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Home My WebLink About03651 - Technical Information Report V1� 1 NA Schweikl& Associates, llc P M Civil Engineering, Project Management, & Consulting TECHNICAL INFORMATION REPORT FOR BECLAN PLACE MINOR AMENDMENT PROJECT NO : 12183 JULY 2012 , AUGUST 2012 PREPARED FOR: QUADRANT HOMES, INC. 14725 SE 36TH, STE. 100 BELLEVUE, WASHINGTON 98006 PREPARED BY: BRANT A. SCHWEIKL, P.E. SCHWEIKL AND ASSOCIATES, PLLC. 1945 SOUTH 375TH STREET FEDERAL WAY, WA 98003 (253) 226-4508 1 12183_TIR_MA_120819.doc 34751 TECHNICAL INFORMATION REPORT FOR BECLAN PLACE Minor Amendment Renton, Washington 98059 July 2012, August 2012 Prepared for: ii, AA-SCS QUADRANT HOMES, INC. . • 'IF 14725 SE 36TH STE. 100 i ..1 �;_ ---7�.'*\;e,' BELLEVUE, WASHINGTON 98006 f "'` i f- �,yr Prepared by: -.\�;r .:a.•/ ts' Brant A. Schweikl, P.E. REPORT #12183 S. M. I - "I hereby state that this Storm Drainage Report for Beclan Place—Minor Amendment has been prepared by me or under my supervision and meets the standard of care and expertise which is usual and customary in this community of professional engineers. I understand that the City of Renton does not and will not assume liability for the sufficiency, suitability or performance of drainage facilities prepared by me." This analysis is based on data and records either supplied to, or obtained by, Schweikl and Associates,pllc. These documents are referenced within the text of the analysis. The analysis has been prepared utilizing procedures and practices within the standard accepted practices of the industry. 2 12183_T[R_MA_120819.doc The Plat of Beclan Place Parcel Numbers 1523059064, 1523059065, 1523059090 and 1523059116 TECHNICAL INFORMATON REPORT Minor Amendment TIR Section 1 -Project Overview The following project narrative is provided to the City of Renton as part of the Minor Amendment and construction drawing submittal process for the approved Beclan Place development project. The project was previously designed and received Preliminary Plat and Engineering approval to the R-5 zoning standards and the 2005 King County Surface Water Design Manual (KCSWDM).At the time of original engineering plan approval the City was utilizing the 2005 KCSWDM for flow control facilities in the Level 2 Flow Control basins. The proposed Minor Amendment storm drainage revisions are designed to the approved and vested 2005 KCSWDM. Due to the non-existent and stagnant housing industry over the last four years the project sat without any potential demand or purchasers willing to invest in a slow and flooded market. Now with the inventory of available lots finally shrinking in some key high demand markets the property is now in higher demand in a modified market where the land prices have drastically decreased and the size and cost of the current saleable home range has also decreased. Therefore certain financial parameters that were in affect at the time of initial preliminary plan and engineering design are no longer applicable to the current market and now require discrete revised approaches primarily to the cost of the overall stormwater flow control facilities that were affective in the past. For example the high cost of an underground detention vault was previously warranted mainly due to the high land values, but currently the cost of cast in-place concrete retaining vault walls and the precast prestressed hollow core top slab panels and the cost of having a substantial sized crane onsite for placement of the slabs is no longer financially feasible in the current market land prices. The proposed Minor Amendment modifications to the Beclan Place project that Quadrant Homes, Inc. (QH) is requesting stem primarily around the elimination of the costly underground concrete detention/wetvault and replacing it with an open detention/wetpond with one cast in place concrete retaining wall along the east Tract boundary that will eliminate one buildable single-family lot(Preliminary Plat Lot#10) and reduce the plat to a total of 30 lots.. Quadrant Homes also wishes to utilize the full allowable impervious coverage as dictated under the R-5 Zoning(55%impervious) as the design parameters for the flow control facility. Previously the approved design had proposed a 5% reduction in the impervious coverage for flow control sizing. The allowable impervious coverage is 55%per the R-5(R-4)zoning code. 3 12183 TIR MA 120819.doc Per City of Renton revision in the application of the 2005 KCSWDM criteria the project has implemented individual on lot Stormwater BMP's per Appendix C of the 2005 KCSWDM. The project is required to apply individual lot stormwater BMP's for 10%of the individual lot impervious area as calculated for the 55% impervious per the R-5 zoning. The developer has chosen to implement Limited Infiltration as the on lot individual stormwater BMP, see Limited Infiltration Table, below and on Sheet C-11 of the Engineering Plans. The Limited Infiltration BMP utilizes the Associated Earth Sciences, Inc. (AESI) August 15, 2012, Technical Memorandum, USDA Soil Classification, that verifies that the onsite soils area classified as Sandy Loam and therefore the length of limited infiltration trench shall be designed for the Sandy Loam at 125 if of trench per 1000 sf of impervious area. See AESI Technical Memorandum at the end of the Geotechnical Report Section. The Limited Infiltration BMP stipulates that the 10% of the impervious area per lot shall be taken as 50% impervious and 50% lawn. Therefore we were allowed to reduce the overall site impervious and recalculate the required project detention storage volume for the detention/wetpond flow control facility within Tract A. Along with the flow control concept revision Quadrant Homes is proposing the following associated Minor Amendment revisions to the approved preliminary plat and engineering drawings; • 1. Rotate original Lots 1, 2, 3 and 4 so that the front off of NE 2nd Place (1&2) and NE 2nd Street (3&4), respectively. Removes the four (4) individual single-family off of the Jericho Ave SE right-of-way (ROW) and will improve traffic flow and reduce potential accidents due to the elimination of backing movements onto the Jericho ROW. 2. The sanitary and domestic water services located on Jericho Ave SE are proposed to be eliminated with the rotation of the lots previously fronting on Jericho Ave SE. This should reduce the total length of traffic restriction necessary to install public infrastructure improvements. 3. Demolition of the existing home and driveways located on (Preliminary Plat) Lot 21 and also rotating the lot frontage internally. The lot will be decreased in size and the excess lot width will be distributed over minor amendment lot numbers 21-26. 4. Minor Amendment Lots 16 & 17 were shortened in length (east-west) and widened (north-south) holding the southern lot line of Lot 16 to allow for the rotation of Lots 1-4 in Item 1 above. Both maintain an excess of 7200 sf in size. 5. QH requested to save addition trees onsite that were not previously thought to be capable of retaining due to the fact that the original developer was not able to apply a specific home footprint as QH's has specifically detailed out with their extensive company planning and foot print layout. 4 12183 TIR MA 120819.doc 6. The proposed street light plan relocates the streetlights that were on the north side of NE 2nd Place to the south side of the public ROW to allow for a more efficient routing of the dry utilities onsite. 7. The original lot line between lots 28-30, 27-28 and 26-27 were revised slightly to allow for more efficient placement of the QH standard home footprints. 8. The proposed water system was lengthened to accommodate the rotation Lots 1,2,3,4 and 21, so that the services were directly connected perpendicular to the main instead of weaving longer services to the lots. Both the mains in NE 2nd Place and NE 2nd Street were affected. 9. The proposed SSMH#4 was relocated eastward to accommodate the rotation of Lots 1,2,3,4 and 21. 10. The project grading plan was revised to provide larger flat building pad per QH building standards. Proposed building pads were also lowered to generate additional beneficial cut material to provide a closer balance the site earthworks and allow for placement of existing substantial topsoil generated by the grading process to be placed onto of the building pads lawn and landscaped areas. 11. QH is proposing to add a 35'x35' triangular monument easement at the southern side of the intersection of Jericho Ave SE and NE 2"d Place that includes a plat monument sign, landscaping and irrigation meter and system to be maintained by the Homeowners Association. 12. Storm Drainage revisions include removing the internal lot conveyance system that existed between lots 16 and 20 and extended to the detention vault. This conveyance system is downstream of CB#12A and extends to the Detention Tract A. The main 12" SD pipe downstream of CB#9 to CB#8 will also be eliminated. The above SD conveyance system will be redirected westward within the NE 2nd Place public ROW and then combined with the proposed storm drainage system in Hoquiam Avenue that is now being lowered and Type 2 CB's added to accommodate the required slope and depth of the proposed line. The roof drain service lines and stubs associated with the previous internal SD conveyance line now removed will be relocated along the SD conveyance system within the public ROW. There are minor storm system conveyance system revisions proposed due to the minor lot line revisions, additional retained trees and the revised flow control facility concept proposed. CB#16 and the associated 1213 conveyance pipe to the northern plat boundary was relocated to accommodate the translation of proposed Minor Amendment lot lines and to more efficiently located the proposed conveyance pipe off of the proposed property line for maintenance access. Type 1 CB#6 was relocated slightly so that it would not be located within the frontage of one of the now identified private single- family driveways on NE 2nd Street. 5 12183 TIR MA 120819.doc Besides the above proposed Minor Amendment revisions to the approved preliminary plat and engineering plans a large majority of the proposed single-family utility services and wet utility services have been relocated to more efficiently serve the proposed lots and single-family structures to meet QH standards, retain additional existing trees and be consistent with the revised minor lot line movement. Preliminary Plat Overview The approved project is located at the northwest corner of the intersection of NE 2nd Street and Jericho Avenue NE. The proposed project consists of four existing parcels, (Parcel Numbers 1523059064, 1523059065, 1523059090 and 1523059116)which vary in size from .67 acres to 4.1 acres. Total area of the four parcels is 308,616 square feet(7.08 acres). The current City of Renton zoning classification is R-4 Single-Family Residential. Since the site was annexed into the City of Renton as part of the Mosier Annexation Area, it falls under Condition #13 of the R-4 zoning code. This allows the site to develop to a maximum code density of 5 dwelling units per acre instead of the normal 4 dwelling units per acre allowed for standard R-4 zoning. At present there is an existing residence on parcel 1523059116. The other three parcels are vacant, a former residence on parcel 1523059064 having been previously demolished. Except for the landscaped area surrounding the existing residence, the remainder of the site is undeveloped and/or non-maintained. Most likely the site had been cleared or logged at some point in time, and the remnants of a pasture exist in the southern portion of the property. Adjacent to the western property line in the northwest corner of the site is a wetland. This wetland is part of a larger wetland that extends off the property to the west. The northern and western areas are also more wooden, with a mixture of maple, cedar, fir and hemlock trees. The approved project site is bounded on three sides by public right-of-ways. To the east is Jericho Avenue NE, the most prominent street addressing the site. To the south is NE 2"d Street, a less used residential street that currently dead ends a block west of the site. The NE Hoquiam Avenue right-of-way bounds the project site to the west and is unimproved. The project proposes to develop Hoquiam Avenue to provide the western region of the site access south to NE 2nd Street. The West Coast project, directly west of the right-of-way, will share in the development of Hoquiam Avenue and coordination between the projects has already installed 20 feet of asphalt pavement and a raised asphalt wedge curb along the eastern edge of the asphalt surface. The surrounding parcels are all zoned single-family residential. Current land uses either reflect that or remain undeveloped. Several established single-family residential plats exist immediately adjacent to the project. Two more, the West Coast project mentioned above, which is in the design stage, and the Shy Creek project, already building directly to the south, will add to that. The original Preliminary Plat proposed to plat the four existing parcels into 31 single- family lots in the R-4 Residential, and is vested to the R-5 standards. The existing residence was proposed to remain on what is to become the new Lot 21. The Minor 6 12183_TIR_MA_I20819.doc Amendment proposal now is intending on demolishing the existing single-family residence on Lot 21. Two tracts will also be created, one to preserve the wetland and its buffer, and another to house the storm drainage detention/water quality facility. The project will also dedicate area to the City of Renton for public right-of-way. A proposed internal road with a 42 foot wide right-of-way section, and a small piece of the south east corner of the site (outside of the City required 15 foot radius) will be dedicated. All proposed lots will front and access public right-of-ways directly except for lots 30 and 31. They will access a public right-of-way via a joint use access easement and tract. All lots meet the 60 foot minimum width requirement and the 7,200 square foot minimum size requirement. The lots range in size from 7,230 square feet (Lot 16) to 9,062 square feet(Lot 1). The overall density for the finished project becomes 4.77 dwelling units per acre. The ballpark opinion of probable cost of construction for site improvements is $886,000 and the opinion of probable fair market valve for the completed project is $19.5 million, assuming the finished dwelling units will be sold for an average price of $650,000. All lots will receive their utility services underground from their respective frontage of the adjacent right-of-ways or private access tract. All lots will be connected to the public sanitary sewer, including a new service to the existing residence on Lot 21. Their private septic system on Lot 21 will be abandoned. The proposed domestic water system will be designed by King County Water District #90 and Roth Hill Engineers, the district's consulting engineer. The project proposes to install a new 12"0 water main within the new NE 2nd Place public ROW and dead ends prior to reaching the existing water main in Jericho Avenue which is part of another pressure zone. The new 12"0 water main will be installed because of the project having to provide a 1000 gpm of fire flow at two separate hydrants due to the fact that the homes projected for installation will be larger than the 3600 sf threshold. The water main will be downsized to a standard 8"0 main when the modeling program indicates that the 12"0 pipe is no longer required to meet the fire flow requirements. The water main will connect onto West Coasts newly installed 8"0 water system at the intersection of NE 2nd Place and Hoquiam Ave. This water main will provide up to four fire hydrants along the internal NE 2nd Place and the majority of the domestic water service for the project. A water line, teed south at Hoquiam, provides services and a fire hydrant to lots along that right-of-way. Extending the water line being installed by Shy Creek in the NE 2nd Street right-of-way east, will provide services and a fire hydrant to the southeast corner of the project. A ten foot wide utilities easement will extend from the public right-of-ways into all lots fronting them. This will allow for the placement of dry utilities. The proposed offsite street improvements for the project include the following. Hoquiam Avenue NE will be developed to a 20-foot width pavement section with curb, gutter and sidewalks (half street improvements by Beclan Place) on the east half of the right-of-way due to the lack of available right of way on the west half of the alignment. The 20-feet of pavement will be based off the eventual center of the ROW and will offset the eastern curb line on Hoquiam Avenue NE four feet from the curb lying to the south NE 2nd Street. 7 12183_TIR_MA 120819.doc Right-of-way improvements will also be made to NE 2nd Avenue and Jericho Avenue NE. Full half street improvements will be made to NE 2nd Street including curb, gutter and sidewalks, and a widening to 16 foot wide lane paving from the new street widening that was installed by Shy Creek. Curb, gutter, sidewalk and planter strip will also be added adjacent to our frontage along Jericho Avenue with the curb line being placed at 18 feet from the centerline of the ROW. The conceptual grading plan as depicted has 12,148 CY of Cut and 14,000 CY of Fill (unstriped). The project is therefore determined to be a Fill site, and must have material imported from an offsite location. The final grading plan will attempt to provide an earthwork balance and reuse portions of the existing topsoil in non-structural onsite fill locations to reduce the amount of material needed to be transported onto the site. The project soils as mapped are found to be ground moraine deposits consisting of unsorted mixture of clay, silt sand and gravel, known commonly as glacial till. The glacial till is covered by approximately 1 to 1.5 feet of topsoil and 1 to 3.7 feet of weathered soil, consisting of medium dense silty sand with gravel (see Geotech Report). It is the unusual thickness of the topsoil layer that is creating the high earthwork quantity numbers. In light of maximizing the number of lots that can be created under the R-4 Single Family Residential Zoning Code, most of the trees within the developed area will be removed to allow for placement of the structures (See Tree Inventory Plan). Special care and considerations (grading, wetland tract) have been taken to ensure that certain trees will remain. New trees will be planted to meet the City of Renton's requirements (see Landscape Plan). All efforts will be taken to save any other existing trees or landscape features within the project boundary area that do not directly affect construction of the proposed new residences. The 2005 King County Surface Water Design Manual (KCSWDM) is the storm drainage regulatory manual adopted by the City of Renton. In accordance with the 2005 KCSWDM, Figure 1.1.2.A Flow Chart for Determining Type of Drainage Review Required, was utilized to determine the type of drainage review that the project is subject too. The results of the storm drainage review type was determined to be a Full Drainage Review,because the project proposes greater than 10,000 sf of new impervious surface and greater than 7000 sf of land disturbing activity. The King County Soils Survey Maps provided by the United States Department of Agriculture Soil Conservation Service were reviewed to determine the soil characteristics with the project sub basin with respect to the soils susceptibility to landslides and erosion and its capability for groundwater recharge and surface water runoff. The review indicated that the existing site soils are typical Alderwood(AgC) glacial till over lain by a 12"to 18"layer of topsoil. TIR Section 2 —Conditions and Requirements The project will receive its complete plat conditions and requirements once the plat has completed it Preliminary Plat submittal process,Hearing and SEPA review. The 8 12183_TIR_MA_120819.doc preliminary plat submittal has been created with respect to the City of Renton Municipal Code and the 2005 King County Surface Water Design Manual(KCSWDM). The project is located in a Level 2 Flow Control basin and is required to provide Basic Water Quality Treatment. TIR Section 3—Offsite Analysis The project's Level One Downstream Analysis was conducted on Saturday November 11' 2006. The weather at the time of the downstream analysis field investigation was partly mostly cloudy and approximately 45 degrees. There had been measurable precipitation in the past couple of days and there was runoff visible in most areas of the downstream. Resource Review The available resources were reviewed and a summary of the resource research follows: The project does not lie in either a FEMA flood plain, a Critical Drainage Area or an adopted Basin Plan. The King County Sensitive Areas portfolio was reviewed with the use of the iMap website and there area no sensitive areas located onsite. There are a few sensitive areas in the surrounding vicinity. 1.) Downstream, south of SE 138th Street there is an area of SAO Erosion and Landslide Hazard areas associated with the downstream stream corridor where the stream descends to the Cedar River Valley. The King County WLR Drainage Complaints located in the immediate vicinity downstream properties were researched and a request for a description of the downstream storm drainage complaints was requested. There are some complaints to the west of the projects SW property corner that lie along the drainage features that passes through the adjacent developments to the west along NE 2"d Street. These parcels currently would only be affected by runoff from our proposed project predominately during a major storm event if the culvert inlet at the northeast quadrant of the NE 2"d Street and Hoquiam Ave NE intersection was to clog. The northern roadside ditch along NE 2"d Street does not convey water to the area to the west along NE 2' Street. There is also a parcel to the south where Hoquiam Ave NE turns westward and becomes SE 136th Street where the channelized stream opens up into a natural stream bed in an undeveloped parcel. The complaints will be further defined in the Final TIR once the available Drainage Complaint information has been obtained from King County. The existence of one wetland onsite was noted during the wetland reconnaissance by Alder NW and in their wetland report. Wetland"A",a 4,312 sf City of Renton Category 2 wetland with accompanying 50-foot buffer was located in the very northeast corner of the project. The wetland will not be altered in any manner and the 50 foot buffers will remain intact,no wetland buffer averaging is proposed. 9 12183_TIR_MA_120819.doc Field Investigation The project site and downstream existing storm drainage infrastructure was inspected on Saturday November 11, 2006 at 9:30 am. The project's upstream storm drainage infrastructure includes the Jericho Ave NE right-of-way that has no defined storm drainage or open ditch system along the western shoulder of Jericho Ave NE. Therefore the runoff developed from the high point in the basin is either sheet or shallow flows the general flows in the northeast to southwest direction. The centerline of Jericho Ave NE is an offsite basin boundary line for runoff coming onto the project site. Therefore the eastern half of the Jericho Ave NE right-of-way does not contribute to the project and there are no cross culverts connecting the flows east of Jericho to the west and our basin. The minimal amount of roadway infrastructure improvements along the western property frontage will be conveyed to the detention facility as instructed by the City of Renton's first set of review comments and the north end of the existing culvert across 2"d Avenue NE will be plugged with concrete and abandoned in place. Generally northeast to southwest gradient is also consistent with our proposed project site,with the exception of a small portion of the northwest panhandle of the parcel that contributes storm drainage to existing Wetland"A"in the northwest corner of the parcel. About two thirds along the Jericho Ave NE frontage from the northeast property corner a shallow roadside ditch starts to manifest itself as it travels further to the south. This small reach of roadside ditch conveys water to the intersection of NE 2' Street and underneath NE and south of the site outside the projects basin downstream path. The Hoquiam Ave. NE existing 30 half ROW(eastern)on the western boundary of the project is an unopened system existing public ROW. The southern parcel boundary is adjacent to the existing 60-foot public ROW and the road section incorporates a roadside ditch that collect the northern half of the 2"d Ave.NE ROW and the onsite sheet flows from the project onsite basin. The roadside ditch conveys runoff to the existing 8"0 culvert at the northeast quadrant of the NE 2"d Street and Hoquiam Ave.NE. The north boundary of the site is adjacent to single structure low density residential development with substantial remaining tree canopy and under brush in the western portions on the adjacent parcels. The downstream investigation commences at the natural point of discharge for the project at the northeast quadrant of the northeast quadrant of the intersection of NE 2"d Street and the Hoquiam Ave NE, (PT"A"). PT"A" is the western terminus of the roadside ditch along the north edge of the NE 2"d Street ROW and collects a majority of the projects existing site runoff. The runoff is prevented from being conveyed to the west by some fill material what may have been placed by some of the surrounding downstream residents. It is difficult to determine the actual past history of the design drainage patterns. The adjacent private driveway to the west has a 12"0 steel culvert that is plugged with 0.7' of material on the inlet side and 0.6' plugged on the outlet end that shows no evidence of stormwater runoff flow to the west. From PT"A"the site runoff is conveyed in 32 if of 8"0 steel culvert at±3.2%to PT"B" at the southeast quadrant of the intersection and discharges into the eastern roadside ditch. The eastern roadside ditch is 10 12183_TIR MA 120819.doc approximately 2.5 feet wide at the bottom of the ditch, with 2:1 side slopes and is heavily vegetated with tall grasses and blackberry. The slope of the ditch is±2.0%with a depth of approximately 1.5 feet. At PT"C",601f downstream the eastern roadside ditch is still present, at an approximate slope of±2.0%and the centerline of the paved traveled way of the Hoquiam Ave NE is the western most edge of the sub basin draining to the ditch. The ditch continues southward to PT"D", downstream 210 lf,the ditch has shallow flow a longitudinal slope of±1.1% and is approximately 1.4' deep. At PT"E",286 if downstream, is flow is approximately 1' wide and 3" deep and this is the point at where the blackberry vines dissipate. The ditch bottom is heavily grassed. At PT"F", 3921f downstream,near the intersection with SE 133`d Street,the flow is a trickle, 1' wide, 2:1 side slopes, is approximately 1.2' deep. The ditch contains significant leaf fall and organic clutter. At PT"G", 540 lf downstream,the ditch bottom is approx. 