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............. ............. .............. ............................. .......... .............................. .......... ........................... ........................................... .............. ..................... ....I..................-.......... STORM DRAINAGE REPORT FOR TALL FAIRS TOWN HOMES RENTON, WASHINGTON .... .. OUR JOB NO. 5025 PREPARED BY: BARGHAUSEN CONSULTING ENGINEERS, INC. 18215 72nd Avenue South Kent, Washington 98032 (206) 251-6222 February 28, 1994 TABLE OF CONTENTS I. INTRODUCTION/GENERAL INFORMATION A. General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. TIR Work Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . II. PRELIMINARY CONDITION SUMMARY III. OFF-SITE ANALYSIS A. Upstream Drainage Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Downstream Drainage Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV. RETENTION/DETENTION ANALYSIS AND DESIGN A. Existing Site Hydrology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Developed Site Hydrology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Hydrologic Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • D. Retention/Detention System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. CONVEYANCE SYSTEM DESIGN ANALYSIS VI. SPECIAL REPORT STUDY VII. BASIN AND COMMITTEE PLAN AREAS VIII. OTHER PERMITS IX. TEMPORARY EROSION/SEDIMENTATION CONTROL DESIGN X. ADDITIONAL DOCUMENTS Xl. MAINTENANCE AND OPERATION MANUAL • 5025.001 [AS/sdc] I. PROJECT OVERVIEW I. INTRODUCTION/GENERAL INFORMATION • The project lies within the portion of the southwest quarter of Section 3, Township 23 North, Range 5 East, Willamette Meridian, King County, Washington, and is approximately 3.2 acres in size. The existing site consists of 3 houses located at the south portion of the property along Sunset Boulevard. The remainder of the area is undeveloped and is covered with evergreen and Douglas Fir trees and undergrowth consisting of many forms of grass and shrubs. The property is basically trapezoidal in shape and contains approximately 314 feet of frontage to the south along Sunset Boulevard. The property is bounded to the north by undeveloped properties and existing residential houses, to the east by an existing Summer Wind subdivision, and to the west by Shannon Village Commercial and Business Center. The overall topography of the site generally slopes from north to south with an approximate slope of 6 to 8 percent. The on-site soil has been classified as Alderwood gravelly sandy loam in accordance with the King County Soil Survey Map. The proposed project is for construction of a 37-unit town house project. Page 1 of 11 5025.001 [As/sdcl Page 1 of 2 • King County Building and Land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET PROJECTPART I OWNER AND PART 2 PROJECT • • PROJECT • ProjectOwner SEATTLE—RENTON INVESTORS Project Name TALL FIRS TOWNHOMES Address 14200 S.E. 272ND #E_T03 KENT WA Location l 23N 98042 630-6845 Township Phone 5E Project Engineer ALI SADR, P.E. Range 3 BARGHAUSEN CONSULTING ENGINEERS Section Company Project Size 3.2 AC Address Phone 18215 72ND AVE SO KENT WA 98032 251— Upstream Drainage Basin Size 0 AC PART 3 TYPE OF PERMIT APPLICATION PART 4 OTHER PERMITS 0 Subdivision ED DOF/G HPA 0 Shoreline Management 0 Short Subdivision 0 COE 404 0 Rockery 0 Grading 0 DOE Dam Safety ® Structural Vaults [jl Commercial 0 FEMA Floodplain 0 Other 0 Other 0 COE Wetlands 0 HPA COMMUNITYPARTS SITE DRAINAGE • i Community NEW CASTLE Drainage Basin CEDAR RIVER BASIN PART 6 SITE CHARACTERISTICS 0 River 0 Floodplain 0 Stream 0 Wetlands 0 Critical Stream Reach 0 Seeps/Springs Depressions/Swales 0 High Groundwater Table i 0 Lake 0 Groundwater Recharge 0 Steep Slopes 0 Gther Lakeside/Erosion Hazard i SOILSPART 7 i Soil Type Slopes Erosion Potential Erosive Velocities A.g.c 5% MODERATE t-J Additional Sheets Attatched - Page 2 of 2 King County Building and Land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET PART 8 DEVELOPMENT LIMITATIONS REFERENCE LIMITATION/SITE CONSTRAINT F-1 Ch.4-Downstream Analysis 1-1 0 0 0 Additional Sheets Attatched PART 9 ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION FOLLOWING CONSTRUCTION ® Sedimentation Facilities Stabilize Exposed Surface . FX--] Stabilized Construction Entrance F-1 Remove and Restore Temporary ESC Facilities ® Perimeter Runoff Control ® Clean and Remove All Silt and Debris ® Clearing and Grading Restrictions Ensure Operation of Permanent Facilities Cn Cover Practices Flag Limits of NGPES ® Construction Sequence Other Other ;Iially M. ® Grass Lined Channel F-� Tank Infiltration Method of Analysis Pipe System ® Vault Depression S.B.U.H. Open Channel = Energy Dissapator 0 Flow Dispersal Compensation/Mitigation Dry Pond = Wetland 0 Waiver of Eliminated Site Storage 0 Wet Pond = Stream Regional Detention Brief Description of System Operation TIGHT LINE STORM DRAINAGE SYSTEM TO DETENTION VAULT DISCHARGES THROUGH MULTIPLE ORFICE CONTROL STRUCTURES TO GRASS LINED SWALE AND DISCH GES Ukil Facility Related Site Limitations E::] Additional Sheets Attatched. Reference Facility Limitation specialPART 11 STRUCTURAL ANALYSIS (May require � Drainage Easement [X-J Cast in Place Vault F-1 Other E::] Access Easement 0 Retaining Wall E:j Native Growth Protection Easement E::] Rockery>4'High 0 Tract 0 Structural on Steep Slope 0 Other OF - • • I or a civil engineer under my supervision have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attatchments. To the best of my knowledge the information provided SlyrwdD.t. here is accurate. • II. PRELIMINARY CONDITION SUMMARY • Page 2 of 11 5025.001 [AS/sdc] p JAN EDWARD A.McHUGH JR.,ARCHITECT" May 4, 1992 OFFICE OF THE HEARING EXAMINER CITY OF RENTON REPORT AND RECOMMENDATION APPLICANT: SEATTLE-RENTON INVESTORS Tall Firs Townhomes File No.: CU;R-056-91 LOCATION: 4808 NE Sunset Boulevard SUMMARY OF REQUEST: Rezone from G-1, General Zone to R-2, Residential with a Conditional Use Permit to allow 37 townhouses with three (3) or more dwelling units in a building. SUMMARY OF ACTION: Planning Division Recommendation: Approval with Conditions PLANNING DIVISION REPORT: The Planning Division Report was received by the Examiner on April 7, 1992 PUBLIC HEARING: After reviewing the Planning Division Report, examining available information on file with the application, and field checking the property and surrounding area, the Examiner conducted a public hearing on the subject as follows: MINUTES The hearing was opened on April 14, 1992 at 10:50 a.m. in the Council Chambers of the Renton Municipal Building. Parties wishing to testify were affirmed by the Examiner. The following exhibits were entered into the record: r Exhibit #1 - Yellow File containing application, proof of posting and publication and other documentation pertinent to this request. , Exhibit #2 - Neighborhood Vicinity Map Exhibit #3 - Proposed Site Plan Exhibit #4 - Site Plan in Relation to Book/Bales Project The Examiner said these minutes will incorporate by reference the minutes from the prior hearing, Book/Bales, #R;SA;PP-110-91, in regards to the aquifer, the sanitary sewer, and a shared emergency access exit. l lU;t�-UFO-71 May 4, 1992 Page 2 The hearing opened with a presentation of the staff report by PAUL FORSANDER, Senior Planner, who said the purpose of changing the zoning from G-1 General Single Family to R-2, which permits duplex units and the Conditional Use Permit, was to allow increased density to permit 37 townhouses on the site, three or more dwelling units in each building. The project was located east of Duvall, west of the existing Summerwind single-family development, and access would be from Sunset Boulevard. The Comprehensive.Plan designation was low density, multi-family. The proposal would develop 37 two and three bedroom townhouse apartments in an eight-building complex on a 3.13 acre site located approximately 200 feet east of Duvall Avenue NE. Total building area would be approximately 48,000 sf, with a 27,000 sf foot print. Building #1 would have six units, building #2 would have four units, building #3 would have four units, building #4 would have five units, building #5 would have four units, building #6 would have four units, building #7 would have four units and building #8 would have six units. The resulting proposed density would be almost 12 units per acre, with proposed site coverage at 20%. 56 parking spaces would be required and the applicant was proposing 70 spaces, a ratio of 1.9 spaces per dwelling unit, 53 of those enclosed in garages. The Examiner asked how many units would normally fit on this site if it was developed in a fashion similar to the Book/Bales site. Mr. Forsander answered perhaps 20 units, and said the density was consistent with the Comprehensive Plan; the Environmental Review Committee issued a determination of Non-Significance-Mitigated on February 5, 1992, and no appeals were filed. Regarding ERC condition #2, prior to the hearing the applicant was to modify interior noise levels in buildings # e no more than 55 DB's. Modifications were to include additional landscaoing and/or additional sound proofing. and applicant was to retain a qualified noise consultant. This requirement should be modified to allow the applicant to do the noise study prior to issuance of a building permit. The applicant had indicated that they would implement the improvements recommended by the noise consultant. ERC condition #3 addressed potential light and glare impacts from the parking lot onto the Summerwind development. After a staff visit to the site found an existing 6-foot fence along the property line on the west side of the single-family development, staffs recommendation was to delete ERC's condition #3. Some departmental comments in the staff report noting "do not approve" referred to waiting until after the . construction permits were gained. Mr. Forsander noted that the proposal met rezone criteria. Staff felt that the project provided a buffer zone between the commercial uses to the west and south and the single-family uses to the north and J east. Regarding timeliness, the sewer capacity question seemed to be the main issue. Mr. Forsander said that this was an issue that perhaps the City Council needed to deal with and he recommend that the Examiner approve, with the condition that the applicant work with staff to provide information for c a Council decision. There were less than 12 units per acre, there was consistency with the zoning code, the proposal was consistent with development standards for setbacks, building heights, lot coverage, and Q parking. There was no detrimental over-concentration of construction of this type in the area. The Examiner said the western side yard of building #8 seemed relatively close to the rear of a retail U facade. He was also concerned about the 30-foot set back from Sunset, a major arterial, and sound levels. Mr. Forsander said he'd have to look at the file, but there might not be windows on that side. He also said staff had worked with the applicant to provide better circulation, more central open space, +• b tter separation. and stepping of the buildings The building heights varied between 28 - 35 feet, and these units had been esigne to similar in character to the adjacent Summerwind development, using appropriate materials. A strong effort had been made to preserve the fir trees on the site. The applicant provided a traffic impact analysis which showed the site would have minimal impact on traffic. Vehicular and pedestrian traffic were separated by pedestrian walkways. Emergency fire access to the Book/Bales project was to be through the Tall Firs development. The ERC was concerned about the affects of traffic noise on the residents, and condition #2 required study and modification of building design. Staff recommended that the Examiner modify the ERC condition to allow the applicant be able to make the noise modifications following the hearing but prior to City Council approval. The proposal had extensive landscaping, open spaces, and a play area, all connected by the Seattle-Renton Investors CU;R-056-91 May 4, 1992 Page 3 Owalkway system. Based on utility staff comments, Mr. Forsander said his reading was that there was adequate sewer and stormwater utilities, but staff reser a right to re uire a downstream analysis Mr. Forsander recommended approval of the con itional use request and asked t e Examiner to recommend approval of the Rezone to the City Council, with suggested conditions set out by staff (copy of staff conditions attached.) Regarding staff condition #5 b, tree replacement, Mr. Forsander stated that staff would be willing to work with the applicant and the Examiner to come up with language that was appropriate, reasonable, and better suited the intent to maintain landscaping. Responding first for the applicant was LEONARD MILBRANDT, 11715 SE 5th, Suite 100, Bellevue, WA 98005, who stated that 15 - 18 neighbors were able to review the site plans at a meeting and it was favorably received. Negotiation with staff had resulted in the creation of larger open space, pathways independent from driveways, and an enhanced visual impact on the eastern boundary achieved by increasing the landscaping setback and density. Bollards would be provided and the applicant would work with staff to assure that the fire lane to the Book/Bales project would note bloc ct—ed-at either end.end. Out of over 200 significant trees on the site, 70 (43%) would be removed for construction, but significant tree stands were being preserved. He questioned if the tree replacement applied to trees removed during construction. The Examiner said he thought that only applied to after the initial construction period, and staff would be looking at the language of the tree replacement requirement. Mr. Milbrandt noted that buildings had been reoriented to better shield from street sound impacts. The berm alon the property line the fence and the biofiltration swale also would serve to protect the building from street noise. A level 1 drainage report had been provide a ong—with a traffic study and a soils report. The applicant had agreed to sound mitigation, fire mitigation, parks mitigation, off- site improvements, and the sewer study. The sewer was a potential problem at peak times that would be solved by 1993 with the new May Creek and Honey Creek lines. He didn't believe that this potential •problem could be grounds to deny the project as occupancy permits for these buildings would not be obtained before 1993. He believed the applicant had done everything necessary to facilitate the processing of this project which would provide much needed affordable housii filing the gap between new houses and rentals. Density would be 11.8 units per acre. e urged approval of the project. RON TREMAINE, Prell Development, Project Manager for Tall Firs, 14200 SE 272nd, Suite E-203, Kent, WA 98042, said he had spoken three times with the sewer department and was told there would be no problem with sewer availability. He also spoke with them regarding the downstream analysis requirement, and was told there would be no problem. The problem seemed to be with water leaking into the system, which would be remedied by the time of construction. Several times the Examiner had mentioned his concern about subsequent buyers being unaware of sewer problems. The Examiner said you have met with them three times and been told there was no problem, and yet today we were told there was a problem. He didn't want that to happen to another purchaser. Mr. Milbrandt said that a representative of the sewer department had told him today that if, for some reason this couldn't be built out, although they felt it could be, they would go to the Council and ask for a moratorium. The Examiner called for further testimony regarding this project. There was no one else wishing to speak, and no further comments from staff. The Examiner asked for one additional week to consider his decision and there was no objection. The hearing closed at 11:30 a.m. A.M. FINDINGS, CONCLUSIONS & DECISION: Having reviewed the record in this matter, the Examiner now makes and enters th�.follovying • J CU;R-056-91 May 4, 1992 Page 4 FINDINGS: , 1. The applicant, Seattle-Renton Investors, filed a request for approval of a rezone of approximately 3.13 acres of property from General (Single Family; Lot size - 35,000 sq. ft.) to R-2 (Duplex Residential), together with a request for a conditional use permit to permit up to 12 units per acre. 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, issued a Declaration of Non-Significance (DNS) for the subject proposal. 4. The subject proposal was reviewed by all departments with an interest in the matter. 5. The subject site is located at 4808 NE Sunset Boulevard. The subject site is located on the north side of Sunset between Duvall Avenue NE and Field Avenue NE. 6. Any development still located on the site would be removed and replaced by 37 townhouse units located in 8 buildings. 7. •The subject site was annexed"to the City with the adoption of Ordinance 2945, enacted in July, 1975. The current General (Single Family; Lot size - 35,000 sq. ft.) zone was adopted automatically on annexation. 8. The map element of the Comprehensive Plan designates the area in which the subject site is . located as suitable for the development of low density multiple-family uses and office park type uses, but does not mandate such development without consideration of other policies of the Plan. 9. The approximately 3.13 acre parcel is an irregularly-shaped parcel with the south boundary dictated by the angular alignment of Sunset in this location. The west property line is 458.80 feet long. The north property line is 331.19 feet long. The east property line is 359.41 feet long. The south boundary is defined by a short 30.60 foot-long segment and a long 314.26 foot segment. 10. The site slopes upward from the south to the north. 11. The zoning in the area is mixed with Single family, R-1, zoning located north and east of the site, and Commercial, B-1, zoning located west of the site. West of Duvall is R-1 zoning, and G-1 zoning, the category of the subject site. North of the subject site are additional G-1 zoned parcels. One of these G-1 parcels is proposed for R-2 and O-P zoning in a companion proposal. The two proposals would provide each other with a second, emergency access. 