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Home My WebLink AboutD - As-built Report CT 2016-12A S -BUILT R EPORT Canyon Terrace Subdivision Wetland and Buffer Mitigation Project, Wetland and Stream As-Built Report Prepared for: Bryan White Summit Homes 16000 Christensen Road, Ste. 303 Tukwila, WA 98188 Prepared by: December 7, 2016 The Watershed Company Reference Number: 140121 The Watershed Company Contact Person: Nell Lund, PWS Cite this document as: The Watershed Company. December 2016. Canyon Terrace Wetland and Buffer Mitigation Project, Wetland and Buffer Restoration As-built Report. The Watershed Company December 2016 i T ABLE OF C ONTENTS Page # 1 Background Information .................................................................... 1 1.1 Project Name ................................................................................................... 1 1.2 Project Permits and Reference Numbers ...................................................... 1 1.3 As-Built Report Authors and Project Contacts ............................................. 1 1.4 Report Date ...................................................................................................... 2 2 The Compensatory Mitigation Project .............................................. 2 2.1 Final Mitigation Project Summary .................................................................. 2 2.2 Mitigation Acreage and Types ........................................................................ 3 2.3 As Built Summary and Important Dates ........................................................ 4 3 Problems Encountered/Solutions Implemented .............................. 6 4 Follow-up Actions ............................................................................... 6 5 Conclusion .......................................................................................... 7 L IST OF F IGURES Figure 1. Vicinity map. ..................................................................................................... 2 L IST OF T ABLES Table 1. Total acreage and types of mitigation authorized to compensate for wetland impacts. ................................................................................................... 3 A PPENDICES Appendix A – As-built plan set Appendix B – As-built photos/Permanent photo-stations Appendix C – Plant counts/Documentation The Watershed Company December 2016 A S -BUILT R EPORT CANYON TERRACE WETLAND AND WETLAND BUFFER MITIGATION 1 BACKGROUND INFORMATION 1.1 Project Name The name of the project for which this As-Built report documents is Renton Canyon Terrace. 1.2 Project Permits and Reference Numbers • Corps Nationwide Permit 12, Ref. No. NWS-2014-847 • City of Renton Land Use Application, Ref. No. LUA-13-000840 • The Watershed Co. Ref. No. 140121 1.3 As-Built Report Authors and Project Contacts The as-built report authors from The Watershed Company are: Ecologist, Nell Lund, PWS and Ecologist Jasmine Palmer, WPIT. Nell Lund is the project manager and was the primary wetland professional on site during construction of the compensatory mitigation site. She corresponded with the applicant, Bryan White, Summit Homes, and the site construction supervisor over the course of mitigation project installation. Parcels 3323059-010 and -057 are owned by King County Parks. Parcels 6199000-101 and -260 are owned by Summit Frenchies LLC. Primary As-Built Report Author: Nell Lund, PWS The Watershed Company 750 6th St South Kirkland, WA 98033 (425) 822-5242 Wetland Professional On-Site: Nell Lund, PWS Applicant: Bryan White, Summit Homes Landowners: King County Parks, Summitt Frenchies LLC Renton Canyon Terrace Wetland and Wetland Buffer Mitigation As-built Report 1.4 Report Date This As-Built Report was produced on December 7, 2016. 