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HomeMy WebLinkAboutSR_ERC_Report_VEK_on_Aberdeen_Townhomes_210405DEPARTMENT OF COMMUNITY AND ECONOMIC DEVELOPMENT Project Location Map SR_ERC_Report_VEK on Aberdeen Townhomes (002) ENVIRONMENTAL REVIEW COMMITTEE REPORT ERC Meeting Date: April 5, 2021 Project File Number: PR19-000448 Project Name: VEK on Aberdeen Townhomes Plat Land Use File Number: LUA19-000280, PP, SA-A, ECF, MOD, MOD, MOD Project Manager: Angelea Weihs, Associate Planner Owner/Applicant: Nord West Properties, LLC, 14435 NE 40th ST, Apt. B101, Bellevue, WA 98007 Contact: Nicole Mecum, PE, Encompass Engineering and Surveying, 165 NE Juniper St., Suite 201, Issaquah, WA 98027 Project Location: 957 Aberdeen Ave NE Project Summary: The applicant is requesting Preliminary Plat, Unit Lot Subdivision, Hearing Examiner Site Plan Review, Environmental (SEPA) Review, a Street Modification, an Open Space Modification, and a Unit Lot Drive Modification for 12 townhomes. The subject site consists of one parcel (Parcel number 3119900066) located at 957 Aberdeen Ave NE. The subject site is 54,057 square feet (1.24 acres) and is located in the Residential Multi-Family (RMF) zoning district and the Residential High Density (HD) land use designation. The site currently contains one single family residence and several accessory structures, all of which are proposed for removal in order to construct two new townhome buildings, both with six units each. The applicant proposes to increase the maximum wall plate height up to 42 feet and increase the number of stories to four stories for both townhome structures though the Site Plan Review process. The proposed project would result in a net density of 15.13 du/ac. The Unit Lot Subdivision is proposed to be subdivided into 12 lots, three landscape tracts, two common open space tracts, one unit lot drive tract, and one critical area tract. The proposed unit lots would range in size from 864 sf to 1,106 sf. Access to all 12 units is proposed via a new unit lot drive extending from Aberdeen Ave NE. High landslide hazards, high erosion hazards, protected and sensitive slopes, a category III wetland, and a type Ns stream (John's Creek) are mapped on the project site. Of the 90 significant trees located on the project site, 29 significant trees are proposed for removal. Exist. Bldg. Area SF: 1,390 SF Proposed New Bldg. Area (footprint): Proposed New Bldg. Area (gross): 9,206 SF 25,156 GSF Site Area: 54,057 SF Total Building Area GSF: 25,156 GSF STAFF RECOMMENDATION: Staff Recommends that the Environmental Review Committee issue a Determination of Non-Significance - Mitigated (DNS-M). DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2 City of Renton Department of Community & Economic Development VEK on Aberdeen Townhomes Plat Staff Report to the Environmental Review Committee LUA19-000280, PP, SA-A, ECF, MOD, MOD, MOD, Report of April 5, 2021 Page 2 of 11 SR_ERC_Report_VEK on Aberdeen Townhomes (002) PART ONE: PROJECT DESCRIPTION / BACKGROUND The applicant is requesting Preliminary Plat, Unit Lot Subdivision, Hearing Examiner Site Plan Review, Environmental (SEPA) Review, a Street Modification, an Open Space Modification, and a Unit Lot Drive Modification for 12 townhomes. The subject site consists of one parcel (Parcel number 3119900066) located at 957 Aberdeen Ave NE. The site currently contains one single family residence and several accessory structures, all of which are proposed for removal in order to construct two new townhome buildings, both with six units each. The applicant proposes to increase the maximum wall plate height up to 42 feet and increase the number of stories to four stories for both townhome structures though the Site Plan Review process. The proposed project would result in a net density of 15.13 du/ac. A Unit Lot Subdivision is proposed that would subdivide the subject site into 12 lots, three landscape tracts, two common open space tracts, one unit lot drive tract, and one critical area tract. One of the 12 Unit Lot Subdivision lots would front on and face Aberdeen Ave NE and 11 units would face common open space. There are a total of ninety (90) on-site significant trees on the subject property. The applicant proposes to remove 29 of the existing 90 significant trees located on site. The subject site is bordered by similar Residential Multi-Family (RMF) zoning to the north and south and across Aberdeen Ave NE to the east. The surrounding units to the north and south are multi-family apartment housing. Existing uses to the east across Aberdeen Ave NE include single-family. The project site is located in the Highlands Community Planning Area. The subject site is 54,057 square feet (1.24 acres) and is located in the Residential Multi-Family (RMF) zoning district and the Residential High Density (HD) land use designation. The overall net density of the project is 15.13 dwelling units per net acre and the 12 lots would range in size from 864 square feet to 1,106 square feet (Exhibit 2). The project site fronts Aberdeen Ave NE along the east property line (Exhibit 2). All vehicular access to the project would be from Aberdeen Ave NE via a 21-foot wide unit lot drive that runs along the north side of the development (Tract B). The applicant is requesting a Unit Lot Drive Modification in order to increase the number of units that access from the proposed unit lot drive to 12 units, rather than the maximum of 9 units permitted by code. The applicant is requesting a street modification (Exhibit 17) for cross section changes to the Aberdeen Ave NE frontage improvements, to allow for a 6-foot wide planter strip and 5-foot wide sidewalk, resulting in a 4.5-foot right-of-way (ROW) Dedication (pending final survey) in lieu of the full half