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WetlandReport.pdfDelineation! Mitigation i Restoration Habitat Creation i Permit Assistance 9505 19th Avenue S.E. Suite 106 Everett, Washington 98208 (425) 337-3174 Fax (425) 337-3045 Wetland Mitigation Plan for Michel Construction - 74th Place West Lots 15911, 15915 and 15917 Wetland Resources, Inc. Project #03287 Prepared By: Wetland Resources, Inc. 9505 19th Ave. SE Suite 106 Everett, WA 98208 (425) 337-3174 For: Michel Construction Attn. Rob Michel 7907 212t' St. SW #212 Edmonds, WA 98026 October 8, 2003 Revision 1: December 2, 2003 APPROVED By PLANNING JAN 2 2 2004 STREET TABLE OF CONTENTS Site Description Project Description Wetland Functions and Values Assessment Mitigation Procedure Grass Seeding Project and Planting Notes Performance Bond Project Monitoring Program Maintenance Performance Goals Contingency Plan Use of this Wetland Mitigation Plan References Wetland Mitigation Map 1 1 2 4 5 5 6 7 8 8 8 9 10 1/1 SITE DESCRIPTION Wetland Resources, Inc. conducted a wetland delineation on January 11, 2002 to locate jurisdictional wetlands on three half -acre lots located at 15911, 15915, and 15917, 74h Place West in the city of Edmonds, Washington. The site is located as part of Section 5, Township 27N, Range 4E, W.M. All three lots were investigated for the presence of critical areas. Critical areas are present only on lot 15917 and this is the only property that will be discussed hereafter. This site is located east of the right of way of an unopened portion of 74�' Place West. This site is located on a hill that slopes down from the east to the west. It appears that this hill was terraced at some time in the past. Topography of the site slopes up from 74h Place West in the west. A Category 3 wetland is located in the western portion of this property. This wetland drains to a Category 2 stream that flows along the southern property boundary. in the city of Edmonds, Category 3 wetlands and Category 2 streams are given 25 foot protective buffers. Typical vegetation on-site is represented by a canopy of big leaf maple (Acer macrophyllum, FacU) and red alder (Alnus rubra, Fac), with an understory of satmonberry (Rebus spectabilis, Facf), Himalayan blackberry (Rubus discolor, FacU), and dewberry (Rubus ursinus, FacU). Vegetation in the wetland is represented by Himalayan blackberry (R. discolor, FacU), small fruit bullrush (Scirpus microcarpus, Obl), field horsetail (Equisetum arvense, Fac), and lady fern (Athyrium filix-femina, Fac). PROJECT DESCRIPTION The applicant is proposing to construct one single-family residence on this property. Due to site topography and the location of the on-site wetland, complying with ECDC 20.156 would deny reasonable use of the property, as found by the Hearing Examiner (Case No. V-2002-222, 223, 224, Ft 225). To achieve a reasonable use of this property, the applicant is proposing to construct a single- family residence white minimizing impacts to the wetland and on-site stream buffer to the greatest extent possible. As a result of site preparation and placement of the house, 2,445 square feet of the on-site wetland is proposed to be filled. In addition, the 25 -foot buffer from the remaining non -impacted portion of the on-site Category 3 wetland is proposed to be graded to provide appropriate side slopes . from the development. This will temporarily impact 1,195 square feet of buffer area which will be restored upon completion of grading activities. To accommodate the driveway and required setbacks from the house, a total of 585 square feet of buffer is proposed to be impacted. This buffer is currently dominated by Himalayan blackberry and Japanese knotweed. To replace lost functions and values provided by the filled wetland and to comply with the no net loss of size requirement in the City of Edmonds code, mitigation is offered in the following manner. The on-site portion of the Category 2 stream buffer (560 square feet) is proposed to be enhanced through control of invasive species and planting of native species. To prevent grading or other impacts to the stream buffer, silt fence shalt be placed around outer perimeter of this buffer prior to any site disturbance. To ensure that 1 any inadvertent impacts are restored, the proposed buffer enhancement will take place after completion of grading activities and concurrent with buffer restoration (discussed below). Upon completion of grading within the 25 -foot buffer from the existing wetland, this 1,195 square foot area will be restored through planting of native trees and shrubs. To comply with