Blackjack Creek Mitigation Site Restoration and Management ... ?· Blackjack Creek Mitigation Site Restoration…
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<ul><li><p>Blackjack Creek Mitigation Site </p><p>Restoration and Management Plan </p><p>Wildlands of Washington, Inc. </p><p>June 2006 </p><p>Note from the author: </p><p>This document was prepared for Wildlands of Washington, Inc., a mitigation banking </p><p>company based in western Washington State. </p><p>Preparation included: </p><p> Site research into the existing site conditions (soils, vegetation, topography); </p><p> Preparation of the proposed mitigation design; </p><p> Close communication with the client to properly capture project intent; </p><p> Several iterations of draft submittals and incorporation of revisions based on client </p><p>comments; </p><p> Preparation of supporting tables (figures and appendices provided by others); and </p><p> Finalization of document for submittal to state and federal agencies (e.g. U.S. </p><p>Army Corps of Engineers, WA Department of Ecology). </p><p>Because of this documents proprietary nature, the full table of contents is shown, but only </p><p>select sections are provided. </p><p>Janice Cessna </p></li><li><p>June 16, 2006 Blackjack Creek Mitigation Site </p><p>Wildlands of Washington, Inc. Restoration and Management Plan </p><p>1</p><p>Table of Contents </p><p>Executive Summary ...3 </p><p>Project Purpose4 </p><p>Mitigation Approach...4 </p><p>Mitigation Site Goals and Objectives...5 </p><p>Mitigation Site Description5 </p><p>Site Details .5 </p><p>Site Selection Rationale ...6 </p><p>Constraints of the Site ..5 </p><p>Existing/Baseline Conditions .6 </p><p>Site Plan and Design ...11 </p><p>Description .5 </p><p>Water Regime 6 </p><p>Grading Plans ...5 </p><p>Planting Plans ...6 </p><p>Wetland Functions Comparison.4 </p><p>Mitigation Acreages and Perimeter Buffer 5 </p><p>Performance Standards ..15 </p><p>Monitoring Plan ...18 </p><p>Monitoring Schedule...18 </p><p>Monitoring Methods20 </p><p>Maintenance, Monitoring and Contingency Plans ..21 </p><p>Financial Assurances and Site Protection..21 </p><p>References ..22 </p></li><li><p>June 16, 2006 Blackjack Creek Mitigation Site </p><p>Wildlands of Washington, Inc. Restoration and Management Plan </p><p>2</p><p>List of Tables Table 1 Proposed Mitigation Acreage without Perimeter Buffer XX </p><p>Table 2 Proposed Mitigation Acreage with Perimeter Buffer ....XX </p><p>Table 3 Monitoring Schedule for Blackjack Creek Mitigation Site .19 </p><p>List of Figures Figure 1 - Vicinity Map </p><p>Figure 2 - Site Overview Map </p><p>Figure 3 Zoning Map </p><p>Figure 4 - Wetland Delineation </p><p>Figure 5 - Groundwater Well Locations </p><p>Figure 6 - Natural Resource Conservation Service Soils </p><p>Figure 7 - FEMA Floodplains </p><p>List of Appendices Appendix A Existing Conditions map </p><p>Appendix B Cultural Resources Report by Landau Associates </p><p>Appendix C Phase I Environmental Site Assessment by Landau Associates </p><p>Appendix D Wetland Delineation Report by Landau Associates </p><p>Appendix E Blackjack Creek Mitigation Site groundwater data </p><p>Appendix F Grading Plan, Planting Plan, and Details sheets </p><p>Appendix G Wetland Rating Form: Blackjack Creek Mitigation Site After Implementation </p></li><li><p>June 16, 2006 Blackjack Creek Mitigation Site </p><p>Wildlands of Washington, Inc. Restoration and Management Plan </p><p>3</p><p>Water Regime The proposed Mitigation Site will experience the same flooding frequency and duration that </p><p>occurs now. Groundwater will remain the primary year-round water source with surface flow </p><p>from Blackjack Creek contributing a significant portion only in the winter season. Therefore, no </p><p>water rights are needed. No mass grading, culvert installation, or water control structures are </p><p>proposed in the project design. </p><p>As described earlier in the existing conditions, the dredged creek spoils currently serve as a </p><p>physical barrier to initial floodwaters within Blackjack Creek. By removing the spoils, the creek </p><p>will have an entirely open connection to its floodplain within the project site. Some spoils, </p><p>however, will be left in place as upland islands for greater habitat diversity. These will be </p><p>approximately twenty-five square feet (approx. 5 by 5) or less and scattered intermittently </p><p>along the creek length with approximately several hundred feet between each. </p><p>Removal of drain tiles and plugging of drainage ditches will restore the natural hydrologic cycle </p><p>within the site by discontinuing the current expedited drainage routes. The groundwater table </p><p>will likely rise closer to the ground surface, becoming more readily available throughout the year </p><p>and sustaining a saturated perennial wetland system. Existing herbaceous species dominated by </p><p>facultative grasses will transition to domination by obligate sedges and rushes. </p><p>Because no volume or flow analysis has been conducted on Blackjack Creek, a quantification of </p><p>the potential water table rise is not presented. However, the review of the existing conditions </p><p>within the southeast forested wetland as discussed earlier in the existing conditions section offers </p><p>a glimpse of the future habitat. In this area, saturation is at or