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Home My WebLink About03076 - Technical Information Report TECHNICAL INFORMATION REPORT (STORM DRAINAGE) FOR � FIRE STATION #12 Submitted by ESM Consulting Engineers, LLC 720 South 348`h St. Federal Way, WA 98003 253.838.6113 tel 253.838.7104 fax �:.�� , � � � ��: � www.esmcivil.com CITY OF FE�?�^� RECEIVED sEP > > 2aoz �iIIl7�NG D,�4�iS,r�R,, i � I � � � TECHNICAL INFORMATION REPORT (Storm Drainage) FOR FIRE STATION #12 CITY OF RENTON WASHINGTON Prepared For: City of Renton and Rice Fergus Miller Fire Department Architecture 8� Planning 1055 S. Grady Way 262 4�' Street Renton, WA 98055 Bremerton, WA 98337 (425) 430-6400 (360) 377-8773 Prepared By: John S. Chadwell, P.E. ESM Consulting Engineers, L.L.C. 720 South 348th Street Federal Way, WA 98003 (253) 838-6113 ��oC F Was ��, O 2a�s2 � � ��cls-�ti��w�' �S�ONAL E�G August 16, 2002 XPIRES:9/2/200i i:lesmyobs19961documentltir-aug 02.doc 720 South 348th Street Tel 12531 838 6113 Tacoma (253) 927 0619 Civi! Engineering Land Planning Federal Way. WA 98003 Fax 12531 838 7104 Seattle(2061 623 5911 Praject Management Public Works www.esmcivil.com 8remerton(360)792 3375 Land Surveying �•�'J6-02 06: 06P Rice Fergus Miller 360 792 1385 P _02 PLANNINGBUiLDING/PUBLIC WORKS DEYAKI�M�1v 1 �UBLIC WORKS CONSTRUCTION PERMIT APPLfCATION New Building ❑ Additioa to Existing ❑ Tenant tmpmvement (�,62 � �1 q �uo��o3� � Pra'ect Addreas: t Zo 9 le.K.LA�1 a �7 l,,v��L: 1ZE�aToN , 1ti�4- �D'�tD wortc De�cripcion: �`�i.35�'R.�'T�o V 4� f�1�hJ I 5_��O S Q• �T. ='s st�, L,,T a't 101� D,�.l � M�ZL��.NL�/ Op�R�'T�aa} GC,tJT� 1�. • ��,p��=.c.1 1S Two �ToR►'�S. TYP� g• �f Woov �F t�oN6 w/ Z8��..�, ��T�.S � w� ��wa 25 `/� t�r t,�+�� King County'Tax As.sessor Number. LoT� �j- Y� , +K�-��ri�� , t'��cw�44,cy�u.aT�.v P�T,wC:�►Tv� uk,�u►.a•�a� rlo.Z Legal Doscription: c1[��n�w.� ZD�E?�T T+��.R�oF KEI o�.v�sT� bJ �Io wM� S� oF ?LeT� ,'Pb1�C=5`j L 'tu�o�x,�et 9�, � ��.►� , ti+r 1c��c.-� c.o�,�� Wv��+�c,�Zv . Squere�ootage ot�n�re sitc 53� ZS'� �.Q FT• Lm�e�vious Ar�a �copercy owner: Gtrl oF ��*�T�•.1 Gc��T�s� Teac..y Go�L,r^�I Addresss: ��5'� �.v��c� ��z.e.o� V.Jo`� (:ity/Stste/"Gip: �G NTv,.1 , �Id► �1�� Phonelfua: `�Z5-4'�0— ro ca Z3 �= 42�i-4'�- cv�oo'S Apglicant ��LL �GQ.(,,�`� t"�� .t..L�.. Addtess: Z lo Z A�+�• e�T CirylStace/"Gip: ��v�C�'Tc�r...! Ir�d- 9��7'] Phonc/Faac: �u %�'] ��►��'`� `"� �: 3toc3 � �9L' 1 3`J� When applying for redevelopment,credit Water metcr size: Account No: InCortnation provided by U�lity Billing(425)430-6852. 1'his applicauon dv�a not constitute a pemsit to woric. W ocic is nol w commence unol a oonst[uctiou perrnit is issucd 1 cetify that the information on this application is accuratt to the bcst of my knowledge and 1 will be respor�sibie for any additios�xl fees fran er�nt valuatioa % I / �� ! ��`� �1. � �,� � " � �b/1�wc,� •9�� . Signawc�es �� . Print Name REC✓EIVED H:1GIlE.5YS1FfiM198BLDGCSW003.DOC1Dh ,�� 1 2�02 Rev 399 � �U�LDING DIVISION Sep-�6-02 06:06P Rice Fergus Miller 360 792 1385 p. O3 PUBLIC;WORKS CONSTRUC:TION P�1ZM1T 1NSPECTION/Al'PROVAL FEE CALCULA'ilOI� WORKSH�ET 50% INSPECTION/APFROVAi,F�S PER ORDiI�iANCE NO. 4345 `. !'ROJECT NAME: ��N � � �J�'=-T 1 U� �{Z 1. E,�timate tlie totat cost of of!'site and onsitc improvemenb for water lines,scwer lincs, stormwater facililies, and madway improvemcnt�for yau prajcct. Entcr estimated co�s in itema(A)through(D}below. (A) watec � f i,0o C7 (�3) Sewer S � ��c�(� (C) SW[mwater S �{'`�j UC3C7 (Includes Oa-Site Pavement)+ �K��e.rvo�7,paT�o�, <,�v�cw.��-� (D) Roadway S ��oc�c� ($�C�t,SId�V��CS.Sf�ECt�l�tbll�.tLC.� 9v�?.� 'J�T 1�.►c�-Vvr'c. STZ�:.VS� l.-1C�►�►T'�. (E} 7'otal Improvements S I '�►�,v vc� (A)+{B)+ (C)+(D)_(E 2. Calcvtaote 50%inspection/approval!ee for tWal�provements,as foliows: (1�) 2.5%vf First�100,000 of(�) S Z,�U o (G} 2%of over S I OQ{100 but S I,�c�o ^ �� lesa than 5200,OOU of(E} (!i) t_5%af over S20U,000 of(�) $ (� {1) "fotal Sd%ins�ctioNA�rpraval $ L}-,vv0 Fee: (N)+(G)+(fi)_ (1) 3. Hreakdown oC 50%Inspcction/Appraval N�ees is perfotmcd as follows: (!) 50% Water Fec S 2�� . �'�� 401/343.90.00.02 ((A} 1 {E))x{i)_{1) (K) SQ%Sewer Fee $ Zas- 7 I 401/343.90.00.01 ((B) 1 (E})x{i)_{K) {L) 50%Storrslwal,cr Fee $ 3, '�SZ • �� 401/343.y0.00.03 ((�-) � (E))x (�)�(1.3 (M) 54% Roadway f�ce; S � {90• °� 000/343.20.00.00 i(U} 1 (�))x(�)=EM) 4. Check: Makc eure(J) +(K}+ (L)+(M)_(1} � M:IFILE.SYS�RMI9BBLDGCS10003.DOClbh Rer 3199 �— __ _ �ep�-06-02 06:06P Rice Fergus Miller 360 792 1385 P_ O1 FAXsheet R�c aq:�{IIC."URE � '"C F i14NY�NG %KJ MIL ER � AS REQUESTED ° � September b,200� � a TO: Tracy Coleman � tiry of Renton LL 1055 South Grady Way a Renton,WA 98055 � � � FROM: Bob Miller-Rhees — bmiller@rfmarch.com � 0 SU8IECT: Public Works Construction Permit Application - TOTAL PAGES: 3 " P MESSAGE: x � Tracy, _ Here are the completed forms.Still missing the tax 10#if that is important.Cost ' numbers are from 1ohn.Let me know if there is anything else needed for submittal_ ;, '� James wiEl ha�e the energy forms Monday. ^ � Slncerely, � 0 Rlce Fergus Miller '° /��,/�,:;�,,� %.�C�.�,. -�,. _ � Y f � � � Bob Mi11er-Rhees, m P Associate z o � u I = I _ � < � x 0 � x I W I� C m � � W C 1-- N Z If you did not receive all of the pages and/or attachments,or have received tfiis transmission in error,please contact Robin Murray o • in�rnediatety. .o J � � � ! � TECHNICAL INFORMATION REPORT , (Storm Drainage) FOR FIRE STATION #12 CITY OF RENTON WASHINGTON � , -� Prepared For: City of Renton Fire Department And Rice Fergus Miller Architecture & Planning Prepared: August 16, 2002 720 South 348th Street Tel(2531 838 6113 Tacoma 1253)927 0619 Civi( Engineering Land Planning I Federal Way. WA 98003 Fax (253)838 7104 Seattle (206)623 5911 Project Management Public Works � www.esmcivil.com Bremerton(3601 792 3375 Land Surveying I II� III TABLE OF CONTENTS I. Project Overview II. Preliminary Conditions Summary III. Off-Site Analysis IV. Retention/Detention Analysis and Design V. Conveyance Systems Analysis and Design VI. Special Reports and Studies VII. Basin and Community Planning Areas VIII. Other Permits IX. Erosion/Sedimentation Control Design X. Bond Quantities Worksheet XI. Maintenance and Operations Manual Figures • Figure 1 —TIR Worksheet • Figure 2 —Vicinity Map • Figure 3 - Downstream Analysis Summary Map • Figure 4 — Soils Map & Description (2 Pages) • Figure 5 — Hydrologic Soils Group Table , • Figure 6 — 2 Year King County Isopluvial Map j • Figure 7 — 10 Year King County Isopluvial Map I, • Figure 8 — 100 Year King County Isopluvial Map • Figure 9 — SCS Curve Numbers Table I • Figure 10 - Existing & Proposed Hydrology Basin StormShed I Calculations (2 Pages) • Figure 11 — Existing Basin Map • Figure 12 — Developed Basin Map • Figure 13 —25 Year Conveyance Calculation Worksheet • Figure 14 — 100 Year Conveyance Calculation Worksheet �i Renton Fire Station#12 T.I.R. August 16,2002 • - I SECTION I PROJECT OVERVIEW The project site is located on NE 12�h Street between Jefferson Ave NE and Kirkland Ave NE. The project site fronts onto all three streets. The project site was developed previously as a restaurant. The structure was recently removed, however the remainder of the site consists of a.c. pavement, curb, gutter, and sidewalks along with minimal areas of landscaping around the site perimeter. The site has an existing storm drain conveyance system which drains into the existing storm drain system in NE 12�' Street via two connections (10"0 and 6" f?� pipes). The portions of the site fronting onto the three streets (curb, gutter and sidewalk) presently drain into the street and the storm water is picked up in one of three catch basins located along NE 12th Street. The proposal is to re-develop the site with a fire station and associated parking areas. A new collection and conveyance system is proposed to connect into the two existing storm drain connections. Renton Fire Station#12 T.I.R. August 16,2002 Page 1 of 2 City� of Renton Development Services Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET PART 1 PROJECT O`VNER AND PART 2 PROJECT LOCATION PROJECT ENGI�\EER A�TD DESCRIPTION Project Owner Renton Fire Department Project Name Fire Station#12 Address 1055 So. Gradv Way�Renton,WA Locarion Phone (425)430-6623 To�vnship 23 North Project Engineer John S.Chadwell Range 5 East Company ESM Consultin�Engineers, LLC Section 4 Address Phone 720 South 348�'Street Federal Wav Project Size 1.2 AC (253) 838-6113 Upstream Drainage Basin Size 0 AC PART 3 TYPE OF PER�'�IIT APPLICATION PART 4 OTHER PERMITS L— Subdivision — DOFiG HPA � Shoreline Nianagement C Short Subdivision _ COE 404 � Rockery X Grading � DOE Dam Safety � Structural Vaults 0 Commercial — FEMA Floodplain � Other C Other '� COE Wetlands � HPA PART 5 SITE COMMUNITY AND DRAINAGE BASIN Community Renton Drainage Basin East Lake Washington PART 6 SITE CHAR�CTERISTICS L� River I_I Floodplain � Stream � Wetlands 0 Critical Stream Reach � Seeps/Springs 0 Depressions/Swales � High Groundwater Table 0 Lake � Groundwater Recharge 0 Steep Slopes � Other � Lakeside/Erosion Hazard PART 7 SOILS Soil Type Slopes Erosion Potential Erosive Velocities Arents Alderwood 0- 15% Moderate to Severe �Additional Sheets Attached i ; i � ', . � Page 2 of 2 City of Renton Development Services Division TECHNICAL INFORMATION REPORT (TIR) ��'ORKSHEET PART 8 DEVELOPMENT LIMITATIONS REFERENCE LIMITATION/SITE CONSTRAINT 0 Ch.4-Downstream Analysis None C' C C C � Additional Sheets Attached PART 9 ESC REQUIREMENTS MINI.vIU1v1 ESC REQL�IREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION DURING CONSTRUCTION X Sedimentation Faciliries X Stabilize Exposed Surface X Stabilized Construction Entrance X Remove and Restore Temporary ESC Facilities X Perimeter Runoff Control X Clean and Remove All Silt and Debris X Clearing and Grading Restrictions(By Dates) 0 Ensure Operation of Permanent Facilities X Cover Pracrices 0 Flag Limits of NGPES X Conshuction Sequence � Other �� Other PART 10 SURFACE WATER SYSTEM I Grass Lined Channel ' Tank '�J Infiltration Method of Analysis ' X Pipe System C Vault � Depression SBUH 0 Open Channel C Energy Dissapator � Flow Disperal Compensation/Mitigation 0 Dry Pond C Wetland � Waiver of Eliminates Site Storage � Wet Pond C Stream � Regional Detenrion Brief Descriprion of System Operarion Collection and conveyance pipe svstem connected to existin� Citv pipe svstem after passinQ throu�h oillwater separator. Facility Related Site Limitations Reference Facility L'unitations 0 Additional Sheets Attached PART 11 STRUCTURAL ANALYSIS PART 12 EASENIENTS/TRACTS Cast in Place Vault ' Other Drainage Easement '� Retaining Wall CI Access Easement '� Rockery>4'High C Native Growth Protection Easement 0 Structural on Steep Slope C Tract C Other Wetland PART 14 SIGNATURE OF PROFESSIONAL ENGINEER I or a civil engineer under my supervision have visited the site. Actual site condirions as observed were incorporated into this worksheet and the attachments. To the best of my knowledge the information provided here is accurate. Si nature/Date i:'�.esm-jobs\9961document\tirsheet-aug 02.doc � � �� r �� , #��t r� � � � s�� e � — �� .N ,,� �� ,��fi��r� E�v� w,,,� � � � � �"I -� � � . � �ir�cl�d �� . �#r�� . ,�,� � � �� . � � � � � � � � � �� - ' �' � � � �� +.+� r SECTION II PRELIMINARY CONDITIONS SUMMARY No specific Preliminary Approval Conditions were provided. However the site re- development must meet the applicable Core and Special Requirements of the 1999 King County Surface Water Design Manual. CORE AND SPECIAL REQUIREMENTS Core Requirement (1) — Discharge at a Natural Location The project site currently drains into an existing on-site storm drainage conveyance system which connects to the existing storm drain in NE 12�' Street. Existing sidewalks and drive approaches drain into the adjacent street gutters. ' The redevelopment of the site proposes to discharge at the same locations, utilizing existing storm drain laterals. Portions of the redeveloped site, including new sidewalks, will drain to the NE 12th Street, Jefferson Avenue NE and Kirkland Avenue NE street gutters. Core Requirement (2) — Off-site Analysis I Upstream - A small portion of ground to the north of the project site drains onto I the site. The area is minimally landscaped and it is included in the existing and proposed hydrologic calculations. Downstream — The hydrologic calculations for this proposal demonstrate that the site will not have any impact to downstream drainage systems, and proposes less than 5,000 s.f. of new impervious surface (defined as surfaces that increase the runoff curve number). As such a downstream analysis is not required. No impact to downstream drainage systems is demonstrated by the reduced peak flow rates shown in Section IV below. Core Requirement (3) — Runoff Control The project is exempt from On-site peak rate runoff control as the proposed project post-development peak rate runoff is less than the existing condition peak rate runoff for the 100 year 24 hour design storm. The project is also exempt from the bio-filtration requirement because the project does not propose 5,000 s.f. or more of new impervious surface subject to vehicular use. Core Requirement (4) — Conveyance System The proposed design uses 12-inch minimum storm drain lines, with 6-inch