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Home My WebLink AboutMerlino Short Plat - On Hold - Continued Response LetterknMarCo 9125 Tenth Avenue South o Seattle,. Washington 98108 • (206) 762-9125 Office.- (206) 766-9000 Fax 8/20/2014 Mr. Clark Close City of Renton - Current Planning 1055 South Grady Way Renton, WA 98057 Subject: On Hold Notice -Continued; Merlino Short Plat, LUA 14-000568 Mr. Close, I am writing you on behalf of Merlino Land Development Co. in order to respond to your Iuly 11th "On Hold" Notice. Below I have listed responses to each of your comments and requests for additional information. Please feel free to contact me should you have any additional questions. City Comments: 1) A response to the Independent Secondary Review completed by Associated Earth Sciences, Inc. (AESI). Response: Attached (Attachment A), is Icicle Creek Engineers' response to each of the items included in AESPs Independent Secondary Review. 2) Icicle Creek Engineers, Inc. Geotechnical Engineering Services, Critical Areas Report (dated Apxi123, 2014): Please provide 5 copies of the Following attachments identified in the Ioicle Creek report. Response: Attachment B - Exploration Logs: The exploration logs were a part of the Coal Mine Hazard Report. These logs were previously submitted as part of said report and thus have not been included as part of this response. Attachment C - The "Technical Specifications for the Reinforced Soil Slope (RSS)" from the 1-405 Renton Stage 2 Design/Build Project's Technical Memorandum are included on a thumb drive with this response. The requested report is more than 400 pages in length and thus was not printed as part of this resubmittal. Bella Iiottega LaRenze MJS Properties Pier 1 Strada da Vnlle Casetta logo hiberty Ridge M&M Lease Co. Quarry Industrial Park Sumner'Porra Cava Materials Merlino Holdings II Park Drive [ Sea-SaL Partners 2235 Fifth Avenue Cedar Shores Land Merlino Land Development Park Drive 11 SR 900 901 Monster Road 9125 Tenth Avenue South • Seattle, Washington 98108 • (206) 762-9125 Office • (206) 766-9000 Fax 3) Standard Stream Study: Please provide 5 copies of a report identifying the classification of the streams identified on the plan set. This can be from a project in the vicinity, provided the stream study is within five (5) years of the date of complete application. Response: A new stream study was prepared by Raedeke and Associates, Inc. in order to respond to this comment. That report is included as Attachment B. Thankyou, � � i--� ,,,,�Iimmyi3lais Merlino Land Development Co., Inc. 9125 10th Avenue South Seattle, WA 98108 Ofe 206-762-9125/ Fax 206-763-4178/ Celt 206-255-5153 JBIais@gmccinc.co Bella BoEtega LaDenze tv�JB Propertles Pier 1 Shada da Valle CaseEta Lago Lberty Ridge M&M Lease Co. Quarry Industrial Fark Sumner Terra Cava Materials Merlino Holdings II Park Drive I Sea -Sal Partners 2239 Fifth Avenue Cedar Shores Land Merlino Land Development Park Drive 11 SR 900 501 Monster Road Attachment A ICICLE CREEK E N G I N E E R S Geotechnical, Geologic and Environmental Services August 6, 2014 Jimmy Blais Merlino Land Development Co., Inc. 9125 -10th Avenue South Seattle, Washington 98108 Letter Geotechnical Plans Review Preliminary Merlino Short Plat Response to Comments Geotechnical Third Party Review 700-800 Block Cedar Avenue South Renton, Washington ICE File No. 0864-002 INTRODUCTION This letter presents the results of Icicle Creek Engineers(ICE s) response to Geotechnical Third Party Review comments prepared by Associated Earth Sciences, Inc. (AESI, dated June 30, 2014 — Items 1 through 8) for the Preliminary Merlino Short Plat located within the 700 to 800 Block of Cedar Avenue South in Renton, Washington. Our services were requested by Jimmy Blais of Merlino Land Development Co., Inc. (MLDC). BACKGROUND INFORMATION ICE previously completed the following geotechnical reports related. to the Merlino Short Plat: • ICE, April 23, 2014, Report Geotechnical Engineering Services, Critical Areas Report, Merlino Short Plat— Proposed 7 -Lot Residential Development, Renton, Washington, prepared for MLDC. • ICE, April 23, 2014, Report Geotechnical Engineering Services, Coal Mine Hazard Assessment, Merlino Short Plat — Proposed 7 -Lot Residential Development, Renton, Washington, prepared for MLDC. MLDC provided ICE with preliminary design plans for the project referenced as follows: • Core Design, March 2014, Preliminary Short Plat, Merlino Short Plat, sheets POl, P02, P03 and PO4. • Core Design, February 13, 2014, 1-405 LLC Short Plat, Renton, Washington, sheet 1. • Core Design, August 1, 2014, Merlino Short Plat — Response to Item No. 3 of the Geotechnical Third Party Review, 2 pages. ICE RESPONSE TO THIRD PARTY REVIEW COMMENTS For the purpose of this letter, the title line of AESI comments will be restated in bold type, followed by the ICE response. 