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HomeMy WebLinkAboutWetland Mitigation 994600303 Gary Olson Buffer Reduction and Enhancement Plan Parcel #994 600 303 April 2007 Prepared for: Gary Olson 61 Margaret Street Port Ludlow, WA 98365 .... J~i;} ". .'" 4"\~ l\rf.A 1\/ \~J> ~'\.j ~ :,~, t..~R t .~ , . \\ \'f\\\~~ ~t~ ~\~~t~~~\'~ \.,\}, . 3603 dixiellewellin@yahoo.com 98368 Gary Olson Buffer Reduction and Enhancement Plan Parcel # 994 600 303 April 2007 Table of Contents Introduction Project Proposal Enhancement Plan Existing Conditions Project Goals and Objectives Best Management Practices Revegetation Installation Maintenance and Weed Control Seeding to Stabilize Soils Irrigation Monitoring Plan Monitoring Methodology Monitoring Schedule Performance Standards Contingency Plans Summary Appendices Sheet #1 Revised Wetland Boundary Map Sheet #2 Buffer Reduction and Enhancement Plan Plant List and Landscape Specifications Installation Specifications and Recommendation with Seed Mix Gary Olson Buffer Reduction and Enhancement Plan Parcel # 994 600 303 April 2007 Introduction A Category I wetland was delineated by Olympic Wetland Resources, Inc on October 2006 on the neighboring property to the west of the Olson site. During a visit in March 2007, by a Jefferson County Critical Areas specialist, a slope wetland with flowing water was observed in the northern portion of the subject parcel. This wetland was not identified at the end of a dry summer during the October delineation. Further field investigation verified that the slope wetland connects hydrologically to the downslope wetland. The additional wetland edge on the Olson parcel was delineated on April 12, 2007 and is shown on the Revised Wetland Boundary Map included in the Appendix (Sheet #1). The 150-foot buffer as mapped from the October 2006 delineation covers the majority of the parcel. Additional buffer restrictions from the April 2007 delineation are minimal and a buffer reduction and enhancement plan will still be required. Project Proposal A sewage disposal system (Glendon Biofilter system) was designed by D.R. Strong Engineering for the southern portion of the parcel, which is within wetland buffers. Since there are no feasible alternatives a portion of the 150-foot buffer will need to be reduced to 100 feet thereby reducing the buffer by 2,500 sq. ft. Land disturbance from installation of this system is 1,250 sq. ft. and will require a 30-foot Downhill Protection Zone, which can be included within the buffer according to Mike McNichols Jefferson County Environmental Health Department. This buffer mitigation plan proposes to enhance 2,500 sq. ft. at a 1: 1 ratio within an area that has been previously impacted by filling and clearing. This system will service a proposed homesite on Margaret Street 250 feet to the south via a transport line across another parcel owned by Gary Olson. The transport line will cross under Joan Street and along the property edge where a wetland was identified during the April 2007 site visit. A dominance of wetland vegetation, wetland soils, and hydrology (surface saturation and ponded water) were identified on the northern 100' of the 150' long parcel. To minimize disturbance of the wetland during installation of the line a narrow ditch will be excavated with a hand operated ditch digger during the dry season. After the line is installed soils will be replaced to original elevations and native vegetation will be replaced so there will be no long term impacts to this wetland. Olson ButTer Reduction and Enhancement Plan Report File Number 2007-1015 . 1 Olympic Wetland Resources, Inc. April 2007 Enhancement Plan Mitigation requirements have been prepared to meet the standards outlined in the Department of Ecology. Guidance on Wetland Mitigation in the State of Washington State (April 2004). This enhancement plan summarizes functions and values of the existing wetland system, vegetation for restoration, maintenance and monitoring schedules, and performance standards. Existing Conditions The site for the septic system has been disturbed by previous land use activities and consists of non-native grasses and weedy species. The edge of the clearing is shown on the Revised Delineation Map. Beyond the edge of the clearing there is a mature forest with multiple structural layers containing diverse vegetation within this high quality wetland. There are numerous small stream channels with ponded water along the sloped hillside below Hwy. 104 and within the flat wetland on the neighboring parcel. These swampy areas consist of black organic soil. The transport line crosses through a depressional wetland that is dominated by a forest layer of Sitka spruce and cedars with an understory of salmonberry and water parsley. Fill has been added to this parcel south of Joan Street. Functions