or 8- inch lines connecting roof drains to the main storm drain system. The proposed drainage system sizing was verified such that 0.5 feet of freeboard will exist during a 25-year storm event and that storm structures do not overtop during the 100-year event. In keeping with the proposed plans to have no drainage impacts to the existing storm drain conveyance lines in NE 12th Street, the existing 6-inch Renton Fire Station#12 T.I.R. August 16,2002 and 10-inch laterals were used to connect the proposed on-site storm drainage collection system to the existing storm drain. Core Requirement (5) — Temporary Erosion and Sedimentation Control A Temporary Erosion and Sedimentation Control plan has been prepared with the final construction drawing set. A combination of the following Best Management Practices will be utilized: defined clearing limits, cover measures, perimeter protection by filter fabric fence, rock construction entrance, sediment traps and or rock check dams in interceptor ditches, storm drain inlet protection, and TESC measures maintenance. Special Requirement (1) — Critical Drainage Areas The project is located within Aquifer Protection Zone 2. Additional requirements include: • Biofiltration Swale — Not required as project does not propose 5,000 s.f. of new impervious surface subject to vehicular use or storage of chemicals. • Lining of Drainage Ditches — Not applicable as project does not propose any surface drainage ditches or swales. • Wetpond — The project does not meet the threshold requirements for construction of a wetpond as the project will not construct more than one acre of new impervious surface and does not direct discharge to a receiving body of water or discharge to a type 1 or 3 stream or wetland. Special Requirement (2) — Compliance with Existing Master Drainage Plan Not applicable as project is not part of a Master Planned Development. Special Requirement (3) — Conditions Requiring a Master Drainage Plan Not applicable as the project does not meet the thresholds for requiring a Master Drainage Plan. Special Requirement (4) — Adopted Basin or Community Plans Not applicable as the project does not lie within an Adopted Basin or Community Plan. Special Requirement (5) — Special Water Quality Controls Not applicable as the project does not propose more than one acre of new impervious area subject to vehicular use or storage of chemicals. Special Requirement (6) — Coalescing Plate OiINYater Separators Not applicable as the project does not propose to construct more than 5 acres of impervious surface. Renton Fire Station#12 T.I.R. August 16, 2002 Speciai Requirement (7) — Closed Depressions Not applicable as the project does not drain into a closed depression. Special Requirement (8) — Use of Lakes, Wetlands or Closed Depressions for Runoff Control Not applicable as the project does not drain into a lake, wetland, or closed depression for runoff control. Special Requirement (9) — Delineation of 100 Year Floodplain Not applicable as the project does not contain or abut a stream, lake, wetland or closed depression. Special Requirement (10) — Flood Protection Facilities for Streams Not applicable as the project does not contain or abut a Class 1 or 2 stream. Special Requirement (11) — Geotechnical Analysis and Report Not applicable as the project does not propose to construct a pond or an infiltration system. Special Requirement (12) — Soil Analysis and Report Not applicable as the existing SCS soils maps are sufficient for determining the classification of the underlying soils. Renton Fire Station#12 T.I.R. August 16,2002 SECTION III OFF-SITE ANALYSIS As noted previously under "Core Requirment #2" a detailed Level 1 Off-site analysis is not required. This is based on the "no-impact" nature of the proposal, which includes a reduction in total impervious surface, a reduction in impervious surface subject to vehicular use, a reduction in vehicle trips (vs. pre-existing restaurant), and a reduction in peak storm flow rates. Though a detailed Level 1 Off-site analysis is not required, the following description is provided as additional information. The existing on-site storm drain collection system connects to the existing storm drain in NE 12th Street via a 10- inch and a 6-inch CMP lateral. For reasons of maintaining no impact to downstream storm drains, we are proposing to use the two existing laterals. The existing storm drain in NE 12`h Street is a 36-inch CMP. The 36-inch storm drain line continues west in NE 12�' Street at slopes varying from 0.32% to 7.6%. Approximately 1,550 feet downstream of the site, at Edmonds Ave NE the storm flows proceed south in the storm drain system. A map of the downstream analysis area is included as Figure 3. Beyond the '/4 mile downstream extent of the usual Level 1 downstream analysis, the storm line connects into a smaller (18") storm drain at Edmunds Ave NE, where the flow continues southerly in Edmunds. It is beyond the scope of this analysis to determine why the 36" drain connects into an 18" drain downstream, however it would appear that due to the considerably steeper grades in Edmunds, the change in pipe size may not act as a flow restriction. Renton Fire Station#12 T.I.R. August 16, 2002 SECTION III I OFF-SITE ANALYSIS As noted previously under °Core Requirment #2" a detailed Level 1 Off-site analysis is not required. This is based on the "no-impact" nature of the proposal, which includes a reduction in total impervious surface, a reduction in impervious surFace subject to vehicular use, a reduction in vehicle trips (vs. pre-existing restaurant), and a reduction in peak storm flow rates. Though a detailed Level 1 Off-site analysis is not required, the following description is provided as additional information. The existing on-site storm drain collection system connects to the existing storm drain in NE 12th Street via a 10- inch and a 6-inch CMP lateral. For reasons of maintaining no impact to downstream storm drains, we are proposing to use the two existing laterals. The existing storm drain in NE 12�' Street is a 36-inch CMP. The 36-inch storm drain line continues west in NE 12�h Street at slopes varying from 0.32% to 7.6%. Approximately 1,550 feet downstream of the site, at Edmonds Ave NE the storm flows proceed south in the storm drain system. A map of the downstream analysis area is included as Figure 3. Beyond the '/4 mile downstream extent of the usual Level 1 downstream analysis, the storm line connects into a smaller (18") storm drain at Edmunds Ave NE, where the flow continues southerly in Edmunds. It is beyond the scope of this analysis to determine why the 36" drain connects into an 18" drain downstream, however it would appear that due to the considerably steeper grades in Edmunds, the change in pipe size may not act as a flow restriction. Renton Fire Station#12 T.I.R. August 16,2002 !' " I l� `id �l!I/'�/II� M��I„y�li,�',-AL "'..�— :--�— \{�1!Pi � /\ --I ;" � 1 � // \ Fr----i "?Yal:t;;��w�v"",la�utiw `tt�,:�;yvro��,'rw� �� "..L�.....�-. � i I( i�� !�.� � % _ � '+.rN.�n ai 1. �r �� ' ��, . 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" � , � � i ...� � ` .. _...: �.. � 1 7 2 '', i ' i tr � / � � ,� � ��, �'� �`� ', �� .cz-. � �� ,•- � �.oz- :�� II'�a.cz'r. , �,��:� ,.� , � �,` � � '�' 17.02-� .D� ,�``�.orc� , i � , , ` � 1 � � ��` � i �` . ��' M I D2-I i I I�I I I �� ` 17.fl-1 ' �l � ��V.�� ,��,\; �� , , �� i I O:C2- i ,1 7.E2-16 1 I7. 2-10 7 E 6 � � -'�� '��;,�' �� ;�iy i��.�z-'� 1 1, , � �� ii � , .� � � � � � ��.ce; ��.ca�i � �� .N� �11 �� z � E5 • 9 T23N R5E W 1/2 �` ��Y O Q _2Q0 4P0 �� `n� + UTILITIES DIVISION �---- R°n�n �iry �.�i�, 1:4800 �� -� P/B/PW TECHNICAL 8ERVICE8 Coaeonr Incar..ls o.s or l.o aeeer. ��N.�o$ u�o3�� N�� ' 4 T23N R5E W 1/� SECTION IV RETENTION/DETENTION ANALYSIS and DESIGN Existing Site Hydrology The existing site conditions are based on the site's most recent use as a restaurant. The 1.3 acre basin area consists primarily of the previous building site and the parking lot. Only a small portion of the site, mostly around the perimeter has any landscaping. The site has an existing storm drain conveyance system consisting of six catch basins which drain into the existing storm drain system in NE 12th Street via two connections (10"0 and 6" Q� pipes). The portions of the site fronting onto the three streets (curb, gutter and sidewalk) presently drain into the street and the storm water is picked up in one of three catch basins located along NE 12tn Street. The project site drainage features were calculated from the back of walk, as the areas towards the street currently drain into the street, and will continue to do so under the proposed plan. The existing site coverage is summarized below: Cover T e Acrea e Percenta e Buildin s 0.227 Ac. 17.5% Pavement 0.803 Ac. 61.8% Landsca in 0.269 Ac. 20.7°/o Total 1.30 Ac. Soils The Soil Conservation Service (SCS) Maps indicate the presence of Alderwood Arents series soils throughout the project site (Figure 4). These soils are hydrologic soils group "C" according to the King Count Surface Water Design Manual (Figure 5). Rainfall The design rainfall was obtained from the isopluvial maps in the 1990 King County Surface Water Design Manual (Figures 6-8). The 2-year 24-hour design rainfall is 2.0 inches, the 10-year 24-hour design rainfall is 2.9 inches and the 100-year 24-hour is 3.89 inches. The six-month design storm is calculated as 0.67 inches. Renton Fire Station#12 T.I.R. August 16,2002 SCS Curve Numbers Table and the Existing & Proposed Hydrology Basin StormShed Calculations are attached as Figures 9 and 10. The existing storm flows are summarized below: 24 Hour Storm Peak Flow Rate Volume 2-Year 0.54 cfs 0.18 ac-ft 10-Year 0.82 cfs 0.27 ac-ft 100-Year 1.14 cfs 0.38 ac-ft Developed Site Hydrology The developed site hydrology is divided into three sub-basins. The easterly basin drains to the existing 6" concrete drain pipe near the southeast corner of the site. The westerly basin drains to the existing 10" concrete drain pipe near the southwest corner of the site. There is a small portion of the site which will drain directly into the street gutters along the frontage roads. The proposed project site plan, developed by Rice Fergus Miller, includes the new fire station building along with parking areas, drive approaches, new curb, gutter and sidewalk along the three road frontages, and landscaped area. This is a redevelopment project which proposes less than 5,000 s.f. of new impervious surface subject to vehicular use. In fact the project proposes less impervious surface than the previous use. For emphasis we note that the project proposes a site with 0.97 acres of impervious area, while the existing site has 1.03 acres of impervious area. The combined total of these three sub-basins are summarized below to emphasize the reduction in the amount of impervious surFace (9.3%) proposed by this project: Cover T e Acrea e Percenta e Buildin s 0.280 Ac. 21.5% Pavement 0.630 Ac. 48.5% Landsca in 0.390 Ac. 30.0% Total 1.30 Ac. The developed storm flows for each sub-basin are summarized below: East Basin 24 Hour Storm Peak Flow Rate Volume 6 Month 0.02 cfs 0.005 ac-ft 2-Year 0.06 cfs 0.02 ac-ft 10-Year 0.10 cfs 0.03 ac-ft 100-Year 0.13 cfs 0.04 ac-ft Renton Fire Station#12 T.I.R. August 16,2002 West Basin 24 Haur Storm Peak Flow Rate Volume 6 Month 0.07 cfs 0.026 ac-ft 2-Year 0.35 cfs 0.12 ac-ft 10-Year 0.56 cfs 0.18 ac-ft 100-Year 0.78 cfs 0.26 ac-ft Street Basin 24 Hour Storm Peak Flow Rate Volume 6 Month 0.03 cfs 0.009 ac-ft '! 2-Year 0.10 cfs 0.03 ac-ft ' 10-Year 0.15 cfs 0.05 ac-ft 100-Year 0.20 cfs 0.07 ac-ft Hydrologic Analysis The existing hydrology for the project site was analyzed using the "Santa Barbara Urban Hydrograph" (SBUH) utilizing the StormShed software package (Engenious Systems). Due to the nature of the site being a redevelopment site, which proposes a reduced amount of impervious area, no on-site detention will be required. A summa of the combined eak flow rates is summarized below: Storm Event Existin Peak Flow Rate Pro osed Peak Flow Rate Chan e 2-Year 0.54 c.f.s. 0.51 c.f.s. -.03 10-Year 0.82 c.f.s. 0.81 c.f.s. -.01 100-Year 1.14 c.f.s. 1.11 c.f.s. -.03 As noted previously for Core Requirement #3, the proposed project meets the criteria for exemption from On-Site Peak Rate Runoff Control. The Existing Basin Map and the Developed Basin Map are included as Figures 11 and 12. Renton Fire Station#12 T.I.R. August 16,2002 � ti ( _ \I.�; � y, . �,`34 �..:� `V r:0 A".��" pn� .,.1 rr� ti r Lr : �, . f� d...�s ,.rvR�r. ��. ' .f?"' . Y �+� /�� i '� cy ; �_rF1 � - a c'> . �� .e n,�7r �.:C�� s� �' F ��} �N j'��G ��.' !.. '*i f r 'I ��° 1 � ��r '��'t'4�`t �,a4�� 1 ��',Q '�t �� -�K� S'#j � ,� ,;r � :<'Iy€ ,.� �f`3N� � -}x 1� i''��J��..YAy:y tl �_)� i•. � ��1#�l �� Nv'I wJi �� r" . .�N( . ; � �.' 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Yrr '�` ' Kp��,� �� <a�' r .�j�. 4�3 �,��i ��,� ��h < �fF� ' �� ,,t`�P rTa:?� 4t iI� r^r�' �wtr= �: •.,� t d�i �f �,'t . y ` `-.w � �. + f t � 1 1��t ,i �' ,.� �, i �,')�, ,�'r� �,.1� ( ��. �1`1 f T lc :r I ,�fi 1 . �. ��. 7�� tfw '�,� � .`� `�i ;1 Se1:;F K �. }nry '� ; "'G �.;. G''�� C �r i. �,�' l+ `!�'$� ' ' O � �1 .t � �1 � „r t�za .� t .,:, 1 �i 1 �s 2 � , t ii c�C � r�i r 4 �� 4: t�, � Q'b O � � �.ti �-ti+��.1 r •7�� r ,j��'�+ , �� r f � �n +� a..