street standards. The applicant is proposing a stormwater detention tank, designed per Section 5.1.2 of the 2017 City of Renton Surface Water Design Manual (RSWDM), that would be utilized to mitigate all developed onsite and offsite stormwater flows for the project. An Oldcastle Biopod filtration device is proposed to provide for enhanced water quality treatment. The existing site drains to a low point in the form of a vegetated drainage channel, which discharges to the western edge of the property and it is conveyed off-site under Interstate 405 (I-405). The project proposes to emulate the existing site drainage patterns for the developed stormwater runoff. High landslide hazards, high erosion hazards, protected and sensitive slopes, a Category III wetland, and Type Ns streams are mapped on the project site. The applicant has submitted a Geotechnical Engineering Report, Preliminary Technical Information Report, Arborist Report, and Critical Areas Report with the project application. PART TWO: ENVIRONMENTAL REVIEW In compliance with RCW 43.21C.240, the following environmental (SEPA) review addresses only those project impacts that are not adequately addressed under existing development standards and environmental regulations. A. Environmental Threshold Recommendation Based on analysis of probable impacts from the proposal, staff recommends that the Responsible Officials: Issue a DNS-M with a 14-day appeal period DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2 City of Renton Department of Community & Economic Development VEK on Aberdeen Townhomes Plat Staff Report to the Environmental Review Committee LUA19-000280, PP, SA-A, ECF, MOD, MOD, MOD, Report of April 5, 2021 Page 3 of 11 SR_ERC_Report_VEK on Aberdeen Townhomes (002) B. Mitigation Measures 1. Project construction shall comply with the recommendations found in the Geotechnical Report prepared by The Riley Group, Inc. (dated November 27, 2018) for the proposed Unit Lot Subdivision, and any updated report(s) associated with the building and construction permits to ensure compliance with the intent of the initial report. 2. The applicant’s geotechnical engineer shall review the project’s construction and building permit plans to verify compliance with the geotechnical report(s). The geotechnical engineer shall submit a sealed letter stating that he/she has reviewed the construction and building permit plans and in their opinion the plans and specifications meet the intent of the report(s). C. Exhibits Exhibit 1: Environmental Review Committee (ERC) Report Exhibit 2: Site Plan Exhibit 3: Neighborhood Detail Map Exhibit 4: Unit Lot Subdivision Plat Map Exhibit 5: Landscape Plan and Tree Retention Worksheet, prepared by Cramer Design Consultants, Inc., dated June, 13, 2019 Exhibit 6: Tree Retention Plan, prepared by Cramer Design Consultants, Inc., dated December 11, 2020 Exhibit 7: Arborist Report, prepared by Shoffner Consulting, dated January 11, 2021 Exhibit 8: Design Review Package with Floor Plans and Building Elevations, prepared by Monsef Design Studio, dated December 11, 2020 Exhibit 9: Preliminary Technical Information Report, prepared by Encompass Engineering & Surveying, dated December 11, 2020 Exhibit 10: Civil Plan Set (Cover Sheet, Preliminary Grading & Drainage, Preliminary Sewer & Water Plan, Street Profile and Cross Sections), prepared by Encompass Engineering & Surveying, dated December 11, 2020 Exhibit 11: Geotechnical Engineering Report, prepared by The Riley Group, Inc., dated September 2, 2020 Exhibit 12: Environmental Checklist Exhibit 13: Construction Mitigation Description Exhibit 14: Supplemental letter from The Riley Group, Inc., dated April 23, 2020 Exhibit 15: Secondary Geotechnical Engineering Review letters, prepared by GeoEngineers, dated October 15, 2020 and October 30, 2020 Exhibit 16: Critical Area Designation, prepared by Beaver Creek Environmental Services, Inc., dated October 16, 2020, and Wetland Buffer Mitigation Plan prepared by Beaver Creek Environmental Services, Inc., dated February 22, 2021 Exhibit 17: Street Modification Request Exhibit 18: Traffic Technical Memo Exhibit 19: Advisory Notes DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2 City of Renton Department of Community & Economic Development VEK on Aberdeen Townhomes Plat Staff Report to the Environmental Review Committee LUA19-000280, PP, SA-A, ECF, MOD, MOD, MOD, Report of April 5, 2021 Page 4 of 11 SR_ERC_Report_VEK on Aberdeen Townhomes (002) D. Environmental Impacts The Proposal was circulated and reviewed by various City Departments and Divisions to determine whether the applicant has adequately identified and addressed environmental impacts anticipated to occur in conjunction with the proposed development. Staff reviewers have identified that the proposal is likely to have the following probable impacts: 1. Earth Impacts: The applicant submitted a Geotechnical Engineering Report, prepared by The Riley Group, Inc. (RGI), dated November 27, 2018, and subsequently revised on September 2, 2020 (Exhibit 11), with the project application. The subject site is a rectangular-shaped parcel of land, approximately 1.24 acres in size. The eastern portion of the property descends generally west with an elevation change of approximately 28 feet over a horizontal distance of 290 feet. The area is vegetated with grass, decorative plants and shrubs, a garden, fruit trees, and scattered medium to large trees. The western portion of the property descends generally west with an elevation change of approximately 84 feet over a horizontal distance of 300 feet. Slope gradients range from about 40 percent to over 120 percent. The area is vegetated with medium to large trees, with an undergrowth of ferns, mixed brush, and blackberry brambles. RGI