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HomeMy WebLinkAboutYear-3 Monitoring Report_Complete December 6, 2021 Becky Hardi UW Medicine | Valley Medical Center Facilities Project Manager 400 S 43rd Street Renton, WA 98055 Via email: Becky_Hardi@Valleymed.org Re: Valley Medical Center Parking Garage Stream Buffer Mitigation, Year-3 Monitoring Report The Watershed Company Reference Number: 160113 Dear Becky: On October 22, 2022, Senior Ecologist, Ryan Kahlo, visited the Valley Medical Center stream buffer mitigation area to monitor the performance of the areas in accordance with the approved mitigation plan. This report documents the findings of the inspection and provides maintenance recommendations to help the site progress towards future goals and performance standards. Project History The mitigation plan was developed to allow for a parking garage expansion and associated grading activities within a stream buffer. The plan included buffer reductions with enhancement, buffer averaging with enhancement, and restoration of temporary buffer impacts, each of which is a separate, distinct area. The buffer enhancement area (Area A) measures 3,896 square feet; the temporary buffer impact area (Area B) measures 6,271 square feet; and the buffer addition with enhancement area (Area C) measures 1,948 square feet. Area A was installed in the fall-winter of 2017-2018, whereas Areas B and C were installed in late 2018. The as-built condition was documented in the as-built report, Valley Medical Center Parking Garage Stream Buffer Mitigation, As-built Report (The Watershed Company. February 25, 2019). The project is currently in Year-3 of a five-year monitoring program. Project Goals and Performance Standards The following goals and performance standards apply collectively to the planting areas. Mitigation Goals and Objectives Buffer Mitigation Year-3 Monitoring Report Becky Hardi, Valley Medical Center December 6, 2021 Page 2 1. Within the proposed restoration areas, establish dense native vegetation that is appropriate to the eco-region and site. 2. Where indicated on the plan, areas within the restoration area will remain substantially vegetated with a preponderance of native trees, shrubs, and groundcovers and will contain little invasive or noxious weed cover. Performance Standards 1. Survival: Achieve 100% survival of installed tree and shrub plantings by the end of Year 1. This standard can be met through plant establishment or through replanting as necessary to achieve the required numbers. Individual groundcover plantings cannot be feasibly counted. Therefore, groundcovers shall be monitored for areas of obvious mortality and appropriate replacement quantities recommended by the restoration professional to ensure satisfaction of the native cover standard (below). 2. Native Cover: a. Achieve 50% cover of native trees, shrubs, and groundcovers by Year 3. Native volunteer species (but not grasses) may count towards this cover standard. b. Achieve 80% cover of native trees, shrubs, and groundcovers by Year 5. Native volunteer species (but not grasses) may count towards this cover standard. Trees and shrubs must account for a minimum of 65% cover. c. Species diversity: Establish at least three native tree species, four native shrub species and one native groundcover species by Year 3 and maintain this diversity through Year 5. Native volunteer species (but not naturalized grasses) may count towards this standard. d. Invasive cover: Aerial cover for all non-native, invasive and noxious weeds within the buffer planting areas will not exceed 10% at any year during the monitoring period. Invasive plants are defined as those listed by the Washington State Noxious Weed Control Board as Class A, B, or C. Results The mitigation areas are continuing to progress as intended and have satisfied applicable performance standards for Year 3. Native vegetation is establishing, particularly in the canopy and shrub layers, and many trees are approaching 20 feet in height. The planting areas are on- schedule, or even slightly ahead of schedule, as related to native cover. On average, the site has achieved approximately 61 percent native woody cover, satisfying the Year 3 