29335 NE 20th Street •Carnation, Washington 98014 . wvwv. is is lecree ke nginee rs.com • (425) 333-0093 phone • l425) 995-4036 faz Jimmy Blais Merlino Land Development Co., Inc. August 6, 2014 Page 2 AESI Item No. l —Existing slope versus designed slope and their respective factor of safeties ICE Response — As noted by AESI, the Corridor Design Builders (CDB) August 2009 Memorandum (attached to ICE's April 23, 2014 Critical Areas Report), indicated that the Reinforced Soil Slope (RSS) was evaluated for slope stability with the assumption that residence would be constructed in the level area created at the top of the RSS where it borders Cedar Avenue South, In ICE's April 23, 2014 Critical Areas Report (page 7, Section 8.2.1.1) we recommended (b) a building setback of 10 feet from the portion of the Engineered Fill slope area to the north of Lot 1, and (c) a building setback of 10 feet from the portion of the Engineered Fill slope area to the south of Lot 7. In addition, for the analysis of slope stability for the RSS the August 2009 CDB Memorandum included a "traffic surcharge' of 250 pounds per square foot (psf) across the entire level area at the top of the RSS. The 250 psf traffic surcharge is the same as for modeling a typical residential structure, though typically the surcharge would not be carried across the entire level area (the surcharge would begin 25 feet back from the top of RSS in this case to satisfy the building setback). For this reason, in our opinion the proposed siting of homes with a 25 -foot setback from the top of RSS is a conservative plan and is within the base assumptions for evaluating the adequate slope stability factor of safety by the CDB August 2009 Memorandum. ICE does not need to review the final design plans provided that the structures are of typical two-story, wood -frame construction and are situated within the building envelope for each lot as shown on sheets 1, P01 and P03, AESI Item No. 2 —Wall design over proposed fill on recently construeted steep slopes ICE Response — We understand that the wall design has not been finalized for the Preliminary Plat phase. ICE's response to this comment is deferred until a later phase in the plat process. AE51 Item No. 3 —Increased drainage discharge onto WSDOT downstream steep slopes and drainage ditch and how it would affect toe issues for that existing slope ICE Response — ICE reviewed the above -referenced design plan by Core Design (sheet P03) and Core Design's August 1, 2014 Technical Memorandum. Based on our review of this memorandum, Core Design has concluded that the increased stormwater discharge to the current rock -lined ditch has more capacity to convey the 100 -year undetained peak flow. Based on this statement, the stormwater discharge has been evaluated and designed by Core Design to provide for safe stormwater discharge onto the slope area (within the existing rock -lined ditch), consistent with ICE's recommendation in our April 23, 2014 Critical Areas Report. AESI Item No. 4—Soil liquefaction ICE Response —This AESI comment did not require an ICE response. AESI Item No. 5 —Slope Stability Analysis ICE Response —Same response as for AESI Item No. 1. A conservative assumption using a traffic surcharge of 250 psf extending across the entire level area bordering Cedar Avenue South was used in the CDB slope stability analysis. The surcharge of 250 psf is also commonly used to model residential structures in slope stability analysis. For the current project plans, the residential structures will be setback at least 25 feet from the top of the RSS. For this reason, the slope stability analysis completed Icicle Creek Engineers 0864002/080614 Jimmy Blais Merlino Land Development Co., Inc. August 6, 2014 Page 3 by CBD is a conservative approach and provides for adequate factor of safety (factor of safety greater than 1.5). ICE does not need to review the final design plans provided that the structures are of typical two-story, wood -frame construction and are situated within the building envelope