2 THE COMPENSATORY MITIGATION PROJECT 2.1 Final Mitigation Project Summary Project Location The mitigation project is located along the upper reach of Soos Creek within Renton, Washington, located at 18801 124th Ave SE and the adjacent parcels to the east and south in the City of Renton (parcels 332305-9010, -9057 and 619900-0101, -0260. The Canyon Terrace Subdivision Mitigation site can be accessed from either SE 188th St, east of the intersection of 120th Ave SE and SE 188th St or the intersection of SE 192nd St and 124th Ave SE. Figure 1. Vicinity map. Approved Plan (Revised Permit Set, October 24, 2014) This mitigation project is for a 70 lot subdivision spanning four parcels (619900-0101, - 0240, -0241, and -0260); utility improvements will extend into adjacent parcels 332305- Approximate Project Area The Watershed Company December 2016 9010 and -9057, and the 124th Avenue SE right-of-way will be improved for site access. The subdivision and short-plats were vested in 2004 and approved by King County in 2006 and 2007 (Reference Numbers L04P0002, L05S0040, and L04P0027), prior to annexation into City of Renton. The adjacent Soos Creek wetland was identified during the subdivision/plat approval process; the site is vested to a 100-foot wetland buffer. The project will incur unavoidable wetland and wetland buffer impacts. Direct wetland impacts will be temporary in nature and are required to install a sewer connection to an existing line. Permanent wetland buffer impacts will be generated by right-of-way improvements and stormwater outfalls. Associated grading will cause temporary buffer impacts. Mitigation Acreage and Types The proposed mitigation plan fulfills the requirements of City of Renton under RMC 4- 8-120. All temporary and permanent wetland and wetland buffer impacts require mitigation; mitigation areas and actions are summarized in Table 1 below. All proposed mitigation actions will occur at the impact sites and within the adjacent NGPA tract as shown on this mitigation plan set. Table 1. Total acreage and types of mitigation authorized to compensate for wetland impacts. Impact Area Mitigation Type/Action Area Ratio 12,960 SF Buffer replacement/addition 19,000 SF 1.47:1 36,750 SF* Buffer restoration, in-place 36,750 SF* 1:1 3,000 SF Wetland restoration, in-place 3,000 SF 1:1 * The buffer planting area was increased by approximately 3,400 SF beyond the planned 36,750 SF to account for additional buffer disturbance incurred during construction. To mitigate for permanent buffer impacts, buffer replacement and addition occurred at a 1.47:1 ratio. Permanent buffer impacts were primarily due to road construction and stormwater improvements. To account for buffer fragmentation and associated loss of functions, small buffer pieces west of the new road (3,250 SF total) were tabulated as buffer loss and accounted for in the buffer replacement figure. The proposed buffer addition area was previously vegetated by emergent plants and small shrubs; it is within the BPA corridor. To mitigate for temporary buffer impacts, in-place buffer restoration occurred at a 1:1 ratio. Where temporary grading impacts overlap with the future Soos Creek Trail footprint, restoration was limited to application of a grass seed mix. Since that area will ultimately impacted by trail construction, further planting in the trail footprint was not practical. The remainder of the temporary buffer impact area was planted with native trees, shrubs, and groundcover plants. Restoration in the BPA corridor was limited to Renton Canyon Terrace Wetland and Wetland Buffer Mitigation As-built Report shrubs and groundcover plants due to vegetation height restrictions in the transmission line corridor. Temporary wetland impacts were mitigated through in-place restoration. Following pipe installation, the excavated area was back-filled with wetland soil. Following the vegetation height restrictions for the transmission line corridor, vegetation in the disturbed area was restored. Restoration within the future Soos Creek Trail footprint (a King County-Parks project) was limited to grass seed mix. The restoration provides a compensatory level of protection for the critical area and offsets the disturbance associated with modification off the wetland and standard wetland buffer. Changes During Construction As noted on Table 1 above, the buffer planting area was increased by approximately 3,400 SF beyond the planned 36,750 SF to account for additional buffer disturbance incurred during construction. The additional impacts were the result of a storm event and