� �°�,� �t 4��y'`a � t 'p., � r�'tMa�� ' .�+� �;• . a�",fi 1 'F�' � �� t ��.'�.�';25� ��- ri y' �� ilt—�M1i` .�\ T � 1 . ' iY�,,��.� r�f �} i 1 i�k w. ,�,1¢ '�' � .�i; � �� w'�F�� :'S i�i ac I �t'.r r� �t. �,�Y _ "!�� _ t ��L' ,f1.'�� + �.. ,� � � .� ,. , . _ . , ,� � , Q�.�; u�:i�,�.nct�;a.��c:�`�, .��'•�`;it,�-+�;...r�«,n.�,t�+��;.�,,�c.,.:��_3��n�sGti:a,.,�:?'�,�`rr.��ar, a,, � �4rents, Alderwood Material Some areas are up to 30 percent included soils � that are similar to this soil material, but either �' shallower or deeper over the compact substratum; �rents, Aldeiwood material consists of Alderwood t and some areas are 5 to 10 percent very gravelly i ls that have been so disturbed through urban- � Everett soils and sandy Indianola soils . �acion that they no longer can be classified with Runoff is medium, and the erosion hazard is he Aiderwood series. These soils, however, have � moderate to severe. � � similar features. The upper part of the soil, , ' This soil is used for urban development. Ca- c . depth of 20 to 40 inches, is brown to dark- pability unit IVe-2; woodland group 3d2. L�„+n gravelly sandy loam. Below this is a grayish- rown, consolidated and impervious substratum. Arents, Everett material (An) .--This is a level l �es generally range from 0 to 15 percent. to gently sloping, dark-brown gravelly or very �ese soils are used for urban develo ment. gravelly sandy loam. It is very similar to Everett P gravelly sandy loam (see Everett series) , but it has been disturbed and altered through urban de- rents, Alderwood material, 0 to 6 percent slopes velopment. Multicolored very gravelly coarse sand a ) .--In many areas this soil is level, as a is at a depth of 8 to 40 inches. Areas are common- .��lt of shaping during construction for urban ly rectangular in shape, and range from 1 to 120 icilities. Areas are rectangular in shape and acres in size. a e from 5 acres to about 400 acres in size. Representative profile of Arents, Everett mate- epresentative profile of Arents, Alderwood rial, in a homesite, 440 feet west and 100 feet i__rial, 0 to 6 percent slopes, in an urban area, nozth of the center of sec. 11, T. 24 N., R. 6 E.: ,300 feet west and 350 feet south of the northeast � �r of sec. 23, T. 25 N., R. 5 E. : 0 to 8 inches, dark-brown (7.5YR 3/4) gravelly sandy loam, brown (7.5YR 5/4) dry; massive; __ 26 inches, dark-brown (lOYR 4/3) gravelly soft, very friable, nonsticky, nonplastic; sandy loam, pale brown (lOYR 6/3) dry; few roots; 30 percent gravel content; massive; slightly hard, very friable, non- slightly acid; clear, smooth boundary. 8 to sticky, nonplastic; many roots; medium acid; 14 inches thick. abrupt, smooth boundary. 23 to 29 inches 8 to 60 inches, grayish-brown and light olive-brown thick. (2.5Y 5/2 and 5/4) very gravelly coarse � `� 60 inches, grayish-brown (2.5Y 5/2) weakly ` sand, light gray and light yellowish brown I consolidated to strongly consolidated glacial � (2.SY 7/2 and 6/4) dry; single grain; loose, till, light brownish gray (2.SY 6/2) dry; nonsticky, nonplastic; few roots; 55 percent common, medium, prominent mottles of yellowish gravel and 10 percent cobblestone content; brown (lOYR 5/6) moist; massive; no roots; medium acid. medium acid. Many feet thick. The upper part of the soil ranges from dark The upper, very friable part of the soil extends brown to olive brown and from gravelly sandy loam ^ depth of 20 to 40 inches and ranges from dark to very gravelly loamy sand. The substratum ranges � sh brown to dark yellowish brown. from black to olive b mwn. �me areas are up to 30 percent included soils This soil is somewhat excessively drained. The at are similar to this soil material, but either effective rooting depth is 60 inches or more. a"ower or deeper over the compact substratum; Permeability is rapid, and available water capacity d ome areas are 5 to 10 percent very gravelly is low. Runoff is slow, and the erosion hazard e tt soils and sandy Indianola soils. is slight. This .Arents, Alderwood soil is moderately well This soil is used for urban development. Ca- a�*+ed. Permeability in the upper, disturbed soil pability unit IVs-1; woodland group 3f3. t ial is moderately rapid to moderately slow, p ding on its compaction during construction. Beausite Series � substratum is very slowly permeable. Roots nP*rate to and tend to mat on the surface of the � lidated substratum. Some roots enter the The Beausite series is made up of well-drained � ratum through cracks. Water moves on top of soils that are underlain by sandstone at a depth � substratum in winter. Available water capacity of 20 to 40 inches. These soils formed in glacial ��W. Runoff is slow, and the erosion hazard is deposits. They are rolling to very steep. Slopes i :, are 6 to 75 percent. The vegetation is alder, fir, ' �s soil is used for urban development. Ca- cedar, and associated brush and shrubs. The annual �ility unit IVe-2; woodland group 3d2. precipitation is 40 to 60 inches, and the mean annual temperature is about 50° F. The frost-free season ranges from 160 to 190 days. Elevation is ? �nts, Alderwood material, 6 to 15 percent � 600 to 2,000 feet. �_ (AmC) .--This soil has convex slopes. Areas In a representative profile, the surface layer � rectangular in sllape and range from 10 acres to and the upper part of the subsoil are dark-brown �t 450 acres in size. KING COLTNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL (2) CN values can be area weighted when they appiy to pervious areas of similar CN's (within 20 ,� CN points). However, high CN areas should not be combined with low CN areas {unless the low CN areas are less than 15°� of the subbasi�l. In this case, separate hydrographs should be � generated and summed to form one hydrograph. FIGURE 3.5?A HYDROLOGIC SOIL GROUP OF THE SOILS IN KING COUNtY HYDRaLOGtC HYDROLaG(C SOIL C�nOUP GROUP' SOIL GROUP GROUP* Alderwood C Orcas Peat D � Arents, Alderw C Oridia D Arents, cverett �taterial B Ovall C Beausite C PlchucSc C . Bellingnam D Puget D 9riscot D PuyaUup B Buckley D Ragnar 8 Caastal3eaches Variable Renton D �arfnQnt Sitt Loam D Riverwash Variable �dgswick C Salal C =verett A B `Sammamisn D , Indianola A Seattle D I Kitsap C Shacar D I ' Klaus C Si Silt C , Mixad Atlwial l.and Varia�le Snohomish 0 �I Nelton A Sultan � C I N2wberg B Tukwila D � Vooksack C Urban Variable � Normal Sandy Loam D Woodinvilfe 0 HYDROLOGIC SQIL CaRCUP CIASSIFiCr1T(ONS A. (Low runoif pocential). Sols having high infiltration rates, even when thoroughly wetted, and consisting chieFly oi deep, well-to-�xcessively drained sands or gravels. Thesa soils have a high rate of water transmission. S. (Moderataly low n�noff potential�. Soils having moderate infiitration rates when thoroughly wetted; and consisting chier1y of moderately fine to moderately caarse teactures. These sols have a moderate rate of water transmission. C. {Moderately high runoff potentiai). So�7s having stow infltration rates when thoroughiy wetted, and consisting chiefly of soi7s with a layer that impedes dowrnvard movement of water, or sods with moderateiy fine to firse textures. These sods have a slow rate of water transmission. 0. (High runoff potential). Sods havinq very sfow infdtration rates when thoroughly wetted and consisting chietly of day sails with a high swelling potential, soils with a permanent hiqh water table. sods wich a hardpan oc c:ay layer ai or near the surface, and shaflow soils over nearly impervious maferial. These sods I have a very slow rate of water transmission. ' From SCS, TR-55, Second Edition. June 198&, Exhibit A-t. Revisions made from SCS. So�i Irtterpretation Record, Form #5, September t988. 1 ��. _ � 3.5.2_2 11rs2 KING COUNTY, WASHINGTON, S UR FACE WATER DESIGN .l�t ANUAL � FIGURE 3.5.1C Z-YEAR 24-HOUR ISOPLUVIALS - ��------�� —� -�, � �:_� �-�---- r -- — — -- .. �'� �'' �� J� ,' � ' -- __ � � ��— y� � �. � � — �� _ � � yp�' � r--� `:� � V � 'L—� � i _ � � � � `� } -`•— ; � 7.g+ = , � _ .�� 1 ••/ �f I1 � - � R4Yla1 I j � � �-IA � 1 _ , � • ; �_ j �•� ...r r � ♦ � y ' ; � ' ;'o -- r---� , r , � �i-` 9 fL,=.;..,, `� � � . ^� � , I � .� � � _ � _ ;. � - . . . ; � � ;�:�.• ,..,ti.:� � � � �.� _ ;��,� �^� � �� — `,;. � O� ; �: �'� '�� ,: _ �1i O .` ,_I� 1 r.�u�� N� 1� � 1 i � j �, , ,., y _ _"_ .N I � ` '�.�;.1 ��1`�._...�_� I ; ,� � � '— ' _ � .1 • 1/c - �� .f i �+^ 11�rtar�� ```1 1,�.`` � - .� �y= �1 I i� �a�ar�'•, ( G _ - � � .1,`��.� `I(JS iIt \i_i � •J \\ •� I t r 1( � - _� � � �.� �} � o, '"� -1� ��/ �� / � � 1 � :` .�� 'l� f ,i ....✓ i/ � � ( /� . � I \� �" T � '- �. �� A' ` �i ~ f — �`� � j �, 1 �'v I N ,� � � � ,� _ , � � � � _ lqq � %, ' a `T� 'na` j / ~ � `'~ -- _ 1\ ! y� '� �.' ,_ � U / � _ ; � 1 - = � \ ` 1 �n� � , + � .~� i 1 f ' ��`. �- � � � � - ' � I � �-a� �� ! ��;°�� / (' �+ � < � ��" I, a ' J� � t � \ f � � `�I `T' � j ,�'t� ��. ..�..+� �,i �j� ' ''Il 1 � `. � � � — j f/� )J r �. \�\ � � � , � /�'� �1 � �� -- `� `� � '' �. � ` 'i 'I S � ; . .i ;. - j /� _ ��'�� -- ,.�\ �' `� r I , ;•-- _`� .� � \ _ _ ,` } 1 N. _._._ry r '__ _ I ;. �! _�� l; '. _ -� � � �r� � _ �'"�,�� ; . , L �._ . N t,� � � , • _ '� 4' _ .�`1'_ '�` / l f u� �s — � ry. �r=:r --.�.�� — ,r , ; � .� � !'•� ' � _� . cY � i � \ _ 2-YEAR 24—HOUR PRECtPITATION �`�, � �•..,, � ,,3.4�" ISOPLUVIALS OF 2-YEAR 24HOUR �► - ' _ 35 TOTAL PRECIPITATION IN INCHES ' � ��1i '. _ ' ✓ � 0 1 2 3 � 3 6 7 8 Mlla � � � � ` � c�► ry `'1 ~' �,.; i:3oa,aoa 3.5.1-R L�� 1� KING COUNTY, WAS HINGTON, S URFACE WATER DESIGN MANUAL � �. FIGURE 3.S.lE 10-YEAR 24HOUR ISOPLUVIALS _ 2.1 --—�' — ,F,—�� -=� ---�- ---- --� ----- — —------ 22 `�'� � °�; „ � -- _ � � :!` � ; � �i�. � '� - � � � i '� �'= I ,y —� � 2S ;� � i , `` ' � — � ; � � 4� 2 / F �" ��.� ._ � � �� '� -6 �'! ,,,� _ oL �`. 2> �� ,�—a 1 a,�� — • ,/ �-� �� ° __ �j � � _-' ��1 � � �— � � �1 29 �� `` �` � ;j7�-r'�°= ��" u��,�"'�` — _ � _ '� � I � � � r. '""` J � I � � � ^�.: �� , _ j ,�!•I 1' ' 1 ,w,'' ' �I� — \� �" , '-"`� — ,�" I ' • - I •, .' � I " ' y f , ,- •��, ` � �I - •�r.. : �C'� w�.� �y '` 3� �'i ` : I � �1 Wrar.\ `� J � �• l � � y �� Ju ,, ,.`( � -1 .-� ISIaMi i `a�' �i —� T`✓— � r. • � � `i1i % � :� � � � � - � _1 �' ,� I '� � 32 ! __.� _ / // _`� j '.� �\ i — �, � J / I '1( � 'I� / � � 33 r/ � , � _ s,� ; �, � _ ' �� /� r' � \ �.y• `� � 7 � , � Y� f`� 1 i � / � t . _ � _ ' ! ��., .! l ` \ 2,94 --%�I ,i i . , . � ` .� �/ i -'- / �. �� i� � - y ; �'� ' 1� _�_ � s � --`�".`� � �� - _ i � _ , _ I� _ � -y � �.— _. C , � �i � y :�= ;: ��,/ � �(� — r ( ).. �. �1 � �� S"� `� �� / i/ , '� " � \ - ( ,. �` { i� f `�(' l t i a.r�.� I � 1 ( � \'\ �,� .�. •,c..( \'r 1 ` ~ — j \ ' , _' .� `� � ) ,� �,L, �� _ / l -, / � 1 j` ^ , - _ �' ' . � „ � \ � 1'�- -�_ . � l I� �' �� _, `r — � .\ ; � \ '1 r��_ � `�. � -- �a� ,.\ � .1. i4 _' . ` � _ t �= — =,- '� �u , ' , . i� � _ ,- . � `�, `` . - � _ � ,- � " 1, -� � '^'_' • ' � �._ ��L--�-------`�., — � 1 ,; � . , � ,�-, I ; a ' a t � - .- 10—YEAR 24—HOUR PREC�PITATION ' ' _ ' f o� ' � `°�-,�; � 3.4� ISOPLUVIALS OF 10-YEAR 24-fiOUR �' ~ � _ TOTAL PREC1PtTAT10N IN INCHES r�0 ' I 3'� 2� t — , � �� 0 1 2 3 4 5 6 7 8 ,Mllss � � r~ ' � 3- a � � , ,,. `3• c, —� . �,. - 4 n KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL F'IGURE 3.S.1H 100-YEriR 24-HOUR ISOPLWIALS p 3 p------ � - �-- -�----�- ------- -- - --------�----------- . . 3.r`� . � i '�� _� ��, , �3 � �. —�-- =, - `` 3.4 , � - � - `` 1 `� , " �3 il ' -� + 1 �._ � `� j� 1 , . � `� `?7S `3 '- � � .I � i`,'1, _�` , , �� " �� a � r �9'�' -- ;.r.,.,, �- + I � 40 ,�--__ - _ °�f \ r. . 4.r � �:� �� ;� �° _ 1 ^1� � _J � � i� — _- � � ' � � � 4� -u- _ _ � -_ � . � . � -� �� ` ��' ~'�` ' � �� \ _A - - ' ,��n. � � _ �.�. f- 4.3 �' � � �� `` � , � r � :� � . i _ i j �, ,, 3 s ;�� , `. � .� o 4.q ::� - ,., - -- '-+--, u � -� ;' .� � i �� .� � � ^`.�``l ,� ; � � �� .�J ` �:� �, Y i, 1+.... ��, �J` � - '� '� r� 1 � ,f e1 ..� r�`.� ,� )� -- !'� y ' 4.S ,�� .,` ,, _ �j�� ' �� ;� -:,� . ��, —' 1•` ''' - % �; �, I •� � � ,� =d �. _ � ' ' � l �� ' ` ) 6 `f �^ - J � �I ` '� � - _ � � ��j ; �, j�� ( � i � v hn`' �� _ � � � �-�� 1 � � N --, � �,� 3.$ ` �. � � � r, r ) �_ 1' �=1 1 � ,� l - � ' _ \ ` � r Q / P' �T � � i' � ' � __ � � � =•' `i ? I�1 ;�1 -- I :\ ' � ' � � — i L %r �� i �� T� .� t �,� t\•� �� \ 1t — _ . : _. ' I. : �f� ('� ,r' r �f i C"' '' �' ` .r `\ )fl� ` ,� �� I �� {�.� // - v � � 4 ' ra. ; _ ;:r� , r�` �� , ,.a `L �•' i '4 `�� - -�` � x — � � ;( ` l �' % �'` ' �=� �-- , `' � �� ; ! � � � , _ � 1'\ � � `'' � � i � ,� � ti 1 �,��'�J O.� 1�J � � �~ —, / `t� •i la , � . /� � � ,J �.� �� '� � �\,\ � �•r ,� n � .. , ` 'J �� `G--� �f Il ' � ."� \ i �� i7r- : 4..7 � _� : . �� r`f � ` � / 1 ' 0�' � �� ' ' � 0�' 3� o� �..��~� - �- ' )0-YEAR 24-HOUR PREC�PlTATION o ' ' -'••., 6�- �J.4----ISOPLUVIALS OF 100-YEAR 24HOUR � � p�� ry , — � 5','.J�r�"�`� TOTAL PRECIPITATION IN INCHES 0►• ' _ I 4`� p�_ ` „'�'"', 0 1 2 3 z 5 6 7 8 Mlln �� ,�—�! 3.5.1-13 r,,4 �.