observed the excavation of three (3) test pits at the project site, to a depth of approximately 9 feet below existing site grades. The soils encountered during field exploration included loose to medium dense silty sand with varying amounts of gravel, becoming dense at depths of three to six feet, over very stiff silt. The report states that the site soils are not conducive to infiltration and infiltration is not recommended on the site due to the relatively impermeable soils and the slopes on the west side of the site. Groundwater seepage was encountered at 5.5 to 6.5 feet at one test pit location during the subsurface exploration. Surface seepage was observed near the test pit location and adjacent to and within the small drainage channel extending east through the western portion of the site, and in John Creek extending south through the site near the western property line. Groundwater levels during construction or at other times may be higher or lower than measured levels and groundwater level fluctuations should be considered when developing the site. RGI reviewed the results of the field and laboratory testing and assessed the potential for liquefaction of the site’s soil during an earthquake. Since the site is underlain by glacially consolidated deposits, RGI considers that the possibility of liquefaction during an earthquake is minimal. RGI noted the presence of geologic hazards on the project site, including sensitive and protected slopes, and landslide hazards. The report states that the site slopes have gradients in the range of about 40 percent to over 120 percent, and meet the criteria of Protected Slopes per City code. The site is mapped as a high landslide hazard area with slopes greater than 40 percent in the western portion of the site. The area also appears to be underlain by silt deposits. The report states that the slopes in the western portion of the site meet the criteria of High Landslide Hazards (LH) per City code. The report further states that the eastern portion of the site meets the criteria for a Low Erosion Hazard (EL) and the western portion of the site meets the criteria of a High Erosion Hazard (EH). The area of the site that is mapped as a high erosion hazard will not be developed. The report states that the portion of the site that will be developed should have erosion control measures as outlined in the report. Based on the results of the subsurface explorations and slope stability analysis, the report concludes that the proposal will not increase the threat of the geological hazard to adjacent or abutting properties beyond predevelopment conditions or adversely impact other critical areas. The proposed townhomes have been designed to step down with the existing topography and the majority of the development is on the least sensitive area of the site. To assess the stability of the slopes in the western portion of the site, a slope reconnaissance was performed by RGI on November 13, 2018. The report states that the western portion of the site is occupied DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2 City of Renton Department of Community & Economic Development VEK on Aberdeen Townhomes Plat Staff Report to the Environmental Review Committee LUA19-000280, PP, SA-A, ECF, MOD, MOD, MOD, Report of April 5, 2021 Page 5 of 11 SR_ERC_Report_VEK on Aberdeen Townhomes (002) by a drainage that descends west to John Creek, near the western property line. The drainage originates on the property to the north, and the head of the drainage is occupied by a detention tank overflow comprised of a 12-inch Drisco pipe and spillway constructed of gabion cages and quarry spalls. According to the report, the drainage appears to have intermittent flow, with native, glacially consolidated soils exposed along the channel and lower slope areas. Soils are generally silty sand in the upper drainage, with silt occupying the channel around the 135-foot elevation. Light seepage was observed by RGI along the sand/silt contact in the southern bank of the channel, consistent with seasonal perched groundwater collecting above the generally impermeable silt. Trees with curved trucks were observed that are indicative of surficial creep, however, the report states that the slopes are well vegetated with trees that do not appear to be effected by large-scale movements. Exposed soils at and near the base of the drainage are indicative of moderate erosion at the toe of the slope during the wetter winter months. The report concluded that the proposed development can be safely accommodated on the site, and no additional slope setback, beyond what is required by City code, was recommended for the project. The proposed structures, as currently shown, would comply with the protected slope setbacks. The project proposes to emulate the existing site drainage patterns for the developed stormwater runoff. An above-ground tightline system, designed to convey stormwater runoff from the developed portion of the site, over the onsite steep slopes, is proposed to meet this requirement. The proposed tightline system would discharge flows at a location nearby John’s Creek and outside of the sloped areas and wetland buffers. The report states that the storm pipe is an HDPE above-ground pipe anchored on the surface that does not required modification of the slope. The report further states that stability analysis of the slope indicates stable conditions and the pipe installation should have no impact on the stability of the slopes. Per RMC 4-3-050C.3.12, installation of new storm drainage lines in any geologic hazard area is permitted with a Critical Area Letter of Exemption when a geotechnical report clearly demonstrates that the installation would comply with the criteria listed in RMC 4-3-050.J.1, criteria for