2.3' wide and newly cleaned and maintained with less vegetation and is at a slope of±3.0%and is approximately 1.2' deep. The flow in this reach of the ditch is at a trickle. PT"H",673 if downstream, is the point at which the ditch exhibits the clean and maintained appearance ends. The ditch bottom is approximately 3.0' wide and 1.3' deep. There is an erosion control roll 30-feet upstream,there is no evidence of erosion in the swale at this point. At PT"I",686 lf downstream,there is an 18"0 CMP beveled end pipe inlet with aluminum debris barrier. At this point the ditch flows are taken into a tight lined public conveyance system. The entrance to the conveyance system is heavily covered with blackberry and leaf clutter. At PT"J", 7401f downstream, there is an area where there appears to have been runoff over flow from one of the Shy Creek temporary erosion control basin that most likely overflowed from the facility during a period of heavy precipitation. The flows enter the roadside ditch that recommences after PT"I". The ditch slope is±1.7%and there is some evidence of scour on the eastern side slopes of the ditch were most likely caused by the overflow for the Shy Creek temporary erosion control facility. At PT"K", 8601f downstream,there is a SDMH at the edge of the edge of pavement. There is no flow in the ditch and is also the end of the gravel that has been scoured in the ditch from the overflow from PT"I". The ditch has heavy leaf clutter in the ditch. At PT"L", 1000 if downstream,the minor ditch flow combines with a significant stream flow for the Shy Creek residential project that enters into the former alignment of the roadside ditch after running parallel to the roadside ditch for approximately 50 down stream. The combined flow is clean and clear and 4-5' wide, 7"to 14" and flowing at a 1'/sec velocity. At PT"M", 10151f downstream,there is a SDMH at the edge of the edge of pavement and a 24"0 N-12 with aluminum debris barrier located in the northern ditch line of SE 135th Street that conveys storm water runoff from the small drainage tributary that is travels from north to south through the Puget Colony Homes development and then enter our downstream path at this point. At the time of the downstream analysis there was no flow at the inlet. At the south side of SE 135th Street 11 12183 TIR_MA_120819.doc there is a 12"0 concrete pipe that is 50%clogged and has approximately 1.6' of available head prior to the overflow. The pipe conveys flows from the south side of the SE 135 ' Street ROW to the main conveyance trunk in the Hoquiam Ave NE ROW. At PT"N", 1138 if downstream,the stream along the eastern edge of Hoquiam is 6' wide, 1.5' deep with a gravel bottom and leaf clutter. The slope of the stream at this point is±1.7%. At PT"O", 1263 if downstream,there is a SDMH along the main trunk line that runs parallel to the stream at the eastern road shoulder. The eastern bank of the stream has been cleared (1:1 slope),the western bank slope is vegetated and is approximately 2:1. The stream is 6' wide, flowing clear and 12"to 18"deep. The stream bed is gravel and cobbles. Upon reaching PT"P", 13391f downstream,the stream flow enters 54"0 CMP wide culvert @±6.7%that has approx. 74"of available head prior to overflow. The entrance to the culvert is heavily protected with 12"-6"rip rap to a depth of 18 inches and has a temporary 2"0 discharge pipe from the detention facility just east of the stream. At PT"Q", 13841f downstream,the stream emerges from the 54"0 CMP culvert along with the 30"0 CMP tight lined conveyance trunk line from the Hoquiam Ave NE ROW and an independent 12"0 N-12 pipe(no flow)from the Hoquiam ROW. The three outlets combine into a clean flowing 12-foot wide forested stream corridor that continues to the south. The stream bead does not show any evidence of erosion scour or excessive sediment transport at the outlets. TIR Section 4—Flow Control and Water Quality Analysis and Design Minor Amendment Flow Control and Water Quality Analysis and Design The written conclusions from the Pre-application meeting conducted at the City of Renton and the approved Preliminary Plat Hearing conditions indicates that the Plat of Beclan Place will be required to provide Flow Control to the Level 2 Flow Control levels and basic water quality as promulgated in the 2005 King County Surface Water Design Manual (KCSWDM). As approved and vested the Minor Amendment revisions to the stormwater aspects of the project shall be pre the 2005 KCSWDM. The approved storm drainage plan will includes recharge of the existing Wetland A. The roof storm drains and pervious lawn surfaces from Lots 29 and 30 will be directed to discharge to the wetland buffer in Tract B. (See separate document, Wetland Hydrology Recharge Report for Wetland A). All of the other storm water runoff from the project will be collected and conveyed to the detention/water quality facility, including the minor street infrastructure widening and installation of concrete curb, gutter and sidewalk on Jericho Ave NE ROW. The controlled discharge from the detention/wetpond in Tract A will be conveyed offsite to a Type 2 catch basin that was installed by Shy Creek at the southeast intersection of Hoquiam and NE 2nd. Beclan Place provided construction funds to Shy Creek to lower their proposed public storm drainage conveyance line in Hoquiam Ave NE to 12 12183 TIR MA 120819.doc accommodate the proposed depth of our discharge pipe from the previously approved underground detention and water quality facility at the NE quadrant of the intersection. The proposed revision to make the facility an above ground open detention/wetpond will not affect the current discharge point or elevation of that connection. Attenuated flows from flow control facility will be conveyed southward down the newly installed public storm drainage conveyance system in Hoquiam Ave NE towards Maplewood Creek. The project proposed existing project drainage basin(PREDEV) includes 7.25 acres of existing area with a forested till existing land use covering. Prior to the implementation of the onsite individual Lot BMP's the proposed developed basin(DEV)was a 7.25 acre basin that is comprised of 4.20 acres of impervious area and 3.05 acres of lawn. And after the implementation of the onsite individual Lot BMP's (Limited Infiltration)the developed basin(DEV) is a 7.25 acre basin that is comprised of 4.05 acres of impervious area and 3.20 acres of lawn. The allowed percentage of impervious surface per R-5 zoning per lot is 55%and QH's wishes to design to this standard to accommodate three car garages of some of the lots where possible (See Attachment C, 12183 Detention Basin Calcs). The developed basin also contains the two concrete driveways for Lots 29 &30 that drain to the private access drive instead of the Wetland in Tract B for recharge of the wetland since the driveways are subject to vehicular traffic/parking and the surfaces require water quality treatment. The KCRTS hydrologic modeling software that the 2005 KCSWDM requires engineers to utilize in sizing of flow control facilities (detention facilities)will be used to determine the project detention requirements. At the time of original approved engineering design the City of Renton had adopted the 2005 KCSWDM as the City's storm drainage manual for projects that require Level 2 flow control. We utilized three(3) orifices(maximum allowed by the software) and one (1)notched weir(maximum allowed by the software) in the revised Minor Amendment sizing of the facility due to our extended experience with the software and it's inherent challenges in obtaining the compliance with all of the Duration Comparison Analysis cutoff parameters required. The proposed KCRTS detention pond sizing's at the available 7.30 feet of total head available head in the proposed pond. Below are the specifics for our proposed flow control Comparison Analysis 1. First Cutoff having a percentage change of equal to or less than 0.00.... we have-3.8% 2. At least half of the cutoffs must be 0.00 or negative ..... we have 7 of 14 complying 3. The maximum excursions shall be less than 10% at all cutoffs..... The maximum positive excursion and maximum negative excursion are 9.9% and-8.8% respectively. 13 12183 TIR MA 120819.doc Therefore we have met all of the Comparison criteria per the 2005 KCSWDM. The proposed open detention/wetpond was designed to maximize the available storage volume after taking into account the loss of Lot 10 into the tract and rotation of the 5 lots originally fronting on Jericho Ave SE and their associated affect upon the overall lot configuration. The open detention/wetpond has 83,076 cubic feet of available storage volume (See Attachment A, 12183 MM Pond) at the proposed peak stage of 7.30 feet as calculated by the KCRTS design pond calculations. The KCRTS modeling program for the design (trapezoidal pond (POND BMP1..89'x89', 2:1 side slopes) indicates that for Level 2 Flow Control standards the project will require 78,869 cubic feet of storage at peak reservoir stage of 7.30 feet above outlet(399.00) or maximum ponding elevation of 406.30. (See Attachment B, 12183 Stage Calcs) Therefore we have approximately 4,207 cubic feet of additional live storage volume available or an addition 5.33% of the required 78,869 cubic feet volume built into our proposed Minor Amendment flow control facility design Wetpond Water Quality Calculations The permanent water quality volume for the wet vault is calculated with respect to Section 6.4.1.1 of the 2005 KCSWDM for the Basic wetpond criteria. Wetpool volume = Vb=f*(0.9A, + 0.25Atg+0.10Atf+0.10A0*(R) Where, Vb=wetpool volume (cf) f=volume factor A, = area of impervious surface (sf) Atg= area of till soil covered with grass (sf) Att.= area of till soil covered with forest (sf) Ao= area of outwash soil covered with grass or forest (sf) R =rainfall from mean annual storm event(inches) (refer to attached Figure 6.4.1.A KCSWDM) Therefore, Vb=3[(0.9(175,111)+ 0.25(132,858))*(0.47)] Vb=26,905 cf Required Vb Provided =34,460 cf (See Attachment A, 12183 MM Pond) The water quality volume in Cell 1 is designed at 5.00 feet deep water quality treatment, plus with one foot of additional available sediment storage to elevation 391.00. At a depth of 5.00 feet the water quality cell, Cell 1, will encompass approximately 29.72% of the combined water quality bottom area/volume. The remainder of the wetpond, Cell 2, 14 12183_TIR_MA_120819.doc will maintain the 7.00 foot WQ depth(WQ bottom elevation 392.00),plus an additional one foot sediment storage to the cell bottom elevation 391.00. The five foot wide earthen berm separating the Cell 1 and Cell 2 shall be designed with non-free draining material and be keyed into the compacted base of the detention pond. The top of the berm elevation is 398.00 (1 foot below the WQ storage stage of 399.00) and shall have a 5.00 foot wide equalization spillway provided with a top of spillway elevation of 397.00. The equalization spillway will address the initial seasonal filling of Cell 2 to prevent any stormwater from passing over the earthen portions of the separation berm and preserve the integrity of the berm over time. The equalization spillway will be constructed with 12 inches of rip rap with a non-woven geotextile fabric placed under and on the sides of the rip rap pad to prevent migration of soil and fines in to the rip rap. The equalization spillway should not allow any short circuiting of the water quality treatment during the wetpond equalization and it provides protection above and beyond the KCSWDM. *** 15 12183 TIR MA 120819.doc **Below is the Original Flow Control and Water Quality Analysis and Design****** --****Section from the approved TIR for reference.******** The written conclusions from the Pre-application meeting conducted at the City of Renton indicates that the Plat of Beclan Place will be required to provide Flow Control to the Level 2 Flow Control levels and basic water quality as promulgated in the 2005 King County Surface Water Design Manual(KCSWDM) The conceptual storm drainage plan will include recharge of the existing Wetland A. The roof storm drains and pervious lawn surfaces from Lots 29 and 31 will be directed to discharge to the wetland buffer in Tract B. (See separate document, Wetland Hydrology Recharge Report for Wetland A). All of the other storm water runoff from the project will be collected and conveyed to the detention/water quality facility, including the minor street infrastructure widening and installation of concrete curb, gutter and sidewalk on Jericho Ave NE ROW. The roof drains from Lots 1 - 4 will be conveyed to the rear of the lots,then south to a catch basin in the NE 2nd Street right-of-way. A 10 foot wide storm drainage easement along the rear of Lots 1, 2 and 3 will allow access for this line. The controlled discharge from the detention vault in Tract A will be conveyed offsite to a Type 2 catch basin being installed by Shy Creek at the southeast intersection of Hoquiam and NE 2nd. Beclan Place has provided construction funds to Shy Creek to lower their proposed public storm drainage conveyance line in Hoquiam Ave NE to accommodate the proposed depth of our discharge pipe from the underground detention and water quality facility at the NE quadrant of the intersection. Attenuated flows from flow control facility will be conveyed southward down the newly installed public storm drainage conveyance system in Hoquiam Ave NE towards Maplewood Creek. The project proposed existing project drainage basin(PREDEV)includes 7.25 acres of existing area with a forested till existing land use covering. The existing house to remain on Lot 21 and its associated impervious driveway were not considered in the pre-developed basin. The proposed developed basin(DEV)is a 7.25 acre basin that is comprised of 3.93 acres of impervious area and 3.32 acres of lawn. The percentage of impervious surface per lot is 55%per the zoning and we will be reducing that to 50% of the lot area for the purposes of the flow control hydraulic calculations. The developed basin also contains the two concrete driveways for Lots 29 & 31 that drain to the private access drive. The KCRTS hydrologic modeling software that the 2005 KCSWDM requires engineers to utilize in sizing of flow control facilities (detention facilities) will be used to determine the project detention requirements. The City of Renton has adopted the 2005 KCSWDM as the City's storm drainage manual. 16 12183 TIR MA 120819.doc The KCRTS modeling program indicates that for Level 2 Flow Control standards the project will require 88,748 cubic feet of storage at peak reservoir stage of 7.65 feet above outlet(398.95)or elevation 406.60. The proposed flow control facility will be located in a separate detention tract at the south west corner of the project. The facility is proposed to be an underground detention/water quality wet vault with dimension configurations that are set to maximize site usage and the detention and water quality design requirements of the KCSWDM with respect to the available tract area set aside. The interior dimensions of the vault design provide approximately 11,601 square feet vault area The permanent water quality volume for the wet vault is calculated with respect to Section 6.4.1.1 of the 2005 KCSWDM for the Basic wetpond criteria. Wetpool volume=Vb=f*(0.9A; +0.25Atg+0.10Atf+0.10Ao)*(R) Where, Vb=wetpool volume (cf) f=volume factor A; =area of impervious surface (sf) Atg=area of till soil covered with grass (sf) Atf=area of till soil covered with forest(sf) Aa=area of outwash soil covered with grass or forest(sf) R =rainfall from mean annual storm event(inches) (refer to attached Figure 6.4.1.A KCSWDM) Therefore, Vb=3[(0.9(118,106)+0.25(118,106))*(0.47)] Vb=15,959 cf Required Vb Provided = 16,099 cf The proposed detention/water quality vault was modeled with the following dimensions, 112.06'(L)x 105'(W)x±11'(D). The water quality volume in Cell 1 is designed at 5.10 feet deep. At a depth of 5.10 feet the water quality cell will encompass approximately 27.2% of the vault bottom. The remainder of the vault, Cell 2 will be designed to drain to the outlet control structure in the southeast corner and have no water quality wetpool storage incorporated. The discharge from the facility would be to the newly installed Type 2 CB just to the south of the southeast corner of the detention wet vault, adjacent to the NE 2nd Street ROW. 17 12183 TIR_MA_120819.doc TIR Section 5—Conveyance System Analysis and Design The project proposes to install a series of Type I catch basins with Flow Thru frame and grates along the proposed internal public road,NE 2"d Place,that drain to a sag low point adjacent to Lots 13 and 25 and be picked up in the proposed public SD conveyance system. The flows will then be conveyed westward in the NE 2nd Place public ROW conveyance system, south down the Hoquiam Ave. public ROW to the open public detention/water quality wetpond at the Southwest corner of the project. There is also a 12"0 storm drainage conveyance pipe that runs along the property line between Lots 23 &24 that extends to the north parcel boundary for future connection of the under developed parcel adjacent to our parcel to the north. The flows through this proposed pipe are assumed be downstream of a future flow control facility and thus have been assumed as attenuated developed flows.. The project will install storm drainage improvements for the street widening and curb, gutter and sidewalk. The NE 2nd Street conveyance system will also convey the roof drain storm drainage runoff from the homes fronting on NE 2nd Street right-of-way's. The proposed lots fronting on the Hoquiam Ave. NE ROW will be conveyed in the private roof drainage system to the 1213 public storm drainage conveyance system within the Hoquiam Ave NE ROW. All public storm drainage pipe was preliminarily proposed to be a minimum of a 12"0 conveyance pipe. Upon conducting the Backwater Analysis utilizing the StormShed 2G hydraulic modeling software it was determined that of the proposed conveyance pipe in the system shall be 12"0 pipe. As a result of the first set of comments from the City of Renton the minimal street widening and addition of concrete curb gutter and sidewalk have been conveyed to the proposed public conveyance system in NE 2nd Street. In review of the previous backwater analysis it is our professional opinion that there is sufficient capacity in the NE 2nd Street conveyance line as designed to handle the additional Jericho Ave SE runoff flows at the KCSWDM design flows. Therefore we did not re run the StormShed 2G Conveyance calculations and have included the original December 2007 conveyance calculations. The wetland recharge flows from the two proposed structures will be discharge to two separate in ground bubble up dispersion trenches to be located at the outer edge of the Wetland A buffer(Tract B) in locations designed to disperse the clean stormwater runoff throughout the wetland buffer and Wetland A. Special Requirements Analysis The Special Requirements#1 -#5, of Section 1.3 of the 2005 KCSWDM do not apply to the project. 18 12183_T1R_MA 120819.doc Summary In summary,the project proposes Minor Amendment revisions to replace the approved underground concrete detention and water quality vault with an enlarged open detention/wetpond flow control facility to the R-5 zoning impervious coverage criteria of 55%impervious lot coverage to address the Level 2 Flow Control detention requirements. The project has implemented individual single-family lot Stormwater BMP's, Limited Infiltration for 10%of the total lot impervious area. These BMP's can be revised by the Developer/Contractor at the time of application of building permit and replace with an equivalent BMP. The flow control facility will be located in a separate detention tract, Tract A, at the northeast quadrant of the intersection of Hoquiam Ave.NE and NE 2nd Street. The flow control facility will be designed with the appropriate water quality dead storage to provide Basic Treatment. The project also performed a downstream analysis Core Requirement#2,to support our projects storm drainage design and found that the downstream appears to have sufficient capacity to convey the design storm event. Our proposed Minor Amendment revisions will be providing excess live storage volume to the redesigned open detention/wetpond and will not increase the discharges to the existing downstream conveyance system. The adopted and vested City of Renton storm drainage manual,the 2005 King County Surface Water Design Manual criteria requires that the project prepare a Full Drainage Review. 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King County Department of Development and Environmental Services TECHNICAL INFORMATION REPORT (TIR) WORKSHEET • ,J, NoR. km,s-Kzikkk.a'. /6//2- Part 1 PROJECT OWNER AND Part 2 PROJECT LOCATION AND PROJECT ENGINEER DESCRIPTION Project Ownar Project Name Arldrocc Location ),6 7 C ,: 1 i6 U�� _ ,rte Township 2?" 7 Phope 5_ (255) : P6-7;c4--7 Range Project Engineer Section P zi+r-A, SC1-1t s4l!t—y ps Company ` "!.,.vJ; vl- ,4 ct (- ;e-% Address/Phone TT-e6.17# 45 ( .5-6 72-4457 Part 3 TYPE OF PERMIT Part 4 OTHER REVIEWS AND PERMITS APPLICATION Subdivison ❑ DFW HPA ❑ Shoreline Management ❑ Short Subdivision E COE 404 ❑ Rockery ❑ Grading LI DOE Dam Safety ❑ Structural Vaults ❑ Commercial ❑ FEMA Floodplain g Other ❑ Other ❑ COE Wetlands 1 LpiNr t�iriewt.cT" Part 5 SITE COMMUNITY AND DRAINAGE BASIN Community N 7,J.3r G9 3TZ-LS Drainage Basin �+ R-(P t—l ill.r. _ 1— ,14'6 3!T<�?� 1 ,-)c.,.371?_ (,...,. { i�. •t��ER Part 6 SITE CHARACTERISTICS River Floodplain X' Wetlands Li Stream Li Seeps/Springs J Critical Stream Reach High Groundwater Table Depressions/Swales Groundwater Recharge r-1. !J Lake Other ❑ Steep Slopes Part 7 SOILS Soil Type Slopes Erosion Potential Erosive Velcoties A� Ci �TUre:et-ic ) s',rlcf-iTr 11%( Al!Nti A/... E' Additional Sheets Attached Part 8 DEVELOPMENT LIMITATIONS REFERENCE LIMITATION/SITE CONSTRAINT Ch. 4—Downstream Analysis ❑ Additional Sheets Attached Part 9 ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION AFTER CONSTRUCTION g Sedimentation Facilities V Stabilize Exposed Surface Stabilized Construction Entrance Remove and Restore Temporary ESC Facilities Perimeter Runoff Control Clean and Remove All Silt and Debris X Clearing and Graing Restrictions Ensure Operation of Permanent Facilities X Cover Practices ) Flag Limits of SAO and open space Construction Sequence preservation areas ❑ Other L Other Part 10 SURFACE WATER SYSTEM ❑ Grass Lined E Tank Infiltration Method of A aaysj� Channel. .: r(t .) ) Vault i Depression Pipe System Compensation/Mitigati L; Energy Dissapator L! Flow Dispersal on of Eliminated Site Li Open Channel X Wetland ii Waiver Storage ❑ Dry Pond Li Stream ❑ Regional Wet Pond Detention Brief Description of System Operation CPSNI CaN7T o C7-o k S rA ) nv►C.- \4Q Facility Related Site Limitations Reference Facility Limitation . Part 11 STRUCTURAL ANALYSIS Part 12 EASEMENTS/TRACTS • Cast in Place Vault IK Drainage Easement Retaining Wall Access Easement . ❑ Rockery > 4' High IS Native Growth Protection Easement ❑ Structural on Steep Slope X. Tract 'j itrtt' /1;;'e,1"-•�+7O t� ❑ Other ❑ Other Part 13 SIGNATURE OF PROFESSIONAL ENGINEER I or a civil engineer under my supervision my supervision have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attachments. To the best of my knowledge the information provided here is accurate. Z Signed/Da e KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL STORMWATER FACILITY SUMMARY SHEET f Development BiECL,A}.1 Date qi3/ !�7 N) Noe. MoDl,Pth-T16% Location Z55 12fcg4 /)-v \IE 1Zp r.st?,7A 114-A 9` O G`7 T Z3m1 R5 SSG i ENGINEER DEVELOPER Name 132A- rri\-,c..- ci-ko Name SAP Y V ATS"t3 Firm L5cH A-s5 ,tT-s i�..t< Firm Oc xk'Glf�NA1' Address V 4- s ,sr` View- Address 1¢7Z5 P /06 �E1�—ate g � 7 LI� �� qo6 Phone 0153) `�2G :49 Phone LZ, 6,O= 20¢-7 Developed Site: Acres 7, Zj Number of lots 3t Number of detention facilities on site: Number of infiltration facilities on site: .5 ponds S� ponds vaults vaults J tanks tanks Flow contol prov' ed in regional facility (give location) NI No flow control required Lev et_z_. Exemption number L'cr,31) g_ - Downstream Drainage Basins Immediate Major Basin Basin A Lc oErz. ted 1-1::\i-t6S1-41..04.16;r0 Basin B Basin C Basin D Number&type of water quality facilities on site: biofiltration swale (regular/wet/or sand filter(basic or large?) continuous inflow?) sand filter, linear(basic or large?) combined detention/WQ pond f sand filter vault(basic or large?) (WQortio basic •r large?) combined detention/wetvault stormwater wetland el compost filter 4, wetpond (p e r large?) i� filter strip Zj wetvault i. flow dispersion 10 farm management plan 96 landscape management plan 75 oil/water separator(baffle or coalescing plate?) 1998 Surface Water Design Manual 9/1/98 1 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL ' catch basin inserts: Manufacturer Al/A pre-settling pond in _A)/ pre-settling structure: Manufacturer A No flow-splitter catchbasin DESIGN INFORMATION INDIVIDUAL BASIN A%'` 'Jiff:, B C D Water Quality design flow Water Quality treated volume or r wetpond Vr 7 J 7/6 4 v no-t\I641l, l Vi, 9/1/98 1998 Surface Water Design Manual 7 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL DESIGN TOTAL INDIVIDUAL BASIN INFORMATION, cont'd 2s-I oikk.m-Tutri..yro Drainage basin(s) A B C D Onsite area �1 ;� 67g1,r 35,3'1�l Offsite area S r 37 8F 0.137 sr 4717 sc Type of Storage UNbm +NV Facility p-u_t,-r Rzoltruit, Live Storage Volume Vj_.5g 1 ô5 jR ?I /1/41('/4- eE4s1u-tegZ 86/2 9 Predeveloped Runoff 2-year Rate Oi I77 Fa ll7�a-s 10-year _ �#-5 O 3c 100-year 0,67 1cFc o,67,s F6 Developed runoff rate 2-year )24-=-F-1-.7 Ur 117-mss 10-year 177 c.r O, I�J 100-year L2 Type of restrictor Size of No. 1 orifice/restriction I ZZ" 74/A ©etpi C6 No. 2 I c 371 rrGE No. 3 I, u grek." ,7,0 (0,64 No. 4 (;►3.4 L S-tig6s ( i7 FLOW CONTROL & WATER QUALITY FACILITY SUMMARY SHEET SKETCH All detention, infiltration and water quality facilities must include a sketch per the following criteria: 1. Heading for the drawings should be located at the top of the sketch (top right-hand corner). The heading should contain: • North arrow(point up or to left) • D9# • Plat name or short plat number • Address (nearest) • Date drawn(or updated) • Thomas Brothers page, grid number 2. Label CBs and MHs with the plan and profile designation. Label the control structure in writing or abbreviate with C.S. Indicate which structures provide spill control. 3. Pipes-- indicate: Pipe size Pipe length Flow direction Use s single heavyweight line 4. Tanks--use a double, heavyweight line and indicate size (diameter) 5. Access roads • Outline the limits of the road • Fill the outline with dots if the road is gravel. Label in writing if another surface. 6. Other Standard Symbols: 1998 Surface Water Design Manual 9/1/98 1 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL • Bollards: • • • • ■ ■ ■ ■ • Rip rap 000000 000000 • Fences --x---x---x---x---x---x--- • Ditches ^'D—C D—C D--C D 7. Label trash racks in writing. 8. Label all streets with the actual street sign designation. If you don't know the actual street name, consult the plat map. 9. Include easements and lot lines or tract limits when possible. 10. Arrange all the labeling or writing to read from left to right or from bottom to top with reference to a properly oriented heading. 