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Home My WebLink About03355 - Technical Information Report BAIMA & HOLMBERG INC. ►, . �'�i .�cl � TECHNICAL INFORMATION REPORT fo r Hoquiam Court Short Plat August 11, 2005 C:rv��,D lz��r G(�, �G�✓lyi�� ', � i Z; F/ � ��1L'PE �` oF "'As tiQ.��, �i ? � , 2 � �� n. �� 11332� �t;,� �SSIONA�� E�PIRES ll i'30 j 0 Baima & Holmberg, Inc. Job No. 1673-026 Prepared For Basic Ventures 18211 240th Avenue SE Maple Valley, WA 98038 .' .._,.+.r/ 100 FRONT STREET SOUTH • ISSA(�UAH • WASHINGTON • 98027-3817 • (425) 392-0250 • (425)391-3055 TABLE OF CONTENTS SECTION TITLE 1 PROJECT OVERVIEW 2 CONDITIONS AND REQUIREMENTS SUMMARY 3 OFFSTTE ANALYSIS 4 FLOW CONTROL AND WATER QUALITY FACILTTY ANALYSIS AND DESIGN 5 CONVEYANCE SYSTEM ANALYSIS AND DESIGN - 6 SPECIAL REPORTS AND STUDIES 7 OTHER PERNIITS 8 ESC ANALYSIS AND DESIGN 9 BOND Q[TANTITIES,FACII�TTY Stif�vIlVIARIES,AND DECLARATION OF COVENANT 10 OPERATIONS AND MAINTENANCE MANUAL . i , SECTION 1 PROJECT OVERVIEW - Project Overview � This project involves the development of a 0.95-acre parcel into six single-family lots. The site is located on the east side of Hoquiam Avenue NE, at 810 Hoquiam i Avenue NE. The site is about '/z covered with an existing house, garage, sheds, I driveway and lawn, with the remainder covered with woods. The site slopes down to the east at about 1%to 8%. Per the SCS soil maps, the site is underlain with Alderwood Series sandy loam over glacial till. The recently constructed plats of Wedgewood and Aspen Woods are immediately adjacent to the north, south and east sides of the site. Upstream Drainage Little if any drainage runs onto the site from offsite areas. Downstream Drainage Onsite runoff sheetflows at about 5%to 10% east drain through the wooded property to the east into the 12" CB/pipe Aspen Woods storm system (A). This dischazges into a detention and water quality pond about 350' downstream from the site (B). At about 800' east of the site, the pond outfall drains into an adjacent wetland buffer(C) then into Honey Creek. Honey Creek flows northeast to well beyond '/4 downstream from the site. There were no apparent drainage problems along this do��°nstream drainageway. Proposed Drainage Controls Onsite flows will be picked up in a CB/pipe storm system and routed to an onsite, combination Level 2 detention vault and Basic Water Quality wetvault before being released into the Aspen Woods storm system. Frontage water quality control will be provided with Basic Water Quality dead storage in an oversized 72" CB. King County Department of Development and.Environmental Services TECHNICAL INF�RMATION REPORT (TIR) WORKSHEET ; Part1 �P.ROJECTOWNER,AND ;Part2 :'PROJECT_LOCATION.AND - PROJECT�ENGINEER` � -:DESCRIPTION Project Owner � ` Pro'ect Name `R�c G j ]$rN�f�� e�6� u t r4�n,� Gt'JU 12� Address ` � Z � n ,' Location � /•t-v - �� Township Pho�� -' ,�r3�� 333 9 �y � Ran e Projec Engineer •••••••••••••Section ' L1�1 Compan 1 � Address/Phone — �— Part 3 TYPE OF PERMIT Part:�i .�OTNER-REUIEWS AND;P.EftM1T,S,, ,=.,. .� _._ ; AFP.L�ICATION`=' ..� _ ', ;� � ,: ,_:. , , . ,. . . _ _ Subdivison � � DFW HPA Shoreline Management x Short Subdivision COE 404 Rockery � Grading DOE Dam Safety Structural Vaults Commercial FEMA Floodplain Other � _ Other COE Wetlands . P.art�_�SITE CbMMUNfTY:AND flRAtNAG.EBASIN ... _� ` :-�: .. -9� Community �'C`� � � ��. \ IV . Drainage Basin �/ Part 6 SITE;GHARACTERISTICS=-; ' - � River Floodplain Wetlands Stream Seeps/Springs Critical Stream Reach High Groundwater Table Depressions/Swales Groundwater Recharge Lake � , Other Sfeep Slopes � , - - Patt 7 .;SOILS = - � . . :�. - ` � Soil Type Slopes Erosion Potential Erosive Velcoties � ��Y-[�LL.�d�X�,jj 1l'�LO l�/�'�. Additional Sheets Attached . . . . , . ,. , . Pait 8:, DEVELOPMENT°LiMITATIONS � . � - REFERENCE LIMITATION/SITE CONSTRAINT Ch. 4-Downstream Analvsis ��j �it �ts�/�t/L.S Additional Sheets Attached Part�9 ESC�REQUIREMENTS - _ " � - -�> ��. _ - - - .�-: - - MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION AFTER CONSTRUCTION I Sedimentation Facilities Stabilize F�cposed Surface . Stabilized Construction Entrance .. Remove and Restore Temporary ESC Facilities Perimeter Runoff Control �- Clean and Remove All Silt and Debris Clearing and Graing Restrictions Ensure Operation of Permanent Facilities ' Cover Practices Flag Limits of SAO and open space Construction Sequence preservation areas Other Other � �Part 10 '.SURFAGEWATER SYSTEM . ' Grass Lined Tank Infiltration ��ethod of Analysis Channel auit Depression G J Pipe System Compensation/Mitigati Energy Dissapator Flovr Dispersal on of Eliminated Site Open Channel Stora e Wetland Waiver 9 � Dry Pond � Stream Regional Wet Pond Detention = Brief Description of System Operation � G✓ /9'l IN ��- �` � Facility Related Site Limitations v�L 1 Reference Facility Limitation �ait�1.�S�RUGTU.F�AL ANALYSfS�� ,_._,.; 2Party2__'EASEMEN�SI�RACTS � ��; , ... _ � _ _ �_ ,� _ �. _ _ _._ - _ . > ast in Place Vault rainage Easement Retaining Wall Access Easement ' Rockery>4' High Native Growth Protection Easement : Structural on Steep Slope Tract � Other . � Other � � Part73:>SIGNATURE=OF PR�F:ESSIONAL�ENGINEER.._�..._ .- - � !or a civil engineer under my supervision my supervision have visited the sfte. Actual site conditions as observed were incorporated into this worksheet and the attachments. To the best of � my knowledge the informati�n provided here is accurate. 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Plani .. _... . ..._,__..__._.._.._ .�_r.�;_5...- - _ ._.. .. .- ---- _� --- deiail�obteined from U$�S ��minute series map 50� 10000 feet Polyo 10,0f �.--� ------- ------.-._ .. ..._____ _ ._ _ _ _ _..-----�—rro-rm - _ � SDILS MAp SHEET N I' SECTION 2 CONDITIONS AND REQITIRMENTS S Y � November 1, 2005 OFFICE OF THE HEARING EXAMINER � CITY OF RENTON Minutes APPLICANT/OVl!'NER: Joe Pruss Basic Ventures, Inc 18211 240'h Avenue SE Maple Valley, WA 98038 CONTACT: Tom Redding Baima&Holmberg, Inc. 100 Front Street S Issaquah, WA 98027 Hoquiam Court Short Plat � LUA OS-099, SHPL-H LOCATION: 810 Hoquiam Avenue NE ' SUMMARY OF REQUEST: Hearing Examiner Short Plat approval for a six(6) lot I subdivision of a 0.95-acre site. SUMMARY OF ACTION: Development Services Recommendation: Approve subject to conditions DEVELOPMENT SERVICES REPORT: The Development Services Report was received by the Examiner on October 11,2005. PUBLIC HEARING: After reviewing the Development Services Report, examining available information on file with the application, field checking the property and surrounding area; the Examiner conducted a public hearing on the subject as follows: M INU'I'F S Tlie following minules are a sun:mary oJ1he October 18, 2005/eearing. TI:e legal record is recorded on CD. The hearing opened on Tuesday,October 18, 2005, at 9:02 a.m. in the Counci(Chambers on the seventh floor of the Renton City Hall. Parties wishing to testify were affirmed by the Examiner. The following exhibits were entered into the record: Exhibit No. 1: Yellow file containing the original Exhibit No. 2: Neighborhood Detail Vicinity Map application, proof of posting, proof of publication and other documentation ertinent to this re uest. Exhibit No. 3: Preliminary Short Plat Eshibit No. 4: Pre(iminary Topography, Road, Utilities,Tree, Landsca in , Grading and Draina e Hoquiam Court Short Plat File No.: LUA-0�-099, SHPL-H November l. 200� Page 2 Exhibit No. 5: Zoning Map Exhibit No. 6: Letter from City of Renton Public V4'orks a rovin ri ht-of-vva width modification Exhibit No. 7: Overall circulation map of area The hearing opened with a presentation of the staff report by Jennifer Hennin�, Senior Planner, Development Services, City of Renton, 1055 S Grad}� Way, Renton, Washington 98055. The site is located in the Residential- 8 zoning designation and is currently developed w�ith an existing single-family residence and outbuildings. This site is located on the east side of Hoquiam. The area has been undergoing rapid gro�vth and this is one of the last remaining parcels to be subdivided. T��o of the proposed lots ��ould face Hoquiam and the remaining four lots would take access via an extension of NE 8"' Circle from the road stub in the approv.ed plat of Aspen Woods. The existing home and outbuildings would be removed. NE 8`�'Circle would be dedicated and be 26-feet of right-of-way and would allow improvements to be constructed on the south side of the site and would connect into Aspen Woods. The slope on the site is a maximum of 8%. The approximately 25 trees existing on site would be removed as part of the development of the site. City standards do require some landscaping to be done on the new lots. The subject site is designated Residential Single Family(RSF)on the Comprehensive Plan Land Use Map. The proposed plat is consistent with the pertinent Comprehensive Plan policies. Each of the proposed lots exceeds 4,500 square feet,and the parcef is considered an infill development. The net density for the site is 7.75 dwelling units per acre which is consistent with the density allo:ved in the R-8 zone. Lot 2 �+�ould be considered a corner lot and as such would need to be 60-feet in ��•idth, the lot line needs to be shifted between Lots 1 and 2 to allow Lot 2 to achieve its appropriate 60-foot width. The proposed lots comply ��ith arrangement and access requirements of the subdivision regulations. Each of the remaining lots satisfies the minimum lot area and dimension requireinents of the R-8 zone after the realignment of Lots 1 and 2. Tlie applicant proposed to provide drought-tolerant landscaping and trees within a 5-foot wide landscaping strip. Fire, Traffic and Park Mitigation Fees are to be imposed as condition of short plat approval. The site is located ��ithin the boundaries ofthe Renton School District. The School District has indicated that the�� can accommodate the additional students. 'The site ,lopes to the ea�t at about 1",'0-8°o. Onsite runol�i'sheet tlo44s at approximatel�� 5°'o to 10°ro east tlirou�li the approved Aspen �Voods subdivision. Little if any drainage rw�s onto the site fro�n offsite areas. The proposal shall be designed to be in compliance with the 1998 King County Surface Water Manual, Level 2, for onsite water quality treatment and runoff detention. A drainage report was prepared and submitted by Baima & Holmberg at the time of application for a short plat. The required flow control and water quality will be provided ��ith a combination Level 2 detention vault and a«�ater quality vault. The applicant propc�ses a combined detention/water quality vault within an easement across the front(south side)of Lots 5 and 6. W'ater service is within the King County Water District No. 90. A certificate of water availability has been provided. The extension and replacement of the 8" main on Hoquiam Avenue NE ��ill be required, as ��ell as Eloquiam Court Short Plat File No.: LUA-0�-099. SI(PL-I1 November l, 200i Page 3 dedication of any reyuired easements. There is a 16-inch ��ater main and an 8-inch sewer main within Aberdeen Avenue NE. Shupe Holmberg, Baima& Holmberg, Inc., ]00 Front Street S., Issaquah, WA 98027 stated that they are in agreement with staff. 