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Home My WebLink AboutC_Mitigation_Email_May_Creek_Trestle_Project_191029_v11 Clark Close From:Blair, Misty (ECY) <mbla461@ECY.WA.GOV> Sent:Tuesday, October 29, 2019 2:31 PM To:Erickson, Chris Cc:Clark Close; Kevin O'Brien (Kevin.O'Brien@otak.com); Bob Doherty (Bob.Doherty@otak.com); Miller, Lindsey Subject:RE: Proposed Mitigation - Renton Permit LUA18-000421 - May Creek Trestle Project Chris, Thank you for provided this Conceptual Mitigation Plan. This is consistent with what we discussed back in August and would be an acceptable approach to meet Condition #2 of your Shoreline Conditional Use Permit # 2018-NW-4492. Misty Blair | Shoreline Management Policy Lead WA Department of Ecology | P 425-649-4309| misty.blair@ecy.wa.gov From: Erickson, Chris <Chris.Erickson@kingcounty.gov> Sent: Tuesday, October 29, 2019 12:58 PM To: Blair, Misty (ECY) <mbla461@ECY.WA.GOV> Cc: Clark Close <CClose@Rentonwa.gov>; Kevin O'Brien (Kevin.O'Brien@otak.com) <Kevin.O'Brien@otak.com>; Bob Doherty (Bob.Doherty@otak.com) <Bob.Doherty@otak.com>; Miller, Lindsey <Lindsey.Miller@kingcounty.gov> Subject: Proposed Mitigation - Renton Permit LUA18-000421 - May Creek Trestle Project THIS EMAIL ORIGINATED FROM OUTSIDE THE WASHINGTON STATE EMAIL SYSTEM - Take caution not to open attachments or links unless you know the sender AND were expecting the attachment or the link Hi Misty, In follow-up to our late August phone conference in which a proposed mitigation plan was requested by the State DOE in order to authorize work under City of Renton Permit LUA18-000421, please see attached. If this proposal is acceptable by you we will amend our Consultant contract to get them working on the detailed mitigation drawing plan for approval and incorporation into the permit documents. We look forward to your review and response. Thank you. Chris Erickson l Project Manager l King County DNRP Parks Division l CIP Unit 201 South Jackson Street, #700, Seattle, WA 98104 PH: 206-477-4564 l CL: 425-931-6319 l FX: 206-588-8011 1 Otak, Inc. October 25, 2019 Technical Memorandum To: Misty Blair, DOE, Senior Shoreline Planner From: Copies: Kevin O’Brien, Senior Ecologist Otak, Inc. on behalf of King County Parks Chris Erickson, King County Parks, Capital Project Manager Clark Close, City of Renton, Senior Planner Bob Doherty, SE, Otak, Inc.; File Date Submitted: October 25, 2019 Subject: Conceptual Mitigation for May Creek Trestle Bridge Repair (Department of Ecology Shoreline Conditional Use (Permit #2018-NW-4492) The following represents proposed conceptual mitigation, requested by Washington State Department of Ecology (DOE) in an approval letter for a Shoreline Conditional Use Permit (CUP). King County is proposing repair and rehabilitation of an existing timber trestle bridge crossing May Creek in the City of Renton. The project intends to repair and retrofit the May Creek trestle bridge. The trestle is currently used as recreational pedestrian bridge and is planned to become part of the multi-use Eastside Rail Corridor (ERC) regional trail in Renton. The trestle is deteriorated and has defects and requires repairs to provide continuous use of the trail