for each lot as shown on sheets 1, POS and P03. AE51 Item No. 6 —Anticipate weights before and after constructed plat (weight analysis would assume full water weight of soils per cubic feet due to required flow control BMPs for each home) ICE Response — In our opinion, the moist unit weight of 130 pounds per cubic foot (pcf) is a relatively high weight for compacted soil, and certainly reasonable. We do not expect that soil moisture will increase (thereby increasing soil moist unit weight) because roof downspouts, yard drains and driveway/yard drains will be connected to the stormwater collection system. More impervious surface will result post -construction that would have an effect of actually decreasing soil moisture content. However, this effect is probably not measureable or even important for considering slope stability. The important factor is that soil moisture should not increase as a result of site development and the 130 pcf is a reasonable value to have been used in the CDB slope stability analysis. ICE does not need to review the final design plans provided that the stormwater disposal from these houses and other impervious surfaces is conveyed (rather than dispersed or infiltrated) to a closed collection system that disposes of the water at an approved location. AE51 Item No. 7 —Coal seam impacts from past boring records CE Response — ICE has reviewed Core Design sheet P02 that shows the location of the High Coal Mine Hazard Areas (the hazard location is from ICE's May 2009 DRAFT report that was prepared for MLDC) and the locations for structures (retaining wall, vault, water line) shown on sheet P03. It appears that the stormwater vault is located outside of the High Coal Mine Hazard area so no mitigation is required for the vault associated with coal mine hazards. However, the east end of the retaining wall extends about 10 feet into the High Coal Mine Hazard area. At this time, the specific retaining wall design has not been determined. We strongly suggest using a gravity block wall for this purpose if the wall needs to extend into the High Coal Mine Hazard area. It also appears that a 6 -inch diameter water main is proposed to extend about 25 feet into the High Coal Mine Hazard area. The water main should be sleeved with a structural pipe capable of full support should the loss of up to 10 feet of soil under the pipe occur. AESI Item No. 8 —Effectiveness of proposed mitigating measures for impacts ICE Response — We recommend that ICE review the final design plans associated with mitigating the east end of the retaining wall and the water line that extend into the High Coal Mine Hazard area. The stormwater detention vault appears to be sited outside of the High Coal Mine Hazard area and does not require further review by ICE related to Coal Mine Hazards, Icicle Creek Engineers 0864002/080614 Jimmy Blais Merlino Land Development Co., Inc. August 6, 2014 Page 4 We trust this information meets your present needs. If you have any questions or if we can be of further assistance, please call. 871 BRIAN R. DEAMAN Document lD: 0864002.response Submitted via email (PDF) and surface mail (two original copies) Yours very truly, Icicle Creek Engineers, Inc, A Brian R. Beaman, PE, LEG, LHG Principal Engineer/Geologist/ Hydrogeologist Icicle Creek Engineers 0864002/080614 14711 Nc 29Th Place, So le 161 . 13e levue,,'Washingtnn 98r",07 144 Ph 425.888.7877 tidevw.rnrPrl�sinnin� grim To: Jimmy Blois From: Sheri Murata, PE Date: August 1, 2014 Re: Merlin Short Plat — Response to Item No. 3 of the Geotechnical Third Party Review The following memorandum is in response to the following excerpt is taken from Geotechnical Third Party Review dated June 30, 2014 by Associated Earth Sciences. Increased dr•aiva_e discharge onto SS'SDT)`F dr�s+•nstreatn steep slopes and drainase stitch and horn it would affect Toe issues for Tlt<ar emsting slope P}aft "iSaecr P(93 .shows a prottrr•.