modifying geologically hazardous area standards, and that the installation would be consistent with each of the purposes of the critical area regulations listed in RMC 4-3-050.A. Also, to qualify for the exemption, the report must propose appropriate mitigation for any potential impacts identified in the report. The applicant submitted a Geotechnical Engineering Report, prepared by The Riley Group, Inc. (RGI), dated November 27, 2018, and subsequently revised on September 2, 2020 (Exhibit 11), with the project application. The applicant also submitted a supplemental letter from The Riley Group, Inc., dated April 23, 2020 (Exhibit 14), in response to staff comments regarding the steep slopes. The letter states that RGI completed a stability analysis for the currently proposed conditions and proposed drainage facilities. Based on the stability analysis, RGI did not recommend additional buffers for the steep slopes. In addition, RGI concluded that the proposal was feasible from a geologic perspective and did not recommend further mitigation for the proposed above ground drainage lines within the geologic hazardous areas. Independent secondary review was completed for the subject project in accordance with RMC 4-3-050F.6. GeoEngineers prepared a Geotechnical Engineering Review analysis of the proposed project, dated October 15, 2020 and October 30, 2020 (Exhibit 15), in response to RGI’s engineering review. GeoEngineers concluded that the project can be constructed generally as envisioned without causing undue risk to the public provided that the recommendations in the project geotechnical report are incorporated into the design and followed during construction. The applicant indicated that the estimated quantities of cut on-site would be approximately 261 cubic yards and the estimated quantities of fill would be 983 cubic yards. A total of 722 net cubic yards of fill is proposed for the development. According to the report, building foundations can be supported on conventional spread footings bearing on medium dense to dense native soil or structural fill. Slab-on- grade floors and pavements can be similarly supported. If loose, organic, or other unsuitable soils are encountered, RGI recommends that the site be over-excavated and backfilled with structural fill. According to the report, the site soils are moisture sensitive and may require moisture conditioning prior to use as structural fill. DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2 City of Renton Department of Community & Economic Development VEK on Aberdeen Townhomes Plat Staff Report to the Environmental Review Committee LUA19-000280, PP, SA-A, ECF, MOD, MOD, MOD, Report of April 5, 2021 Page 6 of 11 SR_ERC_Report_VEK on Aberdeen Townhomes (002) Grading would be required for the construction of proposed plat improvements and new multi-family residences (Exhibit 10). Erosion control measures would need to be in place prior to starting grading activities on the site. Temporary erosion and sedimentation control measures would be implemented during construction including, but not limited to, Best Management Practices (BMPs) and temporary measures to control surface water runoff and groundwater during construction, such as retaining existing vegetation whenever feasible, establishing a quarry spall construction entrance, installing siltation control fencing or anchored straw or coir wattles on the downhill side of the work areas, covering soil stockpiles with anchored plastic sheeting, and confining sediment to the project site. The provided geotechnical report concluded that the construction of the proposed residential development is feasible from a geotechnical standpoint. The primary geotechnical considerations submitted in the geotechnical report included field exploration and laboratory testing, site conditions, discussion and recommendations, additional services, and limitations. The study provides recommendations related to erosion control and excavation. Due to the project site’s location within a geologic hazard areas, staff recommends as a SEPA mitigation measure that project construction comply with the recommendations found in the Geotechnical Report prepared by The Riley Group, Inc. (dated September 2, 2020) for the proposed Unit Lot Subdivision, or updated reports submitted at a later date. Mitigation Measures: a. Project construction shall comply with the recommendations found in the Geotechnical Report prepared by The Riley Group, Inc. (dated November 27, 2018) for the proposed Unit Lot Subdivision, and any updated report(s) associated with the building and construction permits to ensure compliance with the intent of the initial report. b. The applicant’s geotechnical engineer shall review the project’s construction and building permit plans to verify compliance with the geotechnical report(s). The geotechnical engineer shall submit a sealed letter stating that he/she has reviewed the construction and building permit plans and in their opinion the plans and specifications meet the intent of the report(s). Nexus: SEPA Environmental Review, City of Renton Comprehensive Plan Policy L-36, RMC 4-3-050 Critical Areas Regulations 2. Air Impacts: It is anticipated that some short-term air quality impacts could be associated with site work and building construction required to develop this site. Project development impacts during construction may include dust as a result of grading and exhaust from construction vehicles and equipment. Dust control would be mitigated through the use of temporary erosion control measures, watering or other measures to remediate impacts as needed (Exhibit 13). Long-term impacts would result from the net increase of vehicle emissions from resident’s cars. Electric fireplaces are proposed within the units. Mitigation Measures: No further mitigation is recommended. Nexus: Not applicable. 