test Pit summaries of Appendix A. o Performed geotechnical engineering evaluations of the proposed site development and developed our geotechnical recommendations for foundation design, site grading, drainage and observations during construction. o Prepared this geotechnical report summarizing our findings and recommendations. OBSERVED SITE CONDITIONS The property is bordered on the west, south and east by developed residential lots (we have recently performed a geotechnical eva!uation for new development of the adjoining property to the west). At the time of our field exploration the properties were developed with residences and out buildings as shown in Figure 2. The topographic mapping included on the site plan of Figure 2 indicates that the subject � properties generally slope very gently down to the west/southwest at gradients that range from only about 2 to 7 percent in localized areas and the overall average gradient across the site is only about 4 percent with an elevation difference across the site of about 14 feet from northeast to southwest. We noted a small (less than 10 feet) but steep slope adjacent to the south property line in the central area of the site (south of TP-7 location) which appears to be a cut slope created for development of the adjoining property to the south. The site was well vegetated primarily with grasses but also included shrubs, fruit trees � and evergreen trees up to about 3.5 feet in diameter. We did not observe any seeps or springs or evidence of current or past erosion on the site. Project No. 13-103-01 Page 2 KRRV Development, LLC March 26, 2013 Subsoils Our evaluation of the subsurface conditions was based on our observations of nine exploratory test pits within the site plus review of published geologic mapping. Approximate locations of the test pits are shown on Figure 2. Logs of the test pits are presented in Appendix A. Subsoils encountered in our test pits were found to include some minor fill and natural glacially consolidated soils. Fill soils were encountered in TP-1 located at the northwest corner of the site. Fill soils were silty very fine sand with occasional gravel and were only about 1 foot thick at that location. We also noted an oil tank fill cap near the northwest corner of the existing house on the 3517 property which indicates another likely area of fill/backfill. Natural soils encountered at the test pit locations were generally silty fine sand with gravel. The upper soils were typically loose to medium dense soils to depths of about � to 3.5 feet below the natural surface becoming very dense and hard and cemented ai greater depths. Subsoils encountered in TP-7 adjacent to the sma(I but steep slope adjacent to the south property line were also natural soils very similar to soils encountered at the other ` ' � ' ` ' ` '` ' -�r.r�-�rr:r�i!�r ,--r�-��n�� h+i ^. ' Ground VVater No ground water or seepage was observed in any of the test pits. Typicaliy the shallow soils on the 3517 property were classified as moist to very moist and the shallow soils on the 3603 property as well as the deeper cemented soils were cfassified as moist. The measured moisture contents of the soils generally ranged from about 7+ to 16+ percent. Subsurface Variations Based on our experience, it is our opinion that some variation in the continuity and I! depth of subsoil deposits and ground water levels should be anticipated due to natural ' deposition variations and previous onsite structures and grading. Due to seasonal moisture changes, ground water conditions should be expected to change with time. Care should be exercised when interpolating or extrapolating subsurface soils and ground water conditions between or beyond our test pits. Project No. 13-103-01 Page 3 , KRRV Development, LLC March 26, 2013 SITE EVALUATIONS General The referenced geologic map of Figure 1 indicates the site vicinity to have surface exposures of glacial till (Qgt) soils. The Qgt g�acial till soils are highly consolidated, heterogeneous mixtures of sand, silt, clay and gravel soils deposited during the advance of the Vashon glaciation, the last glacial advance into the Puget Sound area, approximately 13,000 to 16,000 years ago. Based on the soils observed on the site and review of the referenced map, it is our opinion that the natural very dense/hard silty sand with gravel soils underlying the site and are most likely glacially consolidated till deposits (Qgt). Based on the results of our field investigations combined with our own experience and judgment, it is our opinion that the geotechnical site conditions are suitable for the proposed development provided our recommendations are followed. Hazard Assessment Landslide: The Renton Sensitive Areas Maps indicate the site is not within a Landslide Hazard area. In addition, the geologic map of Figure 1 indicates no mapped landslides within the site vicinity and our site observations indicate the site is currently stable. Considering the very gentle slope gradients and the observed glacial till soils, it is our opinion that the potential for future instability on the site is very low to nil. The proposed structure locations in the southern lots are 20+ feet from the observed small slope on the adjacent property to the south in our opinion that slope should have no impact on the proposed structures. Erosion: The Renton Sensitive Areas Maps indicate the site is not within a Erosion Hazard area. We observed that the site is well vegetated we observed no indication of any seepage or concentrated water flow or current or past erosion on the site. Based on our site observations and explorations it is our opinion that there is no unusual , erosion risk at this site and any potential erosion potential resulting from development ', will be mitigated by our recommended grading procedures and drainage/erosion control ' measures and by final re-vegetation/landscaping incorporated into the proposed ' development plans. Coal Mine: The Renton Sensitive Areas Maps indicate the site is not within a Coal Mine Hazard area. Seismic: The Renton Sensitive Areas Maps indicate the site is not within a Seismic Hazard area, however the Puget Sound region is a seismically active area. About 17+ moderate to large earthquakes (M5 to M7+) h,�ve occurred in the Puget Sound and northwestern Cascades region since 1872 (141 years) including the 2/28/01 M6.8 Project No. 13-103-01 Page 4 KRRV Development, LLC March 26, 2013 I • � di iso r h s ds wi v li Nisqually earthquake an t u opinion that t e propo e tructures II ery kely experience significant ground shaking during their useful life. ' Based on a recently published study the site lies only about 2.5 miles south of the , southern mapped location of the Seattle fault and about 18 miles southwest of the estimated trace of the South Whidbey-Lake Alice fault both of which have postulated �, maximum credible magnitudes of 7.0 to 7.5. Another recent study of the Vashon- ', Tacoma area presents evidence for the east-west trending Tacoma Fault which is � indicated to pass through the south end of Vashon and the middle of Maury Island about 10.5 miles southwest of the site. The study suggests that the Tacoma Fault and , the Seattle fault may be linked by a master thrust fault at depth. The Seattle fault has been documented to have moved at its west end (Bainbridge Island) about 1000 to 1100 years ago and evidence of movement at the east end has also recently been documented. Some expe�ts feel that the recurrence interval between large events on the Seattle Fault may be on the order of several thousands of years but our calculations indicate it may be on the order of 1200 to 1400 years. The activity of the documented Tacoma fault is considered to be on the same order as the Seattle fault. The recurrence of a maximum credible event on the South Whidbey fault is not known but some experts have assigned a recurrence of about 3000 years, however smaller events will occu� more frequently as evidenced by the 5.3 event on May 2, 1996 which was attributed to that fault. In addition to Puget Sound seismic sources, a great ea�thquake event (M8 to M9+) has been postulated for the Cascadia Subduction Zone (CSZ) along the northwest Pacific coast of Oregon, Washington and Canada. The current risk of a future CSZ event is not known at this time. Published reports have indicated recurrence intervals for a CSZ event to range from as little as 100-200 years to as long as 1000+ years and the time of the last event is reported to have been about 313 years ago. The 2009 International Building Code (IBC) adopted by the City of Renton requires consideration of a spectral acceleration level with probability of exceedance of 2 percent in 50 years for seismic structural design. This corresponds to about a 2475- year recurrence interval earthquake ground motion. Based on the short period spectral response accelerations presented in Figure 1613.5(1) of the 2009 IBC, adjusfed as per equations 16-36, 16-38 and factored as per section 1803.5.12(2), we estimate the IBC peak ground acceleration for soils and foundaticn design at this site to be about 0.38g. Please note that the 0.38g peak ground acceleration includes the additional reduction factor of section 1803.5.12(2) and is not intended for structural analyses. We recommend the site be considered a Site Class D for structural design. Secondary seismic hazards due to earthquake ground shaking include induced slope failure, liquefaction, lateral spreading and ground settlement. Considering the very dense/hard nature of the soils recommended for bearing at the site, it is our evaluation that the potential for damage to the structures due to liquefaction, fateral spreading and