1�he modification to Lots 1 and 2 is acceptable and �vill be corrected. The turning radius for Lot 2 �vill be accommodated. Joe Pruss, Basic Ventures, Inc., 18?1 1 ?40`�' A��enue SE, I�'Iaple Valle��, ��'A 98038 stated that they��ould like to incorporate the landscape requirements on the site plan at the time of final platting. Neil Watts, Director, Development Services Division stated that the Landscaping Code is fairly news and does have a variety of glitches that staff is aware of, unfortunately they have not been corrected as yet. The landscape plan is required for recording the short plat; however,the actual installation of the landscaping must he done before the final inspection of tlie homes. In regards to the street modifications, Aspen Woods is installing exactly the same right-of-way width and street dimensions as was approved for modification for this project. That wi(I be 26-feet of right-of-way�vith 20-feet of pavement and curb, gutter and side�valk along the north side. No parking will be allowed on either side of tt�c street. For this project, the street modification will either be connected all the way through to Aspen Woods or a temporary turn-around will have to be provided subject to Fire Department approval. As to the turning radius off of Hoquiam, that will also need to be discussed with the VVedge��-ood 2 people for the south side of the new NE 8`�'Circle. This will be a standard street intersection,a public street. A public street allows for the enforcement of"no parking" requiremea�ts by the police department. A side��alk �vill be provided on the north side of the street. This conceptual drainage plan was submitted under tlle 1998 Manual, the City Code still required the 1990 Manual, however, almost every project is required to adhere to the 1998 standard. All the projects in this area have been required to adhere to the 1998 I�lanual, Level 2. This project proposes that, but since they did not have to undergo SEPA that condition does not exist on the project. He would like to have the 1998 Manual listed as a condition of approval. The storni water system for this project has a detention vault, which is for both detention and water quality. It is partialiy located in the rigl�t-of-way, which is okay for Fire and City policies. The issue for tiie i.ity of Renton is that it is to be privately owned and maintained by the owners of this small short plat. He would like to see a homeo�vner's association,which is somewhat unwarranted for a plat of this size, but it is an option or that there be a maintenance agreement of the six property owners for maintenance of this drainage facility. The joint maintenance agreement seems most likely. There is a school boundary issue that comes up behueen these plats. It appears that this plat is in Renton School District. They �vill check after the hearing, but will let us know which schoo) district is actually affected by this plat. There are no �+�ater district development charges required for this project. Mr. Holmber�stated that regarding the drainage, they propose to provide Level 2 detention for the 1998 King County Manual that is consistent��ith the other developments in the area. A Joint Maintenance Agreement will be set up for the drainage facility and storm system. Hoquiam Court Short Plat ', File No.: LUA-OS-099, SHPL-H November 1, 2005 Page 4 I Mr. Pruss stated that they have done several vaults in the City all ��ith small lot counts,they do have a joint tnaintenance agreement that has previously been used and approved. The Examiner cal led for further testimony regarding this project. There was tio one else wishing to speak, and no further comments from staff. The hearing closed at 9:58 a.m. FINDINGS,CONCLUSIONS �C RECOR'IMENDATION Having reviewed the record in this matter,the Examiner no�� makes and enters the foliowing: '� FINDINGS: 1. The applicant,Joe Pruss, Basic Ventures, Inc., filed a request for an approval of a short plat. 2. The yellow file containing the staff report,the State Environmental Policy Act(SEPA)documentation and other pertinent materials was entered into the record as Exhibit#1. 3. The Environmental Review Committee(ERC), the City's responsible official determined that the I proposal is exernpt from environmental review. I 4. The subject proposal was reviewed by all departments with an interest in the matter. I' 5. The subject site is located at 810 Hoquiam Avenue NE. The subject site is located on the east side of Hoquiam just north of what�vill be NE 8th Circle. 6. The map element of ihe Comprehensive Plan designates the area in which the subject site is located as suitable for the development of single family uses,but does not mandate such development«ithout consideration of other policies of the Plan. 7. The subject site is currently zoned R-8 (Single Family - 8 dwelling units/acre). 8. The subject site was annexed to the City with the adoption of Ordinance 5017 enacted in November 2004. 9. The subject site is approximately 138 feet�vide(north to south) by 301 feet deep. The parcel is approximately 0.95 acres or 41,549 square feet. 10. An existing home and outbuildings will be removed to accommodate redevelopment if the plat is approved. 1 1. The subject site slopes moderately do��-n��-ard to the east at between 1%and 8%. Storm�i�ater sheet flows off the site in an easterly direction. - 12. Trees, approximately 25, would be removed to accommodate building pads and roads. Code requires the planting of street trees and landscaping along the road��ay. 13. The six lots would be generally aligned west to east although Proposed Lots 1 and 2 would both face Hoquiam. The remaining lots, Proposed Lots 3 to 6,would be aligned along the north side of a new public street and take access front the ne�v street. Hoquiam Court Short Plat File No.: LUA-0�-099, SHPL-H November 1, 200� Page 5 14. Proposcd Lot 2 at the northeast corner of the intersection of Hoquiam and the ne��-public road is a corner lot. Its lot width did not reflect the code requirements for a corner lot in that it«�as designated at 56 feet ��ide whereas 60 feet is required. The applicant indicated that Proposed Lot 1 could be narrowed allowing Lot 2 to meet code. 1 S. The new street would be NE 8th Circle. It �4�ould extend from Hoquiam on the west to an existing stub road in the Aspen Vdood plat east of the subject site. That road in Aspen Woods �vas originally an easement but the City required it be a public roadway. It will now be connected through to Hoquiain. It �vill be a 26-foot�vide right-of-way with 20 feet of pavement. 16. The density for the plat would be 7.75 d��-elling units per acre after subtracting 7,827 square feet for roadways. 17. The subject site is located within the Renton School District. The project is expected to generate approximately 2 school age children. These students would be spread across tlle grades and would be assigned on a space available basis. 18. The development will increase traffic approsimately 60 trips for the six homes. ApproximaYely ten percent of the trips, ur approtimately 6 additional peak hour trips �vill be generated in the n�orning and evening. 19. Storm�vater wil I be handled by a detention system coiistructed in the front of Proposed Lots � and 6 in an easement for that purpose. lt would provide both detention and water quality treatment and meet King County's 1998 manual, Level 2 requirements. 20. Sewer�+�ould be provided by the City but will be dependent on a line constructed as part of the Aspen Woods project east of the site. I 21. Water wou(d be provided by Water District 90. A certificate of availability was provided. 22. The City has adopted mitigation fees for transportation improvements, fire services and parks and recreational needs based on an analysis of the needs and costs. These fees are applied to new development to help offset the impacts new homes and residents have on the existing community and tl�e additional demand for services. CONCLUSIONS: 1. The proposed short plat appears to serve the public use and interest. The proposal creates six rectangular lots that meet or can meet code requirements for lot width and lot area. The lots�:�i have regular, right angle property lines. 2. The proposal creates additional R-8 detached single-family housing choices for residents in an area with urban services. 3. New plats are required, by State regulations,to make provision for the i�npacts of its new homes and future residents. The new homes proposed for tl�is plat should not overtax the City's infrastructure but the applicant should help accommodate new residents and their demand for services by paying the appropriate fees for parks, fire and transportation. i ' Hoquiam Court Short Plat File No.: LUA-OS-099, SHPL-H November l, 200� Page 6 �,I 4. The applicant shall ha��e to modify the originally proposed widths for Proposed Lots 1 and 2 to ' accommodate Lot 2's corner lot status. The lot�vidth for Proposed Lot 2 shall be not less than 60 feet ' wide. '� 5. The applicant will have to submit the dedication for the ne�v street to the City Council. In regard to I roads, the link through Aspen Woods shall be required prior to final occupancy of this plat. �, 6. In conclusion, the Proposed ShoR Plat appears to blend hannoniously with its surroundings while allowing infill development in a growing area of the City. DECISION: The Six-Lot Short Plat is approved subject to the following conditions: II 1. The applicant shall dedicate a 26-foot strip along the south property line of the site as right-of-way for NE 8`h Circle prior to short plat recording. 2. The applicant shall comply with all requirements and conditions stipulated in the letter from the City's Public Works Department,dated October 7, 2005 regarding the approved right-of-way width modification request for NE 8`�'Circle. 3. The public roadway link through Aspen Woods, or turnaround, shall be required prior to final I occupancy of this plat. I 4. The applicant shall pay the appropriate Traffic Mitigation Fee based on $75.00 per new average daily trip attributed to the project prior to the recording of the final plat. 5. The applicant shall pay the appropriate Fire Mitigation Fee based on a rate of$488.00 for each new single-family residence prior to the recording of the final plat. 6. Tl�e applica�lt shall pay the appropriate Parks Mitigation Fee based on$�30.76 per new-sii:gle-family lot �I prior to the recording of the final plat. 7. The lot width for Proposed Lot 2 shall be not(ess than 60 feet wide. 8. The plat shall comply with the 1998 King County Stormwater Manual, Level 2 controls. 9. A Joint Maintenance Agreement shall be set up for the drainage and storm system facilities. ORDERED THIS 15t day of November 200� �— FRED J. KAUF N HEARING EXA INER TRANSMITTED THIS l S`day of November 2005 to the parties of record: Hoquiam Court Short Plat File No.: LUA-0�-099, SHPI_-�� November 1, 2005 Page 7 Jennifer Henning Neil Watts Joe Pruss 10>j S Grady Way 1055 S Grady �Vay Basic Ventures, Inc Renton, WA 980�5 Renton, Vb'A 98055 1821 1 240`�'Avenue SE Maple Valley, WA 98038 Shupe Holmberg Baima& Holmberg, lnc. 100 Front Street S Issaquah, WA 98027 TRANSMITTED THIS 1 S`day of November 2005 to the following: Mayor Kathy Keolker-Wheeler Stan Engler, Fire Jay Covington, Chief Administrative Officer Larry Meckling, Building Official Julia Medzegian, Council Liaison Planning Commission Larry Warren, City Attorney Transportation Division Gregg Zimmerman, PBPW Administrator ��Utilities Division Alex Pietsch, Economic Development Neil Watts, Development Services Jennifer Henning, Development Services Janet Conklin, Devel r�n •��f � �� Stacy Tucker, Development Services King County Journal Pursuant to Title IV, Chapter 8, Section 100Gofthe City's Code, requcst 1ur recon,i�lerxtiun n�u�t be t►1c�l in writing on or before 5:00 n•m., November 15,2005. Any aggrieved person feeling that the decision of thc Examiner is ambiguous or based on erroneous procedure, errors of law or fact, error in judgment, or the discovery of new evidence which could not be reasonably available at the prior hearing may make a written request for a review by the Examiner within fourteen(14)days from the date of the Examiner's decision. This request shall set forth the specific ambiguities or errors discovered by such appellant, and the Examiner may, after revie��of the record, take further action as he deems proper. An appeal to the City Council is governed by Title IV, Chapter 8, Section 110, which requires that such appeal be filed with the City Clerk, accompanying a filing fee of$75.00 and meeting other specified requirements. Copies of this ordinance are available for inspection or purchase in the Finance Department, first floor of City Hall. An apneal must be filed in writing on or before 5:00 p.m.,November 15,2005. If the Examiner's Recommendation or Decision contains the requirement for Restrictive Covenants,the executed Covenants will be required prior to annroval b�� City Council or final processin�of the file. You ma3� contact this office for information on formatting covenants. The Appearance of Fairness Doctrine provides that no ex parte (private one-on-one) communications may occur concerning pending land use decisions. This means that parties to a land use decision may not communicate in private with any decision-maker concerning the proposal. Decision-makers in the land use process include both the Hearing Examiner and members of the City Council. All communications concerning the proposal must be made in public. This public communication permits all interested parties to kno�v the contents of the communication and �vould allow tl�em to openly rebut the evidence. Any violation of this doctrine would result in the invalidation of the request by the Court. The Doctrine applies not only to the initial public hearing but to all Requests for Reconsideration as�vell as Appeals to the City Council. 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MAILL iRC[ � �� p ��T.�� v'� BAIMA & HOLMBERC INC. pC WAT[I1 VAL�F a i T-'� �t T�Q � ��KnApf `��OT�'Vfj�� E N 0�N E E� S k S U R V E Y 0 R 5� �,,, HOQUTAM COURT yyr�7 �oo rno�T sn��tt�ouTM iss,�W,u�,w�maHoro� �eov m IElI►NbK/EDCSTAL �l_�o" AOItA iR[[ ^"' � (=0!) ]02-OI00 SHORT PLAT � � arµ� sT�� owN, rr o�n .iw Ha u�ro2e ,�u�„� ,�r e/is/os owo No.ia�a—oza cox a auv�i ��iir� e�' CIM(D.