12. The applicant proposes constructing 8 buildings on the site. The buildings are numbered 1 through 8 and more or less run counterclockwise around the site starting at the southwest corner of the site. There will be a total of 37 dwelling units divided as follows: Buildings #1 and #8: 6 units; Buildings #2, #3, #5, #6, and #7: 4 units; and Building #4: 5 units. $vluoItic, S Seattle-Renton Investors CU;R-056-91 May 4, 1992 Page 5 1013. The applicant will provide most of the parking in garages in each of the buildings with 53 garage stalls. There will also be 17 outside stalls inc� 3 handicapped stalls for a total parking complement of 70 stalls whereas only 56 stalls are required. Since on-street parking is not available in this location, the excess parking appears appropriate. 14. The buildings will be two and three story, approximately 25 to 35 feet tall, buildings. The buildings take advantage of the sloping topography and are stepped into the hillside. In addition to following the contours of the site, the building will ave peaked roofs and articulated facades. The buildings are also placed on the site in differing angles and will not present a rigid row-type appearance. 16. In addition to saving a substantial number of the significant trees found on the site, the applicant will be adding landscaping around the buildings and in the open spaces. Large expanses of trees will be preserved along the north property line and along the middle of the west property line. 17. The buildings are also set back from the property lines up to 30 or more feet providing good buffering for neighboring properties. Only Building #8 is closer than the average setback and in that case it presents a sidewall to the property line. 18. The applicant proposes a play area along the western side of the complex, screened trash dumpsters, and paths linking the buildings with each other and the street. 19. The applicant will provide secondary emergency access to the site from the northwest corner, linking it with a proposed office building parking lot in that location. 20. The site is served by the Renton School district. Assignments are determined by available space. 21. The City provides water and sewer infra-structure. There is a potential sewer capacity problem and staff has recommended that an analysis be done. The issue is whether a site should be reclassified to permit more intense uses when the sewer capacity is unknown. 22. The site is located in Zone 2 of the City's Aquifer Protection Area. CONCLUSIONS Rezone 1. The proponent of a rezone must demonstrate that the request is in the public interest, that it will not impair the public health, safety and welfare and in addition, complies with at least one of the criteria found in Section 4-8-14, which provides in part that: a. The subject site has not been considered in a previous area-wide rezone or land use analysis; or b. The subject site is potentially designated for the new classification per the Comprehensive Plan; or C. There has been a material and substantial change in the area in which the subject site is located since the last rezoning of the property or area. l k-)1--,. V-- May 4, 1992 Page 6 The requested classification is appropriate and should be approved. • 2. The proposed R-2 zoning is compatible with both the Comprehensive Plan and the proposed rezoning of the adjacent site to the north. While the map element of the Comprehensive Plan is not precise, the site, at the northeast corner of the Sunset/Duvall intersection, falls on the boundary between single-family uses, commercial uses and low density multiple-family uses. 3. In addition to this map designation of the site as suitable for duplex development, the goals and policies'of the Comprehensive Plan call for reasonable transitions between zones and permitting transitional-type land uses to serve as buffers between more intensive and less intensive uses. The site will provide a reasonable transition from the commercial uses immediately west of the site to the single-family uses east of the site. 4. The duplex zoning will provide additional housing choices for those who are not interested in single-family housing in an area where urban services, shopping and some employment opportunities exist. 5. The site has not been recently considered for rezoning and the Comprehensive Plan's designation seems appropriate for this site. 6. There has been considerable development in the area in the last five years including single- family uses, multiple-family uses and new commercial uses. In addition, the Duvall intersection was rebuilt within the last few years to accommodate safer traffic movement through the intersection. 7. The sewer issue is one of primary importance, as it was for the adjacent parcel to the north. Can the site be appropriately provided adequate sewer service? While staff has indicated that capacity can probably be found, this issue needs to be highlighted for City Council consideration prior to approving anything that increases the demand on the existing system. Therefore, in addition to requiring covenants that indicate sewer capacity may be a problem, the City Council will be asked to specifically review the sewer issue for this site prior to adopting an ordinance approving the reclassification of the subject site. 8. While at the east margin of the city, the project is still an infill project that makes the most of existing urban services and helps prevent unnecessary sprawl into the more rural areas. Conditional Use Permit 9. The applicant for a Conditional Use Permit must demonstrate that the use is in the public interest, will not impair the health, safety, or welfare of the general public, and is in compliance with the criteria found in Section 4-31-36 (C) which provides in part that. a. The proposal generally conforms with the Comprehensive Plan; b. There is a general community need for the proposed use at the proposed location; C. There will be no undue impacts on adjacent property; d. The proposed use is compatible in scale with the adjacent residential uses, if any; Seattle-Renton Investors CU;R-056-91 May 4, 1992 Page 7 e. Parking, unless otherwise permitted, will not occur in the required yards; f. Traffic and pedestrian circulation will be safe and adequate for the proposed project; g. Noise, light, and glare will not cause an adverse affect on neighboring property; h. Landscaping shall be sufficient to buffer the use from rights-of-way and neighboring property where appropriate; and i. Adequate public services are available to serve the proposal. The requested conditional use appears to satisfy these and other particulars of the ordinance. 10. The proposed site plan for the 37 unit residential complex appears to serve the public use and interest. The buildings are well-separated, provide interesting facades, step into the sloping site, and provide pitched roofs that mirror single-family structures found in the vicinity of the site. 11. The 37 unit complex is compatible with the Comprehensive Plan designation for the site. The plan calls for low density residential development of up to 12 units per acre. The proposed density at 11.82 units per acre falls just shy of the maximum. The setbacks, tree preservation, and additional landscaping proposed will also fulfill the Comprehensive Plan's goals of providing well-designed uses that can serve as buffers between more intense and less intense uses. The site falls between the commercial uses located at the Duvall/Sunset intersection west of the site • and the single-family Summerwind development east of the site. 12. It is always difficult to determine community need for additional dwelling units but it appears that providing additional variety in housing types, low density apartment type units in this case, is appropriate. The uses are close to shopping areas, schools are nearby, and urban services are generally available. 13. The setbacks, design features, and landscaping should allow this use to be a good neighbor to both the commercial uses west of the site and the adjoining residential uses both north and east of the site. 14. The 25-to-35-foot tall buildings are compatible with the scale of surrounding single-family ' development and the low-rise commercial uses located in the vicinity of the subject site. 15. The applicant has provided most of the parking within the proposed buildings, thereby preserving more of the -native vegetation and providing more area for landscaping. The pedestrian paths, vehicle circulation, and emergency access appear reasonable for a development of this size. 16. The development of this parcel will obviously increase, to some extent, noise, light, and glare over the existing amounts but it should not be appreciable. 17. The landscaping, both the tree preservation effort and the supplemental planting, appear adequate to provide an aesthetic environment and adequate buffer to prevent neighborhood deterioration and blight. �eaitie-tten�on �Liv�siorS CU;R-056-91 May 4, 1992 Page 8 18. As with the request to rezone the site, the only substantial issue is the adequacy of the sewer • system. Therefore, the applicant will have to execute restrictive covenants that will inform any potential purchaser that building permits will only be issued by the City if adequate sewer capacity is demonstrated to serve any proposed development. 19. In conclusion, the proposed use appears to present a well designed, functional complex that will provide additional housing opportunities for residents of the City. RECOMMENDATION The City Council should approve the proposed reclassification of the subject site from G-1 to R-2 subject to the following conditions: 1. The City Council should review the capacity of the sewers in the area in light of the current information and determine whether it is appropriate to vest in the applicant additional density given the shifting nature of the capacity of those sewer lines. 2. The applicant shall comply with the conditions imposed by the ERC, as appropriately modified. 3. The applicant shall construct the complex approved under the Conditional Use Permit. DECISION The Conditional Use Permit is approved subject to the following condition: 1. The applicant shall execute restrictive convenants which indicate that building permits • shall not be issued until the City is satisfied that there is adequate sewer capacity to serve any new development. 2. The applicant shall provide $150 for each new dwelling unit as mitigation for the impacts on the City's park system. 3. The applicant shall comply with the sewer and water Comprehensive Plans for the orderly extension of utility lines. -- 4. All landscaping and fencing shall be subject to review and approval of the Planning- Staff to assure that noise, light, and glare does not spill over from the site. . 5. The applicant shall provide measures that ensure that the emergency access road is limited to emergency passage of vehicles. 6. The applicant and staff shall reach acceptable agreement on ensuring the replacement of plant materials required under this original approval. ORDERED THIS 4th day of May, 1992. VCLLl FRED J. KA MAN HEARING E AMINER Seattle-Renton Investors CU;R-056-91 May 4, 1992 Page 9 TRANSMITTED THIS 4th day of May, 1992 to the parties of record: Paul Forsander Senior Planner Leonard Milbrandt 11715 SE 5th, Suite 100 Bellevue, WA 98005 Ron Tremaine Prell Development 14200 SE 272nd, Suite E-203 Kent, WA 98042 TRANSMITTED THIS 4th day of May, 1992 to the following: Mayor Earl Clymer Councilman Richard M. Stredicke Don Erickson, Zoning Administrator Lynn A. Guttmann, Administrator Members, Renton Planning Commission Jim Hanson, Development Services Manager Gary Gotti, Fire Marshal Ronald Nelson, Building Director Lawrence J. Warren, City Attorney Jay Covington, Mayor's Executive Assistant Transportation Systems Division Valley Daily News Utilities System Division OPursuant to Title IV, Chapter 8, Section 15 of the City's Code, request for reconsideration must be filed in writing on or before 5:00 P.M. May 18, 1992.. Any aggrieved person feeling that the decision of the 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 review of the record, take further action as he deems proper. An appeal to the City Council is governed by Title IV, Chapter 8, Section 16, 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. 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 know the contents of the communication and would allow them 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 •well as Appeals to the City Council. uses, staff recommends approval of the rezone and conoiuonal use (tyuc... 1 ERC CONDITION No. 2., is modified to read: The applicant shall, in order to address noise impacts on residential associated with the traffic on Sunset Boulevard, modify the proposal to reduce the interior noise levels of building No. 1 and No. 2 to to be approved by the Development Services Division rior tote issuance o a Buildin P . Modifications shall include such items as additional landscaping an or allditional sound insulation. • 2. ERC Condition No. 3 is deleted because differences in the topography between the two sites and an existing fence on the west side of the Summerwind site which provides adequate visual screening. 3. The applicant/owner shall, in order to address off-site recreational impacts, provide a voluntary contribution of $150.00 per unit to the Parks Recreation Mitigation Fund. 4. The applicant shall submit a material color/sample board, in order to address visual and neighborhood compatibility impacts, for Development Services Division approval, prior to the City Council public hearing on the rezone request. 5. The applicant shall, in order to address the impact of the proposal on significant existing trees to be retained, as well as proposed landscaping, provide surety devices and covenants to assure the preservation and maintenance of such landscaping for a period of at least three years. The applicant shall provide surety devices and covenants for approval by the Development Services Division prior to the issuance of Building Permit. The landscaping covenants shall specrfy the following: a) All land clearing, tree cutting and landscaping shall be installed and maintained in accordance with landscaping and pruning standards, to be approved by the Development Services \ Division prior to the issuance of a Building Permit; Cr b) Tree replacement during the three year period shall be done in accordance with the following schedule: 1) Trees and plant material less than 6 inches caliper Each tree shall be replaced with two (2) replacement trees of 2 inches caliper or larger of equivalent species. 2) trees and plant material greater than 6 inches caliper Each tree lost over 6 inches* caliper shall be replaced with two (2) trees of 2 inches caliper or larger of equivalent species, plus one (1) additional tree of similar size and species for each inch over 6 V inches in caliper of the tree lost. oFrontage improvements will be required on Sunset: curb, gutter, sidewalks, street lighting and storm drainage. A planter strip will be required between the curb and sidewalk, Existing power poles fronting the property shall be removed. OA looped water main will be required to meet fireflow requirements. 3. The City reserves the right to request the applicant to provide analysis of downstream capacity analysis on Sunset Lift Station. 4 The applicant must provide all Code required public improvements including: street improvements, water service and storm drainage (designed and constructed to Subdivision Ordinance standards). Street improvements shall be provided to the portion of NE Sunset Boulevard abutting the site, including: curbs, gutters, sidewalks, planting strip, street lighting, and undergrounding of existing power poles/wiring. Street improvements shall be designed and constructed in accordance with City Standards for Arterials Streets. 5. Utility improvement service fees (SUCC Fees) will be required to be paid to the City prior to the issuance of the building permit. 6. It is recommended that the applicant obtain certification that the site is free from hazardous materials prior to the start of construction. • 7. All other relevant codes and ordinance of the City of Renton shall be complied with. S Removal of existing trees will be subject to the requirements of the City's Land Clearing and Tree • g. p :Z o ED FFit Y"p 1__— fRpr1'II Ir ijt --- :_'-- - 'IIIJ �_'� IN•1 © I © INI- - _�.:.:----• � U INILU FRONT ELEVATION lJ _ I It : t. ...... t t (1(I h ❑ • ... _ tt—•j� ------ �� REAR ELEVATION END ELEVATION — D UNIT c a • D UUOL�DOG�]® �3 o m E J 4 --_- _--- Page tU April 14. 1992 (/Q tl )` tll q' i I' - :c.' >"•..r./.;•:�:_•,..i+,'L •'�:112�.._�_C el tt rj 2 nib _ .. •,' /OD' c° Ij I • �.. O/S1 �'r I o 1. y C' ° )>° `I� 1, Op r•n -JI I 1 t I` I r oo'` ESIDE "r° n I "A - low of 1 .r a�..e•1 1 j 1 � C) I W' /Ju �/ rU I • �I I � � a r L iI ,v.sue- s� X". Litt[ .. . i. >I �9 Ulz�:bo/77 Q RET IL `I Ll_I _ o I V� I — ; 1 c• nI GEN ! i 35. Colo Oo/O }o o•s •n�fr ti j�l BANK Ad OFFICE GZ I 1� m ( !liar RETA .00' Iil `Lr •t.S L • T— roF, t ' 0040 G&ET RE:i-9' NANO CPI O I !� N id-IDZ.•JB / c.(ICE IS 2.9' _ S •'%CFF PROP.„L1., �..,: .,r•ri rf,. /, ( � OFFICE OT 2 ' I .I. I ETA ` i o : I B— I i ra�•�tA ,� I,S7 81 1 rr•it i SS OGO °[•fe°I• .+.url ITI : I ,l° ea. 004� J °��/-jS ,• . elm ! l.,r I: I 1- � I „� `� • �• ."� rr � -�. '_ 0 h Cr i. ` :�—� .•eo 1; f e° SCvJ ^ts= '� .,. to it yLf• \•• � �y�i'T '� �-'r� >,l�°', J.''��/." 11�" 'j•1 •>:: r f)�' o - �'�+1 Inc' ' I ..1•es�' ^Z�� Y�r�.r.n•� o •l.. y, r,, ,f f� 1`a• r!f'r .i� t f!J { y.c -J'' _' t..') I All. 5,.. /• '�''' �� ;` B-1 N �!/ r v :f!/• � 4 �� '• �lr ',', � .,vim XO '. 0 1f0 � ! / �rl• 1 2 �1•� h k IIN 1 ,'•` ,' ;I r r til eL_—•e 1 j0 i r n G-1 sofa �.}... "� R-3 o .I ZONING MAP prelmrpl PRELIMINARY REPORT TO THE HEARING EXAMINER AFL rinS O',NN-O,ti ES Page 11 April 14, 1992 0 • 0 000000 0000 . .-. . . . . . .- 000000 . . . . . . . . . . . - 000000 LAND USE ELEMENT n n n n n n n o Single Family IIIIM Commercial ILELow Density Office /Office Park Multi-Family EM f Medium Density Publlc/Ouasl-Public Mulll-Famlry, High Density Light Industrial Multl-Famliy Recreallon �.�.' Heavy Industrial Greenbelt a Manufacturing Park / Multiple Option Revised April 1985 ^� COMPREHENSIVE PLAN ..Y I Z ' m m — 0 I C I ` e S o0 o O � i' � Ii � � � ri-f/r✓� I I � I I I I I —. T� � '• I I m lu r ;Iry II , r '1 m TALL PRS KtDl�G EUVATIONS ? N �N�a 2 i ! _ 7M 1A - P&TC KMfS CIS o0 t�/i11_ RR A NOT ARCHITECTS .0:. 