settlement is very low to nil. The potential for seismically induced shallow failures on Project No. 13-103-01 Page 5 ,KRRV,Development, LLC March 26, 2013 the site is also considered very low to nii and the potential for shaltow failures within the smali adjacent cut slope to the south is also considered very low. Structure Support Considerations In our opinion the undisturbed very dense/hard natural glacial till soils encountered in our explorations should provide good support for the proposed structure foundations. Bearing soils are expected to be encountered at depths ranging from about 2 to 3.5 feet below the natural ground surface at the site. Foundations should penetrate through any existing fill, topsoil and loose/medium dense soils to bear on undisturbed very dense/hard natural soils. Conventional spread footings are considered appropriate for support of the proposed structures considering that bearing soils are at shallow depths. However, if any deep fill areas are encountered on the site (such as backfill of tank or structure removal excavations), lean concrete footing extensions or pipe piles cou�d be used to transfer foundation loads to the deep bearing soils in those areas. We have include�l recommendations for spread footings and pipe piles in this report. RECOMMENDATIONS , The following subsections present our recommendations for design of foundations, site grading, drainage control and erosion control. Also included are recommendations for plan review and observations and testing during construction. � Spread Footinq Foundations � Conventional spread footings founded on undisturbed very dense/hard natural glacial till soils should provide good support for the proposed structures. Bearing soils are expected to be encountered at depths ranging from about 2 to 3.5 feet below the � natural ground surface of the site. Continuous wall footings should be at least 18 inches wide. Square footings for column ; support should be at least 24 inches wide. Footings supported on undisturbed very dense/hard natura! glacial till soils may be designed based on an allowable bearing pressure of 2000 psf. ' All footings should be founded at least 18 inches below the lowest adjacent final grade. I Where the natural bearing soils slope, the footing excavation should be stepped to , maintain a horizontal bearing surface. '� If deep fill or other unsuitable soils are encountered, foundation loads may be transferred from the recommended minimum foundation depths to the recommended ; Project No. 13-103-01 Page 6 KRRV Development, LLC March 26, 2013 very dense/hard bearing soils by a monolith of lean concrete having a minimum compressive strength of 1000 psi. The width of an un-reinforced lean concrete monolith should be at least as wide as the footing or at least one-third of the monolith height, whichever is greater. Reinforced monoliths should be designed by a structural engineer. A suitable width trench should be excavated with a smooth edged excavator bucket (no teeth) to expose the dense/very dense bearing soils under observation by our office and backfilled as soon as possible with the lean concrete to the footing elevation. The estimated settlement of a 18-inch wide continuous footing carrying a load of 3 kips per foot is on the order of 1/4 to 1/2 inch. Our settfement estimates assume that foundations are supported on undisturbed very dense/hard natural bearing soils and that all fill and loose/disturbed material is removed from the bearing surface prior to concrete pour. Maximum differential settlement within the proposed structures is expected to be 112 inch or less. Settlements are expected to occur primarily during construction. Resistance to lateral loads can be assumed to be provided by friction acting at the base � of foundatior.s and by passive earth pressure. A coefficient of friction of 0.45 may be assumed with the dead load forces in contact with on-site soils. An allowabte static passive earth pressure of 250 psf per foot of depth may be used for the sides of footings poured against undisturbed medium dense natural soils or properly compacted structural fill. An allowable static passive earth pressure of 150 psf per foot of depth may be used for the sides of footings or grade beams poured against existing loose soils. The ve�tical and lateral bearing values indicated above are for the total dead load plus frequently applied live loads. For short duration dynamic loading caused by seismic or wind forces, the vertical bearing values may be increased by 50 percent and allowable lateral passive pressures may be increased by 33 percent. Driven Pipe Pile Foundations If deep fill or other unsuitable soils are encountered, foundation loads may also be transferred from the recommended minimum foundation depths to the recommended very dense/hard bearing soils by properly constructed pipe piles. This type of support is constructed by driving 2-inch or 3-inch diameter steel pipe to refusal into the bearing soils below existing unsuitable soils. Based on our experience, piles typically penetrate about 5 to 15 feet into the bearing soils before encountering refusal. Refusal penetration rates for pifes will depend on the hammer size and the load testing results. Refusal penetration rate for a 3-inch pile driven with a tractor-mounted 6501b hydraulic hammer typically should be in the range of about 15 to 20 seconds per inch. Refusal penetration rate for a 2-inch pile driven with a tractor-mounted 6501b hydraulic hammer typically should be in the ranQe of about 8 to 10 seconds per inch KRRV Development, LLC March 26, 2013 Alternatively 2-inch piles may be driven using a 901b jack hammer plus the weight of the operator or using a 140+Ib rinho-type pile-top pneumatic hammer to a refusal penetration rate of 1 inch or less per minute. We recommend that all pile installation be observed by our office to verify the allowable capacity and refusal criteria for the production piles. An allowable verticaf downward capacity of 6 kips (Factor of Safety = 2+) may be assumed for 2-inch diameter piles and capacities of 10 kips (Factor of Safety = 2+) can generally be assumed for 3-inch diameter piles installed as recommended above. No uplift capacity or lateral support should be assumed for driven pipe piles. No lateral support should be assumed for the pier shafts. Resistance to lateral loads can be provided by battered piles (compression only) and by passive earth pressure against the sides of grade beams. An allowable static passive earth pressure of 150 psf per foot of depth may be used for the sides of grade beams poured against existing loose soils. Capacity may be limited by the structural capacity of the pipe and connections which should be determined by the structural engineer. The pipe and couplers which form the pile, must be of structural quality (schedule 40+) and must be provided with a corrosion resistant coating (galvanized). The pipe pile suppo�ts should be capped with a grade beam to transfer structural loads to the piles. The pile/grade beam system should be designed by a qualified structural engineer. Site Gradinq Site grading is expected to consist primarily of excavation for proposed foundations and subgrade preparation for slab and pavement areas and utility trenches. Onsite granular soils cleaned of debris and organics are considered suitable for use in general compacted fills but in our experience the onsite glacial til! soils will be moisture sensitive with regard to grading and compaction characteristics. Grading should be scheduled for the late summer months if possible. Wet weather grading may require the use of imported clean granular fill soils which are more easily compacted at higher moisture levels. Recommendations for site preparation, temporary excavations, structural fill, subgrade preparation, site drainage and trench backfill are presented below. Site Preparation: Existing vegetation, debris, fill soils, and loose or organic natural soils should be stripped from the areas that are to be graded. During rough grading, excess soils may be stockpiled for later use. Stripping in subgrade areas is expected to average about 1 foot. Soils containing more than 1% by weight of organics may be used in planter areas, but should not be used for structural fill. Stumps, debris and trash, plus rocks and rubb(e over 6 inches in size, should be removed from the site. Subsoil conditions on the site may vary from those encountered in our test pits. Therefore. our office shoufd observe the prepared areas prior to placement of any ne�v t��;'�. KRR�/ Development, LLC March 26, 2013 Temporary Excavations: Sloped temporary construction excavations may be used where planned excavation limits will not undermine existing structures or interfere with other construction. Where there is not enough room for sloped excavations, shoring should be provided. Based on the subsurface conditions encounter�d in the test pits, it is our opinian that sloped temporary excavations may be made vertically to depths of 4 feet or less. ' Excavations up to 10 feet in depth should be sloped no steeper than 1:1 within loose/medium dense soils and no steeper than %z:1 (horizontal:vertical) within the un- weathered, hard cemented natural glacial till soils. It should be noted that the contractor is responsible for safety and maintenance of construction slopes. We recommend that cuts over 4 feet in depth be covered with visqueen tarp to help control ravelling and sloughing. Surface drainage should be directed away from the top edge of cut slopes. Surcharge loads should not be allowed within 5 feet of the top of the slope or within a 1:1 (horizontal:vertical) plane extending up from the toe of