standard of 50 percent. The extensive drought across the region has contributed to stress for many of the shrub Buffer Mitigation Year-3 Monitoring Report Becky Hardi, Valley Medical Center December 6, 2021 Page 3 plantings (i.e., many salmonberry plantings dropped their leaves earlier than usual). However, actual mortality appears low, particularly with trees and shrubs. Sword fern plantings have struggled the most with the drought conditions, and it is unclear if the stressed sword ferns will rebound during 2022. Still, the site remains generally on-track to meet the Year-5 performance standard for cover (80%). Specific areas where establishment is falling short of the project goals are highlighted on the accompanying maintenance figure. These areas are generally isolated, but additional plantings should be installed in accordance with the recommendations below and the maintenance figure. Invasive species coverage is within the allowable limits of the performance standards. On average, coverage by invasive species is approximately three percent, including Himalayan blackberry, Canada thistle, and poison hemlock. Most occurrences of invasive species are isolated and/or encroaching from the outside the planting areas. Invasive species should be removed in accordance with the recommendations below and the maintenance figure. See Table 1 for a summary of native and invasive cover data by monitoring transect, including a comparison of Years 2 and 3. Table 1. Monitoring Transect Summary Transect Transect Length Native Cover Invasive Cover Year 2 Year 3 Year 2 Year 3 T-1 100 feet 49.5% 66.6% 0.0% 0.0% T-2 100 feet 64.3% 78.1% 7.3% 1.4% T-3 100 feet 32.9% 57.2% 1.5% 4.2% T-4 100 feet 54.4% 57.9% 0.0% 9.9% T-5 70 feet 34.6% 47.6% 0.4% 0.0% T-6 70 feet 38.9% 49.0% 10.2% 3.1% Average 50.8% 60.6% 3.6% 2.8% *Average is weighted by transect length Area A (Buffer Enhancement Area) Area A is performing very well, with native cover well ahead of where it typically is in the third year post-installation. Area A currently averages approximately 72 percent native cover. The black cottonwood trees have become well-established and are approaching 20 feet in height. Other prevalent species performing well at this planting area include bigleaf maple, salmonberry, snowberry, osoberry, black twinberry, Nootka rose, and sword fern. Invasive species coverage measured approximately three percent on average and is composed of Canada thistle and Himalayan blackberry. The blackberry is encroaching from the perimeter and should be cut back from the planting area as part of the routine site maintenance. Buffer Mitigation Year-3 Monitoring Report Becky Hardi, Valley Medical Center December 6, 2021 Page 4 Table 2. Area A Cover Measurements Transect Native Species Present Invasive Species Present Percent Cover Native Invasive T-1 Black cottonwood, salmonberry, Nootka rose, snowberry, twinberry None 66.6% 0.0% T-2 Bigleaf maple, black cottonwood, salmonberry, Nootka rose, snowberry, osoberry, sword fern Himalayan blackberry, Canada thistle 78.1% 1.4% Average 72.35% 0.7% Area B (Temporary Impact Area) Area B is on schedule for plant establishment and has satisfied the Year-3 standard for native cover. Native cover averages approximately 58 percent percent, with bigleaf maple, black cottonwood, twinberry, snowberry, Nootka rose, osoberry, and sword fern being the most prevalent species. A moderately sized black cottonwood tree installed as part of the mitigation has been partially uprooted and is laying over the split-rail fence. The tree is still alive and sprouting new vertical shoots. Unless this tree is determined to be a hazard, it should be allowed to persist, as it is providing substantial cover and habitat complexity to the site. Invasive species coverage measured approximately one percent on-average. Himalayan blackberry and trace amounts of Canada thistle were observed in the planting area. However, one particular area of concern is located at the western end of Area B, where a notable patch of poison hemlock has re-established. This patch was identified in Year 1 and subsequently treated. The presence was severely diminished in Year 2, but the aggressive species is re- establishing in the