3. Water a. Wetland, Streams, Lakes Impacts: The applicant submitted a Critical Areas Study, prepared by Beaver Creek Environmental Services, Inc., dated August 18, 2018, with the project application, which was later revised on October 16, 2020 (Exhibit 16). The site visit was conducted by Beaver Creek Environmental Services on June 21, 2018 and again on February 13, 2020. A combination of field indicators, including: soils, vegetation, and hydrology, were used to determine whether wetlands were present on the subject lot. DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2 City of Renton Department of Community & Economic Development VEK on Aberdeen Townhomes Plat Staff Report to the Environmental Review Committee LUA19-000280, PP, SA-A, ECF, MOD, MOD, MOD, Report of April 5, 2021 Page 7 of 11 SR_ERC_Report_VEK on Aberdeen Townhomes (002) According to the report, a small (541 square foot) wetland was identified on the west portion of the site. The report states that no other wetlands were observed within sight distance of project boundaries. The wetland identified on site was located in the western portion of the site and offsite along the west boundary. The wetland is associated with the drainage. The drainage course flows approximately through the center of the site going west. Hydrology for this wetland was provided by surface ponding of storm water and runoff from drainage flowing through the wetland. According to the report, Wetland A meets the criteria for a Category III wetland, with 4 Habitat Points. This wetland requires a standard 75-foot buffer and a 15-foot building setback beyond the buffer when adjacent to non-low impact land uses per RMC 4-3-050.G.2. The edge of the wetland is mapped more than 270 feet from the edge of nearest developed area (Tract D) for the proposed development, which exceeds buffer requirements. City GIS Maps identified a tributary to Johns Creek transecting the west portion of the site, confluencing with Johns Creek near the west boundary of the property. The report states that the stream was observed to be an unnatural drainage ditch, which as stated in the report, transects the site from the center of the north boundary to the west boundary, through the center of the site. This drainage originates at a detention pond on the parcel adjacent offsite to the north, which drains through a 12-inch culvert to the head of the drainage. The report states that the drainage is deeply incised and actively eroding. The report states that the streams on the site do not meet the criteria for definition as a Type Ns stream. The report clarifies that the water source is “unnatural” in that it is derived from a stormwater system on the parcel to the north which focuses flow and forces it to the drainage course. This water is diverted from the stream to the north into the on-site drainage. The report further states that substantial erosion indicates a recent change in flow regime is altering the stream morphology. The stream flows west from the site to a culvert under I-405. The drainage flows approximately 340 feet in the culvert, daylighting on the west berm of I-405, and flows immediately into the stormwater sewer system. The storm drain flows south for 1,000 feet, then west 1,000 feet south of Fry’s Electronics, then north 2,000 feet, daylighting again at the north berm of Southport Drive. The report concludes that, because this drainage traverses over 4,000 feet in the underground stormwater system, it is not “physically connected by an above-ground channel system to Type S, F, or Np Waters.” Because of these considerations, the report states that the drainage does not meet the criteria for regulation as a typed stream. However, per City GIS Maps, Johns Creek is identified as a type Ns Stream. Per RMC 4-3-050E.5.a, the reclassification of a water body to a lower class requires Administrator acceptance of a stream or lake study, followed by a legislative amendment to the map in subsection E of RMC 4-3-050 prior to its effect. Therefore, while the critical area study states that the streams on site do not meet the definition of a Type Ns stream, the streams would be regulated as Type Ns streams unless a legislative amendment was requested and approved. City code requires a stream buffer of 50 feet, with a 15-foot building setback beyond the buffer, for type Ns streams. However, per footnote 5 of RMC 4-3-050G.2, when a required stream buffer falls within a protected slope, the stream buffer width shall extend to the boundary of the protected slope. The streams on site are located within the protected slope; therefore, the edge of the stream buffer would extend to the edge of the protected slope. The proposed structures and open space (Tract D), as currently shown, comply with the stream buffer and building setback requirements. An above-ground tightline system, designed to convey stormwater runoff from the developed portion of the site, over the onsite steep slopes, is proposed within the existing stream and wetland buffer. The report states that the proposed homesites and associated utilities were designed to avoid adversely impacting the identified onsite wetlands and stream. The report clarifies that, because of the precipitous nature of the site, collected stormwater must be released where the stream channel gradient diminishes. Stormwater will be transported to the Rock-lined Pipe Discharge Protector by elevated pipe. The pipe traverses 168 feet of wetland buffer to the 50 square foot Discharge Protector. DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2 City of Renton Department of Community & Economic Development VEK on Aberdeen Townhomes Plat Staff Report to the Environmental