11. Indicate driveways or features that may impact access,maintenance or replacement. 9/1/98 1998 Surface Water Design Manual a BECLAN PLACE � A PORTION OF THE NW �4 OF THE NE �4 OF SEC. 15, TWP. 23N., RGE. 5E., W.M. _ CITY OF RENTON, KING COUNTY, WASHINGTON � � � ,�5_`� r{ '�� y`` ...� .� �. - °, � b � I, s�s� � • �+.r" VE7LAND E]USIING BASIN I DEVELCPm NE'LAND � � � �... �L�,� -��, 0.92 A 5 . �,°-, RECHARGE BASN � ��i � � / / �� . P I+ .' O.J9 ACRES � i � I a /�i � �� V� � �� ond"A"l� I � ,� � � � � i �hcOrt. 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Area- ._.-__.... Till Forest 7.25 acres!. Till Pasture 0.00 acres. Till Grass 0.00 acres Outwash Forest 0.00 acres Outwash Pasture 0.00 acres Outwash Grass 0.00 acres Wetland 0.00 acres Impervious 0.00 acres Total 7.25 acres Scale Factor : 1.00 Hourly Reduced Time Series: PREDEV1 >>1 Compute Time Series i Modify User Input 1 File for computed Time Series [.TSF] -2- G:\Land Projects 2004\12183\Storm\12I83_BMP\PREDEV_BMPI.doc �Hel�!FieS ,KCTS �ta�,t...�t°a:',° a" �'; •., a t�+.,e �54i'+"�:a�._ra,..,s;. .��;5 d. :.�a�'1.il..,r<<, .3an. a w &±*+a•�•. Flow Frequency Analysis Time Series File:predeo.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0 . 457 2 2/09/01 18 : 00 0.585 1 100 . 00 0 . 990 0 . 124 7 1/06/02 3 : 00 0. 457 2 25 . 00 0 . 960 0 . 339 4 2/28/03 3 : 00 0. 351 3 10 . 00 0 .900 0 . 012 8 3/24/04 20 : 00 0. 339 4 5 . 00 0 . 800 0 . 201 6 1/05/05 8 : 00 0. 296 5 3 . 00 0 . 667 0 . 351 3 1/18/06 21 : 00 0. 201 6 2 . 00 0 .500 0 . 296 5 11/24/06 4 : 00 0. 124 7 1 . 30 0 .231 0.585 1 1/09/08 9 :00 0. 012 8 1 . 10 0 .091 1Computed Peaks 0 . 542 50 . 00 0.980 -3- G:\Land Projects 2004\12183\Storm\12183_BMP\PREDEV_BMPl.doc BECLAN PLACE - MINOR AMENDMENT SA JOB #12183 DEVELOPED BASIN - DEV seer � � � �,� � , �-:. � R.� �i :.P F d, b�4LA ...._ .. .. ...a .. .. _ Land Use Type ?a Area [acres) Till Forest 0.000 Till Pasture 0.000 Till Grass 3.20 Outwash Forest 0.000 Outwash Pasture 0.000 Outwash Grass 0.000 Wetland 0.000 Impervious 4.051 Scale Factor 1.000 Time Step '4" Hourly C 15-minute J Data Type...._ • Reduced C Historic Compute Total Area . j Enter area for this land use type, 0.0 if NONE -1- G:Land Projects 2004\12183\Storm\12183 BMP\DEV_BMP1.doc 174) Land Use Summary I Area_.._w_ ? Till Forest; 0.00 acres' Till Pasture; 0.00 acres',: Till Grass! 3.20 acres Outwash Forest; 0.00 acres 1 f Outwash Pasture=. 0.00 acres Outwash Grass; 0.00 acres Wetland; 0.00 acres Impervious; 4.05 acres Total 7.25 acres' Scale Factor : 1.00 Hourly Reduced Time Series: DEVI Compute Time Series Modify User Input File for computed Time Series [.TSF] -2- G:\Land Projects 2004\12183\Storm\12183 BMP\DEV_BMP1.doc Iv ! Files , . - tas. ,.... ic. . cw:�,ar-,w ..a:.w.Kurz v.:nvaaawa..: rora*a'� -`a Time Series File:dev. tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 1 . 27 6 2/09/01 2 : 00 2 . 59 1 100 . 00 0 . 990 1 . 01 8 1/05/02 16 : 00 1 . 55 2 25 . 00 0 . 960 1 . 53 3 2/27/03 7 : 00 1 . 53 3 10 . 00 0 . 900 1 . 07 7 8/26/04 2 : 00 1 . 34 4 5 . 00 0 . 800 1 . 29 5 10/28/04 16 : 00 1 . 29 5 3 . 00 0 . 667 1 . 34 4 1/18/06 16 : 00 1 . 27 6 2 . 00 0 . 500 1 . 55 2 10/26/06 0 : 00 1 . 07 7 1 . 30 0 . 231 2 . 59 1 1/09/08 6 : 00 1 . 01 8 1 . 10 0 . 091 ;Computed Peaks 2 . 24 50 . 00 0 . 980 -3- G:\Land Projects 2004\12183\Storm\12183_BMP\DEV_BMPl.doc BE CLAN PLACE SA JOB #12183 Retention/Detention Facility POND BMP1 Type of Facility: Detention Pond Side Slope: 2.00 H:1V Pond Bottom Length: 89.00 ft Pond Bottom Width: 89.00 ft Pond Bottom Area: 7921. sq. ft Top Area at 1 ft. FB: 14933. sq. ft 0.343 acres Effective Storage Depth: 7.30 ft Stage 0 Elevation: 0.00 ft Storage Volume: 78869.cu. ft 1.811 ac-ft Riser Head: 7.30 ft Riser Diameter: 18.00 inches Number of orifices: 3 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 1.28 0.120 2 4.81 2.15 0.198 6.0 3 5.40 1.10 0.045 4.0 Top Notch Weir: Rectangular Length: 1.15 in Weir Height: 6.60 ft Outflow Rating Curve: None Stage Elevation Storage Discharge Percolation Surf Area (ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs) (sq. ft) 0.00 0.00 0. 0.000 0.000 0.00 7921. 0.01 0.01 79. 0.002 0.005 0.00 7928. 0.03 0.03 238. 0.005 0.007 0.00 7942. 0.04 0.04 317. 0.007 0.009 0.00 7950. 0.05 0.05 397. 0.009 0.010 0.00 7957. 0.07 0.07 556. 0.013 0.011 0.00 7971. 0.08 0.08 636. 0.015 0.013 0.00 7978. 0.09 0.09 716. 0.016 0.014 0.00 7985. 0.11 0.11 876. 0.020 0.015 0.00 8000. 0.28 0.28 2246. 0.052 0.023 0.00 8122. 0.45 0.45 3637. 0.083 0.030 0.00 8245. 0. 62 0. 62 5049. 0. 116 0.035 0.00 8369. 0.79 0.79 6482. 0. 149 0.039 0.00 8493. 0.96 0.96 7937 . 0.182 0.043 0.00 8619. 1.13 1.13 9413. 0.216 0.047 0.00 8746. 1.30 1.30 10911. 0.250 0.051 0.00 8874. 1.46 1.46 12340. 0.283 0.054 0.00 8995. 1.63 1. 63 13880. 0.319 0.057 0.00 9124. 1.80 1.80 15442. 0.355 0.060 0.00 9254. 1. 97 1.97 17027 . 0.391 0.062 0.00 9386. 2.14 2.14 18634 . 0.428 0.065 0.00 9518. 2.31 2.31 20263. 0.465 0.068 0.00 9651. 2.48 2. 48 21915. 0.503 0.070 0.00 9785. 2. 65 2. 65 23590. 0.542 0.072 0.00 9920. 2.82 2.82 25288. 0.581 0.075 0.00 10056. 2.99 2.99 27009. 0.620 0.077 0.00 10193. 3. 16 3. 16 28754 . 0. 660 0.079 0.00 10331. 3.33 3.33 30522. 0.701 0.081 0.00 10469. 3.50 3.50 32313. 0.742 0.083 0.00 10609. 3. 67 3. 67 34129. 0.783 0.085 0.00 10750. 3.84 3.84 35968. 0.826 0.087 0.00 10891. 4.01 4 .01 37832. 0.868 0.089 0.00 11033. 4.18 4 . 18 39719. 0. 912 0.091 0.00 11177. 4 .35 4 .35 41632. 0.956 0.093 0.00 11321. 4 .52 4 .52 43569. 1.000 0.094 0.00 11466. 4. 69 4 . 69 45530. 1.045 0.096 0.00 11612. 4.81 4 .81 46930. 1.077 0.097 0.00 11716. 4 .83 4 .83 47164 . 1.083 0.099 0.00 11733. 4 .85 4 .85 47399. 1.088 0. 103 0.00 11751. 4.88 4 .88 47752. 1.096 0.109 0.00 11777. 4.90 4 . 90 47988. 1.102 0.117 0.00 11794. 4.92 4. 92 48224. 1.107 0. 128 0.00 11811. 4.94 4. 94 48460. 1.112 0.140 0.00 11829. 4.97 4 . 97 48816. 1.121 0.149 0.00 11855. 4. 99 4 . 99 49053. 1. 126 0. 152 0.00 11872. 5.01 5.01 49291. 1.132 0. 156 0.00 11890. 5.18 5.18 51324 . 1.178 0.178 0.00 12038. 5.35 5.35 53384 . 1.226 0.195 0.00 12188. 5.40 5.40 53994 . 1.240 0.200 0.00 12232. 5.41 5.41 54117. 1.242 0.201 0.00 12241. 5.42 5.42 54239. 1.245 0.203 0.00 12250. 5.43 5.43 54362. 1.248 0.205 0.00 12259. 5.45 5. 45 54607. 1.254 0.208 0.00 12277. 5.46 5. 46 54730. 1.256 0.211 0. 00 12286. 5.47 5.47 54853. 1.259 0.214 0.00 12294 . 5.48 5.48 54976. 1.262 0.216 0.00 12303. 5.49 5.49 55099. 1.265 0.218 0.00 12312. 5.66 5. 66 57205. 1.313 0.238 0.00 12463. 5.83 5.83 59336. 1.362 0.256 0.00 12616. 6.00 6.00 61494. 1.412 0.271 0.00 12769. 6.17 6. 17 63678. 1.462 0.285 0.00 12923. 6.34 6.34 65888. 1.513 0.299 0.00 13078. 6.51 6.51 68124 . 1.564 0.311 0.00 13234. 6.60 6. 60 69319. 1.591 0.318 0.00 13317. 6.69 6. 69 70522. 1. 619 0.331 0.00 13400. 6.78 6.78 71731. 1.647 0.345 0.00 13484. 6.86 6.86 72813. 1.672 0.361 0.00 13558. 6.95 6. 95 74037. 1.700 0.381 0.00 13642. 7.04 7.04 75269. 1.728 0.402 0.00 13726. 7.13 7. 13 76508. 1.756 0.425 0.00 13811. 7.21 7.21 77616. 1.782 0.449 0.00 13886. 7.30 7.30 78869. 1.811 0.475 0.00 13971. 7.40 7.40 80271. 1.843 0. 943 0.00 14066. 7.50 7.50 81683. 1.875 1.790 0.00 14161. 7.60 7. 60 83103. 1.908 2.890 0.00 14256. 7.70 7.70 84534 . 1.941 4 .190 0.00 14352. 7.80 7.80 85974 . 1.974 5.670 0.00 14448. 7.90 7. 90 87423. 2.007 7. 100 0.00 14544 . 8.00 8.00 88883. 2.040 7. 630 0.00 14641. 8.10 8.10 90352. 2.074 8. 130 0.00 14738. 8.20 8.20 91830. 2.108 8. 600 0.00 14835. 8.30 8.30 93319. 2. 142 9.040 0.00 14933. 8.40 8.40 94817. 2.177 9.460 0.00 15031. 8.50 8.50 96325. 2.211 9.860 0.00 15129. 8. 60 8. 60 97843. 2.246 10.250 0.00 15228. 8.70 8.70 99370. 2.281 10.620 0.00 15326. 8.80 8.80 100908 . 2.317 10. 980 0.00 15426. 8. 90 8. 90 102455. 2.352 11.320 0.00 15525. 9.00 9.00 104013. 2.388 11. 660 0.00 15625. 9.10 9.10 105581. 2.424 11. 990 0.00 15725. 9.20 9.20 107158. 2.460 12.300 0.00 15826. Hyd Inflow Outflow Peak Storage Target Calc Stage Elev (Cu-Ft) (Ac-Ft) 1 2.59 ******* 1.72 7.49 7.49 81559. 1.872 2 1.27 0.46 0.46 7.25 7 .25 78150. 1.794 3 1.53 ******* 0.31 6.44 6.44 67197. 1.543 4 1.27 ******* 0.31 6.51 6.51 68156. 1.565 5 1.34 ******* 0.23 5. 61 5. 61 56636. 1.300 6 0.79 ******* 0. 15 4 .99 4 . 99 49100. 1. 127 7 1.01 ******* 0.09 4 .50 4 .50 43316. 0. 994 8 1.07 ******* 0.08 3.16 3. 16 28713. 0. 659 Route Time Series through Facility Inflow Time Series File:dev.tsf Outflow Time Series File:rdout Inflow/Outflow Analysis Peak Inflow Discharge: 2.59 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: 1.72 CFS at 10:00 on Jan 9 in Year 8 Peak Reservoir Stage: 7.49 Ft Peak Reservoir Elev: 7.49 Ft Peak Reservoir Storage: 81559. Cu-Ft 1.872 Ac-Ft Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS % % % 0.007 32703 53.332 53.332 46. 668 0. 467E+00 0.020 6792 11.076 64 .408 35.592 0.356E+00 0.033 5776 9.419 73.827 26. 173 0.262E+00 0.047 5308 8. 656 82.484 17.516 0. 175E+00 0.060 4417 7.203 89. 687 10.313 0. 103E+00 0.073 2610 4 .256 93. 943 6.057 0. 606E-01 0.086 1886 3.076 97.019 2. 981 0.298E-01 0. 100 1334 2. 175 99.194 0.806 0.806E-02 0. 113 70 0. 114 99.309 0. 691 0.691E-02 0. 126 31 0.051 99.359 0. 641 0. 641E-02 0.139 18 0.029 99.388 0. 612 0.612E-02 0.153 33 0.054 99.442 0.558 0.558E-02 0.166 46 0.075 99.517 0.483 0.483E-02 0.179 40 0.065 99.583 0.417 0.417E-02 0.192 48 0.078 99. 661 0.339 0.339E-02 0.206 26 0.042 99.703 0.297 0.297E-02 0.219 11 0.018 99.721 0.279 0.279E-02 0.232 30 0.049 99.770 0.230 0.230E-02 0.245 24 0.039 99.809 0. 191 0.191E-02 0.259 18 0.029 99.839 0. 161 0.161E-02 0.272 15 0.024 99. 863 0.137 0.137E-02 0.285 14 0.023 99.886 0.114 0.114E-02 0.298 15 0.024 99. 910 0.090 0.897E-03 0.312 24 0.039 99. 949 0.051 0.506E-03 0.325 9 0.015 99.964 0.036 0.359E-03 0.338 5 0.008 99.972 0.028 0.277E-03 0.351 1 0.002 99.974 0.026 0.261E-03 0.365 2 0.003 99. 977 0.023 0.228E-03 0.378 2 0.003 99. 980 0.020 0. 196E-03 0.391 2 0.003 99. 984 0.016 0. 163E-03 0.405 1 0.002 99. 985 0.015 0.147E-03 0.418 2 0.003 99. 989 0.011 0. 114E-03 0.431 2 0.003 99. 992 0.008 0.815E-04 0.444 1 0.002 99. 993 0.007 0. 652E-04 0.458 1 0.002 99. 995 0.005 0.489E-04 0.471 2 0.003 99. 998 0.002 0. 163E-04 Duration Comparison Anaylsis Base File: predev.tsf New File: rdout.tsf Cutoff Units: Discharge in CFS Fraction of Time Check of Tolerance Cutoff Base New %Change Probability Base New %Change 0.100 I 0. 95E-02 0.80E-02 -16.3 I 0. 95E-02 0. 100 0.097 -3.8 0. 128 I 0. 63E-02 0. 64E-02 0.8 I 0. 63E-02 0.128 0. 131 2.7 0.155 I 0.49E-02 0.54E-02 10. 6 I 0.49E-02 0. 155 0. 164 5.5 0.183 I 0.37E-02 0.39E-02 6.2 I 0.37E-02 0.183 0. 186 1. 6 0.210 I 0.28E-02 0.29E-02 1.7 I 0.28E-02 0.210 0.216 2. 9 0.238 I 0.22E-02 0.21E-02 -5.1 I 0.22E-02 0.238 0.233 -1. 9 0.265 I 0. 15E-02 0. 15E-02 2.2 I 0. 15E-02 0.265 0.268 1.3 0.292 I 0. 10E-02 0. 98E-03 -3.2 I 0. 10E-02 0.292 0.292 -0.3 0.320 I 0. 62E-03 0.42E-03 -31.6 I 0.62E-03 0.320 0.309 -3.4 0.347 I 0. 34E-03 0.26E-03 -23.8 I 0.34E-03 0.347 0.330 -4. 9 0.375 I 0.21E-03 0.21E-03 0.0 I 0.21E-03 0.375 0.377 0.5 0.402 I 0. 16E-03 0. 15E-03 -10.0 I 0.16E-03 0.402 0.401 -0.4 0.430 I 0. 98E-04 0. 98E-04 0.0 I 0. 98E-04 0.430 0.430 0.0 0.457 I 0. 16E-04 0.49E-04 200.0 I 0. 16E-04 0.457 0.472 3.2 Maximum positive excursion = 0.013 cfs ( 9.9%) occurring at 0. 133 cfs on the Base Data:predev.tsf and at 0.146 cfs on the New Data:rdout.tsf Maximum negative excursion = 0.010 cfs ( -8.8%) occurring at 0. 108 cfs on the Base Data:predev.tsf and at 0.099 cfs on the New Data:rdout.tsf Attachment A Beclan Place - Minor Amendment Open Pond Volumes LIVE Storage Required Vol Stage Area Avg VOL Cum VOL 78,869.00 cf 406.30 14,494.6 406.00 14,217.5 4306.82 83076.17 404.00 12,498.5 26716.00 78769.35 402.00 10,802.6 23301.10 52053.35 Excess Volume Percentage of Required 400.00 9,169.6 19972.20 28752.25 4,207.17 cf 105.33% 399.00 8,390.5 8780.05 8780.05 0 0 83,076.17 Dead Storage-Total Facility Required Vol Stage Area Avg VOL Cum VOL 26,905.00 cf 399.00 8,390.5 398.00 7,600.6 7,995.55 35,997.35 396.00 5,468.5 13,069.10 28,001.80 Excess Volume Percentage of Required 394.00 3,764.4 9,232.90 14,932.70 9,092.35 cf 133.79% 392.00 1,935.4 5,699.80 5,699.80 35,997.35 Dead Storage-Cell 1 25%Required Vol Stage Area Avg VOL Cum VOL 8,999.34 cf 399.00 3205.6 398.00 2859.7 3,032.65 10,697.55 396.00 1871.7 4,731.40 7,664.90 Excess Volume Percentage of Required 394.00 1061.8 2,933.50 2,933.50 1,698.21 cf 118.87% 10,697.55 Actual Pectegage of Total Dead Storage 29.72% Attacment A G:\Land Projects 2004\12183\Storm\12183_MM_Pond_120809.xls Attachment B BECLAN PLACE MINOR AMENDMENT KCRTS POND DESIGN VOLUME Pyramidic Frustrum Formula 2:1 side slopes Volume= h/3 ( a +A+ (a x A) %2 ) square bottom only h = height(depth) Length Width A= area of base (bottom area 89.00 89.00 a= area of top (water surface @ h) A= L x W = 7,921 sf a = ((L+(h-x 4))2 = 13,971.24 sf h = 7.3000 ft Pond Volume= 78,869.30 sf Attacment B 12183 Stage Calc.xls Attachment C BECLAN PLACE - DETENTION BASIN CALCS 55% Impervious Coverage - Minus 10% BMP Reduction Detention Basin IMPERV PERV Total Lots 123,420 108,668 232,088 Pond - 20,628 20,628 Road Internal 48,977 1,933 50910 Driveways (29&30) 1,000 - 1000 Tract Access 3,219 - 3219 Offsite - 8,137 8137 Grand Totals 176,616 139,366 315,982 4.05 ac 3.20 ac 7.25 ac Attachment C 12183_Detention Area Calcs_BMP.xls Spillway calculations Pond Emergency Overflow Spillway For this weir Q = C 2g(2/3LH312+8/15zH5 2 (From KCSWDM 5.3.1.2) C = 0.6 discharge coefficient L = 6.00 ft (bottom width 6 feet min.) z = 3 Approximate slope h = 0.7 ft H = 0.4 ft (-0 .3' freeboard required at a min) Q = 5.65 cfs (100 Year Peak) V = 1.96 fps Filename 12183_GENERAL.XLS Tab KCSPILWY 8/17/2012 11:59 AM BECLAN PLACE WETLAND BASIN ANALYSIS W-EXST Event Summary Event Peak Q (cfs);Peak T (hrs);Hyd Vol (acft)1Area (ac)sMethod'�Raintype 2 year 0.1173 8.46 0.0652 1 0.9200 1 SCS -TYPE1A other 1 0.1307 8.46 r 0.0710 0.9200 ': SCS ITYPE1A 5 year . 0.3411 1 8.41 0.1611 0.9200 ± SCS ITYPE1A I •10 year 0.4226 8.41 0.1955 0.9200 SCS iTYPE1A.I 25 year 0.4640 8.41 0.2130 0.9200 SCS ITYPE1A 1100 year 1 0.6764 8.41 0.3029 0 9200 SCS ITYPE1A Record Id: W-EXST Design Method SCS ;Rainfall type TYPE1A Hyd Intv 10.00 min Peaking Factor 484.00 iAbstraction Coeff__u._._ 0.20 'Pervious Area 1 0.92 ac iDCIA 0.00 ac Pervious CN 86.00 DC CN 0.00 _-.._�_.._...__.._.-.._..._.......-_._..-.....-..._r..._..........._..,.-,_,......_.-.._.._._.._-.........-_..._._..-..,__,......._.__...,..,..._.._.__.............__...,_......_...,..____.«..r -...._._.-._:._,.._.._..mss 'Pervious TC 51.55 min DC TC 0.00 min it Pervious CN Calc IDescription SubArea 1 Sub cn Wood/forest land (young 2nd growth/brush) 0.81 ac j 86.00 1 Open spaces, lawns, parks (50-75% grass) 0.11 ac 86.00 Pervious Composited CN (AMC 2) 86.00 Pervious TC Calc Type j Description j Length !Slope j Coeff I Misc :� TT Sheet' g ; Woods or forest with light - .284 :246%10 4-___ . .4000, 2.50 [51.55 underbrush.: 0.40 .ft .00 t in imin Pervious TC 51.55 min WETLAND BASINS.doc Gz BECLAN PLACE WETLAND RECHARGE FLOW COMPARISION Existing Developed Existing Developed Existing Developed Existing Developed Peak Q Peak Q Peak T Peak T Hyd Vol Hyd Vol Area Event (cfs) (cfs) (hrs) (hrs) (acft) (acft) (ac) Area(ac) Method Raintype 2 year 0.1173 0.1235 8.46 8.04 0.0652 0.0419 0.92 0.39 SCS TYPEIA other 0.1307 0.1328 8.46 8.04 0.071 0.0448 0.92 0.39 SCS TYPEIA 5 year 0.3411 0.2655 8.41 8.02 0.1611 0.0879 0.92 0.39 SCS TYPEIA 10 year 0.4226 0.3131 8.41 8.02 0.1955 0.1037 0.92 0.39 SCS TYPEIA 25 year 0.464 0.3369 8.41 8.02 0.213 0.1116 0.92 0.39 SCS TYPEIA 100 year 0.6764 0.456 8.41 8.02 0.3029 0.1518 0.92 0.39 SCS TYPEIA The recharge analysis for the wetland attempts to provide equivalent flows for the most common event,the 2-year event. 2/22/2008 Wetland Rechrage Flow Comparision.xls FILE NAME:05057 CONVEY VA1945 South 375th Street Schweikl& Associates, llc Federal Way, WA 98003 p Phone: (253) 815-1700 Civil Engineering, Project Management Fax: (253) 815-1701 & Consulting BECLAN CONVEYANCE CALCULATIONS PIPES AND NODES --JILL, .14 CA Mw loot 04 w.c..V CI 05®: .;c a a:4.,; 'i ®him P NNv j :N® NO r Wpm, 1112 V .d...a. ..4 ",!1 NI i O 'N11 Nil N11 N1[ Ni? 2...;_eii- 'q 6.,a .,0,elI--.,e '"TAN 4 Nit `/ N N ..4 O f 'a I 0 Flt Ni 4 I 1i I '9 NS 1' NI N1 41 Ir'''r ...., .. .... ., .. ....dNi .. :,,.:mao._.fib... 1 FILE NAME:05057 CONVEY FLOWS AND HGL PtIM .1 l 5...... Q 11).+Cp..... ....... ........ .. _ .......... .:.......:._. ._....... ...:.. ..- ..... ........... 0 most .15.51)0 ti k roew.✓. 113.)05 0 � aQ,.m :,6 ,11a• 4550 N 1 515 131(4.113.0311 111.350 ft 113.151 11 111.1010 136.3510 .i6 NO dr. ,•6_.4.01.45._c9 JP.-t9 3441• 1lids da O.t✓Lns OldsH 1.1,511 11)1.1130 11.1110 1 .021 0 la I • I 1.11.• 1111.)1/ft 1.1/111 .o ;a45_.____.'__.._.ft-10 5.0 q• 0105 .0 • 414330 ` 2asd5 .. ',JT,'111■ 110.1150 113.1310 ^_..._.tO 1)Ida ...__.. •..4-____01)Oft . aI • I f CB RIMS AND PIPE LENGTHS s vr. ARMe Yck Loma 0.Mu M• 0'p own4 •• 119.1900 a meek lgwd:. ' ij 11).4.0 414'120 5 n.10 1113615 111.010 0 19.100111.9)05 121.5600 1 .1111 ti 9-{n105_.4_ALMA..Y-1'1.161,0 p1.f10 30. 1 M p • 11).959.1( /11).0600 110108 1.411f10 :O •.9 .0 514 5 9 .:6 . 1 12l J011 ]s.00 s I 41311 1}x,5115 1045 ft 11p.020 5 :0 411115 ]0. 0 ---- ----.a 0_ Il.)510 410100 1153110 -- +- .4._..._._......_115.5.x----_.....__C9._.r.__._.L1445 __....._....._.. g 2 FILE NAME:05057 CONVEY BASINS AND PIPE SLOPES aeow leen 'r slam a i i. eeu e.s�e e re5x WIN le,a Ie1% leen 6 ].ux nel% VP;ere VP; ,� ro,n.i l s.444 IRI eel redox lehl 9 R% _9_____._ Atm le le% len /,Be _f+ a ]KY O AI i BASIN RECORD Record Id: B3 Design Method Rational I IDF Table: I Seattle Composite C Calc Description [SubArea Sub c 'Pavement and roofs (n=0.90) [0.10 ac +0.90 Directly Connected TC Calc Type DescriptionLength r h SloPe , Coeff I Misc 1 TT i � Sheet Smooth Surfaces.: 0.011 '200.00 ft 136.00% X0.0110[2.50 in'0.75 min:: Channel (interm) !Concrete pipe (n=0.012) 11000.00 ft10.50% 10.01201 5.55 min 1► Directly Connected TC 6.30mm 3 FTTP NAME:05057_CONVEY Record Id: B4 Design Method 1 1 Rational 1 , IDF Table: I Seattle Composite C Calc ! 'Description 1SubArea Sub c [Lawn 0.52 ac 0.25 11---------------------6ii; ti on nectediC Calc------------ y r 1 Type I Description i Length ;Slope I Coeff 1 Misc TT r----aOrt prairie grass and lawns.: . Sheet 10 15 245.00 ft15.00% 0.150012.50 in 15.74 nun t • 1 i 'Shallow!Paved 11'7.00 ft 10.50%110.01001 10.25 min 1 Directly Connected TC 115.93min I Record Id: B5 r , , Design Method , Rational IDF Table: Seattle , 1 Composite C Calc IDescription SubArea Sub c !Lawn 0.39 ac 10.25 Pavement and roofs (n=0.90) 0.15 ac 10.90 , - Directly Connected TC Calc 1-- Type r Description 1 Length iSlope Coeff I Misc TT I !Sheet ! Short prairie grass and lawns.: I .168.00 ft15.00%!0.150012.50 in 11.64 min 1 - iShallow!Paved 120.00 fti0.50%[0.0100 i [0.29 min 11_ Directly Connected TC I- 11.87min 4 FILE NAME:05057 CONVEY Record Id: B6 yDesign Method Rational ` IDF Table: 1 Seattle Composite C Calc 1Description !SubArea [Sub c ;Pavement and roofs (n=0.90) 0.53 ac [0.90 [Lawn '0.36 ac ;0.25 , .- ...,..._._.........:..................__...._.:........... .:...._...:._..._..:;._... ,. ....E i I - Directly Connected TC Calc ;I I Type I Description j Length 'Slope 1 Coeff I Misc TT I Sheet r-h or t 0 15 prairie grass and lawns.: ;245.00 ft 15.00%;0.150012.50 in'i 15.74 mini. ' 1__ j , Shallow Paved —` 127.00 ft T0.50%10.01001 10.39 mut' I IDirectly Connected TC 16.05min 1 Record Id: B7 Design Method Rational ' IDF Table: I Seattle Composite C Calc (Description ISubArea ;Sub c Pavement and roofs (n=0.90) ;0.53 ac ;0.90 Lawn ;0.42 ac (0.25 I Directly Connected TC Calc Type Description Length �i t r I Sloe Coeff I Misc TT � Short prairie grass and lawns.: Sheet 0.15 240.00 ft 5.00o 10.150012.505in' 15.48 min Shallow Paved - 132.00 ft f0.50%'0.0100 J 11.93 mm Directly Connected IC17.01 mm 5 Fri P NAME:05057 CONVEY Record Id: B9 _ Design Method Rational IDF Table: Seattle —' — Composite C Calc 1Description 'SubArea jSub c ;Pavement and roofs (n=0.90) :0.13 ac ;0.90 ILawn ;0.08 ac .�..-- .......__.10. 25 ` Directly Connected TC Calc ......... . : Type 1 Description 1 Length Slope:I Coeff I Misc I TT —' Sheet Short prairie grass and lawns • 0.15 1133.00 ft 15.00% 10.1500 2.50 in[9.65 min' 1Shallow Paved 15.00 ft 10.50%10.01001 10.07 min' l Directly Connected TC [9.71 mm, Record Id: B10 1 Design Method Rational 1 IDF Table: j Seattle Composite C Calc jDescription ;SubArea Sub c Pavement and roofs (n=0.90) 0.29 ac 10. I Lawn 10.17 ac 0.25 I Directly Connected TC Calc I Type Description 1 Length ISlope rCoeff 1 Misc 1 TT , r !Short prairie grass and lawns.: 1�..._._ !Sheet +0.15 170.00 ft 5.00% 0.1500 2.50 in 11.75 min j I (Shallow!Paved 17.00 ft 10.50%10.01001 10.10 min li 3 Directly Connected TC .111.83min 6 FILE NAME:05057 CONVEY Record Id: B10A DesignMethod I Rational IDF Table Seattle rComposite C Calc 'Description ISubArea (Sub c [Pavement and roofs (n=0.90) :0.08 ac ;0.90 Lawn :0.04 ac :0.25 I Directly Connected TC Calc I Type Description Length Slope j Coeff j Misc f TT 'Sheet !Short prairie grass and lawns.: 0.15 20.00 ft 15.00% [0.150012.50 in{2.12 min _ _ ,.... _ ___ _ter_ 'Shallow _,'Paved ..100.00 ft 10.50% 10.0100 11.46 min Directly Connected TC 13.28min Record Id: BlOB I Design Method [ Rational ( IDF Table: I Seattle Composite C Calc !Description +SubArea ;Sub c I [Pavement and roofs (n=0.90) i0 06 ac ;0.90 Directly Connected TC Calc Type 1 Description j Length 1 Slope.!Coeff.1 Misc 1 TT 4!Sheet (-Short prairie grass and lawns 0.15 120.00 ft X5.00% 0.1500 ;0.00 in j0.00 min: 'Shallow Paved !100.00 ft-10.50% ;0.0100 , -[1.46 min ( Directly Connected TC 1-3.28min 7 FILE NAME:05057 CONVEY Record Id: B11 Design Method r -^Rational 1- IDF Table: 1 Seattle 1 Composite C Calc ff (Description ISubArea ;Sub c !Pavement and roofs (n=0.90) ;0.02 ac '0.90 'Lawn ;0.01 ac 10.25 Directly Connected TC Calc Type r Description -(Length Slope ` Coeff Misc TT Sheet 'Short prairie grass and lawns.: 0.15 0.01 ft 5.00% 10.1500 2.50 in 0.00 min.: 'Shallow Paved 150.00 ft '0.50% I0.0100 1 0.73 min 11 Directly Connected TC 10. 58min I Record Id: B12 Design Method Rational IDF Table: Seattle I Composite C Calc 'Description 1SubArea 'Sub c Pavement and roofs (n=0.90) 10.20 ac 10.90 1 Directly Connected TC Calc Type I Description ! Length Slope Coeff Misc TT Sheet 'Short prairie grass and lawns.: 0.15 '0.01 ft 15.00% 10.150012.50 in 0.00 min (Shallow rPaved _ - —�- 1360.00 ft 10.50% 10.0100 I ' 15.26 min Directly Connected TC r4.18rnin 8 FILE NAME: 05057 CONVEY Record Id: B12A Design Method 1 Rational E IDF Table: Seattle Composite C Calc tion Descri p lSubArea [Sub c !Pavement and roofs (n=0.90) !0.04 ac 10.90 Directly Connected TC Calc Type I Description Length (Slope Coeff ; Misc � TT (Sheet !Short prairie grass and lawns.: 0.15 10.01 ft —[5.00% :0,1500 0.00 m 10.00 min :Shallow !Paved 100,00 ft !0.50% ;0,0100 11.46 min: Directly Connected TC ! 1.16min Record Id: B13 Design Method r Rational 1 IDF Table I Seattle Composite C Calc Description irSubArea Sub c !LAWN 1 28 ac x _M[0.25 !Pavement and roofs (n=0.90) 0.30 ac E0.90 Directly Connected TC Calc Type Description 1 Length [Slope ! Coeff Misc TT • 1 Sheet !Short prairie grass and lawns.: 0.15 10.01 ft 15.00% 16.1500.10.00 m 10.00 min. Shallow [Paved 100.00 ft F6:50% 10.01001 [1.46 min 1 Directly Connected TC 1.16min• 9 FILE NAME:05057 CONVEY Record Id: B14 I Design Method 7 Rational I IDF Table: Seattle Composite C Calc 'Description iSubArea ;Sub c !Pavement and roofs (n=0.90) ;0.32 ac 10.90 Lawn 10.17 ac 10.25 f Directly Connected TC Calc F; Type Description F Length 'Slope 1 Coeff Misc 1 TT Sheet (Short prairie grass and lawns 0.15 ;125.00 ft 5.00% 10 1500 X2.50 m 19.19 min: Shallow!Paved 17.00 ft 10.50% 10.01001 '0. 10 min, ' Directly Connected TC _ ___ 9 1------7mun Record Id: B15 Design Method Rational IDF Table: i Seattle r Composite C Calc 3 !Description jSubArea 'Sub c avement and roofs (n=0.90) !0.40 ac ;0.90 !Lawn 16.10 ac 10.25 Directly Connected TC Calc Type Description r- : Length [Slope Coeff Misc '' TT Sheet 1Short prairie grass and lawns.: 0.15 120.00 ft 15.00%;'0.150012.50 in 2.12 nun:: Shallow.IPaved 1130 00 ft x0.50% 0.01001 11.90 min Directly Connected TC [3.63min 10 FILE NAME:05057 CONVEY Record Id: B16 1 •' Design Method Rational s IDF Table: 1 Seattle r Composite C Calc 'Description [SubArea •!Sub c (Pavement and roofs (n=0.90) .0.03 ac 10 .90 �~ 'Lawn 0.08 ac 10 .25 Directly Connected TC Calc 11 Type j DescriptionI Length i Slope Coeff 1 Misc 1 TT 1 r§heet 1-Short prairie grass and lawns.. 0.15-520.00 ft15.00% 0.1500 !2.50 m 18.89 min Shallow ;Paved 45.00 ft ,0.50 .0.0100 ; 10.22 min it /o r _.�. 1 Directly Connected TC 19.06mm Record Id: B17 Design Method Rational 1 IDF Table: 1 Seattle 'I j Composite C Calc :1 1-Description '1-SubArea ;Sub c jPavement and roofs (n=0.90) ,0.58 ac 10.90 jLawn 10.21 ac _ . X0.25 IF---- Directly Connected TC Calc i 1 Type Description ' Length i Slope 1 Coeff j Misc 1{ TT 1i YP � P gt � _ I 1 Short prairie grass and lawns.: 0 1 [ [ .Sheet ?0.15 '195.00 ft,5.00%10.150012.50/0 0.150012.50 m 113.11 min' 'Shallow!Paved 35.00 ft 16.50%101 10.51 min rDirectly Connected TC 113.52min ice._ 11 FILE NAME:05057 CONVEY Record Id: B18 Design Method 1 Rational IDF Table: 1 Seattle Composite C Calc Description SubArea Sub c !Pavement and roofs (n=0.90) 0.28 ac ;0.90 (Lawn 0.11 ac 0.25 1 Directly Connected TC Calc I Type 1 Description` ,p ' Length �Slope ; Coeff i Misc I TT I [Sheet Short prairie grass and lawns.: 0.15 {20.00 ftI 5.00% 10.1500 12.50 in .12m[2m Shallow Paved 1230.00 ft f 0.50% 10.01001 [3.36 min :I Directly Connected TC [4.79min Record Id: B21 Design Method Rational 1. IDF Table: Seattle 1 Composite C Calc Description 1SubArea Sub c [Pavement and roofs (n=0.90) !0.07 ac [0 .90 [Lawn !0.10 ac 10.25 — ;I Directly Connected TC Calc Type I Description 'Length !Slope rCoeff [Misc W;1 TT Sheet Short prairie grass and lawns.: 0.15 45.00 ft 15.00% [0 1500`2.50 m [4.06 mm Shallow [Paved [60.00 ft 10.50%10.0100' [6:88 min:: Directly Connected TC 1 4.75min 12 FILE NAME: 05057 CONVEY ROUTING DATA USING Seattle AND [25 yr] NOTZERO RELATIVE RATIONAL 'Reach. Area I TC Flow 1 Full Full 'nDe th nVel Wel CBasin 1 Q p ; ID (ac) min (cfs) (cfs) ratio (ft) Size ft/s) (ft/s) 1 /H d I P5 0.5400i12.6310.421113.6488 ' 0.12 1 0. 2290 Dl 1047 4.6457 : B5 ; P7 0.9500 117.37 10 .8706 [9.7199 0.09 0.2026 12" 1 7.6407 12.3758 B7 I � 1 i Diam 1 P6 11.8400 17.65 11.6993 10.4975 ? 0.16 10.272012" 9.8315 13.3658 B6 1 I ! i Diam 1 P4 12.9000 117.69 12.2161 121.7059 0.10 1 0.2153 iD. {17.8345 (27.6369: B4 P15 0.5000 4.14 :1.1141 3.7684 0.30 0.3726 1Dlam 14.1782 4.7981 I B15 , P18 10.7900 j 13.64 10.9727 1 3. 6488 ' 0.27 0.3530 Diam 3.9243 4.6457 B18 1 : .. P17 11.5800113.75 11.93561 8.5103 j 0.23 1 0.3247 . 8.7559 10.8356' B17 I I ( IDiam i ... ._ _ P16 11.6900' 13.92 12.0065 6.8262 0.29 0.3716 12" 7.5517 -1- 8.6914 B16 i ( i . I 1 _ P14 2.6800. 14.15 13.1858 13.6488 0.87 10.7231 ' D. 15.2380 4.6457 B14 P13 10.5800 ; 1.62 10.9839 1 6.6732 ! 0.15 r-0.2593 1 12 1 6.0874 8.4965 B13 I 4 j IDiam I ( P11 _10.61001 1.82 11.04321 7.0149 ! 0.15 ' 0.2603 I . 1 6.4204 8.9317 B11 IDiam I P21 13.3700114.24 13.8289110.2441-0.37 ID 1 0.4233 12iam. 12.1038 13.0432 B12A P12 13.5700 14.39 14.1116 111.9910 0.34 ! 0.4038 1 12" 113.8390 15.2675 1 B12 P02 0.0600 4.09 0.1563 1 4.1164 0.04 I0.1333 1 2.5111 5.2411 BlOB i._ _... _i. _. ; . (Dram If-- --__ ( 12" f- - P01 0.180014.69 10.3936. 5.2515 . 