�5 12-isarlt-alste: ouzleT pipe e�tettdisr� soncb�r*,eurerlr- from the proposed defentcnrt Welt and disc3asrgvta ar rhe upper parrism Of the existing, draar,ze dtrch. The April 232 21314 Icicle Green Critical Areas Report psalsides the teconxntendati ai that ^7110 samnsw e rantirjj ar u,is,i ed to lea , ro like slope tar ci,"tcr 171an OW, Planned di7chagf »rr, the pmpascd srom?wru tic delern*on vault into alae ctza riyig 1't. )1. Iinc=d chills that tunis Parallel rc and citing rhe rorzir cage t�fihe rusrzatg gravel access roigd}. We rrconurend tikes Lore Design c .aiurfe pianned J4719V fro?v t7ac 3Zk7P77nivic? vx nlr rand rhe jai an Of r ^ac cxisrin� rortiined ditch r0 aefOwynodare 1111 ficx•. " TXe concur with ilte. Icicle Creekreport, and rex-xmtattend that this. evaluation be. completed bis tlie project civil eigineer and rv,.dev.ed bT the project peon a cat mgtaeer. The flow to the existing ditch north Existint; Conditions 1.38 ac Till Grass Develooed Conditions 0.95 ac hnpervious 0.65 ac Till -Grass It was determined that the exis{ing 2 -year peak flow is 0.068 cfs and the 10 -year peak flow is 0.13 cfs. The developed (detained) peaks are 0.037 cfs and OA87 respectively so less runoff will be discharged to the ditch in the developed condition up to the 10 -year event. The City's detention requirements only require sites to match the pre -developed 2 -year and 10 -year peaks (in addition to matching 50% of the 2 -year to the full 50 -year durations), the vault will discharge more storm water to the ditch in the developed condition beyond the 10 -year event. However, based on Mannings Equation below, the existing ditch has more than enough capacity to convey the 100 -year undetained peak flow. J:\2004\04139M\Documents\Engineering\Tech Memo\2014_08_01 Ex Ditch Tech Memo.dacx of the WSDOT access road in the existing and developed conditions were computed based on the following areas: (See Figure 1 attached) Existint; Conditions 1.38 ac Till Grass Develooed Conditions 0.95 ac hnpervious 0.65 ac Till -Grass It was determined that the exis{ing 2 -year peak flow is 0.068 cfs and the 10 -year peak flow is 0.13 cfs. The developed (detained) peaks are 0.037 cfs and OA87 respectively so less runoff will be discharged to the ditch in the developed condition up to the 10 -year event. The City's detention requirements only require sites to match the pre -developed 2 -year and 10 -year peaks (in addition to matching 50% of the 2 -year to the full 50 -year durations), the vault will discharge more storm water to the ditch in the developed condition beyond the 10 -year event. However, based on Mannings Equation below, the existing ditch has more than enough capacity to convey the 100 -year undetained peak flow. J:\2004\04139M\Documents\Engineering\Tech Memo\2014_08_01 Ex Ditch Tech Memo.dacx Blaise, Jimmy Response to Item No. 3 of the Geotechnical Third Party Review = L A R'.�.yrc 71 where t7 = discharge (cis) a = velocity (fps) i = area (sf) n = Mann ng's roughness coefficient: see Tablc+2.1.1) below R = hydraulic radius = area: ;netted perimeter (ft) S = slope afthe energy grade line (it.,ft) Aub ist 1, 2014 Page 2 The existing "V" ditch has a top width of approximately 7 feet, a depth of 1 foot, a slope of 27% and a n value of 0.040 which results in a capacity of 40.8 cfs. The 100 -year undetained peak flow is 0.59 cfs, so the existing ditch has more than enough capacity to convey the developed flows. J:\2004\a4139M\Documents\Engineering\Tech Memo\2014_OS_01 Ex Ditch Tech Memo.docx SGJTH "ITN 5TREET R2013a N, u 27 31 1 F \AND 20 ED Ni t,Q2 ... II OG T3 III I 000 I O. E na SEWN ?Dy i jJ DDDm m O O E. o ED m 0 Ir 6AA ODOR )Nm �I O m p i i 12 OEEA) ,a 11 —m ora X D P A O m p A mF Ip Z T ~O T m If p CIA n � 31 I / j i E) / O p y ` O cl O � MERLINOSHORTPLAT EXISTINGVSDEVELOPED oa�� Renton, w n;ngtnn FLOWS TO EXISTING E FNG MEER IN G PLA"HJJYM 5 UR V6 7YJ N G Eden DITCH YYSCN:1►1[N\Ipil�iu IT;7: ►1\TIiiL� August 8, 2014 Wetland & Wildlife Sciences Wildlife Ecology Landscape Architecture Ta Mr. Jimmy Blais, Merlino Land Development Co., Inc. From William J. Taylor, M.S. Aquatic Scientist Raedeke Associates, Inc. RE: Merlino Short Plat Renton —Standard Stream Study (RAI Project No. 2014-049-001) At your request, this technical memorandum is intended to provide a Standard Stream Study following the Renton Municipal Code (City of Renton 2014a) for two stream channels adjacent to the Merlino Renton Short Plat project in Renton Washington. This assessment is intended to provide a narrative of the stream and surrounding vegetated conditions, and proposed classification of the stream channels adjacent to the site. We visited the project site on August 4, 2014 to review the existing stream channel and vegetation conditions - 0. s onditions. o.'s 2023059085 and 0007200 194) located in the 800 block of Cedar Avenue S., in the City of Renton, King County, Washington. Specifically, the property is located in the northwest quarter of the northwest