1 8 UN 1 r N � v J aL I . N I V I v�Yv I I I x I v i ❑ lw I J ' \ l J ° I I I V I I a 1 V I I zq ZZ .GULL /� .OL.Ls.L6 1J V(,S I 1L'7U7SV�y✓l 7NJ� luS:I I \ 3.1✓"1 I 17M: , I I - I I NOTICE As of May 1 , 1992, the BuildingDepartment will be collecting fire mitigation ees on all new construcion. For your information these fees Will be collected in accordance with Council Resolution #�895. This resolution was adopted to assist in building two new fire stations, and relocating an existing station. Fees will -be calculated by the Fire Prevention Bureau. Any questions concerning the fees or this new resolution should be directed to Fire Prevention. FEES WILL BE COLLECTED AT THE TIME A PERMIT IS ISSUED. They will be: Commercial and Industrial .52/sq ft of building Fee established by Resolution #2895. Calculated by Fire Department Plans Reviewer Multi-family Units: $388/each unit Fee established by Resolution #2895. Calculated by Fire Department Plans Reviewer Single Family Residence: $488/home Fee established by Resolution #2895. NOTE: All plans which have been accepted for review prior to May 1 , 1992, will be exempt from these fees. li�►d!NS DiVIS1ON' CITY p� RENTM �1!Jr L I CITY OF RENTON GV ,F L... MEMORANDUM DATE: April 27, 1992 TO: Fred Kaufman k FROM: David Christensen SUBJECT: TALL FIRS TOWNHOMES AND BOOK/ BALES REZONE AND PRELIMINARY PLAT The purpose of this memorandum is to provide further clarification to the issue of whether sewer is available to the above referenced projects. ' The subject projects lie within the Honey Creek Sub-basin which due to non- completion of Metro's May Valley Interceptor and the City's Honey Creek Interceptor (both are currently proposed for completion in 1995) requires that it's flow be pumped to adjacent sub-basins by way of the Sunset and Devil's Elbow Lift Stations. This transfer of flows is considered temporary and, therefore, these lift station systems were not designed for full saturation development. In addition to this constraint, the Honey Creek sub-basin collection system has developed a significant increase_ in inflow and infiltration flows. The combination of these two factors has resulted in surcharge conditions in the downstream systems from the lift stations during peak wet weather flow conditions. This surcharging condition raised "red flags" by 'Wastewater staff. An in.tiai evaluation was performed to identify a strategy to quantify/qualify and recommend solutions to the surcharging condition both from a short and long term standpoint. Both of the proposed developments were initially reviewed through the environmental process midstream of our evaluation of this system. - The intention of our comments at the time were to provide warning to the applicant that a problem existed within the sub-basin in which their development lies and that they may be required to participate in a study to determine the affects their development.as well as others would have on the existing system. At this time we have completed our initial evaluation and have developed and begun to initiate a strategy that provides both a short term resolution of current restraints as • well as a long term solution to allow for saturation development of this sub-basin as will be permitted in the updated land use plan. Fred Kaufman Tall Firs Townhomes and cook/Bales Rezone and Preliminary Pla, Page 2 The short term work includes rehabilitation of the Devil's Elbow Lift Station (work completed January, 1992) and replacement of the major "bottleneck sections" of the downstream system from the Sunset Lift Station (currently in design, construction expected to be completed in the summer of 1993). These two projects will significantly reduce the likelihood of surcharging occurring. The third element to the short term solution is the Inflow and Infiltration Study which will identify critical areas in need of correction followed by construction projects that will alleviate the critical problems. We have begun the preliminary engineering work for this study. After meeting with both applicants, we believe we have identified a solution that will meet the needs of both the applicants as well as the City. What is being proposed is that both applicants make a voluntary contribution of an amount not to exceed $500/unit to the City's Wastewater Utility to be utilized on construction of repair sections identified. by the Inflow and Infiltration Study. The exact dollar amount per unit will be determined utilizing a formula acceptable to both parties that identifies the quantity of repair necessary to reduce the inflow and infiltration volume by an amount equivalent to their developed flows. This solution results in a no net gain of flows to the existing system. The long term solution for this sub-basin will be the construction of the connecting gravity fed lines of the May Valley and Honey Creek Interceptors. As was earlier stated, finalization of construction of these projects is currently anticipated for 1995. The completion of these projects will provide the capacity necessary to serve the long term needs of this sub-basin, as well as allow retirement of both the Devil's Elbow and . Sunset Lift Station. 1 realize that I have presented a lot of base information to you. The purpose of this information is to illustrate that City staff is pursuing resolution of the problem and that it was not our intention to disallow the development of the subject projects but to inform the applicant of the current status of the project and to include them in the solution. Therefore, it is the recommendation of the Wastewater Utility Section of the Planning/Building/Public Works Department that the projects be approved from a sewer availability standpoint with the condition that the applicants make a voluntary contribution 'n an :: Ount not to exceed $500/unit. With the exact amount per unit to be as determined by Wastewater staff. The total amount shall be paid prior to issuance of the applicant's Public Works construction permit. Thank you for taking the time to review this material. D:92-308:DMC:ps CC: Don Erickson _ • BUILDING PERMIT CITY OF RENTON REQUIREMENTS PLANNING/BUILDING/PUBLIC WORKS DEPARTMENT DEVELOPMENT SERVICES DIVISION COMMERCIAL'OR PHONE: 235-2540 MULTIFAMILY MULTIFAMILY, INDUSTRIAL, AND COMMERCIAL NEW CONSTRUCTION COMPLETED BUILDING PERMIT APPLICATION FOR EACH BUILDING SHALL INCLUDE: (1 1 1. Receipt for Construction Plan Review fees from Public Works Customer Service. (see construction fee schedule handout) (- 2. 2-3-4 RULE - The applicant shall submit two complete sets of plans containing architectural, structural, civil, landscaping, sprinkler, electrical, and mechanical plans, three additional sets of architectural and structural plans, and four sets of civil plans containing water, sewer, off-site improvements, sanitary sewer, storm sewer, and TESCP. 3. Where specifications supplement construction drawings, submit two copies. r 4. Stress/structural calculations are required (two copies). r Soil report, storm drainage calcs, and downstream analysis (two copies). r i 6. Energy code calculations are required. Include heat load cal culations, energy trade-off calculations, HVAC system specifications, interior & exterior power/lighting budgets, and for multi-family projects include energy code checklist. Use 1991 Washington State Energy Code. (one copy) r 1 7. An environmental impact checklist may be required - contact the Development Services Division at 235-2540 for further information. If this procees is completed or under way, include City project number. r 8. Written legal description, including tax assessor's number, on 8 1/2" x 11" paper (two copies). THE PLOT PLAN SHALL CLEARLY SHOW THE FOLLOWING: (ALL ITEMS WILL BE CHECKED BEFORE ACCEPTANCE) r 9. Scale and north arrow. r 10. Location, identification and dimensions of all buildings, property lines, streets, alleys and easements. Indicate condition of all public right-of-ways and submit verification of right to use easements. r 11. Off-street parking layouts and driveways showing circulation and paving. 12. Show new and existing curbs, gutters, sidewalks, street paving, storm drainage, and submit storm drainage calculations. r 1 13. Show fire hydrant locations (new and existing) within 300 feet of building. r 14. Show lighting and sign standards (new and existing). r`.f r 16. .Landscaped areas. r 17. Grading plan required, showing proposed and existing contours and elevations of site. GENERAL NOTES MUST INCLUDE THE FOLLOWING: (MAY BE ON COVER SHEET). F 1 18. The full name of the project. r 1 19. The name, address and telephone number of owner and agent(s). (- 120. The area, in square feet or acres, of the project site. [L 1 21. The existing zoning of the project site. [L 1 22. The seismic zone (Zone #3) of the project site. r I 23. The floor, roof and wind design loads. [L 1 24. The proposed use of the building(s) - if a multi-family dwelling, indicate number of units. [ 1 25. The 1988 UBC designation of occupancy group. r 1 26. The 1988 UBC type of construction of proposed building(s). F 1 27. The area of each building in square feet. [L 1 28. The occupancy load (maximum capacity) of each building. NOTE -- PLANS WILL NOT BE ACCEPTED FOR • A PERMIT WITHOUT THE FOREGO IN INF RMATION. ** After each department has approved the proposed construction, the required permits will be issued and the builder's copy of the approved plan turned over to the applicant. THE BUILDER'S COPY MUST BE AVAILABLE TO INSPECTORS AT THE JOB SITE AT ALL TIMES. ANY CHANGES MADE MUST BE APPROVED BY ABOVE PROCEDURES. ** Separate permits are required for, but not limited to, plumbing, electrical, septic tanks, signs, refrigeration equipment, sewer hook-ups and off-site improvements, such as sidewalks, curbs and gutters, water mains, curb cuts for driveways, storm drainage, street lighting and street signs. ** The Building Division will be responsible for the inspection and enforcement of requirements of building, plumbing, heating, electrical, occupancy, fire resistive construction, yard, area, parking, signs and any other building requirements not specifically provided for below. ** The Fire Department will be responsible for the inspection and enforcement of requirements for fire alarm systems, fire extinguishing systems, fire hydrants, fire lane access and fire exits. ** The Public Works department will be responsible for the inspection and enforcement of requirements for grade and drainage, curbs, gutters, sidewalks, access and egress from parking areas, water service, sanitary sewers, storm drainage, street lighting, and street signs. ** No new oil heating systems will be allowed in the aquifer protection areas. ** A Certificate of Occupancy will not be issued until all departments have given final approval. APPLICATION ACCEPTED BY: DATE- FRMOTZ i CITY OF RENTON PLANNING/BUILDING/PUBLIC WORKS DEPARTMENT 206-235-2631 f CONSTRUCTION FEE SCHEDULE PER ORDINANCE NO. 4345 • 1. Fill out Public Works Construction Permit Application form and attached Public Works Construction Permit Cost Breakdown form. It is required that you provide your best estimate on the cost of proposed improvements to water, wastewater, stormwater, and transportation facilities, both on-site and off-site. 2. Pay the inspection/approval fee, as determined on the attached Construction Permit Cost Breakdown form, at the 4th floor Customer Service Counter of Renton City Hall. You will be given a payment receipt. 3. Deliver a copy of the inspection/approval fee payment receipt to the 3rd floor Customer. Service Counter of Renton City Hall. • PUBLIC WORKS CONSTRUCTION PERMIT INSPECTION/APPROVAL • FEE CALCULATION WORKSHEET 50% INSPECTION/APPROVAL FEES PER ORDINANCE NO. 4345 PROJECT NAME: 1. Estimate the total cost of offsite and onsite improvements for water lines, sewer lines, stormwate facilities, and roadway improvements for your project. Enter estimated costs in items (A) through (E below. (A) Water $ (B) Sewer $ (C) Stormwater $ (Includes On-Site Pavement) (D) Roadway $ (Street, sidewalks, street lighting, etc.) ,- (E) Total Improvements $ (A) + (B) + (C) + (0) = (E) 2. Calculate 50% inspection/approval fee for total improvements, as follows: • (F) 2.5% of First $100,000 of(E) $ (G) 2% of over $100,000 but less than $200,000 of(E) $ (H) 1.5% of over $200,000 of(E) $ (1) Total 50% Inspection/Approval Fee: (F) + (G) + (H) _ (1) $ 3• Breakdown of 50% Inspection/Approval Fees is performed as follows: (J) 50% Water Fee: $ 401/343.90.00.01 (I) 50% Sewer Fee $ 401/343.W.00.02 (B) : (E) x (n = (K) (L) 50% Stormwater Fee: $ 401/343.90.00.00 (C) (E) x m = (L). • (M) 50% Roadway Fee: $ 000/343.20.00.00 (D) : (E) xm = (M) 4. Check: Make sure (n +(K) + (L) + (M) _ (1) SAMPLE CALCULATION PUBLIC WORKS CONSTRUCTION PERMIT INSPECTION/APPROVAL • FEE CALCULATION WORKSHEET 50% INSPECTION/APPROVAL FEES PER ORDINANCE NO. 4345 PROJECT NAME: XYZ Apartments 1. Estimate the total cost of offsite and onsite improvements for water lines, sewer lines, stormwater facilities, and roadway improvements for your project. Enter estimated costs in items (A) through (D) below. (A) Water $ 45,000 (B) Sewer $ 20,000 (C) Stormwater $108,000 (Includes On-Site Pavement) (D) Roadway $ 62,000 (Street, sidewalks, street lighting, etc.) (E) Total Improvements $235,000 ($45,000) + ($20,000) + ($108,000) + ($62,000) _ ($235,000) ? Calculate 50% inspection/approval fee for total improvements, as follows: (F) 2.5% of First $100,000 of(E) $ 2,500 .025 x $100,000 = $2,500 (G) 2% of over $100,000 but less than $200,000 of(E) $ 2,000 .02 x $100,000 = $2,000 (M 1.5% of over $200,000 of(E) $ 525 .015 x ($235,000 - $200,000) = $525 (1) Total 50% Inspection/Approval Fee: ($2,500) + ($2,000) + ($525) = ($5,025) $ 5,025 3. Breakdown of 50% Inspection/Approval Fees is performed as follows: (J) 50%Water Fee: $ 962.23 401/343.90.00.01 ($45,000) ; ($235,000) x ($5,025) = ($962.23) (KC) 50% Sewer Fee $ 427.66 401/343.90.00.02 ($20,000) _ ($235,000) x ($5,025) = ($427.66) (L) 50% Stormwater Fee:. $2,309.36 401/343.90.00.00 ($108,000) ($235,000) x ($5,025) _ ($2,309.36) • (M) 50% Roadway Fee: $1,325.75 000/343.20.00.00 ($62,000) ($235,000) x($5,025) _ ($1,325.75) 4. Check: ($962.23) + ($427.66) + ($2,309.36) + ($1,325.75) = $5,025 OK DETERMiNAXION OF NON-SIGNIFICANCE-MITIGATED MITIGATION " SURFS FROJECT: Tall Hrs-(ownhomes PROPONENT: Seattlp- sn i es ors APPLICATION NUMBED: ECF:R-05G-91; CU DE$CRIP T ION OF PRC?QSAL: Rezone from G-1, General Zone to R 2, Residential with a Conditional Use Permit to allow townhoUees with tnree (3) or more dwelling units in a building. LOCATIC-N OF PROPOSAL: 4k3W NE Sunset,RoulPvard UNDITIGNS: The Envirunrriental Review Committee i3ouod a Determination of Non-Significance-Mitigated Willi the fdldwirty c:ondrtions: 1. Tho applicant snali,in ordar to reduce the potential H(JVP)-Srr impacts on first responsC time Caused by:he additional demand placed on the Fire Department by the project, lkty the City of Renton Fire MiCgalion Fee in effect at the time of application for a Building Permit for each element of thr project. if no fee is In 04vt at that time,the applicant sk>all either sprinkle each residential unit 4r vcluntarlly contribute a Fire Mitigation Fop of $433 for each unsprinkled multi-family (e.g., townhouse) residential unit. 2. The applicant shall, in order to address noise Impacts on 1135idc:ritial associated with the traffic on Sunset Boulevard, modify the,proposal to roduco the interior noise levels of buildings rJo. 1 and No.2 to more than 55 db.,to be approved by the bevelopment Services Qmsion prior to the public: rearing on re201l0 and condltinngl use. MudiRcations shall Include such items as aoditional landsoaping and/or additional sound insulation. 3. T:ne applicant shall, In order to address liUht Arid glare impacts on resid.entUn from parking areas loc ated to the cast side o'1he proposal, modify the proposal io provide visual screening to reduce the night-time headlight glare Into residential buildings, to bo 'approved by the Development SFrvir.Ps Division prior to the public hearing on rezone and conditionai use. Modifications shall include such items as adrildonal lancisr-aping and/or additional visual screening Insulation, Notes to Applicant: A.. If the applicant cancels the Building Permit in writing, thsn the unencuinioor-d portion of the Fire Mitigation fee-ptus accrued interest will be refundod to the applicant. 6. Fronlago improvements will be required on Sunset: curb,gutter, sidewalks; street lighting and storm drainago. A planter strip will be required betwepo the curb-and sidewalk, 5-�dsting pnwpr poles frUnth Iy the property shall be removed. C. A looped water main will be rv<palisc}to meet fireflow requirements. D. The City reserves the right tc request the applicant to provida analysis of downstream capacity analysis on Sunset Lift Statlon. • E It is recommendeG that the applicant/owner provide:i voluntary contribution of $150.00 per unh to the Parks Recreation Mitigation Fund. F. The applicant must pruvtdr, all Code required public improvements including: street improvements, water service and storm drainage (designed and constructed to Subdivislon Oroinance standards). Street irnpiovernents shall be provided to the portion of NE Sunset Boulevard abutting the site, including: curbs, guUrs, sidewalks, plari log strip, street lighting, and undargrouriding of existing power poles/wiring. Street Improvements shall be designed and constructed in accordance with tarty Standards for Arterfals Streets. G. Utility improvement Service tees (SUGC Foes) will be required to be ;-.,Aid to the City prior tc the Issuance cf:ha b6ldhig permit. !'