improper stockpiling of woodchips. To account for these unplanned temporary buffer impacts, those areas were restored and enhanced in-place with 41 trees, 95 shrubs, and 214 groundcover plants per recommendation of Ecologist Nell Lund. Minor changes in plant species quantities installed occurred due to plant availability and changes made to the JARPA plan set in response to Snoqualmie Tribe comments. Sweet gale (Myrica gale) and high bush cranberry (Viburnum trilobum) were added to the plant species within the wetland restoration area. 2.2 As Built Documentation and Important Dates September 2015 • Corps permit received and sewer line extension construction initiated. January 2016 • Compensatory mitigation construction initiated. February 5, 2016 • Additional temporary buffer impacts, approximately 3,400 SF total, noted due to unanticipated storm event, temporary erosion control measures, and former stockpiling of woodchips. • Some buffer plants installed, but some planting areas yet ready. Temporary erosion controls, including plastic sheeting, covers some buffer planting areas. • Wetland topsoil is stockpiled outside the critical area for future placement in the sewer line disturbance area. The Watershed Company December 2016 July 8, 2016 • Wetland soil placement in the sewer line area verified. Soils and grade in the sewer line disturbance area were examined and appear to be restored to a pre- construction condition. • Plants had been ordered plants from the City-permit plan set, which differed slightly in this area from the Corps-submitted plan set. The delivery contained 98 plants; it was 10 plants short of needed totals and lacked two of the species from the Corps plan set. To reconcile this difference, 10 more plants were obtained: 5 x wax myrtle and 5 x high bush cranberry. • Obtained plants were stockpiled in an irrigated area while grading and soil preparation was reviewed. • A temporary erosion control measures removed as permitted by city-review. • The north buffer addition and enhancement area appeared to have been tied into the surrounding grade. • Temporary irrigation had been installed in planting areas. • A car had recently drove off-road into the mitigation area, near the detention pond. Some of the plantings were damaged and the area was replanted (replanting noted on July 29, 2016). July 21 and 29, 2016 • The north buffer addition area had been planted and temporary irrigation was in-place. The area around the north gabion outfall was been planted. Planting was completed per plan. • Plants were installed in the area disturbed by an off-road car. November 7, 2016 • The buffer and sewerline mitigation areas are all planted. Previously stockpiled plants had been installed in the western edge of sewer line restoration area. All tree, shrub and groundcover planting appeared to be per plan. • Hydroseeded plants in the wetland creation area had not established due to water flow washing seeds away before rooting. According to the landscape contractor, the custom emergent seed mix was applied to the wetland restoration area with a tackifier twice, but it washed away both times. • Split rail fencing had been installed around the mitigation areas. • Transects and photo points were established and as-built baseline conditions were recorded by TWC ecologists (see section 2.3 below). December 1, 2016 • Critical Area signage added to split-rail fencing (photo documentation provided by client via email). Renton Canyon Terrace Wetland and Wetland Buffer Mitigation As-built Report 2.3 Monitoring Stations Five 100-foot transects were established across the mitigation areas. Transect locations are documented on sheets W3 and W4 of the As-Built plan set (see Appendix A). Photos were taken at transect ends and baseline plant counts were noted along transects for monitoring plant survival in future years (see Appendices B and C). To further document site conditions, five photo points were set up within the mitigation site. As- built photo point photos are documented in Appendix B and photo point locations are documented on sheets W3 and W4 of the As-Built plan set. 3 PROBLEMS ENCOUNTERED/SOLUTIONS IMPLEMENTED Problem Encountered Solution