�� '` ' ,�,,. KING COUNTY, WASHINGTON, SURF � CE WATER DESIGN MANUAL TABLE 3.5?B SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS _ �� SCS WESTEAN WASHINGTON RUNOFF CURVE NUMBERS (Published by SCS in 1982) Fiunoff curve rtumbers for selected agricuitural, suburban and urban land use for Type tA rainfail distribution, 24-hour storm duration. CURVE NUMBERS BY � HYDROLOGIC SC�GROUP I.AND USE DESCRIr'TION A 8 �v o Cultivated land(�): winter conaition � 86 9t 94 95 Mountain open areas: low growing orusn and grasstancfs 74 82 89 92 Meadow or F:,asture: I 65 78 85 89 Wood or forest land: undisturbed or older second growth 42 6•t 76 d1 Woo� or forest IarC: young second growih or brush �� 72 �S � Orch2rd: with cover crap 81 88 92 94 � Open spaces, lawns, ;,arks, golf courses, cemetenes, landsc,aping. good condrion: grass cover on 75% or more of the area 68 80 O 90 fair condrtion: grass cover on 50� to 75°� of the area 77 85 � 92 ' Gravel rcaCs and parking lots 76 85 89 91 Oirt roads and parking lots ' 72 82 87 89 ,'� , impervious suraces, pavement, reofs, etc. 98 98 98 98 Open water bodies: lakes, wetlands, ponds, etc. I 100 100 0 tQ0 Single Famiiy Residencial (2) Dwelling Unit/Gross Acre � Impervious (3) t.0 DU/GA t5 Separate curve number t.5 DU/GA 20 shall be se{ecied ' 2.Q DU/GA 25 for pervious and 2.5 DU/GA 30 impervious portian 3.6 DU/GA 34 of the site or basin 3.5 DU/GA 38 a.0 DU/GA a2 a.5 DU/GA as 5.0 DU/GA 48 5.5 DU/G� 5a . 0.0 DU/GA 52 6.5 DU/GA �4 7.0 DU/GA So Planned unit developments. 96 impervious condominiums, apartments, must be computed commercia! business and industrial areas. (1) For a more decaiied descnption or agricultural land use curve numbers refer co Natlonal Engineering Handbook, Section a, Hydrology, Ctiapter 9, August 1972. (2) Assumes roof and driveway runoff is directed into street/storm system. (3) The remaining pervious areas (lawn) are considered to be in good condition for these curve numbers. � ' � 3.�.�-3 I1193 Existing Condition Event Summary: BasinlD Peak Q Peak T Peak Vol Area Method Raintype Event ------- (cfs) (hrs) (ac-ft) ac /Loss Existing Condition 0.54 8.00 0.1768 1.30 SBUH/SCS kc24hr 2 yr Existing Condition 0.82 8.00 0.2715 1.30 SBUH/SCS kc24hr 10 yr Existing Condition 1.14 8.00 0.3768 1.3Q SBUH/SCS kc24hr 100 yr Drainage Area: Existing Condition Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur: 24.00 hrs Intv: 10.00 min Area CN TC Pervious 0.2690 ac 90.00 0.17 hrs Impervious 1.0300 ac 98.00 0.17 hrs Total 1.2990 ac Supporting Data: Pervious CN Data: Landscaping 90.00 0.2690 ac Impervious CN Data: Buildings 98.00 0.2270 ac Pavment 98.00 0.8030 ac Pervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Fixed Assumes 10 min. 0.00 ft 0.00% 10.0000 10.00 min Impervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Fixed Assumes 10 minutes 0.00 ft 0.00% 10.0000 10.00 min Final Developed - East Event Summary: BasinlD Peak Q Peak T Peak Vol Area Method Raintype Event ------ (cfs) (hrs) (ac-ft) ac /Loss Final Dev.-East 0.06 8.00 0.0205 0.15 SBUH/SCS kc24hr 2 yr Final Dev.-East 0.10 8.�0 0.0314 0.15 SBUH/SCS kc24hr 10 yr Final Dev.-East 0.13 8.00 0.0436 0.15 SBUH/SCS kc24hr 100 yr Final Dev.-East 0.02 8.00 0.0051 0.15 SBUH/SCS kc24hr Other Drainage Area: Final Developed - East Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur: 24.00 hrs Intv: 10.00 min Area CN TC Pervious 0.0300 ac 90.00 0.17 hrs Impervious 0.1200 ac 98.00 0.17 hrs Total 0.1500 ac Supporting Data: Pervious CN Data: Landscaping 90.00 0.0300 ac Impervious CN Data: Buildings 98.00 0.1200 ac Pervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Fixed Assumes 10 min. 0.00 ft 0.00% 10.0000 10.00 min Impervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Fixed Assumes 10 minutes 0.00 ft 0.00% 10.0000 10.00 min Renton Fire Station #12 T.I.R. August 16,2002 Final Developed-West Event Summary: BasinlD Peak Q Peak T Peak Vol Area Method Raintype Event ------ (cfs) (hrs) (ac-ft) ac /Loss Final Dev.-West 0.35 8.00 0.1171 0.93 SBUH/SCS kc24hr 2 yr Final Dev.-West 0.56 8.00 0.1835 0.93 SBUH/SCS kc24hr 10 yr Final Dev.-West 0.78 8.00 0.2581 0.93 SBUH/SCS kc24hr 100 yr Final Dev.-West 0.07 8.00 0.0264 0.93 SBUH/SCS kc24hr Other Drainage Area: Finai Developed-West Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur: 24.00 hrs Intv: 10.00 min Area CN TC Pervious 0.3600 ac 90.00 0.17 hrs Impervious 0.5700 ac 98.00 0.17 hrs Total 0.9300 ac Supporting Data: Pervious CN Data: Landscaping 90.00 0.3600 ac Impervious CN Data: Buildings, pavement, walks, patios 98.00 0.5700 ac Pervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Fixed Assumes 10 min. 0.00 ft 0.00% 10.0000 10.00 min Impervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Fixed Assumes 10 minutes 0.00 ft 0.00% 10.0000 10.00 min Final Developed - Street Event Summary: BasinlD Peak Q Peak T Peak Vol Area Method Raintype Event ------- (cfs) (hrs) (ac-ft) ac /Loss Final Dev.-Street 0.10 8.00 0.0325 0.22 SBUH/SCS kc24hr 2 yr Final Dev.-Street 0.15 8.00 0.0489 0.22 SBUH/SCS kc24hr 10 yr Final Dev.-Street 0.20 8.Q0 0.0670 0.22 SBUH/SCS kc24hr 100 yr Final Dev.-Street 0.03 8.00 0.0087 0.22 SBUH/SCS kc24hr Other Drainage Area: Final Developed - Street Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur: 24.00 hrs Intv: 10.00 min Area CN TC Pervious 0.0000 ac 90.00 0.17 hrs Impervious 0.2200 ac 98.00 0.17 hrs Total 0.2200 ac Supporting Data: Impervious CN Data: Buildings, pavement, walks, patios 98.00 0.2200 ac Pervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Fixed Assumes 10 min. 0.00 ft 0.00% 10.0000 10.00 min Impervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Fixed Assumes 10 minutes 0.00 ft 0.00% 10.0000 10.00 min Renton Fire Station#12 T.I.R. 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BOTHELL (�PS)�15-6�� www.esmcivil.com BREMERTON (J60) 792-3375 �;��, E�g�neering �a�a S�.�aY,�v Land Pionning RENT�N FIRE STATION #12 Public Works I Projecl Monogemenl I Londscape Archilecture �oa NO. 986-001-007 DA7E: E-1]-01 DEVELOPED BASIN MAP ORAWN: GF SHEET 1 O� � SECTION V CONVEYANCE SYSTEMS ANALYSIS and DESIGN The proposed design uses 12-inch minimum storm drain lines, with 6-inch or 8- inch lines connecting roof drains to the main storm drain system. The proposed drainage system sizing was verified such that 0.5 feet of freeboard will exist during a 25-year storm event and that storm structures do not overtop during the 100-year event. In keeping with the proposed plans to have no drainage impacts to the existing storm drain conveyance lines in NE 12th Street, the existing 6-inch and 10-inch laterals were used to connect the proposed on-site storm drainage collection system to the existing storm drain. Copies of the analysis are attached as Figures 13 & 14. .s, �� .. i� Renton Fire Station #12 T.I.R. August 16, 2002 ' � - Pressure Conve ance Calculation Sheet - 25 Year Storm _ Y ' . Barrel Entr Entr Exit Outiet Inlet Appr. Bend Junc. . Pipe Outlet iniet Barrel Barrel Velocity TW Friction HGL Head Head Control Control Velocity Head Head HW Top Top Depth Pipe Segment Q Length Size "n" Elev Elev Area Velocity Head Elev Loss Elev Loss Loss Elev Elev Head Loss Loss Elev Pipe Grate of HGL � � CB to CB (cfs) (ft) (ft) Value (ft) (ft) (s .ft) (fps) (ft) (ft) (ft) (ft} (ft) (ft) (ft) {ft) (ft) (ft) (ft) (ft} (ft) (ft) (ft) Ex. 36" CB #1 0.67 40 0.83 0.013 346.65 348 0.545 1228 0.02 348.36 0.10 348.46 0.00 0.02 348.49 348.51 0.011 0 0 348.50 348.83 355.78 7.28 CB#1 CB #2 0.67 59 1 0.013 348 349.53 0.785 0.853 0.01 348.50 0.05 348.56 0.00 0.01 348.57 0.011 0.01 0 348.57 350.53 355.65 7.08 ' � : CB#2 CB#3 0.67 94 1 0.013 349.53 349.99 0.785 0.853 0.01 348.57 0.09 348.65 0.00 0.01 348.67 0.011 0 0 348.66 350.99 354.99 6.33 CB#3 CB#4 0.67 53 1 0.013 349.99 350.24 0.785 0.853 0.01 348.66 0.05 348.71 0.00 0.01 348.72 0.011 0.02 0 348.72 35124 355.18 6.46 CB#4 CB#5 0.67 114 1 0.013 350.24 350.8 0.785 0.853 0.01 348.72 0.11 348.83 0.00 0.01 348.84 0.000 0 0 348.84 351.80 353.80 4.96 ' . Ex. 36" CB#8 0.11 40 0.5 0.013 348.12 349.9�. 0.196 0.560 0.00 350.07 0.04 350.11 0.00 0.00 350.12 350.14 0.000 0 0 350.12 350.41 355.32 5.20 fCB#8 CB#7 0.11 91 1 0.013 349.91 351.84 0.785 0.140 0.00 350.12 0.00 350.12 0.00 0.00 350.12 0.000 0 0 350.12 352.84 355.84 5.72 1 � Assumed full basin flow in each run � �TW-Assumed as dc in existing pipe to NE 12th Street � ' 1 I ' Renton Fire Station #12 -T.I.R. 16-Aug-02 I ' f . . �, ,.: . �: > :. ' . .., , - � ; ' �_ � ' ' _ SECTION VI SPECIAL REPORTS and STUDIES Geotechnical Evaluation Report — Zipper Zeman Associates, Inc., dated November 1, 2001. ; : �y' i-T i '. � , � ; �- ; � ; ' I I4 , �,� � , i �� i `, � , 1 _ � ', . , � Renton Fire Station#12 T.I.R. August 16,2002 Zipper Zeman Associates, Inc. Geotechnical and Environmental Consulting J-1177 November 1, 2001 City of Renton Renton City Hall—5`�Floor .Renton, Washington 98055 . Attention: Ms. Tracy Coleman Capital Project Coordinator Subject: Report of Geotechnical Services Proposed Fire Station 1209 Kirkland Avenue NE Renton, Washington Dear Ms. Coleman, Zipper Zeman Associates, Inc. (ZZA) has completed a geotechnical 'evaluation for the proposed Fire Station at 1209 Kirkland Avenue NE in Renton, Washington. This report presents the results of our geotechnical evaluation relative to design and general construction considerations. Authorization to proceed with this evaluation was provided through the contract agreement between the City of Renton and Zipper Zeman Associates, Inc. dated September 21, ' 2001. The field evaluation was completed on October 1,2001. We understand that the project is in the early planning stages, with the fire station ' building currently planned to be located in the central or southern portion of the property. The fire station will consist of a one to two story structure, with a possible basement. Portland concrete and asphalt concrete pavements are anticipated around the station for fire truck and � emergency vehicle access, and for general parking areas. i The purpose of our geotechnical evaluation is to assess subsurface conditions relative to the design and construction of the fire station. The scope of our services included an exploration program consisting of excavating seven test pit explorations at the site. Based on the subsurface conditions observed in the test pits, we performed geotechnical analyses and formulated recommendations that are presented in this report. Specific items addressed in this report include: 1. Description of the project site with exploratory locations shown on a site plan; 2. General subsurface conditions; 3. Earthwork and site preparation recommendations; 18905—33"d Avenue W.,Suite 1 l7 Lynnwood,Washington 98036 (425)77l-3304 � Proposed Fire Station J-1177 � Renton, Washington November l,2001 , Page 2 � 4. Structural fill and the suitability of on-site soils for use as structural fill; 5. Recommendations relative to the construction of' shallow spread footing � foundations and slab-on-grade floors; , 6. Recommended lateral earth pressures for subgrade (basement) walls and retaining , walls; 7. Preparation of pavement subgrades; 8. Wet weather construction considerations; . 9. Erosion control and site drainage considerations; 10. General seismicity and liquefaction potential; 11. Implications of elevator shaft installation; 3 12. Recommendations for further study, if appropriate. � SITE DESCRIPTION The proposed fire station site is located on the north side of NE 12`� Street, between Jefferson Avenue and Kirkland Avenue NE. The site consists of 6 lots encompassing � approximately 1.22 acres. The site slopes down to the south with an estimated relief on the order of 10 feet. Most of the property is covered with asphalt. A portion of the ground surface in the south-central area is dirt covered where a previous structure has been removed from the property. FIELD EXPLORATION The subsurface exploration program conducted for this study consisted of completing seven test pit explorations at the site on October 1, 2001. The approximate locations of the test _ pits are presented in Figure 1, Site and Exploration Plan. 