. It Is recommended that the applicant obtain certification that the site is free from hazardous materials prior to the start of constructlon. I. All other relevant codes and ordinance of the City of Renton shall ba complied wkth, J_ Removal of existing trees will be subject to the requirements of the Crty's Land Clearing and Tree Cutting Ordinance. mtrmPas-2 • M. OFF SITE ANALYSIS • • III. OFF-SITE ANALYSIS • A. Upstream Drainage Analysis From the site visit and existing topography map of the project, it is apparent that the site does not receive any storm drainage runoff from upstream properties. The north property line of the subject site is located at the ridge line of the land and the property to the north drains away from the project. Properties to the east and west have already been developed and contain their own storm drainage systems. The project is bounded to the south by Sunset Boulevard and does not receive any storm drainage runoff from the south due to the topography. B. Downstream Drainage Analysis Please refer to the enclosed aerial topography map for the mapping of the downstream conveyance system. The storm drainage runoff from the two existing catch basins along the north portion of Sunset Boulevard adjacent to the subject property discharges to Honey Creek by two different routes. The existing catch basin located at the east portion of the project crosses Sunset Boulevard via an existing 18-inch CMP pipe to the catch basin located at the south portion of the road and discharges to the south via an 18-inch CMP pipe. From here, the storm drainage runoff sheet flows for approximately 150 feet before discharging into Honey Creek. From this point, Honey Creek flows westerly through a wooded area for approximately 1,600 feet before reaching an existing 72" x 44" arch culvert under 138th Avenue South. • At this point, the second catch basin located at the west portion of the project discharges to Honey Creek. The second catch basin located at the west portion of the project along Sunset Boulevard is tightlined via a 12-inch pipe which travels for approximately 400 feet before reaching the intersection of Sunset Boulevard and 138th Avenue S.E. From here, storm drainage runoff changes direction and travels southerly for approximately 200 feet through a 12-inch CMP pipe and discharges to the entrance of the 72" x 44" arch culvert under 138th Avenue S.E. As mentioned above, this is the location that the storm drainage runoff from two existing catch basins adjacent to the property meet each other. From this point, storm drainage runoff travels southwesterly under an existing shopping center through a 72" x 44" arch culvert for approximately 900 feet before discharging to an open ditch located at the southwest portion of an existing McDonald's restaurant. This ditch is approximately 3 feet wide at the bottom, 10 feet wide at the top and approximately 2 to 3 feet deep. Storm drainage runoff travels approximately 200 feet before reaching Whitman Avenue and discharging through a 56" x 36" culvert, traveling westerly for approximately 500 feet before crossing Sunset Boulevard. Through our research and conversations with City officials, / we did not find any indications of erosion or flooding along this drainage course. Page 3 of 11 5025.001 [ASisdcl IV. RETENTION/DETENTION ANALYSIS AND DESIGN A. Existing Site Hydrology The existing site contains 3.2 acres of undeveloped land. The site is covered with evergreen and Douglas Fir trees and undergrowth consisting of many forms of grass and shrubs. The on-site soil is classified as Alderwood gravelly sandy loam based on the U.S. Department of Agricultural Soil Conversation Service Map. B. Developed Site Hydrology Storm runoff generated from the developed portion of the site will be collected via the storm drainage system and will be conveyed to the proposed detention vault with grass-lined swale prior to discharge to the downstream system. The proposed project provides detention and biofiltration in the form of a grass-lined swale for treatment of the on-site storm drainage prior to discharge to the downstream drainage system. Please refer to the downstream tributary area map enclosed within the report for the location delineation of the project site and downstream conveyance system. C. Hydrologic Analysis The calculation method used in sizing the detention vault is based on the items outlined within the King County Drainage Manual and City of Renton Standards. The detention system has been sized using the Waterworks software program. • Please refer to the storm drainage calculation within this section for more detail of the analysis. D. Retention/Detention System The detention system for this project has been designed to incorporate a detention vault with the flow restricted manhole to control discharge from the system. Please refer to the grading and storm drainage plan and detail to see the relation of the control manhole with the adjacent appurtenances. The volumes calculated within the storm drainage vault are based on the King County and City of Renton standards using Santa Barbara Urban Hydrograph Analysis. Page 4 of 11 - 5025.001 lasisacl i H rr�0d l06 c 50"1 to kn to Www W W W W W xxx N N Vf Don CA/ � woo a,d j=o E.sZ- ScC Br U si ) �Na aaa cNvrr �reC P f�iriOn a �n P,o _ z.gr LIZ .s �f'e �O��Or✓ /%''� CrJrn�'Uf!', `'/f'/)r''rf%�FF� C�I��CU�C,rf•J.• j:-,-,� F� \ 'S��1^J �V.^a�,�• �O ST Qeve l o,JFcl /D IG / �m yenr V/f v_.. re a = e A G• T T, G 2/25/94 Barghausen Engineers page 1 TALL FAIRS TOWNHOMES STORME DRAINAGE DETENTION CALCULATION • BASIN SUMMARY=====_______________________ BASIN ID: 1A NAME: 2YR\24HR PRE-DEV. RUNOFF SBUH METHODOLOGY TOTAL AREA. . . . . . . : 3 . 20 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 3 . 20 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 81. 00 TIME OF CONC. . . . . : 44 . 34 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 00 Acres CN. . . . . 98 . 00 TcReach - Sheet L: 300 . 00 ns: 0 . 4000 p2yr: 2 . 00 s: 0. 0650 TcReach - Shallow L: 100 . 00 ks: 3 . 00 s: 0 . 0250 PEAK RATE: 0. 18 cfs VOL: 0. 16 Ac-ft TIME: 490 min BASIN ID: 2A NAME: 10YR\24HR PRE-DEV. RUNOFF SBUH METHODOLOGY TOTAL AREA. . . . . . . : 3 . 20 Acres BASEFLOWS: 0 . 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 90 inches AREA. . : 3 . 20 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 81 . 00 TIME OF CONC. . . . . : 44 . 34 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 0. 00 Acres CN. . . . . 98 . 00 TcReach - Sheet L: 300 . 00 ns: 0. 4000 p2yr: 2 . 00 s: 0. 0650 TcReach - Shallow L: 100 . 00 ks: 3 . 00 s: 0. 0250 PEAK RATE: 0. 50 cfs VOL: 0. 33 Ac-ft TIME: 490 min BASIN ID: 3A NAME: 100YR\24HR PRE-DEV. RUNOFF SBUH METHODOLOGY TOTAL-AREA. . . . . . . : 3 . 20 Acres BASEFLOWS: 0 . 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 3 . 90 inches AREA. . : 3 . 20 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 81. 00 TIME OF CONC. . . . . : 44 . 34 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 0 .00 Acres CN. . . . . 98 . 00 TcReach - Sheet L: 300 . 00 ns: 0 . 4000 p2yr: 2 . 00 s: 0 . 0650 TcReach - Shallow L: 100 . 00 ks: 3 . 00 s: 0. 0250 PEAK RATE: 0. 92 cfs VOL: 0. 54 Ac-ft TIME: 490 min • 2/25/94 Barghausen Engineers page 2 TALL FAIRS TOWNHOMES STORME DRAINAGE DETENTION CALCULATION • ____________________________BASIN SUMMARY=====_______________________ BASIN ID: 4A NAME: 2YR\24HR POST-DEV.RUNOFF SBUH METHODOLOGY TOTAL AREA. . . . . . . : 3 . 20 Acres BASEFLOWS: 0 . 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 1 . 30 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 81. 00 TIME OF CONC. . . . . : 6 . 30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 1. 90 Acres CN. . . . . 98 . 00 PEAK RATE: 1. 04 cfs VOL: 0. 35 Ac-ft TIME: 470 min BASIN ID: 5A NAME: 10YR\24HR POST-DEV.RUNOFF SBUH METHODOLOGY TOTAL AREA. . . . . . . : 3 . 20 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 90 inches AREA. . : 1 . 30 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 81 . 00 TIME OF CONC. . . . . : 6 . 30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 1. 90 Acres CN. . . . . 98 . 00 PEAK RATE: 1 . 71 cfs VOL: 0. 56 Ac-ft TIME: 470 min BASIN ID: 6A NAME: 100YR\24HR POST-DEV. RUNOFF SBUH METHODOLOGY TOTAL AREA. . . . . . . : 3 . 20 Acres BASEFLOWS: . 0 . 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 3 . 90 inches AREA. . : 1 . 30 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 81 . 00 TIME OF CONC. . . . . : 6 . 30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 1. 90 Acres CN. . . . . 98 . 00 PEAK RATE: 2 . 49 cfs VOL: 0. 80 Ac-ft TIME: 470 min • 2/25/94 Barghausen Engineers page 3 TALL FAIRS TOWNHOMES STORME DRAINAGE DETENTION CALCULATION HYDROGRAPH SUMMARY PEAK TIME VOLUME HYD RUNOFF OF OF Contrib NUM RATE PEAK HYDRO Area cfs min. cf-AcFt Acres --------------------------------------------- --------------------------------------------- 1 0 . 184 490 7022 cf 3 . 20 2 0 . 499 490 14370 cf 3 . 20 3 0 . 917 490 23670 cf 3 . 20 4 1. 042 470 15091 cf 3 . 20 5 1. 707 470 24244 cf 3 . 20 6 2 . 487 470 34896 cf 3 . 20 7 0. 184 790 15091 cf 3 . 20 8 0 . 499 540 24244 cf 3 . 20 9 0 . 917 520 34896 cf 3 . 20 • 2/25/94 Barghausen Engineers page 4 TALL FAIRS TOWNHOMES STORME DRAINAGE DETENTION CALCULATION STAGE STORAGE TABLE RECTANGULAR VAULT ID No. 1 Description: DETENTION VAULT Length: 100 . 00 ft. Width: 20. 00 ft. STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- 403.83 0.0000 0.0000 405.10 2540 0.0583 406.40 5140 0.1180 407.70 7740 0.1777 403.90 140.00 0.0032 405.20 2740 0.0629 406.50 5340 0.1226 407.80 7940 0.1823 404.00 340.00 0.0078 405.30 2940 0.0675 406.60 5540 0.1272 407.90 8140 0.1869 404.10 540.00 0.0124 405.40 3140 0.0721 406.70 5740 0.1318 408.00 8340 0.1915 404.20 740.00 0.0170 405.50 3340 0.0767 406.80 5940 0.1364 408.10 8540 0.1961 404.30 940.00 0.0216 405.60 3540 0.0813 406.90 6140 0.1410 408.20 8740 0.2006 404.40 1140 0.0262 405.70 3740 0.0859 407.00 6340 0.1455 408.30 8940 0.2052 404.50 1340 0.0308 405.80 3940 0.0904 407.10 6540 0.1501 408.40 9140 0.2098 404.60 1540 0.0354 405.90 4140 0.0950 407.20 6740 0.1547 408.50 9340 0.2144 404.70 1740 0.0399 406.00 4340 0.0996 407.30 6940 0.1593 408.60 9540 0.2190 404.80 1940 0.0445 406.10 4540 0.1042 407.40 7140 0.1639 408.70 9740 0.2236 404.90 2140 0.0491 406.20 4740 0.1088 407.50 7340 0.1685 . 405.00 2340 0.0537 406.30 4940 0.1134 407.60 7540 0.1731 2/25/94 Barghausen Engineers page 5 TALL FAIRS TOWNHOMES STORME DRAINAGE DETENTION CALCULATION STAGE DISCHARGE TABLE MULTIPLE ORIFICE ID No. 1 Description: MULTIPLE ORIFICE CONTROL ST Outlet Elev: 403 . 83 Elev: 401. 83 ft Orifice Diameter: 2 . 0889 in. Elev: 406. 33 ft Orifice 2 Diameter: 3 . 5742 in. Elev: 407 . 13 ft Orifice 3 Diameter: 2 . 6367 in. STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> (ft) ---CfS-- ------- (ft) ---cfS-- ------- (ft) ---CfS-- ------- (ft) ---cfS-- ------- 403.83 0.0000 405.10 0.1334 406.40 0.2815 407.70 0.7812 403.90 0.0313 405.20 0.1386 406.50 0.3364 407.80 0.8107 404.00 0.0488 405.30 0.1436 406.60 0.3772 407.90 0.8388 404.10 0.0615 405.40 0.1484 406.70 0.4115 408.00 0.8658 404.20 0.0720 405.50 0.1530 406.80 0.4417 408.10 0.8917 404.30 0.0812 405.60 0.1575 406.90 0.4692 408.20 0.9168 404.40 0.0894 405.70 0.1619 407.00 0.4946 408.30 0.9410 404.50 0.0969 405.80 0.1662 407.10 0.5183 408.40 0.9645 404.60 0.1039 405.90 0.1704 407.20 0.5906 408.50 0.9874 404.70 0.1104 406.00 0.1744 407.30 0.6398 408.60 1.0097 • 404.80 0.1166 406.10 0.1784 407.40 0.6804 408.70 1.0314 404.90 0.1225 406.20 0.1823 407.50 0.7166 405.00 0.1281 406.30 0.1861 407.60 0.7499 • 2/25/94 Barghausen Engineers page 6 TALL FAIRS TOWNHOMES STORME DRAINAGE DETENTION CALCULATION LEVEL POOL TABLE SUMMARY MATCH INFLOW -STO- -DIS- <-PEAK-> STORAGE <--------DESCRIPTION---------> (cfs) (cfs) --id- --id- <-STAGE> id VOL (cf) ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- 2YR\24HR ROUTING ............. 0.18 1.04 1 1 406.24 7 4812.68 10YR\24HR ROUTING ............ 0.50 1.71 1 1 407.02 8 6374.48 100YR\24HR ROUTING ........... 0.92 2.49 1 1 408.20 9 8741.46 • LEGEND Hyd No. 1_ 0 0 M u t �0 0 �N 0 0 3 6 9 12 18 21 24 27 30 Tine in Hours Hyd No. : 1 Rate: 0 . 18 cfs Time: 8 . 17 hr Vol 0 . 16 Ac-ft Int: 10. 00 min IECEND Hyd No. 2 0 0 M u c �0 0 +�N lr 0 0 3 6 9 12 15 lE 21 24 27 30 in Tine in Hours Hyd No. : 2 Rate: 0 . 50 cfs Time: 8 . 17 hr Vol 0 . 33 Ac—ft Int: 10. 00 min • LEGEND Hyd No. 3_ 0 0 n a w u M0 0 yN A 0 0 3 6 9 12 fS 18 21 24 27 30 in Time in Hours Hyd No. : 3 Rate: 0 . 92 cfs Time: 8 . 17 hr Vol 0 . 54 Ac—ft Int: 10 . 00 min 0 a LEGEND . Hyd No, 4 u t 44o uo • 3 6 9 12 15 IE 21 24 27 Time in Hours Hyd No. : 4 Rate: 1. 04 cfs Time: 7 . 83 hr Vol 0 . 35 Ac-ft Int: 10 . 00 min 0 M LEGEND • Nyd No. 6_ 0 0 wN u c m 0 0 0 bob- 3 6 9 12 15 lE 21 24 27 Time in Hours Hyd No. : 6 Rate: 2 . 49 cfs Time: 7 . 83 hr Vol 0. 80 Ac—ft Int: 10. 00 min • IEGENU • Hyd No, 7 0 0 M w U C "0 0 +�N 0 0 0 w 6 12 fS24 30 36 42 Time in Hours Hyd No. : 7 Rate: 0 . 18 cfs Time: 13 . 17 hr Vol 0 . 35 Ac-ft Int: 10 . 00 min 7 LEGEND Hyd No, 8 0 0 h u t �0 0 a . yH 0 0 w 6 12 fS2'1 30 36 42 Time in Hours Hyd No. : 8 Rate: 0. 50 cfs Time: 9 . 00 hr Vol 0. 56 Ac—ft Int: 10 . 00 min OLT a a A N �� ' y w.r��/A��'1�1�1 KING COUNTY, W ASHINGTON, SURFACE WATER DESIGN MANUAL FIGURE 3.5.1E 10-YEAR 24-HOUR ISOPLUVIALS • 21 -- --- - - � Ydl,- =� - � - - - - ------ - - - -- `--- 22 - 23 y� - 24 11 / ✓ 2 6 _ rtlyr 28 .29 30 j - '-, .•, me rV.f 2 -s � �\. 4: - _ - -4- - - I /` Q . 1 - Gam••' f / INC _ o _ / I - 10-YEAR 24-HOUR PRECIPITATION ;5 •3.4�' ISOPLUVIALS OF 10-YEAR 24-HOUR TOTAL PRECIPITATION IN INCHES 3O - 3 •G 0 1 2 3 4 5 6 7 8 Mlles :1 lei! ems• - 1:300,000 3.5.1-10 3�� 1/90- 4.0 1 . Rely •ter.� �� �!• ��, � � �► mat kit NJ VA Owl won i�/�t'rl�� � KING COUNTY, WASHINGTON, SURFACE WATE-R DESIGN MANUAL TABLE 3.5.213 SCS WESTERN 1VASHINGTON RUNOFF CURVE NUMBERS SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS (Published by SCS in 1982) Runoff curve numbers for selected agricultural, suburban and urban land use for Type 1A rainfall distribution, 24-hour storm duration. CURVE NUMBERS BY HYDROLOGIC SOIL GROUP LAND USE DESCRIPTION A B C D Cultivated land(1): winter condition 86 91 94 95 Mountain open areas: low growing brush and grasslands 74 82 89 92 Meadow or pasture: 65 78 85 89 Wood or forest land: undisturbed or older second Growth 42 64 76 81 Wood or forest land: young second growth or brush 55 72 81 86 Orchard: with cover crop 81 88 92 94 Open spaces, lawns, parks, golf courses, cemeteries, landscaping. good condition: grass cover on 75% or more of the area 68 80 86 90 fair condition: grass cover on 50% to 75% of the area 77 65 90 92 Gravel roads and parking lots 76 85 89 91 Dirt roads and parking lots 72 82 87 89 Impervious surfaces, pavement, roofs, etc. 98 98 99 98 Open water bodies: lakes, wetlands, ponds, etc. 100 100 100 100 Single Family Residential (2) Dwelling Unit/Gross Acre % Impervious (3) 1.0 DU/GA 15 Separate curve number 1.5 DU/GA 20 shall be selected 2.0 DU/GA 25 for pervious and 2.5 DU/GA 30 impervious portion 3.0 DU/GA 34 of the site or basin 3.5 DU/GA 38 4.0 DU/GA 42 4.5 DU/GA 46 5.0 DU/GA 48 5.5 DU/GA 50 6.0 DU/GA 52 6.5 DU/GA 54 7.0 DU/GA 56 Planned unit developments, impervious condominiums, apartments, must be computed commercial business and industrial areas. (1) For a more detailed description of agricultural land use cure numbers refer to Nationai Eng^eering Handbook, Section 4, Hydrology, Chapter 9, August 1972. (2) Assumes roof and driveway runoff is directed into street%storm system. (3) The remaining pervious areas (lawn) are considered to be in good condition for these curve r'umbers. CYD 3.5.2-3 .11;92 KING COUNTY, WASHINGTON, SURFACE WATER _DESIGN MANUAL (2) CN values can be area weighted when they apply to pervious areas of similar CN's (within 20 CN points). However, high CN areas should not be combined with low CN areas (unless the • low CN areas are less than 15% of the subbasin). In this case, separate hydrographs should be generated and summed to form one hydrograph. FIGURE 3.5.2A HYDROLOGIC SOIL GROUP OF THE SOILS INKING COUNTY HYDROLOGIC HYDROLOGIC SOIL GROUP GROUP* SOIL GROUP GROUP* Alderwood C Orcas Peat D Arents, Alderwood Material C Oridia D Arents, Everett Material B Ovall C Beausite C Pilchuck C Bellingham D Puget D Briscot D Puyallup B Buckley D Ragnar B Coastal Beaches Variable Renton D Earimont Silt Loam D Riverwash Variable Edgewick C Sala[ C Everett A/B `Sammamish D Indianola A Seattle D Kitsap C Shacar D Klaus C Si Silt C Mixed Alluvial Land Variable Snohomish D Neilton A Sultan C Newberg B Tukwila D Nooksack C Urban Variable • Normal Sandy Loam D Woodinville D I HYDROLOGIC SOIL GROUP CLASSIFICATIONS i A. (Low runoff potential). Soils having high infiltration rates, even when thoroughly wetted, and consisting � chiefly of deep, well-to-excessively drained sands or gravels. These soils have a high rate of water transmission. I B. (f loderately low runoff potential). Soils having moderate infiltration rates when thoroughly wetted, and consisting chiefly of moderately fine to moderately coarse textures. These soils have a moderate rate of water transmission. I C. (Moderately high runoff potentiai). Soils having slow infiltration rates when thoroughly wetted, and consisting chiefly of soils with a layer that impedes downward movement of water, or soils with moderately fine to fine textures. These soils have a slow rate of water transmission. i D. (High runoff potential). Soils having very slow infiltration rates when thoroughly wetted and consisting chiefly of clay soils with a high swelling potential, soils with a permanent high water table, soils with a hardpan or clay layer at or near the surface, and shallow soils over nearly impervious material. These soils have a very slow rate of water transmission. i Frcm SCS, TR-55, Second Edition, June 19M, Exhibit A-1. Revisions made from SCS, Soil Interpretation Record, Form #5, September 1988. • 3.5.2-2 I 1/9_2 • V. CONVEYANCE SYSTEM DESIGN AND ANALYSIS • • V. CONVEYANCE SYSTEM DESIGN ANALYSIS The on-site conveyance system is sized based on calculations using the new King County Surface Design Manual. The storm drainage conveyance system has been designed for the 25-year Seattle/Renton curve. Please refer to the attached calculation. • Page 5 of 11 5025.001 [As/sdcl PIPE SIZING DRAINAGE AREA MAP BARGHAUSEN CONSULTING ENGINEERS - PIPE FLM4 CALCULATOR A = Contributing Area <Ac> Qd = Design Flow (cf's> using the Rational Method & Manning Formula C = Runoff Coefficient Qf = Full Capacity Flow <cfs> SEATTLE-RENTON 25 YEAR STORM Tc = Time of Concentration <,nin> Vd = Velocity at. Design Flow <fps> I = Intensity at Tc <in/hr> Vf = Velocity at Full Flow <fps> DEFAULT C= 0.80 n= 0.012 d= 12 Tc= 10.0 d = Diameter of Pipe <in'> s = Slope •4F pipe (N) Note: Get default values before entering data. L = Length of Pipe <ft> n = Manning Roughness Coefficient D = Water Depth at Qd <in) Tt = Travel Time at Vd <min> .JOB # 5025 JOB NAME: TALL FIRS TOWNHOUSES FROM TO A s L d Tc n C SUM R R*C SUM R*C I Qd Q+' Qd.'Gtf X D/d D of vd/VF Vd Tt C68 CB7 0.51 2.13 108.0 12 10.0 0.012 0.80 0.51 0.41 0.41 2.00 0.82 5.63 0.145 0.'40 0.256 3.07 7.18 0.707 5.07 0.35 C87 CB6 0.34 4.45 87.0 12 10.4 0.012 0.80 0.85 0.27 0.68 1.97 1.34 8.14 0.165 0.260 0.272 3.26 10.37 0.736 7.63 0.19 CB6 C55 0.40 7.28 43.0 12 10.5 0.012 0.80 1.25 0.32 1.00 1.95 1.96 10.41 0.188 0.230 0.290 3.48 13.27 0.763 10.12 0.07 C65 CB4 0.08 1.80 65.0 12 10.6 0.012 0.80 1.33 0.06 1.06 1.95 2.08 5.18 0.401 0.440 0.441 5.29 6.60 0.946 6.24 0.17 C69 CB1O 0.24 2.14 79.0 12 10.0 0.012 0.80 0.24 0.19 0.19 2.00 0.38 5.54 0.068 0.160 0.177 2.13 7.19 0.555 4.06 0.32 CB10 CS11 0.15 2.31 89.0 12 10.3 0.012 0.80 0.39 0.12 0.31 1.97 0.62 5.86 0.105 0.220 0.220 2.64 7.47 0.645 4.82 0.31 CB11 CB4 0.13 8.40 40.0 12 10.6 0.012 0.80 0.57 0.14 0.46 1.95 0.89 11.18 0.079 0.180 0.189 2.27 14.25 0.587 8.36 0.08 CB4 VAULT 0.06 4.00 25.0 12 10.8 0.012 0.80 0.05 0.05 1.52 1.94 2.94 7 .72 0.381 0.420 0.428 5.13 9.83 0.933 9.17 0.05 YD CB12 0.33 2.00 100.0 6 10.0 0.012 0.80 0.33 0.26 0.25 2.00 0.53 0.86 0.614 0.560 0.573 3.44 4.38 1.054 4.52 0.36 CB12 VAULT 0.56 2.00 2.0 12 10.4 0.012 0.80 0.89 0.45 0.71 1.97 1.40 5.46 0.257 0.340 0.346 4.15 5.95 0.837 5.82 0.01 BIOFILTRATION SWALE SIZING CALCULATIONS Trapezoidal Channel Analysis & Design Open Channel - Uniform flow Worksheet Name: TALL FIRS TOWN HOMES Comment : GRASS LINE SWALE SIZING CALCULATION Solve For Bottom Width Given Input Data: Left Side Slope. . 