Implemented Unanticipated erosion, erosion control measures, and woodchip stockpiling caused additional temporary disturbance to the wetland buffer. Disturbed areas (approximately 3,400 SF of additional buffer area) were restored with additional plantings. Car crashed through mitigation area, damaging some installed plants. Plants were replaced as needed. Hydroseeded plants in the wetland creation area had not established due to water flow washing seeds away before rooting even though a tackifier was used. Reapply hydroseeded with a tackifier in late- spring/early-summer, then water levels are low. 4 FOLLOW-UP ACTIONS AND RECOMMENDATIONS The final actions still necessary to occur for completing the As-Built requirements are to: • Establish hydroseeded emergent vegetation in the wetland restoration area through re-hydroseeding with a tackifier in a drier period. Late spring or early summer application timing recommended. Based on site conditions and in accordance with required maintenance in the mitigation plan, the following is also recommended: The Watershed Company December 2016 • Periodically check irrigation system for breaks and to ensure that enough water is provided to promote plant growth, • Consistent removal of invasive plant species, including those listed by the King County Noxious Weed Control Board, • Conduct regular weeding throughout all planted areas and remove competitive plant species from the base of mitigation plants, and • Refresh mulch when needed. 5 CONCLUSION Installation of the approved mitigation plan is substantially complete and was implemented with only minor deviations from the original plans. The custom emergent seed mix will need to be reapplied to the wetland restoration area in a dry period in spring/summer of 2017. Additional temporary buffer disturbance was restored in-place with native trees, shrub, and groundcover plants and total plant quantities were increased accordingly. With ongoing maintenance and annual monitoring as prescribed in the Mitigation Plan (see Appendix B), it is anticipated that the installed plant material will be sufficient to colonize the project. Such maintenance activities required successful establishment of mitigation plantings are anticipated to include plant replacement, weeding, watering, mulching, and other activities. The Watershed Company December 2016 A PPENDIX A As-Built Plan Set The Watershed Company December 2016 A PPENDIX B As-Built Photos Renton Canyon Terrace Wetland and Wetland Buffer Mitigation As-built Report C ONSTRUCTION M ONITORING PHOTOS Photo 1. Looking west from east end of sewer line extension. (Photo Taken 2/5/16) Photo 2. Looking east from west end of sewer line extension. (Photo Taken 2/5/16) The Watershed Company December 2016 Photo 3. Facing south from NE corner of detention pond area. Shows an area of additional buffer disturbance that was later restored. (Photo taken 2/5/16) Photo 3. Wetland soil replaced, grade restored. (Photo taken 7/8/16) Renton Canyon Terrace Wetland and Wetland Buffer Mitigation As-built Report Photo 4. Wetland restoration planting. (Photo taken 7/21/16) Photo 5. Mitigation planting area disturbed by car crash restored. (Photo taken 7/29/16) The Watershed Company December 2016 Photo 5. Buffer enhancement planting at the north end installed. (Photo taken 7/29/16) Photo 6. Critical area signs posted on split-rail fence. (Photo taken by client 12/1/16) Renton Canyon Terrace Wetland and Wetland Buffer Mitigation As-built Report M ONITORING T RANSECT PHOTOS All transect photos below were taken on November 7, 2016. Transect 1A - buffer: facing northwest Transect 1B – buffer: facing southeast Transect 2A - buffer: facing northwest Transect 2B - buffer: facing southeast The Watershed Company December 2016 Transect 3A - buffer: facing southwest Transect 3B - buffer: facing northeast Transect 4A - buffer: facing south Transect 4B – buffer: facing north Renton Canyon Terrace Wetland and Wetland Buffer Mitigation As-built Report Transect 5A – wetland: facing Transect 5B – wetland: facing southeast northwest The Watershed Company December 2016 M ONITORING P HOTOPOINT PHOTOS All transect photos below were taken on November 