Review Committee LUA19-000280, PP, SA-A, ECF, MOD, MOD, MOD, Report of April 5, 2021 Page 8 of 11 SR_ERC_Report_VEK on Aberdeen Townhomes (002) This results in a permanent impact to the wetland buffer of 268 square feet. The report states that this encroachment into the identified buffer for the on-site wetlands is required to establish the home sites. Per RMC 4-3-050.C.4, a Critical Areas Letter of Exemption may be issued for necessary conveyance systems including stormwater dispersion outfall systems designed to minimize impacts to the wetland and stream buffer and critical area, where the site topography requires their location within the buffer to allow hydraulic function provided the standard buffer zone area associated with the critical area classification is retained pursuant to RMC 4-3-050.G.2, and the conveyance system is sited to reduce impacts between the critical area and surrounding activities. A Wetland Buffer Mitigation Plan prepared by Beaver Creek Environmental Services, Inc., dated February 22, 2021 (Exhibit 16), was submitted in response to staff comments. The mitigation plan states that, per the revised Geotechnical Engineering Report prepared by the Riley Group (Exhibit 11), stormwater directed toward the downstream steep slope must be piped in a closed conduit installed on the slope face and discharged beyond the toe of the slope. Therefore, the proposed outfall location was selected in order to allow the tightline stormwater pipe to discharge beyond the toe of slope, where grades are less than 15%. In addition, the proposed tightline stormwater pipe alignment was selected in order to avoid disturbance of all protected significant trees within the Critical Area Tract. In order to connect the required tightline system to the outfall location with minimal disturbance of significant trees, the stormwater pipe must parallel the stream for a short portion of the alignment. The mitigation plan concludes that the proposal avoids paralleling the stream to the maximum extent feasible, while still meeting Critical Area Tract tree retention requirements and the storm discharge location requirements of the Geotechnical Engineer of Record. The Mitigation Plan states that the goal of the mitigation proposal is to fully compensate for the unavoidable adverse impact to regulated buffer areas. The plan further states that upon the completion of the mitigation plan there will be no net loss of wetland acreage, functions, or values; and an increase in the potential for the buffer to protect aquatic habitats. The proposal includes removal of invasive species and buffer enhancement planting. Staff will recommend a condition of approval to the Hearing Examiner to obtain a final detail mitigation plan prior to Civil Construction Permit issuance. Mitigation Measures: No further mitigation recommended. Nexus: N/A b. Storm Water Impacts: The applicant submitted a Preliminary Technical Information Report, prepared by Encompass Engineering & Surveying, dated October 31, 2019, with the project application, which was later revised on December 11, 2020 (Exhibit 9). The development is subject to Full Drainage Review in accordance with the 2017 City of Renton Surface Water Design Manual (RSWDM). All nine (9) core requirements and all six (6) special requirements were discussed in the Technical Information Report. Per the Flow Control Application Map in the 2017 City of Renton Surface Water Design Manual, the project site is within the Peak Rate Flow Control Standard area matching Existing Site Conditions and is within the East Lake Washington Drainage Basin. In this area, flow control facilities are required to match the existing conditions 2-, 10-, and 100-year peak-rate runoff from the site. The applicant is proposing a stormwater detention tank located on the western edge of the unit lot driveway, designed per Section 5.1.2 of the RSWDM, that would be utilized to mitigate all developed onsite and offsite stormwater flows for the project. An Oldcastle Biopod filtration device is proposed to provide for enhanced water quality treatment. The existing site drains to a low point in the form of a vegetated drainage channel, which discharges to the western edge of the property and it is conveyed off-site under I-405. The project proposes to emulate the existing site drainage patterns for the developed stormwater runoff. An above-ground tightline system, designed to convey stormwater runoff from the developed portion of the site, over the onsite steep slopes, is proposed to meet this requirement. DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2 City of Renton Department of Community & Economic Development VEK on Aberdeen Townhomes Plat Staff Report to the Environmental Review Committee LUA19-000280, PP, SA-A, ECF, MOD, MOD, MOD, Report of April 5, 2021 Page 9 of 11 SR_ERC_Report_VEK on Aberdeen Townhomes (002) The proposed tightline system would discharge flows at a location nearby John’s Creek and outside of the 15 percent sloped areas. The proposed development is considered by the City of Renton to be in order with the “Large Lot” project type. Due to steep slopes, landslide and erosion hazard areas being located onsite, full dispersion, full infiltration, limited dispersion, limited infiltration, bioretention and permeable pavement are all infeasible. Specifically, Section 1.2.9.2.2 (5) of the 2017 RSWDM states: ‘The buildable portion of the site/lot is the total area of the site/lot minus any critical areas and minus 200 ft. buffer areas from a steep slope hazard, landslide hazard, or erosion hazard area’. For the applicability of BMP’s, the 200 ft. buffer encompasses the entire site, therefore, per definition, there are no onsite buildable areas subject to BMP’s. The applicant will be required to submit a final TIR and drainage plan that includes all the details of the Flow Control facility analysis, water quality analysis, and conveyance analysis in compliance with the requirements of RSWDM, for review and approval by Development Engineering at the time of construction permit application. It is anticipated that the City’s currently adopted 2017 City of Renton Surface Water Design Manual would mitigate for any potential surface water impacts that could be generated by the project proposal, therefore no further mitigation is recommended at this time. Mitigation Measures: No further mitigation is recommended. Nexus: Not applicable. 