�Y fCALL fM[IT mo� uroM W5N NTS Z pr Z �►, � CITY OF RENTON ,� Planning/Building/PublicWorks Department Kathy Keolker-Wheeler, Mayor GreggZimmermanP.E.,Administrator OCtOber 7, ZOOS i ' � ' �, -� �: - � �� RECEIVED 7oe Pruss �� l 3 2005 Basic Ventures,Inc. 18211 —240`�Avenue SE BAIMA & HOLMBERG INC, Maple Valley, WA 98038 SUBJECT: HOQUTAM COURT SHORT PLAT REQUEST FOR MODI�'ICATION RIGHT-OF-WAY WIDTH REDUCTION Dear Mr.Pruss: The City of Renton received your request for the proposed right-of-way modification associated with the proposed six-lot, single-family residential short plat located at 810 Hoquiam Av �TE. The proposed modification requests to allow the proposed new ri$ht-of-way width of the street serving the new lots to be reduced to 26 feet and reducing the pavement width to 20 feet. A fiv� foot wide sidewalk will be provided along the north side of the new street, along with a standarcl curb and gutter section. Street lighting shall not be required for this section of new street. These improvements are identical to the modified public street standards being applied to the east for the rest of this short street section. These standards are similaz to those used for private streets - for a limited number of lots, with the exception-that the.street will be publicly owned and maintained, and the street shall include a curb, gutter and sidewalk. The Street Modification request is hereby approved subject to conditions listed below. The City can modify street improvements for new plats if there are practical difficulties in carrying out the provisions of the Street Improvement Ordinance: The Modification Procedures, as defined in Section 4-9-ZSOD, states the criteria for appioval by the Department Administrator. In order for a modification to be approved,the Department Administrator must, "find that a special individual reason makes the strict letter of this Ordinance impractical, that the modification is in confomuty with the intent and purpose of this Ordinance, and that such modification: (a) Will meet the objectives and safety, function, appearance, environmental protection and maintainability intended by this Ordinance, based upon sound engineering judgment; and (b} Will not be injurious to other property(s) in the vicinity; and (c) Conform to the intent and purpose of the Code; and (d) Can be shown to be justified and required for the use and situation intended; and I (e) Will not create adverse impacts to other properties in the vicinity." 1055 South Grady Way-Renton,Washington 98055 R E N T O N �This paper cantains 50°;recyded material,30%post consim�er AHEAD OF THE CURVE Joe Pruss/Hoquiam Court Short Plat October 7,2005 Page 2 of 3 Meets objectives and safety, function: The intent of public and emergency access and pedestrian amenities is met with the proposal as pavement width is retained to comply with fire codes and minimum access requirements. T'he proposed road cross-section will meet the minimum standards for an emergency response. Only the parcels on the north side of this street require access from this short street section,as the parcels to the south will front a new public street �. south of those parcels. When this short street section is comgleted, it will be a through street �. with two points of access. By the standards used for private streets, up to 12 parcels could be served from this.street�section if developed as a privat� street. In this case,the street will be � � dedicafed as a public sfreet, allowing for�arking_et�fo�cement by the Police Department and � �. street maintenance by the Public Wor�s�Vlaiqteriance�i�is�n. Not in�urious or adversel im aet ad'acei�t ro rties: A�jacen� roperties are not injured nor adversely unpacted as the pa ment�vidtli�and associated nght o��'ay dedication meet the requirements for vehicular,,petiestrian and emergency access �'� a i. . � .�:*;: . . . �_.' � r'. . . , - . . Conforms to the intent of the code: The Intent of provitiing for safe �cess for domestic, emergency and pedestrianacc�ss Yvill�ie met bv the.:��,�s�iosed�iesi�n,�vithout the additional , right-of=way, pavement vv�dth;'or streef lighting ` �� Justified and rec�uired for use and situafion intended: 'The zo�ing of this parcel is R-8, Single - Family. The modifications-as retj'uested allow the allowable dens�ty�vith lots that meet the various setbacks and access �ritema. The plat provides ihe minimtt�i necessary for full use for access, emergency and domestie.;a�d pedestrian amenities. ' ''- The Street Modification is aanroved subiect to the followiii�c�nditions: _..�� _ l. The street improvements required for the`approved preliminary plat (Aspen Woods Preliminary Plat)east of this site must be in place and dedicated to the City prior to the recording of this short plat. If these off-site improvements are not completed a temporary turnaround, approved by the Fire Department, will be accepted in place of the secondary access improvements. 2. No parking is allowed on either side of this street section. Sigriage will be required for No Parking along this new street section. 3. Full street improvements, per City standards, aie required along the frontage of the short plat on Hoquiam Av NE, including sidewalk,curb, gutter, associated drainage improvements, and street lighting. This decision to approve the proposed Street Modification is subject to a fourteen (14) day appeal period from the date of this letter. Any appeals of the administrative decision must be filed with thc City of Ren[on Hearing Examincr by 5:00 p.m., October 21, 2005. Joe Pruss/Hoquiam Court Short Plat October 7,2005 Page 3 of 3 Appeals must be filed in writing, together with the required$75.00 application fee, with: Hearing Examiner, City of Renton, 1055 South Grady Way, Rentori, WA 98055. Appeals to the Examiner are governed by City of Rentan Municipal Code Section 4-8-110. Additional information regarding the appeal process may be obtained from the Renton City Clerk's Office, (425)430-6510. If you have any questiflns, please contact Arneta Henninger, at (425)430 7298. I I Sincerely, . ; � : . , ..�+��7 - . . ' . '�� .� . �� , — � • l V (/'V � `�iJ� 11�'- ►`�vr��r�c�i �:- -,� : _, � ,' • . � � . Kayren Kittrick ` _� __`t x - , � � Development Engineering�iip�ervisor �� ,�. � ., .+ ,� . . _ Public Works Inspections�i Permits ', � -__t,. . - . � � - . . a 't°'.%i:e� ' � ' . . . . . . . . � . �' . ' . . . .. ...- cc: AmetaHenninger,Engine�hg S�ctaT�sC.��'"; �� +� � � Keri Weaver,Senior P,�anner : � � ¢ . _ Neil Watts,Developm�nt Services Director� a � ' ' Larry Rude,Fire Deputj�Clu�,�- � _._ - ' ' , �� . ;. �fi� , . . � �� ~"� . ,� �. .�if �> >A p""''° ri ,� .�- �. � . � : � . _; s �: .� . ... �� 'u � � �� " _. .M{ �� # - ' . 4�� s .. . . � . "'��B+�f:z`�'s"'��: , - , , ' � SECTION 3 OFFSITE ANALYSIS � Project Overview This project involves the development of a 0.95-acre parcel into six single-family , lots. The site is located on the east side of Hoquiam Avenue NE, at 810 Hoquiam ' Avenue NE. The site is about '/2 covered with an existing house, garage, sheds, I driveway and lawn, with the remainder covered with woods. The site slopes down to the east at about 1%to 8%. Per the SCS soil maps, the site is underlain with Alderwood Series sandy loam over glacial till. The recently constructed plats of Wedgewood and Aspen Woods are immediately adjacent to the north, south and east sides of the site. I Upstream Drainage I, Little if any drainage runs onto the site from offsite areas. Downstream Drainage Onsite runoff sheetflows at about 5% to 10% east drain through the wooded property to the east into the i2" CB/pipe Aspen Woods storm system (A). This discharges into a detention and water quality pond about 350' downstream from the sitc (B). At about 800' east of the site, the pond outfall drains into an adjacent wetland buffer (C)then into Honey Creek. Honey Creek flows northeast to well beyond '/e downstream from the site. There were no apparent drainage problems along this downstream drainageway. Proposed Drainage Controls Onsite flows will be picked up in a CB/pipe storm system and routed to an onsite, combination Level 2 detention vault and Basic Water Quality wetvault before being released into the Aspen Woods storm system. Frontage water quality control will be provided with Basic Water Quality dead storage in an oversized 72" CB. � � � � ' ' ` � ----� - , , --- * ;; ` I t . F; ;• ,� �. ,- :5. I .e • :,,: •� +r�*�{, E I�,..� a RO.. ' � w i f ! �!.. _----(�t` ` '• `�' #t 7� F �',', � ! � , . , �:. , � ... .r_..� -_ ' •, • � �.i� .�..i i�L.��,,a r I�;.rsce.� �i �l 44�� -1 t 1-.- �� . '_... _.u . . '. �-,/l��.i�trir�n-..-- ;: :`r: � i ` �..1... .� _.-- I Gl i.� ,�� - ; '��,-.._-:- `�4�f J\6Y��lrf � : _ .l .:��1[.sct� �i i 1� � � .A' - � i � �f '� .;'. . ,�///Y �� _ _ �«iii�' (x_ -+Ss . , , . , � r,�;t l_Li��i,! 4 (l� � � . 9� , E '` _ �' ' �.1 �-t i }� \ ( ,.. _ � � �._ :� - ti�((��,-: . 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I � . - '�77 � �� f � 1 ( �f t ' � �. i { l_._/^ ) i t�/ '/ /!I I 1 .1 .a I �: i ( ( � t . .� / t f!/ 7 7 ,�'� �) � � � � � '7 ; i i r (l�^'`',r- _ _('- }� i � i . ; ;� .. -.i - � " �� -o I.� � i i � 1� 1 J�I t � � I� 1 i 7 7 } Fi � �¢ { ~ . i � 1! i �1� � 7I � i �� j �. 4\t:. +l'. ` � �� ' � '�i t 4 .i F i ! f 7 . ;�•..- 1 � i # f V �t -�"� 1 �! ! +t �l � —f: T�_� �� ' f t , �' � ii� �` � �, � _ h_ -•- -' i ;� �1. � ��_ ' 'p � � � � � �;�t � � _: , / , � � � , j F�„^ _; . � 1 � ��; �-�� ; �� t� ; �� ;� � ,,,_ l�E.�:�;��jl�� f► .._�_ � � � �_ �cc<. �. ,1� .�� , ,��.�,-. ; : � , � ..___ �, � � < <. , � �� , l a:�� - ��" ��-�,� Z �;� . -~ � � � �� `-- �. \ E��- ;�_ , � :��.c � � � } � :� , ._�� . �.�1 � -r � ► r :� � � '� ��=C�� ,�_ - r , �, . . , � N D � ownstream Drainage Map i�� = Zso� � OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLE � Surface Water Design Manual� Core Requirement#2 Basin: �May Creek Subbasin Name: ;,- _ �• �-�'=�b �i�,G" Subbasin Number: SYmbol' prairla�� pr�lrl��e C��ipon�nt ; 51dp� ':bt�t�nco ! �xisti�e Potential '. � (Jbs�rvafions bf tiold,.in�p��tar ComponentlTyp�,; besCrlpt�nn , irom•site '�roblams Problbms ' resour�ejx�vinwor, �or rasidant , . _ ..:. . , ,. ,. ; . . Nam� artcl $ize `: ...;I -' < .;.?. dfsCfiAc �. . . - .. 7Yae;:sheetilavv,swa��;;: , << . ;� •` >; con�tdctlahs,undotcapacni';helkiinp, spe map . steam,chanriel,plpe, .. dretnege bnyin,vegetellon,covgr, 96 1/4 ft+l a 1�320 R overtopping,(tooding,hebk�t or nrgenlem lributdry erea,tlkdlhood oi probrem, pond; Slza:c�lerrmeter, ; depth;type af aeneat've erea,vnlume ; ; ; destniction,gcourin{�,bank sbughing; overtlaHpatMvttyre;potentlol:lr�pttcts: : ' surfece aree !` ..i' , > ;: < r>: edlmentatlon ln;.tslon othiet.crcMk�n 6 2 0 - 3 shee ° � 4 , none � �� t �s 5 — � NaNIL N� co�,1lk�Ii I �Iv � N 5 � MONI�- ��Gv rd�r�- � c u. 35 � ' � , i i • L1Tnble.doc 11/2/92 i -� � � � � SECTION 4 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN „� t,� � 3 -- � 7�v BAIMA & HOLMBERG� INC. SHEEfNO. OF 100 Front Steet South � ` ISSAQUAH, WASHINGTON 98027-3817 CALCUL4TEDBY T� onr� (425) 392-0250 FAX (425) 391-3055 CHECKED BY DATE SCALE _;_ ' . �j�(�-tNt (Jl1�-�n-- �I� S ! � Il� .__ r /�� __ ��"M!�� ': N r � �� G•J � �i'� i ��!JI"�`-'# Qr C�,J� ' ' /'S�l�� iv7�l-u l�. ' 'C � : �w��Ilt> ?3 _ _....... _ r , _ ... _ �' t r a�� _ __ ; . __ _._ �x. ��D � �Q� s _ ° : : _ _ . _ _ : �,� = _ ZgQO�� ; t- Z/�7c� 5F. _ _ .. , ' �-fDf1s�� A�l��z` �n t�i��r�a� _ _. :_ , ` ; � S��5' �_ _ _ i . , __. _. . � � = D� ( � ;�} c,, � : . ._ _ _ _ � _ ;__ . _ _ . ' t� - (� ��p ff��u/�J�. C N = '_ 8� - . � `- . : _._.: � � 3 ' _ �(�Z = D •`�� c. 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TYPE-ZA DISTRIBUTION **********�********` ********* 100-YEAR 24-HOUR STORM **** 3. 90" TOTAL PRECIP. **~****** ---------------------------------------------------------------------- DATA PRINT-OUT: F.R�fi(ACRES) PERVIOUS IMPER�IO�S TC(MINUTES) A CN A CN 1 .0 . 9 83.0 . 1 98 .0 38 .6 � �.-.f:-Q(CFS) T-PEAK(HRS) VOL(CU-FT) , . 37 �' , g3 8555 Developed Conditions SBUH Peaks --------------------------------------------------------------------- "'***************** S.C.S. TYPE-lA DISTRIBUTION ******************** �******* 100-YEAR 24-HOUR STORM **** 3.90" TOTAL PRECIP. ********* AREA(ACRES) PERVIOUS IMPERVIOUS TC(MINUTES) A CN A CN 1.0 .2 86.0 .8 98.0 6.3 PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT) .89 7. 67 12295 04ioo = 0 . 89 — 0 . 37 = 0 . 52 cfs .� /.G��-a z � BAIMA & HOLMBERG, INC. SHEETNO. 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Time Series File: 1673d.t: Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------ Flow Rate Rank Time of Peak - - Peaks - - Rank Return Pror. (CFS) (CFS) Period 0.207 6 2/09/O1 2:00 0.912 1 100.00 0. 9"� 0.175 8 1/05/02 16:00 0.285 2 25.00 0. 9r 0.248 3 2/27/03 7:00 0.248 3 10.00 0. 90 0. 196 7 8/26/09 2:00 0.235 9 5.00 0.80 0.235 9 10/28/04 16:00 0.221 5 3.00 0. 6F 0.221 5 1/18/06 16:00 0.207 6 2.00 0.50� 0.285 2 10/26/06 0:00 0. 196 7 1.30 0.23" 0.412 1 1/09/08 6:00 0. 175 8 1 . 10 0 .09= ��:�Gte,. Feaks 0. _.�G � . '��C . _ _'��:� 6' Deep KCRTS Level 2 Vault R:e`e-�`io�i��ter.tic�: Fa��iit1 Type cf Facility: Cetention Vault Facility Length: 84.00 f� Facility Width: 21.00 f� Facility Area: 1764 . s�. ft Effective Storage Depth: 6.00 ft Stage 0 Elevation: 460.80 ft Storage Volume: 10564. cu. ft Riser Head: 6.00 ft Riser Diameter: 12.00 inches Number of orifices: 2 Full Head Pipe Orifice # Height Diameter Discharge Diame`er (ft) (in) (CFS) (ial 1 0.00 0.69 � 0.031 2 4 .00 1. 13- 0.049 4 . 0 Top Notch Weir: Non� �ll'�f10�; �,3��_^.Q r'.]'_"`,�. r7C:12 ,.�age ::le�.,atlor_ Sto�a�e C�s�har�� Fe_�r.�;,r_--_ (ft) (ft} (cu. ft) (ac-ft) (cfs) (cfs; 0.00 460.80 0. 0.000 0.000 0.00 0.01 460.81 18. 0.000 0.002 0.0� 0.02 960.82 35. 0.001 0.002 0.0; 0.03 460.83 53. 0.001 0.002 O.00 0.04 460.84 71. 0.002 0.003 O.00 0.05 460.85 88. 0.002 0.003 O.00 0.06 460.86 106. 