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Shoreline Erosion Site Inspection Report: Sherwood Forest Property Maryland Department of Natural Resources Chesapeake and Coastal Service Shoreline Conservation Service Inspection Date: July 20, 2016 Point of Contact: Bill Chandler (410) 624-6957 [email protected] Site Location: 842 Beach Dr. Sherwood Forest, MD 21405 Cottage 842 Severn River Anne Arundel County Site Inspectors: Bhaskar Subramanian Shoreline Conservation Service Program Manager (410) 260-8786 / (443) 454-1638 [email protected] Rebecca Swerida Shoreline Conservation Service Project Manager, Biologist (410) 353-7003 [email protected] Further Program Information: http://dnr2.maryland.gov/ccs/Pages/livingshorelines.aspx Purpose of Inspection: To inspect eroding shoreline areas of concern and to provide technical assistance and recommendations. Tawes State Office Building – 580 Taylor Avenue – Annapolis, Maryland 21401 410-260-8DNR or toll free in Maryland 877-620-8DNR – dnr.maryland.gov – TTY Users Call via the Maryland Relay Fetch: Direction Northwest North Northeast East Distance (Miles) 2.11 0.52 0.52 0.59 Site fetch distances. Approximate Shoreline Length: 750 feet Approximate Distance to Infrastructure: 75 feet Approximate Water Depth: 3 feet depth 20 feet from the shore Historic Rate of Erosion (Mean): 0.36 feet per year (Slight Erosion) Line Color Purple Green Yellow Basemap Year 1845 1965 1994 2014 Increment Distance (ft) 61.5 22.5 - Note: Historical shorelines are most accurate in areas of open water. Description of Shoreline: The shoreline of concern is approximately 750 feet in length and faces northeast along the Severn River near Round Bay. The shoreline shows historical evidence (based on Maryland Coastal Atlas historical shoreline data) of active erosion at a mean rate of less than one foot per year, a rate classified as slight erosion. The historical shoreline data also indicated that the shoreline hardening in place has slowed erosion sometime between 1965 and 1994, although erosion has since continued behind the structure. The shoreline consists of a low, eroding bank backed by some area of vegetated buffer, including native species such as three square rush (Scirpus americanus), marsh hibiscus (Hibiscus moscheutos) and mowed grass lawn. Some invasive phragmites (Phragmites australis) was also noted. A low riprap/revetment structure constructed of loosely placed small stone is currently in place along most of the shoreline with areas of erosion and depressions on the landward side. Above the bank there is a fairly flat landscaped grass lawn and a paved road approximately 75 feet from the shoreline and a higher elevation residential area beyond. A wooden finger pier, boat ramp and kayak rack is located on the western edge of the shoreline. The water depth to approximately 20 feet off shore is very shallow, estimated to only 3 feet and the substrate appears sandy. A dense bed of submerged aquatic vegetation (SAV), specifically widgeon grass (Ruppia maritima), sago pondweed (Stuckenia pectinata) and perfoliated pondweed (Potamogeton perfoliatus) was observed and has been aerially mapped 37 to 165 feet from the shoreline. Neighboring areas have also been hardened with bulkheads, stone revetments and groins. An effective living shoreline project has been installed on the eastern side of the property. Overland flow runoff was identified as a problem, particularly in areas where the vegetated buffer is fairly thin. Stone lined drainage swales also flood regularly. Wide view of portion of shoreline, note limited buffer, Example of eroded area behind riprap. Previously installed bulkhead, stone revetment and groins. Newly installed stone revetment. Portion of effective, in place living shoreline. Stone lined drainage swale. Recommendations: A combination of over land flow and storm event wave activity is most likely the cause of erosion at this shoreline. It was determined that the site’s erosion could be controlled with a Living Shoreline project while creating habitat and maintaining natural processes. Fill and Vegetation Plan The erosion immediately behind the stone rip rap structures can be temporarily controlled by filling the existing holes and vegetating the area with stabilizing native plants. The depressed eroded areas should be lined with woven, 70 sieve filter cloth (available at hardware and landscaping stores). More shallow depressed areas can then be filled with layers of mulch and sand. Deeper areas should be filled with segments of coir coconut fiber bio-logs, staked in place. A layer of mulch and sand should be filled behind the coir log. The coir logs are designed to hold that sand in place for 4 to 5 