0.07 10.1851 Dim' 3.9339 6.6864 BIOA I i P10 10.6400112.05 10 .7988 7.5133 0.11 0.2202 Diam 1 6.2268 9.5662 B10 1 P9 l0.8500 112.28 41.0384 111.7920 10.09 1 0.2007 I 1 9.2409 15.0141 ( B9 1 Diam I 1 P8 14.4200 54.49 15.0331 113.6524 10.37 1 0.4204 112" 116.0571 (17.3828 { - I 13 FILE NAME:05057_CONVEY From To Itch Loss I App 1 Bendi-Junct Loss HW Loss I Max El -1 Node Node (ft) 1 (ft) (ft) . 1 (ft) Elev (ft) (ft) •I 1397.0162 N4 N3 , 403.6342 [1.5009 2.0073 1 0.2784 404.4189 :1412.7500 N5 N4 404.4330 ' 404.4330. 1406.4000 No approach losses at node N7 because inverts and/or crowns are offset. N6 N4 4:10.4146 410.4146 1 419.62001 N7 N6 413.0382 7 413.03827F-41675100 • N8 N3 405.2841 10.4256 10.0019 0.0803 404.9407 1421.5500 N12 N8 • 411.3732 0369101709I 411.1750 I N21 - Si f413 r0.2555 1008031 0.0603 I 413.8394 I417.9200 i rNl4I N21 • 414.4242 ioiO14roOO8l 0.0368 414.3604 I 421.5500 N15 N14 414.4119 [ 1 r414.4119 :1417.0600 N16 N14j 415.1503 119051000911 413.9690 1418.2500 N17 1-N16 416.6239 r0.2391 0.3230 T. 416.7078 419.9100 • N18 N17 417.408s 8 1 417.4088 1419.9100 N11 ' N21 f 414.5966 10.5754 0.4453 ! 414.4665 [418.7200 Thu1 : 415.5472 F n 415.5472 1 419.1900 N9 N8 - 410.5381 0.6021 0.8040 r 410.7401 419.9600 N10 • N9 412.0594 102403 [ö0020 f 411.8211 f-415.5500 I N01r. N10 413.3481 r0.0979 1 0.0008 r r 413.2510 .1417.0000 F No2 NO1 413.7051 [ 1 1 [ 413.7051 1-417.4900 14 APPENDIX D Facility Summary Report KING COUNTY. WASHINGTON, SURFACE WATER DESIGN MANUAL APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 1 - DETENTION PONDS Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed General Trash & Debris Any trash and debris which exceed 1 cubic foot Trash and debris cleared from site. per 1,000 square feet(this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Poisonous Vegetation Any poisonous or nuisance vegetation which No danger of poisonous vegetation may constitute a hazard to County personnel or where County personnel or the the public. public might normally be. (Coordination with Seattle-King County Health Department) Pollution Oil,gasoline,or other contaminants of one No contaminants present other than gallon or more or any amount found that could: a surface film. (Coordination with 1)cause damage to plant,animal,or marine life; . Seattle/King County Health 2)constitute a fire hazard;or 3)be flushed Department) downstream during rain storms. Unmowed Grass/ If facility is located in private residential area, When mowing is needed, Ground Cover mowing is needed when grass exceeds 18 grass/ground cover should be inches in height. In other areas,the general mowed to 2 inches in height. policy is to make the pond site match adjacent Mowing of selected higher use ground cover and terrain as long as there is no areas rather than the entire slope interference with the function of the facility. may be acceptable for some situations. Rodent Holes Any evidence of rodent holes if facility is acting Rodents destroyed and dam or as a dam or berm,or any evidence of water berm repaired. (Coordination with piping through dam or berm via rodent holes. Seattle/King County Health Department) Insects When insects such as wasps and hornets Insects destroyed or removed from interfere with maintenance activities. site. Tree Growth Tree growth does not allow maintenance access Trees do not hinder maintenance or interferes with maintenance activity(i.e.,slope activities. Selectively cultivate trees mowing,silt removal,vactoring,or equipment such as alders for firewood. movements). If trees are not interfering with access,leave trees alone. Side Slopes of Pond Erosion Eroded damage over 2 inches deep where Slopes should be stabilized by cause of damage is still present or where there using appropriate erosion control is potential for continued erosion. measure(s);e.g., rock reinforcement,planting of grass, compaction. Storage Area Sediment Accumulated sediment that exceeds 10%of the Sediment cleaned out to designed designed pond depth pond shape and depth;pond reseeded if necessary to control erosion. • Pond Dikes Settlements Any part of dike which has settled 4 inches lower Dike should be built back to the than the design elevation. design elevation. Emergency Rock Missing Only one layer of rock exists above native soil in Replace rocks to design standards. Overflow/Spillway area five square feet or larger,or any exposure of native soil at the top of out flow path of spillway. Rip-rap on inside slopes need not be replaced. 1998 Surface Water Design Manual 9'1.98 A-1 APPENDIX A MAINTENANCE STANDARDS FOR PRIN,'AFELY MAINTAINED DRAINAGE FACILITIES NO. 2 - INFILTRATION Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed General Trash&Debris See"Ponds"Standard No. 1 See"Ponds"Standard No. 1 Poisonous Vegetation See"Ponds"Standard No. 1 See"Ponds"Standard No. 1 Pollution See"Ponds"Standard No. 1 See"Ponds"Standard No. 1 Unmowed Grass/ See"Ponds"Standard No. 1 See"Ponds"Standard No. 1 Ground Cover Rodent Holes See"Ponds"Standard No. 1 See"Ponds"Standard No. 1 • Insects See"Ponds"Standard No. 1 See"Ponds"Standard No. 1 Storage Area Sediment A percolation test pit or test of facility indicates Sediment is removed and/or facility facility is only working at 90%of its designed is cleaned so that infiltration system capabilities. If two inches or more sediment is works according to design. present, remove. Sheet Cover(If Sheet cover is visible and has more that three Sheet cover repaired or replaced. Applicable) 1/4-inch holes in it. Sump Filled with Any sediment and debris filling vault to 10%of Clean out sump to design depth. Sediment and Debris depth from sump bottom to bottom of outlet pipe (If Applicable) or obstructing flow into the connector pipe. Filter Bags Filled with Sediment Sediment and debris fill bag more than 1/2 full. Replace filter bag or redesign and Debris system. Rock Filters Sediment and Debris By visual inspection, little or no water flows Replace gravel in rock filter. through filter during heavy rain storms. • Side Slopes of Pond Erosion See"Ponds"Standard No. 1 See"Ponds"Standard No. 1 Emergency Rock Missing See"Ponds"Standard No. 1 Overflow Spillway Settling Ponds and Sediment Remove when 6"or more. Vaults Note: Sediment accumulation of more than.25 inches per year may indicate excessive erosion is occurring upstream of the facility or that conveyance systems are not being properly maintained. The contributing drainage area should be checked for erosion problems or inadequate maintenance of conveyance systems if excessive sedimentation is noted in an infiltration facility. Check twice a year during first 2 years of operation;once a year thereafter. Clean manholes/catch basins, repair damaged inlets/outlets, clean trash racks. • • 9:1/9S 1998 Surface Water Design Manual A-2 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 3 -CLOSED DETENTION SYSTEMS (PIPES/TANKS) Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Storage Area Plugged Air Vents One-half of the cross section of a vent is blocked at Vents free of debris and any point with debris and sediment sediment Debris and Accumulated sediment depth exceeds 10%of the All sediment and debris Sediment diameter of the storage area for'/2 length of storage removed from storage area. vault or any point depth exceeds 15%of diameter. Example: 72-inch storage tank would require cleaning when sediment reaches depth of 7 inches for more than'/2 length of tank. Joints Between Any crack allowing material to be transported into All joint between tank/pipe Tank/Pipe Section facility sections are sealed Tank Pipe Bent Any part of tank/pipe is bent out of shape more than Tank/pipe repaired or replaced Out of Shape 10%of it's design shape to design. Manhole Cover Not in Place Cover is missing or only partially in place.Any open Manhole is closed. manhole requires maintenance. Locking Mechanism cannot be opened by one maintenance Mechanism opens with proper Mechanism Not person with proper tools. Bolts into frame have less tools. Working than 1/2 inch of thread (may not apply to self-locking lids.) • Cover Difficult to One maintenance person cannot remove lid after Cover can be removed and Remove applying 801bs of lift. Intent is to keep cover from reinstalled by one maintenance sealing off access to maintenance. person. Ladder Rungs King County Safety Office and/or maintenance person Ladder meets design standards Unsafe judges that ladder is unsafe due to missing rungs, allows maintenance person safe misalignment, rust, or cracks. access. Catch Basins See"Catch Basins"Standards No. 5 See"Catch Basins"Standards No. 5 1998 Surlacc \l;uuml 9,1.98 A-3 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 4-CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed General Trash and Debris Distance between debris build-up and bottom of All trash and debris removed. • (Includes Sediment) orifice plate is less than 1-1/2 feet. Structural Damage Structure is not securely attached to manhole wall Structure securely attached to and outlet pipe structure should support at least wall and outlet pipe. 1,000 lbs of up or down pressure. Structure is not in upright position(allow up to Structure in correct position. 10%from plumb). Connections to outlet pipe are not watertight and Connections to outlet pipe are show signs of rust. water tight; structure repaired or replaced and works as designed. Any holes--other than designed holes--in the Structure has no holes other structure. than designed holes. Cleanout Gate Damaged or Missing Cleanout gate is not watertight or is missing. Gate is watertight and works as designed. Gate cannot be moved up and down by one Gate moves up and down easily maintenance person. and is watertight. Chain leading to gate is missing or damaged. Chain is in place and works as designed. Gate is rusted over 50%of its surface area. Gate is repaired or replaced to meet design standards.. Orifice Plate Damaged or Missing Control device is not working properly due to Plate is in place and works as missing,out of place, or bent orifice plate. designed. Obstructions Any trash,debris, sediment, or vegetation Plate is free of all obstructions blocking the plate and works as designed. Overflow Pipe Obstructions Any trash or debris blocking(or having the Pipe is free of all obstructions potential of blocking)the overflow pipe. and works as designed. Manhole See"Closed Detention Systems"Standards No. 3 See"Closed Detention Systems' Standards No. 3 Catch Basin See"Catch Basins"Standards No. 5 See'Catch Basins"Standards No. 5 9.'1/98 1998 Surlacc Water Design Manual A-4 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 5 -CATCH BASINS Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed General Trash& Debris Trash or debris of more than 1/2 cubic foot which is No Trash or debris located (Includes Sediment) located immediately in front of the catch basin immediately in front of catch opening or is blocking capacity of the basin by basin opening. more than 10% Trash or debris(in the basin)that exceeds 1/3 the No trash or debris in the catch depth from the bottom of basin to invert the lowest basin. pipe into or out of the basin. Trash or debris in any inlet or outlet pipe blocking Inlet and outlet pipes free of more than 1/3 of its height. trash or debris. Dead animals or vegetation that could generate No dead animals or vegetation odors that could cause complaints or dangerous present within the catch basin. gases(e.g., methane). Deposits of garbage exceeding 1 cubic foot in No condition present which volume would attract or support the breeding of insects or rodents. Structure Damage to Corner of frame extends more than 3/4 inch past Frame is even with curb. Frame and/or Top Slab curb face into the street(If applicable). Top slab has holes larger than 2 square inches or Top slab is free of holes and cracks wider than 1/4 inch(intent is to make sure cracks. all material is running into basin). Frame not sitting flush on top slab, i.e., separation Frame is sitting flush on top of more than 3/4 inch of the frame from the top slab. slab. Cracks in Basin Walls/ Cracks wider than 1/2 inch and longer than 3 feet, Basin replaced or repaired to Bottom any evidence of soil particles entering catch basin design standards. through cracks,or maintenance person judges that structure is unsound. Cracks wider than 1/2 inch and longer than 1 foot No cracks more than 1/4 inch at the joint of any inlet/outlet pipe or any evidence wide at the joint of inleUoutlet of soil particles entering catch basin through pipe. cracks. Sediment/ Basin has settled more than 1 inch or has rotated Basin replaced or repaired to Misalignment more than 2 inches out of alignment. design standards. 1993 SurfaCC\\'alcr I n \lanual 9;I;qg A-5 APPENDIX .A MAIN"I F;NAWE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 5-CATCH BASINS (CONTINUED) Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed • Fire Hazard Presence of chemicals such as natural gas, oil and No flammable chemicals gasoline. present. Vegetation Vegetation growing across and blocking more than No vegetation blocking opening 10%of the basin opening. to basin. Vegetation growing in inlet/outlet pipe joints that is No vegetation or root growth more than six inches tall and less than six inches present. apart. Pollution Nonflammable chemicals of more than 1/2 cubic foot No pollution present other than per three feet of basin length. surface film. Catch Basin Cover Cover Not in Place Cover is missing or only partially in place.Any open Catch basin cover is closed catch basin requires maintenance. Locking Mechanism Mechanism cannot be opened by on maintenance Mechanism opens with proper Not Working person with proper tools. Bolts into frame have less tools. than 1/2 inch of thread. Cover Difficult to One maintenance person cannot remove lid after Cover can be removed by one Remove applying 80 lbs. of lift; intent is keep cover from maintenance person. sealing off access to maintenance. Ladder Ladder Rungs Ladder is unsafe due to missing rungs, misalignment, Ladder meets design standards Unsafe rust,cracks,or sharp edges. and allows maintenance person safe access. Metal Grates Grate with opening wider than 7/8 inch. Grate opening meets design (If Applicable) standards. Trash and Debris Trash and debris that is blocking more than 20%of Grate free of trash and debris. grate surface. Damaged or Grate missing or broken member(s)of the grate. Grate is in place and meets Missing. design standards. NO. 6 DEBRIS BARRIERS (E.G., TRASH RACKS) Maintenance Defect Condition When Maintenance is Needed Results Expected When Components Maintenance is Performed. General Trash and Debris Trash or debris that is plugging more than 20%of Barrier clear to receive capacity the openings in the barrier. flow. Metal Damaged/Missing Bars are bent out of shape more than 3 inches. Bars in place with no bends more Bars. than 3/4 inch. Bars are missing or entire barrier missing. Bars in place according to design. Bars are loose and rust is causing 50%deterioration Repair or replace barrier to to any part of barrier. design standards. 9. 1,9`t 1998 Surface Water Design M;mu,al A-6 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 7 - ENERGY DISSIPATERS Maintenance Defect Conditions When Maintenance is Needed Results Expected When Components Maintenance is Performed. External: Rock Pad Missing or Moved Only one layer of rock exists above native soil in Replace rocks to design Rock area five square feet or larger,or any exposure of standards. native soil. Dispersion Trench Pipe Plugged with Accumulated sediment that exceeds 20%of the Pipe cleaned/flushed so that it Sediment design depth. matches design. Not Discharging Visual evidence of water discharging at Trench must be redesigned or Water Properly concentrated points along trench(normal condition rebuilt to standards. is a"sheet flow"of water along trench). Intent is to prevent erosion damage. Perforations Over 1/2 of perforations in pipe are plugged with Clean or replace perforated pipe. Plugged. debris and sediment. Water Flows Out Maintenance person observes water flowing out Facility must be rebuilt or Top of"Distributor" during any storm less than the design storm or its redesigned to standards. Catch Basin. causing or appears likely to cause damage. Receiving Area Water in receiving area is causing or has potential No danger of landslides. Over-Saturated of causing landslide problems. Internal: Manhole/Chamber Worn or Damaged Structure dissipating flow deteriorates to 1/2 or Replace structure to design Post. Baffles, Side original size or any concentrated worn spot standards. of Chamber exceeding one square foot which would make structure unsound. Other Defects See"Catch Basins"Standard No.5 See"Catch Basins"Standard No. 5 • IO98 Surface \\;rtrr Design \hinu,tl 1) 1;98 A-7 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 8 - FENCING Maintenance Defect Conditions When Maintenance is Needed Results Expected When Components Maintenance is Performed General Missing or Broken Any defect in the fence that permits easy entry Parts in place to provide adequate Parts to a facility. security. Erosion Erosion more than 4 inches high and 12-18 No opening under the fence that inches wide permitting an opening under a exceeds 4 inches in height. fence. Wire Fences Damaged Parts Post out of plumb more than 6 inches. Post plumb to within 1-1/2 inches. Top rails bent more than 6 inches. Top rail free of bends greater than 1 inch. Any part of fence(including post,top rails, and Fence is aligned and meets design fabric)more than 1 foot out of design alignment. standards. Missing or loose tension wire. Tension wire in place and holding fabric. Missing or loose barbed wire that is sagging Barbed wire in place with less than more than 2-1/2 inches between posts. 3/4 inch sag between post. Extension arm missing,broken, or bent out of Extension arm in place with no shape more than 1 1/2 inches. bends larger than 3/4 inch. Deteriorated Paint or Part or parts that have a rusting or scaling Structurally adequate posts or Protective Coating condition that has affected structural adequacy. parts with a uniform protective coating. Openings in Fabric Openings in fabric are such that an 8-inch- No openings in fabric. diameter ball could fit through. NO. 9 -GATES Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed General Damaged or Missing Missing gate or locking devices. Gates and Locking devices in Members place. Broken or missing hinges such that gate cannot Hinges intact and lubed. Gate is be easily opened and closed by a maintenance working freely. person. Gate is out of plumb more than 6 inches and Gate is aligned and vertical. more than 1 foot out of design alignment. Missing stretcher bar, stretcher bands, and ties. Stretcher bar,bands and ties in place. Openings in Fabric See"Fencing"Standard No. 8 See"Fencing"Standard No. 8 9 1.98 1998 Surl:acc Water Design Manual A-8 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 10 -CONVEYANCE SYSTEMS (PIPES & DITCHES) Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Pipes Sediment&Debris Accumulated sediment that exceeds 20%of the Pipe cleaned of all sediment diameter of the pipe. and debris. Vegetation Vegetation that reduces free movement of water All vegetation removed so water through pipes. flows freely through pipes. Damaged Protective coating is damaged; rust is causing Pipe repaired or replaced. more than 50%deterioration to any part of pipe. Any dent that decreases the cross section area of Pipe repaired or replaced. pipe by more than 20%. Open Ditches Trash&Debris Trash and debris exceeds 1 cubic foot per 1,000 Trash and debris cleared from square feet of ditch and slopes. ditches. Sediment Accumulated sediment that exceeds 20%of the Ditch cleaned/flushed of all design depth. sediment and debris so that it matches design. Vegetation Vegetation that reduces free movement of water Water flows freely through through ditches. ditches. Erosion Damage to See"Ponds"Standard No. 1 See"Ponds"Standard No. 1 Slopes Rock Lining Out of Maintenance person can see native soil beneath Replace rocks to design Place or Missing(If the rock lining. standards. Applicable). Catch Basins See"Catch Basins: Standard No. 5 See"Catch Basins"Standard No. 5 Debris Barriers See"Debris Barriers"Standard No.6 See"Debris Barriers"Standard (e.g.,Trash Rack) No.6 NO. 11 -GROUNDS (LANDSCAPING) Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed General Weeds Weeds growing in more than 20%of the landscaped Weeds present in less than 5% (Nonpoisonous) area(trees and shrubs only). of the landscaped area. Safety Hazard Any presence of poison ivy or other poisonous No poisonous vegetation vegetation. present in landscaped area. Trash or Litter Paper, cans, bottles,totaling more than 1 cubic foot Area clear of litter. within a landscaped area(trees and shrubs only) of 1.000 square feet Trees and Shrubs Damaged Limbs or parts of trees or shrubs that are split or Trees and shrubs with less than broken which affect more than 25%of the total 5%of total foliage with split or foliage of the tree or shrub. broken limbs. Trees or shrubs that have been blown down or Tree or shrub in place free of knocked over injury. Trees or shrubs which are not adequately supported Tree or shrub in place and or are leaning over,causing exposure of the roots. adequately supported; remove any dead or diseased trees. 1998 Surface Water Design Manual 9.1,98 A-9 APPENDIX A MAINTENANCE STANDARDS FOR PRIVA[EL.Y MAINTAINED DRAINAGE FACILITIES NO. 12 -ACCESS ROADS/ EASEMENTS Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed General Trash and Debris Trash and debris exceeds 1 cubic foot per 1,000 Roadway free of debris which square feet i.e.,trash and debris would fill up could damage tires. one standards size garbage can. Blocked Roadway Debris which could damage vehicle tires(glass Roadway free of debris which or metal). could damage tires. • Any obstruction which reduces clearance above Roadway overhead clear to 14 feet road surface to less than 14 feet. high. Any obstruction restricting the access to a 10 to Obstruction removed to allow at 12 foot width for a distance of more than 12 feet least a 12 foot access. or any point restricting access to less than a 10 foot width. Road Surface Settlement, Potholes, When any surface defect exceeds 6 inches in Road surface uniformly smooth Mush Spots, Ruts depth and 6 square feet in area. In general, any with no evidence of settlement, surface defect which hinders or prevents potholes, mush spots, or ruts. maintenance access. Vegetation in Road Weeds growing in the road surface that are Road surface free of weeds taller Surface more than 6 inches tall and less than 6 inches than 2 inches. tall and less than 6 inches apart within a 400- square foot area. Modular Grid Build-up of sediment mildly contaminated with Removal of sediment and disposal Pavement petroleum hydrocarbons. in keeping with Health Department recommendations for mildly contaminated soils or catch basin sediments. Shoulders and Erosion Damage Erosion within 1 foot of the roadway more than 8 Shoulder free of erosion and Ditches inches wide and 6 inches deep. matching the surrounding road. • Weeds and Brush Weeds and brush exceed 18 inches in height or Weeds and brush cut to 2 inches hinder maintenance access. in height or cleared in such a way as to allow maintenance access. I 9,'1;9R 1998 Surface Wafer Design !Manual ,A-1O APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 13-WATER QUALITY FACILITIES A.) Biofiltration Swale Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Biofiltration swale Sediment Accumulation Sediment depth exceeds 2-inches No sediment deposits on grass on Grass Layer layer of the bio-swale,which would impede filtration of runoff. Vegetation When the grass becomes excessively tall Vegetation is mowed or nuisance (greater than 10-inches);when nuisance weeds vegetation is eradicated, such that and other vegetation starts to take over. flow not impeded. Grass should be mowed to a height between 4 inches and 9 inches. Inlet Outlet Pipe Inlet/outlet pipe clogged with sediment and/or No clogging or blockage in the inlet debris, and outlet piping. -- Trash and Debris Trash and debris accumulated in the bio-swale. Trash and debris removed from Accumulation bioswale. Erosion/Scouring Where the bio-swale has eroded or scoured Bioswale should be re-graded and the bottom due to flow channelization, or higher re-seeded to specification,to flows. eliminated channeled flow. Overseeded when bare spots are evident. NO. 13-WATER QUALITY FACILITIES (CONTINUED) B.) Grasslined Filter Strips Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Filter Strip Sediment Accumulation Sediment depth exceeds 2 inches. No sediment deposits on grass on Grass Layer layer of the filter strip,which would impede filtration runoff. Vegetation When the grass becomes excessively tall Vegetation is mowed or nuisance (greater than 10-inches);when nuisance weeds vegetation is eradicated, such that and other vegetation starts to take over. flow not impeded. Grass should be mowed to a height between 4 inches and 9 inches. Trash and Debris Trash and debris accumulated on the filter Trash and Debris removed from Accumulation strip. filter. • Erosion/Scouring Where the filter strip has eroded or scoured Strip should be re-graded and re- due to flow channelization. or higher flows. seeded specification,to eliminate channeled flow. Overseeded when bare spots are evident. V-Notch Pipe Weir When the V-Notch pipe becomes damaged or Cleaned and properly functioning clogged with sediment/debris weir,such that flows uniformly spread 1998 Surracc Water De.izn Manual 0;1,98 A-11 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES C.)Wetponds Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Wetpond Vegetation Vegetation such as grass and weeds need to be Vegetation should be mowed to mowed when it starts to impede aesthetics of pond. 4 to 5 inches in height. Trees Mowing is generally required when height exceeds and bushes should be removed 18-inches. Mowed vegetation should be removed where they are interfering with from areas where it could enter the pond,either pond maintenance activities. when the pond level rises,or by rainfall runoff. Trash and Debris Accumulation that exceeds 1 CF per 1000-SF of Trash and debris removed from pond area. pond. Inlet/Outlet Pipe Inlet/Outlet pipe clogged with sediment and/or No clogging or blockage in the debris material. inlet and outlet piping. Sediment Sediment accumulations in pond bottom that Removal of sediment from pond Accumulation in Pond exceeds the depth of sediment zone plus 6-inches, bottom. Bottom usually the first cell. Oil Sheen on Water Prevalent and visible oil sheen. Removal of sediment from pond bottom. Erosion Erosion of the pond's side slopes and/or scouring of Slopes should be stabilized by the pond bottom,that exceeds 6-inches, or where using proper erosion control continued erosion is prevalent. measures, and repair methods. Settlement of Pond Any part of these components that has settled 4- Dike/berm is repaired to Dike/Berm inches or lower than the design elevation, or specifications. inspector determines dike/berm is unsound. ski Rock Window Rock window is clogged with sediment. Window is free of sediment and debris. Overflow Spillway Rock is missing and soil is exposed at top of Replace rocks to specifications. spillway or outside slope. 