quarter of Section 20, Township 23 North, Range 5 East, W.M., as depicted on the Site Map and Preliminary Grading and Utility Plan for the project by Core Design, Inc. (2014; attached). SITE DESCRIPTION The project site currently consists of a level graded terrace (Photo 1), with adjacent fill slopes graded at 1.75:1 that extend down to the Interstate 404 right-of-way to the west (see attached Site Map, Core Design, Inc. 2014). The graded terrace is dominated by grasses and various weedy herbs. The graded slopes are vegetated with sapling Douglas - fir (Pseudotsuga melt=iesii) and red alder (Alnus rubra), with patches of Himalayan blackberry (Rubus armeniacus), snowberry (Symphoricarpos albus), giant horsetail (Equisetum telmateia), and a variety of grasses. 9510 Stone Avenue N. Seattle, WA 98103 206-525-8122 www.raedeke.com Mr. Jimmy Bhns August 4, 2014 Page 2 The two stream channels of interest occur on the parcel directly adjacent and south of the project site, in parcel -9163, owned as public right of way by the Washington State Department of Transportation (WSDOT; see attached Site Map, Core Design, Inc. 2014). The stream channels lie within the north margin of the wooded portion of the WSDOT site and flow east to west parallel to each other. They are tributary to Thunder Hill Creek and confluence with the creek shortly prior to Thunder Hill Creek passing beneath Interstate 405. Thunder Hill Creek then becomes Rolling Hills Creek, which is tributary to Springbrook Creek. No salmonids are expected to occur in Thunder Hill Creek, and likely do not exist in the downstream reaches until much lower in the system, closer to where Rolling Hills Creek joins Springbrook Creek. STREAM NARRATIVE AND CLASSIFICATION The stream channels were previously surveyed and located on the short plat plan layout provided by Core Design, Inc. (Attachment 1). A visual assessment of the site in the vicinity of the stream channels was conducted to: 1. confirm the channel alignments' relative acctuacy of location on the site plan, 2. characterize the channel conditions and riparian vegetation, and 3. provide recommended stream classifications for each stream. The two streams are identified as streams B and C, with stream B occumng farther south than stream C. IN stream channel occurs on the map of Renton Water Classes (Renton 2014b). One site specific past report is that provided by Talasaea Consultants (2005). The Washington Department of Transportation has conducted a stream mitigation planting project in the vicinity of the lower portions of streams B and C (Ross Fenton, WSDOT, pers. comm. August 6, 2014). Both stream B and stream C are very similar in characteristics. The two streams are only approximately 40 to 60 feet apart from each other, share a common riparian corridor of similar composition (Photo 2), are approximately four to five feet in bank full width, and both are incising heavily in the native soils (Photos 3 and 4). The Web Soil Survey (USDA NRCS 2014) indicates the site comprises soils of Alderwood and Kitsap soils, and Beausite gravelly sandy loam. Streams B and C merge prior to joining Thunder Hills Creek (Talasaea 2005). Stream B flows through a previously identified Class 3 wetland (Talasaea 2005) near the terminus of Stream B before joining with Stream C. This wetland was described as palustrine emergent wetland dominated by reed canarygrass (Phalaris arundinacca) with salmonberry (Rubies spectabilis) and Himalayan blackberry (Rubus discolor) along its Mr. Jimmy Blais August 4, 2014 Page 3 perimeter (Talasaea 2005). Soils appeared to contain a layer of sand, apparently eroded mtwash from Stream B. Stream B had a very small degree of flow in the channel (approximately 0.25 gallons per minute) during our August 4, 2014 site visit, and appears it may remain marginally perennial under normal rainfall years. Because Stream B appears to be a naturally occurring, perennial, non -salmonid bearing feature, it appears to meet the criteria for a CIass 3 stream per the City of Renton (2014) code, which requires a 75 -foot standard buffer. Stream C originates from a stormwater outfall located at the south end of Cedar Avenue S. (Photo 2). Similarly, an apparent accumulation of material eroded from the incising of the stream channel occurs at the base of the slope where the gradient flattens. This area has been revegetated (Photo 5) as part of a W SDOT mitigation for replacement of the Thunder Hills Creek