within a few inches of the ground </p><p>surface year-round, as demonstrated in Landau Associates wetland delineation report. </p><p>Additionally, small pockets of water ponds in low spots during the winter months. </p><p>The groundwater monitoring wells will be kept in place and maintained during the </p><p>implementation of this Restoration and Management Plan, as well as through the duration of the </p><p>monitoring and maintenance periods. The wells will likely be preserved and occasionally </p><p>monitored for a time after final project acceptance by responsible agencies. </p><p>Grading Plans Proposed grading will be limited to the removal existing spoils along Blackjack Creek and </p><p>removal of the existing site access road east of the creek bridge. Both areas will supply fill </p><p>material for use on-site as ditch plugs and upland hummocks. This process involves </p><p>approximately 2000 cubic yards of material. Because the volume of available spoil material will </p><p>not be sufficient to facilitate filling of all on-site ditches, plugs will only be placed at key </p><p>intersections with Blackjack Creek, thereby blocking site drainage and impounding water within </p><p>the site interior. However, the southwest ditch and the long perimeter ditch running along the </p><p>south and east boundary, will remain intact since impacting their function would have significant </p><p>impacts to neighboring properties. In the future, should Wildlands succeed in acquiring the </p><p>adjacent parcels, these ditches will be abandoned. </p></li><li><p>June 16, 2006 Blackjack Creek Mitigation Site </p><p>Wildlands of Washington, Inc. Restoration and Management Plan </p><p>4</p><p>Remaining spoil material will be used to create hummocks of varying dimensions across the </p><p>rehabilitated wetland. Proposed locations and approximate dimensions are depicted on the </p><p>Grading Plan and Details (Appendix F). Also depicted is the removal of all culverts and concrete </p><p>slab bridges. The existing bridge crossing Blackjack Creek will remain for site access purposes. </p><p>All extracted items will be disposed of offsite. No major invasive vegetation removal is planned </p><p>during construction. Any incidental invasive species material removed during project </p><p>implementation will be removed from the site. </p><p>After the grading and demolition work is completed, removal of the drain tiles will occur. </p><p>Unfortunately, the tiles precise locations are not known. In order to find and successfully </p><p>remove these, a small dozer or similar machine with ripping tines will make passes parallel to </p><p>Blackjack Creek on both sides. No equipment or surface disturbance will occur within ten feet of </p><p>the top of bank. </p><p>Focusing the ripping area to this vicinity will limit large-scale disturbance to the site by limiting </p><p>the ripping to an area already disturbed by grading activities. While the tiles will remain across </p><p>the remaining Mitigation Site, their function will be halted through this localized disruption and </p><p>removal. Any tiles brought to the surface will be collected and disposed offsite. </p><p>Planting Plans Care will be taken during implementation of the grading plan elements to minimize existing </p><p>vegetation disturbance. There will be no or very limited impacts to existing scrub-shrub or </p><p>forested communities. However, disturbance to herbaceous vegetation will occur during the spoil </p><p>relocation described above. Any healthy wetland herbaceous species that can be reasonably </p><p>salvaged will be removed from the excavation area and either returned after grading is complete, </p><p>or transplanted to a similarly disturbed location elsewhere on site. </p><p>Aside from replacing salvaged material, Wildlands will also plant native species that are known </p><p>to occur in the area and are appropriate for the site. Herbaceous emergent wetland and grass </p><p>species will be installed for immediate post-construction erosion control and wetland habitat </p><p>while woody vegetation matures. Species include Slough sedge (Carex obnupta), Tufted </p><p>hairgrass (Deschampsia caespitosa), and Scirpus lacustris (Softstem bulrush). </p><p>As for woody species, the existing scrub-shrub and forested wetland communities on site and </p><p>within the surrounding landscape indicates a mosaic of similar vegetation would be appropriate. </p><p>Existing topography and groundwater have created wetter areas in the middle and north areas of </p><p>the site. These will be planted with a scrub-shrub community dominated by Sweet gale (Myrica </p><p>gale), Western bog laurel (Kalmia macrophylla), and Labrador tea (Ledum groenlandicum). </p><p>Other species include Willow (Salix spp.), Salal (Gaultheria shallon), False azalea (Menziesia </p><p>ferruginea), and Swamp rose (Rosa pisocarpa). Shrub species will be installed at a density of </p><p>500 stems per acre. </p><p>The drier areas, primarily to the south and southeast, will be vegetated with a Western redcedar </p><p>(Thuja plicata) and Western hemlock (Tsuga heterophylla) dominated community. It will be </p><p>planted at 500 stems per acre including 275 trees and 225 shrubs per acre. </p></li><li><p>June 16, 2006 Blackjack Creek Mitigation Site </p><p>Wildlands of Washington, Inc. Restoration and Management