the no net loss of size requirement in the City of Edmonds code, the applicant is proposing to replace the 2,445 square feet of impacted wetland with additional buffer at a 2.5 to 1 (additional buffer to wetland impact) ratio. This will amount to 6,113 square feet of additional buffer. As mitigation for the 585 square feet of buffer impacts, the applicant is proposing to designate 585 square feet of additional buffer. This will amount to a total of 6,698 square feet of additional area as buffer. The area to be designated as additional buffer is represented by a canopy of big leaf maple with sword fern in the understory. This is proposed to be enhanced by planting conifers throughout this area on 15 -foot centers. To ensure that stream flows are not impacted by this project, a French drain will be placed in the yard of the proposed house. This drain will outflow into the stream buffer via a level spreader trench. WETLAND FUNCTIONS AND VALUES ASSESSMENT Methodology The methodology for this functions and values assessment is based on professional opinion developed through past field analyses and interpretation. This assessment pertains specifically to the on-site wetland system, but is typical for assessments of similar systems common to western Washington. Functions and Values Components Wetlands in western Washington perform a variety of ecosystem functions. Included among the most important functions provided by wetlands are stormwater control, water quality improvement, fish and wildlife habitat, aesthetic value, recreational opportunities, and education. The most commonly assessed functions are Stormwater Storage/Ftoodflow Attenuation, Water Quality, and Wildlife Habitat. Assessments of these functions for the project site are provided below. Analysis Stormwater Storage/Ftoodflow Attenuation Due to the location of this wetland within the landscape, this wetland has the potential to make beneficial contributions to the functions of stormwater storage and floodflow attenuation. The size of the wetland allows it to collect and store water as it drains from the surrounding hillside and slowly release it to the associated stream. Water Quality This wetland has the ability to make moderate contributions to the function of water quality. As water passes through this wetland, the size and presence of emergent vegetation slows the water, allowing suspended sediments to settle. Along with this, the emergent vegetation takes up and traps nutrients, thus preventing downstream eutrophication. Wildlife Habitat Given the small size, lack of vegetative structure, limited species diversity, and proximity to surrounding development, this wetland only has the potential to make minimal contributions to wildlife habitat. The most important benefit is food and cover to birds, amphibians, and small mammals. Proposed Impacts to Functions and Values In order to accommodate a single-family residence and associated infrastructure on this site, the applicant is proposing to fill 2,445 square feet of the on-site Category 3 wetland and to impact 585 square feet of associated buffer. Post Mitigation Functions and Values As mitigation for impacts to the on-site wetland and buffer, the applicant is proposing to designate and enhance a total of 6,698 square feet of area as additional buffer. This 6,698 square feet of additional buffer along with the entire on-site portion of the stream buffer (560 square feet) is proposed to be enhanced through control of invasive species and planting of native species. In addition, the 1,195 square feet of wetland buffer to be graded will be restored using native shrubs. To ensure that stream flows are not impacted by this project, a French drain wilt be placed in the yard of the proposed house. This drain will outflow in to the stream buffer via a level spreader. Although impacts are proposed to occur in the majority of the on-site wetland and portions of the buffer, the level of functions and values provided by this system will remain approximately equivalent or will improve. Preservation and enhancement of the on-site stream buffer, restoration of the 1,195 square feet of on-site wettand buffer to a better than existing condition, and designation and enhancement of 6,698 square feet of additional buffer area is proposed. This mitigation will help to increase species diversity, improve vegetative structure and control invasive species which are currently dominant in the stream buffer. Other benefits will be an increase in wildlife habitat, including a movement corridor along the southern border of the property. Planting conifer