excavation, whichever is �reater. � Structural Fill: Provided that soil moisture can be reduced and maintained near optimum, excavated onsite soils cleaned of organics and debris may be used for general structural fill but the onsite soils are expected to be moisture sensitive and during the rainy season the soils may become too wet for practical compaction. Therefore impo�ted granular fill soils should be used if moisture conditions cannot be adequately controlled. Loose soils, formwork and debris should be removed prior to placing fill or backfill. Structural fill should be pfaced in horizontal lifts not exceeding 8 inches in loose thickness and compacted to at least 90 percent of the maximum dry density as determined by the ASTM D1557 test method. Imported granular fill should consist of clean, well-graded sand and gravel materials free of organic debris and other deleterious material. Imported material for wet weather grading should be a sand/gravel mixture with less than 5 percent fines based on the sand fraction. SIab/Pavement Support: Slabs-on-grade and pavement should be supported directly on undisturbed dense natural soils or on properly compacted structural fill over medium dense natural soils. Where unsuitable soils (existing fill, loose and organic soils) exist at subgrade levef, subgrade preparation should include excavation of the unsuitable soils as required to expose medium dense natural soils or to a maximum depth of 2 feet (or deeper as required to remove all organic soils where organic soil depths exceed 2 feet beiow final subgrade) and placement of structural fill to final subgrade elevation. Subgrade fill should be placed in accordance with the recommendations for structural fill except that the top 6 inches of the subgrade fill should be compacted to at least 95 percent of the ASTM D1557 maximum dry density in pavement and driveway areas. Project No. 13-103-01 Page 9 . KRRV Development, LLC March 26, 2013 It should be noted that where the proposed slabs crass a fill/natural contact line, there will be a high risk of cracking. Risk of cracking can be reduced by placing construction joints at the contact and by proper steel reinforcement of the slab. Interior concrete slabs should be underlain 6y a capillary break consisting of a polyethylene vapor barrier of at least 6 mil thickness. Utility Trenches: Buried utility conduits should be bedded and backfilled around the conduit in accordance with the project specifications. Bedding material should extend from six inches below the pipe to six inches above the pipe. Where conduit underlies pavement or slabs-on-grade, the remaining backfill above the pipe should be placed and compacted in accordance with the recommendations for structural fill. If imported granular fill is used for trench backfill it should be capped with 12 inches of onsite silty soils. Draina�e Control Surface drainage from the site and adjoining upslope areas should be controlled and ! dive�ted around the development area in a non-erosive manner. Adequate positive drainage should be provided away from the structures and on the site in general to prevent water from ponding and to reduce percolation of water into subsoils. Granular backfill should be capped with paving or 6 inches of onsite silty soils. A desirable slope for surface drainage is 2% in landscaped areas and 1% in paved areas. Roof drains should be tightlined into the storm drain system (no discharge on the ground surface). A permanent perimeter drain, independent of the roof drain system, should be placed adjacent to the base of the continuous exterior foundations. The drain should consist of a four-inch diameter perforated PVC drain pipe placed in at least one cubic foot of washed drain gravel per lineal foot along the base of the foundations. The drain gravel zone around the pipe should be encapsulated with a membrane of Mirafi 140 filter fabric or equivalent between the drainage zone and onsite silty soils. Erosion Control Although we observed no evidence of erosion, onsite soils are expected to be erodible when distur�ed and exposed to concentrated water flows. Siltation fences or other detention devices should be provided around the downslope side of the disturbed site area and soil stockpile areas during construction to controi the transport of eroded material. The lower edge of the silt fence fabric should have "J" shaped embedment in a trench extending at least 12 inches below the ground surface. Surface water flow should be collected in area drains and tightlined to the storm water system, no water should be discharged on the site unless via a properly designed and approved infiltration/dispersion system. ExposPd final graded soil areas should be planted immediately with grass and deep rooted plants. Project No. 13-103-01 Page 10 KRRV Development, LLC March 26, 2013 Plan Review This report has been prepared to aid in the evaluation of this site and to assist the architect, structural and civil engineers in the design and construction of the project. It is recommended that this office be provided the opportunity to review the final design drawings and specifications to determine if the recommendations of this report have been properly implemented and to make any suppfemental design recommendations which may be required. Observations and Testinq Durinq Construction Recommendations presented in this report are based on the assumption that soil conditions exposed during construction will be observed by our office so that any necessary design changes or supplements may be made. Foundation excavations should be observed to verify that they expose undisturbed very dense/hard bearing soils and that excavations are free of loose and disturbed materials. ' All pile installation and testing should be observed by our office to confirm the allowable I'i design capacities. Refusal criteria for all driven pipe piles should be confirmed by our office. Surface and subsurface drainage provisions should be verified by our office. �I All structural fill and slab/pavement subgrade areas should be observed by a representative of this office after stripping and prior to placing fill. Drainage control systems should be observed by our office to verify proper construction. Proper fill placement and compaction shoutd be verified with field and laboratory density testing by a qualified testing laboratory. Project No. 13-103-01 Page 11 ,KRR� Development, LLC March 26, 2013 CLOSURE j This report was prepared for specific application to the subject site and for the exclusive �, use of KRRV Development, LLC and their representatives. The findings and conclusions of this report were prepared with the skill and care ordinarily exercised by ', local members of the geotechnical profession practicing under similar conditions in the same locality. We make no other warranty, either express or implied. Variations may exist in site conditions between those described in this report and actual conditions encountered during construction. Unanticipated subsurface conditions commonfy occur and cannot be prevented by merely making explorations and performing reconnaissance. Such unexpected conditions frequently require additional expenditures to achieve a properly constructed project. If conditions encountered during construction appear to be different from those indicated in this report, our office shauld be notified. Respectfully submitted, GEOSPECTRUM CONSULTANTS, INC. ,��� � � . ra �,��l� � � h�� F';L'n.5',:' ; • ...�' � (:l• �f? _ � �:'�, �`, James A. Doolittl "' �`T �'�" r:�` - Principal Engineer - '_ � 2;(k ,� �f;`;�; 2�•;�3 ' �Q �FGI�;�?t%�`� ,' Encl: Figures 1 and 2 �s --- .�;N `Sr�:j�,f,�'Y�l Appendix A '��,, �iPlRcS ?�t� �% Dist: 2/Addressee Project No. 13-103-01 Page 12 i •.�.�_I..F•'�•It�q�� %f� �1( �./E��l �7 �: i t� � . . \ ��_ �, � �� l� � ---- ' �l 1 I�1�1� `�� `\ ;I';��ti,�r—JI��. I1 �! '! �r Ii . ' l -t R , ..4 � .,�! i ��i�F.. �- r „ �� g-� ,;:. .� � r. .• ,. ' ` i��o1� 1�� �ri . 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' � [�} a � � �� ,�__�-_-- �- _ � \ , �C� i � .�1�.-.1r— - -- c�� � ��i �n��fj� �. -. � ; ,- � , �� �� Ta�,K Te'at�ng V +sti , �;�, '�,� �:�- � �� X }; .: � A��� �, � � 4cE , _ „��E ; ^, '� 4� ;;�i3 li (A��nac�.neti) ii '� , - i '� ; '�� �; , ' ��=�-`_-__--=�`-�' �`�- : � ,�j _ r�,��;.����.. �,_ �: �f�,� C a , ,T;, ; �j'� tl � � � ' �° �. , , - '; ! t \ v.' f . "i ! , . �' r �,,� ' ,t .. i /�i i �fVl. �".� i �� i�C_,,,_i„s��7��� �._ 1`�+ . S'�i � .. � " ' � `� �'Y t� � / �� J�__ J�. . . � . � � t � r j: ,' � �✓'�<--�;�. �; r �-� ':;,;� '� �• ` �1 �� �j � � �'--r" � � � �y/ � / � }':J1 f;..� � ' ` � . .. . �� � il 7 C�,t` i �l__ '\ �/ ���' � '`���� S//�� , I �`` . _ - t...��1 . . `. %'" �-`�'� � / � � / � .\ ! . ���J�{ '���. � ;���/�.��,��.J `�! t����i{.�,�-�1 _��\� i . � � . �.-1` � ` ____�-�i _ _ ..—� \� t '"'�� } � .. . .. . . � � t�� i�� � . ' `tt�� '� �� ���� `��/'� } � �.. { .\ ,4 ��.: ��-�� - af �_� , � . �, �-,' a� �i . \� .1� � ..�. .y�.����r�t�� s aae����� � 'G' .� �i'�{ i,�� __ _ :I• ��i . �`�--_'_---_ _. /'-1��C—a.:.._��-� .•_ y�'�.:_+�v.�_ ..-:—i-1... . �..-�1:' . . /�9 ref: Geoloc�ic Map of the Renton Quadrangle by D. R. Niullinea�ux, USGS Map GQ-405, 1965 _ SITE VICINITY GEOLOGIC MAP GEOSPECTRUM CONSULTANTS, INC.. 3517�&�3603s��e7�aStreetlopment � ,��, > Renton, Washington r>;: � Gaotochn/co!Eng/noo�/ng ond Eorfh Scloncos Proj. No. 13-10 Date 3/13 Figure 1 � � � ,' ;`NE 7TN STREET' ' � ; r � � � � - ' I � � �a-s i — — — — '— Z— — —�—i t — — --�- � � .. ,\ � , � : • '�__.�. ' ^�^^�'�. . i � � � ..,.�.e......,...,...�..�M..,.� --' �. _ ,�� — � —__ ' .'.' 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' . _. s� �\% '3 �:1'v/ %�/ ������/� ;�� � M N ° � 1 ' . � _ � N _ � i i�.