4. Vegetation Impacts: An Arborist Report, prepared by Shoffner Consulting, and subsequently revised on January 11, 2021, was submitted with the land use application (Exhibit 7). The Arborist Report identified a total of ninety (90) on-site, significant trees on the subject property. A total of fifty-six (56) significant trees are located within the proposed critical area tract. All trees within the proposed critical area tract are proposed to be retained. A total of thirty-four significant trees are located within the developable portion of the property, of which the applicant is proposing to retain five (5) trees. A total of twenty-nine (29) trees are proposed for removal as part of the project proposal. The minimum tree retention requirement is twenty percent (20%) in the Residential Multi-Family (RMF) zone after deductions. Certain trees are excluded from retention calculations, including dangerous trees, trees in proposed public streets, trees in proposed private access easements/tracts, and trees in critical areas and critical area buffers. The tree retention worksheet (Exhibit 5) identifies a total of 4 trees within the proposed private access tract. Following the deduction of trees within critical area and access tracts, the applicant is required to retain a total of six (6) tree to comply with minimum tree retention requirements . The applicant proposes a replacement planting of 12 caliper inches to replace the protected tree removed. Staff will address compliance with minimum tree retention regulations and tree replacement at the time of Site Plan review and recommend a condition of approval to address concerns regarding landscaping and tree replacement prior to construction permit approval. Mitigation Measures: No further mitigation is recommended. Nexus: Not applicable. 5. Environmental Health a. Noise Impacts: Noise impacts would primarily result from the clearing of the site, construction of the proposed infrastructure improvements and future construction of the new multi-family residences. The construction and construction equipment noise would be regulated through the City’s adopted noise level regulations per Chapter 8-7, RMC, Noise Level Regulations and RMC 4-4-030. The City’s DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2 City of Renton Department of Community & Economic Development VEK on Aberdeen Townhomes Plat Staff Report to the Environmental Review Committee LUA19-000280, PP, SA-A, ECF, MOD, MOD, MOD, Report of April 5, 2021 Page 10 of 11 SR_ERC_Report_VEK on Aberdeen Townhomes (002) construction standards limit haul hours between 8:30 am to 3:30 pm, Monday through Friday unless otherwise approved by the Development Services Division. Permitted work hours in or near residential areas are restricted to the hours between 7:00 am and 8:00 pm for new construction activities from Monday through Friday. Work on Saturdays is restricted to the hours between 9:00 am and 8:00 pm. No work is permitted on Sundays. Temporary noise impacts are anticipated that would be commonly associated with new multi-family residential development. Mitigation Measures: No further mitigation is recommended. Nexus: Not applicable. 6. Aesthetics Impacts: The applicant submitted building elevations, prepared by Monsef Design Studio, dated November 6, 2019 (Exhibit 8), with the project application. Based on the provided elevations, the proposed structures step down with the topography of the site. Based on street view, it is not anticipated that the design of the proposed units will be inconsistent with the surrounding neighborhood. In addition, due to the existing vegetation on site, it is not anticipated that the proposed structures will be impactful to views for the abutting residents across the street. Mitigation Measures: No further mitigation is recommended. Nexus: Not applicable. 7. Transportation Impacts: The project site fronts Aberdeen Ave NE along the east property line (Exhibit 2). All vehicular access to the project would be from Aberdeen Ave NE via a 21-foot wide unit lot drive that runs along the north side of the development (Tract B). No parking is allowed in the unit lot drive. Aberdeen Ave NE is classified as a Collector Arterial Road. Existing right-of-way (ROW) width is approximately 60 feet. To meet the City’s complete street standards for Collector Arterial streets, a minimum ROW of 83 feet is required, which would require a dedication of 20.5 feet of ROW for the proposed project. Per RMC 4-6-060, half street improvements shall include a pavement width of 46 feet (23 feet from centerline), a 0.5-foot curb, an 8-foot planting strip, an 8-foot sidewalk, street trees and storm drainage improvements. The applicant is requesting a street modification (Exhibit 17) for cross section changes to the Aberdeen Ave NE frontage improvements, to allow for a 6-foot wide planter strip and 5-foot wide sidewalk, resulting in a 4.5-foot ROW Dedication (pending final survey) in lieu of the full half street standards. A Traffic Technical Memo (Exhibit 18) was submitted with the project application. According to the memo, approximately 5.5 vehicle trips are anticipated