'I'he test pit explorations were completed to depths ranging from 12 to 15 feet below the existing ground surface. Logs of the test pits aze enclosed with this report. Subsurface Conditions . In general, subsurface conditions in the test pits were fairly consistent. Test pits TP-1 through TP-b were located in areas covered with asphalt. Test pit TP-7 was located in the western portion of the removed structure. The asphalt and underlying base course (fill), where , I - present, extended to depths ranging from approximately 0.2 to 0.5 feet. Other fill consisting of �, loose to dense sand with variable silt and gravel was observed in test pits TP-1, TP-5, TP-6, and , I Zi�per Zeman Associates, Inc. 18905—33"Avenue W.,Suite l 17 Lynnwood,Washington 98036 (425)771-3304 Proposed Fire Station J-1177 ' � Renton, Washington November 1,2001 Page 3 TP-7. Some concrete debris and boulders were observed in the fill in test pit TP-6. The fill extended to depths ranging between 1 foot and 2 feet in these test pits. Native glacial till consisting of dense to very dense silty sand with gravel was observed below the asphalt in test pit TP-4, located in the northwest portion of the site, which is higher in elevation than the rest of the site. The glacial till extended to a depth of approximately 5 feet. Below the asphalt, fill, and native glacial till was native sand with minor to some silt and , variable gravel. The gravel content generally increased with depth where observed. These sands f typically were in a medium dense to dense condition and extended to the bottom of the test pits. I , Soil descriptions presented in this report are based on the subsurface conditions observed at the specific test pit locations. Variations in subsurface conditions may exist between the exploration locations, and the nature and extent of variations between the explorations may not become evident until construction. If variations then appear, it may be necessary to reevaluate the recommendations presented in this report. Groundwater � No groundwater or seepage zones were observed in the test pits at the time of excavation. It should be noted that groundwater conditions and soil moisture contents are expected to vary with changes in season,precipitation, site utilization, and other on- and off-site factors. Zones of ' � perched water may tend to develop above the relatively impermeable glacial till and silty zones within the native sand during periods of wet weather. ' CONCLUSIONS AND RECOMMENDATIONS Based on the subsurface exploration program, the project appears feasible utilizing � conventional shallow foundation support. The following recommendations have been prepared for the design and construction of conventional spread footing foundations and concrete slab-on- grade floors. Site Preparation We anticipate that cuts on the order of 10 feet will be required to establish the finish floor elevation for the planned basement. Site prepararion should include the removal of asphalt, _ existing fill, and organic soils, if encountered, and any other deleterious debris from building and paving azeas, or those locations where "structural fill" is to be placed. Exposed soils following site preparation should consist of the native medium dense to dense sand or the dense to very . dense glacial till. Any excavations that extend below finish grades should be backfilled with structural fill as outlined subsequently in this report. = Preparation for site grading and construction should include procedures intended to drain � ponded water and control surface water runoff. It may not be possible to successfully utilize on- Zipper Zeman Associates, Inc. , 18905—33b Avrnue W.,Suite 1 l7 Lynnwood,W�shington 98036 (425)771-3304 Proposed Fire Station J-I 177 Renton, Washington November 1, 2001 Page 4 site soils as "structural fill" if accumulated water is not drained prior to grading, or if drainage is not controlled during construction. Attempting to grade the site without adequate drainage control measures will reduce the amount of on-site soil effectively available for use, increase the amount of select import fill materials required, and ultimately increase the cost of the earthwork - and foundation construction phases of the project. After removal of pavement, existing fill and other deleterious material, and prior to . placement of structural fill, we recommend that foundation and floor subgrade areas, pavement areas, and areas to receive structural fill be proofrolled and compacted to a firm and unyielding _ condition in order to achieve a minimum compaction level of 92 percent of the modified Proctor maximum dry density as determined by the ASTM:D-1557 test procedure. Proofrolling should be accomplished with a heavy compactor, loaded double-axle dump truck, or other heavy _, equipment under the observation of a representative from our firm. The need for or advisability of proofrolling due to soil moisture conditions should be determined at the time of construction. We recommend that a representative from our firm observe the soil conditions prior to and � during proofrolling to evaluate the suitability of stripped subgrades. Excavated site soils may not be suitable for use as structural fill depending on the 3 moisture content and weather conditions at the time of construction. If soils are stockpiled for future reuse and wet weather is anticipated, the stockpile should be pro'tected with plastic sheeting that is securely anchored. If on-site soils become unusable, it may become necessary to = import clean, granular soils to complete wet weather site work. Subgrade soils that become disturbed due to elevated moisture conditions should be � overexcavated to expose firm, non-yielding, non-organic soils and backfilled with compacted structural fill. We recommend that the earthwork portion of this project be completed during extended periods of dry weather, if possible. If earthwork is completed during the wet season, it ' may be necessary to take extra precautionary measures to protect subgrade soils. Wet season earthwork may require additional mitigative measures beyond that which would be expected during the drier summer and fall months. This could include diversion of surface runoff around J exposed soils, draining of ponded water on the site, and collection and rerouting of groundwater seepage from upgradient on- and off-site sources. Once subgrades are established, it may be necessary to protect the exposed subgrade soils from construction traffic. Placing quany spalls, crushed recycled concrete, or clean pit-run sand and gravel over these areas would help protect the soils from construction traffic. Structural Fill IAll fill material placed in building, pavement, and non-landscaped areas should be placed as structural fill. Prior to placement, the exposed subgrade surfaces to receive structural fill � should be prepared as previously described. All structural fill should be free of organic material, _ debris, or other deleterious material. Individual particle size should be less than 3 inches in a ':; maximum dimension. I � Zipper Zeman Associates,Inc. 18905—33rd Avenue W.,Suite 117 Lynnwood,Washington 98036 (425)771-3304 Proposed Fire Station J-1177 Renton,Washington November 1,2001 Page 5 Structural fill should be placed in lifts no greater than 8 inches in loose thickness. The structural fill should be compacted to at least 95 percent of the modified Proctor maximum dry density as determined by the ASTM:D-1557 test procedure in building areas and to a depth of 2 feet below the subgrade surface in pavement areas. Below a depth of 2 feet in pavement areas, the structural fill should be compacted to at least 90 percent of ASTM:D-1557. In the case of roadway and utility trench filling, the backfill should be placed and compacted in accordance with current local codes and standards. The suitability of soils for use as structural fill use depends primarily on the gradation and moisture content of the soil when it is placed. As the amount of fines (that soil fraction passing the U.S. No. 200 sieve) increases, soil becomes increasingly sensitive to small changes in moisture content and adequate compaction becomes more difficult, or impossible, to achieve. Generally, soils containing more than about 10 percent fines by weight (based on that soil fraction passing the U.S. No. 4 sieve) cannot be compacted to a firm, non-yielding condition when the moisture content is more than a few percent from optimum. The optimum moisture content is that which yields the greatest soil density under a given compactive effort. - The native sand observed in the test pits generally appears suitable for use as structural fill. However, the glacial till observed in test pit TP-4 (to a depth of approximately 5 feet), anc the native silty sands (in the upper 1 to 2.5 feet in test pits TP-1, TP-2, and TP-6) contain �: significant fine-grained fraction. Consequently, use of these soils as structural fill will require that strict control of moisture content be maintained during the grading process. Soil moisture conditions should be expected to change throughout the year. Drying of over-optimum moisturc soils may be achieved by scarifying or windrowing su�cial materials during extended periods of dry weather. Soils which are dry of optimurn may be moistened through the application of water and thorough blending to facilitate a uniform moisture distribution in the soil prior to " compaction. In the event that inclement weather or wet site conditions prevent the use of on-site soil or non-select material as structural fill, we recommend that a "clean", free-draining pit-run sand and gravel be used. Such materials should generally contain less than 5 percent fines, based on that soil fraction passing the U.S. No. 4 sieve, and not contain discrete particles greater than 3 inches in maximum dimension. It should be noted that the placement of structural fill is, in many cases, weather-dependent. Delays due to inclement weather are common, even when using select granular fill. We recommend that site grading and earthwork be scheduled for the drier ' months, if at all possible. IPermanent Fill Slopes � � Permanent fill slopes should be constructed no steeper than 2H:1 V. If the slopes are . exposed to prolonged rainfall before vegetation becomes established, the surficial soils will be prone to erosion and possible shallow sloughing. Surficial repairs, such as protecring affected [ � Zipper Zeman Associates, Inc. 13905—33'"Avenue W.,Suite 1 l l Lynnwood,Washington 98036 (425)771-3304 Proposed Fire Station J-1177 Renton, Washington November l, 2001 Page 6 areas with quarry spalls, jute matting or other system, may be necessary until vegetation is established. Temporary and Permanent Cut Slopes Temporary slope stability is a function of many factors, including the following: l. The presence and abundance of groundwater; 2. The type and density of the various soil strata; _ 3. The depth of cut; 4. Surcharge loadings adjacent to the excavation; 5. The length of time the excavation remains open. � It is exceedingly difficult under the variable circumstances to pre-establish a safe and "maintenance-&ee" temporary cut slope angle. Therefore, it should be the responsibility of the contractor to maintain safe slope configurations since the contractor is continuously at the job site, able to observe the nature and condition of the cut slopes, and able to monitor the subsurface materials and groundwater conditions encountered. It may be necessary to drape temporary cut slopes with plastic or to otherwise protect the slopes from the elements in. order to minimize sloughing and erosion. We do not recommend unsupported vertical cuts deeper than 4 feet if worker access is necessary. The cuts should be adequately sloped or supported to prevent injury to personnel from local sloughing and spalling. The excavation should conform to applicable Federal, State, and local regulations. For preliminary planning purposes only, temporary cuts in the fill and upper 3 to 4 feet of � native sand will likely require slopes of 2H:1 V or flatter to reduce the potential for sloughing. The medium dense to dense sand observed at depth in the test pits is anticipated to maintain cut slopes on the order of 1H:1V. For all cut slopes, if seepage or surface iunoff occurs and is not controlled, flatter temporary slopes may be necessary. These guidelines assume that surface loads, such as equipment loads and storage loads, will be kept a sufficient distance away from the top of the cut so that the stability of the excavarion is not affected. � For medium dense to very dense native soils, or compacted structural fill, we generally recommend all permanent cut slopes be designed at a 2H:1 V inclination or flatter. It has been � our experience that permanent slopes steeper than 2H:1 V will tend to ravel and slough to a flatter inclination over time. In addition, with the steeper slopes, topsoil erodes readily and it is more difficult and takes longer to establish vegetation for slope protection. � Foundations � All footings should be founded on the medium dense to dense native sand, glacial till, or - on compacted structural fill that extends down to these competent native soils. Footings should not be founded on or within loose or disturbed narive soil or fill unless it has been evaluated and t C Zipper Zeman Associates, Inc. l8905—33"�Avenue W.,Suite 1 l7 Lynn�•ood,Washington 98036 (425)771-3304 1 Proposed Fire Station J-1177 I Renton, Washington November 1, 2001 Page 7 approved by the geotechnical engineer. Continuous or column footings may be designed for a maximum allowable bearing pressure of 3,000 psf. A one-third increase in this bearing pressure � may be used for short-term wind or seismic loading. Exterior footings should extend at least 18 inches below adjacent grade for frost�protection, while interior footings should extend at least 12 inches below adjacent grade. We recommend that all continuous and isolated footings be at least 18 and 24 inches in width, respectively. We estimate that the total settlement of foundation members founded within the medium � dense to dense sand, glacial till, or structural fill prepared as described above may approach 1 inch. Differential settlement of foundations founded within the same soil type couid approach '/z inch over a distance of 30 feet. Settlements would occur elastically as the loads are applied. i � � Foundation settlement is oftentimes a function of the condition of the footing excavation subgrade. Under no circumstances should footings be cast atop loose or soft soil, slough, debris, or surfaces with standing water. We recommend that a representative from our firm observe the condition of the footing subgrades prior to pouring footing concrete in order to confirm that the bearing soils are undisturbed and that conditions are consistent with the recommendations contained within this report. We recommend