__�'4'"iii.1�j l t '�y � /`'7/� > �' 'i \ �' `��" . __� _ � " I ��\ '`�.. r�'I li%{ ` �� � � ��-- � ��//i�i,/.,:-.t � ,.� \ � \�c.r^ �;.� _ 11`:.::y!!:cl1' � : - ..'—��7 �_.�Y ! s � '�'1�n: �� C��,'� � . ,. ,. , . _ . 1 .f :�`� �r l., •� >�. ' - �I ��-- �w � o ,� �.. _ ....... _ -- - " - ' �` �� � �,\���� _ �� -- - --- �. � > � � ., l __ `�=.�x��" TP—4 �;- .o` 5� . . ...�i � �i � � . �' �� , . ... .. . �.�i `� n ^ .!v�. _ �' �, b--- � �— , _ ;� � _. ,, ` ;.�. '. `....... .,.... ..- ; - � O � ✓l�,��: 35 ! _f tl� � � ;�� %' _ � . f�� U ?�1-� td ,f�, `.' �, �;p-9 �� .n � � ,�„�j `.. =�; �� R.b � `� �' �; - rd a� sz �_= ; " :;�'�� �� " � � , � o �i , . �� t. i� `� _ � �� � TP�2���..:'�%� : , `: �0 � c� � : :i �� � � . - , �. . --a.- �` . _: . :� :;� :i ���� �.. _. _ _ .. . . . ... , ` w �, _ __--,„� ��-... �:c � ; � : . . . � ,, �i �,� < , ,� `��-�' ,y ,., . Tp'-� N � � b ' � �: � � ,, . �;.... . . ��.. _ � . ._. . % �o' `ti�o� ,;'� ,�„ ! � . � ;�— �i �n: �o: a - � '`�. � '�' � ` ^'Y, i_ ,�c\ y'` _., r�-�} i ; } , � � , � + ._ . , 1. .\\�,�--=�� . . ...... _ .. . _ . . . _ . .TP-8� � :'1^ i � �'4� '� \, ,'. C ��r__ 1 '.�� TP-7� ��3,�- �;Y��. } � ---,�`�_ '� �: ;;;.� __�:, — � . - . — - �..,, �y� � SITE DEVELOPMENT & EXPLORATION PLAN GEOSPECTRUM CONSULTANTS, /NC. �oposed Residential Development 3517 & 3603 NE 7th Street ;�;: Renton, Washington Gaofochn/co/Englnoor/ng ond 6o��h �c,on�.�s Proj. No. 13-103 Date 3/13 Figure 2 f , APPENDIX A FIELD EXPLORATION Our field exploration included a site reconnaissance and test pit explorations. During the site reconnaissance, the surface site conditions were noted, and the locations of the test pits were approximately determined. The test pits were approximately located using the existing structures as a guide. The approximate locations of the test pits are shown on Figure 2. Test Pit elevations were estimated based on the topographic mapping shown on Figure 2. Test pits were advanced using a trackhoe excavator. Soils were continuously logged and classified in the field by visual examinaticn, in accordance with the ASTM Soil Classification system. Logs of the test pits are presented on the test pit summary sheets A-1 through A-5. The test pit summaries include descriptions of the soils and pertinent field data. Soil consistency and moisture conditions indicated on the logs are interpretations based on the conditions observed in the field. Boundaries between soil strata indicated on the logs are approximate and actual transitions between strata may be gradual. , • TEST PIT NO. 1 Logged by JAD Date: 1I31/13 Elevation: 406' Depth Blows Class. Soil Description Consistency Moisture Color W(%) Comments � SM Silty fine Sand w/occ grave! loose moist dk brn FILL � � ---...... 1 ..brown --� - --�--- - � ................... ............. ....... .... .- .......... ........ . - SM Siity fine Sand w/occ gravel medium brown dense to 2 .... .............. ....-- ---.. dense moist/ �ed- 16.5 ve rown i m o�st 3 ...... - -- - -- - _ __ __ - - - I very moist gray , w/some cementation da��se/ 9 6 � 4 '� 5 Maximum depth 4 feet. , 6 No ground water encountered. 7 TEST PIT NO. 2 Logged by JAD Date: 1/31/13 Elevation: 403' Depth Blows Class. Soil Description Consistency Moisture Color W(%) Comments � SM Silty fine Sand w/arganics loose moist �ark ......... ......................................�-� --- �-- to rown 1 SM Silty fine.�Sand brown wi h occ. gravel to 6" very 13.4 moist 2 ...m:d�nse.. 3 �cemented- . .. .- - - . . v: �errsel. .-m�isC��-�-- 4 5 Maximum depth 3.5 ft. 6 No ground water encountered. 7 GEOSPECTRUM CONSULTANTS, INC. Proposed Residential Development � �- _�` ; �` 3517 & 3603 NE 7th Street ,. �.�-. _ Geotechnrcal En ineerin and Earth Sciences Renton, WBShi� totl Proj. No. 13-103 Date 3/13 Figure A-1 � ' TEST PIT NO. 3 Logged by JAD Date: 1/31/13 Elevation: 400' Depth Blows Class. Soil Description Consistency Moisture Color W(°/a) Comments � SM Silty fine Sand w/occ gravel ioose moist dk brn ..... - & abundant roots to 4" to brown 1 very 15.8 moist 2 .... - - --.. - ....._... �ens�em ��o�n 3 . -� .............. ..�- - .. .... - ._........ .........._........ ................ very moist gray w/some cementation da��se/ 9 6 4 5 Maximum depth 4 feet. 6 No ground water encountered. 7 TEST PIT NO. 4 Logged by JAD Date: 1/31/13 Elevation: 405.5' Depth Blows Class. Soil Description Consistency Moisture Color W(%) Comments � Sod/or anics loose moist dark,brn ......... ..... .�--..9-...�..... �- �-- .................... 1 SM Silty fine Sand t� brown with gravel to 3" very moist 2 ................... ............... �ens�em b�own 10.5 3 _cemented� .. . _ _.. V:�d��nsel.. . moist. . . g�ay . 8.4 4 5 Maximum depth 4 ft. 6 No ground water encountered. 7 GEOSPECTRUM CONSULTAIVTS, 1NC. Proposed Residential Development � .: i �; ' = 3517 & 3603 NE 7th Street . _ ;.-._�� Geotechnical En ineerin and Earth Sciences Renton, Washington Proj. No. 13-103 Date 3/13 Figure A-2 . � T�s-r Pir No. � Logged by JAD Date: 1/31/13 Elevation: 411' Depth Blows Class. Soil Description Consistency Moisture Color W(%) Comments � loose moist dk brn Sod/organics ......... ....... . ............_....._............... ................ SM Silty fine Sand wlocc gravel to br�wn � & abundant roots t� very dark b ro�vn 2 r�ediem moist 12.1 3 ......._._... - - -..... ............. - - � --- cemented hard moist ra 10.6 4 5 Maxirnum depth 3.5 feet. 6 No ground water encountered. 7 TEST PIT N�. 6 Logged by JAD Date: 1l31/13 Elevation: 404' Depth Blows Class. Soil Description Consistency Moisture Color W(%) Comments � gM� Gravell Sil Sand loose moist dark GM.. ............�vith�ravel__to 3" __brown .......... to - .. 1 SM Silty fine.�Sand brown wi h occ roots r�edium . .............._..._ ._ ....ense-- ... . ..._...... . . ................ 2 r�edium �ra�- 10.3 ense ro n 3 cemented�-... ...............- ...hard� --.._. ..�r�y._... 9.8 4 5 Maximum depth 3.5 ft. 6 No ground water encountered. 7 GEOSPECTRUM CONSULTANTS, INC. Proposed Residential Development _ ri,�x �£i s� -; 3517 & 36Q3 NE 7ih Street I Geotechnicaf En ineerin and Earth Sciences Renton, Washin tOn , Proj. No. 13-103 Date 3/13 Figure A-3 , . � TEST PIT NO. 7 Logged by JAD Date: 1/31/13 Elevation: 403' Depth Blows Class. Soil Description Consistency Moisture Color W(%) Comments � Sod/or anics loose moist dk brn ..... . . ............9... - ........------....--��-- ........_ ...._........... SM Silty fine Sand wlgravel ed- 1 �rown & occ gravel to 6" 10.2 --� ......... li�ht 2 �- .... ..--�- b own �edium ense 3 ....................................... ......... .. ... ............... cemented v.dense/ gray 7.4 hard 4 5 Maximum depth 4 feet. 6 No ground water encountered. 7 TEST PIT NO. 8 Logged by JAD Date: 1/31/13 Elevation: 406' Depth Blows Class. Soil Description Consistency Moisture Color W(%� Comments � Sod/or anics loose moist �ark . .. .... ............9........ -............ -� - .... . . rown 1 SM Silty fine Sand w/gravel ���� � � row� with occ. gravel to 6" �ens�em rown 10.8 2 ��-- - --- �ra�- ro n 3 .----- -� � ..................... .................. � � - - ... 4 cemented ha e�se/ gray 8 6 5 Maximum depth 4.5 ft. 6 No ground water encountered. 7 GEOSPECTRUM CONSULTANTS, INC. Proposed Residential Development }�, ; � :�-1 '�<:_;:�, 3517 & 3603 NE 7th Street Geotechnical En rneerir ard �.a��h ���ences Renton, WashingtOn Proj. No. 13-103 Date 3/13 Figure A-4 4 � TEST PIT NO. 9 Logged by JAD Date: 1/31/13 Elevation 408' Depth Blows Class. Soil Description Consistency Moisture Color W(°/a) Comments 0 � ....... ..Sodforganics................................ loose moist ray SM Silty fine and w/ r el �ark brn , ........ ......... -- .......... � occ: bo�u��e�to 12" dens�em brown �2 2 2 &abundant roots to 3" � ... .......... ...._ ....1........................ �o�vn ................... ............ -- 3 ha dnsel gray � � 4 Maximum depth 3.5 feet. 5 No ground water encountered. 6 7 GEOSPECTRUM CONSULTANTS, IIVC. Proposed Residential Development �i�g; 3517 & 3603 NE 7th Street Geotechnica!Engineering and Earth Sciences Renton, WBshington Proj. No. 13-103 Date 3113 Figure A-5 �1"��,��, t ���.�".�,'�� ����'��� �����'�������.�����,� .�'�ti�� .� .��� .� �� , .� ��� -- - �� �: � _:.��;,:�����a��c�l �E��gin ��rin� �x��d �.�r�f� �:si�r� �r�.w� ; March 18, 2013 Mr. Kyle Miller KRRV Development, LLC ' P. O. Box 908 � � Ravensdale, WA 98051 I ; ! SUBJECT: GEOTECHNICAL EVALUATION � Proposed Residential Development 3513 NE 7th Street Renton, Washington Project No. 13-106-01 Dear Kyle, ' ' This report presents the results of our geotechnical evaluation for the site of your proposed new residential development on the subject property. The purpose of our � work was to provide geotechnical engineering evaluations of the site and geotechnical ' recommendations for the residential development including design of foundations, site ' grading, site drainage and erosion control. Our work was performed in accordance with the scope and conditions of our proposal dated February 11, 2013. � ; A site topographic map and preliminary development plans (see Figure 2) were � ' provided to us and was used as a reference for our evaluations. Based on our review of � ' the plans provided and discussions with you, we understand that the property will be f divided into 4 lots and the development will include a new 2-to 3-story wood-frame residence on each of the new lots. The struct�ares will include ground level garages ; which will have slab-on-grade floors and the remainder of structures may have raised ; i floors with crawl space or slab-on-grade. ! � � We assume that bearing wall loads will be in the range of about 2 to 3 klf and maximum ' ; column loads to be in the range of about 10 to 20 kips. If actual structural loads exceed � � the above values by more than 25%, this office should be notified. � Review of the Renton online Sensitive Areas Maps indicates that the property is not i indicated to be within a Landslide Hazard, Erosion Hazard, Seismic Hazard or Cval ' ' Mine Hazard area. � ; ; ; � � � � � � ; :`-'.