9,I;98 1998 Surlhce Water Design Manual A-12 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 13 -WATER QUALITY FACILITIES (CONTINUED) D.) Wetvaults Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Wetvault Trash/Debris Trash and debris accumulated in vault, pipe or Trash and debris removed from Accumulation inlet/outlet, (includes floatables and non- vault. floatables). Sediment Accumulation Sediment accumulation in vault bottom that Removal of sediment from vault. in Vault exceeds the depth of the sediment zone plus 6- inches. Damaged Pipes Inlet/outlet piping damaged or broken and in Pipe repaired and/or replaced. need of repair. Access Cover Cover cannot be opened or removed, especially Pipe repaired or replaced to Damaged/Not Working by one person. proper working specifications. Vault Structure Vault: Cracks wider than 1/2-inch and any No cracks wider than 1/4-inch at Damaged evidence of soil particles entering the structure the joint of the inlet/outlet pipe. through the cracks, or maintenance/inspection Vault is determined to be personnel determines that the vault is not structurally sound. structurally sound. Baffles Baffles corroding,cracking,warping and/or Repair or replace baffles to showing signs of failure as determined by specifications. maintenance/inspection staff. Access Ladder Damage Ladder is corroded or deteriorated, not functioning Ladder replaced or repaired to properly, missing rungs, has cracks and/or specifications, and is safe to misaligned. use as determined by inspection personnel. IOW I 1993 Surface Vvalcr Design Manual 9..1.98 A-13 1 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 13 -WATER QUALITY FACILITIES (CONTINUED) E.) Sand Filters Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Above Ground Sediment Sediment depth exceeds 1/2-inch. No sediment deposit on grass Accumulation on Grass layer of sand filter which would Layer impede permeability of the filter section. Trash and Debris Trash and debris accumulated on sand filter bed. Trash and debris removed from •• Accumulations sand filter bed. Sediment/Debris in When the yard drain CB's and clean-out become Sediment, material from the Yard Drains/Clean- full or partially plugged with sediment and/or CB's and clean-outs removed. Outs] debris. Vegetation When the grass becomes excessively tall(greater Vegetation is mowed or than 6-inches);when nuisance weeds and other nuisance vegetation is vegetation starts to take over. eradicated, such that flow is not impeded. Sand Filter Media Drawdown of water through the sand filter media, Usually requires replacement of takes longer than 24-hours,and/or flow through top 6 to 12-inches of media. the overflow pipes occurs frequently. May require replacement of entire sand filter section, depending on section. Prolonged flows Sand is saturated for prolonged periods of time Limit the low,continuous flows (several weeks)and does not dry out between to a small portion of the facility I storms due to continuous base flow or prolonged by using a low wooden divider or flows from detention facilities. slightly depressed sand surface. Short Circuiting When flows become concentrated over the sand Flow and percolation of water filter rather than dispersed. through the sand filter is uniform and dispersed across the filter section. Erosion Damage to Erosion over 2-inches deep where cause of Slopes should be stabilized by I. Slopes damage is prevalent or potential for continued using proper erosion control erosion is evident. measures. Rock Pad Missing or Soil beneath the rock is visible. Replace or rebuild the rock pad Out of Place to design specifications. V-Notch Pipe Weir When the V-Notch pipe becomes damaged or Clean and properly functioning clogged with sediment/debris. weir,such that flows uniformly ---, spread. Damaged Pipes Any part of the piping that is crushed or deformed Pipe repaired or replaced. more than 20%or any other failure to the piping. Below Ground Sediment Sediment depth exceeds 112-inch. No sediment deposits on sand Vault. Accumulation on Sand filter section,which would Media Section impede permeability of the filter section. Sediment Sediment depth exceeds 6-inches in vault bottom. No sediment deposit in the first Accumulation in Vault chamber of the vault. Trash/Debris Trash and debris accumulated in vault,or pipe Trash and debris removed from Accumulation inlet/outlet,floatables and non-floatables vault, and inlet/outlet piping. Sediment in Drain When drain pipes. cleanouts,and yard drains Remove the material from the Pipes/Yard Drains/ become full with sediment and/or debris. facilities. Cleanouts ``" 9.1,98 1998 Surface Water Design Manual A-14 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 13 -WATER QUALITY FACILITIES (CONTINUED) E.) Sand Filters (Continued) Maintenance Defect Conditions When Maintenance is Needed• Results Expected When Component Maintenance is Performed Below Ground Short Circuiting When seepage!flow occurs along the vault walls Sand filter media section re-laid Vault(Continued) and corners. and compacted along perimeter of vault to form a semi-seal. Vertical Riser Pipes Plugged,failure due to cracking deformation. Flows Clean out the riser pipe; replace tend to back-up in first chamber of the vault. pipe as needed. Damaged Pipes Inlet or outlet piping damaged or broken and in Pipe repaired and/or replaced. need of repair. Access Cover Cover cannot be opened, one person cannot open Cover repaired to proper Damaged/Not the cover, corrosion/deformation of cover. working specifications or Working replaced. Vault Structure Cracks wider than 1/2-inch and any evidence of soil Vault replaced or repaired to Damaged; Includes particles entering the structure through the cracks, design specifications. Cracks in Walls, or maintenance/inspection personnel determines Bottom, Damage to that the vault is not structurally sound. Frame and/or Top Slab. • Cracks wider than 1/2-inch at the joints of any inlet/ No cracks more than 1/4-inch outlet pipe or any evidence of soil particles entering wide at the joint of the inlet/ the vault through the walls. outlet pipe. Baffles Baffles corroding, cracking,warping and/or showing Repair or replace baffles to signs of failure as determined by maintenance/ specifications. inspection person. Access Ladder Ladder is corroded or deteriorated, not functioning Ladder replaced or repaired to Damaged properly, missing rungs, cracks, and misaligned. specifications, and is safe to use as determined by inspection personnel. I • 1998 Surface Water Design Nlanual 9,1;'98 A-IS APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 13 -WATER QUALITY FACILITIES (CONTINUED) F.) Leaf Compost Filters Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Above Ground Sediment Sediment depth exceeds 0.25-inches. No sediment deposits on fabric Open Swale accumulation on Geo- layer which would impede Textile/media permeability of the fabric. Trash and debris Trash and debris accumulated on compost filter Trash and debris removed from accumulations bed. compost filter bed. Sediment/debris in When the yard drain CB's and clean-outs become Remove the accumulated drain/yard drains! full of sediment and/or debris. material from the facility. clean-outs. Vegetation Vegetation impending flow through section,or Vegetation is mowed or encroaching into compost media. eradicated such that flow is no longer impeded. Leaf Compost Media Drawdown of water through the leaf compost, Replace media with new to takes longer than 12-hours,and/or flow through design specifications, in addition the overflow pipes occurs frequently. to replacing fabric. Short-Circuiting When Channeled flow occurs over the leaf media; Flow is uniform over the entire and where flow perks through the media at the width of the media section, and baffles. concentrated percolation does not occur at the baffle walls. Media needs to be graded and re-set at the baffles to form a seal.Weir plate may need to be adjusted in addition. Erosion Damage to Eroded damage over 2-inches deep where cause Slopes should be stabilized by Slopes of damage is prevalent or potential for continued using proper erosion control erosion is prevalent. measures, Damaged Geo-Textile When fabric is torn,deteriorated, raveled,etc. Fabric replaced as necessary. Fabric. Rock Pad Missing or Soil beneath the pad is visible. Replace or rebuild the rock pad out of place to design standards. Damaged Pipes Any part of the pipe system that is crushed, Pipe repaired or replaced. damage due to corrosion,and/or settlement. V-Notch Weir Flow is not being uniformly spread over filter Clean, repair or replace the weir Assemblies media. systems. Below Ground Sediment Sediment depth exceeds 0.25-inches. No sediment deposits on fabric Vault Accumulation on Geo- layer which would impede Textile/Media. permeability of the fabric and compost media. Sediment Sediment depth exceeds 6-inches in first chamber No sediment deposits in vault Accumulation in Vault bottom of first chamber. Trash!Debris Trash and debris accumulated on compost filter Trash and debris removed from Accumulation bed. the compost filter bed. Sediment in Drain When drain pipes. clean-outs,yard drains become Remove the accumulated Pipes/Yard Drains/ full with sediment and!or debris. material from the facilities. Clean-Outs `,.l 98 1998 Surface\\,iter Design Manual A-16 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 13 -WATER QUALITY FACILITIES (CONTINUED) F.) Leaf Compost Filter(Continued) Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Below Ground Leaf Compost Media Drawdown of water through the leaf compost,takes Replace media with new longer than 12-hours, and/or overflow occurs compost to specifications, in frequently. addition to replacing fabric. • Short Circuiting When seepage occurs along the vault wall and Percolation of water occurs corners occur. along the walls and corners and not through the media section. Media needs to be re-set along the vault wall and corners to form a semi-seal. Plugged/Damaged Flow tends to backup unusually high in the first Clean out the elbow fittings and/ Elbows chamber of the vault. or replace if damaged. Damaged Geo-Textile Fabric is torn,deteriorated, raveled,etc. Fabric replaced as necessary. Fabric Rock Pad Missing or Soil beneath the pad is visible. Replace or rebuild the rock pad Out of Place to design standards. Damaged Pipes Any part of the pipes that are crushed,damaged Pipe repaired and/or replaced. due to corrosion and/or settlement. Access Cover Cover cannot be opened,one person cannot open Cover repaired to proper Damaged/Not the cover,corrosion/deformation of cover. working specifications or Working replaced. V-Notch Weir Flow does not spread uniformly over filter media by Clean, repair and/or replace the Assemblies weir section. weir plate section,or adjust height. Vault Structure Cracks wider than 1/2-inch and any evidence of soil Vault replaced or repaired to Includes Cracks in particles entering the structure through the cracks, design specifications. Wall, Bottom, or maintenance/inspection personnel determines Damage to Frame that the vault is not structurally sound. and/or Top Slab • Baffles Baffles corroding, cracking warping, and/or showing Repair or replace baffles to signs of failure as determined by maintenance/ specification. inspection person. Access Ladder Ladder is corroded or deteriorated, not functioning Ladder replaced or repaired and Damaged properly, missing rungs, cracks, and misaligned. meets specifications, and is safe to use as determined by inspection personnel. Cracks wider than 1/2-inch at the joint of any No cracks more than 1/4-inch inlet/outlet pipe or any evidence of soil particles wide at the joint of the inlet/ entering the vault through the walls. outlet pipe. 1998 Surface \alar Design Manual 9,1/98 A-17 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 13 -WATER QUALITY FACILITIES (CONTINUED) G.) Infiltration Ponds Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Infiltration Pond Vegetation Vegetation such as grass and weeds needs to be Vegetation should be mowed to mowed when it starts to impede infiltration function. 2-inches in height.Trees and Mowing is generally required when height exceeds bushes should be removed 12 inches. where they impact the infiltrating area of the pond. Sand Filter Layer Sand filter layer has sediment deposits that exceeds Remove sediment and top layer 1/2-inch or the infiltration rate of the sand layer is of sand, and replace in kind per less than 2 in/hr. specification. Sediment Sediment accumulations in pond bottom that Removal of sediment from pond Accumulation in exceeds 1/2-inch in depth or percolation test of the bottom. Pond Bottom pond indicates facility is only working at 90%of it's design percolation rate. Trash and Debris Accumulation that exceeds 1-CF per 1,000-SF of Trash and Debris removed from pond area. pond. Inlet/Outlet Pipe Inlet/outlet pipe clogged with sediment and/or No clogging or blockage in the debris material. inlet and outlet piping. Erosion Erosion of the pond's side slope and/or scouring of Slopes should be stabilized by the pond bottom, that exceeds 2-inches,or where using proper erosion control potential for continued erosion is prevalent. measures and repair methods. Sediment of Pond Any part of these components that has settled 4- Slopes should be stabilized by Dike/Berm inches or lower than the design elevation,or where using proper erosion control potential for continued erosion is prevalent. measures and repair methods. Rock Window Rock window is clogged with sediment. Window is free of sediment and debris. Overflow Spillway Rock is missing and soil is exposed Replace rocks to specifications. Infiltration Vault/ Sediment Tanks: Sediment depth exceeds 6-inches in depth. No sediment deposits in tank Tank Accumulation in bottom. Vault Trash and Debris Trash and debris accumulated in tank,vault or Trash and debris removed from Accumulation connecting pipe. Includes floatables and non- each facility. floatables. Access Cover Cover cannot be opened or removed,especially by Cover repaired or replaced to Damaged/Not one person. proper working specifications or Working replaced. • Tank or Vault Tank:Joints between tank sections failing, such that Tank replaced or repaired to Structure Damaged leakage occurs and. or material being washed design specifications. through into facility: or maintenance/inspection person determines the tank is not structurally sound. 9.1.98 1993 Surface Wittier Design Manual A-18 APPFNDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 13 -WATER QUALITY FACILITIES (CONTINUED) G.) Infiltration Ponds (Continued) Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Infiltration Vault/ Tank or Vault Structural Vault: Cracks wider than 1/2-inch and any Tank replaced or repaired to Tank Damage evidence of soil particles entering the structure design specifications. through the cracks,or maintenance inspection personnel determines that the vault is not structurally sound. Access Ladder Damaged Ladder is corroded or deteriorated, not Ladder replaced or repaired to functioning properly, missing rungs, has cracks specifications, and is safe to and/or misaligned. use as determined by inspection personnel. 1998 Sul-lace Water I)csi n I\Ianu;il 9.1.98 A-19 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 14-OIL CONTROL FACILITIES A.) Oil/Water Separators Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed. API Type OWS Monitoring Inspection of discharge water for obvious signs Effluent discharge from vault of poor water quality. should be clear with out thick visible sheen. • Sediment Accumulation Sediment depth in bottom of vault exceeds 6- No sediment deposits on vault inches in depth. bottom which would impede flow through the vault and separation efficiency. Trash and Debris Trash and debris accumulation in vault, or pipe Trash and debris removed from Accumulation inlet/outlet,floatables and non-floatables. vault,and inlet/outlet piping. Oil Accumulation Oil accumulations that exceed 1-inch, at the Extract oil from vault by surface of the water vactoring. Disposal in accordance with state and local rules and regulations. Damaged Pipes Inlet or outlet piping damaged or broken and in Pipe repaired or replaced. need of repair. Access Cover Damaged/ Cover cannot be opened, one person cannot Cover repaired to proper Not Working open the cover,corrosion/deformation of cover. working specifications or replaced. Vault Structure Damage- Cracks wider than 1/2-inch and any evidence of Vault replaced or repaired to Includes Cracks in Walls soil particles entering the structure through the design specifications. Bottom, Damage to cracks, or maintenance/inspection personnel Frame and/or Top Slab determines that the vault is not structurally sound. Baffles Baffles corroding,cracking,warping and!or Repair or replace baffles to showing signs of failure as determined by specifications. maintenance!inspection person. Access Ladder Damaged Ladder is corroded or deteriorated, not Ladder replaced or repaired and functioning properly, missing rungs, cracks, and meets specifications,and is misaligned. safe to use as determined by inspection personnel. Cracks wider than 1/2-inch at the joint of any No cracks more than 1/4-inch inlet/outlet pipe or any evidence of soil particles wide at the joint of the inlet/ entering the vault through the walls. outlet pipe. CPS-Type OWS Monitoring Inspection of discharge water for obvious signs Effluent discharge from vault of poor water quality. should be clear with no thick visible sheen. Sediment Accumulation Sediment depth in bottom of vault exceeds 6- No sediment deposits on vault inches in depth and/or visible signs of sediment bottom and plate media,which on plates. would impede flow through the vault and separation efficiency. Trash and Debris Trash and debris accumulated in vault, or pipe Trash and debris removed from Accumulation inlet/outlet,floatables and non-floatables. vault, and inlet/outlet piping. Oil Accumulation Oil accumulation that exceeds 1-inch at the Extract oil from vault by water surface vactoring methods. Clean coalescing plates by thoroughly rinsing and flushing. Should be no visible oil depth on water. 9:1 1998 Surface Water Design Manual A-20 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 14 -OIL CONTROL FACILITIES (CONTINUED) A.) Oil/Water Separators (Continued) • Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Damaged Coalescing Plate media broken.deformed, cracked and/or Replace that portion of media Plates showing signs of failure. pack or entire plate pack • depending on severity of failure. Damaged Pipes Inlet or outlet piping damaged or broken and in need Pipe repaired and or replaced. of repair. Baffles Baffles corroding, cracking,warping and/or showing Repair or replace baffles to signs of failure as determined by maintenance/ specifications. inspection person. • Vault Structure Cracks wider than 1/2-inch and any evidence of soil Vault replaced or repaired to Damage-Includes particles entering the structure through the cracks, design specifications. Cracks in Walls, or maintenance inspection personnel determines Bottom, Damage to that the vault is not structurally sound. Frame and/or Top Slab Access Ladder Ladder is corroded or deteriorated, not functioning Ladder replaced or repaired and Damaged properly, missing rungs, cracks, and misaligned. meets specifications, and is safe to use as determined by • inspection personnel. Cracks wider than 1/2-inch at the joint of any inlet/ No cracks more than 1/4-inch outlet pipe or any evidence of soil particles entering wide at the joint of the inlet/ the vault through the walls. outlet pipe. B.) Catch Basin Inserts Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Catch Basin Sediment When sediment forms a cap over the insert media of No sediment cap on the insert Accumulation the insert and/or unit. media and it's unit. Trash and Debris Trash and debris accumulates on insert unit creating Trash and debris removed from Accumulation a blockage/restriction. insert unit. Runoff freely flows into catch basin. Inspection Inspection of media insert is required. Effluent water from media insert is free of oils and has no visible sheen. Media Insert-Water Catch basin insert is saturated with water,which no Remove and replace media Saturated longer has the capacity to absorb. insert Media Insert-Oil Media oil saturated due to petroleum spill that drains Remove and replace media Saturated into catch basin. insert. General Regular interval replacement due to typical average Remove and replace media at life of media insert product. regular intervals,depending on insert product. 1998 Surface Wafer Dcsi n !Manual 9,1,'98 A-21 APPENDIX B Stormwater Reference Documents Soils Hydrologic Group of Soils in King County B-1 SCS Western Washington Runoff Curve Numbers B-2 Design Storm Precipitation Values B-3 Geotechnical Engineering Study by Icicle Creek Engineers. B-4 Coal Mine Hazard Areas Map B-5 Aquifer Protection Zones Map B-6 Erosion Hazard Areas Map B-7 Seismic Hazard Areas Map B-8 Landslide Hazard Area Map B-9 Wetland Evaluation/Habitat Study B-10 Downstream Conveyance Map B-11 Water and Land Resources — Stormwater Complaints B-12 NASchweikl&Associates, pile BECLAN PLACE Civil Engineering,Project Management&Consulting 4 705 South 9th Street Phone: (253)272-4451 . Suite#303 Fax: (253)272-4.495 SCS SOILS MAP Tacoma,Washington 98405 bschweikl msn.com o •• I(_^—/ .z • Ile ". • ,.. , 3• I .L.-•� t • Li,.....---.? J t •x -.._...714.•.••• • : ' ,„ • r+ 4 '3::: .t :. ' gh1a.�. t x:15 >;•. w • ' • • • 1 • - 1'•-... __3 • ( • .• ,I 1.11(\. • •: ; ` �� , ,i • .- `t . •• • ' ' ,S . frailer >s; :• n• `� . • 11 • EIB i �: :.� w. • . . ., , n ;� ,i ; 11 • ar:�r. •. • •, • • • ti b it 8 •ii�tyi" •' `_ter- • fit'_ i • • •'- 4. • •• a ••.• •' • • ► • SIT ••••••• I •. • 1 �" • t • . N ••1 t e• w I.: • •• 1 P • a, • • • \1 e 1 e .t • I.)V. ;i• e • • 1 1 t�i4 6j �`'��• •.!:4. i 1 I :i •• ••i J`'f.8.''''..4 L�t`` .r.,,�..•w.• -/^^ . -` s.5 Tr • •�Ct_/:• • s 1:,•// ••I e :li la p J 6 -. I. . • ..44\ • •,i• tESCR:Pt':'NS ::F THE SCILS This section describes the soil series and mapping Alderwood soils are used for timber, pasture, units in the King County Area. Each soil series is berries, row crops, and urban development. They are described and then each mapping unit in that series. the most extensive soils in the survey area. Unless it is specifically mentioned otherwise, it is to be assumed that what :s stated about the soil series Alderwood gravelly sandy loam, 6 to 15 percent holds true for the mapping units in that series. Thus, slopes AgC) .--This soil is roiling. Areas are to get full information about any one mapping unit, it irregular in shape and range from 10 to about 600 is necessary to read both the description of the mapping acres in size. unit and the description of the soil series to which it Representative profile of Alderwood gravelly • belongs. sandy loam, 6 to 15 percent slopes, in woodland, 450 An important part of the description of each soil feet east and 1,300 feet south of the north quarter series is the soil profile, that is, the sequence of corner of sec. 15, T. 24 N., R. 6 E.: layers from the surface downward to rock or other underlying material. Each series contains two Ai--0 to 2 inches, very dark brown (10YR 2/2) gravelly descriptions of this profile. The first is brief and in sandy loam, dark grayish brown (10YR 4/2) dry; terms familiar to the layman. The second, detailed and weak, fine, granular structure; slightly hard, in technical terms, is for scientists, engineers, and friable, nonsticky, nonplastic; many roots; others who need to make thorough and precise studies strongly acid; abrupt, wavy boundary. 1 to 3 of soils. Unless it is otherwise stated, the colors inches thick. given in the descriptions are those of a moist soil. B2--2 to 12 inches, dark-brown (10YR 4/3) gravelly sandy As mentioned in the section "How This Survey Was loam, brown (10YR 5/3) dry; moderate, medium, Made," not all mapping units are members of a soil subangular blocky structure; slightly hard, series. Urban land, for example, does not belong friable, nonsticky, nonplastic; many roots; to a soil series, but nevertheless, is listed in strongly acid; clear, wavy boundary. 9 to 14 alphabetic order along with the soil series. inches thick. Following the name of each mapping unit is a Symbol B3--12 to 27 inches, grayish-brown (2.5Y 5/2) gravelly in parentheses. This SYmbol identifies the mapping sandy loam, light gray (2.5Y 7/2) dry; many, unit on the detailed soil map. Listed at the end of medium, distinct mottles of light olive brown each description of a mapping unit is the capability (2.5Y 5/6); hard, friable, nonsticky, nonplastic; unit and woodland group in which the mapping unit has many roots; medium acid; abrupt, wavy boundary. 12 been placed. The woodland designation and the page for to 23 inches thick. the description of each capability unit can be found by IIC--27 to 660 inches, grayish-brown (2.5Y 5/2), weakly • referring to the "Guide to Mapping Units" at the back of to strongly consolidated till, light gray (2.5Y this survey. 7/2) dry; common, medium, distinct mottles of The acreage and proportionate extent of each mapping light olive brown and yellowish brown (2.5Y 5/6 unit are shown in table 1. Many of the terms used in and 10YR 5/6); massive; no roots; medium describing soils can be found in the Glossary at the end acid. Many feet thick. of this survey, and more detailed information about the terminology and methods of soil mapping can be obtained The A horizon ranges from very dark brown to dark from the Soil Survey Manual (19) . brown. The B horizon is dark brown, grayish brown, and dark yellowish brown. The consolidated C horizon, at a Alderwood Series depth of 24 to 40 inches, is mostly grayish brown mottled with yellowish brown. Some layers in the C The Alderwood series is made up of moderately well horizon slake in water. In a few areas, there is a drained soils that have a weakly consolidated to strongly thin, gray or grayish-brown A2 horizon. In most areas, consolidated substratum at a depth of 24 to 40 inches. this horizon has been destroyed through logging These soils are on uplands. They formed under conifers, operations. in glacial deposits. Slopes are 0 to 70 percent. The Soils included with this soil in mapping make up no annual precipitation is 35 to 60 inches, most of which more than 30 percent of the total acreage. Some areas is rainfall, between October and May. The mean annual air are up to 3 percent the poorly drained Norma, temperature is about 50 F. The frost-free season is 150 Bellingham, Seattle, Tukwila, and Shalcar soils; some to 200 days. Elevation ranges from 100 to 800 axe up to 5 percent the very gravelly Everett and feet. Meil.ton soils; and some are up to 15 percent Alderwood In a representative profile, the surface layer and soils that have slopes more gentle or steeper than 6 to subsoil are very dark brown, dark-brown, and grayish- 15 percent. Some areas in Newcastle Hills are 25 percent brown gravelly sandy loam about 27 inches thick. The Beausite soils, some northeast of Duvall are as much as substratum is grayish-brown, weakly consolidated to _5 percent Oval'_ soils, and some in the vicinity of Dash strongly consolidated glacial till that extends to a FOint are 10 percent Indianola and Kitsap soils. Also depth of 60 inches and more. included are small areas of Aiderwood soils that have a gravelly loam surface layer and subsoil. Permeability is moderately rapid in the surface layer Arents, Alderwood Material and subsoil and very slow .n the substratum. Roots penetrate easily tc the consolidated substratum where they tend to mat on the surface. Same roots enter the Arents, Alderwood material consists of Alderwood substratum through cracks. Water moves on top of the soils that have been so disturbed through urbanization substratum in winter. Available water capacity is low. that they no longer can be classified with the Alderwood Runoff is slow to medium, and the hazard of erosion ;s series. These soils, however, have many similar moderate. features. The upper part of the soil, to a depth of 20 This soil is used for timber, pasture, berries, and tc 90 inches, is brown to darkbrown gravelly sandy row crops, and for urban development. Capability unit loam. Below this is a grayishbrown, consolidated and IVe-2; woodland group 3d1. impervious'substratum. Slopes generally range from 0 to Alderwood gravelly sandy loam, 0 to 6 percent 1.5 percent. slopes (AgB).