0.002 0.003 O.00 0.16 460. 96 282. 0.006 0.005 O.00 0.26 461.06 459. 0.011 0.007 O.CG 0.36 461.16 635. 0.015 0.008 O.00 0.46 961.26 811. 0.019 0.009 O.00 0.56 461.36 988. 0.023 0.010 0.0: 0.66 461.46 1164. 0.027 0.010 O.G' 0.76 461.56 1341. 0.031 0.011 O.G: 0.86 461. 66 1517. 0.035 0.012 O.G, 0.96 461.76 1693. 0.039 0.013 O.OG 1.06 461.86 1870. 0.043 0.013 0.00 1.16 461. 96 2046. 0.047 0.014 0.00 1.26 462.06 2223. 0. 051 0.014 0.00 1.36 462. 16 2399. 0.055 0.015 0.00 1.46 462.26 2575. 0.059 0.016 0.00 1.56 962.36 2752. 0.063 0.016 0.00 1. 66 462.46 2928. 0.067 0.017 0.00 1.76 462.56 3105. 0.071 0.017 0.00 1.86 462.66 3281. 0.075 0.018 0.00 1.96 462.76 3957. 0.079 0.018 0.00 2.06 462.86 3634 . 0.083 0.018 0.00 2. 16 962.96 3810. 0.087 0.019 0.00 2.26 463.06 3987. 0.092 0.019 0.00 2.36 463.16 4163. 0.096 0.020 0.00 e�; � 2.46 463.26 4339. 0. 100 0.020 0.00 2.56 463.36 4516. 0. 104 0.021 0.00 2. 66 463.46 4692. 0.108 0.021 0.00 2.76 463.56 4869. 0.112 0.021 0.00 2.86 463.66 5045. 0.116 0.022 0.00 2.96 463.76 5221. 0.120 0.022 0.00 3. 06 463.86 5398. 0.124 0.022 0.00 3.16 463. 96 5574. 0.128 0.023 0.00 3.26 464 .06 5751. 0. 132 0.023 0.00 3.36 464 . 16 5927. 0. 136 0.024 0.00 3.46 464 .26 6103. 0. 140 0.029 0.00 3.56 464 .36 6280. 0. 149 0.024 0.00 3. 66 464 .46 6456. 0. 148 0. 025 0.00 3.76 464 .56 6633. 0. 152 0.025 0.00 3.86 464.66 6809. 0.156 0.025 0.00 3. 96 464.76 6985. 0.160 0.026 0.00 4 .00 464.80 7056. 0. 162 0.026 0.00 4 .01 464.81 7074. 0. 162 0.026 0.00 4.02 464.82 7091. 0. 163 0.027 0.00 4.04 464.84 7127. 0. 164 0.028 0.00 4.05 464 .85 7144. 0. 164 0.030 0.00 4 .06 464 .86 7162. 0.164 0.032 0.00 4.07 969 .87 7180. 0.165 0.035 0.00 4.08 464.88 7197. 0. 165 0.036 0.00 4. 09 469 .89 7215. 0. 166 0.036 0.00 4.19 469 . 99 7391. 0.170 0.041 0.00 � 9 .29 465.Q9 7568. 0. 174 0.045 0.00 4 .39 465. 19 7744. 0. 178 0.048 0.00 4 .49 465.29 7920. 0. 182 0.051 0.00 4 .59 465.39 8097 . 0.186 0.054 0.00 4 . 69 965.99 8273. 0.190 0.056 0.00 ! 4 .79 965.59 8950. 0.194 0.059 0.00 i 4 .89 465.69 8626. 0.198 0.061 0.00 4. 99 465.79 8802. 0.202 0.063 0. 00 5.09 465.89 8979. 0.206 0.065 0. 00 5.19 465.99 9155. 0.210 0.067 0.00 5.29 466.09 9332. 0.214 0.069 0.00 '� 5.39 966.19 9508. 0.218 0.070 0.00 5.49 466.29 9684. 0.222 0.072 0.00 5.59 466.39 9861. 0.226 0.074 0.00 5. 69 466.49 10037. 0.230 0.075 0.00 5.79 466.59 10214. 0.234 0.077 0.00 5.89 466. 69 10390. 0.239 0.078 0.00 5.99 466.79 10566. 0.243 0.080 0.00 6.00 466. 80 10584 . 0.293 0.080 0.00 6.10 966.90 10760. 0.297 0.389 0.00 6.20 467.00 10937. 0.251 0.954 0.00 6.30 467.10 11113. 0.255 1. 680 0.00 6.40 467.20 11290. 0.259 2.480 0.00 6.50 467.30 11466. 0.263 2.760 0.00 6.60 467.40 11642. 0.267 3.020 0.00 6.70 467.50 11819. 0.271 3.250 0.00 6.80 467. 60 11995. 0.275 3.470 0.00 6. 90 967.70 12172. 0_279 3. 680 0.00 7.00 967.80 12348 . 0.283 3.880 0.00 7.10 967. 90 12524 . 0.288 4 .060 0.00 7 .20 468 .00 12701 . 0. 292 4 . 240 O. CO 7.30 968. i0 12877. 0.296 4 . 410 O. GO 7.40 468.20 13054. 0.300 9 . 570 0.00 7.50 468.30 13230. 0.304 4.730 0.00 7. 60 468.40 13406. 0.308 4.880 0.00 7.70 468.50 13583. 0.312 5.030 0.00 Hyd Inflow Outflow Peak Storage Target Calc Stage Elev (Cu-Ft) (Ac-Ft) 1 0.41 ******* 0.25 6.06 466.86 10689 . 0. 24� 2 0.21 ******* 0.08 5.82 466.62 10275. 0.236 3 0.21 0.08 0.07 5.34 966. 19 9423. 0.216 10-yr 4 0.22 ******* O.C6 4 .75 465.55 8385. 0. 192 5 0.25 ******* 0.05 4 .53 465.33 7997. 0. 189 6 0. 13 0.05 0.02 3.69 464 .44 6418. 0. 197 2-yr 7 0.17 ******* 0.02 2.73 463.53 4817. 0. 111 8 0.20 ******* 0.02 2.93 463.23 4285. 0.098 ---------------------------------- Route Time Series through Facility Inflow Time Series File:1673d.tsf Outflow Time Series File:rdout Inflow/Outflow Analysis Peak Inflow Discharge: 0.412 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: 0.255 CFS at 10:00 on Jan 9 in Year 8 Peak Reservoir Stage: 6.06 Ft Peak Reservoir Elev: 466.86 Ft � Peak Reservoir Storage: 10684. Cu-Ft . 0.295 Ac-Ft Flow Frequenc, -^�' �~ Time Series File:rdou� Project Location:Sea-1' ---Annual Peak Flow Rai_��--- -----r'ic;.: t'requei:c1 �riulYs�s----- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Pro� (CFS) (CFS) (ft) Period 0.077 2 2/09/O1 20:00 0.255 6.06 1 100.00 0. 99 0.021 7 12/28/O1 18:00 0.077 5.82 2 25.00 0. 96(` 0.052 5 3/06/03 22:00 0.070 5.34 3 10.00 0.9G( 0.020 8 8/26/04 6:00 0.058 4 .75 9 5.00 0. 80�:i 0.025 6 1/05/05 16:00 0.052 4.53 5 3.00 0. 66 0.058 4 1/18/06 22:00 0.025 3. 64 6 2.00 0.50: 0.070 3 11/24/06 7:00 0.021 2.73 7 1. 30 0.23] 0.255 1 1/09/08 10:00 0.020 2.43 8 1. 10 0.091 Computed Peaks 0. 196 6.04 50. 00 0 . 98C Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence Frobability CFS $ $ $ 0.001 37732 61.533 61.533 38.467 0.385E+00 0.003 4899 7.989 69.522 30.978 0.305E+00 0.005 9291 6.998 76.520 23.980 0.235E+00 0.008 3142 5.124 81.694 18 .356 0.184E+00 0.010 3362 5.483 87.127 12.873 0.129E+00 0.012 2982 4 .863 91. 990 8.010 0.801E-01 � 0.014 1935 3.156 95.145 4 .855 0.985E-01 C.016 805 i.313 96.458 3.�42 0.354E-01 0.018 917 1.495 97. 953 2.047 0.205E-G1 0.021 429 0.700 98. 653 1.347 0.135E-01 0.023 387 0. 631 99.284 0.716 0.716E-02 0.025 236 0.385 99. 669 0. 331 0.331E-02 0.027 78 0.127 99.796 0.209 0.204E-02 0.029 7 0.011 99.808 0.192 0. 192E-02 0.031 1 0.002 99.809 0. 191 0. 191E-02 0.033 0 0.000 99.809 0. 191 0.191E-02 0.036 2 0.003 99.812 0.188 0. 188E-02 0.038 6 0.010 99.822 0. 178 0. 178E-02 0.040 8 0.013 99.835 0. 165 0. 165E-02 0.092 7 0.011 99.897 0.153 0.153E-02 0.094 8 0.013 99. 860 0.140 0. 140E-02 0.096 11 0.018 99.878 0. 122 0. 122E-02 0.048 9 0.015 99.892 0. 108 0.108E-02 0.051 8 0.013 99. 905 0.095 0. 946E-03 0.053 12 0.020 99. 925 0.075 0.750E-03 0.055 6 0.010 99.935 0.065 0. 652E-03 0.057 5 0.008 99. 943 0.057 a.571E-03 0.059 5 0.008 99. 951 0.049 0.489E-03 0.061 4 0.007 99.958 0.042 0.429E-03 0.063 3 0.005 99. 962 0.038 0.375E-03 0.066 3 0.005 99. 967 0.033 0.326E-03 0.068 4 0.007 99.974 0.026 0.261E-03 0.070 6 0.010 99. 984 0.016 0.163E-03 0.072 2 0.003 99. 987 0.013 0.130E-03 0. 074 3 0.005 99.992 0.008 0.815E-04 0. 076 2 0.003 99. 995 0.005 0.489E-04 Discharge Volume Discharge Volume from Time Series rdout.tsf between 10/O1/00 00:00 and 10/30/00 23:59 16984 . Cu-Ft or 0.390 Ac-Ft in 30.0 days Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence Probability CFS g � � 0.023 60869 99.265 99.265 0.735 0.735E-02 0.025 303 0.494 99.759 0.241 0.241E-02 0.028 26 0.092 99.801 0. 199 0. 199E-02 0.031 5 0.008 99.809 0.191 0. 191E-02 0.033 0 0.000 99.809 0. 191 0.191E-02 0.036 6 0.010 99.819 0. 181 0.181E-02 0.039 5 0.008 99.827 0. 173 0.173E-02 0.042 9 0.015 99.842 0. 158 0.158E-02 0.094 11 0.018 99.860 0. 140 0. 140E-02 , 0.097 16 0.026 99.886 0. 114 0. 114E-02 0.050 9 0.015 99.901 0.099 0.995E-03 0.053 14 0.023 99.923 0.077 0.766E-03 0.055 8 0.013 99.936 0.069 0. 636E-03 0.058 6 0.010 99.946 0.059 0.538E-03 0.061 6 0.010 99. 956 0.044 0. 440E-03 0.063 4 0.007 99.962 0.038 0.375E-03 0.066 4 0.007 99.969 0.031 0.310E-03 0.069 6 0.010 99. 979 0.021 0.212E-03 � 0.072 4 0.007 99. 985 0.015 0.147E-03 0.074 4 0.007 99.992 0.008 0.815E-04 0.077 3 0.005 99.997 0.003 0.326E-04 � 0.080 2 0.003 100.000 0.000 O.O00E+00 , 0.083 0 0.000 100.000 0.000 O.O00E+00 i 0.085 0 0.000 100.000 0.000 O.00OE+OG 0.088 0 0.000 100.000 0.000 O.00OE+OG 0.091 0 0.000 100.000 0.000 O.O00E+00 0.093 0 0.000 100.000 0.000 O.O00E+00 0.096 0 0.000 100.000 0.000 O.O00E+00 0.099 0 0.000 100.000 0.000 O.O00E+00 0.102 0 0.000 100.000 0.000 O.O00E+00 0.104 0 0.000 100.000 0.000 O.O00E+00 0.107 0 0.000 100.000 0.000 O.O00E+00 0.110 0 0.000 100.000 0.000 O.O00E+00 0.113 0 0.000 100.000 0.000 O.O00E+00 0.115 0 0.000 100.000 0.000 O.O00E+00 �N �f n�� s�� r�f Duration Comparison Anaylsis C `O �v� ` � Base File: 1673u.tsf ��G�T rtW1 � 5 �� s New File: rdout.tsf �_� Cutoff Units: Discharge in CFS -----Fraction of Time----- ---------Check of Tolerance------- Cutoff Base New $Change Probability Base New �Change 0.023 I 0. 63E-02 0.55E-02 -11.7 � 0. 63E-02 0.023 0.023 -1.6 0.028 I 0.45E-02 0.20E-02 -56.8 I 0.45E-02 0.028 0.024 -15.8 0.033 I 0.31E-02 0. 19E-02 -38.7 � 0.31E-02 0.033 0.025 -25.3 0.038 I 0.20E-02 0. 18E-02 -12.9 I 0.20E-02 0.038 0.027 -29.9 0.043 I 0. 14E-02 0. 15E-02 10.8 I 0. 14E-02 0.043 0.045 3.6 0.048 I O. 10E-02 0.11E-02 9 .8 I O.10E-02 0.098 0.049 1.. 9 0.059 � 0.73E-03 0.72E-03 -2.2 I 0.73E-03 0.054 0.053 -1.3 0.059 I 0.55E-03 0.51E-03 -8.8 � 0.55E-03 0.059 0.058 -1.3 0.064 � 0.31E-03 0.38E-03 21. 1 � 0.31E-03 0.064 0.066 4 .2 0.069 I 0.20E-03 0.23E-03 16.7 I 0.20E-03 0.069 0.069 1. 1 0.074 � 0.98E-04 0. 11E-03 16.7 I 0.98E-04 0.074 0.074 0. 6 Maximum positive excursion = 0.009 cfs ( 5.80) �- � a°la oJ� occurrinq at 0.070 cfs on the Base Data:1673u.tsf and at 0.074 cfs on the New Data:rdout.tsf Maximum negative excursion = 0.012 cfs (-31. 6°s) occurring at 0.038 cfs on the Base Data: 1673u.tsf and at 0.026 cfs on the New Data:rdout.tsf .� ��, �� o� ; ��-`�c�� , � , � � ! ;� , 1 i ��i_�� O— � ' f�GU�.dU�` v target.dur ♦ � 0 0 co 0 0 (A o � o N o I � � o s U c,� � O � � 00 N O O � O O O �O 10 �5 10 -4 10 �3 10 -2 10 -� 10° Probability Exceedence ��d►� c v� u �s ; � �� r SECTION 5 CONVEYANCE SYSTEM ANALYSIS AND DESIGN JOB BAIMA & HOLMBERG, INC. SHEETNO. OF 100 Front Steet South ISSAQUAH, WASHINGTON 98027-3817 CALCULATEDBY on� (425) 392-0250 FAX (425) 3913055 CHECKED BY DATE SCALE . .,........_...._.. . . .,. . . .�._ ._._. ,.__.. - ....._. �. . ; ' _. _ . . ,. , . ... : � : ti�'��v�`� _ . �4-G� _. . �__.._._. _ : __ ___ ; . . __ __. _ - .-.- - .. _ _ . .__ ;. _ _ � : _ ... .. _ .. . : _ . , � _. :.. _ . . . -� _ _ _ _ _ _ � : _ . _ ._ ;_.__..�.---._ .� ._ . __t��_r--.. p_-8��'s :- .. �� S�c. :� _ � . � _ __.._.�._._..__.__ __ _ _ _ � _ � � - . ,_ ` .-_ IZ_ _ . �� _ ; �._ __�151_�'k,' _ 1 NL �" :.�N __ �- ' It�9r��'��}' _ .. ._..---.:_ .__ -- _ _ : _ _ : _ _ 1�"GI � '- �. � G�5 '_ --- � . _._..'.__......_:.._.._._.�---- ... _.. _ _ __ ....---..-- . - - - . .;. : . 9 : . - _ _ r :_ ��. : : : ° : : : : � � ...... .. .. . . : ��.,��,�,��, 4.3.1 CULVERTS-METHODS OF ANALYSIS FIGURE 4.3.1.B HEADVVATER DEPTH FOR SMOOTH INTERIOR PIPE CULVERTS WITH INLET CONTROL 180 10,000 �sg g�ppp EXAMPLE �1� �2� �3� ENTRANCE TYPE s. 156 6��0 D=42 inches (3.o teet)• 6. 5,000 �=�Zocts 5 SQUARE EDGEWITH 144 HEADWALL 6. 5. 4,000 HW HW 132 � ��t� 4. 3,000 ��) 2.s a.e 5' 4. 120 �2) 2.t �.� I I � 2,�0 (3) 2.2 7.7 4. � � 108 3. 3. •D in icet •+ gs 3. . PLAN �� 1,000 GROOVE END WITH 800 __..,.� __y HEADWALL 84 s� / 2. 2- �yYi / . 500 � 2. � : I. ._. 72 4� � p^ t � � = 300 �.�,Pj/ = 1.5 1.5 ' .�Jf Z gp V 200 �/ W 1.5 ' ` PLAN �2� - ? � W GROOVE END � 54 � � Q PROJECTING �F- �IL �� -p 48 / ¢ $O z . ♦ U 42 V 60 W 1.0 1.0 � �� O Q 50 HW SCALE ENTYANCE � 1.0 i� I 40 p P E � � w .9 9 FW-� � 30 (1) Square edg ith Q �� headw � '9 a 20 (2) G�oo end with W � � sadwall = •S .8 (3) Groove end 'a 27 projecting �� .7 ,7_ 24 8 .7 s o use scale (2) or(3) project 21 5 horizontally to scale (1), then 4 use stroight inclined line through D and � scales, or reversa as •s .6 illustrated. ,s �$ 2 15 � .5 �� .5 .5 1.0 �2 � �/ 1VJV� 1998 Surface VVater Desi�n h1anual 9/1/98 4-43 SECTION 6 I SPECIAL REPORTS AND STUDIES � C/1 r � H � O W� U � r� � H O I SECTION 8 ESC ANALYSIS AND DESIGN � JOB BAIMA & HOLMBERG, INC. SFiEETNO. OF 100 Front Steet South ISSAQUAH, WASHINGTON 98027-3817 ��W��BY DATE (425) 392-0250 FAX (425) 391-3055 CHECKED 8Y DATE SCALE . .�._. _�.__.._;......_ /'' ....... ... .. . .__ .. --"- --'-' -----.._.- '-- - .. _.. .._..._i__ ._..i. . .:.�� F �-�. . _. __ :�..� ...._. ... _ _...... _... ---- ._. _ .. __._ . _.. �=� _ � �c N ..;---.._,.._._. : _ _ _ _ : � � z : . �� 4-�� __ =_ _ I ��c., --._ ..._. ._..: :_ .-_-. .. } . ..:..._._._._... _._�1 N�G�•U.l��'_�v�-��. _; _. __... _. _ i ' ; , ._ ._>_..._.. - -..:...... _. _ . . .., ;. _ _ _ . . . : , ' :.. . -�- U5 i� ',�7,�� r� r�,�.7- `j�f�.'�' ; _ . : _ � _._ ,.._._.._ .__ : _ _ _ ___: ._... _ � �, _��: � _ �� - �� ,� � � � _ ___. . µ _ _ _ _ _ _ : ` - �� 5�- �3D`x 30 ' . __ .. . v-� -� : --..:......v....._....;.... ` � . .. _ v �! �/�c..�-Tp c��- . ..:_ . :__ ' z�� ' _ C�_ l,�s � T� ' : : : ' - - -- - -.... - - -- -�- -. ._ __. __ � ��,��.,� 2-year Developed Conditions SBUH Peak ---------------------------------------------------------------------- ******************** S.C.S. TYPE-lA DISTRIBUTION ******************** ********* 2-YEAR 24-HOUR STORM **** 2.00" TOTAL PRECIP. ********* ---------------------------------------------------------------------- DATA PRINT-OUT: AREA(ACRES) PERVIOUS IMPERVIOUS TC(MINUTES) A CN A CN 1.0 .2 86.0 .8 98.0 6.3 ,� I PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT) �i .41 7. 67 5668 ' l F , �, � Y..q � � �� .. �: i i:.. � I � _��'_-r� � . �" . �:.;..