trees throughout the area designated as additional buffer will facilitate the transition from a deciduous to. a mixed and eventually a coniferous canopy, and will result in long term improvements to functions and values of the site. 3 Stormwater storage, floodflow attenuation, and water quality values witl be maintained if not improved by collecting stormwater runoff from the site, treating it in a detention system and releasing it downstream. Stream flows will be maintained by collecting water from the yard in a French drain and releasing it into the stream buffer via a level spreader. Given the relatively low initial quality of this wettand and the proposed mitigation measures, this project should result in negligible impacts, or even slight improvements to analyzed functions and values. MITIGATION PROCEDURE As partial mitigation for on-site wetland and buffer impacts, the applicant is proposing to designate 6,698 square feet of area as additional buffer. This area will be enhanced through control of invasive species and planting of native conifer trees. To accommodate existing native vegetation, these trees will be planted throughout this area on 15 -foot centers. The 1,195 square feet of on-site wetland buffer will be graded as a part of site preparation. This grading will remove all invasive species. After grading the level spreader should be installed. Upon completion of site work, the buffer restoration area should be seeded with the grass seed mixture recommended in this plan, and planted with the species listed below. No grading will take place in the stream buffer. To ensure this, the edge of this buffer will be marked with silt fence before commencement of any grading activities. Should any inadvertent grading occur, the graded areas should be restored in the same manner as the additional buffer area. In areas not graded, all invasive species (mainly Himalayan blackberry and Japanese knotweed) should be removed by the root. Of the 560 square feet of on-site stream buffer, 215 square feet of this is wetland. This area will remain wetland. Following control of invasive species, the species recommended below should be installed in the appropriate locations. rd Additional Buffer 6,698 square feet) Common Name Latin Name Size Spacing Quantity 1. Douglas fir Pseudotsuga menziesii 1 gallon 15' 10 2. Western hemlock Tsuga heterophylla 1 gallon 15' 10 3. Western red cedar Thuja plicata 1 gallon 15' 10 Stream Buffer (upland 345 square feet) Common Name Latin Name Size Spacing Quantity 1. Vine maple Acer circinatum 1 gallon 9' 2 2. Sitka mountain ash Sorbus sitchensis 1 gallon 9' 2 3. Snowberry Symphoricarpos albus 1 gallon 4.5' 7 4. Oregon grape Berberis nervosa 1 gallon 4.5' 7 rd Stream Buffer (wetland 215 square feet) (1,195 square Common Name Latin Name Size Spacing Quantity 1. Red -osier dogwood Cornus sericea 1 gallon 9' 1 2. Black twinberry Lonicera involucrata 1 gallon 9' 1 3. *Slough sedge Carex obnupta plugs 1.5' 20 4. *Small -flowered bulrushScirpus microcarpos plugs 1.5' 20 *Slough sedge and small -flowered bulrush should be planted in clumps, each covering 20 percent of the wetland area. GRASS SEEDING All disturbed soil within critical areas and buffers shall be seeded to the recommended, certified grass seed mixture below. Fertilizer shall only be used when absolutely necessary due to potential runoff into sensitive stream and wetland systems. If deemed absolutely necessary by the consulting biologist and/or the County Biologist, a fertilizer such as 16-16-16 shall be applied at 100 pounds per acre. Buffer Grass Seed Mixture Common Name Wetland Buffer Restoration (1,195 square feet) Agrostis tenuis Common Name Latin Name Size Spacing Quantity 1. Vine maple Acer circinatum 1 gallon 9' S 2. Sitka mountain ash Sorbus sitchensis 1 gallon 9' 7 3. Snowberry Symphoricarpos albus 1 gallon 4.5' 22 4. Oregon grape Berberis nervosa 1 gallon 4.5' 22 GRASS SEEDING All disturbed soil within critical areas and buffers shall be seeded to the recommended, certified grass seed mixture below. Fertilizer shall only be used when absolutely necessary due to potential runoff into sensitive stream and wetland systems. If deemed absolutely necessary by the consulting biologist and/or the County Biologist, a fertilizer such as 16-16-16 shall be applied at 100 pounds per acre. Buffer Grass Seed Mixture Common Name Latin Name lbs./1 000 s.f. Colonial bentgrass Agrostis tenuis 0.6 Annual ryegrass Lolium multiflorum 0.3 White clover Trifolium repens 0.2 Wetland Grass Seed Mixture Common Name Latin Name lbs./1,000 s.f. Annual ryegrass Lolium