--This soil is nearly level and These soils are used for urban development. undulating. It is similar to Alderwood gravelly sandy loam, 6 to 15 percent slopes, but in places its surface layer is 2 to 3 inches thicker. Areas are irregular in Arents, Alderwood material, 0 to 6 percent slopes shape and range from 10 acres to slightly more than 600 (AmB) .--In many areas this soil is level, as a result acres in size. of shaping during construction for urban facilities. Some areas are as much as 15 percent included Areas are rectangular in shape and range from 5 acres to Norma, Bellingham, Tukwila, and Shalcar soils, all of about 400 acres in size. which are poorly drained; and some areas in the vicinity Representative profile of Arents, Alderwood of Enumclaw are as much as 10 percent Buckley soils. material, 0 to 6 percent slopes, in an urban area, 1,300 Runoff is slow, and the erosion hazard is feet west and 350 feet south of the northeast corner of slight. sec. 23, T. 25 N., R. 5 E.: This Alderwood soil is used for timber, pasture, berries, and row crops, and for urban development. 0 to 26 inches, dark-brown (10YR 9/3) gravelly sandy Capability unit IVe-2; woodland group 3d2. loam, pale brown (10YR 6/3) dry; massive; slightly hard, very friable, nonsticky, Alderwood gravelly sandy loam, 15 to 30 percent nonplastic; many roots; medium acid; abrupt, slopes (AgD).--Depth to the substratum in this soil smooth boundary. 23 to 29 inches thick. varies within short distances, but is commonly about 26 to 60 inches, grayish-brown (2.5Y 5/2) weakly 40 inches. Areas are elongated and range from 7 consolidated to strongly consolidated glacial till, to about 250 acres in size. light brownish gray (2.5Y 6/2) dry' common, medium, Soils included with this soil in mapping make prominent mottles of yellowish brown (10YR 5/6) up .no more than 30 percent of the total acreage. Some moist; massive; no roots; medium acid. Many feet areas are up to 25 percent Everett soils that have slopes thick. of 15 to 30 percent, and some areas are up to 2 percent Bellingham, Norma, and Seattle soils, which are in The upper, very friable part of the soil extends to depressions. Some areas, especially on Squak a depth of 20 to 40 inches and ranges from dark grayish Mountain, in Newcastle Hills, and north of Tiger brown to dark yellowish brown. Mountain, are 25 percent Beausite and Ovall soils. Some areas are up to 30 percent included soils that Beausite soils are underlain by sandstone, and Ovall are similar to this soil material, but either soils by andesite. shallower or deeper over the compact substratum; and Runoff is medium, and the erosion hazard is some areas are 5 to 10 percent very gravelly Everett severe. The slippage potential is moderate. soils and sandy Indianola soils. This Alderwood soil is used mostly for timber. Some This Arents, Alderwood soil is moderately well areas on the lower parts of slopes are used for drained. Permeability in the upper, disturbed soil pasture. Capability unit VIe-2; woodland group 3d1. material is moderately rapid to moderately slow, Alderwood and Kitsap soils, very steep (AkF) .-This depending on its compaction during construction. The mapping unit is about 50 percent Alderwood gravelly substratum is very slowly permeable. Roots penetrate to sandy loam and 25 percent Kitsap silt loam. Slopes are and tend to mat on the surface of the consolidated 25 to 70 percent. Distribution of the soils varies substratum. Some roots enter the substratum through greatly within short distances. cracks. Water moves on top of the substratum in winter. About 15 percent of some mapped areas is an Available water capacity is low. Runoff is slow, and included, unnamed, very deep, moderately coarse the erosion hazard is slight. textured soil; and about 10 percent of some areas is This soil is used for urban development. Ca- a very deep, coarse-textured Indianola soil. pability unit IVe-2; woodland group 3d2. Drainage and permeability vary. Runoff is rapid to very rapid, and the erosion hazard ;.s severe to very Lrcent Arents, Alderwood material, 6 to 15 es.i severe. The slippage potential is severe. --- --- —_----- These soils are used for timber. Capability +Ar.C; .--This sox1 has convex slopes. Areas are r.i:c'anqu'T.ar in shape and range from 10 acres to about 950 unit VIIe-l; woodland group oil. a :. ir: size. APPENDIX A Maintenance Standards for Privately Maintained Drainage Facilities Appendix A of 2005 KCSWDM A-1 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TABLE 3.5.2B SCS WESTERN WASHINGTON 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 AB CD 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 85 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 98 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 curve numbers refer to National Engineering 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 numbers. 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 IN KING 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 Earlmont Silt Loam D Riverwash Variable Edgewick C Salal 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 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 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. 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, Soil Interpretation Record, Form #5, September 1988. C9 3.5.2-2 11/92 il- 1/92 ). SECTION 3.2 RUNOFF COMPUTATION AND ANALYSIS METHODS FIGURE 3.2.2.A RAINFALL REGIONS AND REGIONAL SCALE FACTORS ST 1.0/ ST 1.1 ST 1.0 LA 0.8 LA 0.9 LA 1.0 LA 1.2 i IIAKf I SOT Us SNOHOMISH COUNTY ', 'i 00p01YILL� KING COUNTY EH.. i`, / ~�' • �,..�,--..) 4 ri ' \- t I i v:4, - -' - • 0! .:. F. 4...Rv.-u.(0 NDAiiklaili ,___ i, „ . s t d. ii z., ,i,_11._isii, Nr h.,..i.1 III)i if 7 1P. ,77.: 4 : L l i Il • ,_l Mori ; r ,ELLEVUE Bay O ` _ = f PINE90 f. rJ.46E 11111111111111101111161111111. 4/ 1 Hmnno G9 '- ,lk.t, .,„4. i SEATTLE .1 C .3 1 \ ., ',OH uP.6RE,SaT,OIN,+-9N000ALMIE•.\!S`,, r POIN • l,p::: h•itriK'l T.'7,lle:‘-,-.1.k-I1 (J f'I `f. PP '.t. _' 509 900 `° X169 0 __---'''• /_,..:,k M.,) T KR '*PT' 1 i . I(EPR6TOH � LANDSBURG 167 i 515 /j •, v OCEOA q '- Q r-+ ; ,s • Y �Ur \ 1 ]11 16 T i T.11 ; , � Q g:d ',Li-LI Ij `� y1T .M IAH°"'' $ulUi� ./ 1. 516 !‘ L.) .., .11 ,4 ..... 7 a ST 1.1 Y KAtvtA,4, 0) , • 6i [ J1 1 i �L .• n //LL`` U Ili I ►A buNG COUNTY , PIERCE COUNTY I 1. ST 1.0 65 4/1 ST 1.0/ ri fei i 0 i i iliii,,, Rainfall Regions and LA 0.8 .�Regional Scale Factors LA 0.9 �' 0 LA 1.0A 1.2 I____; Incorporated Areaj ._c=7 River/Lakep Major Roadp 0 1/24/2005 2005 Surface Water Design Manual 3-22 J-_,J 6.4.1 WETPONDS —BASIC AND LARGE—METHODS OF ANALYSIS FIGURE 6.4.1.A PRECIPITATION FOR MEAN ANNUAL STORM IN INCHES(FEET) ST 1.0/ LA 1.2 ST 1.1 • ST 1.0 LA 0.8 LA. 0.9 ;'°`„1„0,„<,U,... �a • >--...,1, .Ino COUNTY • tT -.)71r r � ,11' -- •-'r 1 „I's.4, ' , d r r 1 -'�,,, j”' -- i i..,.v it _.�r,,S i� 7-n-i ` -.. t \ 5 320, — —`2 111‘ 44111&111 1 4y.„ , rt jøt :oz ,�WI" _� FIlM.. '40:,�ELLC VL AVO ,. , ... I y�11J�l i, ..rine" „,.-...”, SjATHE 1110'1111\iii, 99� 16. ' ' r,, roar .. \`�.: .t't.'(,) i ! tik �syuv , ). t soe itSjo,„ , Et!t0 1/4\ Itry.!'. Tit jr% ,;, › eut4id 1,75031 j.'....._ ._.., \ Niii, _ . ..4. 1 rot ....,.. , . ,..1...„..04 ,„ „, ri ' 4 .•' . V '' N * CI 99 ! .,, -All ,.l 1, 0.54" 9l�s i 11= n °'t!► (0.045') :� A 64 i .IMO eoUNTT , COCCI COUNTY 0.47" iz (0.039') i .. I , 1::::i Incorporated Area 1- �'-" ",. ..cam River/Lake 0.47" 1' — Major Road (0.039') 0.52" 16.�� 0.65" NOTE:Areas east of the eastemmost isopluvial should use 0.65 (0.043') 0.56" . inches unless rainfall data is available for the location of interest (0.054') (0.047') 24 The mean annual storm is a conceptual storm found by dividing the annual precipitation by the total number of storm events per year result,generates large amounts of runoff. For this application,till soil types include Buckley and bedrock soils, and alluvial and outwash soils that have a seasonally high water table or are underlain at a shallow depth(less than 5 feet)by glacial till. U.S. Soil Conservation Service(SCS)hydrologic soil groups that are classified as till soils include a few B. most C,and all D soils. See Chapter 3 for classification of specific SCS soil types. 2005 Surface Water Design Manual 1/24/2005 6-71 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL FIGURE 3.S.1C 2-YEAR 24-HOUR ISOPLUVIALS - -- ,-,ir :.y - ,- '.... ..1 '_. - --- ---..-, . ..,.--.,-_-- 1ltg A0 ..,z, : ,p4:3!...4tly . imalkflis it /4 • "Mai ph, . ‘, 1 toliy.4-Ai ,:\ . 70 - .1b0-11, VOA'autimill ,,....10k i, ,2-ditsza. 4--r4( Airy. A 1-.47-, \ ' 64° • •• .,.. ._ Q IA,.ft wil �: \ A4.. �1 V O) & ‘, .44,4s, . 014 ..._ ( -'-NHAF.0.4 Ai "-".10.40M1 i ' ri Ncier'iit ---"AsEirwinie 0,4" / • 'i '''' \..iglibi..,11. , li , 1' '1 i fir �.,: „j�r ,sera 4o . .....0. 11"/ 71real);: "-r---...."-MVA;02;ZU--! -, .'•; ligairisi . ',I\ 1 fer 1„orgi " ivi. 04 .1, ii , iw 4 -lit\-, _ ,)- I -ilk% I at, ,..4 r• - "ill " ikNit‘ik do. - .101 - \N\,:, / . , . se 4 At -- -f_.‘,41.tilk VAIL , --, I `t 7 . -- Rail i\`.- IL .1-011k.A , - k7% .ar AV: '_ 411 �ltz,, a1 iii?I h,• 4k. 1 • I*�w�i tsw, . iii �� . iss _. N8 • ' , . .= - -\ _ r . : 4 I. i 'INNEINFT - -- 4 iiji 6•1111/ me lk, litN - - - _ -, N1 I/I ' il.rs' 111 riallplai . fi Iv 441 °1•43‘ /- 1 I n. _ .,,. imploini . .4 1 ,,, tiv v: . , yawn dr....117- ov.....dg 4= ....„... /,) . 'I k. , 4,133.1,.. . I:. 1§bffifellit.A•MIAMIHr. 41111 d •'' _ ,_ ii i -e'r:"-* inIMIEwmfoloritiggi . .'x'041110 - /7 ti-f-- roilid \I"NIMEW • i 1'41 ,,-, - 1:__( AtAiiiipmi ,111h74 _ ` � jT4Mr- ' ink 6.7\ iftettod lir weft, 001. .4- , II' if i 'imeg ' !-•' ---,,,,,,,,enit 1-, . , , ' ,. 01 ‘ \ Al: *41 2-YEAR 24-HOUR PRECIPITATION , '�,j"� Jiro �� , ,.3.4�' ISOPLUVIALS OF 2-YEAR 24-HOUR rt►' "gr - .. 35 TOTAL PRECIPITATION IN INCHES 11 _ 0 1 2 3 4 5 6 7 B Mll.sAli I i N .. 1: 300,000 I 3.5.1-8 �' 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL FIGURE 3.S.1D S-YEAR 24-HOUR ISOPLUVIALS "t--• ..4111_740, - - - - *Mt1 1.8 •! ��0.__J 0 _ _ _ .: � tsaf l kwit t 2.1 / - v..-----11 -w„ .w.,,,..., /All 22 dailar• ��eriI� 411111,41 liii44 # 440410 aw► �� loi lii Lik4-01, ,, 1. < til �� w�� I l i , - ,,. 7\11R116, I/ i' ,. 3 �.liii. .„1,......,,,,44., _ • , ,,,,,ir-4.15,! ...iwWiraiihimpoto."- -`;Ar 1 \ `,, lid.TILE T VVIR : tic,„ 4,4„..441R,,,,,assim,_ ......... .,..,-,-----idoww..0. 4:<‘, , - , . 1* S,-, Ili, '� - gp..... , j4, , -74. vg '. --:i.,,, ,‘ 1 it\N, 11 : ,— - . '' .-.. . . . ...,. , ... ,,, t? - rI % k . glaillTO\ t& -- 41, :‘, _ cow-- != i = illi! i• • • k • . C$11 irr t 41;;;;Wift8t. _ 1 \11111 ` h_ 1,! ;silk • , p4 , . ,%.,i; ‘,..„ ,.. , . \ . 1. -dr..• A v. li li 1 ~ • :• , .I � � _ __.\ \ orp 14 110111 - ,iit � mi; r; —4.,. , ter. 47, } - , rhe , 41111 _ lici., ._...,w.. ..iit. .... ... lit •st• ' i r:( i "'• / ""P: 1 IN illi ' i ,4 ;41Poriliii ,, , , ; �,'\.. _,...... .• 1� 1111 .„ c,... . lip ii ....., ( ., ki „. r i, co-- NI%' \. N---.:''*...:10-- I eprik Arai , ati --., / id, t, ,ifire-4. fr s... I _.__., . Intl ., 'Ifr, oiL„ 4 li I N\ i . : ,;(1.- . i • - ' s.s,. gliggi/ ;." ,. ' . il ' 4,‘ I, _I i IF. .. 41-‘ ji; 44. ''' • lir a - \ 5-YEAR 24-HOUR PRECIPITATION 1„�► .v- i .4 ISOPLUVIALS OF 5-YEAR 24-HOUR h • w iltItI IU TOTAL PRECIPITATION IN INCHES (V g, - i I t- " - ' 4r 46..44y.--- - ^ .• 0 1 2 3 4 5 6 7 8 Mlles • t F 1; 300,000 3.5.1-9 `_L' r2F7 1,o KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL FIGURE 3.5.1E 10-YEAR 24-HOUR ISOPLUVIALS -4 'Ali.' i .! . • -.,----...\ aili : . t - . • • Lamm If iirA AI*. MI% 24 I -: FlIgrai 001 Ai Ara 0 • ; 25 .; 4110Piria rArram. M, , 2.6 / . AEON. 4=1 Pim 1,-„..... . 6.'-' 249 . i imidiiiteio- 23 pi• 014%1117, ow clIPA\ ilk r o .g�� e i \ �\ ,- , ..�.�,.rlr- , ^) pm g�% Iilimen-a.. . �1\.,... , 46 i, 29 '\1f ..�, l _ _.lal� iir - c..= .._..... , w __ ... ._ ,, _lir ,.... _g,„„,, ao -- --‘ .. 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TAMA* Itligfinl --,, .. is ' .7:-.---- ..'.12 17 IL-2 Irl MO/AillwAlehi - "II 1 i .` — r A V fa"rair A-_,r. i ps re- r 0 ill tritiM Na' - t ,: t ,I ris -----400.ki Ili .. , 1,1 ,=imu v 4,, AaT , i, .. , , ..„ N - - -- - "I"L ' ----- - rAffirki ;'' 1 iNC) =1;21NEW111-114 100-YEAR 24-HOUR PRECIPITATION YTAW ' 6.5Or N I�II��R%7• 5.. ----.---ISOPLUVIALS OF 100-YEAR 24-HOUR �• �� I, TOTAL PRECIPITATION IN INCHES (b`�,/ _ ' = J 0 1 2 3 4 5 6 7 8 Mllesr i r,, 3.5.1-13 p` �Q :r, 1: 300,000 1/90 ICICLE CREEK ENGINEERS Geotechnical, Geologic and Environmental Services May 17, 2006 Steve Beck Amberwood LLC 19129 SE 145th Street Renton,Washington 98059 • Report Preliminary Geotechnical Engineering Services Proposed Beclan Place Residential Development King County Tax Lot Nos. 152305- 9065, 152305-9090/9116/9064 Renton, Washington File No. 0641-002 INTRODUCTION This report summarizes Icicle Creek Engineers'(ICE's)preliminary geotechnical engineering services regarding the proposed Beclan Place residential development located northeast of the intersection of NE 2nd Street(SE 132nd Street)and Jericho Avenue NE(144th Avenue SE)in Renton, Washington. The proposed development occupies about.7.1 acres and is comprised of King County Tax Lot Parcel Nos. 152304-9065, 152305-9090/9116/9064. Our services were completed in general accordance with our Proposal dated February 13, 2006 and were authorized in writing by Steve Beck of Amberwood LLC, on March 10,2006. The project site is shown relative to nearby physical features on the Vicinity Map, Figure 1. PROJECT DESCRIPTION Our understanding of the project is based on discussions with Steve Beck of Amberwood LLC,and an untitled schematic site plan provided by Mr. Beck dated February 3, 2006. We understand the conceptual development plan involves subdividing the existing parcels into 32 new lots. Two existing houses on the site that are accessed from NE 2nd Street will remain. Each new lot will be developed as a single-family residence. Improvements will also include paved roads, underground utilities and two stormwater detention ponds. The grading plans have not been finalized at this time. We understand that mass grading(cuts and fills), with exception of the stormwater detention ponds, will be less than about 5 feet. The Beclan Place project site will be accessed by paved roads that extend west from Jericho Avenue SE and north from NE 2nd Street. The proposed lot and road layout,and stormwater detention pond locations are shown on the Site Plan, Figure 2. SCOPE OF SERVICES The purpose of our preliminary geotechnical engineering services was to explore subsurface soil and ground water conditions at the subject property as a basis for developing geotechnical recommendations for planning site development. Specifically our scope of services included: • Complete a geologic reconnaissance of the property to evaluate current site conditions. • Explore subsurface soil and ground water conditions by excavating nine test pits up to 7 feet deep using a rubber-tired backhoe. • 230 NE Juniper Street, Suite 101 • Issaquah, WA 98027-2519 • wws ic,cecree::enqineers.00m • 1.425)427-8187 phone • (425)427-6629 fax Steve Beck Amberwood LLC May 17, 2006 Page 2 • Provide preliminary recommendations for earthwork including stripping and excavation of unsuitable soils, fill compaction and subgrade preparation requirements, and suitability of on-site soils for use in structural fills including an evaluation of the effects of weather and/or construction equipment on the workability of site soils. • Provide preliminary recommendations for foundation support for the proposed structures including allowable bearing pressures, settlement estimates and support of on-grade floor slabs and paved areas. • Provide preliminary recommendations for surface and subsurface drainage systems as appropriate. SITE CONDITIONS GENERAL A geologist from ICE completed a geologic reconnaissance and subsurface explorations at the Beclan Place site on April 5,2006. The following sections summarize our observations of the existing site conditions. SURFACE CONDITIONS As previously mentioned,the approximately 7.1 acre site consists of four tax lots that are situated on the west side of Jericho Avenue SE north of NE 2nd Street. Adjacent properties include residential properties to the north,a residential property and undeveloped property to the west;NE 2nd Street,a residential property and an undeveloped grass-covered lot to the south, and Jericho Avenue SE and residential properties to the east. The site is generally level with a slight overall slope down to the southwest ranging from about Elevation 425 to 415 feet. A single-family house and several out-buildings are present on Tax Lot No. 152305-9064 located in the southeast corner of the site. There is also a single-family house on Tax Lot No. 152305-9116, the northernmost lot along Jericho Avenue SE. The remainder of the site is currently undeveloped. The developed areas are vegetated with lawn,landscape shrubs and occasional trees. The undeveloped areas are vegetated with mature,second-growth conifer and deciduous trees with a dense understory of brush. We observed accumulated surface water in a low area in the northwest portion of the site. The water appeared to be the result of ponding in a localized shallow closed depression following recent rainfall. No other surface water was observed on the site at the time of our geologic reconnaissance. SUBSURFACE CONDITIONS The surficial geology at the site was mapped by the U.S.Geological Survey(USGS-D.R.Mullineaux, "Geologic Map of the Renton Quadrangle,King County,Washington," 1965)as"ground moraine deposits." Ground moraine deposits are described by the USGS as consisting of glacial till that is locally mantled with recessional outwash. Glacial till typically consists of an unsorted mixture of dense to very dense, silt, sand, gravel, cobbles and boulders. Recessional outwash typically consists of medium dense sand with variable amounts of silt and gravel. Subsurface conditions at Beclan Place were explored by excavating nine test pits(TP-1 through TP-9) at the locations shown on Figure 2. The test pits were excavated on April 5,2006 to depths ranging from 5 to 7 feet using a Case 140K rubber-tired backhoe. The test pit locations were selected based on existing site conditions and the proposed development. The test pit excavations were continuously monitored by a geologist from ICE who observed and classified the soils encountered,observed ground water conditions and prepared a detailed log of each test pit. An explanation for the test pit logs is presented in Figure 3. The logs of the test pits are presented in Figures 4 through 8. Icicle Creek Engineers 06110021051706 Steve Beck Amberwood LLC May 17, 2006 Page 3 Our explorations encountered relatively consistent soil conditions across the site and generally consistent with regional mapping by the USGS and our experience in the general area of the site. The test pits encountered relatively uniform soil conditions consisting of about 1 to 1.5 feet of topsoil (loose silty fine sand with gravel and roots),underlain by about 1 to 3.7 feet(average thickness of 2 to 2.5 feet of weathered soil consisting of medium dense silty sand with gravel. The weathered soil was underlain by undisturbed glacial till consisting of dense to very dense silty sand with gravel to the completion depth of the explorations at a depth of 5 to 7 feet. Typically the undisturbed glacial till was encountered at a depth of about 2 to 5 feet below the existing ground surface. The test pits were generally excavated to practical digging refusal using the previously described excavation equipment. Ground water seepage was observed in all of the test pits except Test Pit TP-5,at depths ranging from 2 to 5 feet below the ground surface at the time of our explorations. It is likely that this ground water is perched in the weathered soil where it is in contact with the underlying,less permeable undisturbed glacial till. Perched ground water may be encountered during site grading depending on season,precipitation and other factors. CONCLUSIONS AND RECOMMENDATIONS GENERAL It is our opinion that subsurface conditions at the site are satisfactory for the proposed residential development. Based on the results of our explorations, it appears that the majority of the site soils(medium dense weathered soil and dense to very dense glacial till)will be suitable for support of conventional spread footings. The near-surface soils have sufficient fines(soil particles passing the U.S. Standard No. 200 sieve) content to be moisture-sensitive. These soils will be difficult or impossible to compact when the moisture content is more than a few percent over the optimum moisture content. We recommend that the earthwork portions of the project be completed during the drier summer months to manage earthwork costs. The glacial till,which likely underlies the entire site at a relatively shallow depth,is nearly impermeable and impedes the vertical infiltration of water. Grading and drainage should be planned to reduce the potential for localized ponding of surface water. SITE PREPARATION AND EARTHWORK Temporary erosion control measures such as silt fences,straw bales,and detention facilities should be installed to local standards prior to the start of construction. We recommend that the vegetation and topsoil be stripped and removed from the site and/or stockpiled for use in landscape areas,if appropriate. Tree stumps and roots over 2 inches in diameter should be grubbed and removed from areas where houses, roadways,driveways and utilities will be located. During dry weather conditions, the depth of stripping is expected range from 1 to 2 feet unless excessive disturbance is caused by the clearing operations. Stripping to a greater depth should be expected near grubbed tree stumps or if these operations are done during wet weather. After stripping and grubbing is completed,a representative from ICE should evaluate the exposed ground surface in building, roadway and driveway areas to identify areas that are soft, loose or otherwise unsuitable and to advise the earthwork contractor regarding removal and replacement of unsuitable soils. STRUCTURAL FILL AND FILL PLACEMENT New fill in the building site area on each lot, and roadway and driveway areas should be placed as structural fill. The suitability of soil for use as structural fill will depend on its gradation and moisture content. Icicle Creek Engineers 0641002/051706 Steve Beck Amberwood LLC May 17,2006 Page 4 As the amount of fines increases, soil becomes increasingly more sensitive to small changes in moisture content and adequate compaction becomes more difficult to achieve. The on-site soils contain a sufficient amount of fines to be moisture-sensitive. During dry weather,the on-site soils can be used as structural fill,provided that these materials are conditioned to the proper moisture content for compaction. The on-site soils will not be suitable for use as structural fill during wet weather. On- site soils considered unsuitable for use as structural fill during any weather conditions include the topsoil and soils containing debris,organic contaminants or cobbles greater than 6 inches in diameter. If structural fill must be placed during wet weather, we recommend the use of imported sand and gravel containing less than 5 percent fines by weight relative to the fraction of the material passing the 3/4-inch sieve. The imported sand and gravel should be moisture-conditioned as necessary for proper compaction. Structural fill should be mechanically compacted to a firm,unyielding condition. Structural fill in the building areas should be compacted to at least 95 percent of the maximum dry density(MDD)obtained from ASTM Test Method D 1557. Structural fill in roadway and driveway areas,including utility trench backfill, should also be compacted to at least 95 percent of the MDD. As a guideline,structural fill should be placed in loose lifts not exceeding about 10 inches in thickness. The actual loose lift thickness with depend on the quality of the fill and compaction equipment. Each lift should be conditioned to the proper moisture content and compacted to the specified density. We recommend that a representative from ICE observe structural fill placement and compaction and complete in-place moisture-density tests to evaluate whether adequate compaction is being achieved and advise the contractor of modifications to procedures which may be appropriate for the prevailing conditions. FOUNDATION SUPPORT Houses may be satisfactorily supported on conventional spread footings provided they are constructed in accordance with the recommendations described below. We recommend that foundations be supported on medium dense or denser native soil. Alternatively,the footings may be supported on a pad of structural fill that extends down to medium dense or denser native soils. Where structural fill is placed below footing subgrade elevations,the zone of structural fill should extend laterally beyond the footing edges a horizontal distance at least equal to the thickness of the structural fill in all directions. We recommend that continuous and isolated footings have minimum widths of 16 and 24 inches, respectively. The exterior footings should be a minimum of 18 inches below the adjacent grade. Footings supported as described in the previous paragraph may be designed using an allowable soil bearing value of 2,500 pounds per square foot (psf). This value applies to the sum of all dead and long-term live loads, exclusive of the weight of the footing and backfill above the footing. The allowable bearing pressure may be increased by one-third for total loads including wind or seismic. In preparing footing subgrades, care should be taken to avoid loosening or softening the bearing surface soils,particularly during wet weather. During wet weather,footings should be excavated,formed and poured the same day or be protected by a layer of lean concrete or crushed rock at least 2 inches thick placed on the prepared footing subgrade. The footing subgrades should be observed by a representative from our firm to evaluate whether suitable bearing soils have been exposed and the subgrade has been adequately prepared. We estimate that total settlements of footings,founded as described above,will be less than 1 inch and differential settlements will be less than V2 inch. Settlements are expected to occur rapidly as loads are applied. SLAB SUPPORT The slab-on-grade subgrades should be prepared in accordance with the previously described