3.00: 1 (H:V ) Right Side Slope. 3.00: 1 (H:V ) Manning's n. . . . . . 0.350 Channel Slope. . . . 0.0200 ft/ft Depth. . . . . . . . . . . . 0.33 ft Discharge. . . . . . . . 0. 18 cfs Computed Results: Bottom Width. . . . 1 .45 ft Velocity. . . . . . . . . 0.22 fps Flow Area. . . . . . . . 0.80 sf Flow Top Width. . , 3.43 ft Wetted Perimeter. 3.53 ft Critical Depth. . . 0.07 ft • Critical Slope. . . 4.5070 ft/ft Froude Number. . . . 0.08 ( flow is Subcritical ) Open Channel Flow Module , Version 3.41 (c ) 1991 Haestad Methods , Inc. * 37 Brookside Rd * Waterbury, Ct 06708 Trapezoidal Channel Analysis & Design Open Channel - Uniform flow Work sheet Name: TALL FIRS TOWN HOMES Comment : GRASS LINE SWALE SIZING CALCULATION Solve For Depth Given Input Data : Bottom Width. . . . . 4.00 ft Left Side Slope. . 3.00. 1 (H:V ) Right Side Slope. 3.00: 1 (H:V) Manning' s n. . . . . . 0.350 Channel Slope. . . . 0.0200 ft/ft Discharge. . . . . . . . 0. 18 cfs Computed Results : Depth. . . . . . . . . . . . 0.20 ft Velocity. . . . . . . . . 0. 19 fps Flow Area. . . . . . . . 0.95 sf Flow Top Width. . . S.23 ft Wetted Perimeter. 5.30 ft Critical Depth. . . 0.04 ft Critical Slope. . . S.3219 ft/ft Froude Number. . . . 0.08 ( flow is Subcritical ) Open Channel Flow Module, Version 3.41 ( c ) 1991 Haestad Methods , Inc. * 37 Brookside Rd * Waterbury , Ct 06708 VI. SPECIAL REPORT STUDY i i • Page 6 of 11 5025.001 [AS/sdc] OEOTECH CONSULTANTS, INC. May 1 6 , 1991 13256 N.E.20th St.(Northup Way),Suite 16 Bellevue,wA 98005 ,1 N 91148 (206)747-5618 PAX747-85615eattl e-Renton Investors 27400 Southeast 132nd Street , Suite F-206 Kent , Washington 98042 Attention : Ron Tremaine Subject : Geotechnical Engineering Study Proposed Tall Firs Townhouse Development 4802 - 4816 Northeast Sunset Boulevard Renton , Washington Gentlemen : We are pleased to present this geotechnical engineering report for the proposed townhouse development to be constructed on Northeast Sunset Boulevard in Renton , Washington . The purpose of our work was to explore site surface and subsurface conditions and to provide general earthwork recommendations and design criteria for foundations , retaining walls , and pavements . The work was authorized by your acceptance of our proposal , P-9513 dated April 29 , 1991 . The subsurface conditions of the proposed building site were explored with seven test pits . The explorations encountered • medium-dense to dense , glacial till and/or gravelly sand soils at relatively shallow depths . These native soils can be relied upon to support the proposed buildings founded on conventional footings . However , the glacial till soils are silty and thus are very moisture sensitive . It would be advantageous to perform earthwork during the normally dry summer months . If earthwork is performed during extended periods of wet weather , imported pit-run gravel may be needed for structural fill and as a protective covering for access roads and bearing surfaces . The attached report contains a discussion of the study and our recommendations . if there are any questions , or if we can be of further service , please contact us . Respectfully submitted , GEOTECH CONSULTANTS , INC . J D. Robert Ward Geotechnical Engineer • GEOTECHNICAL ENGINEERING STUDY PROPOSED TALL FIRS TOWNHOUSE DEVELOPMENT 4802 - 4816 NORTHEAST SUNSET BOULEVARD RENTON , WASHINGTON This report presents the findings and recommendations of our geotechnical engineering study for the site of the proposed Tall Firs Townhouse Development in Renton . The general location of the site is illustrated on the Vicinity Map, Plate 1 . Based on a building location plan furnished to us prior to our explorations and a topographic/site grading plan furnished to us following our explorations , we anticipate that the development will consist of nine townhouse buildings located throughout the site . Six of the buildings will have a slab- on-grade finish floor , and cuts of up to seven feet are proposed to reach the finish floor elevation . The remaining three buildings will have a suspended-wood finish floor over a crawl space , and the finish floor elevations will be approximately two to five feet above the existing ground surface . Much of the area around the buildings will be paved , and vehicle access to the site will be from Northeast Sunset • Boulevard on the south side . SITE CONDITIONS SURFACE The tract is somewhat rectangular in shape , except that the west side is approximately 459 feet in length and the east side is 359 feet . It has approximately 314 feet of frontage on the south border along Northeast Sunset Boulevard and is located in the northeast portion of Renton . The highest elevation of the site is approximately 430 feet at the northern edge , near the middle . From that point the site slopes gently to the south , east , and west , except for some moderate slopes on the western portion . The southern one- third of the site is relatively flat . There are three existing houses on the south end of the property which are constructed over crawl spaces . The vegetation surrounding the houses consists of grasses and occasional fir trees . The vegetation north of the houses and on the east portion of the site also consists of grasses , but the fir trees are more dense; the vegetation on the west portion , north of the houses , consists of brush with fir , alder , and maple trees . • GEOTECH CONSULTANTS , INC. Seattle-Renton Investors JN 91148 • May 16 , 1991 Page 2 The adjacent properties to the north and south of the site are undeveloped . The adjacent property to the west is developed with commercial and retail buildings and is one to five feet higher than the western edge of the subject site because fills were added . The adjacent property to the east is developed with single-family residences and is near the same elevation as the eastern side of the subject site . SUBSURFACE The subsurface conditions were explored by seven test pits at the approximate locations shown on the Soils Exploration Plan , Plate 2 . The field exploration program was based upon the proposed construction and required design criteria , site topography and access , subsurface conditions revealed during excavation , the scope of work outlined in our proposal , and time and budget constraints . The test pits were excavated on May 3 , 1991 with a rubber- tired backhoe owned and operated by Evans Brothers Excavating . A geotechnical engineer from our staff observed the excavation • process , logged the test pits , and obtained representative samples of the soils encountered . "Grab" samples of selected subsurface soils were collected from the backhoe bucket . The Test Pit Logs are attached to this report as Plates 3 through 6 . The uppermost soils generally consist of approximately four to five feet of loose to medium-dense, weathered glacial till which is comprised of gravelly, silty sand . The weathered glacial till is generally underlain by medium-dense to very dense , gray glacial till to a maximum explored depth of nine feet . However , in Test Pits 4 and 6 , the uppermost soils consist of four to six feet of loose to medium-dense , very gravelly sand . The final logs represent our interpretations of the field logs and laboratory tests . The stratification lines on the logs represent the approximate boundary between soil types at the exploration locations . In actuality, the transition between soil types may be gradual . The relative densities and moisture descriptions indicated on the test pit logs are interpretive descriptions based on the conditions observed during excavation . The logs should be reviewed for specific subsurface information at the locations tested . • GEOTECH CONSULTANTS , INC . Seattle-Renton Investors JN 91148 May 16 , 1991 Page 3 GROUNDWATER Groundwater seepage was observed at a depth of four feet in Test Pit 4 . The test pit was left open only for a short time therefore, the seepage levels on the logs represent the location of transient water seepage and may not be the location of the static groundwater level . It should be noted that groundwater levels vary seasonally with rainfall and other factors . We anticipate that perched groundwater could be found on the dense glacial till soil within the near surface weathered soil or gravelly sand soil . CONCLUSIONS AND RECOMMENDATIONS GENERAL Soils on this site are predominantly glacial tills . Glacial till soils have an average silt content of about 30 percent which makes them difficult to grade and compact if the soil becomes wet . This soil type is the predominate soil in the Puget Sound area with the exception of the river valley and coastal flat areas . Therefore , earth construction operations on this site are subject to the same constraints as the earthwork construction operations on most sites in the area . The constraints affect the economics of site development , but not the engineering feasibility of development under any weather conditions . CONVENTIONAL FOUNDATIONS The proposed structure can be supported on conventional continuous and spread footings bearing on undisturbed , competent glacial till or gravelly sand soils , or on structural fill placed above these competent soils . The upper weathered soils are loose to medium-dense and exceeded the optimum moisture content during our exploration . If the weathered soils are near the optimum moisture content at the time of foundation construction , then they should be compacted , and the footings may be placed on them. However , if the weathered soils are wet and not compactible , they should be removed and the footings placed on the dense, unweathered glacial till or gravelly sand . Continuous and individual spread footings should have minimum widths of • GEOTECH CONSULTANTS , INC . Seattle-Renton Investors JN 91148 May 16 , 1991 Page 4 twelve ( 12) and sixteen ( 16 ) inches and should be bottomed at least twelve ( 12) inches below the lowest adjacent finish ground surface. As noted above, some overexcavation may be needed below footings to expose competent native soils . Unless lean concrete is used to fill the overexcavated hole, the overexcavation must be at least as wide at the bottom as the sum of the depth of the overexcavation and the footing width . For example , an overexcavation extending two feet below the bottom of a three-foot-wide footing must be at least five feet wide at the base of the excavation . Footings constructed according to the above recommendations may be designed for an allowable soil bearing pressure of two thousand (2000 ) pounds per square foot (psf ) . If footings are extended down to unweathered glacial till , a bearing capacity of five thousand (5000 ) psf may be assumed . A one-third increase in this design bearing pressure may be used when considering short-term wind or seismic loads . For the above design criteria , it is anticipated that total post- construction settlement of footings founded on competent , native soils or on structural fill up to five (5) feet in • thickness) will be about one-half inch , with differential settlements of less than one-half inch . Lateral loads due to wind or seismic forces may be resisted by friction between the foundations and the bearing soils , or by passive earth pressure acting on the vertical , embedded portions of the foundations . For the latter condition , the foundations must either be poured directly against relatively level , undisturbed soil or level structural fill must be placed around the outside of the foundation . We recommend the following design values be used for the foundation ' s resistance to lateral loading : Design Parameter Value Coefficient of Friction 0 . 45 Passive Earth Pressure 400 pcf • GEOTECH CONSULTANTS , INC . Seattle-Renton Investors JN 91148 May 16 , 1991 Page 5 Where : ( 1 ) Pcf is pounds per cubic foot (2 ) Passive earth pressure is computed using the equivalent fluid density . If the ground in front of the foundation is loose or sloping , the passive earth pressure given above will not be appropriate . We recommend that a safety factor of at least 1 . 5 be used for design of the foundation ' s resistance to lateral loading . SEISMIC CONSIDERATIONS The site is located within Seismic Zone 3 as illustrated on Figure No . 2 of the 1988 Uniform Building Code (UBC) . In accordance with Table 23-1 of the 1988 UBC , the site soil profile is best represented by Profile Type S1 . SLABS-ON-GRADE • Slab-on-grade floors may be constructed atop native soils or structural fill . The subgrade soils must be in a firm, non- yielding condition at the time of slab construction . Any soft areas encountered should be excavated and replaced with select imported structural fill . All slabs-on-grade should be underlain by a capillary break layer consisting of a minimum four (4) inch thickness of free- draining granular structural fill with a gradation similar to that discussed later in PERMANENT FOUNDATION AND RETAINING WALLS . In areas where the passage of moisture through the slab is undesirable , a vapor barrier such as a 6-mil plastic membrane should be placed beneath the slab. Additionally , sand should be used in the fine grading process to reduce damage to the vapor barrier and to provide uniform support under the slab . PERMANENT FOUNDATION AND RETAINING WALLS Retaining walls backfilled on one side only should be designed to resist lateral earth pressures imposed by the soils retained by these structures . The following recommended design parameters are for walls less than twelve ( 12) feet in height which restrain level backfill : s GEOTECH CONSULTANTS , INC . Seattle-Renton Investors JN 91148 . May 16 , 1991 Page 6 Design Parameter Value Active Earth Pressure* 35 pcf Passive Earth Pressure 400 pcf Coefficient of Friction 0 . 45 Soil Unit Weight 135 pcf Where : 1 ) Pcf is pounds per cubic foot 2) Active and passive earth pressures are computed using equivalent the fluid densities . * For restrained walls which cannot deflect at least 0 . 002 times the wall height , a uniform lateral pressure of one hundred ( 100 ) psf should be added to the active equivalent fluid pressure . The values given above are to be used for design of permanent foundation and retaining walls only . The passive pressure given is appropriate only for the depth of level structural fill placed in front of a retaining or foundation wall . An appropriate safety factor should be applied when designing the walls . We recommend using a factor of safety of at least 1 . 5 for overturning and sliding . The above design values do not include the effects of any hydrostatic pressures behind the walls and assume that no surcharge slopes or loads will be placed above the walls . If these conditions exist, then those pressures should be added to the above lateral pressures . Also , if sloping backfill is desired behind the walls , then we will need to be given the wall dimensions and slope of the backfill in order to provide the appropriate design earth pressures . Heavy construction equipment should not be operated behind retaining and foundation walls within a distance equal to the height of the wall , unless the walls are designed for the additional lateral pressures resulting from the equipment . Placement and compaction of retaining wall backfill should be accomplished with hand-operated equipment . • GEOTECH CONSULTANTS , INC . Seattle-Renton Investors JN 91148 • May 16 , 1991 Page 7 Retaining Wall Backfill Backfill placed within eighteen ( 18) inches of any retaining or foundation walls should be free-draining structural fill containing no organics . This backfill should contain no more than five (5 ) percent silt or clay particles and have no particles greater than four (4) inches in diameter . The percentage of particles passing the No . 