Loading...
HomeMy WebLinkAboutRS_VMAC_Year2_Compliance_Report_241021Wetland & Aquatic Sciences Wildlife Ecology Landscape Architecture 2111 N. Northgate Way, Ste 219 Seattle, WA 98133 206-525-8122 raedeke.com Associates, Inc. Raedeke TECHNICAL MEMORANDUM October 21, 2024 To: Mr. Sean Vanos From: Courtney Straight, BS, WPIT Raedeke Associates, Inc. Samantha Pohlman, BS Raedeke Associates, Inc. RE: VMAC Field Resurfacing Year 2 Performance Monitoring RAI Project No. 2021-136-003 This memorandum provides the results of our second-year monitoring of the Virginia Mason Athletic Center (VMAC) Field Resurfacing mitigation plan. The mitigation area meets the performance standards for aerial coverage, health (survival), and invasive species coverage required by the mitigation plans approved by the City of Renton. The VMAC Field Resurfacing project is located on a portion of an approximately 27-acre property (King County Tax Parcel Nos. 2924059015 and 2924059001) at 12 Seahawks Way in the City of Renton, King County, Washington. The property is located within a portion of Section 29, Township 24 North, Range 5 East, W.M. PROJECT BACKGROUND The buffer mitigation restoration area is located near the northwest corner of the VMAC training field, along the Lake Washington shoreline. The field resurfacing project required the removal of a substantial volume of soil from the fields by barge via Lake Washington. The project was regulated under the City of Renton Shoreline Master Program. The approved buffer zone mitigation plan (Raedeke Associates, Inc. 2021) provided restoration for 390 square feet of the dry upland buffer (Buffer Restoration Zone 1) and 190 square feet of the wet buffer with native vegetation (Buffer Restoration Zone 2). Mitigation plantings were installed on May 3, 2022, and compliance monitoring occurred on October 18, 2022. Mr. Sean Vanos October 21, 2024 Page 2 METHODS We completed our site inspection for the second-year performance monitoring on October 8, 2024. Sample plots were not established as the site is small enough to sample in its entirety. We tallied the number of individuals of each planted species and noted their general condition across the entire mitigation area (Table 1). Photographic reference points were established from each of the four cardinal directions. These photographic reference points will be used during each subsequent monitoring visit throughout the five-year long-term monitoring period to document plant community development. EVALUATION AND PERFORMANCE STANDARDS The evaluation criteria used in the monitoring process were defined in the Shoreline Mitigation Plan (Raedeke Associates, Inc. 2021) as approved by the City of Renton. The table below summarizes the performance standards for five years and summarizes the site conditions at the end of the second year. PERFORMANCE STANDARD YEAR 2 MONITORING RESULTS 1. 100% survival of all installed plant species for one year after planting. All plants that do not survive during the first year must be replaced with the same or similar species and specifications. Yes. Plant survival met 100% during the Year 1 monitoring and plantings are thriving. 2. Cover by shrub species will be: • at least 5% in Year 1 • at least 15% in Year 2 • at least 40% in Year 5 Yes. Average cover by shrub species is estimated at 25 to 30% in Year 2. The site is exceeding the required 15% Year 2 performance standard for shrub cover. 3. No more than 10% cover by non-native, invasive plant species at any time during the five-year monitoring period. Yes. The average cover by invasive species is estimated at approximately 2%. The site is meeting its Year 2 performance standard for less than 10% cover by invasive species. RESULTS The results of second-year monitoring are presented in Table 1 and Photo Plate 1(attached). The plants from the original installation efforts appeared healthy and robust. The average cover of installed shrubs was estimated at approximately 25-to30% across Mr. Sean Vanos October 21, 2024 Page 3 the mitigation site at the end of the second year of monitoring (see Photos 1 through 4; Photo Plate 1). All the plants appeared healthy and aerial coverage exceeded the 15% Year 2 performance standard. Invasive species coverage did not exceed 10% performance standard