�.�. �ox276, Issaquah, b1/�1 93027-027c5 • Phone: (425)391-�1228 Fax: �425) 397�=i2�& ,KRR`J Development, LLC March 18, 2013 SCOPE OF WORK Our geotechnical evaluation included review of geologic mapping, site explorations, engineering analyses and evaluations and the preparation of this report. The scope of work included the following specific tasks: o Review of published geologic mapping of the site vicinity and our recent explorations on the adjacent property to the east. o Performed a reconnaissance of the site as well as observations of the adjacent developed lots to the east. o Observed and logged three test pit explorations on the site (see Figure 2) to depths up to 4 feet below existing ground. Logs of the test pits and results of field and laboratory testing are presented in the Test Pit summaries of Appendix A along with logs of adjacent explorations on the adjoining property to the east. o Performed geotechnical engineering evaluations of the proposed site development and developed our geotachnical recommendations for foundation design and site grading. o Prepared this geotechnical report summarizing our findings and recommendations. OBSERVED SITE CONDITIONS I The property is bordered on the west, south and east by developed residential Iots (we , are currently performing a geotechnical evaluation for new development of the next two lots to the east. At the time of our field exploration the property was developed with a I residence an� three out buildings as shown in Figure 2. The topographic mapping included on the site plan of Figure 2 indicates that the property generally slopes very gently down to the west/southwest at gradients that range from only about 4 to 7 percent in localized areas and overall average gradients across the property range from about 4 to 5 percent with a maximum elevation difference across the property of about 8 feet from northeast to southwest. The site was well vegetated primarily with gras�es but also included shrubs, fruit trees and evergreen trees up to about 4 feet in diameter. We did not observe any seeps or springs or evidence of current or past erosion on the � site. Project No. 13-106-01 Page 2 . KRR`ar Development, LLC March 18, 2013 Subsoils Our evaluation of the subsurface conditions was based on our observations of three exploratory test pits within the property plus review of our own three exploratory test pits excavated within the adjoining property to the east (Project 13-103-01) as well as review of published geologic mapping. Approximate locations of the onsite test pits and the previous adjoining test pits are shown on Figure 2. Logs of the onsite test pits and the previous adjoining test pits are presented in Appendix A. Subsoils encountered in our test pits were found to include some minor fill and natural glacially consolidated soils. Fill soils were encountered in TP-1 (of Project 13-103-01) located at the northwest corner of the adjoining property to the east. Fill soils were silty very fine sand with occasional gravel and were only about 1 foot thick at that location. Natural soils encountered at the test pit locations were generally silty fine sand with gravel. The upper soils were typically loose to medium dense soils to depths of about 2 to 3.5 feet below the natural surface becoming �ery dense and hard and cemented at greater depths. Ground Water � No ground water or seepage was observed in any of the test pits. Typically the shallow soils were classified as moist to very moist and the deeper cemented soils were classified as moist. The measured moisture contents of the soils generally ranged from about 8 to 16 percent. Subsurface Variations Based on our experience, it is our opinion that some variation in the continuity and depth of subsoil deposits and ground water levels should be anticipated due to natural deposition variations and previous onsite structures and grading. Due to seasonal moisture changes, ground water conditions should be expected to change with time. Care should be exercised when interpolating or extrapolating subsurface soils and ground water conditions between or beyond our test pits. . .:;:,... , ,... .. , .,.. .. � �yy v ', � .KRR�f Development, LLC March 18, 2013 SITE EVALUATIONS General The referenced geologic map of Figure 1 indicates the site vicinity to have surFace exposures of glacial till (Qgt) soils. The Qgt glacial till soils are highly consolidated, heterogeneous mixtures of sand, silt, clay and gravel soils deposited during the advance of the Vashon glaciation, the last glacial advance into the Puget Sound area, approximately 13,000 to 16,000 years ago. Based on the soils observed on the site and review of the referenced map, it is our opinion that the natural very dense/hard silty sand with gravel soils underlying the property and are most likely glacially consolidated till deposits (Qgt). I Based on the results of our field investigations combined with our own experience and judgment, it is our opinion that the geotechnical site conditions are suitable for the proposed development provided our recommenc+ations are followed. Hazard Assessment Landslide: The Renton Sensitive Areas Maps indicate the site is not within a Landslide Hazard area. In addition, the geologic map of Figure 1 indicates no mapped landslides within the site vicinity and our site observations indicate the site is currently stable. Considering the very gentle slope gradients and the observed glacial till soils, it is our opinion that the potential for future instability on the site is very low to nil. Erosion: The Renton Sensitive Areas Maps indicate the site is not within a Erosion Hazard area. We observed that the site is well vegetated we observed no indication of any seepage or concentrated water flow or current or past erosion on the site. Based on our site observations and explorations it is our opinion that there is no unusual erosion risk at this site and any potential erosion potential resulting from development will be mitigated by our recommended grading procedures and drainage/erosion control measures and by final re-vegetation/landscaping incorporated into the proposed development plans. Coai Mine: The Renton Sensitive Areas Maps indicate the site is not within a Coal Mine Hazard area. � Seismic: The Renton Sensitive Areas Maps indicate the site is not within a Seismic � Hazard area, however the Puget Sound region is a seismically active area. About 17+ moderate to large earthquakes (M5 to M7+) have occurred in the Puget Sound and � northwestern Cascades region since 1872 (141 years) including the 2/28/01 M6.8 Nisqually earthquake and it is our opinion that the proposed structures will very likely experience significant ground shaking during their useful iife. Project No. 13-106-01 Page 4 ,KRR�• Development, LLC March 18, 2013 i I Based on a recentiy published study the site lies only about 2.5 miles south of the southern mapped location of the Seattle fault and about 18 miles southwest of the estimated trace of the South Whidbey-Lake Alice fault both of which have postulated maximum credible magnitudes of 7.0 to 7.5. Another recent study of the Vashon- Tacoma area presents evidence for the east-west trending Tacoma Fault which is indicated to pass through the south end of Vashon and the middle of Maury Island about 10.5 miles southwest of the site. The study suggests that the Tacoma Fault and the Seattle fault may be linked by a master thrust fault at depth. i The Seattle fault has been documented to have moved at its west end (Bainbridge Island) about 1000 to 1100 years ago and evidence of movement at the east end has also recently been documented. Some experts feel that the recurrence interval between large events on the Seattle Fauft may be on the order of several thousands of years but our calculations indicate it may be on the order of 1200 to 1400 years. The activity of the documented Tacoma fault is considered to be on the same order as the Seattle fault. The recurrence of a maximum credible event on the South Whidbey fault is not known but some experts have assigned a recurrence of about 3000 years, however smaller events will occur rnore frequently as evidenced by the 5.3 event on � May 2, 1996 which was attributed to that fault. I In addition to Puget Sound seismic sources, a great earthquake event (M8 to M9+) has I been postulated for the Cascadia Subduction Zone (CSZ) along the northwest Pacific � coast of Oregon, Washington and Canada. The current risk of a future CSZ event is 'I not known at this time. Published reports have indicated recurrence intervals for a CSZ event to range from as little as 100-200 years to as long as 1000+ years and the time of the last event is reported to have been about 313 years ago. The 2009 )nternational Building Code (IBC) acopted by the City of Renton requires consideration of a spectral acceleration level with probability of exceedance of 2 percent in 50 years for seismic structural design. This corresponds to about a 2475- year recurrence interval earthquake ground motion. Based on the short period spectral response accelerations presented in Figure 1613.5(1) of the 2009 IBC, adjusted as per equations 16-36, 16-38 and factored as per section 1803.5.12(2), we estimate the IBC peak ground acceleration far soils and foundation design at this site to be about 