4 sieve should be between 25 and 70 percent . (Due to their high silt content , if the native sand soils are used as backfill , a drainage composite , such as Miradrain or Enkadrain , should be placed against the retaining walls . The drainage composites should be hydraulically connected to the foundation drain system. ) The purpose of these backfill requirements is to assure that the design criteria for the retaining wall are not exceeded because of a build-up of hydrostatic pressure behind the wall . The top foot to eighteen inches of the backfill should consist of a relatively impermeable soil or topsoil , or the surface should be paved . The sub- section entitled GENERAL EARTHWORK AND STRUCTURAL FILL contains recommendations regarding placement and compaction of structural fill behind retaining and foundation walls . EXCAVATIONS AND SLOPES In no case should excavation slopes be greater than the limits specified in local , state , and national government safety regulations . Temporary cuts up to a height of four (4) feet deep in unsaturated soils may be made vertical . For temporary cuts having a height greater than four (4) feet , the cut should have an inclination no steeper than 1 : 1 (Horizontal :Vertical ) from the top of the slope to the bottom of the excavation . All permanent cuts into native soils should be inclined no steeper than 2 : 1 (H :V) . Fill slopes should not be constructed with an inclination greater than 2 : 1 (H :V) . It is important to note that the gravelly sand soil may cave suddenly, and without warning . The contractors should be made aware of this potential hazard . Water should not be allowed to flow uncontrolled over the top of any temporary or permanent slope . Disturbed slopes should be covered with plastic during wet weather to minimize the GEOTECH CONSULTANTS , INC . Seattle-Renton Investors JN 91148 • May 16 , 1991 Page 8 potential for erosion . All permanently exposed slopes should be seeded with an appropriate species of vegetation to reduce erosion and improve stability of the surficial layer of soil . DRAINAGE CONSIDERATIONS We recommend the use of footing drains at the base of all footings and backfilled earth retaining walls . These drains should be surrounded by at least six (6) inches of one-inch- minus washed rock wrapped in non-woven geotextile filter fabric (Mirafi 140N , Supac 4NP, or similar material ) . At the highest point, the perforated pipe invert should be at least as low as the bottom of the footing or the crawl space , and it should be sloped for drainage . All roof and surface water drains must be kept separate from the foundation drain system. A typical drain detail is attached to this report as Plate 9 . Groundwater was observed In Test Pit 4 during our field work . Seepage into planned excavations is possible , and if encountered should be drained away from the site by use of drainage ditches , perforated pipe or French drains , or by pumping from sumps interconnected by shallow connector trenches at the bottom of the excavation . The excavation and site should be graded so that surface water is directed off the site and away from the tops of slopes . Water should not be allowed to stand in any area where foundations , slabs , or pavements are to be constructed . Final site grading in areas adjacent to building(s) should be sloped at least two (2 ) percent away from the building , except where the area is paved . PAVEMENT AREAS All pavement sections may be supported on native soils or structural fill , provided these soils can be compacted to 95 percent density and are stable at the time of construction . We recommend that a contingency be put in the construction budget for the placement of six (6) inches of select pit-run gravel in the parking areas and twelve ( 12) inches in the heavy traffic areas . Recommendations on the composition of the select pit-run gravel are included in the GENERAL EARTHWORK AND STRUCTURAL FILL SECTION . Additional pit-run and/or fabric may be needed to stabilize soft , wet or unstable areas . We recommend using Supac 5NP , manufactured by Phillips Petroleum Company, or a non-woven fabric with • GEOTECH CONSULTANTS , INC . Seattle-Renton Investors JN 91148 • May 16 , 1991 Page 9 equivalent strength and permeability characteristics . The subgrade should be evaluated by Geotech Consultants , Inc . after the site is stripped and cut to grade . The upper twelve ( 12) inches of pavement subgrade should be compacted to at least 95 percent of the ASTM D-1557-78 maximum density . Below this level , a compactive effort of 90 percent would be adequate . All subgrade areas must also be in a stable , non- yielding condition prior to paving . The pavement section for lightly loaded traffic and parking areas should consist of two (2) inches of asphalt concrete (AC) over four (4) inches of crushed rock base (CRB) or three (3) inches of asphalt treated base (ATB) . We recommend that heavily loaded areas be provided with three (3) inches of AC over six (6) inches of CRB or four (4 ) inches of ATB. The heavily loaded areas are typically main driveways and dumpster areas . Where the subbase is composed of silty, water- sensitive soils , and there is irrigated landscaping adjacent to and at an elevation higher than the pavement , we suggest that perimeter drains be installed to intercept the water that would otherwise saturate the pavement subbase . The pavement section recommendations and guidelines are based on our experience in the area and on what has been successful in similar situations . We can provide recommendations based on expected traffic loads and R value tests , if requested . Some maintenance and repair of limited areas can be expected . To provide for a design without the need for any repair would be uneconomical . We stress again , however , that the performance of site pavements is related to the strength and stability of the underlying subgrade . GENERAL EARTHWORK AND STRUCTURAL FILL We recommend that the building and pavement areas be stripped and cleared of all surface vegetation , all organic matter , and other deleterious material . The stripped or removed materials should not be mixed with any materials to be used as structural fill . Should the foundations and/or slabs for the existing structure also be removed , and structural fill should be placed in the crawl space areas where buildings are located . Structural fill is defined as any fill placed under the building , behind permanent retaining or foundation walls , or in other areas where the underlying soils need to support GEOTECH CONSULTANTS , INC . Seattle-Renton Investors JN 91148 • May 16 , 1991 Page 10 loads . Geotech Consultants , Inc . should observe site conditions during and after excavation prior to placement of any structural fill . All structural fill should be placed in horizontal lifts with a moisture content at or near the optimum moisture content . The optimum moisture content is that moisture content which results in the greatest compacted dry density . The moisture content of fill soils is very important and must be closely controlled during the filling and compaction process . The allowable thickness of the fill lift will depend on the material type , compaction equipment used , and the number of passes made to compact the lift . In no case should the lifts exceed twelve ( 12) inches in loose thickness . The following table presents recommended relative compaction for structural fill : Minimum Relative Location of Fill Placement Compaction Beneath footings , slabs or 95% . walkways Behind retaining walls 90% Beneath pavements 95% for upper 12 inches of subgrade , 90% below that level Where : Minimum Relative Compaction is the ratio , expressed in percentages , of the compacted dry density to the maximum dry density , as determined in_ accordance with ASTM Test Designation D-1557-78 (Modified Proctor) . Use of On-Site Soils If grading activities take place during wet weather , or when the silty , on-site soils are wet , site preparation costs may be higher because of delays due to rains and the potential need to import granular fill . The on-site soils are generally silty and thus are moisture sensitive . Grading operations will be very difficult when the moisture content of these soils exceeds the optimum moisture content by more than two percent . • GEOTECH CONSULTANTS , INC . Seattle-Renton Investors JN 91148 May 16 , 1991 Page 11 The moisture content of the silty , on-site soils must be at or near the optimum as they cannot be consistently compacted to the required density when the moisture content is greater than optimum . The moisture content of the on-site soils at the time of our explorations was generally above the estimated optimum moisture content . The on-site sand or gravel soils underlying the topsoil could be used as structural fill if grading operations are conducted during dry weather and when drying of the wet soils by aeration is possible . During excessively dry weather it may be necessary to add water to achieve optimum moisture content . Moisture sensitive soils may also be susceptible to excessive softening and "pumping" from construction equipment traffic when the moisture content is greater than the optimum moisture content . Ideally , structural fill which is to be placed in wet weather should consist of a select pit-run gravel or granular material having no more than five (5 ) percent silt or clay particles . The percentage of particles passing the No . 200 sieve should be measured from that portion of the soil passing the three- quarter-inch sieve . LIMITATIONS The analyses , conclusions and recommendations contained in this report are based on site conditions as they existed at the time of our exploration and assume that the soils encountered in the test pits are representative of the subsurface conditions of the site . If the subsurface conditions encountered during construction are significantly different from those observed in the explorations , we should be advised at once so that we can review these conditions and reconsider our recommendations where necessary . Unanticipated soil conditions are commonly encountered on construction sites and cannot be fully anticipated by merely taking soil samples in test pits . Subsurface conditions can also vary between exploration locations . Such unexpected conditions frequently require that additional expenditures be made to attain a properly constructed project . It is recommended that the owner consider providing a contingency fund to accommodate such potential extra costs and risks . • GEOTECH CONSULTANTS , INC . Seattle-Renton Investors JN 91148 40 May 16 , 1991 Page 12 This report has been prepared for the exclusive use of Seattle-Renton Investors and their representatives for specific application to this project and site . our recommendations and conclusions are based on the site materials observed , and selective laboratory testing and engineering analyses . The conclusions and recommendations are professional opinions derived in accordance with current standards of practice within the scope of our services and within budget and time constraints . No warranty is expressed or implied . The scope of our services does not include services related to construction safety precautions and our recommendations are not intended to direct the contractor ' s methods , techniques , sequences or procedures , except as specifically described in our report for consideration in design . The scope of our work did not include an environmental audit , however , we can provide this service, if requested . We recommend that this report , in its entirety, be included in the project contract documents for the information of the contractor . ADDITIONAL SERVICES . It is recommended that Geotech Consultants , Inc . provide a general review of the geotechnical aspects of the final design and specifications to verify that the earthwork and foundation recommendations have been properly interpreted and implemented in the design and project specifications . It is also recommended that Geotech Consultants , Inc . be retained to provide geotechnical consultation , testing , and observation services during construction . This is to confirm that subsurface conditions are consistent with those indicated by our exploration , to evaluate whether earthwork and foundation construction activities comply with the intent of contract plans and specifications , and to provide recommendations for design changes in the event subsurface conditions differ from those anticipated prior to the start of construction . However , our work will not include supervision or direction of the actual work of the contractor , his employees or agents . Also , job and site safety, and dimensional measurements , will be the responsibility of the contractor . • GEOTECH CONSULTANTS , INC. Seattle-Renton Investors JN 91148 May 16 , 1991 Page 13 The following plates are attached and complete this report : Plate 1 Vicinity Map Plate 2 Soils Exploration Plan Plates 3 - 6 Test Pit Logs Plate 7 - 8 Grain Size Analysis Plate 9 Footing Drain Detail Respectfully submitted , 0,40 R. F/�y tips GEOTECH CONSULTANTS , INC . v�`� /F� • • �P of w `.ti '� e D. Robert Ward t " Geotechnical Engineer �s .• �� +•`.•- James R . Finley , Jr . P . E . Principal Attachments DRW/JRF : cka GEOTECH CONSULTANTS , INC . SF °=F 4� 34 35 6 QO Fr a COUGAR MOUNTAIN 6 `•' REGIONAL WILOLAND • iK. n SE 91 ST SE 91STST `1 PARK .. .. " y a 1 4A y VAC IF y RD 1 95TH PL N F ........... 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ST > nH E 121ST ST o < ST E_120TH Sw yp- °s �6 WE 6TH CT I 1 N 5T W i rr?\' NEE N F.IL > > PL e w <Z a a I ---COALFIELD QI 6TH T 1 _ PARK.- _ I 124TH T 9wmm Z I SE- 1 H T I > > NTOU ST I I1 H AV HE u W 4TH $T S a SE 12ETH ST SE 123TH1 .7 ST W W I/4 1 I 1/ fS` 64 / 6 1 y/w H _ W1 $E1129TH ST NI 1 N N > NtN �W < R P > > NI I Li I 1 SE !> a >I _ QI a 1 I > 130T H <I < W 1 ~ tS�_ Ai AT I $T_ <I I i " SE 131STN 131ST < DOWNSHEATHE SSE <I 132N41 I ST I -5E 132ND ST a SE �•f -- -----�--- 132 ST PARK(SI7E) } �i IJ I SE 1 N P = x132N U kE 13T PL H ) i ` a •o FI 13ETH ST Q �I i > SE Q 134TH ST x SE sE 134TH < : SE.T.ST z 135TH p ^i I I <. Q SE 13 T I $ T F P I 36rH (JS� SE 136TN ST.JISE TE 1 .. w N... Q --- fS SE 13ETH;> R w,. x G SE 131TH PL 137TH 1A PL nncnTv VICINITY MAP . GEOTECH 4802 -4816 N.E. SUNSET BLVD. CONSULTANTS, INC. RENTON, WASHINGTON Job No. Date_ Plate_ 91148 MA Y 1991 1 —— J TP-7 C o , (� F.F.-423.0 ti v r LL I 1 0 TP-2 / I � I -A ®TP-1 O F.F.-412.0 N WITH CRAWL Z 1 SPACE N F.F.-422.0 F.F.-418.0 \ a / F.F.-412.0 \ \ Z TP-6 WITH CRAWL _ �TP-4 SPACE O J Til J I / a O a F.F.-412.0 w cr X / U W U W / TP-3 3 Co Co 0 TIP-5 LEGEND: SITE EXPLORATION PLAN . A TP-1 APPROXIMATE TEST PIT LOCATIONS GEOTECH 4802-4816 N.E. SUNSET BLVD. O BUILDING NUMBER CONSULTANTS RENTON, WASHINGTON NO. scale.. P/oleo 91148 MAY 1991 2 \l J`� ``i0 TEST PIT 1 r � �� �eQ �o�Goat • 0 USCS Description Reddish-brown to tan, silty SAND with gravel, trace of organics, fine grained, moist, loose to medium-dense (weathered glacial till). 13.0 : becomes grayish :SM 5 becomes gray, dense (glacial till) 10 Test pit completed at 9 feet below existing grade on 5-3-91. No groundwater encountered during excavation. No caving. 15 TEST PIT 2 • eQ o�ti 0 e�`e G USCS Description Reddish-brown to tan, silty SAND with gravel, trace of organics, moist, loose to medium-dense (weathered glacial till). SM becomes gray, very dense (glacial till). 5 11.9 Test pit completed at 7 feet below existing grade on 5-3-91. No groundwater encountered during excavation. 10 No caving. 15 TEST PIT LOGS GEOTECH 4802 -4816 N.E. SUNSET BLVD. iCONSULTANTS, INC. RENTON, WASHINGTON ff : Date: Loggedby: Plate: 148 MAY 1991 DRW 3 TEST PIT 3 Qo �`o God USCS Description 0 Topsoil Reddish-brown, gravelly, silty SAND with many organics, very moist, loose (weathered glacial till) SM lens of wet silt 5 becomes gray, very silty, dense (glacial till). becomes less silty,moist, very dense. Test pit completed at 8 feet below existing grade on 5-3-91. 10 No groundwater encountered during excavation. No caving. 15 TEST PIT 4 eQ o`o ore 0 Go USCS Description Topsoil SM • • ; Reddish-brown, silty SAND with gravel and organics, very moist, loose • G 3.8 Brown to gray, sandy GRAVEL, wet to saturated, loose to medium-dense. 5 Gray, very silty SAND with gravel, very moist, medium-dense to dense AM (glacial till). 10 Test pit completed at 9 feet below existing grade on 5-3-91. Groundwater encountered at 4 feet during excavation. No caving. 15 TEST PIT LOGS GEOTECH 4802 -4816 N.E. SUNSET BLVD. CONSULTANTS, INC_ RENTON, WASHINGTON Job No: Date: Logged by: Plate: 91148 MA Y 1991 DRW 4 TEST PIT 5 0 G� USCS Description Reddish-brown, gravelly, silty SAND, some organics, very moist, loose to medium-dense (weathered glacial till). becomes gray, very silty, medium-dense to dense (glacial till). SM 5 becomes less silty, moist, dense. Test pit completed at 8 feet below existing grade on 5-3-91. 10 No groundwater encountered during excavation. No caving. 15 TEST PIT 6 Q 6 �e \` Goo USCS Description 0 Reddish-brown, slightly silty, sandy GRAVEL, few organics, 6.8 few cobbles, moist, loose to medium-dense. SP Brown to gray, very gravelly SAND, cobbles, very coarse grained, GP moist, medium-dense. 5 ... Gray, gravelly, silty SAND, very moist, dense to very dense (glacial till). SM 10 Test pit completed at 9 feet below existing grade on 5-3-91. No groundwater encountered during excavation. Slight caving between 2 and 6 feet. 15 TEST PIT LOGS �. _. GEOTECH 4802 -4816 N.E. SUNSET BLVD. CONSULTANTS, INC. RENTON, WASHINGTON ff _ Date: Loggedby: Plate: i48 _ MAY i99i DRW 5 `l J`e L`�l TEST PIT 7 Qr \yt `e� USCS Description 0 Reddish-brown, silty SAND with gravel, organics, moist, loose to medium-dense (weathered glacial till). becomes tan, more gravelly, cobbles. SM becomes gray, very dense (glacial till). 5 Test pit completed at 7 feet below existing grade on 5-3-91. 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CNN■�� �. =�r�--�0 NN�N�N■ �NI MMINN■NNNN�■� ■�/�N ■NNNN .• NN�NNN■NNNNNN• .■ ► N■N . ■NN�� �N�N.NNNNNN •• �N=NN■NNNNNN ■� L ■ N■BNB �� NN■NN■NNNN ■� rilillAk--�I�1 i�\ N■NNI� � • �N���■■■NI.1..1.NNE.■�i.1■NN.�■�INN.IN■�s:.�:i►!��N��NN■�N�� .• C C® jpmm ■ • ®®®®� - N■�����■NN■���NN.■NIN�NN■N.�.���N■��■�NHI � N.H���■�\■�NH� ■NI�HI N.�.�■���N.�N■NNE • N■HNH�■��i1��N��/NINE �■�.�■��HN■��.���N■ • �Hm■�� N��►� Nam. ■�����wmmm�� z -MIN co Z gm m . , • Mumm • Slope back/ill owoy from foundation. TIGHTL/NE ROOF DRAIN Do no/ connect to fooling drain. BACKFIL L See text for VAPOR BARRIER requirements. SLAB WASHED ROCK 4"min. 0 6 min. FREE-DRAINING NONWOVEN GEOTEXT/LE SAND/GRAVEL FILTER FABRIC 4"PERFORATED HARD PVC PIPE Invert of least as low as tooling and/or crawl space. Slope to drain. Place weepholes downward. ' FOOTING DRAIN DETAIL GEOTECH 4802 - 4816 N.E. SUNSET BLVD. CONSULTANTS RENTON, WASHINGTON - �— F77 No.+ Ooze Sco/e P/o/t 91148 MAY 1991 N.T.S. 9 VII. BASIN AND COMMITTEE PLAN AREAS The project does not lie within any adopted Committee plan or basin area. • Page 7 of 11 5025.001 [AS/sdc] _.r •rarr:t- n o� Al r _ tr A - m > FIN- ij" � tV c (r� .i ,�� `.�: -� '',mac t •� It i It / ', r.._� Ia t i t Ii � 1 rt tr r r' Fit G rr 1 I t t . ,q�✓ �.� c ac r tt '� � rf rrif rl tL r� _r Ef rf ' ,I i rl r' �� •� fir= „� �� ► r ,,--�,�r „�'' .r /t � � i AI ft At- tit(//• _rrf-� I N� �, '�:, - _,.� I tr r"Ai, r I •I�• D ip,c Z m \ Z V ^ a n � m D ' IAcw4w .. N.wl a.n•.11..1 J � _ \\ C•e. T Ue•+ � l/ aa�y SKYKOMISH Li��- i p �n� '• Na.�.s UM. RIVER �a SN QU MIE a Heave f• ,. 'I - TWW U— Snoquaknle FU a -- ' � mi.C,., BASIN - ' " RIVER 1 PUGEI' ! f x n � --; - 'ysno�HlRl. seer - . BASIN 1 - - - W _ r, t rr — � Rivet Sou1W ) ` 1 - Z. / ,� i 1 ^' � LIB '�.— ! / r -. •. JtAt4 � — Maaeeer� \ \ •LL L.Y- � t _...-. � _ = _ _^, .. i _ �s tr- nt Des Ho[es _ Figure E 7 i` ti res mac- 1 , UPW +: 1 DRAINAGE BASINS I -- i•'J "'J ` ` t . S.C'w'+4�w1 I ` i d..e`t 10.E - ` ! v, e i, ,•T+ i �' — _ *, ti.:,.. - King county i ,. . M, ; OC DRAlNAG a ; ; - �TTOFSEAIILEWATERSHED �VJ ,. i } y�_.! u _ s: Ewa` _ ::� �^ti,. e -��• �1.