system. A previous bridge inspection revealed defects and deterioration in timber members, including internal decay in timber piles, back walls and wing walls. Repairs are required to utilize the bridge for the ERC Trail and to accommodate the desired lifespan of the structure. In addition to repairs and rehabilitation of the existing components of the trestle bridge, the existing timber railroad ties, steel railroad tracks and fencing will be removed, and new decking and railing will be installed. The portion of May Creek that the project trestle bridge crosses is a Shoreline of the State, and a shoreline permit was required for the proposed work. The City of Renton issued a Shoreline 11241 Willows Drive Suite 200 Redmond, WA 98052 Phone (425) 822-4446 Fax (425) 827-9577 2 Otak, Inc. October 25, 2019 Conditional Use Permit on December 19, 2018 and DOE issued an approval letter on January 29, 2019 with stipulated conditions. Previous communications with DOE provided responses and answers to DOE questions and comments (Otak Technical Memo dated July 9, 2019). Subsequent communications with Misty Blair at DOE on August 26, 2019 established that DOE wished for the project to provide mitigation for potential shading effects of the trestle bridge. Shading effects have been associated with lower overwater structures that are inches or a few feet above the water surface. Such structures often impose a clear demarcation between ambient light and darkness under the overwater structure that may disrupt salmonid juvenile migration and movement behavior and are typically found in marine or lake habitats. Mitigation sequencing for the project to include avoidance and minimization was provided in the July 9, 2019 Otak memo and previously submitted permit applications and regulatory compliance documentation. Proposed mitigation concepts for the May Creek trestle bridge repair project are as follows: 1. In accordance with City of Renton (COR) Critical Areas Ordinance 4-3-050L 1.c., the proposed conceptual mitigation is based on interpretation of best available science as described below in the mitigation rationale. 2. In accordance with City of Renton (COR) Critical Areas Ordinance 4-3-050L 1.d.i. and 1.g.i(a), proposed mitigation will take place on-site as a preferred location. 3. In accordance with City of Renton (COR) Critical Areas Ordinance 4-3-050L 1.g.ii(d), proposed mitigation will be suitable for site and water body conditions that meet all other provisions for a mitigation plan. 4. Proposed mitigation consists of installation of native riparian plantings upstream and downstream of the trestle bridge sufficient to shade May Creek at these locations. • Rationale: Shading provided by additional riparian plantings will obviate a line of light/shade demarcation in the water between the area under the bridge and the surrounding stream habitat. Ambient light conditions during the day will consist of either uniformly shaded stream habitat or “dappled” conditions of a mix of shade and sunshine. • Rationale: Additional riparian plantings provide allochthonous input of material into the local stream food web: • Terrestrial invertebrates to augment the prey base for juvenile