and values of this wetland are moderate due to the surrounding roads and residential developments. Project Goals and Objectives The goals and objectives for the septic site and the transport line wetland crossing are as follows: . to avoid all permanent impacts to the wetland; . to reduced buffer by 2,500 sq. ft. at the septic site location (from 150 feet to 100 feet in the eastern portion of the parcel) and revegetate the 2,500 sq. ft. of buffer within the cleared area; . to increase diversity of plant species with a dense planting of native species (20 trees and 25 shrubs); . to provide protective measures during the construction process to minimize impacts to wetlands or buffers (BMP's during and after construction); . to minimize impact from digging a trench though the wetland for the transport line and restoring the site to original elevations and conditions; . to remove and control non-indigenous plant species within the mitigation areas; . to guarantee the success of the project through maintenance and irrigation of planted species as needed; and . to document the success of the project and assure that the performance standards are met through an annual monitoring for 5 years. Monitoring will include inspection of the transport line crossing. Best Management Practices (BMP's) These Conservation Practices will be implemented at all times during and after construction. 1. Avoid or control soil loss and protect water quality from degradation caused by nutrients, animal waste, toxins, and sediment; and 2. Avoid or minimize adverse impacts to surface water and ground water flow, and circulation patterns; and Olson Buffer Reduction and Enhancement Plan Report File Number 2007-1015 2 Olympic Wetland Resources, Inc. April 2007 3. A void or control the movement of sediment and erosion control caused by land alteration activities. It is recommended that the project to be conducted during dry weather to minimize runoff. All soils should be stabilized with straw and re-seeded; and; 4. Avoid or minimize adverse impacts to the chemical, physical, and biological characteristics of critical areas; and 5. No fertilizers, pesticides, or other lawn chemicals will be applied to the yard or adjacent buffer vegetation. 6. A silt fence should be installed to guarantee that no sediments enter the wetland during construction. BMP's are those practices as defined by the Jefferson County, State of Washington Department of Agriculture, State of Washington Department of Ecology, State of Washington Department ofFish and Wildlife, conservation district, and other professional organizations. Revegetation Final location of recommended plant species should be determined when construction is complete. Recommendations for plant locations are included in the Appendix (Sheet #2, Buffer Reduction and Revegetation Plan). A plant list is included in the Appendix. The plan includes a list of native species that would be appropriate for this site. Soils will need to be amended with imported soils and compost for the success of planted species. Species in the plan are chosen to adapt to the surrounding conditions. Trees recommended for this enhancement plan include shore pines, quaking aspen, Douglas' fir, and red cedar. The shrub layer includes red osier dogwood, hazelnut, twinberry, Pacific ninebark, and red flowering current. A total of20 trees and 25 shrubs are included in this enhancement plan. Installation All plant material should come from healthy plants grown in containers as specified. It is desirable to obtain plants that are adapted to this region and propagated in local nurseries. Nursery specimens should be planted in dense groupings. In general, trees should be planted 6 to 8 feet apart and shrubs 3 to 5 feet apart; herbaceous species 6"to 8" apart. Native plant design encourages grouping of species in clusters to mimic the natural surroundings, rather than in rows or grids. Installing mulch circles (bark, wood chips, compost) to 3" deep and a minimum of3 feet in diameter around each tree and shrub is recommended. Mulch circles help woody specimens become established by preserving moisture and reducing competition for nutrients from grasses. Success rates of a restoration project are greatly improved when commercial tree protectors are used on newly planted trees and shrubs. With this added protection mortality is reduced during weeding and deer grazing. Maintenance and Weed Control The use of appropriate native species ensures that ongoing maintenance is minimized once the plants are established. All new plantings must become established to successfully out-compete aggressive non-native species. Alders should be controlled to allow the native trees and shrubs to become established. All invasive non-native plants should be controlled or removed. It is critical th~t the Himalayan blackberries, Scot's