years until the logs naturally biodegrade and the root mats of growing vegetation will stabilize the sediment. Bio-logs, as well as many shoreline plants, are available from the Pinelands Nursery in Columbus, NJ (609-291-9486), among other vendors. Locally, the Providence Center in Arnold is an excellent source of many shoreline plants, 410-766-2212 ext. 411. The area (at least 3 to 4 feet) behind the stone riprap or coir logs should be vegetated with native stabilizing plants. Switchgrass (Panicum vigatum) is the most highly recommended species for a situation like this. It has very strong fibrous roots that grow seven times as long as the above ground material. These grasses very effectively stabilize shoreline sediments and are attractive, often used decoratively, and provide the environmental functions listed above. Plugs can be purchased from most nurseries, including those listed below, and should be planted in 2 to 3 offset rows every 3 feet in spring or early summer. The plants will grow quickly and natural fill in the rows most likely within one growing season. Switchgrass can grow quite tall, up to 7 feet, but can be trimmed to as short a height as 3 feet. Feel free to design the planted area to your desired aesthetics including features like walking paths etc. There are many more appropriate grass and shrub species for shoreline stabilization that could be incorporated into the planted area if more species diversity is desired: Little bluestem (Schizachyrium scoparium), deertongue (Dichanthelium clandestinum), big bluestem (Andropogon gerardii), coastal pepper bush (Clethra alnifolia), buttonbush (Cephalanthus occidentalis), partridge pea (Chamaecrista fasciculata) and wild indigo (Baptisia tinctoria). Before any work is done on the shoreline, it is a good idea to notify the county Critical Area Program (410-222-7485). Upland Stabilization Plan The upland run off and drainage portion of the shoreline erosion problem can be managed through strategic vegetation and the installation of drainage control structures. The existing vegetation on the sloping bank has clearly helped to provide a buffer that has slowed run off and increased percolation of water through the soil. The buffer can be enhanced with the addition of plant species with especially extensive and strong root systems that will help to stabilize the sediment and hold the bank together, such as those listed above. If dead or dying trees must be removed on the slope, the tree should be cut so that the stump and root system remain in place. The upland run off can further be controlled through vegetated bioswales and/or rain gardens. These structures consist of small raised areas that will route runoff water to a designated area where it can flow into layers of sand, mulch and soil, or sometimes cobbles and stones. Those biorention area are specially designed to absorb water and should be vegetated by moisture tolerant plants. There is a huge amount of diversity in native Maryland plants suitable for rain gardens and vegetated bio-swales. Here are a few suggested species: northern lady fern (Athyrium filix-femina), broomsedge (Andropogon virginicus), white turtlehead (Chelone glabra), joe pye weed (Eupatorium fistulosum), mist flower (Conoclinium coelestinum), swamp azalea (Rhododendron viscosum), spicebush (Lindera benzoin) and winterberry (Ilex verticillata). A publicly available technical guide to rain garden installation called “Rain Gardens Across Maryland” produced by the Maryland Coastal Bays Program is an excellent resource. The Anne Arundel county Soil Conservation District are experts in the field of upland run off control and should be contacted for further information. Please contact John Czajkowski District Manager [email protected] 410-571-6757 ex 114 Low Profile Stone Sill Although the stone riprap revetment structure has reduced overall erosion of the shoreline, it has been clearly overtopped by storm event and boat wake waves and impacted by over land flow. Erosion can be more effectively controlled, valuable habitat created and more of a buffer to shoreline flooding created through the installation of a low profile stone sill living shoreline design. This design option would include the installation of a segmented stone sill structure built parallel to the shoreline approximately 35 feet channelward from the shoreline. These structures would be trapezoidal in cross section and only about as high as the mean high tide level. A wedge of sand (made up of material with a low fine particle content) would be placed at a 10 to 1 slope on the landward side of the stone structures. The sand wedge would then be vegetated to create and low and high marsh habitat and