multiflorum 0.4 Redtop bentgrass Agrostis alba 0.4 Meadow foxtail Alopecurus pratensis 0.6 American sloughgrass Beckmannia syzigachne 0.6 PROJECT AND PLANTING NOTES A meeting wit[ take place between the consulting biologist and the contracted landscaper prior to commencement of enhancement activities. This will provide an opportunity to clarify any questions that may arise and ensure success of the enhancement project in a timely manner. Siltation fencing shall be placed as shown on the TESC design and be inspected prior to any mitigation site disturbance. These measures wit[ help to ensure that the on-site construction activities wilt have 5 the minimum impact to on-site critical areas necessary to achieve completion of the project. Mulch: Wood chips, or other appropriate material, shall be used for mulching in the planting area. Any existing vegetation is to be removed from a two -foot diameter area at each planting site. Wood chips are to be placed in this two -foot diameter area at a depth of three to four inches. A four -inch diameter ring around the base of each plant shalt be kept free of mulch. Planting holes should be dug to twice the required size and partially backfilted with a high quality compost. Plant in the early spring or late fall. Order plants from a reputable nursery. Care and handling of plant materials is extremely important to the overall success of the project. All plant materials recommended in this plan should be available from local and regional sources, depending on seasonal demand. Some limited species substitution may be allowed, only with the agreement of the consulting wetland professional. Plants shalt be arranged with the appropriate numbers, sizes, species, and distribution to achieve the desired vegetation coverage. The actual placement of individual plants shalt mimic natural, asymmetric vegetation patterns found on similar undisturbed sites in the area. Lath stakes or similar approved marking system should be placed next to each planted tree and shrub to assist in locating the plants during monitoring and while removing the competing non-native vegetation. This will be done for all installed plants. PERFORMANCE BOND A performance bond shall be provided to the City of Edmonds for the period of three years from the completion of the project, in the amount of 120% of the estimated cost for plant material and labor. Annual monitoring reports and seasonal maintenance will be required to assure the success of this enhancement plan. The City of Edmonds shall release this bond at the end of the three years, upon successful determination for all portions of this mitigation project. The following is an estimate of plant materials and tabor only. This does not represent a bid to install: QUANTITY OF ONE GALLON PLANTS @ $8.25 per plant 109 QUANTITY OF PLUGS @ $2.00 per plug 40 ESTIMATED COST OF PLANT MATERIAL AND LABOR $979.25 ESTIMATED COST OF MONITORING (3 YEARS@ $500/yr) $1,500.00 ESTIMATED COST OF MAINTENANCE (3 YEARS@ $500/yr) $1,500.00 0 (4 -Qv 1 rzi I_D PK -Me , 4 979.2�s TOTAL ESTIMATED COSTS (Plant Material and Labor) $979.25 1,5-ozy- "-u 120% OF TOTAL ESTIMATED COSTS $1,175.10 § 3) 9 7� . z,s- Plant prices are based on a quote from Van den Akker's Landscaping and include �ZL/©A- labor. PROJECT MONITORING PROGRAM Requirements for monitoring project: 1. Initial compliance report 2. Annual site inspections (in the fall) for three years 3. Annual reports (One report submitted in the fall of each monitored year) Purpose of Monitoring: The purpose of monitoring this project is to evaluate the success of the enhancement plantings. Success will be determined if monitoring shows that at the end of three years the performance standards are being met and that habitat values in the enhancement areas are equivalent to similar ecosystems in the immediate area. Inspection Schedule: Upon completion of the mitigation project, an inspection by a qualified wetland biologist will be made to determine plan compliance. A compliance report (as -built) will be supplied to the City of Edmonds regarding the completeness of the project. Condition monitoring of the plantings will be done by a qualified wetland biologist in the fall annually for the three-year monitoring period. A written report describing the monitoring results will be submitted to the City of Edmonds shortly after the fall inspection of each monitored year. Final inspection will occur three years after completion of planting. The contracted wetland professional will prepare a final report as to the success of the project. Definition of Success / Performance