Site Preparation and Earthwork recommendations. We recommend that the subgrade surface be compacted such Icicle Creek Engineers 0641002/051706 Steve Beck Amberwood LLC May 17,2006 Page 5 that a minimum compaction of 95 percent of the MDD is achieved before placing structural fill or capillary break material. We recommend that a compacted base-course layer consisting of at least 4 inches of gravel containing less than 3 percent fines be placed on the subgrade to provide uniform support and act as a capillary break beneath the slab. A vapor retarder should be placed beneath the slab if moisture control in the slab is critical (i.e., where tile or carpeting is to be glued to the slab). This vapor retarder should consist of polyethylene sheeting. A layer of clean sand not more than 2 inches in thickness may be placed over the polyethylene sheeting. The vapor retarder should be placed immediately below the slab. We estimate that the settlement of floor slabs due to uniform areal loads of 150 psf will be less than%z inch. These settlements are expected to occur rapidly upon load application. UNDERGROUND UTILITY CONSIDERATIONS Excavation Cut Slopes Temporary cuts greater than 4 feet in depth in glacial till may be made at an inclination of 1H:1 V (horizontal:vertical),or flatter. Flatter slopes may be necessary if instability is observed. Some sloughing and raveling of the cut slopes should be expected. Temporary covering, such as heavy plastic sheeting, should be used to protect these slopes during periods of wet weather. Surface water runoff should be prevented from flowing over cut slope faces by using berms,drainage ditches,swales or other appropriate methods. If temporary cut slopes experience excessive sloughing or raveling during construction,it may become necessary to modify the cut slope inclinations to maintain safe working conditions and protect adjacent facilities or structures. Slopes experiencing problems can be flattened or regraded to add intermediate slope benches if poor slope performance is encountered. Alternatively, underground utility trenches can be completed using temporary trench shoring(shored excavations)in lieu of cut slopes. Shored Excavations To construct the underground utilities, it may be necessary to support the temporary excavations to maintain the integrity of the surrounding undisturbed soils, reduce disruption of adjacent areas, as well as to protect the personnel working within the excavations. Because of the diversity of available shoring systems and construction techniques, the design of temporary shoring is most appropriately left up to the contractor. We recommend that the shoring be designed by a licensed professional engineer in Washington,and that the PE-stamped shoring plans and calculations be submitted to the project engineer for review and comment prior to construction. The following paragraphs present recommendations for the types of shoring systems and design parameters that we conclude are appropriate for the subsurface conditions at the site. The majority of the materials within the project area can be retained using conventional trench shoring systems such as trench shields or sheet piles, with lateral restraint. The design of temporary shoring should allow for lateral pressures exerted by the adjacent soil, and surcharge loads due to traffic, construction equipment,and temporary stockpiles adjacent to the excavation,etc. Lateral load resistance can be mobilized through the use of braces, tiebacks, anchor blocks and passive pressures on members that extend below the bottoms of excavations. Temporary shoring utilized to support excavation walls typically uses internal bracing such as aluminum hydraulic shoring or trench shield bracing. Temporary trench shoring with internal bracing can be designed using active soil pressures. We recommend that temporary shoring be designed using a lateral pressure equal to an equivalent fluid density of 35 pounds per cubic foot (pcf), for conditions with a level ground surface adjacent to the excavation. If the Icicle Creek Engineers 06410021051706 Steve Beck Amberwood LLC May 17, 2006 Page 6 ground within 5 feet of the excavation rises at an inclination of 1 H:1 V,the shoring should be designed using an equivalent fluid density of 75 pcf. For adjacent slopes flatter than 1 H:1 V,soil pressures can be interpolated between this range of values. Other conditions should be evaluated on a case-by-case basis. These lateral soil pressure values do not include traffic or construction surcharges that should be added separately, if appropriate. It is typical for shoring to be designed for a traffic influence equal to a uniform lateral pressure of 100 psf acting over a depth of 10 feet below the ground surface. More conservative pressure values should be used if the designer deems them appropriate. These soil pressure recommendations are Based upon the excavation being essentially dewatered;therefore,hydrostatic water pressures are not included. Resistance to lateral loads can be obtained from passive pressures exerted on buried foundation elements and frictional resistance on the base of foundation elements. We recommend using an equivalent fluid pressure value of 350 pcf to estimate passive pressures and a coefficient of friction of 0.4. These values 111 include a factor of safety of 1.5. Temporary cut slopes and shoring must comply with the provisions of Title 296 Washington Administrative Code(WAC),Part N,"Excavation,Trenching and Shoring." We recommend that temporary excavations, including temporary shoring, be made the responsibility of the contractor. The contractor is present at the site continuously and is best able to observe changes in site and soil conditions and monitor the performance of excavations. Trench Backfill Trench backfill should consist of structural fill-quality material. Structural fill materialshould be free of debris, organic contaminants and rock fragments larger than 6 inches. As a guideline, backfill should be placed in lifts of 12 inches or less (loose thickness). Each lift should be compacted prior to placing the subsequent lift. Trench backfill should be compacted in lifts to at least 90 percent of the MDD obtained in general accordance with ASTM Test Method D 1557 more than 2 feet below final subgrade elevation and to at least 95 percent of MDD above this level. During trench backfill placement,a representative from ICE should complete in-place density tests to evaluate if the required compaction is being achieved. STORMWATER DETENTION PONDS We anticipate that the stormwater detention ponds will be excavated into native glacial till. We recommend that the wetter interior side slopes of the detention ponds be no steeper than 3H:1 V. Fill berms,if used,should be constructed with soil containing more than 20 percent fines(such as the onsite weathered soil and glacial till)and compacted to at least 95 percent of the MDD obtained in general accordance with ASTM Test Method D 1557. Fill placed as berms should be keyed into the native ground surface to reduce the potential for seepage through the berm. EROSION CONTROL AND DRAINAGE CONSIDERATIONS The surficial soils on the site have a high potential for erosion on slopes greater than about 20 percent when disturbed by construction activities. Erosion control measures should be implemented prior to the start of site preparation,including proper control of surface water runoff, use of straw bales or appropriate geotextile filters and temporary sedimentation basins. Erosion control measures should comply with City of Renton requirements. Based on conditions encountered in our test pit explorations,it is possible that perched ground water may be encountered temporary excavations or permanent cuts. We anticipate that seepage may be adequately handled by installation of French drains, open ditches and/or pumping as necessary. The grading should be done to avoid concentration of runoff and,or ponding of surface water. We Icicle Creek Engineers 0641002/051706 I Steve Beck Amberwood LLC May 17,2006 Page 7 recommend sloping the ground surface away from structures. Roof downspouts must be tightlined to an approved disposal area. Other surface runoff may be addressed by using swale drains, drainage ditches or other drainage measures. We recommend that perimeter footing drains be installed adjacent to the outside footings of all structures. These drains should consist of a minimum 4-inch diameter perforated smooth-walled pipe surrounded with at least 6 inches of free-draining sand, sand and gravel or pea gravel, with the perforations down and the base of the pipe located at the same elevation as the base of the adjacent footings. The drainage material should be enclosed within a nonwoven geotextile fabric to reduce the potential for fines contamination from the native soil. The perimeter footing drain should be connected to a tightline collection system that discharges away from the developed areas. Roof drains on structures should be connected directly to a tightline collection and disposal system that is separate from the footing drain. Perched ground water observed in the test pits may result in the development of"wet areas"at finished grades. Interceptor drains or French drains installed in selected locations is an effective way to manage perched ground water. The need for and location of these drains should be a field decision at the time of construction. The drain should consist of a trench at least 18 inches wide and 24 inches deep. The depth of the drain will depend on the site conditions and may be deeper(typically to the depth of the undisturbed glacial till). A rigid smooth-walled perforated pipe at least 4 inches in diameter should be placed in the bottom of the trench,surrounded with at least 6 inches washed rock or pea gravel and wrapped with a nonwoven geotextile fabric such as Mirafi 140N. USE OF THIS REPORT We have prepared this report for use by Amberwood LLC. The data and report should be provided to prospective contractors for their bidding or estimating purposes,but our report,conclusions and interpretations should not be construed as a warranty of the subsurface conditions. If there are changes in the grades, locations, configurations or types of the facilities planned, the conclusions and recommendations presented in this report may not be applicable. If design changes are made, we request that we be given the opportunity to review our conclusions and recommendations and to provide a written modification or verification. When the design has been finalized,we recommend that the final design and specifications be reviewed by our firm to see that our recommendations have been interpreted and implemented as intended. There are possible variations in subsurface conditions between the explorations and also with time. A contingency for unexpected conditions should be included in the project budget and schedule. Sufficient monitoring,testing and consultation by our firm should be provided during construction to evaluate whether the conditions encountered are consistent with those indicated by the explorations,to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork and foundation installation activities comply with contract plans and specifications and our recommendations. Within the limitations of scope,schedule and budget,our services have been executed in accordance with generally accepted practices in this area at the time the report was prepared. No warranty or other conditions, express or implied, should be understood. Icicle Creek Engineers 0641002/051706 Steve Beck Amberwood LLC May 17,2006 Page 8 We trust this report meets your present needs. Please call if you have any questions concerning this report. 1 '4'.. R• . 7 /.1F. , Yours very truly, ,. ...o w.�41i,c; Icicle Creek Engineers, Inc. 'b�;, ; ii o;� /- ,, e:,,I:!iL'' l ,e,„,Jarze„ er ..r 1, ,0 pr401g?y. r) 7.31 fU < Vil0/0,6 / A74, S,R-G/S*1141-` C "Sp-' Mary S. 'utherford,P.E. iO N A I �` Principal Geotechnical Engineer EXPIRES r, a(.7..g.(2--c2. Document ID: 0641002.rep Three copies submitted Attachments: Figure 1—Vicinity Map Figure 2—Site Plan Figure 3—Explanation for Test Pit Logs Figures 4 through 8—Test Pit Logs Icicle Creek Engineers 0641002/051706 o `� � � ;I. I i G+ f �:.-iJ\•rte_. 0 8`Rr11a Qrave Pds •y• '• 1"- • ;— "`\.v l?' •, • f d l e2 • Park Ka Yd \ 1 erg .h •\. ' 'IN ` ,, •. ,,,,,awN.,:,•,..,..,-- ,, . ,.....__. • -,,,••• _— ._..7 \_ • ____ .---,----,,..::\s'N\'\'‘' ,,,11 I\\,:4\16. , • • . \ ( ' <I\ f\i,?`•j I% 4 ti • m1311110i ' 1,\`;'..\ '. '\•..S 'w a i\\:. •,e y r* � �. .• L` -` \\ to `\\� ....,,S ,MOMIlli1 � v 5. • � t•• .e N. 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Pnvate Road —� — — -' — — — r.-� \ • • 1 26 25 —q4 23 22�` _�21 20 Ii \` ��h-^` I 1-•430, \ / ` \\ I\` . / TP-6 I \ 1 1g - I w I \ I fli • ` co �� TP-9 1� c ,. c 1 1 TPi ^� I > Ir----1$1., 1 i 1 / \ "ERZ\ \ • 1 ,�� v �N,� '.,i / �• `_ 10 I g 8 7 6 `1 5�--� 3 `\\\I I I i 4, I ^-11'PA...".—��i; \\• Ins I 12 _.. I I TP-5 �, I TP-2 TP-1\\ 1 I / .. 13 14 /\15 M! 17 18Ili L1—�\ I I N. I I \\ J16 1 I4 t /• l I I 1 415 SE 132nd Street G 0 100 200 ,N ismimmmimami Approximate Scale in Feet 0 0 z a.) Icicle Creek Engineers Site Plan - Figure 2 CLIENT Amberwood LLC PROJECT NAME Beclan Place PROJECT NUMBER 0641-002 PROJECT LOCATION 144th Avenue SE and SE 132nd Street UNIFIED SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS SYMBOLS TYPICAL DESCRIPTIONS CLEAN GRAVELS GW VI_ITTLEOENO FIINNESLS,GRAVEL-SAND MIXTURES, MORE THAN 50%OF (LITTLE OR NO FINES) GP POORLY GRADED GRAVELS,GRAVEL-SAND MIXTURES, Soil Particle Size Definitions COARSE FRACTION UTILE OR NO FINES RETAINED ON NO.4 GRAVELS WITH GM SILTY GRAVELS.GRAVEL-SAND-SILT MIXTURES Component Size Range COARSE SIEVE FINES GRAINED SOILS (APPRECIABLE AMOUNT OF FINES) GC CLAYEY GRAVELS,GRAVEL.SAND-CLAY MIXTURES Boulders Coarser than 12 inch MORE THAN 50%OF $W WELL-GRADED SANDS.UTILE OR NO FINES Cobbles 3 inch to 12 inch MATERIAL IS CLEAN SANDS LARGER THAN NO. (LITTLE OR NO FINES) Gravel 3 inch to No.4(4.78 mm) 200 SIEVE SIZE MORE THAN 50%OF SP POORLY GRADED SANDS.UTILE OR NO FINES Coarse 3 inch to 3/4 inch COARSE FRACTION PASSING Na 4 SIEVE SANDS WITH SM SILTY SANDS,SAND.SILT MXTURES Fine 3I4 inch to No.4(4.78 mm) FINES (APPRECIABLE SC CLAYEY SANDS,SAND•CLAY MX7URES Sand No.4(4.78 mm)to No.200 AMOUNT OF FINES) (0.074mm) INORGANIC SILTS AND VERY FINE SANDS,ROCK FLOUR, Coarse No.4(4.78 mm)to No.10 ML SILTY OR CLAYEY FINE SANDS OR CLAYEY SILTS WITH SUGHT PLASTICITY (2.0 mm) SILTS AND LIQUID LIMIT LESS INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY, Medium No.10(2.0 mm)to No.40 FINE GRAINED CLAYS THAN 50 CL GRAVELLY CLAYS.SANDY CLAYS.SILTY CLAYS.LEAN SOILS CLAYS (0.42 mm) OL ORPGusnANIC aTSILYTS AND ORGANIC SILTY CLAYS OF LOW Fine No.40(0.42 mm)to No.200 MORE THAN 50%OF MH IN SILTS.MCACEOUS OR DIATOMACEOUS FINE (0.074 mm MATERIAL IS SANDY OR SILTY SOILS.ELASTIC SILTS ) SMALLER THAN 200 SIEVE SIZE NO. SILTS AND LIQUID LIMIT Sift and Clay Finer than No.200(0.074 mm) CLAYS GREATER THAN 50 CH INORGANIC CLAYS OF HIGH PLASTICITY OH ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY, Moisture Content ORGANIC SILTS HIGHLY ORGANIC SOILS PT PEAT.HUMUS.SWAMP SOILS WITH HIGH ORGANIC CONTENTS Dry Absence of moisture NOTES1 Dual symbols are used to indicate gravels or sand with 5-12%fines and soils with fines classifying as CL-ML. Moist Damp but no visible water 2 Symbols separated by a dash indicate borderline soil classifications. 3 I he lines separating soil types on the logs represents approximate boundaries only.The actual boundaries Wet Visible water may vary or be graiival. 4 Soil Classification based on visual classification of soil is based on ASTM 02488-90,g 5 Soil Classification using laboratory tests is based on ASTM D2487-90. 6 Description of soil density or consistency is based on interpretation of blow count data and/or test data. Sampler and Other Symbol Descriptions Relative Consistency ® Location of Grab Sample Fine-Grained Soils V Approximate depth of perched water or ground water Very Soft Easily penetrated several inches by fist Soft Easily penetrated several inches by thumb • Asphalt Medium Stiff Penetrated by thumb with effort Stiff Indented by thumb with effort Very Stiff Indented by thumbnail Hard Indented with difficulty with thumbnail NOTE: The depths on the test pit logs are shown in 0.1 foot increments, however these depths are based on approximate measurements across the length of the test pit and should be aconsidered accurate to 0.5 foot.The depths are relative to the adjacent ground surface. 1- o 0 ai 0 2 w V E'. 0 N O _O K H a I-- Cr) w F- ▪ Icicle Creek Engineers Explanation For Test Pit Logs - Figure 3 Test Pit TP-1 CLIENT Amberwood LLC PROJECT NAME Beclan Place PROJECT NUMBER 0641-002 PROJECT LOCATION 144th Avenue SE and SE 132nd Street DATE EXCAVATED 4/5/06 TOTAL DEPTH 6.5 ft GROUND ELEVATION - LOGGED BY BES EXCAVATION CONTRACTOR Amberwood LLC GROUND WATER 4.0 ft .2 CHECKED BY MSR EXCAVATION EQUIPMENT Case 140K rubber-tire backhoe NOTES uJ 2 0 d J >- co =O DO �w I- I w?: • MATERIAL DESCRIPTION Q O OcciIII REMARKS C �cn 2z `° 0 U 0 Dark brown silty fine SAND with gravel and fine roots(loose,moist) (topsoil) '-`',I- SM 1. Brown silty fine SAND with occasional gravel (medium dense to dense,moist to ,_-y - - wet) (weathered glacial till) --- '-' - _ =a-_ SM )S-1 3.5 ,-4= _ _ Light brown silty fine to medium SAND with gravel(dense to very dense,rh3ist) f_-=°_^ 5 (glacial till) XS-2 H7.-- SM e7._-7,7.7. 6.5 -pz.; Test pit completed at 6.5 feet on 4/5/06 Slow ground water seepage observed at 4 feet Disturbed soil sample obtained at 3 and 5 feet Test Pit TP-2 CLIENT Amberwood LLC PROJECT NAME Beclan Place PROJECT NUMBER 0641-002 PROJECT LOCATION 144th Avenue SE and SE 132nd Street - DATE EXCAVATED 4/5/06 TOTAL DEPTH 7.0 ft GROUND ELEVATION - LOGGED BY BES EXCAVATION CONTRACTOR Amberwood LLC GROUND WATER 2.0 ft .SZ CHECKED BY MSR EXCAVATION EQUIPMENT Case 140K rubber-tire backhoe NOTES w co H V d J >- i- i- MATERIAL DESCRIPTION a m w m w o O inx J REMARKS 0 -cp Zz `° 0 0 Dark brown silty fine SAND with fine roots(loose,moist) (topsoil) - -t.5 SM o_ _ Brown silty SAND with gravel(medium dense,wet) (weathered glacial till).V ,--- E N o - e'_ SM XIS-1 o_ 4.0 - ,- 5 Light brown silty SAND with gravel(dense to very dense,moist) (glacial tit) f - `_, 0 -o - - -.- - - SM XS-2 -, 7.0 0_ Test pit completed at 7.0 feet on 4/5/06 8 Moderate ground water seepage observed at 2 feet 0 Disturbed soil sample obtained at 3 and 6 feet F 0 Icicle Creek Engineers Test Pit Logs - Figure 4 Test Pit TP-3 CLIENT Amberwood LLC PROJECT NAME Beclan Place PROJECT NUMBER 0641-002 PROJECT LOCATION 144th Avenue SE and SE 132nd Street DATE EXCAVATED 4/5/06 TOTAL DEPTH 7.0 ft GROUND ELEVATION - LOGGED BY BES EXCAVATION CONTRACTOR Amberwood LLC GROUND WATER 3.0 ft CHECKED BY MSR EXCAVATION EQUIPMENT Case 140K rubber-tire backhoe NOTES w a I CJ -' y i_ w MATERIAL DESCRIPTION m w m 1-0- 1.- r, w� p Q� �� g i REMARKS 6 0crn 2z Q 0 J Dark brown silty fine SAND with gravel and fine roots(loose,moist) (topsoil) -- 1.5 - t SM ;, _ _ Brown silty SAND with gravel(medium dense to dense,moist to wet) (weathered ,-Y -- glacial till) __ y c SM XS-1 4.0 P:_-_.--.. 5 Light brown silty SAND with gravel(dense to very dense,moist) (glacial till) r1±7-7.7-7 XS-2 ,t_-P2 , _47.: SM .v Test pit completed at 7.0 feet on 4/5/06 Moderate ground water seepage observed at 3 feet Disturbed soil sample obtained at 3 and 5 feet Test Pit TP-4 CLIENT Amberwood LLC PROJECT NAME Beclan Place PROJECT NUMBER 0641-002 PROJECT LOCATION 144th Avenue SE and SE 132nd Street DATE EXCAVATED 4/5/06 TOTAL DEPTH 5.0 ft GROUND ELEVATION - LOGGED BY BES EXCAVATION CONTRACTOR Amberwood LLC GROUND WATER 2.0 ft V CHECKED BY MSR EXCAVATION EQUIPMENT Case 140K rubber-tire backhoe NOTES w = U fl d CL MATERIAL DESCRIPTION i 0 R m m w o g f REMARKS o 0 � ') az 5 LI Dark brown silty SAND with occasional gravel and fine roots(loose, moist) (topsoil):11ii`_-' 1.5 -ckJ SM e_ _ Brown to light brown silty SAND with gravel(medium dense to very dense,'oist to r-_.---__-' N wet) (glacial till) 0 SM 0 5 5.0 51-:-,•-,_ cam---1- Test pit completed at 5.0 feet on 4/5/06 �S Slow ground water seepage observed at 2 feet Disturbed soil sample obtained at 5 feet 2 0 N O O O so O C Icicle Creek Engineers Test Pit Logs - Figure 5 Test Pit TP-5 CLIENT Amberwood LLC PROJECT NAME Beclan Place PROJECT NUMBER 0641-002 PROJECT LOCATION 144th Avenue SE and SE 132nd Street DATE EXCAVATED 4/5/06 TOTAL DEPTH 6.5 ft GROUND ELEVATION - LOGGED BY BES EXCAVATION CONTRACTOR Amberwood LLC GROUND WATER None observed CHECKED BY MSR EXCAVATION EQUIPMENT Case 140K rubber-tire backhoe NOTES w O 01 o MATERIAL DESCRIPTION Q O2 J2 1— REMARKS aOi z 0 C g Dark brown silty SAND with gravel and fine roots(loose,moist) (topsoil) - -1.3 =''—' SM Brown to light brown silty SAND with gravel(medium dense to very dense, moist) (glacial till) -�- SM K uS 1 5 6.5 z-=o Test pit completed at 6.5 feet on 4/5/06 No ground water observed Disturbed soil sample obtained at 4 feet Test Pit TP-6 CLIENT Amberwood LLC PROJECT NAME Beclan Place PROJECT NUMBER 0641-002 PROJECT LOCATION 144th Avenue SE and SE 132nd Street DATE EXCAVATED 4/5/06 TOTAL DEPTH 6.5 ft GROUND ELEVATION - LOGGED BY BES EXCAVATION CONTRACTOR Amberwood LLC GROUND WATER 2.5 ft SZ CHECKED BY MSR EXCAVATION EQUIPMENT Case 140K rubber-tire backhoe NOTES w CL o- o i-- -- MATERIAL DESCRIPTION a m w m w - >- a-Z Co REMARKS 0 0 5 Dark brown silty SAND with gravel and fine roots(loose, moist) (topsoil) r -1.3 SM Brown to light brown SAND with silt and gravel(medium dense to very dense, moist to wet) (glacial till) 0 C7 ° :b c... SP- o 5 SM �/ XS-1 t - 6.5 Test pit completed at 6.5 feet on 4/5/06 I J V Very slow ground water seepage observed at 2.5 feet Disturbed soil sample obtained at 5 feet C Icicle Creek Engineers Test Pit Logs - Figure 6 Test Pit TP-7 CLIENT Amberwood LLC PROJECT NAME Beclan Place PROJECT NUMBER 0641-002 PROJECT LOCATION 144th Avenue SE and SE 132nd Street DATE EXCAVATED 4/5/06 TOTAL DEPTH 6.0 ft GROUND ELEVATION - LOGGED BY BES EXCAVATION CONTRACTOR Amberwood LLC GROUND WATER 3.0 ft V CHECKED BY MSR EXCAVATION EQUIPMENT Case 140K rubber-tire backhoe NOTES w I U a� >- o_ H ao 0m Wm w CL MATERIAL DESCRIPTION Q p O 2 _j 2 REMARKS (3 c0� 2z °° 0 Dark brown silty SAND with gravel and fine roots(loose,moist) (topsoil) - -1.3 ='—' S M - Brown to light brown silty SAND with gravel(medium dense to dense, moist to wet)r-e - (glacial till) _,_•-.- Q - _ SM XS-1 5 ---T=- _ _6.0 : � Test pit completed at 6.0 feet on 4/5/06 Slow ground water seepage observed at 3 feet Disturbed soil sample obtained at 4 feet Test Pit TP-8 CLIENT Amberwood LLC PROJECT NAME Beclan Place PROJECT NUMBER 0641-002 PROJECT LOCATION 144th Avenue SE and SE 132nd Street DATE EXCAVATED 4/5/06 TOTAL DEPTH 6.0 ft GROUND ELEVATION - LOGGED BY BES EXCAVATION CONTRACTOR Amberwood LLC GROUND WATER 2.0 ft V CHECKED BY MSR EXCAVATION EQUIPMENT Case 140K rubber-tire backhoe NOTES w i 0 J o 1co — co CL MATERIAL DESCRIPTION a rn m w m w 0 �� F REMARKS 0 (3 ern QZ I N Dark brown silty SAND with gravel and fine roots(loose,moist) (topsoil) P.,- ,L SM - -1.3 a _ Brown to light brown silty SAND with gravel(medium dense to very denseoist to , ,n - - o wet) (glacial till) Lo o - o .. ,_SSM 1H60 Test pit completed at 6.0 feet on 4;5/06 -- a. Slow ground water seepage observed at 2 feet Disturbed soil sample obtained at 5 feet 0 K L Icicle Creek Engineers Test Pit Logs - Figure 7 Test Pit TP-9 CLIENT Amberwood LLC PROJECT NAME Beclan Place PROJECT NUMBER 0641-002 PROJECT LOCATION 144th Avenue SE and SE 132nd Street DATE EXCAVATED 4/5/06 TOTAL DEPTH 6.0 ft GROUND ELEVATION - LOGGED BY BES EXCAVATION CONTRACTOR Amberwood LLC GROUND WATER 5.0 ft V CHECKED BY MSR EXCAVATION EQUIPMENT Case 140K rubber-tire backhoe NOTES w a 2 U 0 J >-0_ I- a Z MATERIAL DESCRIPTION a Op m w m Cl) a-- O z m REMARKS 0 Dark brown silty SAND with gravel and fine roots(loose, moist) (topsoil) -1.3 _ SM Brown to light brown silty SAND with gravel(medium dense to dense,moist to wet) (glacial till) =- TT A.: - =o;= SM 5 = XIS-1 6.0 _ Test pit completed at 6.0 feet on 4/5/06 Slow ground water seepage observed at 5 feet Disturbed soil sample obtained at 4.5 feet O 0 N N U Q J W U_ a N O O O O O Icicle Creek Engineers Test Pit Logs - Figure 8 i itri 111 7 6 :. 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' • ... • c . _ () 3—a:1 7---7(-)600 , --e _ i ' '. "' firs• OA 1 r s LANDSLIDE HAZARD _ AREAS rernnkal$ervecs L� Moderato King County Hazard l„ ')a..1-°;12.