� - - ._.,. Major Basin Boundary Upper = ;1, ? J, • � Sub-Basin Boundary "Cak Creek C — - Source: King County Sensitive Areas Map Folio,Wetlands Supplement ('jTY OF tA(AMA WATERSHED .. .. - • 1. y �' _ `DIVER. O 1 2 1 4 5 1, 1 8 Miles • VIII. OTHER PERMITS A. Sewer Extension Permit B. Water Permit C. Building Permit • Page 8 of 11 5025.001 [AS/sdcl IX. TEMPORARY EROSION/SEDIMENTATION CONTROL DESIGN Temporary erosion/sedimentation control measures have been designed for this project in accordance with the King County and City of Renton standards. The erosion/sedimentation control measures consist of a sediment trap basin along with mirafi filter fence, intercepting ditch and rock check dams to control the sediment laden water from discharging to the downstream drainage system. Please refer to the temporary erosion control plan for more details. • Page 9 of 11 5025.001 [AS/sdcl 17-all FI�6 50�3 7 m PO eo✓j 5ed ,',nP,T 7 uP 5;Z Ca �Cr.laf�'o-.5, • lJas,11 Peery Ta be &6f,, rbect- 2- $ ► c- W W W W W W YY XXX V)IA N coo r Computing the sediment storage volume - The sediment storage volume required is the volume a a a required to contain the annual sediment yield to the trap and can be estimated by using the r r r Universal Soil Loss Equation (USLE) developed by the United States Department of Agriculture. N N CI �o ASED = R*K*LS*CV*PR Where AsEo - annual sediment yield in tons per acre R = rainfall erosion index; use R'=2.22(P2)2.2; where P2 is the 2 year/24 hour precipitation in inches (See 2 year - 24 hour Isopluvial Map in Figure 3.5.1 C) K = soil erodibility factor, from Table 5.4.4A or as determined by field and laboratory testing by a geologist, soil scientist, or geotechnical engineer. LS = length-slope factor; from Table 5.4.4E (note, lengths measured are horizontal distance from a plan view) CV = cover factor, use 1.0 which represents no ground cover during the construction process. PR = erosion control practice factor; use 1.3 which represents compacted and smooth slopes. Note, the USLE rainfall erosion index equation for the SCS Type 1A storm region is R=10.2 (P2)2.2, where P2 is the total precipitation for the 2 year, 6 hour duration design storm. Since the totai precipitation for the 2 year, 6 hour duration design storm is equal to exactly one-half of the total precipitation for the 2 year, 24 hour duration design storm, the equation can be rearranged as shown. w - 2.2 i6Fd - 2. 22 ( 2 ) 0.15 ) l0.32 5 L6&d= A5e-d Cc, Ac ) ( 0- 6S )( �.$ ) _ 1_ $2 Toes 1�se1/0 _ 1. 82/0, 3 SPA -r"),1. 5.LI..LA R Use Fit 5.u.yc- Vsec'g 162 cF • Wb= o use 1 \,,JLz Cl use lo' L1T= 21 v5c- 22, � 6 = Igo 1.. � : 2-► ' �-T= 3y ' W W W la W W / xxx y.g moo �r �Cry / avv y,s CC CVM M CC CV 71 0 '-'------ - a y.s� I Bot/O— im fo'on w 3 ,5/ J,f?fh) -rop KING COUNTY, WASHINGTON, SURFACE WATER DESIGN M-ANUAL FIGURE 5.4.4C SEDIMENT TRAP SIZE AND DIMENSIONS Column Descriptions Assumptions Vsed=Sediment storage volume between the interface and bottom areas L/W at interface(unitless)= 3 Vtotal=Volume of sediment trap between the top and bottom areas Side slopes along length,H/L(unitless)= 0.33 Ab,At=area of the bottom(b)and top(t)of the trap Side slopes along width,H/W(unitless)= 0.33 Ai=area of the interface(i)between the settling zone and sediment storage Depth from interface to bottom(ft)= 1.5 Lb,Li,Lt=Average length from inlet to outlet at the bottom,interface,and top elevations Depth from top to interface(ft)= 2 Wb,Wi,Wt=Width of the bottom,interface,and top areas Total Depth(ft)= 3.5 0 0 Volumes ft^3 Areas ft!2 " " ( { ) Width and 7.engftl5(ft) Volumes(ft 3 Areas(ft 2) Widttl:and'Lengths(ft) Vsed: Vtotal ;:Ab Ai At VVb tb VYl U Wt tt` Vsed wtai Ab Al At.,< Lb ::VVi VVf Lt: 162 1,176E 0 243 819E 0 18 9 27 21 39 5,832 16,926E 3,240 4,563 6,519E 30 108 39 117 51 129 221 1,397 21 300 924E 1 21 10 30 22 42 6.161 17,777: 3.441 4.800 6,864 31 111 40 120 52 132 288 1,638E 48 363 1,035E 2 24 11 33 23 45 6,498 18,648E 3.648 5.043 7,1551 32 114 41 123 53 135 365 1,901E 81 432 1,152E 3 27 12 36 24 48 6.845 19,541E 3.861 5.292 7,452E 33 117 42 126 54 138 450 2,184E 120 507 1,275E 4 30 13 39 25 51 7.200 20,454:: 4.080 5.547 7,755E 34 120 43 129 55 141 545 2.4891 165 588 1,404E 5 33 14 42 26 54 7,565 21.3a9i 4.305 5,8W 8,064 35 123 44 132 56 144 648 2,814E 216 675 1,539E 6 36 15 45 27 57 7,938 22,344: 4.536 6,075 8,379: 36 126 45 135 57 147 761 3,161E 273 768 1,680E 7 39 16 48 28 60 8,321 23,321E 4,773 6.348 8,700E 31 129 46 138 58 150 982 3,528E 336 867 1,827E 8 42 17 51 29 63 8.712 24,318E 5.016 6.627 9,027E 38 f32 47 141 59 153 1.013 3,917: 405 972 1,980E 9 45 18 54 30 66 9,113 25,337: 5.265 6.912 9,360E 39 135 48 144 60 156 1.152 4,326E 480 1,083 2,139: 10 48 19 57 31 69 9,522 26,376E 5.520 7,203 9,699E 40 138 49 147 61 159 1.301 4,757E 561 1,200 2,304E 11 51 20 60 32 72 10.368 28,518E . 6,048 7,803 10,395E 42 144 51 153 63 165 1,458 5,208E 648 1.323 2,475E 12 54 21 63 33 75 11.250 30,744E 6,600 8.427 11,115E 44 150 53 159 65 171 1,625 5,6811 741 1,452 2,6521 13 57 22 66 34 78 12.168 33,054: 7.176 9,075 11,859: 46 156 55 165 67 177 1.800 6,174E 840 1,587 2,835E 14 60 23 69 35 81 13,122 35,448E 7,776 9.747 12,627E 48 162 57 171 69 183 1,985 6,689E 945 1.728 3,024E 15 63 24 72 36 84 14,112 37,926E 8.400 10.443 13,419E 50 168 59 177 71 189 2,178 7,224E 1.056 1,875 3,219E 16 66 25 75 37 87 15.138 40,488E 9.048 11,163 14,235E 52 174 61 183 73 195 2.381 7,781E 1,173 2.028 3,4201 17 69 26 78 38 90 16,200 43,134E 9,720 11,907 15,075E 54 180 63 189 75 201 2,592 8,358: 1.296 2.187 3,627E 18 72 27 81 39 93 17,298 45,864: 10,416 12.675 15.939: 56 186 65 195 77 207 2,813 8.957: 1.425 2,352 3,840 19 75 28 84 40 96 18,432 48,678: 11.136 13,467 16,827E 58 192 67 201 79 213 3.042 9,576E 1,560 2.523 4,059E 20 78 29 87 41 99 19,602 51,576E 11,880 14.283 17,739E 60 198 69 207 81 219 3,281 10,217: 1,701 Z700 4,284E 21 81 30 90 42 102 20,8W 54,558 12.648 15.123 18,675E 62 204 71 213 83 225 3.528 10,878E 1,848 7-883 4,515E 22 84 31 93 43 105 22,050 57,624: 13,440 15.987 19,635E 64 210 73 219 85 231 3,785 11,561E 2,001 3,072 4,752E 23 87 32 96 44 108 23,328 60,774E 14.256 16,875 20,619E 66 216 75 225 87 237 4,050 12,264E 2.160 3,267 4,995E 24 90 33 99 45 111 24.642 64,008E 15,096 17,787 21,627E 68 222 77 231 89 243 4,325 12 989E 2,325 3,468 5,244E 25 93 34 102 46 114 25.992 67,326E 15,960 18,723 22,659E 70 228 79 237 91 249 4,608 13,734E 2,496 3.675 5,499E 26 96 35 105 47 117 27.378 70,728E 16,848 19,683 23,715E 72 234 81 243 93 255 4,901 14,501E 2.673 3,888 5,760E 27 99 36 108 48 120 28,800 74,214E 17,760 20,667 21,795E 74 240 83 249 95 261 5,202 15,288E 2,856 4,107 6,027E 28 102 37 111 49 123 30,253 77,784E 18,696 21,675 25,899E 76 246 85 255 97 267 5.513 16,097E 3.045 4.332 6,300E 29 105 38 114 50 126 31.752 81,438E 19,656 22,707 27,027E 78 252 87 261 99 273 5.832 16,926E 3,240 4,563 6,579E 30 108 39 117 51 129 1 33.282 85,176E 20,640 23,763 28,179E 80 258 89 267 101 279 5.4.4.2 SEDIMENT POND Purpose To collect and store sediment from sites cleared and/or graded during construction prior to establishment of permanent vegetation and/or construction of permanent drainage facilities. It is usually a temporary measure with a design life less than 1 year; however, it may be a more permanent facility, especially if required to provide runoff quality control until the site area is permanently stabilized. Conditions Where Practice Applies Where the tributary drainage area is 10 acres or less. • �, 5.4.4.2-1 11/9 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL • o To complete the design of the temporary sediment trap: a. The "Pond Geometry Equations" section in the "Reference" portion at the back of the Manual may also be useful in designing the sediment trap. b. A 3:1 aspect ratio between the trap length and widtf'i of the trap is desirable. Length is defined as the average distance from the inlet to the outlet of the trap. This ratio is included in the computations for Figure 5AAC for the surface area at the interface between the settling zone and sediment storage volume. C. Determine the bottom and top surface area of-the sediment storage volume to be provided (see Figure SAAC) while not exceeding 1.5' in depth and 3:1 side slope from the bottom of the trap. Note the trap bottom should be level. d. Determine the total trap dimensions by adding an additional 2' of depth above the surface of the sediment storage volume, while not exceeding 3:1 side slopes, for the required settling volume. (see Figure 5.4.4C) TABLE 5AAA HYDROLOGIC SOIL GROUP OF THE SOILS IN KING COUNTY SOIL SOIL EROD- EROD- HYDROLOGIC IBILITY HYDROLOGIC IBILITY SOIL GROUP GROUP* FACTOR,'K' SOIL GROUP GROUP* FACTOR,'K' Alderwood C 0.15 Orcas Peat D 0.00 Arents, Alderwood C 0.15 Oridia D 0.49 Arents, Everett B 0.17 Ovall C 0.17 • Beausite C 0.15 Pilchuck C 0.10 Bellingham D 0.32 Puget D 0.28 Briscot D 0.32 Puyallup B 0.28 Buckley D 0.32 Ragnar B 0.32 Coastal Beaches Variable 0.05 Renton D 0.43 Earimont Silt Loam D 0.37 Riverwash Variable - Edgewick C 0.32 Salal C 0.37 Everett A 0.17 Sammamish D 0.37 Indianola A 0.15 Seattle D 0.00 Kitsap C 0.32 Shacar D 0.00 Klaus C 0.17 SI Silt C 0.37 Mixed Alluvial Land Variable 0.10 Snohomish D 0.32 Neilton A 0.10 Sultan C 0.37 Newberg B 0.32 Tukwila D 0.00 Nooksack C 0.37 Urban Variable - Norm. Sandy Loam D 0.24 Woodinville D 0.37 HYDROLOGIC SOIL GROUP CLASSIFICATIONS A. (Low runoff potential). Soils having high Infiltration rates, even when thoroughly wetted, and consisting chiefly of deep,well-to-excessively drained sands or gravels. These soils have a high rate of water transmission. B. (Moderately low runoff potential). Soils having moderate infiltration rates when thoroughly wetted, and consisting chiefly of moderately fine to moderately coarse textures. These soils have a moderate rate of water transmission. C. (Moderately high runoff potential). Soils having slow Infiltration rates when thoroughly wetted,and consisting chiefly of soils with a layer that Impedes downward movement of water, or soils with moderately fine to fine textures. These soils have a slow rate of water transmission. D. (High runoff potential). Soils having very slow Infiltration rates when thoroughly wetted and consisting • chiefly of clay soils with a high swelling potential, soils with a permanent high water table, soils with a hardpan or clay layer at or near the surface, and shallow soils over nearly Impervious material. These soils have a very slow rate of water transmission. From SCS,TR-55, Second Edition, June 1986, Exhibit A-1. Revisions made from SCS, Soils Interpretation Record, Form ##5, September 1988. 5.4.4.1-3 1/90 a x � z IS vnlues for following slope lengths 1,ft(m) LS vuh,es for following slope lengths 1,ft(no Slope Slope gradient 10 20 .10 -10 50 GO 70 80 90 IN 150--200 250 300 350 400 450 500 600 700 800 900 1000 a C7 ratio X. ", (3.0) (6.1) (9.1) (12.2) (15.2) (18.3) (21.3) (2.1.4) (27.4) (30.5) (46) (fit) (76) (91) (107) (122) (137) (15.2) (16) (213) (244) (274) (305) r 0.5 0.06 0.07 0.07 0.08 0.08 0.09 0.09 0.09 0.09 0.10 0.10 0.1,1 0.I 1 0.12 0.12 0.13 0.13 0.I. 0.14 0.1.1 0.14 0.15 0.15 C 100:1 1 0.08 0.09 0.10 0.10 0.11 0.11• 0,12 0.12 0.12 0.12 0.I.1 0.I.1 0.150.I fi 0.16 0.I fi 0.17 0.17 0.18 0.18 0.19 0.19 0.20 z 2 0.10 0.12 0.14 0.1:; O.If, 0.17 0.18 0.19 0.19 0.20 0.23 0.25 0.26 0.28 0.29 0.10 0.32 0.33 0.34 0.36 0.37 0.39 0.40 r .3 3 0.11 0.18 0.20 0.22 0.23 0.25 0.26 0.27 0.28 0.29 0.32 0.15 0.38 0.40 0.42 0.43 OAS 0.46 0-493 0.51 0.54 0.55 0.57 C � -- •1 0.1(, 0.21 0.25 0.28 0.30 0.33 0.15 0.17 0.38 OAO 0.47 0.53 0,58 0.62 0.66 0.70 0.71 0.7G 0.82 0.87 0.92 0.96 1.00 20:1 5 0.17 0.24 0.29 0.:34 0.38 0.41 0.45 0A8 0.51 0.53 0.66 0.76 0.85 0.93 1.00 1.07 1.13 1.20 1.31 1.42 1.51 1.60 1.69 G G 0.21 0.30 0.37 0.43 0.48 0.52 0.56 0.60 0.6.1 0.67 0.82 0.95 1.06 1.16 1.26 1.34 L43 1.50 1.65 1.78 1.90 2.02 2.13 7 0.26 0.37 0.45 0.52 0.58 0.6.1 0.69 _ 0.74 0.78 0.82 1.01 1.17 1.30 1.43 1.54 I.G5 1.75 1.8.1 2.02 2.18 2.33 2.47 2.61 � 1 8 0.31 0.44 0.54 0.63 0.70 0.77 0.81 0.89 0.9.1 0.99 1'.21 1.40 1.57 1.72 1.85 198 2.10 2.22 2.43 2.62 2.80 2.97 3.13 x 0 0.17 0.52 0.6.1 0.74 0.81 0.91 0.98 1.05 1.11 1.17 1.44 1.66 1.85 2.03 2.19 2.35 2.49 2.62 2.87 3.10 3.32 3.52 3.71 10:1 10 0.43 0.61 0.75 0.87 0.97 1.06 1.15 1.22 1.30 1.37 1.68 1.94 2.1 G 2.37 2.56 2.74 2.90 3.06 3.35 3.62 3.87 4.11 4.33 11 0.50 0.71 0.86 1.00 1.12 1.22 1.32 1.41 1.50 1.58 1.93 2.23 2.50 2.74 2.95 3.16 3.35 3.53 3.87 4.18 4.47 4.74 4.99 8:1 12.5 0.61 0.86 1.05 1.22 1.36 1.49 1.61 1.72 1.82 1.92 2.35 2.72 3.04 3.33 3.59 3.84 4.08 4.30 4.71 5.08 5.43 5.76 6.08 15 0.81 1.14 1.40 1.62 1.81 198 2.14 2.29 2.43 2.56 3.13 3.62 4.05 4.43 4.79 5.12 5.43 5,72 6.27 6.77 7.24 7.68 8.09 6:1 16.7 0.96 1.36 1.67 1.92 2.15 2.36 2.54 2.72 2.88 3.04 3.72 4.30 4.81 5.27 5.69 6.08 6.45 6.80 7.45 8.04 8.60 9.12 9.62 z 5:1 20 1.29 1.82 2.23 2.58 2.88 3.16 3.41 3.65 3.87 4.08 5.00 5.77 6.45 7.06 7.63 8.16 8.65 9.12 9.99 10.79 11.54 12.24 12.90 (n j� 4h:1 22 1.51 2.13 2.61 3.02 3.37 3.69 3.99 4.27 4.53 4.77 5.84 6.75 7.54 8.26 8.92 9.54 10.12 10.67 11.68 12.62 13.49 14.31 15.08 4:1 25 1.86 2.63 3.23 3.73 4.16 4.56 4.93 5.27 5.59 5.89 7.21 8.33. 9.31 10.20 11.02 11.78 12.49 13.17 14.43 15.58 16.66 17.67 18.63 -' 30 2.51 3.56 4.36 5.03 5.62 6.16 6.65 7.11 7.54 7.95 9.74 11.25 12.57 13.77 14.88 15.91 16.87 17.78 19.48 21.04 22.49 23.86 25.15 A 3:1 33.3 2.98 4.22 5.17 5.96 6.67 7.30 7.89 8.43 8.95 9.43 11.55 13.34 14.91 16.33 17.64 18.86 20.00 21.09 23.10 24.95 26.67 28.29 29.82 35 3.23 4.57 5.GO 6.46 7.23 7.92 8.55 9.14 9.70 10.22 12.52 1.1.46 16.16 17.70 19.12 20.44 21.68 22.86 25.04 27.04 28.91 30.67 32.32 n 29:1 40 4.00 5.66 6.93 8.00 8.95 9.80 10.59 11.32 . 12.00 12.65 15.50 17.89 20.01 21.91 23.67 25.30.26.84 28.29 30.99 33.48 35.79 37.96 40.01 (TJ 45 4.81 6.80 8.33 9.61 10.75 11.77 12.72 13.60 14.42 15.20 18.62 21.50 24.03 26.33 28.44 30.40 32.24 33.99 37.23 40.22 42.99 45.60 48.07 tt 2:1 50 5.64 7.97 9.76 11.27 12.60 13.81 14.91 15.9.1 16.91 17.82 21.83 25.21 28.18 30.87 33.34 35.65 37.81 39.85 43.66 47.16 50.41 53.47 56.36 G 55 6.48 9.16 11.22 12.96 14.48 15.87 17.14 18.32 19.43 20.48 .25.09 28.97 32.39 35.48 38.32 40.97 43.45 45.80 50.18 64.20 57.94 61.45 64.78 IY.:1 57 6.82 9.64 11.80 13.63 15.24 1.6.69 18.03 19.28 20.45 21.55 26.40 30.48 34.08 37.33 40.32 4110 45.72 48.19 52.79 57.02 60.9G 64.66 68.15 � GO 7.32 10.15 12.68 14.64 16.37 17.93 19.37 20.71 21.96 23.15 28.35 12.74 36.60 40.10 43.31 46.30 49.11 51.77 5G.71 61.25 65.48 69.45 73.21 m I'f,:I G6.7 8.44 11.93 14.61 16.88 18.87 20.67 22.32 23.87 25.31 26.68 32.68 37.74 42.19 46.22 49.92 53.37 5G.GO 59.6G 65.36 70.60 75.47 80.05 84.18 70 8.98 12.70 15.55 17.96 20.08 21.99 2:1.75 25.39 26.93 28.39 34.77 40.15 44.89 49.17 53.11 56.78 60.23 63.48 69.54 75.12 80.30 85.17 89.78 75 9.78 13.83 16.94 19.56 21.87 23.95 25.87 27.66 29.34 30.92 37.87 43.73 48.89 53.56 57.85 61.85 65.GO 69.15 75.75 81.82 87.46 92.77 97.79 Crl I Y..:I 80 10.55 14.93 18.28 21.11 23.60 25.85 27.93 29.85 31.66 33.38 40.88 47.20 52.77 57.81 62.44 66.75 70.80 74.63 81.76 88.31 94.41 100.13 105.55 to 85 11.30 15.98 19.58 22.61 25.27 27.69 29.90 31.97 33.91 35.74 43.78 50.55 56.51 61.91 66.87 71.48 75.82 79.92 87.55 94.57 101.09 107.23 113.03 90 12.02 17.00 20.82 24.04 26.88 29.4.1 31.80 :14.00 36.06 38.01 46.55 53.76 GO.10 65.84 71.11 76.02 80.63 84.99 93.11 100.57 107.51 114.03 120.20 C) 95 12.71 17.97 22.01 25.41 28.41 .11.12 3:1.62 35.94 38.12 40.18 49.21 56.82 63.53 69.59 75.17 80.36 85.23 89.84 98.42 106.30 113.64 120.54 127.06 z 1:1 100 13.36 18.89 2..14 26.72 29.87 32.72 35.34 37.78 40.08 42.24 51.74 59.74 66.79 73.17 79.03 84.49 89.61 94.46 103.48 111.77 119.48 126.73 133.59 'Calculated from 65.41 X s? 4.56 X s 1 10.(X10 t s t ]0,(X10+0.0(SJ(72.5l/T 1-9topographic factor z l-slope length,ft(m X 0.3048) s -slope steepness, m - exponent dependent upon slope steepness (0.2 for slopes< I',,.0.3 for slopes I to 3%, 0.4 for slopes IS to 4.5%,and r 0.5 for slopes>5%) X. ADDITIONAL DOCUMENTS • • • Page 10 of 11 - 5025.001 [AS/sac] XI. MAINTENANCE AND OPERATION MANUAL • • • Page 11 of 11 5025.001 [AS/sac] KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL MAINTENANCE REQUIREMENTS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 1 - PONDS Maintenance Conditions When Maintenance Results Expected Component Defect is Needed When Maintenance Is Performed General Trash & Debris Any trash and debris which exceed 1 Trash and debris cleared from site. cubic foot per 1000 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 Any poisonous vegetation which may No danger of poisonous vegetation where Vegetation constitute a hazard to County personnel County personnel or the public might or the public. Examples of poisonous normally be. (Coordination with vegetation include: tansy ragwort, poison Seattle/King County Health Department) oak,stinging nettles,devils club. Pollution Oil,gasoline,or other contaminants of No contaminants present other than a one gallon or more or any amount found surface film. (Coordination with that could: 1)cause damage to plant, Seattle/King County Health Department) animal,or marine life; 2)constitute a fire hazard;or 3)be flushed downstream during rain storms. Unmowed Grass/ If facility is located in private residential When mowing is needed,grass/ground Ground Cover area,mowing Is needed when grass cover should be mowed to 2 inches in exceeds 18 inches in height. in other height. areas,the general policy is to make the • pond site match adjacent ground cover and terrain as long as there is no interference with the function of the facility. Rodent Holes Any evidence of rodent holes if facility is Rodents destroyed and dam or berm acting as a dam or berm,or any evidence repaired. (Coordination with Seattle/ of water piping through dam or berm via King County Health Department) rodent holes. Insects When insects such as wasps and hornets Insects destroyed or removed from site. interfere with maintenance activities. Tree Growth Tree growth does not allow maintenance Trees do not hinder maintenance access or interferes with maintenance activities. Selectively cultivate trees such activity (i.e.,slope mowing, silt removal, as alders for firewood. vactoring or equipment movements). If trees are not interfering with access, leave trees alone. Side Slopes of Erosion Eroded damage over 2 inches deep Slopes should be stabilized by using Pond where cause of damage is still present or appropriate erosion control measure(s): where there is potential for continued e.g., rock reinforcement, planting of erosion. grass, compaction. Storage Area Sediment Accumulated