Plan </p><p>5</p><p>This community will also be planted on the hummocks scattered within the scrub-shrub area, </p><p>however, fewer shrub species will be included. The total density planted per acre will also be </p><p>500, but the amount of trees and shrubs will be 305 and 195 per acre, respectively. </p><p>Vegetation sources will vary depending upon vegetation type. Herbaceous emergent and grass </p><p>species will be installed using seed. Woody vegetation will be container stock, bare root, and/or </p><p>live stakes. Choice of plant material type and size will depend upon availability of plant material </p><p>at the time of implementation. However, plant sizes for the container stock will be restricted to a </p><p>combination of four-inch pots/tree tubes and one-gallon containers. Live stake installation will </p><p>be limited to willow and cottonwood species, with the majority installed along Blackjack Creeks </p><p>banks. </p><p>The Planting Plan with planting and seeding schedules can be reviewed in Appendix F. A </p><p>general use seed mix will be applied on all areas disturbed by grading at rate of 40 pounds/acre. </p><p>Harrowing or roughing of the seeding surface after installation will be done to limit predation by </p><p>fauna. At least some natural recruitment is expected from existing alder, cottonwood, and willow </p><p>species on the site. Volunteers have been accounted for in the Performance Standard section </p><p>below. No irrigation or soil amendments will be installed or utilized; during years of normal </p><p>precipitation, reliance on existing groundwater will be sufficient for vegetation establishment. </p><p>The perimeter buffer around the Mitigation Site boundary will receive the same rehabilitation </p><p>and enhancement actions as the interior mitigation area including vegetation with the same </p><p>species and densities. As-built plans documenting post-construction site conditions will be </p><p>submitted to the reviewing agency in January 2008. These plans will document grading, planting, </p><p>seeding, and any other implementation requirements per the approved Restoration and </p><p>Management Plan. </p><p>Wetland Functions Comparison As part of Landau Associates wetland delineation (Appendix D), a rating was completed on the </p><p>Mitigation Sites existing wetland complex. This included all forested, scrub-shrub, and </p><p>emergent components of the sites wetland. The Depressional and Flat Wetland section of the </p><p>Washington State Wetlands Rating System for Western Washington (Ecology 2004) was used to </p><p>quantify the wetland functions. Overall, it rated as a Category III with a total of 44 points. </p><p>Landau explains this score is influenced not only by intensive cattle grazing on and off-site, but </p><p>also by low vegetation structure and community interspersion. </p><p>Similarly, a wetland rating was completed on the proposed Mitigation Sites rehabilitated and </p><p>enhanced wetland complex at the end of its 5-year implementation and monitoring schedule as </p><p>outlined in later sections. This assumes that the entire site will be constructed as a whole, which </p><p>may or may not occur depending on mitigation needs within the Blackjack Creek area. </p><p>The same Depressional and Flat Wetland rating section was utilized, although the HGM Class is </p><p>slightly different. With the restored floodplain connectivity and hydrologic processes from the </p><p>proposed removal of existing creek side spoils, HGM becomes a Depressional with Riverine </p></li><li><p>June 16, 2006 Blackjack Creek Mitigation Site </p><p>Wildlands of Washington, Inc. Restoration and Management Plan </p><p>6</p><p>versus the original simple Depressional class. Regardless of the slight change, the Mitigation Site </p><p>was rated as whole wetland complex using the Depressional and Flat Wetland section. A copy of </p><p>the wetland rating worksheets can be found in Appendix G. The proposed complex rated as a </p><p>Category II with a total of 69 points. </p><p>Monitoring Plan Monitoring Schedule A combination of formal and informal monitoring of the proposed compensation site will occur </p><p>through the fifth year following construction (Year 5) of each individual compensatory </p><p>mitigation area. Informal monitoring will occur periodically to document changes in the site </p><p>over time and to provide information to the natural resource entity responsible for long-term site </p><p>management. Formal monitoring will occur in Years 1 and 3 while informal monitoring may </p><p>occur periodically every year. Informal monitoring will occur in addition to formal monitoring </p><p>in some years. More frequent informal monitoring may be warranted because of specific site </p><p>conditions or site-specific goals. For example, greater frequency may be necessary to track the </p><p>re-colonization of invasive weeds or report results from management treatments that are needed. </p><p>The site will be monitored according to the schedule listed in Table 3. </p><p> Table 1. Monitoring Schedule for Individual Mitigation Cells (authors note abbreviated for client confidentiality) </p><p>Objective Measurement Year(s) When </p><p>Measured </p><p>1A. Grading and Hydroperiod </p><p>1 -4 . As-built topographic survey...</p></li></ul>
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