>.. , '� � . _, _�:�.._l' . . � I _ J � 1 � ; f�1 3 I { i SECTION 9 BOND QUANTITIES, FACILITY S ES, AND DECLARATION OF COVENANT I �I KIhG COUNTY, �VASHINGTON, SURFACE �VATER DESIGN MANUAL STORMWATEIt FACILITY SU14�VIARY SHEET - Development ��/� �'WL �ir Date - _ Location �tl� f��(/l A�w� /9'(�� lU� ENGINEER DEVELOPER Name ,N Name �N �S Firm 1l� Firm Address ( Address 'Z 2 �a E"z W Z 3� Phone � 2 - Z � Phone Developed Site: Acres 6. � 7 Number of lots_� Number of detention facilities on site: Number of infiltration facilities on site: ponds ponds �_vaults vaults . tanks ' tanks I Flow con�ol provided in regional facility(b ve location) ' No flow control required Exemption number j . Downstream Drainaoe Basins �, Immediate Ma'or Basin � B asin A Basin B — Basin C Basin D Number&type of water quality facilities on site: biofiltration swale(rea lar/wed or sand filter(basic or large?) � . continuous inflow?) sand filter,lineaz(basic or large?) combined detention/WQ pond sand filter vault(basic or large?) (WQ portion basic or larDe?) . �_combined detention/wetvault stormwa[er wedand � compost filter wetpond(basic or large?_) filter sQip wetvault flow dispersion farm management plan landscape managemen[plan oiUwater separator(baffle or coalescing pla[e?) catch basin inseru:Manufacturer pre-settlin�pond pre-settlin�structure:Manufacturer flow-splitter catctibasin DESIGN INFORMATION � INDIVZDUAL BASIN A ' B C D �Vater Qualit desibn flow VS'ater Qualit treated volume or w�et ond Vr 1995 Surfacc Watcr Desian Manual S 1 KING COUNTY, WASHINGT�N, SURFACE �VATER DESIGN 2�4ANL3AL - - DESIGN TOTAL INDIVIDUAL BASIN - INFORMATION, cont'd � Drainage basin(s) A B C D Onsite area �, ^ - , Offsite area , �t T e of Storaae Facilit V L Live Stora�e Volume Predevelo ed Runoff Rate 2- ear . 5 5 10- ear . 9' C S 100- ear . ( G S Develo ed runoff rate 2- ear 'q" 5 � 10- ear 100- ear • T e of restrictor . Size of orifice/resh-iction No. 1 No.2 t tt No.3 No.4 FLOW CONTROL&WATER QUALITY FACILITY SLJNIIv1ARY SHEEf SKETCH All detention,infil�ation and water quality facilities must include a sketch per the followino criteria: - 1. Heading for the drawinas should be located at the top of the sketch(top right-hand corner). - The heading should contain: _ • North arrow(point up or to left) "• D9� - • Elat name or short plat number. •Address(nearest) • Date dravm(or updated) •Thomas Brothers paae,grid number 2. Label CBs and MHs with the plan and profile desi�nation. Label the control structure in writing or abbreviate with C.S. Indicate which structures provide spill control. _ ' ' 3. Pipes--indicate: • '_ ' Pipe size Pipe len�th ;- Flow direcdon ' Use s single heavyweight line � 4. Tanks—use a double,heavyweight line and indicate size(diameter) 5. Access roads � • Outline the limits of the road . • Fill the outline with dots if the road is gravel. Label in�vriting if another surface. 6. Other Standard Symbols: • Bollards:� �@ O ta n �[ I� • Rip rap o00000 000000 Fences --x---x---x---x---x---x--- • Ditches —D---�D—_->-D---}-D ' 7. Label trash racks in writing. I 8. Label zll streets with the actual street sian desi�nation. If you don't know the actual street name,consult the plat map. 9. Include easemenu and lot lines or trac[limits when possibie. 10. Airange ali the labelin�or writing to read from left to right or from bottom to top with reference to a properly oriented headinb. 11. Indicate drive�vays or features that may impact access,maintenance or replacement. 9!1/9S 1998 Surface Water Desi�n Manual 2 84' ------------------------- --FINISHED GRADE � � I REMOVABLE BAFFLE � I � I W.S. O OVERFLOW ---- Sx10' REMOVABLE � 466_80 �___ �� I ZS GRATE W/ACCESS I I I 6' DEiENT10N STORACE 4.0'AVERACE WATER � I _ _ _ OUALITV STORACE „.I I �MIN„' '!—'_ IN:_ � � I —— ———————————————————— J 2t'—1 i'nVERAGE SEDIMENT STORACE DfPTH SECTION A—A —��v_`ae6.eo 6" PVC PERFORATED DRAIN N1TH DRAIN ROCK IE=461.25 ELEv DRAIN To�e,r, PLAN VIEW .464.8 N TS 1 1/B'0 ORIFICE�-- .-FRAMES, GRATES AND ROUND SOLID CObERS NOTES: MARKED 'DRAIN" W LOCKING BOLTS. TYP. �� ALL METAL PARTS MUST BE CORROSION RESISTANT. � � � STEEL PARTS MUST BE GAWANIZED AND ASPHALT . COATED (TREATMENT I OR BETTER). OVERFLOW FREEBOARD 2. PROVIOE WATER STOP AT ALL CAST-IN-PLACE . 12"RISER . (fi� MIN.) 9" MIN. CONSTRL1CilON JDINTS. COVER SHEAR CATE W/HANDLE-��., �� - SEE KCRS DNG. N0. 12" SD 2-026 -CONTROL STRUCTURE OUiLET -SEE DETAIL '_______ ' ' ' ' ' _ _ ' 0 1' SECTION OF PIPE ` � — —T�� -�— ATTACHED BY �� . � 8' DETENTION SHEAR GATE-�._ GASKET BANO TO �6" PVC PERFORATED DRAIN �� 2'MIN�� YdTH DRAIN ROCK _ �INV�458.80 n TOP EIEV= 481.80 STORAGE �� ALLOW REMOVAL �� INV=460.80 �E�461.0 ____—}F��TTbM �V�4�.�7___�___--�_ --___ y � l' ORAIN TO CB�y 1 �--_-_---��ry�___0 5$MIN. _ --- INV�460.80 72" SD ———————— — 6' PVC PERFORATED ORAIN 11/16" ORIFICE-' ST�. GALV. � WITH DRAIN ROCK 2'MIN LADDER OR STEPS 4' AVERAGE WATER �Ee467.25 �I 1'AVERAGE SEDIMENT - DRAIN TO C8�1 STORAGE DEPTH OUALITY STORAGE N O TE. SEE VAULT STRUCTURAL DRAWINCS ELEVATION CONTROL STRUCTURE DETAIL DETENTIONfWATER QUALITY VAULT N.T.S. N.T.S. SECTION 10 OPERATIONS AND MAINTENANCE 1��1ANUAL KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL KING COUNTY,WASHINGTON SURFACE WATER DESIGN MANUAL APPENDIX A MAINTENANCE REQUIREMENTS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES Section No. Subiect 1 Detention Ponds ! 2 Infiltration I 3 Closed Detention Systems I 4 Control StructureJ Flow Restrictor ; 5 Catch Basins �, 6 Debris Barriers 7 Energy Dissipaters 8 Fencing 9 Gates 10 Conveyance Systems 11 Grounds 12 Access Roads/Easements 13 Water Gluality Facilities A) Biofiltration Swale B) Filterstrips C) Wetponds D)Wetvaults E) Sand Filters F) Leaf Compost Filtars G) Infiltration Ponds 14 Oil Control Facilities A) OiU Water Separators B)Catch Basin Inserts 9/1/98 KING COL"I�T�', «.�SHINGTOV, SURFACE ��'ATER DESIGN h1ANUAL i APPENDIX A '� MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES ' NO. 1 - DETENTION PONDS �� Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed I General Trash$Debris Any trash and debris which exceed 1 cubic foot Trash and debris cieared from site. per 1,000 square feet(this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Poisonous Vegetation Any poisonous or nuisance vegetation which No danger of poisonous vegetation may constitute a hazard to County personnel or where County personnel or the the public. public might normally be. • (Coordination with Seattle-King County Health Departrnent) Pollution Oil,gasoline,or other contaminants of one No contaminants present other than gallon or more or any amount found that could: a surface film. (Coordination witfi 1)cause damage to plant,a�imal,or marine tife; Seattie/King Counry Heatth 2)constitute a fire hazard;or 3)be flushed Deparbnent) downstream during rain storms. Unmowed Grassl If facil'ity is located in private residential area, When mowing is needed, Ground Cover mowing is needed when grass exceeds 18 grass/ground cover should be inches in height. In other areas,the general mowed to 2 inches in height. policy is to make the pond site match adjacent Mowing of selected higher use ground cover and terrain as long as there is no areas rather than the entire slope interference with the function of the faciliry. may be acceptable for some situations. Rodent Holes Any evidence of rodent holes if facility is acting Rodents destroyed and dam or as a dam or berm,or any evidence of water beRn repaired. (Coordination with piping through dam or berm via rodent holes. Seattle/King County Health Department) Insects When insects such as wasps and homets Insects destroyed or removed from interfere with maintenance activities. site. Tree Growth Tree growth does not allow maintenance access Trees do not hinder maintenance or interferes with maintenance activity(i.e.,slope activi6es. Selectively cultivate trees mowing,silt removal,vactoring,or equipment such as alders for firewood. movements). If trees are not interfering with access,leave trees alone. Side Slopes of Pond Erosion Eroded damage over 2 inches deep where Slopes should be stabilized by cause of damage is still present or where there using appropriate erosion control is potential for continued erosion. measure(s);e.g.,rodc reinforcement,planting of grass, compaction. Storage Area Sediment Accumulated sediment that exceeds 10°/of the Sediment cleaned out to designed designed pond depth. pond shape and depth;pond reseeded if necessary to control erasion. Pond Dikes 5ettlements Any part of dike which has settled 4 inches lower Dike should be buitt back to the than the design elevation. design elevation. Emergency Rock Missing Only one Iayer of rock exists above native soil in Replace rodcs to design standards. Overflow/Spillway area five square feet or larger,or any exposure of native soil at the top of out flow path of spillway. Rip-rap on inside slopes need not be replaced. 1998 Surface Water Design h•lanual 9/1/98 I a-i APPENDIX A MAINT'ENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO.2-INFlLTRATION Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed General Trash&Debris See'Ponds'Standard No. 1 See'Ponds'Standard No. 1 Poisonous Vegetation See'Ponds'Standard No.1 See'Ponds'Standard No. 1 Pollution See'Ponds'Standard No. 1 See'Ponds'Standard No. 1 Unmowed Grass/ See'Ponds'Standard No.1 See'Ponds'Standard No.1 Ground Cover Rodent Holes See'Ponds'Standard No.1 See'Ponds'Standard No. 1 Insects See'Ponds'Standard No.1 See'Ponds'Standard No.1 Storage Area Sediment A percola6on test pit or test of facility indicates Sediment is removed and/or facility facility is only working at 90%of its designed is deaned so Uiat infiltration system capabilities. If two inches or more sediment is works according to design. present,�emove. Sheet Cover(If Sheet cover is visible and has more that three Sheet cover repaired or replaced. Applicable) 1/4-inch holes in it Sump Filled with Any sediment and debris filling vault to 10%of Clean out sump to design depth. Sediment and Debris depth from sump bottom to bottom of outlet pipe (If Applicable) or obstructing flow into the connector pipe. RRer Bags Flled with Sedment Sediment and debris fill bag more than 1/2 full. Replace filter bag or redesign and Debris system. Rodc Filters Sediment and Debris By visual inspection,Gttie or no water flows Replace gravel in rock filter. through fifter during heavy rain storms. Side Slopes of Pond Erosio� See'Ponds'Standard No.1 See'Ponds'Standard No.1 Emergency Rock Missing See'Ponds'Standard No.1 Overtlow Spllway Settling Ponds and Sediment Remove when 6'or more. Vaults Note: Sediment accumula6on of more than 25 inches pei year may indicafe excessive erosion is ocacurring upstream ot the facility or that conveyance systems aie not being propedy maintained. The contributing drainage area should be checked for erosion problems or inadequate maintenance of conveyance systems it excessive sedimencation is noted in an inBltration facility. Check twice a year during firsi 2 years of operaSon;once a year thereaffer. Gean manholes✓catch basins,repair damaged inlets/outlets, dean frash racks. 9/1/98 1998 Surface Water Design Manual A-2 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 3-CLOSED DETENTION SYSTEMS(PIPES/TANKS) Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Storage Area Plugged Air Vents One-half of the cross section of a vent is blocked at Vents free of debris and any point with debris and sediment sediment Debris and Accumulated sediment depth exceeds 10%of the All sediment and debris Sediment diameter of the storage area for 7h length of storage removed from storage area. vault or any point depth exceeds 15%of diameter. Example:72-inch storage tank would require cleaning when sediment reaches depth of 7 inches for more than Yz length of tank. Joints Between Any crack allowing material to be transported into All joint between tank/pipe Tank/Pipe Section faciliry sections are sealed Tank Pipe Bent Any part of tank/pipe is bent out of shape more than Tank/pipe repaired or replaced Out of Shape 109'0 of iYs design shape to design. Mar�F►ole Cover Not in Place Cover is missing or only partially in place.Any open Manhole is dosed. manhole requires maintenance. Lodcing Mechanism cannot be opened by one maintenance Mechanism opens with proper Mechanism Not person with proper tools.Bolts into frame have less tools. Working than Yz inch of thread(may not apply to self-locking lids.) Cover Difficuft to One maintenance person cannot remove lid after Cover can be removed and Remove applying 801bs of lift. Intent is to keep cover from reinstalled by one maintenance sealing off access to maintenance. person. , Ladder Rungs King County Safery Office and/or maintenance person Ladder meets design standarcis Unsafe judges that ladder is unsafe due to missing rungs, atlows maiMenance person safe misalignment,rust,or cradcs. access. Catch Basins See'Catch Basins"Standards No.5 See"Catch Basins"Standards No.5 ;:� . '"�. : � � � ,� �;, i,� � ' � J M1� _:�i� 1998 Surface Water Desi�n Manual 9/1/98 A-3 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO.4-CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed General Trash and Debris Distance between debris build-up and bottom of All trash and debris removed. (Includes Sediment) orifice plate is less than 1-1/2 feet Structural Damage Structure is not securely attached to manhole wall Structure securely attached to and outlet pipe sWcture should support at least wall and outlet pipe. 1,000 Ibs of up or down pressure. Structure is not in upnght position(allow up to Structure in correct position. 