7, 2016. Photopoint 1 – buffer: panorama facing southwest Photopoint 2A – buffer: facing south Renton Canyon Terrace Wetland and Wetland Buffer Mitigation As-built Report Photopoint 2B – buffer: facing north Photopoint 3 – buffer: panorama facing southeast The Watershed Company December 2016 Photopoint 4 – buffer: panorama facing southwest Photopoint 5A – buffer: facing north Renton Canyon Terrace Wetland and Wetland Buffer Mitigation As-built Report Photopoint 5B – buffer: facing south Photopoint 6 – wetland: panorama facing southeast The Watershed Company December 2016 A PPENDIX C Plant Counts/Documentation Plant Installation Plant counts that differ from the approved As-Built plan are shown as revisions to the plan in Appendix A. As-built plant quantities are recorded in Table 3 below. All plants were supplied by Storm Lake Growers, Inc. in Monroe, Washington. Plants were installed by landscape contractor Pacific Green Landscapes. Table D-1. As-built plant counts for the entire project area. Common Name Botanical Name Qty per plan As-built Qty Douglas-fir Psuedotsuga menziesii 17 37 Cascara rhamnus purshiana 19 28 Scouler's willow Salix scouleriana 17 27 Western hemlock Tsuga heterophylla 13 34 Vine maple Acer circinatum 19 8 Serviceberry Amelanchier alnifolia 77 68 Redtwig dogwood Cornus sericea 52 102 Beaked hazelnut Corylus cornuta 62 62 Oceanspray Holodiscus discolor 60 117 Pacific wax myrtle Myrica californica 51 51 Sweet gale Myrica gale 0 5 Osoberry Oemleria cerasiformis 45 51 Baldhip rose Rosa gymnocarpa 92 98 Swamp rose Rosa pisocarpa 28 30 Thimbleberry Rubus parviflorus 52 32 Salmonberry Rubus spectabilis 54 54 Red elderberry Sambucus racemosa 68 57 Spirea Spiraea douglasii 37 43 Snowberry Symphoricarpos albus 57 102 Evergreen huckleberry Vaccinium ovatum 89 93 Highbush cranberry Vaccinium trilobum 0 5 Swordfern Polystichum munitum 0 127 Kinnikinnick Arctostaphylos uva- ursi 0 127 Salal Gaultheria shallon 0 20 Totals 909 1378 Renton Canyon Terrace Wetland and Wetland Buffer Mitigation As-built Report 2 Baseline Conditions Baseline plant counts were taken along each transect (see tables below). Belt-transects extend five feet from each side of the transect line, for a total width of ten feet. To be counted, a plant stem must be within the belt-transect; overhanging vegetation from adjacent areas does not count. Tree and shrub as-built plant counts will be compared to survival counts taken in late summer 2017. Table D-2. As-built plant counts using belt transect method in transects one through five (T1-T5). These counts represent all stems of plantings noted within five feet on each side of each of the transects. T1 Botanical name / common name As-built count Myrica cerifera / wax myrtle 7 Corylus cornuta / beaked hazelnut 2 Sambucus racemose / red elderberry 7 Holodiscus discolor / oceanspray 2 Amelanchier alnifolia / western serviceberry 5 T2 Botanical name / common name As-built count Oemleria cerasiformis / osoberry 6 Myrica cerifera / wax myrtle 9 Amelanchier alnifolia / western serviceberry 5 Sambucus racemose / red elderberry 2 Holodiscus discolor / oceanspray 2 Corylus cornuta / beaked hazelnut 3 T3 Botanical name / common name As-built count Salix sp. / willow 4 Holodiscus discolor / oceanspray 3 Corylus cornuta / beaked hazelnut 1 Cornus sericea / red osier dogwood 8 Gaultheria shallon / salal 9 Tsuga heterophylla / western hemlock 2 Symphoricarpos albus / snowberry 6 Rubus parviflorus / thimbleberry 2 Polystichum munitum / swordfern 9 Pseudotsuga menziesii / Douglas-fir 2 The Watershed Company December 2016 T4 Botanical name / common name As-built count Rubus spectabilis / salmonberry 6 Vaccinium ovatum / evergreen huckleberry 4 Acer circinatum / vine maple 3 Salix / willow 3 Pseudotsuga menziesii / Douglas-fir 5 Amelanchier alnifolia / western serviceberry 1 T5 Botanical name / common name As-built count Spiraea douglasii / hardhack 1 Rubus spectabilis / salmonberry 8 Myrica cerifera / wax myrtle 1 Polystichum munitum / swordfern 16 Gaultheria shallon / salal 12 Cornus sericea / red osier dogwood 8 Tsuga heterophylla / western hemlock 4 Pseudotsuga menziesii / Douglas-fir 2 Symphoricarpos albus / snowberry 5