broom, and poison hemlock are controlled; they can easily out compete and cover planted species in one season. Olson Buffer Reduction and Enhancement Plan Report File Number 2007-1015 3 Olympic Wetland Resources, Inc. April 2007 Seeding to Stabilize Soils All areas of exposed soils along the project route will be re-seeded with the seed mix. The seed mix should be spread after the final grading from the construction is complete and all trees and shrubs are planted and mulched. Seed mix recommendations are included in the Appendix under the Installation Specification and Recommendations. Irrigation Irrigation may be required for the success of planted species through the dry summer months. In the low-lying areas of the site hydrology may be present year-round. If the planted species appear to be stressed in the summer months they must be irrigated. Trees and shrubs require a minimum of 1 inch of water per week or 2 inches every two weeks from July thorough September. Monitoring Plan Monitoring Methodology. Determining Survival Rates Using Monitoring Forms A monitoring form will be used to determine plant survivorship, species density, and general condition of planted species. This information will determine whether plant survivorship and percent cover provided are sufficient to meet the performance standards. Elements in the monitoring forms should include: . plant names (common and scientific), type (tree, shrub) and numbers planted at each site; . general condition of planted species (alive, stressed, dead); . percent survival of trees and shrubs; . species to be replaced; . contribution of volunteer species; . estimate of "desirable" plant species cover and "non desirable" plant species cover, and; . appearance and approximate location of non,;,native invasive species, which include Himalayan blackberries, reed canarygrass, Scot's broom and Canadian thistle. Documenting Wetland Changes Using Photographs Permanent photopoints will be established to document the changes of the vegetation layer over time. Over the course of the 5-year monitoring program, the growth and development of the plant communities should be discernible in the series of photographs. Photographs from all photopoints will be included in the annual reports. Monitoring Schedule Monitoring will be conducted by a professional wetland biologist. The monitoring program is to begin after the final planting is complete to ensure that healthy stock is installed. Monitoring will be conducted during the growing season in late June or early July and continue for 5 years. Olson Buffer Reduction and Enhancement Plan Report File Number 2007-1015 4 Olympic Wetland Resources, Inc. April 2007 Summary reports will be prepared annually and submitted to the Jefferson County Department of Community Development. The reports will consist of a general description and condition of the planted areas. Counts will be made of all species that need to be replaced and the location of undesirable weed infestations will be recorded. s M dM S h d I ample onltonng an alntenance c e u e Fall Spring Fall Spring Fall Spring Fall Spring Fall Spring Fall Maintenance Planting Maintenance* X X X X X Irrigation * X X X Replace plants as needed X X X X Monitoring Vegetation and Habitat X X X X X Photopoint X X X X X Annual Report X X X X X *lrrigation May through September; Weeding twice a year Performance Standards Monitoring will determine whether the performance standards identified in this mitigation plan are met. The proposed length of time for mitigation compliance is five years. This time period will allow for the planted and volunteer species to become established. Enhancement will be considered successful if the buffer plantings meet the following criteria: . Survivorship of tree and shrub species is expected to be 100% after the first growing season. All plants that do not survive the first year should be replanted. . The wetland buffer mitigation will be considered successful if 80% or greater of desirable cover is achieved and the plants are healthy and vigorous. Desirable species include volunteer native trees and shrubs (Nootka rose) and native and non-native pasture grasses. . No more than 15% invasive species should be present at any time during the monitoring process. Non-desirable species include Scots' broom, reed canarygrass, poison hemlock, thistle, (both Canadian and bull), and Himalayan blackberry. Contingency Plans The purpose of the contingency plan is to evaluate available alternatives if monitoring indicates that the project goal and objectives have not been achieved. Contingency plans will vary depending upon which goals have not been met and will apply to each specific mitigation activity. Appropriate corrective action will be recommended after the first year of the monitoring process and will include the