that perimeter footing drains with cleanouts be installed around the planned building. The drains should consist of a minimum 4-inch diameter perforated pip� embedded in at least a 24-inch wide envelope of clean, free-draining granular material containin, less than 5 percent fines (material passing the U.S. No. 200 sieve). Footing drains should b� directed toward appropriate storm water drainage facilities and not onto adjacent slopes. Roo� drains should not be connected to the footing drains. We recommend that the ground surfac� adjacent to foundations be sloped to drain surface runoff away from the structure. Slab-On-Grade Floors Slab-on-grade floor subgrades should be prepared in accordance with the site prepazation recommendations presented above. All slab-on-grade floors should be founded on the medium i dense to dense native sand, glacial till, or on compacted structural fill extending down to these ! competent native soils. Slab-on-grade floors should not be founded on or within loose or disturbed native or fill soil unless it has been evaluated and approved by the geotechnical engineer. We recommend that at least 4-inches of clean coarse sand and gravel (containing less than 5 percent material passing the U.S. No. 200 sieve) be placed between the prepared subgrade and bottom of the concrete floors. This zone will serve for support, and as a capillary break and working surface. In floor slab areas where moisture sensitive floor coverings are planned, an impermeable membrane (e.g. polyethylene sheet) should be placed directly beneath the floor slab to act as a vapor bamer. The impermeable membrane should be protected by two inches of fine, moist sand placed both above and below the membrane. The sand cover will provide protection for the Zipper Zeman Associates, Inc. 18905—33nd Avenue W.,Suite 117 Lynnwood,Washington 98036 (425)771-3304 Proposed Fire Station J-1177 Renton, Washington November l, 2001 Page 8 membrane and will promote uniform curing of the concrete slab. The sand cover should be moistened and tamped prior to slab placement. For basement and other below grade floors, we recommend that an underslab drainage system be installed below the new floor slabs. The underslab drainage system should consist of at least 12 inches of structural fill consisting of free-draining (less than 3 percent fines) coarse sand and gravel. To discharge water which tends to collect in the zone of structural fill, we ' recommend that a system of 4-inch diameter perforated drainage pipe be installed in trenches which extend below the zone of free-draining structural fill. These trenches should be at least 12 inches deep and backfilled with the free-draining coarse sand and gravel. The perforated drainpipe should have a maximum center-to-center spacing of 25 feet and should�be sloped to drain to a suitable discharge. Cleanouts should be provided for the perforated drainpipe. Backfilled Walls/Lateral Earth Pressures All backfill placed behind retaining or basement walls should be placed as structural fill compacted to a minimum of 92 percent of the maximtun dry density per ASTM D-1557. The compactive effort should be increased to 95 percent where settlement sensitive facilities are - supported on the wall backfll. To minimize lateral earth pressures and preyent the buildup of hydrostatic pressures, the bacicfill within 24 inches of the wall should contain less than 5 percent � fines, based on that portion passing the U.S. No. 4 sieve, coupled with a perforated pipe drain placed at the base of the wall backfill, similar in configuration to that described for the perimeter footings. The upper 1-foot of the wall bac�ll should consist of low permeability silty soil and _ the ground surface should be sloped away from the wall in order to reduce the potential fcr surface water infiltration behind the wal; _ � T�le fO110W1I1g I'CCOIriIrieIIdBd laiclai caiili �ii�a�ui:;�, �iiC�ci;I�u a� c�ui��aiclii iiu;u , densities, are based on the assumption of a relatively level backfill (slopes of 4H:1 V, or flatter) with no buildup of hydrostatic pressure behind the wall. If the backfilled walls are structurally _ restrained from lateral movement at the top, we recommend that they be designed for an"at-rest" equivalent fluid density of 55 pounds per cubic foot (pc�. If the top of the wail is free to move laterally in an amount equal to at least 0.1 percent of the wall height, they may be designed for !I - an "active" equivalent fluid density of 35 pcf. For building and retaining wall foundations, we j recommend using an allowable base friction value of 0.35. Passive resistance for foundations embedded at least 18 inches below finish grades may be computed using an allowable equivalent - fluid density of 250 pcf. ISurcharges due to sloping ground, adjacent footings, vehicles, construction equipment, etc., must be added to these values. The above equivalent fluid pressures assume that the backfill behind the walls is level and compacted to approximately 92 percent of the modified IProctor(ASTM D-1557} maximum dry density. Additional compaction adjacent to the wall will increase the earth pressure, while a lesser degree of compaction could result in post construction � settlements. � I Zipper Zeman Associates, Inc. 18905—33n°Avenue W.,Suite 117 Lynnwood,Washington 98036 (425)77I-3304 Proposed Fire Station J-1177 Renton,Washington November 1,2001 ; � Page 9 � I Utility trenches may act as groundwater conduits by intercepting perched groundwater I seepage. Some of these utility trenches may lead to the proposed building. Therefore, it is �, highly recommended that the wall backfill consist of free-draining aggregate as recomrnended i above. Additionally, footing drains should be constructed at elevations below all wall � penetrations and preferably at footing elevations. These drains should be connected to an � approved storm water discharge receptor. Seismic Criteria Figure 16-J in the 1997 Uniform Building Code classifies the subject site as being within Seismic Zone 3. Based on the subsurface conditions encountered at the site and published geologic literature, it is our opinion that Soil Profile Type S� should be used to describe the , average soil properties within the upper 100 feet beneath the site. This designation describes j soils that are considered very dense with a sheaz wave velocity of 1,200 to 2,500 feet per second, I - Standard Penetration Test values greater than 50, and an undrained shear strength greater than 2,000 psf. - Soil liquefaction is a condition where loose, saturated granular soils lo,ose strength during the ground shaking associated with an earthquake. No groundwater was encountered at the site ' to the bottom of the test pit excavations. In addition, the soils encountered in our test pits �� typically consisted of glacial till or medium dense to dense sand. The risk of liquefaction at the site is considered low due to the lack of groundwater and the overall condition of the native soils. � Erosion Control Erosion and sedimentation controls are recommended during construction to reduce the potential impacts to adjacent areas. Erosion control measures should be designed to prevent I sediment transport. This may be accomplished by constructing water bars or utilizing other methods to control surface water runoff, and constructing silt fences to control sedimentation. If construction is accomplished during the winter months, we further recommend that temporary � erosion protection be provided consisting of covering exposed soil areas with plasric sheeting, jute matting, and/or straw. We recommend that all bare soil areas be planted or mulched as soon as possible. It may be necessary to provide temporary erosion protection until vegetation has been reestablished. Pavements The native medium dense to dense sand and glacial till are considered suitable for subgrade support of pavements. We recommend that the subgrade in pavement areas be '' prepared as recommended in the Site Preparation section of this report. The upper one-foot of - pavement subgrade soils should be compacted to at least 95 percent of the maximum dry density Zipper Zeman Associates, Inc. 18905—33nd Avenue W.,Suite l 17 Lynnwood,Washington 98036 (425)771-3304 � Proposed Fire Station J-1177 Renton, Washington November 1, 2001 Page 10 determined in accordance with the ASTM D-1557 test method. The extent of any soil improvement or replacement can only be determined at the time of construction. Finished ' subgrade surfaces should be constructed to facilitate drainage and prevent ponding of water below the pavement section. We recommend that a layer of crushed base course be placed between the prepared subgrade or structural fill, and the pavement working surface material (asphalt or concrete). Base course material under Portland concrete and asphalt pavement should conform to Specification 9-03.9(3) of the WSDOT/APWA 2000 Standard Specifications, or current City of Renton or King County standards. Base material should be moisture conditioned and compacted to a minimum of 95 percent of the maxunum dry density per AST:�I D-1557. Other Considerations � We understand that an elevator for the new fire station facility may be considered. The elevator shaft may extend below the depth explored in our test pits. It is unknown if . groundwater nught be encountered within the limits of the elevator shaft. We recommend that the installation of the elevator shaft be monitored by a representative from our firm to assess if any special measures are necessary to deal with groundwater encountered in the drilled elevator - shaft hole. We understand that on-site stormwater disposal systems may be considered at the site. In � - general, the lack of a permanent shallow groundwater table, and the granular nature of the native soils observed in the test pits appear to suggest that some on-site infiltration may be feasible. However, we recotrunend that required soil infiltration testing per City of Renton and/or Kin`T � County Stormwater standards be performed to assess appropriate infiltration rates used in the design of on-site stormwater disposal systems. We recommend that any additional subsurface testing be performed in the immediate area of the planned infiltration system(s). CLOSURE This report has been prepared in accordance with generally accepted geotechnical engineering practices for the exclusive use of the City of Renton for specific application to the planned fire station at 1209 Kirkland Avenue NE in Renton, Washington. The conclusions and recommendations presented in this report are based on the explorations accomplished for this study. The number, location, and depth of the explorations were completed within the site and scope constraints of the project so as to yield the information necessary to formulate our recommendations. The plans for this project were in the preliminary stage at the time this report was written. Under the circumstances, it is recommended that we be provided the opportunity for general review of the. project plans and specifications in order to confirm that the recommendations and design considerations presented in this report have been properly ; interpreted and implemented into the project design package. Zipper Zeman Associates, Inc. 18905—33nd Avenue W.,Suite l 17 Lynnwood,Washington 98036 (425)771-3304 Proposed Fire Station J-1177 Renton, Washington November 1,2001 Page 11 The integrity and performance of foundation systems depend greatly on proper site preparation and construction procedures. Field judgement by a qualified engineer will be , necessary in order to determine the adequacy of the site drainage and foundation support � systems. Therefore, because of our familiarity with the site soils, we recommend that Zipper Zeman Associates, Inc. be retained to provide geotechnical engineering services during earthwork and foundation construction of the fire station. If variations in the subsurface conditions are observed at the time of construction, we would be able to provide additional . geotechnical engineering recommendations to the contractor and owner in a timely manner as the , project construction progresses. We appreciate this opportunity to be of service to you, and would be pleased to discuss the contents of this report or other aspects of the project with you at�your convenience. Respectfully submitted, Zipper Zeman Associates, Inc. $ T No� �/!=� �54, o� tiv�s��.y,atr � �'� , �� bf' ,� c�'�Z. Timothy H. Roberts, P.E., P.G. `-��, Project Engineer r 19409 �4' ��,� RFccsTe�``� `�w `ssf ONAL E�G k,,.n,--� a S EXPnaES 4/3/2002 James B. Thompson, P.E. Principal Enclosures: Figure 1 —Site and Exploration Plan Test Pit Logs (TP-1 through TP-7) I I I � Zipper Zeman Associates, Inc. 18905—33"Avenue W.,Suite I l7 Lynnwood,Washington 98036 (425)771-3304 Renton Fire Station J-1177 Renton,WA Test Pit Log Page 1 Test Pit TP-1 Depth (feet� Material Description 0.0-0.3 2" Asphalt over base course (Fill) 0.3-1.3 Dense, damp, dark brown, silty SAND with gravel. (Fill) .1.3-2.0 Medium dense to dense, damp, orange-brown, silty SAND with occasional gravel. 