0.38g. Please note that the 0.38g peak ground acceleration includes the additional reduction factor of section 1803,5.12(2) and is not intended for structural analyses. NJ� recommend the site be considered a Site Class D for structural design. Secondary seismic hazards due to ea�thquake ground shaking incluc.:� ., �.,;:,�u ,,,��� failure, liquefaction, lateral spreading and ground settlement. Considering the very dense/hard nature of the soils recommended for bearing at the site, it is our evaluation that the potential for damage to the structures due to liquefaction, lateral spreading and settlement is very low to nil. The potential for seismical(y induced shalfow failures is also considered very low to nil. Project No. 13-106-01 Page 5 � KRRV' Development, LLC March 18, 2013 Structure Support Considerations in our opinion the undisturbed very dense/hard natural glacial tiil soils encountered in our explorations should pravide good support for the proposed structure foundations. Bearing soils are expected to be encountered at depths ranging from about 2 to 3.5 feet below the natural ground surface at the site. Foundations should penetrate through any existing fill, topsoil and loose/medium dense soils to bear on undisturbed very dense/hard natural soils. Conventional spread footings are considered appropriate for support of the proposed structures considering that bearing soils are at shallow depths. However, if any deep fill areas are encountered on the site, lean concrete footing extensions or pipe piles could be used to transfer foundation loads to the deep bearing soils in those areas. We have included recommendations for spread footings and pipe piles in this report. RECOMMENDATIONS The following subsections present our recommendations for design of foundations, site grading, drainage control and erosion control. Also included are recommendations for plan review and observations and testing during construction. Spread Footinq Foundations Conventional spread footings founded on undisturbed very dense/hard natural glacial till soils should provide good support for the proposed structures. Bearing soils are expected to be encountered at depths ranging from about 2 to 3.5 feet below the natural ground surface of the site. Continuous wall footings should be at least 18 inches wide. Square footings for column support should be at least 24 inches wide. Footings supported on undisturbed very dense/hard natural glacial till soils may be designed based on an allowable bearing pressure of 2000 psf. ' All footings should be founded at least 18 inches below the lowest adjacent final grade. Where the natural bearing soils slope, the footing excavation should be stepped to maintain a horizontal bearing surface. If deep fill �r other unsuitable soils are encountered, foundation loads may be , transferred from the recommended minimum foundation depths to the recommended I very dense/hard bearing soils by a monolith of lean concrete having a minimum compressive strength of 1000 psi. The width of an un-reinforced lean concrete I monolith should be at least as wide as the footing or at least one-third of the monolith height, whichever is greater. Reinforced monoliths should be designed by a structural engineer. A suitable width trench should be excavated with a smooth edged excavator ' Project No. 13-106-01 Page 6 ,KRRV Development, LLC March 18, 2013 bucket (no teeth) to expose the dense/very dense bearing soils under observation by our office and backfilled as soon as possible with the lean concrete to the footing elevation. . The estimated settlement of a 18-inch wide continuous footing carrying a load of 3 kips per foot is on the order of 1/4 to 1/2 inch. Our settlement estimates assume that foundations are supported on undisturbed very dense/hard natural bearing soils and that all fill and loose/disturbed material is removed from the bearing surface prior to concrete pour. Maximum differential settlement within the proposed structures is expected to be 1/2 inch or less. Settlements are expected to occur primarily during construction. Resistance to lateral loads can be assumed to be provided by friction acting at the base of foundations and by passive earth pressure. A coefficient of friction of 0.45 may be assumed with the dead load forces in contact with on-site soils. An allowable static passive earth pressure of 250 psf per foot of depth may be used for the sides of footings poured against undisturbed medium dense natural soils or properly compacted structural fill. An allowable static passive earth pressure of 150 psf per foot of depth may be used for the sides of footings or grade beams poured against existing loose soils. The vertical and lateral bearing values indicated above are for the total dead load plus frequently applied live loads. For short duration dynamic loading caused by seismic or wind forces, the ve�tical bearing values may be increased by 50 percent and allowable lateral passive pressures may be increased by 33 percent. Driven Pipe Pile Foundations If deep fill or other unsuitable soils are encountered, foundation loads may also be transferred from the recommended minimum foundation depths to the recommended very dense/hard bearing soils by properly constructed pipe piles. This type of support is constructed by driving 2-inch or 3-inch diameter steel pipe to refusal into the bearing soils below existing unsuitable soils. Based on our experience, piles typically penetrate about 5 to 15 feet into the bearing soils before encountering refusal. Refusal penetration rates for piles will depend on the hammer size and the load testing results. Refusal penetration rate for a 3-inch pile driven with a tractor-mounted 6501b hydraulic hammer typically should be in the range of about 15 to 20 seconds per inch. Refusal penetration rate for a 2-inch pile driven with a tractor-mounted 6501b hydraulic hammer typicaliy should be in the range of about 8 to 10 seconds per inch. Alternatively 2-inch piles may be driven using a 901b jack hammer plus the weight of the operator or using a 140+fb rinho-type pile-top pneumatic hammer to a refusal penetration rate of 1 inch or less per minute. We recommend that all pile instailation and pile load tests be observed by our office to verify the allowable capacity and refusal criteria for the production piles. Project No. 13-106-01 Page 7 tKRRV Development, LLC March 18, 2013 An allowable vertical downward capacity of 6 kips (Factor of Safety = 2+) may be assumed for 2-inch diameter piles and capacities of 10 kips (Factor of Safety = 2+) can generally be assumed for 3-inch diameter piles installed as recommended above. No uplift capacity or lateral support should be assumed for driven pipe piles. No lateral support should be assumed for the pier shafts. Resistance to lateral loads can be provided by battered piles (compression only) and by passive earth pressure against the sides of grade beams. An allowable static passive earth pressure of 150 psf per foot of depth may be used for the sides of grade beams poured against existing loose soils. Capacity may be limited by the structural capacity of the pipe and connections which should be determined by the structural engineer. The pipe and couplers which form the pile, must be of structural quality (schedule 40+) and must be provided with a corrosion resistant coating (galvanized). The pipe pile supports should be capped with a grade beam to transfer structural loads to the piles. The pile/grade beam system should be designed by a qualified structural engineer. Site Gradinq Site grading is expected to consist primarily of excavation for proposed foundations and subgrade preparation for slab and pavement areas and utility trenches. Onsite granular soils cleaned of debris and organics are considered suitable for use in general compacted fills but in our experience the onsite glacial till soils will be moisture sensitive with regard to grading and compaction characteristics. Grading should be scheduled for the late summer months if possible. Wet weather grading may require the use of impo�ted clean granular fill soils which are more easily compacted at highe� moisture levels. Recommendations for site preparation, temporary excavations structural fill, subgrade preparation, site drainage and trench backfill are � below. Site Preparation: Existing vegetaticn, debris fiil �oils, and loose or organic natural soils should be stripped from the areas that are to be graded. During rough grading, excess soils may be stockpiled for later use. Stripping in subgrade areas is expected to average about 1 foot. Soils containing more than 1% by weight of organics may be used in planter areas, but should not be used for structural fill. Stumps, debris and trash, plus rocks and rubble over 6 inches in size, should be removed from the site. Subsoil conditions on the site may vary from those encountered in our test pits. Therefore, our office should observe the prepared areas prior to placement of any new fills. Temporary Excavations: Sloped temporary construction excavations may be used where planned excavation limits will not undermine existing structures or interfere with other construction. Where there is not enough room for sloped excavations, shoring should be provided. Project No. 13-106-01 Page 8 , KRR`,✓ Development, LLC March 18, 2013 Based on the subsurface conditions encountered in the test pits, it is our opinion that sloped temporary excavations may be made vertically to depths of 4 feet or less. Excavations up to 10 feet in depth should be sloped no steeper than 1:1 within looselmedium dense sails and no steeper than '/2:1 (horizontal:vertical) within the un- weathered, hard natural glacial till