same location. Invasive species should be removed in accordance with the recommendations below and the maintenance figure. Additionally, since many of the plantings in the area where poison hemlock is establishing are groundcovers, additional trees and shrubs will help outcompete the species. Additional plants recommendations are provided below. Table 3. Area B Cover Measurements Transect Native Species Present Invasive Species Present Percent Cover Native Invasive T-3 Bigleaf maple, black cottonwood, beaked hazelnut, Nootka rose, snowberry, osoberry sword fern Himalayan blackberry 57.2% 4.2% T-4 Bigleaf maple, black cottonwood, black twinberry, snowberry, osoberry sword fern Himalayan blackbery 57.9 1.5% Average 57.6% 9.9%* *Includes 7% coverage of poison hemlock not captured in the transects Buffer Mitigation Year-3 Monitoring Report Becky Hardi, Valley Medical Center December 6, 2021 Page 5 Area C (Buffer Addition Area) Most of Area C is performing well; however, one area (approximately 150 square feet) near the southeast corner of the site has experienced substantial mortality and requires replacement plants to ensure future cover standards are met. Elsewhere, the plantings generally appear healthy and vigorous. Native cover is not as high as observed in Areas A and B, but it is still on- track to achieve future cover standards if the replacement plantings are installed per the recommendations below. Currently, native cover is approximately 48 percent, just below the Year-3 standard (50 percent). Areas not captured by the transects, within the narrow finger extending along the northwest side of Area C are performing slightly better than the main area. Prevalent native vegetation in Area C includes black cottonwood, bigleaf maple, Douglas-fir, tall Oregon grape, sword fern, salmonberry, and snowberry. Invasive species cover approximately two percent of the planting area. Invasive species observed in Area C include Himalayan blackberry and Canada thistle. English ivy is prevalent in the forested areas adjacent Area C and should continue to be cut back from the planting area. Table 4. Area C Cover Measurements Transect Native Species Present Invasive Species Present Percent Cover Native Invasive T-5 Black cottonwood, bigleaf maple, snowberry, Nootka rose, tall Oregon grape, Douglas-fir None 47.6% 0.0% T-6 Douglas-fir, Nootka rose, osoberry, snowberry, salmonberry, sword fern Himalayan blackberry 49.0% 3.1% Average 48.3% 1.6% Recommendations • Remove all invasive species by hand from the planting areas, making sure to grub out the roots. Particular attention should be paid to Himalayan blackberry, Canada thistle and English ivy. Cut back blackberry canes and ivy vines back at least 10 feet from planting areas. o For poison hemlock, spray foliage (leaves and stems) with aquatic glyphosate in the spring, followed by another application later in the summer for late sprouts. Spray plants before they flower for best results. Spraying may not prevent seed production in mature plants. Do not cut down the treated plants until they have died. Seeds germinate throughout the season, so repeat treatment is necessary to eliminate all plants. Application should be by a controlled method such as spot spray and only by a state-licensed applicator. Buffer Mitigation Year-3 Monitoring Report Becky Hardi, Valley Medical Center December 6, 2021 Page 6 Do not mow poison hemlock, due to the risk of inhaling toxins. Wear protective clothing, including gloves and long sleeves when working with or near poison hemlock. • In Area B, install additional plantings in the following quantities in the location indicated on the accompanying maintenance figure. o 2 black cottonwood (2 gallon) o 2 bigleaf maple (2 gallon) o 5 snowberry (1 gallon) o 5 Nootka rose (1 gallon) • In Area C, install the following replacement planting in the location indicated on the accompanying maintenance figure. o 2 bigleaf maple (2 gallon) o 6 snowberry (1 gallon) Please call if you have any questions or if we can provide you with any additional information. Sincerely, Ryan Kahlo, PWS Senior Ecologist Enclosures: Photopoints, Maintenance Figurs Photopoint 1 (Area A) Photopoint 2 (Area B) Photopoint 3 (Area