following: . replanting of any dead vegetation in the first year and additional replanting if density goals are not met over the following four years; . increased maintenance, which may include additional watering and/or weeding; . additional protection to established buffers to compensate for the length of completion of mitigation if the density goals are not being met. Olson Buffer Reduction and Enhancement Plan Report File Number 2007-1015 5 Olympic Wetland Resources, Inc. April 2007 Summary A Category I wetland was delineated on or adjacent to the Olson property on October 2006 and April 2007. The 150 foot buffers from this wetland will restrict the placement ofa Glendon Septic System that will provide off-site sewage disposal for a proposed homesite on Margaret Street 250 feet to the south. The Glendon system has been relocated 15 feet to the east of the original plans submitted to the health department to further protect buffers (as approved by David Jensen D.R. Strong Engineering). Since the Downhill Protection Zone can be included within buffers less buffer will be compromised for this reduction plan. Buffers will need to be reduced from 150 feet to 100 feet along the eastern boundary of the site (2,500 sq. ft. reduction) since there are no other feasible alternatives. Construction will be conducted to ensure that there are no impacts to the wetland. The remaining buffer, within the clearing, will be enhanced at a 1: 1 ratio (2,500 sq. ft. enhanced). Twenty trees and twenty five shrubs will be installed and all bare areas will be reseeded. If the plan is implemented as outlined in this report there will be no permanent impacts to the wetland. A 250-foot transport line between the homesite and the septic system will need to cross under Joan Street and along the edge of a parcel with a depressional wetland. A small ditch will be excavated through the middle of the wetland. To minimize temporary wetland impacts the line will be excavated during the dry season with a small hand operated machine and the wetland will be restored to original conditions once the pipe is installed. Ground elevation will remain the same on both sides of the ditch and plants will be replaced once the ditched is filled. Monitoring for five years will be required to insure success of the planted species and conditions of the transport line. This report will be submitted annually to Jefferson County Department of Community Development. The final authority over this wetland determination and mitigation plan rests with the Jefferson County Department of Community Development. If there are further questions or planning requirements for this project please do not hesitate to call. Dixie Llewellin Principal Biologist, Olympic Wetland Resources, Inc. Certified for Wetland Delineation, 1987 Manual. Wetland Training Institute, June 1995. Olson Buffer Reduction and Enhancement Plan Report File Number 2007-1015 6 Olympic Wetland Resources, Inc. April 2007 rille: Revised Wetland Boundary Map Scale: Sheet Olympic Wetland Resources, Int Joan Street lH= 50' 856 50th Street Shine Washington Date: April 2007 #1 Port Townsend, WA 98368 Oient: Gary Olson 360 385-6432 61 Margaret Street Job#: 2007-1015 dixie@cablespeed.com Port Ludlow, WA 98365 Parcel #994 600 303 Al 100' DP # 1 . (;:~:;,:::..", 1 50' Buffer ~ N . DP #2 821 333 003 Joan Street 1RECE IVED APR 2 4 2n07 Delineated Wetland Edge 150' Buffer From Wetland Edge Flagged delineation markers . Data Points JEffERSON COUN OOOwetland locations and sizes are approximate; to establish exact points a formal survey is required Olympk Wetland Resources, Int 856 50th Street Port Townsend, WA 98368 360 385-6432 dixie@coblespeed.com luffer Reduction and Revegetaiton Pia Joan Street Shine Washington Oient: Gary Olson 61 Margaret Street Port Ludlow, WA 98365 Scale: 1"= 50' Sheet Date: April 2007 #2 Job#: 2007-1015 Parcel #994600303 100' ~ N Buffer Reduction AIeo_ 71 Aspen{S) * S.....Pine(IO) t Redc:edar(S) . Redosierdoswood{S) iN Haze.... IS) . 1\vinbeny (S) , Red FIowerin8 Currant IS) t Pacific ninebark IS) 821 333 003 I ITransport Line I Note: Glendon System has been moved - 1 5 feet to the northwest from the original plan to preserve the wetland buffer. Olson Plant List Enhancement Plan April 2007 '" ! ~ ~ ~ ~ " j I '" <</ . II t I (i \ I "" , fi. . > ," I Jr" " II..' '" I Vl I :-'1: ~ I I !tt. Pinus contorta Shore Pine container 2-5 gal 10' 10 Po ulus tremuloides Quaking aspen container 2-5gal 10 5 Thuja pUcata Red cedar container 2-5gal 10' 5 Total 20 , ~ ~.u.