10%from plumb). Connections to outlet pipe are not watertight and Connecoons to outlet p�ne are show signs of rust. water Ught;structure r�: i . c _ replaced and works as designed. My holes—other than designed holes—in the Structure has no holes oth - struchue. than designed holes. Cleanout Gate Damaged or Missing qeanout gate is not watertight or is missing. Gate is watertight and wortcs as designed. Gate cannot be moved up and down by one Gate moves up and down easily maintenance person. and is watertight. Chain leading to gate is missing or damaged. Chain is in pla��-an� worh.s as designed. Gate is rusted over 50%of its surface area. Gate is reFa�r..d c� r��=-c to meet design standares . Orifice Plate Damaged or Missing Corrtrd device is not working properiy due to Plate is in place and works as missing,out of place,or bent orifice plate. designed. Obstructions Any trash,debris,sediment,or vegetation Plate is free of all obstructions blocking the plate. and worics as designed. Overflow Pipe Obstructions Any trash or debris blocking(or having the Pipe is free of all obstructions potential of blocking)the overflow pipe. and works as designed. Manhole See"Closed Detention Systems"Standards No.3 See"Closed Detention Systems' Standards No.3 Catch Basin See"Catch Basins"Standards No.5 See'Catch Basins"Standards No.5 I 9/1195 1995 Surface A�'ater Desien 1�Sanual A-4 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 5-CATCH BASINS Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed General Trash&Debris Trash or debris of more than 1/2 cubic foot which is No Trash or debris located (Includes Sediment) located immediately in front of the catch basin immediately in front of catch opening or is blocking capacity of the basin by basin opening. more than 10% Trash or debris(in the basin)that exceeds 1/3 the No trash o�debris in the catch depth from the bottom of basin to invert the lowest basin. pipe into or out of the basin. Trash or debris in any inlet or ouUet pipe blocking In{et and ouUet pipes free of more than 1/3 of its height trash or debris. Dead animals or vegetation that could generate No dead animals or vegetation odors that could cause complaints or dangerous present within the catch basin. gases(e.g.,methane). DeposiLs of garbage exceeding 1 cubic foot in No condition present which volume would attract or support the breeding of insects or rodents. Structure Damage to Comer of frame extends more than 3/4 inch past Frame is even with curb. Frame and/or Top Slab curb face into the street(If applicable). ToQ slab has holes larger than 2 square inches or Top slab is free of holes and cracks widef than 1/4 inch(intent is to make s��e cracks. all material is running into basin). Frame not sitting flush on top slab,i.e.,separation Frame is sitting flush on top of more than 3/4 inch of the frame from the top slab. slab. Cracks in Basin Walls/ Cracks wider than 1!2 inch and longer than 3 feet, Basin replaced or repaired to Bottom any evidence of soil particles entering catch basin design standards. through cradcs,or maintenance person judges that structure is unsound. Cracks wider than 1/2 inch and longer than 1 foot No cracks more than 1/4 inch at the joint of any inleU outlet pipe or any evidence wide at the joint of inleUouUet of soil particles entering catch basin through pipe. cradcs. SedimenU Basin has settled more than 1 inch or has rotated Basin replaced or repaired to Misalignment more than 2 inches out of alignment design standards. 1998 Surface Water Design Manual 9/1l98 A-� � APPENDIX A MAINTENANCE STANDARDS FOR PRNATELY MAINTAINED DRAINAGE FACILITIES NO. 5-CATCH BASINS(COMINUED� ' Maintenance Defect Conditions When Maintenance is Needed Resutts Expected When Component Maintenance is pertormed Fire Hazard Presence of chemicals such as natural gas,oil and No flammable chemicals gasoline. present Vegetation Vegetation growing across and blocking more than No vegetation bbcking opening 10%of the basin opening. to basin. Vegetation growing in inleUoutlet pipe joi�ts that is No vegehtion or root growth more than six inches tall and less than six inches present apart. Pollution Nonflammable chemicals of more than 1/2 cubic foot No pollution present other than pe�three feet of basin length. surface film. Catch Basin Cover Cover Not in Place Cover is missing or only partialty in place.Any open Catch basin cover is closed catch basin requires maintenance. Locking Mechanism Mechanism cannot be opened by on maintenance Mechanism opens with proper Not Working person with proper tools.8olts into frame have less tools. than 1/2 inch of thread. Cover Difficult to One maintenance person cannot remove lid after Cover can be remo�ed by one Remove applying 80 Ibs.of lift;intent is keep cover from maintenance person. sealing off access to maintenance. Ladder Ladder Rungs Ladder is unsafe due to missing rungs,misalignment, Ladder meets design standards Unsafe rust,cracks,or sharp edges. and albws maintenance person safe access. Metal Grates Grate with opening wider than 7/8 inch. Grate opening meets design (If Applicable� standards. Trash and Debris Trash and debris that is blocking more than 209'0 of Grate free of trash and debris. grate surface. Damaged or Grate missing or broken member(s)of the grate. Grate is in place and meets Missing. design standards. NO.6 DEBRIS BARRIERS(E.G.,TRASH RACKS) Maintenance Defect Condition When Maintenance is Needed Resutts Expected When Components Maintenance is Pertormed. General Trash and Debris Trash or debris that is plugging more than 20�0 of Barrier Gear to receive capaaty the openings in the barrier. flow. Metal Damaged/Missing Bars are bent out of shape more than 3 inches. Bars in place with no bends more Bars. than 3/4 inch. Bars are missing o�entire bamer missing. Bars in place according to design. Bars are loose and rust is causing 50%deterioration Repair or replace barrier to to any part of barrier. design standards. 9/1/98 1995 Surface V4'ater Design Manual , A-6 __ ___ � APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITTES NO. 7- ENERGY DISSIPATERS � Maintenance Defect Conditions When Maintenance is Needed Results Expected When Components Maintenance is Performed. I Extemal: ' Rock Pad Missing or Moved Only one layer of rock exists above native soil in Replace rodcs to design Rock area five square feet or larger,or any e�osure of standards. native soil. Dispersion Trench Pipe Plugged with Accumulated sediment that exceeds 20%of the Pipe cleaned/flushed so that it li Sediment design depth. matches design. I Not Discharging Visual evidence of water discharging at Trench must be redesigned or Water Properiy concentrated points along trench(normal condition rebuilt to standards. is a`sheet flonr'of water along Vench).Intent is to prevent erosion damage. Perforations Over 1/2 of pertorations in pipe are plugged with Clean or replace perforated pipe. I Plugged. debris and sediment. I Water Flows Out Maintenance person observes water flowing out Facility must be rebuitt or ' Top of"Distributo�' during any storm less than ihe design stortn or its redesigned to standards. Catch Basin. causing or appears likety to cause damage. Receiving Area Water in receiving area is causing or has potential No danger of landslides. Over-Saturated of causing landslide pro6lems. � Intemal: ' Manhole/Chamber Wom or Damaged Structure d�ssipating flow deteriorates to 1/2 or Replace structure to design Post.Baffles,Side original size or any concentrated wom spot standards. of Chamber exceeding one square foot which would make structure unsound. Othe�Defects See"Catch Basins'Standard No.5 3ee"Catch Basins'Standard No. 5 J .,;; • � ' � -:�1. . �� I . . `{� � I 1998 Surface Water Design Manual 9/1/98 A-7 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATEL�'h4AINTAINED DRAI�IAGE FACILITTES NO. 8- FENCING Maintenance Defect Conditions When Maintenance is Needed Results Expected When Components Maintenance is Performed General Missing or Broken My defect in the fence that permits easy entry Parts in place to provide adequate Parts to a facility. security. Erosion Erosion more than 4 inches high and 12-18 No opening under the fence that inches wide permitting an opening under a exceeds 4 inches in height. fence. Wire Fences Damaged Parts Post out of plumb more than 6 inches. Post plumb to within 1-1/2 inches. Top rails bent more than 6 inches. Top rail free of bends greater than 1 inch. Any part of fence(inGuding post,top rails,and Fence is aligned and meets design fabric)more than 1 foot out of design alignment. standards. Missing or loose tension wire. Tension wire in place and holding fabnc. Missing or loose barbed wire that is sagging Barbed wire in place with less than more than 2-1/2 inches between posts. 3/4 inch sag between post. Extension artn missing,broken,or bent out of Extension arm in place with no shape more than 1 1/2 inches. bends larger than 3/4 inch. Deteriorated Paint or Part or parts that have a rusting or scaling Structurally adequate posts or Protective Coating condition that has affected structural adequacy. parts with a un'rform protective coating. _ Openings in Fabric Openings in fabric are such that an 8-;nrh- No openings in fabric. diameter ball could fit through. NO. 9- GATES MaintenanCe Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Pertormed General Damaged or Missing Missing gate or lodcing devices. Ga- � L ;.� { : - Members pIa.-_ Broken or missing hinges such that gate cannot Hin;�:�,- �ma�� _t� : ,.-__, , .. be easily opened and dosed by a maintenance working fre� : person. Gate is out of plumb more than 6 inches a : . : more than 1 foot out of design alignment. Missing stretcher bar,stretcher bands,an�: :.__. _:.�. place. Openings in Fabric See"Fencing"Standard No.8 See"F 9/1/98 1998 Surface Water Desi�n Manual A-8 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES N0. 10-CONVEYANCE SYSTEMS(PIPES & DITCHES) Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Pipes Sediment&Debris Accumulated sediment that exceeds 20%of the Pipe cleaned of all sediment diameter of the pipe. and debris. Vegetation Vegetation that reduces free moveme�t of water All vegetation removed so water through pipes. flows freely thraugh pipes. Damaged Protective coating is damaged;rust is causing Pipe repaired or replaced. more than 50%deterioration to any part of pipe. Any dent that decreases the cross section area of Pipe repaired or replaced. pipe by more than 20%. Open Ditches Trash&Debris Trash and debris exceeds 1 cubic foot per 1,000 Trash and debris cleared from square feet of ditch and slopes. ditches. Sediment Accumulated sediment that exceeds 20°h of the Ditch cleaned/Hushed of all design depth. sediment and debris so that it matches design. Vegetation Vegetation that reduces free movement of water Water flows freely through through ditches. ditches. Erosion Damage to See'Ponds"Standard No.1 See'Ponds"Standard No. 1 Stopes Rock Lining Out of Maintenance person can see native soil beneath Replace rocks to design Place or Missing(If the rock lining. standards. ApPlicable). Catch Basins See'Catch Basins:Standard No.5 See"Catch Basins"Standard r:u.s Debris Barriers See"Debris Barriers"Standard No.6 See"Debris Barriers'Standard (e.g..Trasr Rack) N��. 6 NO_ 11 - GROUNDS (LANDSCAPING) Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed � General Weeds Weeds growing in more than 20%of the landscaped Weeds present in less than 5% (IVonpoisonous) area(trees and shrubs only). of the landscaped area. Safety Hazard Any presence of poison ivy or other poisonous No poisonous vegetation vsgetation. present in landscaped area. Trash or Litter Paper,cans,bottles,totaling more than 1 cubic foot Area dear of litter. within a landscaped area(Vees and shrubs only)of 1,000 square feet Trees and Shn�bs Damaged Limbs or parts of Vees or shrubs that are split or Trees and shrubs with less than broken which affect more than 25°k of the total 5'/0 of total foliage with split or foliage of the tree or shrub. broken limbs. Trees or shrubs that have been blown down or Tree or shrub in place free of knocked over. injury. Trees or shrubs which are not adequately supported Tree or shrub in place and or are leaning over,causing exposure of the roots. adequatety supported;remove any dead or diseased Vees. 1998 S�rface Water Design Manual 9/1/98 A-9 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES N0. 