°:".''' I Hipp - -- City Limits " (I Very Hi Associated Earth Sciences, Inc . SA ® AO 't rali Technical Memorandum Date: August 15, 2012 To: Corey Watson Project Name: Beclan Place Quadrant Corporation From: Matt Miller, P.E. Project No: EE120195A Subject: Detention Pond Liner At your request AESI observed the excavation of one exploration pit within the footprint of the proposed detention pond at Beclan Place. At this time the pond excavation has started and there is about 6 feet left to get to the bottom elevation of the pond and the sidewalls are exposed for visual observation. RPD Construction excavated a pit to an elevation of about 2 feet below the bottom elevation of the pond. The conditions encountered within the pit are dense to very dense glacial till for the full depth of the excavation. These conditions are similar to the sidewalls of the pond at this time. Based upon our observations it appears that the pond will be excavated entirely into dense glacial till. Glacial till is known to have minimal to negligible capability for infiltration. Therefore, it is our opinion,based upon conditions observed, a liner will not be needed. ',,EW A. li t,'S „,, 08i-A <',,,, ie VA 2 I. 4 �w F A , '`G/ST�� C4�� it SS/C)S e,l.0 i(' 911 FIFTH AVENUE • SUITE 100 • KIRKLAND, WA 98033 • P:425/827-7701 • F:425/827-5424 • AlderNW March 12, 2007 Project No. 61506 Mr. Steve Beck Amberwood LLC 19129 SE 145th Street Renton, Washington 98056 Subject: Wetland Evaluation/Habitat Study Beclan Place Jericho Avenue NE at NE 2°d Street Renton,Washington Parcel#"s1523059065, 1523059090 and 1523059064 Dear Mr. Beck: As requested, we have conducted a wetland evaluation for the property located on the northwest corner of the intersection of NE 2°d Street and Jericho Avenue, in the City of Renton. The location of the subject parcel is shown on the attached Vicinity Map (Figure 1). The purpose of our work was to identify the limits of the wetland areas on and immediately adjacent to the subject property. In conducting our site wetland evaluation, we followed the general procedures for the routine on-site methodology as outlined in the Washington State Wetlands Identification and Delineation Manual (March 1997). This procedure involves analysis of vegetation patterns, soil conditions, and near-surface hydrology in making a determination of wetland conditions. Our scope of work included site visits in June, 2006 to complete the wetland evaluation and flag the limits of the site wetland. The flagged wetland points have been surveyed and plotted on project maps as shown on project design plans by Schweikl and Associates,and on the Site Map(Figure 2). WETLAND EVALUATION PROCEDURES For the purpose of this study, we used the wetland definition adopted by the Environmental Protection Agency(EPA) and the Army Corps of Engineers(COE)for administering Section 404 of the Clean Water Act. According to this definition, wetlands are: 'Mose areas that are inundated or saturated by surface water or groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include •� swamps, marshes, bogs, and similar areas." (33 CFR 323) In Washington State, the Shoreline Management Act and Growth Management Act have amended this definition to exclude some wetland situations by adding the following sentences to the wetland definition: 518 North 59th Street, Seattle, Washington 98103• Phone (206)783-1036 email aldernw@comcast.net Mr. Steve Beck March 12,2007 Wetlands do not include those artificial wetlands intentionally created from non-wetland sites, including but not limited to, irrigation and drainage ditches, grass-lined swales, canals, detention facilities, wastewater treatment facilities, farm ponds, and landscape amenities, or those wetlands created after July 1, 1990, that were intentionally created as a result of the construction of a road, street or Highway. Wetlands may include those artificial wetlands intentionally created from non- wetland areas to mitigate the conversion of wetlands. Delineation procedures are based on diagnostic environmental indicators of wetland vegetation, wetland soils, and wetland hydrology. These procedures, outlined in the Washington State Wetlands Identification and Delineation Manual (March 1997) are commonly known as a Triple Parameter Method. By definition, an area is designated as wetland when there are positive indicators for all three parameters. A listing of plant species has been developed for use in the methodology for delineating wetland areas. This listing assigns plant species to one of five indicator status categories ranging from Obligate wetland species, which almost always occur in wetlands, to Upland species, which rarely occur in wetlands. Under normal conditions, hydrophytic vegetation is determined to be present if more than 50 percent of the dominant species are in the Obligate (OBL), Facultative Wetland(FACW),or Facultative(FAC)indicator categories. Diagnostic indicators of hydric soils are related to soil saturation, which leads to anaerobic conditions in the soil. Under these conditions, decomposition of organic material is inhibited and soil minerals are reduced, creating characteristic soil colors that can be quantified eor by comparison with Munsell Soil Color Charts. A chroma of one or less in unmottled soils or a chroma of two or less in mottled soils generally indicates a hydric soil. In addition, soils that are saturated during the growing season satisfy a criterion for hydric soils. We used a hand auger and or shovel to collect soil samples from depths of 8 to 18 inches, or below the A horizon. Wetland hydrology is defined as inundated or saturated soil conditions for at least 14 consecutive days during growing season. If no water is present at the time of evaluation, other indicators mayinclude topographic lownts the or channels, flood debris, complete absence of vegetation, or presence of hydric soils. olp GENERAL SITE CONDITIONS The subject property is made up of three parcels with a combined area of approximately 7.1 acres. It is located on the west side of Jericho Avenue NE (144t2 Avenue SE), north of NE 2"d Street (SE 132nd Street) in the City of Renton,as illustrated on Figure 1. Adjacent properties to the north and on the east side of Jericho Avenue NE are occupied byexistingsingle-family residences. Properties to the west and south are under development, P or building development applications are pending. Topographically, the property is nearly flat with a slight gradient sloping down from northwest to southwest across the site. Elevations range from about elev. 430 on the northeast property corner to about elev.410 at the southwest property corner. Soils across the property and on much of the surrounding area are mapped as Alderwood gravelly sandy loam (Soil Survey of King County, Washington, U.S. Soil Conservation Service, 1973). The Aldenvood series is made up of moderately well-drained soils that have a weakly to strongly consolidated substratum at depths of between 24 and 40 inches. The National Technical Committee for Hydric Soils does not list the Alderwood series as a hydric soil although wetland conditions are common in depressional areas within Alderwood soil units. The western section of the site is occupied by a mixed conifer-deciduous forest stand. Red alder(Alnus rubra) black cottonwood (Populus balsamifera), big leaf maple(Acer macrophyllum), western red cedar(Thuja plicata), western Project No. 61506 Page No. 2 Mr. Steve Beck March 12,2007 hemlock (Tsuga heterophylla) and Douglas fir(Pseudotsuga menziesii) are the predominant tree species on the site. Salmonberry(Rubus spectabilis),and Himalayan blackberry(Rubus discolor)are the common shrub species. Until recently there had been two houses on the eastern section of the property. The houses were torn down and removed sometime after early April, 2006. Vegetation on this section includes the lawn and landscaping around the homesites. There are scattered trees including several domestic fruit trees. There are tall black cottonwood trees in a line along NE Second Street. WETLAND AREA We have identified the limits of a wetland on the northwest corner of the property. This wetland is part of a larger area extending off the property to the west and north. Vegetation within the wetland includes western red cedar trees around the eastern margin of the area. Black cottonwood and red alder are present around the wetland where it extends off the property to the west. Salmonberry is the predominant shrub species. Grades are somewhat lower within the wetland along the west property line where there is an old road running north to south. Vegetation within this section where seasonal water levels are somewhat deeper,includes water parsley. Using the U.S. fish and Wildlife Service wetland classification system (Cowardin et al, 1979), the wetland includes three wetland habitat classes; Palustrine deciduous forest,palustrine scrub-shrub and palustrine emergent habitat. It is our interpretation that the wetland satisfies the criteria for designation as a City of Renton Category 2 wetland. The standard buffer for a category 2 wetland in the City of Renton is 50ft. WILDLIFE HABITAT We have completed a wildlife and habitat evaluation of the project area, The purpose of our work was to document the existing site conditions to identify habitats and potential wildlife use of the property. This work was undertaken to determine if there are critical habitats on the property which would be subject to regulation under Renton City Code which identifies critical habitats as: ":those habitat areas which meet any of the following criteria: i. The documented presence of species proposed or listed by the federal government or State of Washington as endangered,threatened, sensitive, monitor,or priority;and/or ii. The presence of heron rookeries or raptor nesting areas; and/or Category 1 wetlands (refer to subsection B7b(i)of this Section for classification criteria); and/or iv. Portions of streams and their shorelines designated in the Renton Shoreline Master Program, RMC 4-3-090, as Conservancy or Natural(refer to the Renton Shoreline Master Program). c. Mapping: 1. Critical habitats are identified by lists, categories and definitions of species promulgated by the Washington State Department of Fish and Wildlife (Non-game Data System Special Animal Species) as identified in WAC 232-12-011; in the Priority Habitat and Species Program of the Washington State Department of Fish and Wildlife; or by rules and regulations adopted currently or hereafter by the U.S. Fish and Wildlife Service. Project No. 61506 Page No. 3 Mr. Steve Beck March 12, 2007 ii. Referenced inventories and maps are to be used as guides to the general location and extent of critical habitat. Critical habitat which is identified in subsection B5b of this Section, but not shown on the referenced inventories and maps, are presumed to exist in the City and are also protected under all the provisions of this section. iii. The actual presence or absence of the criteria listed above as determined by qualified professionals, shall govern the treatment of an individual building site or parcel of land requiring compliance with these regulations." During the course of site visits to complete the wetland site evaluation we also made notes regarding observation of wildlife species observed on the site. The subject property is occupied by two general vegetation cover type. Lowland mixed forest is the predominant vegetation cover type across the west side of the property. The eastern section of the property is generally open grass land around the area which had been occupied by the existing homes. These cover types are based on the habitat categories listed in the King County Wildlife Study Guidelines for SEPA (1993). Similar categories are listed and described in the King County Wildlife Habitat Profile(1987). The lowland mixed forest on the west side of the property is characterized as second or third growth mixed forest with variation in the relative cover by conifers and deciduous trees. Forest cover on the southern portion of the area is generally dominated by deciduous trees primarily black cottonwood and red alder(Alnus rubra). On the northern section of the area western red cedar western hemlock(Tsuga heterophylla)and Douglas fir(Pseudotsuga menziesii) are present. The eastern section of the property is generally occupied by open grass/forb habitat with scattered landscape and orchard trees and shrubs remaining from the landscaping. There is also a line of large black cottonwood trees along the south side of the area adjacent to NE 2id Street. Wildlife We have prepared a listing of wildlife species(Table 1)observed or likely to be present on the property. This listing is based on species occurrences noted in King County Wildlife Habitat Profile(1987)and on personal experience. Amphibians and Reptiles Other than the Pacific chorus frog (Pseudacris regilla), no amphibians were observed during our site visits. These species are generally inactive during fall and winter and are most frequently encountered during spring and summer. The cover types on this property,particularly the forested wetland and adjacent second-growth forest, should provide habitat for several other species of amphibians. The most likely species are the northwestern salamander (Ambystoma gracile) and long-toed salamander (Ambystoma macrodactylum). The presence of amphibians on the site is limited by the absence of areas of standing water which might provide breeding habitat for amphibians. The most likely reptile to be found in the habitats on this property are garter snakes (Thamnophis spp.). Northern alligator lizard (Elgaria coerulea) are also possible residents. Table I lists other amphibians and reptiles that could be expected in the habitats present on this site. The species listed in Table 1 are based on tables provided by King County(1987) for the habitats described above and on our evaluation of the existing site conditions. Project No. 61506 Page No. 4 Mr. Steve Beck March 12, 2007 Birds Because of their high levels of daytime activity and vocalizations, birds are the most commonly encountered group of vertebrates. Some of the commonly observed species on the site were the black-capped chickadee (Parus atricappilus), American robin (Turdus migratorius), winter wren (Troglodytes troglodytes), and song sparrow (Melospiza melodia). A large number of migratory songbirds including flycatchers, warblers, and vireos are expected on this site during the breeding season. The most likely raptors to use this site are the great horned owl (Bubo virginianus), Cooper's hawk (Accipiter cooperi), and red-tailed hawk (Buten jamaicensis). Table 1 lists other bird species expected in the habitats available on this property. Mammals Most mammals tend to be secretive and nocturnal, and our observations reflect a relatively small proportion of species that may actually exist on the subject property. We observed coyote(Canis latrans)scat on trails around the property. A large nest, probably built by an eastern gray squirrel (Sciurus carolinensis), was located in the deciduous forest near the north side of the property. Other common mammals that are likely to be present on the site include opossum (Didelphis virginiana), deer mouse (Peromyscus maniculatus), and raccoon (Procyon lotor). Several species of bats are also likely to be present in these habitats during the summer. Table 1 lists other mammal species expected to occur in the habitats available on this site. Threatened, Endangered,or Sensitive(TES)Species Critical Habit Two wildlife species included on Washington State listings of TES could be found on or in the vicinity of the subject property. These include the Bald eagle (Haliaeetus leucocephalus), and pileated woodpecker(Dryocopus pileatus). Neither of these species is listed as threatened in the state of Washington. The closest aquatic habitat which might support either bull trout or Chinook salmon (Oncorhynchus tshawytscha), is in May Creek approximately 2 miles south of the property. Bald eagles are found throughout the Puget Sound region. They are most commonly observed along lake or river shores although they may be found foraging over a large area and may roost in larger trees away from bodies of water. No bald eagles were observe on or near the project site. The project site is away from any large bodies of water where they would be likely to build nests. Pileated woodpeckers generally inhabit mature and old-growth forests, or second-growth forests with sufficient large snags and fallen trees (Rodrick and Milner 1991). Pileated woodpeckers are also reported to use open woodlands, parks, and wooded suburbs (Ehrlich et al. 1988) and are regularly seen in those habitats in King County. They excavate cavities in snags or large dead branches for nesting and usually make a new nest cavity every year. Nest snags are usually greater than 27 inches in diameter and taller than 87 feet. There are few large snags within the subject property which would be likely to be used by piloted woodpecker. During our site visits we did not note the presence of any individuals nor did we note any trees with characteristic pileated woodpecker foraging cavities. There is not extensive habitat area on the property which is suitable for pileated woodpecker foraging or nesting. Project No. 61506 Page No. 5 Mr. Steve Beck March 12, 2007 Great blue herons are not included on the Washington State TES lists although the presence of heron rookeries is identified as a critical habitat in the City of Renton. No great blue herons were observed on the site during our site visits and there are no heron rookeries in the near vicinity of the project site. Red-tailed hawks are likewise not included on the Washington State TES lists although raptor nests are identified as critical habitat in the City of Renton. No red tail hawks or nests were observed during our site visits. Based on our review of existing site conditions it is our conclusion that there are no critical habitat areas as defined in the City of Renton codes, within or in near proximity to the Beclan Place project boundary. We trust the information presented is sufficient for your current needs. If you have any questions or require additional information,please call. Sincerely yours, Al erNW1� a�.Jl'JJ Garet P. Munger Project Scientist End.: Figure 1 Vicinity Map Figure 2 Site Map Data Forms (6) Project No. 61 506 Page No. 6 TABLE 1 ANIMAL SPECIES OBSERVED OR POSSIBLE ON-SITE Beclan Place Renton, Washington Common Name Scientific Name AMPHIBIANS Northwestern Salamander Ambystoma gracile Long-toed Salamander Ambystoma macrodactylum Rough-skinned Newt Taricha granulosa Ensatina Ensatina eschscholtzii Western Toad Bufo boreas Pacific Chorus Frog Pseudacris regilla X REPTILES Northern Alligator Lizard Elgaria coerulea Common Garter Snake Thamnophis sirtalis X W. Terrestrial Garter Snake Thamnophis elegans Northwestern Garter Snake Thamnophis ordinoides BIRDS Sharp-shinned Hawk Accipiter striatus Cooper's Hawk Accipiter cooperi Red-tailed Hawk Buteo jamaicensis American Kestrel Falco sparverius Rock Dove ** Columba Livia X TABLE 1 (CONTINUED) ANIMAL SPECIES OBSERVED OR EXPECTED ON-SITE Beclan Place Renton,Washington Common Name Scientific Name BIRDS(Continued) Band-tailed Pigeon Columba fasciata Common Barn-owl Tyto alba Western Screech-owl Otus kennicottii Great Horned Owl Bubo virginianus Rufous Hummingbird Selasphorus rufus X Downy Woodpecker Picoides pubescens X Northern Flicker Colaptes auratus X Pileated Woodpecker Dryocopus pileatus Western Wood Pewee Contopus sordidulus Willow Flycatcher Empidonax traillii Hammond's Flycatcher Empidonax hammondii Pacific Slope Flycatcher Empidonax difcilis Tree Swallow Tachycineta bicolor Violet-green Swallow Tachycineta thalassina N. Rough-winged Swallow Stelgidopteryx serripennis Cliff Swallow Hirundo pyrrhonota Barn Swallow Hirundo rustica Steller's Jay Cyanocitta stelleri X American Crow Corvus brachyrhynchos X Black-capped Chickadee Parus atricappilus X Chestnut-backed Chickadee Parus rufescens Bushtit Psaltriparus minimus Red-breasted Nuthatch Sitta canadensis Brown Creeper Certhia americana Bewick's Wren Thryomanes bewickii X Winter Wren Troglodytes troglodytes Golden-crowned Kinglet Regulus satrapa Ruby-crowned Kinglet Regulus calendula Swainson's Thrush Catharus ustulatus Hermit Thrush Catharus guttatus American Robin Turdus migratorius X Varied Thrush Ixoreus naevius Cedar Waxwing Bombycilla cedrorum European Starling Sturnus vulgaris X Solitary Vireo Vireo solitarius Hutton's Vireo Vireo huttoni TABLE 1 (CONTINUED) ANIMAL SPECIES OBSERVED OR EXPECTED ON-SITE Beclan Place Renton,Washington Common Name Scientific Name BIRDS(Continued) Warbling Vireo Vireo gilvus Red-eyed Vireo Vireo olivaceus Orange-crowned Warbler Vermivora celata Yellow Warbler Dendroica petechia Yellow-rumped Warbler Dendroica coronata Black-throated Gray Warbler Dendroica nigrescens McGillivray's Warbler Oporornis tolmiei Common Yellowthroat Geothlypis trichas Wilson's Warbler Wilsonia pusilla Western Tanager Piranga ludoviciana Black-headed Grosbeak Pheucticur melanocephalus Rufous-sided Towhee Pipilo erythrophthalmus X Song Sparrow Melospiza melodia X White-crowned Sparrow Zonotrichia leucophrys Dark-eyed Junco Junco hyemalis Red-winged Blackbird Agelaius phoeniceus Brown-headed Cowbird Molothrus ater Purple Finch Carpodacus purpureus House Finch Carpodacus mexicanus Pine Siskin Carduelis pinus American Goldfinch Carduells tristis Evening Grosbeak Coccothraustes vespertinus House Sparrow ** Passer domesticus X MAMMALS Common Opossum Didelphis virginiana Trowbridge's Shrew Sorex trowbridgei Vagrant Shrew Sorex vagrans Dusky Shrew Sorex obscurus Pacific Water Shrew Sorex bendirei Shrew-mole .Veurotrichus gibbsi Townsend's Mole Scapanus townsendi Pacific Mole Scapanus orarius Little Brown Myotis Alyotis lucifugus Yuma Myotis A votis yumaensis Long-eared Myotis Myotis evotis TABLE 1 (CONTINUED) ANIMAL SPECIES OBSERVED OR EXPECTED ON-SITE Beclan Place Renton,Washington Common Name Scientific Name MAMMALS (Continued) Eastern Cottontail Sylvilagus floridanus Mountain Beaver Aplodontia rufa Townsend's Chipmunk Eutamias townsendi Eastern Gray Squirrel Sciurus carolinensis Douglas'Squirrel Tamiasciurus douglasi Deer Mouse Peromyscus maniculatus Bushy-tailed Woodrat Aeotoma cinerea Oregon Vole Auicrotus oregoni House Mouse ,V/us musculus Raccoon Procyon lotor Short-tailed Weasel Mustela erminea Long-tailed Weasel Mustelafrenata Striped Skunk :Mephitis mephitis Coyote Canis latrans DATA FORM ROUTINE ON-SITE WETLAND DETERMINATION Describe General Site Site is forested in mixed deciduous/conifer Data Point No.: DP-1 Conditions: trees Site Disturbance? East section had been residential with landscaping. Location: See site Map Buildings recently demolished VEGETATION Dominant Plant Species E ° Dominant Plant Species 1 Alnus rubra Fac T 8 , 2 Populus balsamifera Fac T 9 • 3 Rubus spectabilis Fac S 10 4 Rubus discolor Upl S 11 5 Spiraea douglasii FacW S 12 6 13 7 14 Percent of dominant species that are OBL, FACW,and/or FAC: 80 Is the hydrophytic vegetation criterion met? Yes Rationale: More than 50%species hydrophytic SOIL Soil Type: Alderwood Hydric Soils List: No Histic Epipedon? No Mottles? Slight Gleyed? No Matrix Color: 10YR4/3 Mottle Colors: Depth: 13"-16" Other hydric soil indicators: No Is the hydric soil criterion met? No Rationale: Chroma greater than 2 HYDROLOGY Is the ground surface inundated? No Surface water depth: - Is the soil saturated? Not in upper 18" Depth to free-standing water in probe hole: - Other field evidence hydrology: No Is the wetland hydrology criterion met? No Rationale: Nonhydric soil, no evidence of soil saturation. WETLAND DETERMINATION Are wetland criteria met? No Rationale for wetland decision: .Von hydric soil. Project Name: Beclan Place AlderNW Field Investigator(s): G.Munger 518 North 59th Street Project No.: 61506 Date: 6-20-06 Seattle, Washington 98103 • DATA FORM ROUTINE ON-SITE WETLAND DETERMINATION Describe General Site Site is forested in mixed deciduous/conifer Data Point No.: DP-2 Conditions: trees Site Disturbance? East section had been residential with landscaping. Location: See site Map Buildings recently demolished VEGETATION Dominant Plant Species Dominant Plant Species7:3 cn .C1 45 a 1 Alnus rubra Fac T 8 2 Populus balsamifera Fac T 9 3 Rubus spectabilis Fac S 10 4 11 5 12 6 13 7 14 Percent of dominant species that are OBL, FACW,and/or FAC: 100 Is the hydrophytic vegetation criterion met? Yes Rationale: More than 50%species hydrophytic SOIL Soil Type: Alderwood Hydric Soils List: No Histic Epipedon? No Mottles? Slight Gleyed? No Matrix Color: 10YR4/3 Mottle Colors: Depth: 12"-16" Other hydric soil indicators: No Is the hydric soil criterion met? No Rationale: Chroma greater than 2 HYDROLOGY Is the ground surface inundated? No Surface water depth: - Is the soil saturated? Not in upper 18" Depth to free-standing water in probe hole: - Other field evidence hydrology: No Is the wetland hydrology criterion met? No Rationale: Nonhydric soil, no evidence of soil saturation. WETLAND DETERMINATION Are wetland criteria met'? No Rationale for wetland decision: Non hydric soil. Project Name: Beclan Place AlderNW Field Investigator(s): G.Munger 518 North 59th Street Project No.: 61506 Date: 6-20-06 Seattle, Washington 98103 DATA FORM ROUTINE ON-SITE WETLAND DETERMINATION Describe General Site Site is forested in mixed deciduous/conifer Data Point No.: DP-3 Conditions: trees Site Disturbance? East section had been residential with landscaping. Location: See site Map Buildings recently demolished VEGETATION o Dominant Plant Species Dominant Plant Species ,v 1 Alnus rubra Fac T 8 2 Rubus laciniatus Up! S 9 3 Polystichum munitum Upl H 10 4 11 5 12 6 13 7 14 Percent of dominant species that are OBL, FACW,and/or FAC: 0 Is the hydrophytic vegetation criterion met? No Rationale: Vegetation not hydrophytic SOIL Soil Type: Alderwood Hydric Soils List: No Histic Epipedon? No Mottles? Slight Gleyed? No Matrix Color: 10YR4/3 Mottle Colors: Depth: 12"-16" Other hydric soil indicators: No Is the hydric soil criterion met? No Rationale: Chroma greater than 2 HYDROLOGY Is the ground surface inundated? No Surface water depth: - Is the soil saturated? Not in upper 18" Depth to free-standing water in probe hole: - Other field evidence hydrology: No Is the wetland hydrology criterion met? No Rationale: Nonhydric soil, no evidence of soil saturation. WETLAND DETERMINATION Are wetland criteria met? No Rationale for wetland decision: :Von hydric soil. Project Name: Beclan Place AlderNW Field Investigator(s): G. .Eunger 518 North 59th Street Project No.: 61506 Date: 6-20-06 Seattle, Washington 98103 DATA FORM ROUTINE ON-SITE WETLAND DETERMINATION Describe General Site Site is forested in mixed deciduous/conifer Data Point No.: DP-4 Conditions: trees Site Disturbance? East section had been residential with landscaping. Location: See site Map Buildings recently demolished VEGETATION Dominant Plant Species g Dominant Plant Species 1 Rubus discolor Upl S g 2 Ranunculus repens FacW H 9 3 .Anus rubra Fac T 10 4 11 5 12 6 13_ 7 14 Percent of dominant species that are OBL, FACW, and/or FAC: 66 Is the hydrophytic vegetation criterion met? Yes Rationale: More than 50%species hydrophytic SOIL Soil Type: Alderwood Hydric Soils List: No Histic Epipedon? No Mottles? Slight Gleyed? No Matrix Color: 10YR4/3 Mottle Colors: Depth: 12"-15" Other hydric soil indicators: No Is the hydric soil criterion met? No Rationale: Chroma greater than 2 HYDROLOGY Is the ground surface inundated? No Surface water depth: - Is the soil saturated? Not in upper 18" Depth to free-standing water in probe hole: - Other field evidence hydrology: No Is the wetland hydrology criterion met? No Rationale: Nonhydric soil, no evidence of soil saturation. WETLAND DETERMINATION Are wetland criteria met? .Vo Rationale for wetland decision: Non hydric soil. Project Name: Beclan Place AlderNW Field Investigator(s): G. Munger 518 North 59th Street Project No.: 61506 Date: 6-20-06 Seattle,Washington 98103 DATA FORM ROUTINE ON-SITE WETLAND DETERMINATION Describe General Site Site is forested in mixed deciduous/conifer Data Point No.: DP-5 Conditions: trees Site Disturbance? East section had been residential with landscaping. Location: See site Map Buildings recently demolished VEGETATION Dominant Plant Species b Dominant Plant Species 1 Rubus discolor Upl S 8 2 Ranunculus repens FacW H 9 3 A lnus rubra Fac T 10 4 Thuja plicata Fac T 11 5 12 6 13 7 14 Percent of dominant species that are OBL, FACW, and/or FAC: 75 Is the hydrophytic vegetation criterion met? Yes Rationale: More than 50%species hydrophytic SOIL Soil Type: Alderwood Hydric Soils List: No Histic Epipedon? No Mottles? Slight Gleyed? No Matrix Color: 10YR4/3 Mottle Colors: Depth: 10"-15" Other hydric soil indicators: No Is the hydric soil criterion met? No Rationale: Chroma greater than 2 HYDROLOGY Is the ground surface inundated? No Surface water depth: - Is the soil saturated? Not in upper 18" Depth to free-standing water in probe hole: - Other field evidence hydrology: No Is the wetland hydrology criterion met? No Rationale: Nonhvdric soil, no evidence of soil saturation. WETLAND DETERMINATION Are wetland criteria met? No Rationale for wetland decision: Non hydric soil. Project Name: Beclan Place AlderNW Field Investigator(s): G.Munger 518 North 59th Street Project No.: 61506 Date: 6-20-06 Seattle, Washington 98103 DATA FORM ROUTINE ON-SITE WETLAND DETERMINATION Describe General Site Site is forested in mixed deciduous/conifer Data Point No.: DP-6 Conditions: trees Site Disturbance? East section had been residential with landscaping. Location: See site Map Buildings recently demolished VEGETATION Dominant Plant Species j .45 Dominant Plant Species ate' , 4g 1 Rubus spectabilis Fac S 8 2 Rubus discolor Upl S 9 3 10 4 11 5 12 6 13 7 14 Percent of dominant species that are OBL, FACW, and/or FAC: Is the hydrophytic vegetation criterion met? Yes Rationale: 50%species hydrophytic SOIL Soil Type: Alderwood Hydric Soils List: No Histic Epipedon? No Mottles? Slight Gleyed? No Matrix Color: 10YR4/3 Mottle Colors: Depth: 10"-15" Other hydric soil indicators: No Is the hydric soil criterion met? 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