B) Photopoint 4 (Area B) Photopoint 5 (Area C) Photopoint 6 (Area C) Photopoint 7 (Area C). Area in foreground to be replanted. STREAM OHWMTEMPORARY IMPACTS RESTORATION PLANTING AREA (6,271 SF)SILT FENCE (SHEET W7, DETAIL 1)SPLIT RAIL FENCE (SHEET W8, DETAIL 1)TREESACER MACROPHYLLUM / BIGLEAF MAPLEPSEUDOTSUGA MENZIESII / DOUGLAS-FIRPOPULUS BALSAMIFERA / COTTONWOODSHRUBSROSA GYMNOCARPA / BALDHIP ROSEMAHONIA AQUIFOLIUM / TALL OREGON GRAPEOEMLERIA CERASIFORMIS / OSO BERRYRUBUS SPECTABILIS / SALMONBERRYSYMPHORICARPOS ALBUS / SNOWBERRYGROUNDCOVERSPOLYSTICHUM MUNITUM / SWORD FERNQTY2413132626262626300SPACING9'-0" O.C.9'-0" O.C.9'-0" O.C.5'-0" O.C.5'-0" O.C.5'-0" O.C.5'-0" O.C.5'-0" O.C.2'-0" O.C..SIZE2 GAL.2 GAL.2 GAL.1 GAL.1 GAL.1 GAL.1 GAL.1 GAL.1 GAL.SBSTORAGEPROJECT MANAGER: DESIGNED: DRAFTED: CHECKED:SHEET SIZE:ORIGINAL PLAN IS 22" x 34".SCALE ACCORDINGLY.BY© Copyright- The Watershed CompanyDATE PRINTED BY FILENAME THEWATERSHEDCOMPANYS c i e n c e & D e s i g n750 Sixth Street SouthKirkland WA 98033p 425.822.5242www.watershedco.comJOB NUMBER:SHEET NUMBER:SUBMITTALS & REVISIONS DESCRIPTIONDATENO.RENTON VALLEY MEDICAL CENTER MITIGATION PLAN PREPARED FOR BECKY HARDI FACILITIES PROJECT MANAGER 400 S. 45RD STREET RENTON, WA 98055RKRK/KMBKMBRK160113OF 81 10-10-2016 REVIEW SET KMB 2 10-11-2016 CONSTRUCTION SET KMB 3 11-04-2016 ADDENDUM #2 10/25/2016KYLE BRAUN 160113_RENTON_VAL_MED_MITIGATION_PLAN.DWGTEMPORARY IMPACTS RESTORATION PLANB640'10'5'020'LEGENDTEMPORARY IMPACTS PLANTING SCHEDULESOIL PREPARATIONSTEP 1STEP 2STEP 3STEP 4MIN. 6"PLANTING AREA PREPARATIONSTEP 1REMOVE INVASIVE SPECIES. ADDRESSCOMPACTION TO A MINIMUM SIX (6) INCHDEPTH. COMPACTION LEVELS SHOULD BEAPPROPRIATE FOR ROOT GROWTH(75-85% PROCTOR DENSITY) OR ASOTHERWISE APPROVED BY RESTORATIONSPECIALIST. DRAINAGE RATE SHALL BEBETWEEN 1 - 5 INCHES PER HOUR OR ASOTHERWISE APPROVED BY THERESTORATION SPECIALIST. WORK WITHINROOT ZONES SHALL BE DONE BY HAND.STEP 2PLACE THREE (3) INCHES COMPOST ANDAMEND WITH DE-COMPACTED SOIL.STEP 3INSTALL WOOD CHIP MULCH 4" DEEP.STEP 4INSTALL PLANTS. (SEE PLANTING DETAIL.)4" WOODCHIPMULCH4"EXISTINGDEPTHVARIESSEQUENCE OF WORK - NOT TO SCALE3" STREAM OHWMSILT FENCE (SHEET W7, DETAIL 1)SPLIT RAIL FENCE (SHEET W8, DETAIL 1)SB S B DN UPSTAIR 7TREES / SPACING 9'-0" O.C.ACER MACROPHYLLUM / BIGLEAF MAPLEPSEUDOTSUGA MENZIESII / DOUGLAS-FIRPOPULUS BALSAMIFERA / COTTONWOODSHRUBS / SPACING 5'-0" O.C.ROSA GYMNOCARPA / BALDHIP ROSEMAHONIA AQUIFOLIUM / TALL OREGON GRAPEOEMLERIA CERASIFORMIS / OSO BERRYRUBUS SPECTABILIS / SALMONBERRYSYMPHORICARPOS ALBUS / SNOWBERRYGROUNDCOVERS / 2'-0" O.C.POLYSTICHUM MUNITUM / SWORD FERNQTY15991818181818150SPACING9'-0" O.C.9'-0" O.C.9'-0" O.C.5'-0" O.C.5'-0" O.C.5'-0" O.C.5'-0" O.C.5'-0" O.C.2'-0" O.C.SIZE2 GAL.2 GAL.2 GAL.1 GAL.1 GAL.1 GAL.1 GAL.1 GAL.1 GAL.PROJECT MANAGER: DESIGNED: DRAFTED: CHECKED:SHEET SIZE:ORIGINAL PLAN IS 22" x 34".SCALE ACCORDINGLY.BY© Copyright- The Watershed CompanyDATE PRINTED BY FILENAME THEWATERSHEDCOMPANYS c i e n c e & D e s i g n750 Sixth Street SouthKirkland WA 98033p 425.822.5242www.watershedco.comJOB NUMBER:SHEET NUMBER:SUBMITTALS & REVISIONS DESCRIPTIONDATENO.RENTON VALLEY MEDICAL CENTER MITIGATION PLAN PREPARED FOR BECKY HARDI FACILITIES PROJECT MANAGER 400 S. 45RD STREET RENTON, WA 98055RKRK/KMBKMBRK160113OF 81 10-10-2016 REVIEW SET KMB 2 10-11-2016 CONSTRUCTION SET KMB 3 11-04-2016 ADDENDUM #2 10/25/2016KYLE BRAUN 160113_RENTON_VAL_MED_MITIGATION_PLAN.DWGBUFFER AVERAGING PLANB520'5'2.5'010'LEGENDBUFFER AVERAGING PLANTING SCHEDULETEMPORARY IMPACTS TO BERESTORED PLANTING PLAN.SEE SHEET W6.SOIL PREPARATIONSTEP 1STEP 2STEP 3STEP 4MIN. 6"PLANTING AREA PREPARATIONSTEP 1REMOVE INVASIVE SPECIES. ADDRESSCOMPACTION TO A MINIMUM SIX (6) INCHDEPTH. COMPACTION LEVELS SHOULD BEAPPROPRIATE FOR ROOT GROWTH(75-85% PROCTOR DENSITY) OR ASOTHERWISE APPROVED BY RESTORATIONSPECIALIST. DRAINAGE RATE SHALL BEBETWEEN 1 - 5 INCHES PER HOUR OR ASOTHERWISE APPROVED BY THERESTORATION SPECIALIST. WORK WITHINROOT ZONES SHALL BE DONE BY HAND.STEP 2PLACE THREE (3) INCHES COMPOST ANDAMEND WITH DE-COMPACTED SOIL.STEP 3INSTALL WOOD CHIP MULCH 4" DEEP.STEP 4INSTALL PLANTS. (SEE PLANTING DETAIL.)4" WOODCHIPMULCH4"EXISTINGDEPTHVARIESSEQUENCE OF WORK - NOT TO SCALE3"