salmonids • Leaf litter to augment the food resource base for aquatic invertebrate belonging to certain functional feeding groups—e.g. shredders, collector/gatherers. • Rationale: Additional riparian plantings provide overall localized shading that may reduce water temperatures in the May Creek reach vicinities—providing an ecological lift to in-migrating salmonids and rearing juveniles relying upon appropriate in-stream water temperatures for their life history stages. • Rationale: Additional riparian plantings may serve to further discourage social trails and access to the area in the vicinity of the trestle bridge—reducing or removing 3 Otak, Inc. October 25, 2019 human-based disturbances to the stream habitat in general and local salmonids in particular. 5. Monitoring may be conducted as part of the conceptual mitigation approach, per City of Renton (COR) Critical Areas Ordinance 4-3-050L 3. and would consist of evaluating the survivorship and density of the native plantings and assessing cover by non-native invasive plant species. Performance standards for riparian vegetation will conform to standards as outlined in Appendix A – “King County Parks Mitigation Planting Standards Document”. Please feel free to contact me if you have any questions or concerns. Sincerely, Kevin O’Brien, Ph.D. Otak, Inc. Senior Ecologist and Wildlife Biologist (425)739-7975 APPENDIX A KING COUNTY PARKS MITIGATION PLANTING STANDARDS DOCUMENT PERFORMANCE STANDARDS SURVIVAL YEAR 1 – SURVIVAL OF PLANTED VEGETATION IN THE MITIGATION AREA WILL BE 100 PERCENT. THE CONTRACTOR IS RESPONSIBLE FOR ENSURING THIS PERFORMANCE STANDARD IS MET. YEAR 2 – SURVIVAL OF PLANTED VEGETATION IN THE MITIGATION AREA WILL BE 90 PERCENT. KING COUNTY IS RESPONSIBLE FOR ENSURING THIS PERFORMANCE STANDARD IS MET. YEAR 3 – SURVIVAL OF PLANTED VEGETATION IN THE MITIGATION AREA WILL BE 85 PERCENT. KING COUNTY IS RESPONSIBLE FOR ENSURING THIS PERFORMANCE STANDARD IS MET. COVER YEAR 2 – NATIVE WOODY SPECIES SHALL ACHIEVE A MINIMUM OF 25 PERCENT AREAL COVER IN THE MITIGATION AREA. KING COUNTY IS RESPONSIBLE FOR ENSURING THIS PERFORMANCE STANDARD IS MET. YEAR 3 – NATIVE WOODY SPECIES SHALL ACHIEVE A MINIMUM OF 35 PERCENT AREAL COVER IN THE MITIGATION AREA. KING COUNTY IS RESPONSIBLE FOR ENSURING THIS PERFORMANCE STANDARD IS MET. YEAR 4 – NATIVE WOODY SPECIES SHALL ACHIEVE A MINIMUM OF 50 PERCENT AREAL COVER IN THE MITIGATION AREA. KING COUNTY IS RESPONSIBLE FOR ENSURING THIS PERFORMANCE STANDARD IS MET. YEAR 5 – NATIVE WOODY SPECIES SHALL ACHIEVE A MINIMUM OF 60 PERCENT AREAL COVER IN THE MITIGATION AREA. KING COUNTY IS RESPONSIBLE FOR ENSURING THIS PERFORMANCE STANDARD IS MET. INVASIVE VEGETATION NON-NATIVE, INVASIVE SPECIES WILL NOT EXCEED 10 PERCENT. NON-NATIVE, INVASIVE SPECIES MAY INCLUDE, BUT ARE NOT LIMITED TO: HIMALAYAN BLACKBERRY (RUBUS ARMENIACUS), CUTLEAF BLACKBERRY (RUBUS LACINATUS), SCOTCH BROOM (CYTISUS SCOPARIUS), CANADA THISTLE (CIRSIUM ARVENSE), BULL THISTLE (CIRSIUM VULGARE), REED CANARYGRASS (PHALARIS ARUNDINACEA), JAPANESE KNOTWEED (POLYGONUM CUSPIDATUM). THE CONTRACTOR IS RESPONSIBLE FOR ENSURING THIS PERFORMANCE STANDARD IS MET DURING YEAR 1 AND KING COUNTY IS RESPONSIBLE FOR ENSURING THIS