soils. It should be noted that the contractor is responsible for safety and maintenance of constiuction slopes. We recommend that cuts over 4 feet in depth be covered with visqueen tarp to help control ravelling and sloughing. Surface drainage should be directed away from the top edge of cut slopes. Surcharge loads should not be aliowed within 5 feet of the top of the slope or within a 1:1 (horizontal:vertical) plane extending up from the toe of excavation, whichever is greater. Structural Fill: Provided that soil moisture can be reduced and maintained near optimum, excavated onsite soils cleaned of organics and debris may be used for general structural fill but the onsite soils are expected to be moisture sensitive and during the rainy season the soils may become too wet for practical compaction. Therefore imported granular fill soils should be used if moisture conditions cannot be adequately controlled. Loose soils, formwork and debris should be removed prior to placing fill or backfill. Structural fill should be placed in horizontal lifts not exceeding 8 inches in loose thickness and compacted to at least 90 percent of the maximum dry density as determined by the ASTM D1557 test methad. Imported granular fill should consist of clean, well-graded sand and grave! materials free of organic debris and other deleterious material. Imported material for wet weather grading should be a sand/gravel mixture with less than 5 percent fines based on the ��3t1C� if�CflOf�. SlabiPa��t�7,�nt Supc;ort: �,a�s-��r-grade �n,� pa�rer���r�t snculd t�e ��:pport�d ,.:r�;�.ly ��n undisturbed dense natural soils or on properly compacted structural fill over medium dense natural soils. Where unsuitable soils (existing fill, loose and organic soils) exist at subgrade level, subgrade preparation should include excavation of the unsuitabie soils as required to expose medium dense natural soils or to a maximum depth of 2 feet (or deeper as required to remove all organic soils where organic soil depths exceed 2 feet below final subgrade) and placement of structural fill to final subgrade elevation. Subgrade fill should be placed in accordance with the recommendations for structural fill except that the top 6 inches of the subgrade fill should be compacted to at least 95 percent of the ASTM D1557 maximum dry density in pavement and driveway areas. It should be noted that where the proposed slabs cross a fill/natural contact line, there will be a high risk of cracking. Risk of cracking can be reduced by placing construction joints at the contact and by proper steel reinforcement of the slab. Interior concrete Project No. 13-106-01 Page 9 .KRR�;r Development, LLC March 18, 2013 slabs should be underlain by a capillary break consisting of a polyethylene vapor barrier of at least 6 mil thickness. Utility Trenches: Buried utility conduits should be bedded and backfilled around the conduit in accordance with the project specifications. Bedding material should extend from six inches below the pipe to six inches above the pipe. Where conduit underlies pavement or slabs-on-grade, the remaining backfill above the pipe should be placed and compacted in accordance with the recommendations for structural fill. If imported granular fill is used for trench backfill it should be capped with 12 inches of onsite silty soils. Drainaqe Control Surface drainage from the site and adjoining upslope areas should be controlled and diverted around the development area in a non-erosive manner. Adequate positive drainage ,should be provided away from the structures and on the site in general to prevent water from ponding and to reduce percolation of water into subsoils. Granular backfill should be capped with paving or 6 inche;� of onsite silty soils. A desirable slope for su�fiace drainage is 2% in landscaped areas and 1% in paved areas. Roof drains should be tightlined into the storm drain system (no discharge on the ground surface). A permanent perimeter drain, independent of the roof drain system, should be placed adjacent to the base of the continuous exterior foundations. The drain should consist of a four-inch diameter perforated PVC drain pipe placed in at least one cubic foot of washed drain gravel per lineal foot along the base of the foundations. The drain gravel zone around the pipe should be encapsulated with a membrane of Mirafi 140 filter fabric or equivalent between the drainage zone and onsite silty soils. Erosion Control � Although we observed no evidence of erosion, onsite soils are expected to be erodible � when disturbed and exposed to concentrated water flows. Siltation fences or other detention devices should be provided around the downslope side of the disturbed site , area and soil stockpile areas during construction to control the transport of eroded material. The lower edge of the silt fence fabric should have "J" shaped embedment in I a trench extending at least 12 inches below the nround surface. , I Surface water flow should be collected in area drains and tightlined to the storm water system, no water should be discharged on the site unless via a properly designed and approved infiltration/dispersion system. Exposed final graded soil areas should be � planted immediately with grass and deep rooted plants. � Project No. 13-106-01 Page 10 .KRR� Development, LLC March 18, 2013 Plan Review This report has been prepared to aid in the evaluation of this site and to assist the architect, structural and civil engineers in the design and construction of the project. It is recommended that this office be provided the opportunity to review the final design drawings and specifications to determine if the recommendations of this report have been properly implemented and to make any supplemental design recommendations which may be required. Observations and Testinq Durinq Construction Recommendations presented in this report are based on the assumption that soil conditions exposed during construction will be observed by our office so that any necessary design changes or supplements may be made. Foundation excavations should be observed to verify that they expose undisturbed very dense/hard bearing soils and that excavations are free of loose and disturbed materials. All pile installation and testing should be observed by our office to confirm the allowable design capacities. Refusal criteria for all driven pipe piles should be confirmed by our office. Surface and subsurface drainage provisions should be verified by our office. All structural fill and slab/pavement subgrade areas should be observed by a representative of this office after stripping and prior to placing fill. Drainage control systems should be observed by our office to verify proper construction. Proper fill placement and compaction should be verified with field and laboratory density testing by a qualified testing laboratory. . I Project No. 13-106-01 Page 11 �KRR� Development, LLC March 18, 2013 CLOSURE This report was prepared for specific application to the subject site and for the exclusive use of KRRV Development, LLC and their representatives. The findings and conclusions of this report were prepared with the skill and care ordinarily exercised by local members of the geotechnical profession practicing under similar conditions in the same locality. We make no other warranty, either express or implied. Variations may exist in site conditions between t►�ose described in this report and actual conditions encountered during construction. Unanticipated subsurface conditions commonly occur and cannot be prevented by merely making explorations and performing reconnaissance. Such unexpected conditions frequently require additional expenditures to achieve a properly constructed project. If conditions encountered during construction appear to be different from those indicated in this report, our office should be notified. Respectfully submitted, GEOSPECTRUM CONSULTANTS, INC. 4 � / �•,\ L�� c S pt.. D Op1 � ti wast ;; .%� James A. Doolittle "� �,5� �oF �i, Principal Engineer -�Q'y� ��� := •� .r � 1�" �3 ... :;�;,f��� r, yj.�. Encl: Figures 1 and 2 �'���� Appendix A `�'� �� �{�r�.:�� ,�� y .y� i�y ^J'`'`�`i-;'J,!.,=' � � +c: �I ../ Dist: 2/Addressee E��'a�' �'�' 20� � Project No. 13-106-01 Page 12 � � i� � . . �... � � i� .� s� tir�r� ! '�l♦rJ�,!��; 1 1�'` �' � j�\ '' 1 . .. �'�' � —�� ���,�v� .�i�`>�`�����'�- I - �. �� ' ..'1 (' .j � I� � � I f��� .� �` . �`, � �. J • �,_�_�' + ` c\*!�)1���. � � I� � ' , ri �•rt�s����•�� .��� •-.�• � . �' '- [ -F�� �t �_�.��`� �.lij . .. �� . � ��"�� ` -. R �'I ■ . . .. '�+, � ���.u��r�` � . 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Gootochnfco/Eng/noaring ond F_o�th Sc/oncos Proj. No.13-106 Date 3/13 Figure 2 � ' APPENDIX A FIELD EXPLORATION Our field exploration included a site reconnaissance and test pit explorations. During the site reconnaissance, the surface site conditions were noted, and the locations of the test pits were approximately determined. The test pits were approximately located using the existing structures as a guide. The approximate locations of the test pits are shown on Figure 2. Test Pit elevations were estimated based on the topographic mapping shown on Figure 2. Test pits were advanced using a trackhoe excavator. Soils were continuously logged and classified in the field by visual examination, in accordance with the ASTM Soil Classification system. Logs of the on-site test pits are presented on the test pit summary sheets A-1 and A-2. Logs of test pits from the adjacent property to the east (our Project No. 13-103-01) are included on Figures A-3 and A-4. The test pit summaries include descriptions of the soils and pertinent field data. Soil consistency and moisture conditions indicated on the logs are interpretations based on the conditions observed in the field. Boundaries between soil strata indicated on the logs are approximate and actual transitions between strata may be gradual. � ' TEST PIT N4. 