sediment that exceeds 10% Sediment cleaned out to designed pond of the designed pond depth. shape and depth; pond reseeded if necessary to control erosion. Pond Dikes Settlements Any part of dike which has settled 4 Dike should be built back to the design inches lower than the design elevation. elevation. Emergency Rock Missing Only one layer of rock exists above native Replace rocks to design standards. Overfiow/Spillway soil in area five square feet or larger,or any exposure of native soil. • A-1 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 2 - INFILTRATION Maintenance Conditions When Maintenance Results Expected Component Defect Is Needed When Maintenance Is Performed General Trash &Debris See'Ponds" Standard No. 1 See'Ponds Standard No. 1 Poisonous See "Ponds" Standard No. 1 See"Ponds Standard No. 1 Vegetation 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 percolation test pit or test of facility Sediment is removed and/or facility is indicates facility is only working at 90%of cleaned so that infiltration system works its designed capabilities. according to design. Sheet Cover Sheet cover is visible and has more than Sheet cover repaired or replaced. (If Applicable) three 1/44nch holes in it. Sump Filled With Any sediment and debris filling vault to Clean out sump to design depth. Sediment and 10%of depth from sump bottom to Debris (If bottom of outlet pipe or obstructing flow Applicable) into the connector pipe. Filter Bags Filled with Sediment and debris fill bag more than Replace filter bag or redesign system. Sediment and 1/2 full. Debris �tock Filters Sediment and By visual inspection little or no water Replace gravel in rock filter. Debris flows through filter during heavy rain storms. A-2 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL • NO. 3 - CLOSED DETENTION SYSTEMS (PIPES/TANKS) Maintenance Conditions When Maintenance Results Expected Component Defect Is Needed When Maintenance Is Performed Storage Area Plugged Air Vents One-half of the cross section of a vent is Vents free of debris and sediment. blocked at any point with debris and sediment. Debris and Accumulated sediment depth exceeds All sediment and debris removed from Sediment 10%of the diameter of the storage area storage area. for 1/2 length of storage 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 1/2 length of tank. Joints Between Any crack allowing material to be All joints between tank/pipe sections are Tank/Pipe Section transported into facility. sealed. Tank/Pipe Bent Any part of tank/pipe is bent out of shape Tank/pipe repaired or replaced to design. Out of Shape more than 10%of its design shape. Manhole Cover not in Place Cover is missing or only partially in place. Manhole is closed. Any open manhole requires maintenance. Locking Mechanism cannot be opened by one Mechanism opens with proper tools. Mechanism Not maintenance person with proper tools. Working Bolts into frame have less than 1/2 inch of thread(may not apply to self-locking lids). • Cover Difficult to One maintenance person cannot remove Cover can be removed and reinstalled by Remove lid after applying 80 pounds of lift. Intent one maintenance person. is to keep cover from sealing off access to maintenance. Ladder Rungs King County Safety Office and/or Ladder meets design standards and Unsafe maintenance person judges that ladder is allows maintenance persons safe access. unsafe due to missing rungs, misalignment, rust,or cracks. Catch Basins See"Catch Basins" Standard No. 5 See "Catch Basins"Standard No.5 • A-3 I/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL In, 4 - CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Conditions When Maintenance Results Expected Component Defect Is Needed When Maintenance Is Performed General Trash and Debris Distance between debris build-up and All trash and debris removed. (Includes bottom of orifice plate is less than 1-1/2 Sediment) feet. Structural Damage Structure is not securely attached to Structure securely attached to wall and manhole wall and outlet pipe structure outlet pipe. should support at least 1,000 pounds of up or down pressure. Structure is not in upright position (allow Structure in correct position. up to 10%from plumb). Connections to outlet pipe are not Connections to outlet pipe are watertight; watertight and show signs of rust. structure repaired or replaced and works as designed. Any holes—other than designed holes— Structure has no holes other than in the structure. designed holes. Cleanout Gate Damaged or Cleanout gate is not watertight or is Gate is watertight and works as designed. Missing missing. Gate cannot be moved up and down by Gate moves up and down easily and is one maintenance person. watertight. Chain leading to gate is missing or Chain is in place and works as designed. damaged. Gate is rusted over 50%of its surface Gate is repaired or replaced to meet 0 area. design standards. Orifice Plate Damaged or Control device is not working properly Plate is in place and works as designed. Missing due to missing,out of place,or bent orifice plate. Obstructions Any trash, debris,sediment,or vegetation Plate is free of all obstructions and works blocking the plate. as designed. Overflow Pipe Obstructions Any trash or debris blocking (or having Pipe is free of all obstructions and works the potential of blocking) the overflow as designed. pipe. Manhole See "Closed Detention Systems" Standard See "Closed Detention Systems" Standard No.3. No. 3. Catch Basin See "Catch Basins"Standard No. 5. See "Catch Basins" Standard No. 5. A-4 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 5 - CATCH BASINS Maintenance Conditions When Maintenance Results Expected Component Defect Is Needed When Maintenance is Performed General Trash &Debris Trash or debris of more than 1/2 cubic No trash or debris located immediately in (Includes foot which is located immediately in front front of catch basin opening. Sediment) of the catch basin opening or is blocking capacity of basin by more than 10%. Trash or debris (in the.basin)that No trash or debris in the catch basin. exceeds 1/3 the depth from the bottom of basin to invert of the lowest pipe into or out of the basin. Trash or debris in any inlet or outlet pipe Inlet and outlet pipes free of trash or blocking more than 1/3 of its height. debris. Dead animals or vegetation that could No dead animals or vegetation present generate odors that would cause within the catch basin. complaints or dangerous gases (e.g., methane). Deposits of garbage exceeding 1 cubic No condition present which would attract foot in volume. or support the breeding of insects or rodents. Structural Damage Corner of frame extends more than 3/4 Frame is even with curb. to Frame and/or inch past curb face into the street (if Top Slab applicable). Top slab has holes larger than 2 square Top slab is free of holes and cracks. inches or cracks wider than 1/4 inch (intent is to make sure all material is running into the basin). Frame not sitting flush on top slab, i.e., Frame is sitting flush on top slab. separation of more than 3/4 inch of the frame from the top slab. Cracks in Basin Cracks wider than 1/2 inch and longer Basin replaced or repaired to design Walls/Bottom than 3 feet,any evidence of soil particles standards. entering catch basin through cracks, or maintenance person judges that structure is unsound. Cracks wider than 1/2 inch and longer No cracks more than 1/4 inch wide at the than 1 foot at the joint of any inlet/outlet joint of inlet/outlet pipe. pipe or any evidence of soil particles. entering catch basin through cracks. Settlement/ Basin has settled more than 1 inch or has Basin replaced or repaired to design Misalignment rotated more than 2 inches out of standards. alignment. Fire Hazard Presence of chemicals such as natural No flammable chemicals present. gas,oil,and gasoline. Vegetation Vegetation growing across and blocking No vegetation blocking opening to basin. more than 10%of the basin opening. Vegetation growing in inlet/outlet pipe No vegetation or root growth present. joints that is more than six inches tall and less than six inches apart. Pollution Nonflammable chemicals of more than No pollution present other than surface 1/2 cubic foot per three feet of basin film. length. • A-5 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 5 - CATCH BASINS (Continued) Maintenance Conditions When Maintenance Results Expected Component Defect is Needed When Maintenance Is Performed Catch Basin Cover Cover Not In Place Cover is missing or only partially in place. Catch basin cover is closed. Any open catch basin requires maintenance. Locking Mechanism cannot be opened by one Mechanism opens with proper tools. Mechanism Not maintenance person with proper tools. Working Bolts into frame have less than.1/2 inch of thread. Cover Difficult'o One maintenance person cannot remove Cover can be removed by one Remove lid after applying 80 lbs.of lift;intent is maintenance person. keep cover from sealing off access to maintenance. Ladder Ladder Rungs Ladder is unsafe due to missing rungs, Ladder meets design standards and Unsafe misalignment, rust,cracks,or sharp allows maintenance person safe access. edges. Metal Grates Grate with opening wider than 7/8 inch. Gate openings meet design standards. (f applicable) Trash and Debris Trash and debris that is blocking more Grate free of trash and debris. than 20%of grate surface. Damaged or Grate missing or broken member(s) of Grate is in place and meets design Missing the grate. standards. A-6 I/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 6 - DEBRIS BARRIERS (e.g. Trash Racks) Maintenance Conditions When Maintenance Resutts Expected Component Defect Is Needed When Maintenance Is Performed General Trash and Debris Trash or debris that is plugging more Barrier clear to receive capacity flow. than 20%of the openings in the barrier. Metal Damaged/ Missing Bars are bent out of shape more than 3 Bars in place with no bends more than Bars inches. 3/4 inch. Bars are missing or entire barrier is Bars in place according to design. missing. Bars are loose and rust is causing 50% Repair or replace barrier to design deterioration to any part of barrier. standards. • A-7 i/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 7 - ENERGY DISSIPATORS • Maintenance Conditions When Maintenance Results Expected Component Defect Is Needed When Maintenance Is Performed External: Rock Pad Missing or Moved Only one layer of rock exists above native Replace rocks to design standard. Rock soil in area five square feet or larger,or any exposure of native soil. Dispersion Trench Pipe Plugged with Accumulated sediment that exceeds 20% Pipe cleaned/flushed so that it matches Sediment of the design depth. design. Not Discharging Visual evidence of water discharging at Trench must be redesigned or rebuilt to Water Properly concentrated points along trench (normal standard. condition is a"sheet flow"of water along trench). Intent is to prevent erosion damage. Perforations Over 1/2 of perforations in pipe are Clean or replace perforated pipe. Plugged plugged with debris and sediment. Water P'.,ws Out Maintenance person observes water Facility must be rebuilt or redesigned to Top of'Distributor' flowing out during any storm less than standards. Catch Basin the design storm or it is causing or appears likely to cause damage. Receiving Area Water in receiving area is causing or has No danger of landslides. Over-Saturated potential of causing landslide problems. Internal Manhole/Chamber Worn or Damaged Structure dissipating flow deteriorates to Replace structure to design standards. Posts, Baffles, 1/2 or original size or any concentrated Sides of Chamber worn spot exceeding one square foot which would make structure unsound. Other Defects See 'Catch Basins'Standard No.5 See'Catch Basins"Standard No.5 0 A-8 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL • NO. 8 - FENCING Maintenance Conditions When Maintenance Results Expected Component Defect Is Needed When Maintenance Is Performed General Missing or Broken Any defect in the fence that permits easy Parts in place to provide adequate Parts entry to a facility. security. Parts broken or missing. Broken or missing parts replaced. Erosion Erosion more than 4 inches high and 12- No opening under the fence that exceeds 18 inches wide permitting an opening 4 inches in height. under a fence. Wire Fences DamagecA Parts Posts out of plumb more than 6 inches. Posts plumb to within 1-1/2 inches. Top rails bent more than 6 inches. Top rail free of bends greater than 1 inch. My part of fence (including posts,top Fence is aligned and meets design rails,and fabric) more than 1 foot out of standards. design alignment. Missing or loose tension wire. Tension wire in place and holding fabric. Missing or loose barbed wire that is Barbed wire in place with less than 3/4- sagging more than 2-1/2 inches between inch sag between posts. posts. Extension arm missing, broken,or bent Extension arm in place with no bends out of shape more than 1-1/2 inches. larger than 3/4 inch. Deteriorated Paint Part or parts that have a rusting or scaling Structurally adequate posts or parts with or Protective condition that has affected structural a uniform protective coating. • Coating adequacy. Openings in Fabric Openings in fabric are such that an 8- No openings in fabric. inch-diameter ball could fit through. • I I A-9 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL 110. 9 - GATES Maintenance Conditions When Maintenance Results Expected Component Defect is Needed When Maintenance Is Performed General Damaged or Missing gate or locking devices. Gates and locking devices in place. Missing Members Broken or missing hinges such that gate Hinges intact and tubed. Gate is working cannot be easily opened and closed by a freely. maintenance person. Gate is out of plumb more than 6 inches Gate is aligned and vertical. and more than 1 foot out of design alignment. Missing stretcher bar,stretcher bands, Stretcher bar, bands,and ties in place. and ties. Openings In Fabric See "Fencing"Standard No.8 See"Fencing" Standard No.8 • A-10 1/'90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL • NO. 10 - CONVEYANCE SYSTEMS (Pipes & Ditches) Maintenance Conditions When Maintenance Results Expected Component Defect Is Needed When Maintenance is Performed Pipes Sediment&Debris Accumulated sediment that exceeds 20% Pipe cleaned of all sediment and debris. of the diameter of the pipe. Vegetation Vegetation that reduces free movement of All vegetation removed so water flows water through pipes. freely through pipes. Damaged Protective coating is damaged; rust is Pipe repaired or replaced. causing more than 50%deterioration to any part of pipe. Any dent that decreases the cross section Pipe repaired or replaced. area of pipe by more than 20%. Open Ditches Trash &Debris Trash and debris exceeds 1 cubic foot Trash and debris cleared from ditches. per 1,000 square feet of ditch and slopes. Sediment Accumulated sediment that exceeds 20% Ditch cleaned/flushed of all sediment and of the design depth. debris so that it matches design. Vegetation Vegetation that reduces free movement of Water flows freely through ditches. water through ditches. Erosion Damage to See"Ponds"Standard No. 1 See "Ponds" Standard No. 1 Slopes Rock Lining Out of Maintenance person can see native soil Replace rocks to design standard. Place or Missing (If beneath the rock lining. Applicable) • Catch Basins See'Catch Basins"Standard No.5 See "Catch Basins"Standard No.5 Debris Barriers See "Debris Barriers"Standard No.6 See "Debris Barriers" Standard No.6 (e.g.,Trash Rack) A-11 I/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL 11 - GROUNDS (Landscaping) Malntenance Conditlona When Malntenance Rasufts Expected Component Defect Is Needed When Malntenance Is Performed General Weeds Weeds growing in more than 20%of the Weeds present in less than 5%of the (Nonpoisonous) landscaped area (trees and shrubs only). landscaped area. Safety Hazard Any presence of poison ivy or other No poisonous vegetation present in a poisonous vegetation. landscaped area. Trash or Litter Paper,can, bottles,totalling more than 1 Area clear of litter. cubic foot within a landscaped area (trees and shrubs only)of 1,000 square feet. Trees and Shrubs Damage Limbs or parts of trees or shrubs that are Trees and shrubs with less than 5%of the split or broken which affect more than total foliage with split or broken limbs. 25%of the total foliage of the tree or shrub. Trees or shrubs that have been blown Tree or shrub in place free of injury, down or knocked over. Trees or shrubs which are not adequately Tree or shrub in place and adequately supported or are leaning over,causing supported; remove any dead or diseased exposure of the roots. trees. • A-12 I/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 12 - ACCESS ROADS/EASEMENTS Maintenance Conditions When Maintenance Results Expected Component Defect is Needed When Maintenance Is Performed General Trash and Debris Trash and debris exceeds 1 cubic foot Trash and debris cleared from site. per 1,000 square feet, i.e.,trash and debris would fill up one standard size garbage can. Blocked Roadway Debris which could damage vehicle tires Roadway free of debris which could (glass or metal). damage tires. Any obstructions which reduce clearance Roadway overhead clear to 14 feet high. above road surface to less than 14 feet. Any obstructions restricting the access to Obstruction removed to allow at least a a 10-to 12-foot width for a distance of 12-foot access. more than 12 feet or any point restricting access to less than a 10-foot width. Road Surface Settlement, When any surface defect exceeds 6 Road surface uniformly smooth with no Potholes, Mush inches in depth and 6 square feet in area. evidence of settlement,potholes,mush Spots,Ruts In general,any surface defect which spots,or ruts. hinders or prevents maintenance access. Vegetation in Road Weeds growing in the road surface that Road surface free of weeds taller than 2 Surface are more than 6 inches tall and less than inches. 6 inches apart within a 400-square-foot area. Shoulders and Erosion Damage Erosion within 1 foot of the roadway more Shoulder free of erosion and matching Ditches than 8 inches wide and 6 inches deep. the surrounding road. • Weeds and Brush Weeds and brush exceed 18 inches in Weeds and brush cut to 2 inches in height or hinder maintenance access. height or cleared in such a way as to allow maintenance access. A-13 I/90