threshold and met the Year 2 performance standard. We observed very few invasive species within the mitigation site during our site visit except for a small area of trimmed reed canarygrass (Phalaris arundinacea) in the northwest corner of the mitigation area near the water’s edge and field bindweed (Convolvulus arvensis) growing on the slope in the northwest corner which covered approximately 2% of the site. CONCLUSION The project is currently meeting the second-year performance standards outlined in the mitigation plan. The plantings are well established and thriving within the mitigation area. Shrub cover in the mitigation area is approximately 25 to 30 percent aerial coverage and exceeds the 15% aerial coverage required in the performance standard. The planting area has only approximately 2% coverage by invasive species and is meeting the second-year performance standard. A follow-up site inspection of the mitigation area to document third year maintenance monitoring should be conducted in Spring 2024. MAINTENANCE ACTIONS The following maintenance actions should be completed in 2024-2025: • Continue to remove invasive species – To avoid accidental mortality to installed plants, do not use mechanical brush cutters or line trimmers within the site. Invasive species should be carefully pulled back from installed plants, dug out by the roots, and disposed of off-site. Originally installed plants have successfully been established within the site and have increased in size, contributing to the native cover required for the mitigation site. Any maintenance conducted should prioritize retention of the installed plants over the speed of cutting back invasives. We recommend that invasive reed canarygrass and field bindweed continue to be regularly removed from the mitigation area. • If deer continue to graze on the vegetation, it may be useful to install deer fencing to help the established plants, but it is not required. LIMITATIONS We have prepared this memo for the exclusive use of the Seattle Seahawks and their consultants. No other person or agency may rely upon the information, analysis, or conclusions contained herein without permission from the Seattle Seahawks. Mr. Sean Vanos October 21, 2024 Page 4 We warrant that the work performed conforms to standards generally accepted in our field and has been 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. If you have any questions or comments, please contact Courtney Straight and Samantha Pohlman at (206) 525-8122 or cstraight@raedeke.com and spohlman@raedeke.com. LITERATURE CITED Renton, City of. 2021. Renton Municipal Code. Title IV Chapter 3 Environmental Regulations and Overlay Districts. Current through Ordinance 6029, passed October 18, 2021. Available at: https://www.codepublishing.com/WA/Renton/html/Renton04/Renton0403/Renton 0403.html. Raedeke Associates, Inc. 2021. Shoreline Mitigation Plan – VMAC Field Resurfacing. December 1, 2021, plan set prepared for Seattle Seahawks, Renton, Washington. Raedeke Associates, Inc. 2022. VMAC Field Resurfacing Year 1 Compliance Monitoring prepared for Seattle Seahawks, Renton, Washington. # Required Per Plan Year 1 Year 2 QTY. (2021) QTY. (1/2024) QTY. (10/2024) Scientific Name Common Name Athyrium cyclosorum Western lady fern 15 0 3 Carex lenticularis Lakeshore sedge 10 20 20 Mahonia nervosa Cascade Oregon-grape 5 7 7 Gaultheria shallon Salal 5 5 3 Rosa pisocarpa Clustered rose 7 9 9 Rosa nutkana Nootka rose 6 7 11 Symphoricarpus albus Common snowberry 3 6 9 Cornus alba Red osier dogwood 0 1 2 Totals 51 55 64 5%15-20%25-30% <10%3%2%Percent Invasive Cover Average Installed Shrub Cover SAPLINGS and SHRUBS Table 1. VMAC Mitigation - Number of plantings recorded during Year 2 monitoring (October 8, 2024). \\192.168.111.7\Projects\2021\2021-136 VMAC Field Resurfacing\Year 2 Monitoring\Table 1. VMAC Mitigation - Year 2 Monitoring DATA \\192.168.111.7\Projects\2021\2021-136 VMAC Field Resurfacing\Year 2 Monitoring\Photoplate 1.doc Photo-plate 1 Photo 1 Northwest corner (downslope) of mitigation area, looking South. Photo 2 Southeast side (upslope) of the mitigation area, looking West. Photo 3 Southwest corner (downslope) of mitigation area, looking Southeast. Photo 4 Southwest (water) side, downslope of the mitigation area, looking North.