2.0-5.5 Medium dense, damp, gray, fine to medium SAND r�rith minor silt. 5.5-14.0 Medium dense to dense, damp to moist, gray-brown, gravelly SAND to sandy GRAVEL. Test pit completed at 14.0 feet on 10/1/O1. No groundwater seepage observed. No caving observed. Test Pit TP-2 � Depth (feet) Material Description 0.0-0.5 2"Asphalt over base course (Fill) 0.5-1.5 Medium dense, damp, orange-brown, silty SAND with gravel. 1.5-2.75 Medium dense to dense, damp, gray, SAND. 2.75-4.5 Medium dense, damp, gray, fine to medium SAND with minor silt. 4.5-6.5 Medium dense to dense, damp, gray-brown, gravelly SAND with occasional cobbles. 6.5-13.5 Medium dense to dense, damp to moist, fine to medium SAND with � minor silt. Test pit completed at 13.5 feet 10/1/O1. No groundwater seepage observed. No caving observed. Renton Fire Station J-1177 Renton, WA Test Pit Log � Page 2 ' , Test Pit TP-3 Depth (feet) Material Description � 0.0-0.3 2 %2"Asphalt over base course (Fill) 0.3-15.0 Medium dense, damp, gray-brown, fine to medium SAND with minor � silt. Test pit completed at 15.0 feet on 10/1/Ol. - No groundwater seepage observed. No caving observed. . , � Test Pit TP-4 Depth (feetl Material Description � 0.0-0.2 Asphalt 0.2-0.8 Dense, damp, brown, silty SAND with gravel. (Till} � 0.8-5.0 Dense to very dense,damp, gray-brown, silty SAND with gravel. (Till) 5.0-12.0 Dense, damp, gray-brown, fine to medium SAND wlth minor silt. Test pit completed at 12.0 feet on 10/1/Ol. No groundwater seepage observed. No caving observed. � � f � � i Renton Fire Station J-1177 Renton, WA Test Pit Log Page 3 � Test Pit TP-5 Depth(feet) Material Description ' 0.0-0.2 Asphalt 0.2-1.0 Medium dense, damp, brown, silty SAND with gravel. (Fill) 1.0-3.75 Medium dense to dense, damp, gravelly SAND with some silt. � 3.75-13.0 Medium dense to dense, damp, gray-brown, fine to medium SAi�ID � with occasional cobbles. � (� Test pit completed at 13 feet on 10/1/O1. No groundwater seepage observed. No caving observed. f� C � Test Pit TP-6 � Depth(feet) Material Description 0.0-0.2 Asphalt 0.2-2.0 Medium dense, damp, brown, silty SAND with gravel, concrete debris, boulders. (Fill) 2.0-2.5 Medium dense, damp, orange, silty SAND. 2.5-5.0 Medium dense to dense, damp, gray, gravelly SAND with minor silt. � 5.0-5.5 Medium dense to dense, damp, brown, silty SAND. 5.5-14.0 Medium dense to dense, damp, gray-brown, fine to medium SAND � with minor silt. Test pit completed at 14.0 feet on 10/1/O1 r No groundwater seepage observed. � No caving observed. � � � Renton Fire Siation J-1177 Renton, WA Test Pit Lo; Page 4 Test Pit TP-7 Depth (feet) Material Description 0.0-1.5 Loose, damp, brown, silty SAND with gravel. (Fill) 1.5-15.0 Medium dense to dense, darnp, gray-brown, fine to medium SAND with minor silt. Test pit completed at 15.0 feet on 10/1/O1. No groundwater seepage observed. No caving observed. � L � C ' � � � � [ � � [ 1 . � SECTION VII BASIN and COMMUNITY PLANNING AREAS Not applicable as the project does not lie within an Adopted Basin or Community Plan. � , Renton Fire Station#12 T.I.R. August 16,2002 SECTION VIII OTHER PERMITS No other permits are required. Renton Fire Station#12 T.I.R. August 16, 2002 SECTION IX EROSION/SEDIMENTATION CONTROL DESIGN A Temporary Erosion and Sedimentation Control plan has been prepared with the final construction drawing set. A combination of the foliowing Best Management Practices will be utilized: defined clearing limits, cover measures, perimeter protection by filter fabric fence, rock construction entrance, sediment traps and or rock check dams in interceptor ditches, storm drain inlet protection, and TESC measures maintenance. Two sediment traps were included in the design and the sizing calculations are included on the construction drawings. I � i I , � Renton Fire Station#12 T.I.R. August 16,2002 • - I SECTION X BOND QUANTITIES WORKSHEET A Bond Quantities Worksheet will be submitted with the final design submittal, pending any plan changes from the City of Renton's review of the proposed design. , , _ f . � ' , , � , Renton Fire Station#12 T.I.R. August 16,2002 SECTION XI MAINTENANCE and OPERATIONS MANUAL � � � � � � ; Renton Fire Station#12 T.I.R. August 16,2002 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL MAINTENANCE REQUIREMENTS F4R �� _:�:=� PRIVATELY MAINTAINED DRAINAGE FACILITIES i NO. 1 - PONDS I Malnt�nana Conditions YVh�n Mafntmana R�sula Eup�ct�d WF»n Comporant D�f�ct M N��d.d Mai�t�nanc�b P�dwrrMd li General Traeh & Dabris Any treah and deb�s which exceed 1 cubic Trash end debris cleared from III foot par 1,000 squaro feet (this is ebout equal site. 'i to the emaunt of ueeh it would take to fili up one atendard aiza otfice qarbefle can). In penerol, there ahould bs no viaua) evidence of � dumpinp. I, Poisonous Any poisonous vepetation which may No danger o}poiso�ous Vegetation co�stitute a hazard to Counry personnel or the vafletetio� whero Counry � public. Examples o(poisonous ve9etetion personnel or the public miyht include: tanay repwort,poiaon oak, etinpinq normally be. (Coordination with netdee,devils club. Seettfe/Kinp County Health Department) Pollutian Oil, yasoline, or other contaminants af one No conteminants preeent other pallon or more or any emount found thet tha� e surface film. (Coordination could: 11 cause demape to plant, enimal,or with Seatda/Kinp Counry Heelth mari�e life; 2) constitute a fire hazerd; or Department) 3) be flushed downstreem durinp rein atorms. Unmowed Grase! If faciliry is located in private residential eree, When mowinp ie needed, Ground Cover mowinp is needed when flraes exceeds 18 praeslpround cover should be inches in heipht. In othar areas, the peneral mawed to 2 inchea in hei9ht. policy ia to make the potid eite metch adjacent ( qround cover and terrain es lonp as there ia no �. inte�ference with the function of the feciliry. Rodent Halea Any evidence ot rodent holes if}acility is Rodents deatroyed end dam or ectinp ea e dam ar berm, or eny evidence of berm repaired. (Coordination with wete�pipiny throuph dam or bertn vie rode�t Seattle/Kinq County Health holee. Oepertrnent) Insecta When insecte euch es weeps and hornets tneects destroyed or removed Intarfere with meintenance ecuviHes, from eite. Tree Growth Tree prowth does not ellow mm�tenance Treea do not hinder maintenance ecceas or intarferss with maintenance activiry ectivities. Selectively cultivete (i.e., elope mowinq, rilt removel, vectorinQ, or treee such as alders for firewood. equipment movementsl. If trees ere not interferinp with access,leeve trees slone. Side Slopet of Eroaion Erodad demege ove�2 inches deep where Slopee should be etsbilized by Pa�d cause of damepe ia soll present or where usi�q eppropriate erosion control thers is potential for continued erosian. meaaure(s1; e.p., rock reinforcement, plantinQ of qrasa, comQection. Storaqe Aree Sediment Accumulated aediment that exceeda 10% of Sediment cleaned out to desiQned the desipned pond depth. pond ehape and depth; pond reseeded if necessary to control eroeion. Pond Dikes Settlements Any pert of dike which hae aattled 4 inches Dike ehould be built back to the lower than the desipn elevation, desipn elevation. Emergency Rock MisainQ Only one layar of rock exista ebave netive eoil Replace rocks to deeipn OverflowlSpillway in are five equare feet or larper, ar any standards. exposure of native soil. � A-1 l 1194 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 2 - INFILTRATION � Maint�nena Conditlon� YVh�n Maint�n�nw Re�uhs Eup�cted Wh�n ' - ComQon�nt D�f�ct 1� Na�d�d Maintenana 1� P�rforrrNd General Trash &Debris See'Ponds" Standard Na. 1 See'Ponds' Standerd No. i Poisonous See'Ponde"Stenderd No. 1 Sae 'Ponde" Sta�derd No. 1 Veqate6on Pollution See'Po�ds' Standerd No. 1 See 'Ponde' Stendard No. 1 � Unmowed Graeal See'Ponds'Standard No. 1 See'Ponds' Stendard No. 1 Ground Cover Rodent Holes See'Ponds' Standerd No. 1 See "Ponda'Standard No. 1 Inaecta See'Ponde" Standard No. 1 Sae 'Ponds' Standerd No. 1 Storepe Aree Sediment A percolatian test pit or test of faciliry Sediment is removed end/or indicates facility is only worfcinp et 90% of ite facility ia cleaned so that I desiqned capebilities. If two inches or more infiltretion system worka sediment is present, remove. accordinq to desipn. ' Sheet Cover �If Sheet cover is visible and hes more that threa Sheet cover repaired or replaced. Applicable) 114inch holes in it. Sump Flled with Any eediment and dabris fillinq vault to 10% Clean out sump to desipn depth. I Sedmiment end of depth from eump bottam to bottam of Debrie pf Applicable) ouUet pipe or obetructinp flow into the connector pipe. Flter Bags Fillad with Sediment end debris fill bap more than 1/2 Replace filter baq or redesipn Sedmiment end full, system. Debris Rock Filtere Sediment end Oebris By visual inepecdon, littte or no water flows Replace pravel in rocfc filter. ��' throuqh fllter durinp heavy rein storms. Side Slopes af Erosion See"Ponds' Standerd No. 1 See 'Ponds' Stenderd No. 1 Pond . Emergency Rock Miesing See"Ponde' Standard No. 1 Overflow Spillway Settlinp Ponda end Sedime�t Remove when 6" or mare. Vaulte Note: Sediment accumulation of mare than .25 inchas per year may i�dicate exceeaive erosion is occurring upatreem of the facility or that conveyance eyetems ere not 6einq properly maintained. The contributinp dreinape aree shauld be checked for eroeio� probleme or inadequate maintenance of conveyence syetems if excesaive aedimentetion ie noted in an infiltredon facility. Check twice a year durinQ firat 2 years of operaUon; once a year thereafter. Cleen manholes/catch beaina, repair demaged inlete/audets, claan trash recks. \ � p_Z 11/94 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL f. . NO. 3 - CLOSED DETENTION SYSTEMS (PIPES/TANKS) Mairrtenanca Co�dWons When Malntenance Resutta Expectsd Component Dafect ls Needed Vlfien Malntenanca is Periormed Storage Area Plugged Alr Vents One-half of the cross section oi a vent is Venb lree of debris and sediment. � blocked at any paint with dabrts and sediment. F Dehris and Accumulatad sediment depth axceeds All sediment and debris removed trom Sediment 10%of the diameter of the sto�aga area storage area. fot 1/2 length of storage vauR or any point depth axceeds 15%of diameter. Example: 72-inch starage tank would require cleaning when sediment reaches depth of 7 inches for more than 1/2 length of tank. Joints Between Any crack allowing materiai to ba All joints between tank/pipe sactions are Tank/Pipe Seaion Vansported into facility. sealed. Tank/Pipe Bent Any part of tank/pipe is bent out of shape Tank/pipe repairad or replaced to design. Out of Shape more than 10%of its design shape. Manhole Cover not in Place Caver is missing or only partially in placa. Manhale is closed. Any open manhole requires mairttenance. Locking Mechanism cannot be opened by one Mechanism opens with proper tools. Mechanism Not maintenanca persan with proper toals. Working Bolts into frame have less than 1/2 inch of thread (may not apply to self-{acking lids). Cover Difticult to One maintenance person cannot remove Cover can be removed and reinstalled by ! Aemove lid after appiying 80 pounds of lift Intent one maintenanca person. � is to keep covar from saaiing off access ta maintenanca. Ladder Rungs IGng County Safery Office and/a� Ladder meets design standards and Unsafe maintenance persan judges that ladder is allows maintenanca persons safe access. unsafe due to missing rungs, misalignment,rust,or cracks. Catch Basins Sea 'Catch 8asins'Standard No.5 Sea'Catch Basins' Standard No.5 �-�, � . � _. . �� I � ' � �__ � �� 1 ` � i � � 3 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 4 - CONTROL STRUCTURE/FLOW RESTRICTOR � r Malntenanu Condttlons When Malrtt�nance Resutts E�cpsctsd Component Defect la NNdad When Malntenance Is Pe�formed General Trash and Deb�is Distanca between debrie build-up and All trash and debris removed. (Indudes bottom ot orifics plats is Isss than 1-t/2 Sed(ment) feet Structural Oamags Structure is not securoly aKached to Strvcturo securoly attached to wall and manhole wall and outlet pipe structure auUet pipe. �hould support at Isas! 1,000 pounds of up or dawn pressuro. SWcture is not in upright position {allow Structure in correct position. up to 1046 irom Plumb}, Cannections to auUet pipe are not Cannections to oudet pipe are watertight; watertight and snow signs of rust, structure repaired or raplacad and works as designed. Any holes—other than designed holes— SWc:ure has no hales other than In the suucture. designed holes. Cleanout Gate Damaged or peanout gate is not watertight ar is Gate is watertight and warks as desiqned. Missing missing. Gate cannot be movad up and down by Gate moves up and down easily and is ane maintenance person. watertight. Chain leading to gate is missing or Chain is in place and works as designed. damaged. Gate is rusted over 509L of its surfaca Gats is repaired or replaced to meet area. dasign standards. �- Crifica Pfate Camaged or ConVol device is not working propeAy Plate is in placa and worke as designed. Missing due to missing,out of place,or bent arifica plate. ObsVuctions Any trasn, debris, ssdiment, or vepetation P1ate is free of all obstnictions and worlcs blocking ths plate. as designed. IOvertlow Pipe Obstruetionn Any uash or debris blocicing (or heving Pipe is free of all obstructions and works the potential of blocking) ths overflow as designed. P�Pe• Manhole $ee'Gossd Detention Systems'Standard Sse 'Closed Detention Systems' Standard