1 Logged by JAD Date: 2/13/13 Elevation: 400' Depth Blows Class. Soil Description Consistency Moisture Color W(%) Comments � loose moist �ark ........ ......�.................._....9--�- ��---.......... SM Sil fine Sand wlor anics& roots rown � .......-� .........................�----....... - ............. ................ SM Silty fine Sand w/gravel light brown 10.1 Z - � -- -� -...- �ens�em ��o�vn 8.2 3 .._ ._........... dense c�emented. . _ - - --ha dnsei g�aY - - 7.9 4 5 Maximum depth 4 feet. 6 No ground water encountered. 7 TEST PIT NO. 2 Logged by JAD Date: 2/13/13 Elevation: 399' Depth Blows Class. Soi! Description Consistency Moisture Color W(%) Comments � . ....... ..Sod.................................. . . - loose moist dark � SM__. __Silty.fine Sand w/organics.&.roots brown SM Silty fine Sand w/gravel ��qht & fine roots °W� 2 ' 11.2 3 ........ . . .......................- - --�m:d�rsse� . . . ..cemerite. .......................... ...v:-d��risel". ......_..- � 8.8 4 5 Maximum depth 4 ft. 6 No ground water encountered. 7 GEOSPECTRUM CONSULTANTS, INC. Proposed Residential Development � �:: F � �:� �7�= 3513 N E 7th Street Geotechnical En ineer,�r�a acd Ear;n �����enc�s Rentoll, WaShin tOtl Froj. No. 13-106 Date 3/13 Figure A-1 � ` TE�T PIT NO. 3 Logged by JAD Date: 2/13/13 Elevation 403' Depth Blows Class. Soil Description Consistency Moisture Color W(%) Comments 0 --...... ..Sodlorganics................................ loose moist ra SM Silty fine Sand w/gravel to 3" �ar�C brn � .brown 13.5 2 .----...... .......... �ense Se� �o�rvn ..-�...................... .......... ....... ........... - - 3 v.dense/ gray cemented hard 8.6 4 Maximum depth 3.5 feet. 5 No ground water encountered. 6 7 I GEOSPECTRUM CONSULTANTS, (NC. Proposed Residential Development , :�;� F � 3513 N E 7th Street Geotechnrcal Engrreen,nq ar,d Er����� ��`e���e� Renton, Washington Proj. No. 13-106 Date 3/13 Figure A-2 � ' TEST PIT fVO. 1 Logged by JAD Date: 1/31/13 Elevation: 406' Depth Blows Class. Soil Description Consistency Moisture Color W(%) Comments � SM Silty fine Sand w/occ gravel loose moist dk brn FILL ............... 1 brown ......... ...... ......................................... ............... ......._....... .. ... SM Silty fine Sand w/occ gravel medium brown dense 2 to dense moist/ �ed- 16.5 ve rown 3 ..mo�st........ .. �- � very moist gray w/some cementation da� e/ 9 4 5 Maximum depth 4 feet. 6 No ground water encountered. 7 TEST PIT NO. 2 Logged by JAD Date: 1/31/13 Elevation: 403' Depth Blows Class. Soil Description Consistency Moisture Color W(%) Comments � SM Silty fine Sand wlorganics loose moist �ark rown --...- ..... . ...............� -......................... to ............. 1 SM Silty fine�and brown wi h occ. gravel to 6" very moist 13.4 2 ...m:d�nse-. 3 �cemented-.. - . � -- . . v: de�rrsel m�tst- 4 5 Maximum depth 3.5 ft. 6 No ground water encountered. 7 GEOSPECTRUM CONSULTANTS, 11VC. Proposed Residential Development -- t�� �` � 3517 8� 3603 NE 7'h Street � .,a.�,s':�: Geofechnical En ineerin and Earth Sciences Renton, Washington Proj. No. 13-103 Date 3/13 Figure A-3 � ' TEST PIT NO. 3 Logged by JAD � Date: 1/31/13 Elevation: 400' Depth Blows Class. Soil Description Consistency Moisture Color W(%) Comments � SM Silty fine Sand wlocc gravel loose moist dk brn ......... & abundant roots to 4" to brown 1 very moist 15�8 2 .......--��- --.... --- -�-----.... �ens�em �o�ivn 3 ......................� -......... ........----.._.... ..... - ........... .....-�-- ----- very moist gray w/some cementation hanse/ 9 6 d 4 5 Maximum depth 4 feet. 6 No ground water encountered. 7 TEST PIT NO. 4 Logged by JAD Date: 1/31/13 Elevation: 405.5' Depth Blows Ctass. Soil Description Consistency Moisture Color W(%) Comments � Sod/or anics loose moist _dark brn - ..9........................................ 1 SM Silty fine,�Sand t� brown wi n gravel to 3" very 2 .................. moist .............. �ens�em el�own 10.5 i� 3 cemented........ . . .. .. .. ...v:d��risel.. . moist... ... g�ay . 8.4 4 5 I Maximum depth 4 ft. 6 No ground water encountered. � 7 GEOSPECTRUM CONSULTANTS, INC. Proposed Residential Development ' ` '�. � _' 3517 & 3603 NE 7�h Street - �:: ,' �=� Geotechnrcal En rneer�r,� , ; �=���n Renton, Washington Proj. No. 13-103 Date 3/13 Figure A-4 � � . -.�r-"`.�;�' I DEPARTMENT OF COMMUNITY --^-�.�clry of- . � . ���: AND ECONOMIC DEVELOPMENT �� ��. �_ I '� �.� i � ���;y �:; _ �. j ADMINISTRATIVE SHORT PLAT REPORT & DECISION A. SUMMARYAND PURPOSE OF REQUFST � REPORT DATE: J u n e 4, 2013 I� Project Narne: NE 7th West Short Plat I� Project Number: LUA13-000496;SHPL-A � �'I. , Project Manoger: Elizabeth Higgins, Senior Planner Owner: Arthur and Gertrude Stirn• 3513 NE 7th St- Renton WA 98 , , 056 Applicont: Kyle Miller; KRRV Dev, LLC.; P.O. Box 908; Ravensdale WA 98051 Contact:. Darrell OfFe; Offe Engineers; 13932 SE 159th PI; Renton 98058 Project Location: 3513 NE 7th St; Renton WA 98056 Project Summary: The applicant has proposed subdividing a 0.66 acre property, located at 3513 NE 7th St, in the Highlands neighborhood of Renton, into 4 lots suitable for single-family residential development.The proposed action, a short plat, is an administrative process. The property is designated Residential Single Family in the City of Renton Comprehensive Land Use Plan and zoned Residential 8 (R-S). The proposed development density ': 7.7 dwelling units per net acre. Exist. Bldg. Area SF: N/A Proposed IVew Bldg. Area N/A (footprint): Proposed IVew 8/dg.Area (gross): N/A Site Area: 28,657 gsf(0.66 Total Building Area GSF: N/A acre) � i i i i. 1 4 — �:w � ' U,.. �I � _---,�� I�s �`�� ' ✓�5;.0 3E�n - � �� � t � ��� (e��.�� ,. ; ' I �_�, _ ; - � � � -- — — — � � �� �E�2 � �'�' � �? � _ - - _ _�--� .��� � � . .. . . . _, . _ .. . . �-i . � -j.-' �_ �a! ' �,— — — � c � � + `u 17��,; �� -- ? — F ry �s_ ' S _ rt _--'.� _ `n _ .a ° �' � � _ . ,--i �°0 - _ ro '.,�,�: .� - _ _�_,� ��' `� so', — i., i� -: ; � ���-31�, i '�.. �- �� �. -�s �..-3X�� :�. Sr^ _ � . � � :n, �- � � �'� �. i - `� ; I �.w ,�� SE ��n�-i — `� ::.�.:� �" 3�. --.�"`� y, _ �Fhii%. 1 .5 � � '.- . ' r�' �.. -b� � � _ i �----� 6� v ��! ' '= L _ — � II a='.3, _ ts .�p � _ __ ,� ' — _— ' _ JI _� __ �� .p' q-�°1'— � .. �. � J ` �5,p . . _`7 _ P ,�.r s �_I �,r`_���� L�,�dl, j 3�.. 2=1�� .ib��ld1Kl�,a { D�� •�� j�'S� � �� � L- I r I p- , � ��s'��� �� '` �r�` .z�'1"=i _ I- �� titi' ��`` l� =-�-T � �`� �,� � -- F - � .�.�`,�.���.��"r `_ — '�� ��� `�`�! ` `� E6�� �" I � �' �"�,- g, , �- �'�� - � ,�''� _—z �,��� ' �` `� 'y�'�`.�� �+�- � —i � x � c . '3� - -'� �'.,,. o _ S+ - 2 �..� 3.3 "t'-�� �E'" /� � �a' `, � .��f� , � u5n � '��.�I���,E.�i��GfS: _'i . �.i ��"-.� '`.r�.����s��,�� rt� ..������ Ii�I�.���lE�i� Project Location Map Short Pfai Report 13-000496 Ciiy of Renton Department of Community& Economic Deve(opment Administrotive Short Plat Report& Decision 11:F 7TH tiVEST SHORT PLAT LUA23-000496;SHPL-A Report of June 4, 2013 Page 14 of 17 4. The proposed NE7th West Short Plat complies with the street standards as established by City Code, provided the project complies with all advisory notes and conditions of approval contained herein. K. DECISION: The NE 7th West Short Plat, File No. LUA13-000496; SHPL-A, is approved, subject to the following condition: l. The private road {Olympic Court NE) shall be required to extend from the proposed hammerhead eastward to the east property line, forming a looped private roadway with the private road of the proposed neighboring short plat at 3517 NE 7th Street, LUA13-000514. Maintenance of the private road and abutting landscaping shall be by the underlying property owners of the easement area. DECISION ON LAND USE ACTION: SIGNATURE: , � �, La�3 C.E. "Chip"Vincent, CED Administrator ate TRANSMITTED this 4th day of lune, 2013 to tlte Contact/App(icant/Owner(s): Contod: Applicant: Owner(sJ: Darrell Offe Kyle Miller Arthur&Gertrude Stirn Offe E'ngineers KRRV Dev., LLC 3513 NE 7th Street 13932 SE 159`h Place PO Box 908 Renton, WA 98056 I Renton, WA 98058 Ravensdole, WA 98051 TRANSMITTED this 4th day of lune, 2013 to the Party(iesJ of Record: � Mike Moran Bob Gevers 671 Pierce Court NE 900 Kirkland Avenue NE Renton, WA 98056 Renton, WA 98056 TRANSMITTED this 4th day of lune, 2013 to the following: Neil Watts, DevelopmentServicesDirector Kayren Kittrick, Development Services Jan Conklin, Development Services � Carrie Olson, Development Services lennifer Henning, Current Planning Fire Marshal Renton Reporter Short Plat Report 13-000496 • y_ r Section 7: Other Permits None applicable at this time I Section 8: CSWPPP Analysis and Design The proposed development consists of 1.91 acres of developed area. A DOE NOI and SWPPP will be required by the developer prior to start of clearing and grading. An Erosion Control Plan has been included within the utility construction permit submittal. This plan will be approved and included within the construction permit issued by the City of Renton. � f Section 9: Bond Quantities, Facility Summaries, and Declaration of Covenant These documents will be prepared and provided at the time of Construction Plan submittal to the City of Renton. At this time, the storm system and analysis provides for a conceptual system that will be finalized during civil plan preparation. . Section 10: Operation and Maintenance Manual The Operation and Maintenance Manuals will be prepared and provided at the time of Construction Plan submittal to the City of Renton.