12-ACCESS ROADS/EASEMENTS �' Maintenance Defect Condition When Rlaintenan�e is Neede� Results Ezpected When Component Maintenance is Pertormed General Trash and Debris Trash and debris exceeds 1 cubic foot per 1,000 Roadway f�ee of debris which square feet i.e.,trash and debris would fiil up could damage tires. one standards size garbage can. Blocked Roadway Debris which could damage vehicle tires(glass Foadway free of debris which I or metal). could damage tires. il Any obstruction which reduces dearance above Roadway overhead dear to i4 feet road surface to less than 14 feei high. Any obstruction restricting the access to a 10 to Obstruc0on removed to allow at 12 foot widtfi for a distance of more than 12 feet least a 12 foot access. � or any point resficting access to less than a 10 foot width. Road Surtace Settlement,Pothdes, When any surface defect exceeds 6 i�ches in Road surface unifoRnly smooth , Mush Spots,Ruts depth and 6 square feet in area.In general,any with no evidence of settlement, surface defect which hinders or prevents potholes,mush spots,or ruts. maintenance access. Vegetation in Road Weeds growing in the road surface that are Road surface free of weeds taller Surface more than 6 inches tall and less than 6 i�ches than 2 inches. tall and less ihan 6 inches apaR within a 400- � square foot area. Modutar Grid Buld-up of se�ment mildly contaminated with Removal of sediment and disposal Pavement petroleum hydrocarbons. in keeping with Health Departrnent I recommendations for mildly coniaminated soils or catch basin sediments. Shoulders and Erosion Damage Erosion within 1 foot of the roadway more than 8 Shoulder free of erosion and Ditches inches wide and 6 inches deep. matching the surrounding road. Weeds and Brush Weeds and brush exceed 1 S inches in height or Weeds and brush cut to 2 inches hinder maintenance aocess. in height or cleared in such a way as to allow maintenance access. 9/1/98 ]998 Surface Water Design Manual A-10 APPENDIX A h4AI\TENANCE STANDARDS FOR PRIVATELY b9AIN"I'AINED DRAINAGE FACILTI'IES NO. 13-WATER GIUALITY FACILITIES A.) Biofiltration Swale Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Pertormed BiofiRration swale Sediment Accumulation Sediment depth exceeds 2-inches No sediment deposits on grass on Grass Layer layer of the bio-swale,which would impede fiftration of runoff. Vegetation When the grass becomes excessively tall Vegetation is mowed or nuisance (greater than 10-inches);when nuisance weeds vegetation is eradicated,such that and other vegetation starts to take over. flow not impeded.Grass should be mowed to a height between 4 inches and 9 inches. Inlet Outtet Pipe InIeU outlet pipe clogged with sediment and/or No dogging or blockage in the inlet debris. and outlet piping. Trash and Debris Trash and debris accumulated in tfie bio-swale. Trash and debris removed from Accumulation bioswale. Erosion!Scouring Where the bio-swale has eroded or scoured Bioswale should be re-graded and the bottom due to flow channelization,or higher re-seeded to specification,to flows. eliminated channeled flow. Overseeded when bare spots are evident N0. 13-WATER QUALtTY FACILITIES (CONT)NUEDj B.) Grasslined Filter Strips Maintenance Defect Condition When Maintenance is Needed Results Expe;ted When Component Maintenance is Performed Filter Strip Sediment Accumulation Sediment depth exceeds 2 inches. No sediment deposits on grass on Grass Layer layer of the filter strip,which would impede fittration runoff. Vegetation When the grass becomes excessively tall Vegetation is mowed or nuisance (greaterthan 10-inches);when nuisance weeds vegetation is eradicated,such that and other vegeta6on starts to take over. flow not impeded.Grass should be mowed to a height between 4 inches and 9 inches. Trash and Debris Trash and debris accumulated on the fiRer Trash and Debris removed from Accumulation strip. filter. Erosion/Scouring Where the filter strip has eroded or scoured Strip should be re-graded and re- due to flow channelization,or higher flows. seeded specification,to eliminate channeled flow.Overseeded when bare spots are evident. V-Notch Pipe Weir When the V-Notch pipe becomes damaged or Cleaned and properly functioning clogged with sedimenU debris. weir,such that flows uniformly spread. 1998 Surface Water Design Manual 9!1/98 I A-11 I � APPENDIX A MAINTENANCE STANDARDS FOR PRNATELY MAINTAINED DRAINAGE FACILITIES C.)Wetponds Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Pertormed Wetpond Vegetation Vegetation such as grass and weeds need to be Vegetation should be mowed to mowed when it starts to impede aesthetics of pond. 4 to 5 inches in height. Trees Mowing is ge�erally required when height exceeds and bushes should be removed 18-inches.Mowed vegeta6on should be removed where they are interfering with from areas where it coutd enter the pond,either pond maintenance activities. when the pond level rises,or by rainfall runoff. Trash and Debris Accumulation that exceeds 1 CF per 1000-SF of Trash and debas removed from pond area. pond. InIeV Outlet Pipe InIeU Outlet pipe clogged with sediment and/or No dogging or blockage in the debris material. inlet and outlet piping. Sediment Sediment accumulations in pond bottom that Removal of sediment from pond Accumulation in Pond exceeds the deptfi of sediment zone plus 6-ind�es, bottom. Bottom usually the first cell. Oil Sheen o�Water Prevalent and visible oil sheen. Removal of sediment from pond bottom. Erosion Erosion of the pond's side slopes and/or scouring of Slopes should be stabilized by the pond bottom,that exceeds 6-inches,or where using proper erosion control continued erosion is prevalent. measures,and repair methods. Settlement of Pond My part of these components that has settled 4- Dike!berm is repaired to Dike/Berm incF►es or lower lhan the design elevation,or specifications. inspector detertnines dike/berm is unsound. Rodc Window Rodc windcw is clogged with sediment wndow is free of sediment and debris. Overflow Spillway Rodc is missing and soil is exposed at top of Replace rocks to specifications. spillway or outside slope. 9/1/98 1998 Surface Water Design Manual A-12 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITTES N0. 13-WATER QUALITY FACILITIES(CONT1NUEf� D.)Wetvaults � Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Wetvault Trash/Debris Trash and debris accumulated in vauit,pipe or Trash and debris removed from Accumulation inleU outlet,(includes floatables and non- vault floatables). SedimeM Accumulation Sediment accumulation in vault bottom that Removal of sediment from vault , in Vault exceeds the depth of the sediment zone pius 6- inches. Damaged Pipes InIeU outlet piping damaged or broken and in Pipe repaired and/or replaced. need of repair. Access Cover Cover cannot be opened or removed,especially Pipe repaired or replaced to Damaged/Not Working by one person. proper working speafica6ons. Vault Structure Vault Cradcs wider than 1/2-inch and any No cradcs wider than 1/4inch at Damaged evidence of soil particles entering the structure the joint of the inleU outlet pipe. through the cracks,or maintenance/inspection Vault is determined to be personnel determines that the vault is not structurally sound. structuralry sound. Baffles Baffles corroding,cracldng,warping and/or Repair or replace baffles to showing signs of failure as determined by speafications. maintenance/inspection staff. Access Ladder Damage Ladder is corroded or deteriorated,not functioning Ladder replaced or repaired to properly,missing rungs,has cracks and/or specifications,and is safe to misaligned. use as determined by inspection personnel. 1998 Surface Water Design Manual 9/1/98 A-13 APPENDIX A MAIMENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES N0. 13-WATER QUALITY FACILITiES(CONTINUED� E.) Sand Filters Maintenance Defect Condition When Mai�tenance is Needed Results Expected When Component Maintenance is Performed Abo�e Ground Sediment Sediment depth exceeds 1/2-inch. No sediment deposit on grass Accumulation on Grass layer of sand filter which would Layer impede permeability of the filter section. Trash and Debris Trash and deb�s accumulated on sand filter bed. Trash and debris removed from Accumulations sand filter bed. � SedimenU Debris in When the yard drain CB's and dean-out become Sediment,material from the Yard Drains/Clean- full or partially plugged with sediment and/or CB's and clean-outs removed. Outs] debris. Vegeta6on When the grass becomes excessively tall(greater Vegeta6on is mowed or than 6-inches);when nuisance weeds and other nuisance vegetation is vegetation starts to take over. eradicated,such that flow is not impeded. Sand Filter Media Drawdown of water through the sand filter media, Usualfy requi�es replacement of takes longer than 24-hours,and!or flow through top 6 to 12-inches of inedia. • the overflow pipes occurs frequentiy. May require replacement of entire sand filter section, depending on section. Prolonged flows Sand is saturated for prolonged periods of time Limit the low,continuous flows (several weeks)and does not dry out between to a small portion of the facility stortns due to continuous base flow or prolonged by using a bw wooden divider or flows from detention facilities. slighUy depressed sand surface. Short Circuiting When flows become concentrated over the sand Flow and percolation of water filter rather thar�a�spersed. through the sand fifter is uniform and dispersed across the fifter section. Erosion Damage to Erosion over 2-inches deep where cause of Slopes should be stabilized by Slopes damage is prevalent or potential for continued using proper erosion control erosion is evident measures. Rock Pad Missing or Soil beneath the rock is visible. Replace or rebuild the rock pad Out of Place to design specifications. V-Notch Pipe Weir When the V-Notch pipe becomes damaged or Clean and properly functioning dogged with sedimenU debris. weir,such ihat flows uniformly spread. Damaged Pipes Any part of the piping that is crushed or deforrned Pipe repaired or replaced. more than 20'/0 or any other failure to the piping. � Below C,round Sediment Sediment depth exceeds 1/2-inch. No sediment deposits on sand ' Vault. Accumulation on Sand filter section,which would Media Section impede permeability of the filter section. Sediment Sediment depth exceeds 6-inches in vault bottom. No sediment deposit in the first Accumula6on in Vault chamber of the vault. ' Trash/Debris Trash and debris accumulated in vault,or pipe Trash and debris removed from I Accumulation inleU outlet,floatables and non-floatables vauft,and inleU ouUet piping. Sediment in Drain When drain pipes,cleanouts,and yard drains Remove the material from the Pipes!Yard Drains/ become full with sediment and!or debris. facilities. Cleanouts 9/1/98 1998 Surface Water Design h�Sanual A-14 APPENDIX A MAINTENANCE STAI�DARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES N0. 13-WATER GIUALITY FACILITIES(COMINUED� E.)Sand Fitters (Continued) Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintena�ce is Pertormed Below Ground Short Circuiting When seepage/flow occurs along the vault walls Sand filter media section re-laid Vault(Continued) and comers. and compacted along perimeter of vauft to form a semi-seal. Vertical Riser Pipes Plugged,failure due to cracking deformation.Flows Clean out the riser pipe;�eplace tend to back-up in first chamber of the vault. pipe as needed. Damaged Pipes Inlet or outfet pping damaged or broken and in Pipe repaired and/or replaced. � need of repair. Access Cover Cover cannot be opened,one person cannot open Cover repaired to proper Damaged/Not the cover,corrosioN deformation of cover. working specifications or Working replaced. Vault Structure Cracks wider than 1/2-inch and any evidence of soil Vault replaced or repaired to Damaged;Includes partides entering the structure through the cracks, design specifications. Cracks in Walls, or maintenance/inspection personnel determines Bottom,Damage to that the vauR is not structurally sound. Frame and/or Top Slab. Cracks wider than 1!2-inch at the joints of any inleU No cracks more than t/4-inch outlet ppe or any evidence of soil particles entering wide at the joint of the inleV the vauft through the walls. outlet pipe. Baffles Baffles corroding,cracldng,warping and/or showing Repair or replace baffles to signs of failure as determined by maintenance/ specifications. inspection person. Access Ladder Ladder is corroded or deteriorated,not functioning Ladder replaced or repaired to Damaged prope�ty,missing rungs,cradcs,and misaligned. specifications,and is safe to use as detertnined by inspection personnel. 1998 Surface W'ater Desi�n Alanual 9/1/98 A-15 APPE'�1DIX A M.AI\'TEN.�'�10E STANDARDS FOR PRIVATELY'�1AI'v'TAINED DRAI�AGE FACILITIES N0. 