No.3. No.3. Catch Basin , Sa�'Catch Basins'Standard Na. 5. See'Catch Basins'Standard No.5. i i I � \�; A--� 1/90 , . ..... . . . _..KING_.C,OUN.TY, WASHINGTON, SURFACE WATER DESIGN MANUAL . E NO. 5 - CA TCH BASINS Malntenancs Co�dttlons When Maintenancs Raautts Expected Compo�ent Defect is Ne�dsd When Maintenane�(s Perfortned General Trash E�Oebris Trash or debris of mare than 1/2 cubic No Vash or debris loeated immediately in (Includes foot wnich is located immediately in front front of catch basin opening. Sediment) af the catch basin opening or is blocking capaciry of basin by more than 10%. Trash or debris (n tha basin) that No trash or debris in the catch basin. exceeds 1/3 the depth from the bcttom of basin to invert of the lowest pipe into or out of the basin. Trash or debris in any inlet or outlet pipe Inlet and outlet pipes free of Vash or blocking more than 1/3 of its height. debris. Oead animals or vegetation that could No dead animals or vegetation presant generate odors that would cause within the catch basin. complaints or dangerous gasas (e.g., methane�. Deposits af garbage exceeding 1 cubic No condition present which wouid atttact foot in volume. or support the breeding of insects or rodants. Structural Damage Corner of irame extends more than 3/4 Frame is even with curb. to Frame and/or inch past curb tace into the street (i} Top Sfab applicable�. Top slab has holes larger than 2 square Top slab is free of holes and cracks. inches or cracks wider than 1/4 inch (ntent is to make sure all material is � running into tne basin). Frame not sitting flush on top slab, i.a., Frame is sitting flush on top slab. separation at more than 3/4 inch of the trame from the top slab. Cracks in Basin Gacks wider than 1/2 inch and longer Basi� replaced or ropaired to design Walla/Bottom than 3 laet, any evidenca of soil particies standards. entering catch basin throuqh cracks, or maintenanca person judges that structure is unsound. Cracks wider than t/2 inch and longer No cracks moro than t/4 inch wide at the t�an t foot at the joint of any inlet/outlet joint o(inlet/outlet pipe. pipe or any evidanu of soil particles sntering catch basin througn cracks. Sattlement/ Basin has settled mare than 1 inch or has Basin replaced or rapaired to design Misalignment rotated more than 2 inches out of standards. alignment. Firo Hazard Prasence of chemicals such as natural No flammaole chemicals present. qas,oil,and gasoline. Vegetatlon Vagetation growing across and blocking No vegetation blocking opening to basin. more than 10°6 of the basin apening. Vagetation growing in inlet/outiet pipe No vegetation or root qrowth presant. joints that is more than six inchas talt and less than six inches apart. Pollution Nonflammable chemicals of more than No pollution present other than sucface 1/2 cuhic foot per three feet of basin film. length. F:= " A-5 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 5 - CATCN BASINS (Continued) nf ; Malntenanee Co�dFtlona Wh�n Malntsnanc� R�wtta Expaeted � Compon��t De(�ct la NMd�d When Mainte�anee la Performed Catch Basin Cover Cover Not In ?laca Covar is missing or only partialiy in place. Catch basin cover is clased. Any open catch basi�requires maintenance. Locking Mechanism cannot bs opensd by ane Mechanism opens with p�oper toals. AAachanism Not maintenance parson wiih proper tools. Working Bolts into frame havs lau than t/2 inch of thread. Cover Difficult to One maintenance person cannot remove Cover can be removed by one Remove lid after applying 80 Ibs,ot tift; intent is mainte�anca person. keep cover irom saaling off access to maintenance. ladder Ladder Rungs ladder is unsafe due to missing rungs, Ladder meets design standards and Unsafe misalignment,rust,cracks,or sharp allows maintenance person safe access. _ edges. Ivtetal Grates Grate with opening wider than 7/8 inch. Grate openings meet design standards. (if applicable) Trash and Debris Trash and debris that is blocking more Grate frae of trash and dehris. than 2096 of grate su�face. . Damaged or Grate missing or broken membar(s)of Grate is in place and meets design Missing the.qrate. standards. ��. i `� A� 1/90 -�---K,I-N-G.--C_OUNT•Y,_.WA�HII�f.G.T.QN,.,S_LLRF_�CE,WA:TER_DESI_GN MANUt� L. , E NO. 6 - DEBRIS BARRIERS (e.g. Trash Racks) Malntenanca Conditfo�s When Malrttenanc� R�sutts Expected Campo�ent De(ect Is Need�d VYhen Malrttenanca is Performed Generai Trash and Debris Trash or debris that ia plugging mo�s Barrier cfear ta recefvs capaaty flow. than 20%of the openings in tha harrier. Metal Oamagsd/Missing Bars ars bent out of shape mors than 3 Bars fn place with no bends more than Bars inchea. 3/4 inch. Bars are missing or e�tire barrier is Bars in place according to design. misaing. Ban are loose and rust is causing 50% Repair or replace barrier to design deterioration to any part of barner, standards. \ �;: A-7 1�� KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 7 - ENERGY DISSIPATORS y ,. Malntenance Conditiona When Malntenana R�sutts Expecisd Component Detsc! fs Nesded When Malntenanc� is Perform�d External: Rock Pad Mtssi�g or Moved Only one layer of rxk exiats above native Replace rocks ta design standard. Fiock soil in area five square feet or larger,or any exposuro of native soil. Dispersion Trench Pipe Plugged with Accumulated sediment that excaeds 20% Pipe eleaned/flushed so tfiat it matches Sedimant of the design depth. design. Not Dfscharging Vfsual evidenee of water discharging at Trench must be radesigned or rebuilt to Water Properly concentrated points along trench (normal standard. condition is a'sheet flow'of watar alonq trench). Intent is to prevent erosion damage. Perforations Over 1/2 of perforatians in pipe are Clean or replace perforated pipe. Plugged plugged with debris and sediment. Water Flows Out Maintenanca person observes water Facility must be rebuilt or radesigned to Top of'DisVibutor' flowing out during any starm less than sWndards. Cacch 3asin the design storm ar it is causing or appears likely to causa damage. Racaiving Araa Water in recaiving area is causing or has No danger of tandslides. Over-Saturated patential o(causing landslide problems. !nternal: Manhole/Chamber Wom or Oamaged Structure dissipatlng flow deterioratas to Replace structure to design standards. Posts, Batfles, 1/2 or original siza ar any concentrated � Sides of Chamber wom spot exceeding one s4uare foat which would make sUuaure unsound. Other Defects See 'Catch Basins' Standard No. 5 Sae 'Catc7 3asins' Standard No. 5 1/9a �-8 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL F . NO. 8 - FENCING Maintenance Conditlo�s Wh�n Main�snanc� Resutts Exp�ctsd Component D�fec! Is N«d�d Wh�n Maintanane� Is Performed General M(saing or&oken Any defect In the fsnce that permits sasy Pnrts in place to p�ovide adequate Parts entry ta a tacility. seeurity. Parts broken or missine. &oken or missing parta replacad. Erosion Etosion more than 4 inchea high and 12- No opening under the fence that excaeds 18 I�ehen wide permitting an opening 4 inchea in height. undet a fence. Wirs Fencea Damaged Parts Posts out of plumb mors than 6 inchea. Posri plumb to within t-i/2 inchea. Top roils bent mars than 6 inches. Top rail free of benda greater than 1 inch. Any part ol fenca (ncluding posts, top Fence is aligned and meets design rails, and fabric) more than 1 foot aut ot �tendards. design alignment. Miuing or loase tension wirs. Tension wire in place and holding tabric. Missing or loose bar�ed wire that is Barbed wiro in place with less than 3/4 sagging more than 2•1/2 inches between inch sag berivean posts. pasts. Extension arm missing, broken, or bent Extension arm in placa with no bends out of shape more than t-1/2 inches, larger than 3/4 inch. Deteriorated Paint Part or parts that have a rusAng or scaling Structurally adequate posts or parts with or Protactive condition that has affected structural a uniform p�otective coating. Coating adequacy. , ( • Openings in Fabric Openinqs in fabric are such that an& No apenings in fabric. � inch�iameter ball cauld fit through. I i �I �•. A-9 1�9Q KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL , NO. 9 - GATES �I � � Malntenancs CondFtlons Wh�n Malrtbnana R�sutts Ex�ctsd Compone�t Def�ct Is N«d�d WT1M Malflt�flaflC�(s Periormed General Damaged ar Miasing gate ot lodcing devicea. Gatss and Ixking davices In place. Missing Membero &oken or missfng hingea such that gate Hingea intact and lubed. Gate ia warking cannat be sasity apened and dosed by a freely. mafMenance person. Gats la out af plumb maro than 6 fnches Gate is alignad and vertical. and more than 1 foat out of design alipnment Missi�g sVetcher bat,sVatcher bands, SVetcher bar, bands, and tfes in piace. • and ties. Openin9s ln Fabric See"Fendng'Standard Na.8 See'Fencinq' Standard No. p f t �� 1;�'�.i I A-10 -� KING COUNTY, wASHINGTON, SURFACE WaTER DESIGM t�f� i`� J� � � NO. 10 - CONVEYANCE SYSTEMS (Plpes & Ditches) Malntanance Co�dWons When Maintenancs Resutts Eupected Component Delsct Is Nseded When Malrrtenance [� F'weff�ct�t� Pipes Sediment&Debris Accumulated sediment that exceeds ZO% Pipe deaned ot all ssciict�c.r�(ar�ci deh�ls. of the diametar of the pips. Vegetation Vagetatlon that reduces hss movement of All vegetatian removod so�reafcr tlotvs water through pipee. ireely through pipea. Damaged Proteclive coating is damaged; rust ia Pipe repaired or rep{�csu. causing mwe than 50%deteriorallon to any part af pipa. Any dent that decreasea ths uoss section Pipe repaired or replscad. area of pipe by mare than 2096. Cpen Ditches Trash $Gebris Trash and debris exceeds 1 cubic foat Trash and debris clCP.rcC�irGm�[(ici�na. per 1,000 square feet of ditch and slapes. Sediment Accumulatad sedimant that exceeds 20% Ditch cleaned/tlushr.d af e.:t �ac�fn;ert%end af the design dapth. debris so that it matcf��<:c�tc•�i�t�.. Vegetation Vegetation that reduces froe movement of Water flows freely throu{;:`� _�:i::;;eC. watet through ditches. Eroslon Damage ta See'Ponds'Standa�d No. 1 See'Ponds'Stand�rG h?o. `. Slopes Aock Lining Out of Maintenanee person can sea native soil Replace rocks to de�ic;r� ss,:;:c�';:r�+.. P1ace or Missing (K beneath the rock lining. .�,pPlicable) l , Catch Basins Sae 'Catch 8asins'Standard Na.5 Sae 'Catch Basina'�t�;��dr.rc� �:�. S Debris Barriers See'Debris Barriera' Standard No.6 See'Debris Barriers'�=1.c��_:r:i ��:�,fi (e.g., Trash Rack� � . A-11 � i90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 11 - GROUNDS (Landscaping) � i , Malntenane� Co�dklons Wh�n Malnt�nanct Resutts Exp�ct�d Component D�fect la N�ed�d Whe� Mafntsnancs Is Periormsd General Weeda Wseda growing in mors than 2096 ot the Weads prasont in less than 546 af the , (Nonpoisonous) landscaped arsa (Vaes and shrubs anly). Iandscapsd arsa. Safaty}-iazard My pressnce af poiso�ivy ot other No poisonous vegetabon present in a poisonoua vagetatlon. Iandscaped area. Trash or litter Paper,can, bottles,totalling more than 1 Arsa dear of Iftter. aibic foot within a Iandscaped area (Vees anQ shruba only) of 1,000 squars fest Trees and Shtubs Damags• Limbs or parts af Vees or shrubs that ate Troea and shrubs with leu than 5%of;he � split or broken which aHect more than total foliage with split or broken limbs. 25%ot the Wtal foliaee af ihe tree or shrub. ' Trees ar shruba that have been blown Tree or shrub in placa free of injury. down or knxked over. Trees ar�hrubs which are not adequately Tree or shrub in place and adequately supported or ue leaning over,causing supported; remove any dead or diseased exposure of the roats. trees. d �_ \, A-12 1/90 . . KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL � NO. 12 - ACCESS ROADS/EASEMENTS Malntenanee CondlUons When Malntenanc� Reautts Expected CamponeM Defset Is Needad Whert Mal�tenance Is Performed General Trash and Debris Trash and debris exceeds 1 cubic foat Trash and debris cleared from site. pe� 1,000 square feet, (.e.,Vash and debria would fill up one standard size garbage can. Blocked Roadway Debris which could damage vehide tires Floadway free of debris which could (glasa or metaJ). damage tires. Any abstructions which reduce clearance Roadway overnead clear to 14 feet high. above road surface to less than 14 faet. Any obstructions restricting the access to Obstruction removed to allow at least a a 10-to 12-toat width tor a distance of 12-foot accsss. more than 12 feet or any point restricting access to less than a tafoot width. ftoad Surface Settlament, When any surfaca defeci exceeds 6 Road surface uniformly smooth with no Potholes, Mush inchas in depth and 6 squa�e feet in area. evidence of settlement, potholes,mush Spots, Ruts in general, any su�iace defect which spots, or ruts. hinders ar preve�ts maintenance axess. Vegetadon in Fioad Weeda growing in the road surface that Raad suttace free of weeds tatler than 2 Surface are more than o inches tall and less than inches. 6 inches apart within a 40o-square-foot !� area. I Shouiders and Erosion Damage Erosian within 1 foot oi the roadway more Shaulder}ree of erosion and matching ' Ditches than 8 inches wide and 6 inches deep, the surrounding road. l Weeda and &ush Weeds and brush exceed 18 inches in Weads and brush cut to 2 inches in height or hinder maintenance accesa. height or clearad in such a way as to ailow maintenance accass. � A,� t/'90