$~~ Cornus stolonifera Red osier dogwood container 2gal 5' 5 Corylus corn uta Hazelnut container 2gal 5' 5 Lonicera involucrata Twinberry container 2gal 5' 5 Phvsocarpus capitatus Pacific ninebark container 2 gal 5' 5 Ribes sanquineum Red flowering currant container 2 gal 5' 5 Total 25 Total Plants 45 Native Plant Nurseries Fourth Corner Nurseries, 3057 E. Bakerview Road Bellingham W A 98226 (360) 734-0079 Shore Road Nursery, 616 Shore Road Port Angeles, W A 98362 (360) 457-8482 Sound Native Plants, P.O. Box 7505, Olympia, WA 98507 (360) 943-7026 Woodbrook Nursery, 1620 59th Ave. Gig Harbor WA 98335 (206) 265-6271 Olympic Wetland Resources, Inc. Installation Specifications and Recommendations Fall Installation Planting should be installed between mid-September and mid-November, unless the new plantings can be watered throughout the summer. Plantings installed in the fall generally outperform those installed in the late winter or spring. Plants put in the ground in the fall have the advantage of an extended period for root growth before rapid top growth in the spring. In the fall, the soil is warmer and more aerated than in the spring and most plants experience active root growth during this time. The cool, cloudy days and frequent precipitation of fall and winter also provide ideal transplanting conditions. Until sufficient root systems develop, newly installed plants will undergo transplanting stress that can be exacerbated by hot sunny days. Fall and winter weather allows for reduced transpiration and provides ample moisture for the roots while the plant recovers from transplant shock. Root Disturbance Immediately before installation plants with broken, damaged, or twisted roots must be pruned. Matted or circling roots of containerized plantings must be pruned or straightened and the sides of the root ball must be roughened from top to bottom to a depth of approximately half an inch in two to four places. If circling roots are left, they may eventually girdle the plant as they grow and thicken in place. If the roots at the edge of the root ball are straightened and extended, they will have access to a greater volume of soil in the planting hole. Also, the roughened edges of the root ball will have better contact with the backfill soil. Disturbing and removing one-fourth to one-half of the roots in the outer inch of the root ball will damage only the most sensitive plants; most often, this treatment actually stimulates increased plant growth. Plant Depth The finished height of each plant's root ball will be slightly higher than that of the surrounding soil. The exception is for sandy soils, in which case the soil heights will be even. The top of the root ball will not be covered with backfill soil. A watering basin will be formed around each planting by building a berm of soil at least 30 inches in diameter. When planting a container-grown plant, the top of the root ball should not be covered with any other soil. Covering the root ball with soil, particularly if it has a finer texture than the potting or field-growing soil, will generally cause water to flow around the root ball instead of into it; root balls covered in this way may receive water only from below. To allow direct wetting of the root ball from above, install the plant so that the top of the nursery soil is slightly higher than the 1 surrounding soil level. If the soil is sandy, or of a large particle size, then the nursery soil should be level with the surrounding soil. A watering basin made of mounded soil around each planting will further help to catch water from above-the berm should be at least 30 inches in diameter surrounding a plant. Mulch placed within the basin and on the berm will limit moisture loss from the root ball and surrounding soil, but take care that it does not come into contact with the stem of the plant as rodents or pathogens living in the mulch may attack the bark. Re-seeding After the completion of the construction and planting projects, a seed mix is recommended to be spread on all bare areas as shown below. ~~.Re-seeding Recommendations and Quantities Scientific Name Common Name Percent lFestuca rubra var. commutata Red fescue 40% Ipechampsia cespitosa Tufted hairgrass 30% lLolium multiflorum Annual ryegrass 20% Trifolium hybridum Alsike clover 10% Planting recommendations: 25 lb. per acre Maintenance: Weeding and Irrigation The use of appropriate native species and careful planting ensures that the need for ongoing maintenance will be minimized. However, some maintenance is required to ensure that the young plants become established. It is recommended that weeding around new plants be conducted once or twice a year during the months of May and September for the first five years, and as often as needed after that. All Scot's broom, Himalayan blackberry, and thistle should be monitored and eliminated from the site. Irrigation may be required for upland species (vine maple, red-flowering currant, and pine) for the first three years or until plants are well established. Hand watering or irrigating with overhead sprinklers once a week should be adequate during the hot summer months. 2