Standards: The enhancement areas shall support at least 80% survivorship, and at least 80% areal coverage of the native plants set forth in this plan by the end of three years. The species mix should resemble that proposed by the planting plans, but strict adherence to obtaining all of the species shall not be a criterion for success. Reproduction of volunteer native species may be used to establish areal coverage requirements. If a given area contains more than 10% areal coverage of invasive, non-native species within the planting areas, the enhancement shalt not be considered successful for that area. 7 MAINTENANCE The enhancement areas will require periodic maintenance during the monitoring period. These will be maintained at least one time during the spring and fall for each of the three monitored years, or as needed to assure the success of the mitigation project. Maintenance may include, but will not be limited to, removal of invasive vegetation (by hand or chemical means as necessary), thinning of volunteer red alder and black cottonwood to 10 -foot centers, replacement of plant mortality, and/or the replacement of mulch for each maintenance period. Chemical control, if necessary, shall be applied by a licensed applicator following all label instructions. The temporary irrigation system will be maintained for at least two years or as necessary to achieve firm establishment of the planted species. PERFORMANCE GOALS The goal of this mitigation plan is to establish a self sustaining natural wetland system with supporting buffers. The mitigation area will become a functioning portion of the larger stream and wetland system to the south and help to support an overall complex natural environment. CONTINGENCY PLAN If more than 20% of the plants are severely stressed during any of the inspections, or it appears more than 20% may not survive, additional plantings of the same species or, if necessary, alternative species may be added to the enhancement areas. If this situation persists into the next inspection, a meeting with a representative for the City of Edmonds, the consulting wetland biologist and the property owner will be scheduled to decide upon contingency plans. Elements of the contingency plan may include, but will not be limited to more aggressive weed control, expansion of the irrigation system, plant mortality replacement, species substitution, fertilization, and/or soil amendments. USE OF THIS WETLAND MITIGATION PLAN This Wetland Mitigation Plan is supplied to Michel Construction as a means of mitigating critical area impacts, as required by the City of Edmonds during the permitting process. This report is based largely on readily observable conditions and to a lesser extent, on readily ascertainable conditions. No attempt has been made to determine hidden or concealed conditions. Reports may be adversely affected due to the physical condition of the site and the difficulty of access which may lead to observation or probing difficulties. The laws applicable to wetlands are subject to varying interpretations and may be changed at any time by the courts or legislative bodies. This report is intended to provide information deemed relevant in the applicant's attempt to comply with the laws now in effect. The work for this report has conformed to the standard of care employed by wetland ecologists. No other representation or warranty is made concerning the work or this report and any implied representation or warranty is disclaimed. Wetland Resources, Inc. rfl L is Emen r Senior Wetland Ecologist WE REFERENCES City of Edmonds Code Chapter 20.158 Critical Areas. Classification of Wetlands and Deepwater Habitats of the United States. FWS/OBS- 79/31. December 1979. U.S. Department of the Interior, Fish and Wildlife Service. Washington, D.C. Corps of Engineers Wetlands Delineation Manual, 1987. Technical Report Y-87-1. Environmental Laboratory. U.S. Army Engineer Waterway Experiment Station. Vicksburg, MS. Soil Survey of Snohomish County Area Washington United States Department of Agriculture, Soil Conservation Service (1978). National List of Plant Species that Occur in Wetlands, Northwest Region. 1996. U.S. Department of the Interior, Fish and Wildlife Service. Washington, D.C. Washington State Wetlands Identification and Delineation Manual. Washington State Department of Ecology. Publication #96-94. March 1997. u-, , w z U. I w L5 w Zw < w uj to 3: oz n m co co Wo ko = 0 C) Z uj LNLI aE baN u-, , w z U. I w L5 w Zw < w uj to 3: oz n m co co Wo ko = 0 C) Z uj LNLI aE co jT rtP0 U ` D cc) fF Z < EA- aE 2 E jT rtP0 fF Z 0 :E 0 E EA-