13-WATER QUALITY FACtLITtES(CONTINUED� F.) Leaf Compost Filters Maintenance Defect Conditions When Maintenance is Needed Results Expected When , Component Maintenance is Pertormed Above Ground Sediment Sediment depth exceeds 025-inches. No sediment deposits on fabric Open Swale accumulation on Geo- layer which would impede Textile/media permeability of the fabric. Trash and debris Trash and debris accumulated on compost fitter Trash and debris removed from accumulations bed. compost filter bed. SedimenU debris in When the yard drain CB's and dean-0uts become Remove the accumulated draiN yard drains/ full of sediment and/or debris. material from the facility. cl ean-outs. Vegetation Vegetation impending flow through section,or Vegetation is mowed or encroaching into compost media. eradicated such that flow is no I longer impeded. � , Leaf Compost Media Drawdown of wate�through the leaf compost, Replace media with new to � takes longer than 12-hours,and/or flow through design specifications,i�addition I the overflow pipes occurs frequently. to replacing fabric. ' Short-Circuiting When Channeled flow occurs over the leaf inedia; Flow is uniform over the entire and where flow perks through the media at the width of the media section,and baffles. concentrated percolation dces not occur at the baffle walls. Media needs to be graded and re-set at the baffles to form a seal.Weir plate may need to be adjusted in addition. Erosion Damage to Eroded damage over 2-inches deep where cause Slopes should be stabilized by Slopes of damage is prevalent or potenfial for continued using proper erosion control erosion is prevalent measu�es. Damaged Geo-Textile When fabric is tom,deteriorated,raveled,etc. Fabric replaced as necessary. Fabric. Rock Pad Missing or Sal beneath the pad is visible. Replace or rebuild the rock pad out of place to design standards. Damaged Pipes Any part of the pipe system that is crushed, Pipe repaired or replaced. damage due to corrosion,and/or settlement. V-Notch Weir Flow is not being uniformly spread over filter C1ean,repair or replace the weir Assemblies media. systems. Below Ground Sediment Sediment depth exceeds 025-inches. No sediment deposits on fabric Vault Accumulation on Geo- layer which would impede Textile/Media. permeability of the fabric and compost media Sediment Sediment depth exceeds 6-inches in first chamber. No sediment deposits in vault Accumulation in Vault bottom of first chamber. Trash!Debris Trash and debris accumulated on compost filter Trash and debris removed from Accumulation bed. the compost filter bed. Sediment in Drain When drain pipes,Gean-outs,yard drains become Remove the accumulated Pipes/Yard Drains/ full with sediment and/or debris. material from the facilities. Clean-Outs 9/1/98 1998 Surface Water Design Manual A-16 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILTITES N0. 13-WATER QUALITY FACILITIES(CONTINUED� F.) Leaf Compost Filter(Continued) ' Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Below Ground Leaf Compost M�a Drawdown of water tfirough the leaf compost,takes Replace media with new longer than 12-hours,and/or overflow occurs compost to specifications,in frequenUy. addition to replacing fabric. Short Circuiting When seepage occurs along the vauft wall and Percolation of water occurs comers occur. along the walls and comers and not through the media section. . Media needs to be re-set along the vault wall and comers to form a semi-seal. Plugged/Damaged Flow tends to backup unusually high in the first Clean out the elbow fittings and/ Elbows chamber of the vault. or replace'rf damaged. Damaged Geo-Textile Fabric is tom,deteriorated,raveled,etc. Fabric replaced as necessary. Fabric Rock Pad Missing or Soil beneath the pad is visible. Replace or rebuild the rock pad Out of Place to design sTandards. Damaged Pipes My part of the pipes that are crushed,damaged Pipe repaired and/or replaced. due to corrosion and/or settlement. Access Cover Cover cannot be opened,one person cannot open Cover repaired to proper Damaged/Not the cover,corrosion/deformation of cover. working specificatio�s or Working replaced. V-Notch Weir Flow does not spread un'rformly over fifter media by Clean,repair and/or replace the Assemblies weir section. weir plate section,or adjust height Vautt Structure Cracks wider than 1/2-inch and any evidence of sal Vautt replaced or repaired to Indudes Cracks in particles entering fhe structure through 1he cracks, design specifica6ons. Wall,Bottom, or maintenance/inspection personnel determines Damage to Frame that the vault is not structuralty sound. and/or Top Slab Baffles Baffles corroding,cracking warping,and/or showi�g Repair or replace baffles to signs of failure as determined by maintenance/ specification. inspection person. Access Ladder Ladder is corroded or deteriorated,not functioning Ladder replaced or repaired and Damaged property,missing rungs,cracks,and misaligned. meets specifications,and is safe to use as determined by inspection persoruiel. Cracks wider than 1/2-inch at the jant of any No cxacks more than 1/4-inch inleVoutlet pipe or any evidence of soil partiGes wide at the joint of the inleU entering the vault ihrough the walls. outlet pipe. � , i i 1998 Surface Water Design Manual 9/1/98 A-17 APPENDIX A MAINT'ENANCE STAI�TDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES N0. 13-WATER QUALITY FACILITIES(CONTINUED� _G.) Infiltration Ponds Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Mainte�ance is Pertormed . Infiltration Pond Vegetalion Vegetation such as grass and weeds needs to be Vegetation should be mowed to mowed when it starts to impede infiltration function. 2-inches i�height.Trees and Mowing is generally required when height exceeds bushes should be removed 12 inches. where they impact the infiltrating area of the pond. Sand FiRer Layer Sand filter layer has sediment deposits that exceeds Remove sediment and top layer 1/2-inch or the infiltration rate of the sand layer is of sand,and replace in kind per less than 2 in/hr. specification. Sediment Sediment accumulations in pond bottom that Removal of sediment from pond Accumulation in exceeds 1/2-inch in depth or percolation test of the bottom. Pond Bottom pond indicates facility is only working at 90%of iYs design pe�colation rate. Trash and Debris Accumulation that exceeds 1-CF per 1,000-SF of Trash and Debris removed from pond area. pond. InIeU Outlet Pipe InIeU outlet pipe clogged with sediment and/or No dogging or blockage in the debris material. inlet and outlet piping. Erosion Erosion of the pond's side slope and/or scouring of Slopes should be stabilized by the pond bottom,that exceeds 2-inches,or where using proper erosion control potential for continued erosion is prevalent measures and repair methods. Sediment of Pond Any part of these compo�ents that has settled 4- Slopes should be stabifized by Dike/Berm inches or lower than the design elevation,or where using proper erosion contrG potential for continued erosion is prevalent. measures and repair methods. � ', Rodc Window Rock window is dogged with sediment Window is free of sediment and debris. Overflow Spillway Rock is missing and soil is exposed Replace rocks to specifications. InBttration VaulU Sediment Tanks:Sediment depth exceeds 6-inches in depth. No sediment deposits in tank Tank Accumulation in bottom. Vault Trash and Debris Trash and debris accumulated in tank,vault or Trash and debris removed from Accumulation connecting pipe.Indudes floatables and non- each facility. floatables. Access Cover Cover cannot be opened or removed,especially by Cover repaired or replaced to Damaged/Not one person. proper working specificafions or Working replaced. Tank or Vault Tank:Jants between tank sections failing,such thaY Tank replaced or repaired to Structure Damaged leakage occurs and.or material being washed design specificafions. • through into facility;or maintenance/inspection person determines the tank is not structurally sound. 'j ', --i , 9/1/98 1498 Surface Water Design Manual � A-18 APPENDIX A MAIM'ENANCE STANDARDS FOR PRNATELY MAINTAINED DRAINAGE FACILI'TIES N0. 13-WATER QUALITY FACILlT1ES(CONTINUED� G.) Infiltration Ponds (Continuea� Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Pertormed Infiltration VauR/ Tank or VauR Structural Vault:Cracks wider than 1f2-inch and any Tank replaced or repaired to Tank Damage evidence of soil partides entering ri�e structure design specifica6ons. through the cracks,or maintenance inspection personnel determines that the vault is not structurally sound. Access Ladder Damaged Ladder is corroded or deteriorated,not Ladder replaced or repaired to functioning properiy,missing rungs,has cracks specifications,and is safe to and/or misaligned. use as determined by inspection personnel. : , i . 1998 Surface Water Design Manual 9/1/98 A-19 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILIT�S N0. 14-OIL CONTROL FACILITIES A.j OiV Water Separators Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Pertormed. API Type OWS Monitoring inspection of discharge water for obvious signs Effluent discharge from vault of poor water qualiry. should be dear with out thick visible sheen. Sediment Accumulation Sediment depth in bottom of vauft exceeds 6- No sediment deposits on vauft inches in depth. bottom which would impede flow through the vault and separation efficiency. Trash and Deb�s Trash and debris accumulation in vault,or pipe Trash and debris removed from Accumulation inleU outlet,floatables and non-floatables. vault,and inleU oudet piping. Oil Accumulation Oil accumulations that exceed 1-inch,at the Extract oi1 from vault by surface of the water vactoring.Disposal in accordance with state and local rules and regulations. Damaged Pipes Inlet or ouUet piping damaged or broken and in Pipe repai�ed or replaced. need of repair. - Access Cover Damaged/ Cover cannot be opened,one person cannot Cover repaired to proper Not Worldng ope�the cover,corrosioN defortnation of cover. worlcing spedfications or replaced. Vauft Structure Damage- Cracks wider than 1/2-inch and any evidence of Vault replaced or repaired to Indudes Cracks in Walls soil partides entering the structure through the design specifica6ons. Bottom,Damage to cradcs,or maintenanceJ inspeciion personnel Frame and/or Top Slab determines that the vault is not structuralty sound. Baffles Baffles corroding,cracking,warpir,�and!or Repair or replace baffles to showing signs of failure as detertnined by specifications. maintenance/inspection person. Access Ladder Damaged Ladde�is corcoded or deteriorated,not Ladder replaced or repaired and functioning properly,missing rungs,cracks,and meets specifications,and is misaligned. safe to use as determined by inspection personnel. Cracks wider than 1!2-inch at the jant of any No cxacks more than 1/4-inch inleU oudet pipe or any evidence of soil particles wide at the joint of the inleU entering the vault through the walls. oudet pipe. CPS-Type OWS Monitoring Inspec6on of discharge water for obvious signs Effluent discharge from vautt of poor water quality. should be dear with no thick visible sheen. Sediment Accumulation Sediment deptfi in bottom of vault exceeds 6- No sediment deposits o�vauR inches in depth and/or visible signs of sediment bottom and plate media,which on plates. would impede flow through the vault and separation e(ficiency. Trash and Debris Trash and debris accumulated in vault,or pipe Trash and debris removed from Accumulation inleU outlet,floatables and non-floatables. vault,and inleU ouUet piping. Oil Accumulation Oil accumulation that exceeds 1-inch at the Extract oil from vault by I water surface. vactoring methods.Clean I coalescing plates by thoroughly rinsing and flushing.Should be no visible oil deptfi on water. 9/1/98 1998 Surface�Vater Design Manual A-20 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITTES I NO. i 4-OIL CONTROL FAClLIT1ES(CONTINUED� A.) OiV Water Separators (Continued) ' Aaintenance Defect Condition When Maintenance is Needed Results Expected When .:omponent Maintenance is Pertormed Damaged Coalescing Plate media broken,deformed,cracked and/or Replace that portion of inedia Plates showing signs of failure. padc or entire plate pack dependng on severity of failure. Damaged Pipes Inlet or outlet piping damaged or broken and in need Pipe repaired and or replaced. of repair. Baffles Baffles coRoding,cracking,warping and/or showing Repair or replace baffles to signs of failure as determined by maintenance/ specifications. inspection person. Vault Structure Cracks wider than 1/2-inch and any evidence of soil Vault replaced or repaired to Damage-Includes partiGes entering the sUucture through the cradcs, design specifications. Cracks in Walls, or maintenance inspection personnel determines Bottom,Damage to that the vault is not structurally sound. Frame and/or Top Slab Access Ladder Ladder is corroded or deteriorated,not functioning Ladder replaced or repaired and Damaged properly,missing rungs,cracks,and misaligned. meets specifications,and is safe to use as detertnined by inspection personnel. Cracks wider than 1/2-inch at the joint of any inleU No cracks more than 114inch outlet pipe or any evidence of soil particles entenng wide at the joint of the inleU the vault through the walls. outlet pipe. 9.)Catch Basin Inserts Aaintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Catch Basin Sediment When sediment forms a cap over the insert media of No sediment cap on the inseR Accumulation the insert and/or unit. media and iYs unit Trash and Debris Trash and debris accumulates on insert unit creating Trash and debris removed from Accumulation a bbdcage/restriction. insert unit.Runoff freely flows into catch basin. Inspection InspecUon of inedia insert is required. Effluent water from media insert is free of oils and has no visible sheen. Media lnseR-Water Catch basin insert is saturated witl�water,which no Remove and replace media Saturated bnger has the capacity to absorb. insert � Media lnsert-Oil Media oil saturated due to peVoleum spill that drains Remove and replace media Saturated into catch basin. insert. General Regular interval replacement due to typical average Remove and replace media at life of inedia insert product. regular intervals,depending on insert product. 1998 Surface Water Design Manual 9/1/98 A-21