PERFORMANCE STANDARD IS MET FOR YEARS 2-5. PERFORMANCE STANDARD: KING COUNTY HAS ZERO TOLERANCE FOR REGULATED CLASS A, B, AND C NOXIOUS WEEDS AS DEFINED BY THE KING COUNTY NOXIOUS WEED CONTROL BOARD. THE CONTRACTOR IS RESPONSIBLE FOR ENSURING THIS PERFORMANCE STANDARD IS MET DURING YEAR 1 AND KING COUNTY IS RESPONSIBLE FOR ENSURING THIS PERFORMANCE STANDARD IS MET FOR YEARS 2-5. MONITORING AND REPORTING THE MITIGATION AREA WILL BE MONITORED DURING AND AFTER CONSTRUCTION. DURING CONSTRUCTION, THE SITE WILL BE MONITORED TO ENSURE THAT BEST MANAGEMENT PRACTICES (BMPS) ARE OBSERVED AND THE SITE IS CONSTRUCTED AS DESIGNED. AFTER CONSTRUCTION, AN AS-BUILT MITIGATION REPORT WILL BE PREPARED. SUBSEQUENT MONITORING WOULD OCCUR FOR 4 YEARS (YEARS 2-5) ANNUALLY TO ENSURE THAT THE GOALS AND OBJECTIVES OF THE MITIGATION ARE BEING MET. SITE INSPECTIONS SHALL OCCUR AT LEAST QUARTERLY AND AN ANNUAL MONITORING REPORT WILL BE SUBMITTED TO [THE PERMITTING AGENCIES WITH JURISDICTION] BY FEBRUARY 15 OF THE FOLLOWING YEAR. MAINTENANCE KING COUNTY WILL MAKE PROVISIONS FOR WATERING AS NEEDED FOR THE REMAINDER OF THE ESTABLISHMENT PERIOD AFTER THE FIRST YEAR. REMOVAL OF TRASH OR OTHER ANTHROPOGENIC DEBRIS WILL BE REMOVED DURING MAINTENANCE ACTIVITIES. QUALITATIVE MONITORING WILL BE CONDUCTED YEARLY TO ASSESS THE STATUS OF THE MITIGATION AREA FOR HUMAN DISTURBANCE, INCLUDING BUT NOT LIMITED TO FILLING, TRASH, AND VANDALISM. NON-NATIVE, INVASIVE SPECIES WILL BE REMOVED BY MANUAL METHODS. MANUAL REMOVAL OF INVASIVE SPECIES CAN BE DONE BY CLEARING AND GRUBBING PLANTS AND THEIR ENTIRE ROOT SYSTEMS. USE OF HERBICIDE IS ALLOWED UNDER SPECIAL CIRCUMSTANCES AND WILL ONLY BE USED WHEN MANUAL METHODS PROVE UNSUCCESSFUL. ONLY WASHINGTON STATE DEPARTMENT OF AGRICULTURE LICENSED PESTICIDE APPLICATORS WITH AN AQUATIC ENDORSEMENT, OR PERSONS WORKING UNDER THE DIRECT SUPERVISION OF SUCH AN APPLICATOR, CAN USE AQUATIC PESTICIDE FORMULATIONS. DISPOSE OF INVASIVE SPECIES OFF SITE IMMEDIATELY. AT NO TIME DURING THE MONITORING PERIOD WILL INVASIVE SPECIES EXCEED 10 PERCENT AERIAL COVERAGE. CONTIGENCY MEASURES HIGH MORTALITY COULD RESULT FROM IMPROPER INSTALLATION, DISEASED OR INFESTED PLANTS, INADEQUATE WATERING, OR EXTREME WEATHER. IF MORE THAN 25 PERCENT OF NEW PLANTINGS DIE IN A SINGLE YEAR, THE CAUSE OF THE HIGH LOSSES WILL BE INVESTIGATED AND CORRECTED BEFORE DEAD PLANTS ARE REPLACED. DEAD PLANT MATERIAL WILL ONLY BE REMOVED AFTER THAT YEAR’S SCHEDULED MONITORING. HOWEVER, PLANT MORTALITY CAN ALSO OCCUR FROM PLANT COMPETITION WITH SURROUNDING NATIVE PLANTS. THEREFORE, IN ANY YEAR, IF THE PERCENT SURVIVAL PERFORMANCE STANDARD IS NOT MET, BUT THE PERCENT COVER OF NATIVE PLANTS PERFORMANCE STANDARD IS MET, THEN ADDITIONAL PLANTS MAY NOT HAVE TO BE INSTALLED. HOWEVER, IN ANY GIVEN YEAR IF BOTH THE PERCENT SURVIVAL AND PERCENT COVER OF NATIVE PLANTS PERFORMANCE STANDARDS ARE NOT MET, THEN THE CONTINGENCY MEASURE WOULD INCLUDE INSTALLING ADDITIONAL PLANTS TO BRING THE PLANTING SCHEDULE BACK INTO ORIGINAL SPECIFICATIONS. IF THE PERCENT COVER OF SUCCESS CRITERIA IS NOT MET, THE CAUSE WILL BE INVESTIGATED AND CORRECTED. CORRECTION MEASURES MAY INCLUDE INCREASED WATERING, SOIL AMENDMENTS, OR ADDITIONAL PLANTINGS.