culvert I405 underpass (Ross Fenton, WSDOT, pens. comm. August 6, 2014). Occassional high flows may continue to overflow the channel and flow into this planting area, but incision of the channel as it circumvents this mitigation area suggests flows stay largely confined now to the channel. Because Stream C does not appear to exist in historical photographs (Talasaea 2005), and flows directly from discharge from a roadway stormdrain system, is intermittent and non - salmonid -bearing, meets the criteria to be classified as a Class 5 stream under the City of Renton (2014a) code. As such the City of Renton (2014a) has no standard buffer requirements for Stream C.. VEGETATION COVER OF THE STREAM CORRIDORS As part of our site visit on August 4, 2014 we characterized the vegetation of the riparian communities of two streams (Stream B and Stream C) located adjacent to the Merlino property to the south. The drainages are located in proximity to one another, and in general share a riparian corridor. Vegetation in the ri parian corridor in the upstream reach is characterized by a deciduous forest canopy dominated by a mixed community of big -leaf maple (Acer macrophyllum, FACU) and balsam poplar (Populus balsamifera, FAC) extending from Cedar Avenue south approximately 200 feet. These trees are approximately 30 to 40 years in age and provide significant shading and temperature moderation (50 to 60 percent canopy coverage) for the streams. Very few juvenile cottonwood and big -leaf maples were observed in the upper reach, suggesting a low level of recruitment. The understory is dominated by dense stand of both native and invasive species including common snowberry (Symphoricarpos albus, FACU), Himalayan blackberry (Rebus ameniacus, FACU), trailing blackberry (Rubus ursinus, FACU), sword fern (Polystichum munitum, FACU) and lady fern (Athyrium filix femina, FAC). Mr. Jimmy Blais August 4, 2014 Page 4 The composition of the riparian corridor remains consistent in the lower reach, with big - leaf maple and balsam poplar providing significant canopy cover (40 to 50 percent shading) over the two drainages. Trees in the lower reach are approximately 30 to 40 years in age and extend from the property boundary south through the riparian corridor. Snowberry, Himalayan blackberry, and trailing blackberry are the dominate understory vegetation. Reedcanary grass (Phalaris anzndecea, FACW), herb Robert (Geranium robertianum, FACll), sword fern, and common velvet grass (Holcus lanatus, FAC) were also observed scattered throughout the lower reach. The forests cover transition to a mixture of deciduous and coniferous trees south of the drainages. A downed balsam poplar of significant size (approximately 4 feet in diameter) was observed across the lower channel of Stream C. Other woody debris is scattered throughout the drainages and riparian corridor, providing abundant habitat opportunities. The lower portion of Stream B flows through a small emergent wetland. The wetland receives hydrology primarily from surface flow and hydrologic connectivity between Streams B and C. At the time of our investigation, the wetland vegetation was primarily reedcanary grass, although some Himalayan blackberry and snowberry were observed along the wetland boundaries. A series of juvenile western arborvitae (Thzya plicata, FAC) and Oregon grape (Mahonia aquafolium, FACED were observed planted at the base of the hill at the southern boundary of the Merlino property, likely as part of the WSDOT stream mitigation planting area (Photo 5). The hillside and most of the parcel have been seeded with a grass mixture for erosion control. ECOLOGICAL FUNCTIONS PROVIDED BY THE STREAM AND RIPARIAN AREA AND POTENTIAL IMPACTS Because the stream channels provide primarily storm event flows or very low base flows to Thunder Hill Creek, very little transport of organic matter or insect prey likely occurs. Existing impacts of sediment transport from continued incision of the channel likely transport sediment to Thunder Hill Creek. The riparian canopy does provide southern exposure shading of the channels adjacent to the creek. This shading will contribute some temperature control during summer storm events; however, flow to Stream C originates from roadway runoff from Cedar Avenue S. and so will be originally warm runoff from the street surface. Very few birds were detected during our field visit, but numerous scat from omnivorous mammals was observed, and the