in the AM peak hours and approximately 6.7 vehicle trips are anticipated in the PM peak hours. Per the City of Renton Traffic Impact Analysis Guidelines, a traffic impact analysis (TIA) is required when estimated vehicular traffic generated from a proposed development exceeds 20 vehicles per hour during either the AM (6:00 – 9:00) or PM (3:00 – 6:00) peak periods as determined by a Trip Generation Report. Based on the proposed 12-lot unit lot subdivision, a TIA would not be required for this project because the development would not exceed the 20 vehicle trips in the AM or PM peak periods. It is not anticipated that the proposed project would adversely impact the City of Renton’s street system subject to the payment of code-required impact fees and the construction of code-required frontage improvements. The transportation impact fee, as determined by the Renton Municipal Code at the time of building permit issuance shall be payable to the City. A concurrency recommendation would be provided in the staff report to the Hearing Examiner based upon the test of the citywide Transportation Plan, consideration of growth levels included in the LOS‐ tested Transportation Plan, payment of a Transportation Mitigation Fee, and an application of site specific mitigation. The development would have to meet the City of Renton concurrency requirements. DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2 City of Renton Department of Community & Economic Development VEK on Aberdeen Townhomes Plat Staff Report to the Environmental Review Committee LUA19-000280, PP, SA-A, ECF, MOD, MOD, MOD, Report of April 5, 2021 Page 11 of 11 SR_ERC_Report_VEK on Aberdeen Townhomes (002) Mitigation Measures: No further mitigation is recommended. Nexus: Not applicable. 8. Fire & Police Impacts: A minimum of five (5) fire hydrants are required for this project. Police and Fire Prevention staff indicated that sufficient resources exist to furnish services to the proposed development subject to the construction of code-required improvements and the payment of code-required impact fees (Exhibit 19). Mitigation Measures: No further mitigation is recommended. Nexus: Not applicable. E. Comments of Reviewing Departments The proposal has been circulated to City Department and Division Reviewers. Where applicable, their comments have been incorporated into the text of this report and/or “Advisory Notes to Applicant.” ✓ Copies of all Review Comments are contained in the Official File and may be attached to this report. The Environmental Determination decision will become final if the decision is not appealed within the 14-day appeal period (RCW 43.21.C.075(3); WAC 197-11-680). Environmental Determination Appeal Process: Appeals of the environmental determination must be filed in writing on or before 5:00 p.m. on April 19, 2021. Due to Governor Jay Inslee’s Proclamation 20-25 (“Stay Home, Stay Healthy”), the City Clerk’s Office is working remotely. For that reason, appeals must be submitted electronically to the City Clerk at cityclerk@rentonwa.gov. The appeal fee, normally due at the time an appeal is submitted, will be collected at a future date. Appeals to the Hearing Examiner are governed by RMC 4-8-110 and additional information regarding the appeal process may be obtained from the City Clerk’s Office, cityclerk@rentonwa.gov. If the situation changes such that the City Clerk’s Office is open when you file your appeal, you have the option of filing the appeal in person. DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2 CITY OF RENTON DEPARTMENT OF COMMUNITY AND ECONOMIC DEVELOPMENT STAFF REPORT TO THE ENVIRONMENTAL REVIEW COMMITTEE EXHIBITS Project Name: VEK on Aberdeen Townhomes Plat Land Use File Number: LUA19-000280, PP, SA-A, ECF, MOD, MOD, MOD Date of Meeting April 5, 2021 Staff Contact Angelea Weihs Associate Planner Project Contact/Applicant Nicole Mecum, PE, Encompass Engineering and Surveying 165 NE Juniper St., Suite 201, Issaquah, WA 98027 Project Location 957 Aberdeen Ave NE The following exhibits are included with the ERC Report: Exhibit 1: Environmental Review Committee (ERC) Report Exhibit 2: Site Plan Exhibit 3: Neighborhood Detail Map Exhibit 4: Unit Lot Subdivision Plat Map Exhibit 5: Landscape Plan and Tree Retention Worksheet, prepared by Cramer Design Consultants, Inc., dated June, 13, 2019 Exhibit 6: Tree Retention Plan, prepared by Cramer Design Consultants, Inc., dated December 11, 2020 Exhibit 7: Arborist Report, prepared by Shoffner Consulting, dated January 11, 2021 Exhibit 8: Design Review Package with Floor Plans and Building Elevations, prepared by Monsef Design Studio, dated December 11, 2020 Exhibit 9: Preliminary Technical Information Report, prepared by Encompass Engineering & Surveying, dated December 11, 2020 Exhibit 10: Civil Plan Set (Cover Sheet, Preliminary Grading & Drainage, Preliminary Sewer & Water Plan, Street Profile and Cross Sections), prepared by Encompass Engineering & Surveying, dated December 11, 2020 Exhibit 11: Geotechnical Engineering Report, prepared by The Riley Group, Inc., dated September 2, 2020 Exhibit 12: Environmental Checklist Exhibit 13: Construction Mitigation Description Exhibit 14: Supplemental letter from The Riley Group, Inc., dated April 23, 2020 Exhibit 15: Secondary Geotechnical Engineering Review letters, prepared by GeoEngineers, dated October 15, 2020 and October 30, 2020 Exhibit 16: Critical Area Designation, prepared by Beaver Creek Environmental Services, Inc., dated October 16, 2020, and Wetland Buffer Mitigation Plan prepared by Beaver Creek Environmental Services, Inc., dated February 22, 2021 Exhibit 17: Street Modification Request Exhibit 18: Traffic Technical Memo Exhibit 19: Advisory Notes DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2