forested area encompassing the streams likely provides habitat for a variety of wildlife. The project site is currently level -graded in preparation for building construction, an d so no additional grading is planned except for excavation of building sites, construction of the stormdrain system within the western half of Cedar Avenue S., and relocation of part of the existing WSDOT access road (see attached grading plan). Mitigation for these Mr. Jimmy Blais August 4, 2014 Page 5 impacts include erosion control and replanting after site construction and relocations of the road. Because the streams and riparian corridor occur on the adjacent property, no direct impacts to vegetation or trees will occur. Itis expected that there will be less stormwater runoff from Cedar Avenue S. to the discharge point at the head of Stream C. In the developed conditions, storm water from the short plat and the west half of Cedar Avenue S will be collected by a proposed storm drain system in the street and drain to a combination detention and water quality vault located in the cul-de-sac on the south end of the project. The vault will discharge to an existing rock lined ditch on the north side of the existing WSDOT access road which heads southwest and until the bottom of the 2:1 slope (constructed as part of the I405 widening) where it drains north to a Type 2 Catch basin with a bird cage structure. From this point the stormwater drains west into the conveyance system in I-405 and finally discharges to a W SDOT pond west of I-405 and east of S 3rd Street. LnnTATIONS We have prepared this report for the exclusive use of Merlino Land Development Co., Inc. and their consultants. No other person or agency may rely upon the information, analysis, or conclusions contained herein without permission from Merlino Land Development Co., Inc. The determination of ecological system classifications, functions, values, and boundaries is an inexact science, and different individuals and agencies may reach different conclusions. With regard to streams and wetlands, the final determination of their classification or boundaries for regulatory purposes is the responsibility of the various agencies that regulate development activities in streams and wetlands_ We cannot guarantee the outcome of such determinations. Therefore, the conclusions of this report should be reviewed by the appropriate regulatory agencies. We warrant that the work performed conforms to standards generally accepted in our field, and prepared substantially in accordance with then -current technical guidelines and criteria. The conclusions of this report represent the results of our analysis of the information provided by the project proponent and their consultants, together with information gathered in the course of the study. No other warranty, expressed or implied, is made. Mr. Jimmy Blais August 4, 2014 Page 6 LITERATURE CITED Core Design. 2014. Site Map and Preliminary Grading and Utilities Plan, Merlin Short Plat. March 2014. Fenton, Ross. 2014. Personal telephone communication requesting information about the vegetation planting mitigation site adjacent to Merlino Renton Short Plat. WSDOT, Bellevue, WA. August 6, 2014. Renton, City of 2014a. Renton Municipal Code. Title IV, Chapter 8-120 — Submittal Requirements, and Chapter 3-050 — Critical Areas Regulation. Current through Ordinance No. 5719, passed July 14, 2014. Renton, City of. 2014b. Renton Water Classes Map. City of Renton Municipal Code 4- 3-050 (Q) Maps. Talasaea Consultants. 2005. Wetland study, stream assessment, habitat study, watershed restoration and mitigation plan. Revised 3 October, 2005. U.S.D.A. Natural Resources Conservation Service. 2014. On-line Web Soil Survey. http://websoilsurvey.nres,usda.gov. Accessed August 6, 2014. PHOTOS Photo 1. View of Merlino Renton Short Plat project site existing conditions. The vegetated corridor of Streams B and C is seen at the south end of the site. August 4, 2014. Photo 2. Edge of shared canopy covering both Streams B and C through the site, and location of stormdrain outfall origin of Stream C. August 4, 2014. Photo Plate 1 Raedeke Associates, Inc. 2014-049-001 Merlino -Renton August 8. 2014 Photo 3. Typical stream bed substrate and incised channel observed in Stream B, with slight flow in channel. August 4, 2014. Photo 4. Typical stream bed and incised channel observed in August 4, 2014. Stream C. 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