stabilize the sediment. Salt meadow hay (Spartina patens) would be planted above the high tide line where the plants would only be inundated occasionally to form high marsh habitat and smooth cord grass (Spartina alterniflora) would be planted between the high and mid tide lines to form low marsh habitat. Plugs of each plant would be planted in the spring or early summer in offset rows at 18 inch intervals. If desired, biodiversity could be increased in the marsh habitat by taking advantage of the salinity of the area and some of the following brackish mars plants: annual wildrice (Zizania aquatica), arrow arum (Peltandra virginica), river bank wildrye (Elymus riparius) and common rush (Juncus effusus). Upon request, I can recommend many more appropriate species to enhance the marsh habitat or create a “shoreline garden”. Costs can be controlled by reusing the stone making up the existing riprap structures, although larger stone would be necessary to cap off an effective structure. The estimated cost of this design is $300 to $400 per linear foot, for 750 feet resulting in a conservative total estimated cost of $300,000. The marsh habitat created and enhance would be protected by the stone sills while remaining accessible by wildlife (ex. Horseshoe crabs, turtles, or kayaks!) through the “windows” between the structures. Invasive Phragmites Control Information concerning the invasive wetland grass species Phragmites australis can be found at the following website: http://dnr2.maryland.gov/wildlife/Pages/plants_wildlife/Phragmites.aspx This is a very aggressive species and is not native to Maryland and is considered noxious due to its ability to quickly out compete native species and create dense, single species stands. Phragmites are considered inferior to native marsh grasses as they do not provide effective wildlife habitat, biodiversity, sediment stabilization or many of the other ecological services comparable to native species. A combination of chemical and physical control methods are recommended to remove the phragmites present on your shoreline and prevent future reestablishment. The two most commonly used phragmites management herbicides are glyphosate (Rodeo®, Aquamaster® and others) and imazapyr (Habitat®). Imazapyr is considered more effective overall, however, it may negatively impact all other plants in the area of application and remains active in the soil for an extended period of time. Glyphosate products are often less expensive and do not persist in the soil, but must be strategically applied in the late summer or fall to the seed heads of the plant. For further information, please contact: Waterfowl Habitat Specialist – Donald Webster MD DNR – Wildlife and Heritage Service 828B Airpax Road, Suite 500 Cambridge MD 21613 410-221-8838(ext.103) [email protected] Funding Options Some grant options may be available through the MD DNR Chesapeake and Atlantic Coastal Bays Trust Fund. This grant opportunity greatly emphasizes nutrient and sediment reductions to the Chesapeake Bay watershed and public benefit to shoreline ecosystems. Often, living shoreline projects are very beneficial to shoreline ecosystems, but may not reduce a large enough portion of nutrient additions to the watershed compared to other best management practices to be competitive. Details can be found here: http://dnr2.maryland.gov/ccs/Pages/funding/trust-fund.aspx. The Chesapeake Bay Trust Fund non-profit organization also offers a restoration and outreach grant program that has been successfully applied to community living shoreline projects in the past. Details can be found here: http://www.cbtrust.org/site/c.miJPKXPCJnH/b.5457271/k.C58E/Grants.htm. Also, the MD DNR Shoreline Conservation Service offers a 0 interest loan program for living shoreline projects which may be used independently or in conjunction with one of the above grants. The 0 interest loan program would work with Sherwood Forest as a targeted community and create a Shoreline Erosion Control Special Tax District with the help of Anne Arundel County. For more information, see the following website: http://dnr2.maryland.gov/ccs/Pages/livingshorelines.aspx. Additional Comments Submersed aquatic vegetation (SAV) beds are considered high priority habitat in the Chesapeake Bay because of the extremely valuable ecosystem services that they provide for the health of the Bay at large. As a result, shoreline construction or disturbance is restricted in areas that have had aerially mapped SAV beds during the past 5 years. The presence of mapped SAV beds in the area of the Sherwood Forest shoreline does not exclude the possibility of a living shoreline project, however it will impact the potential design options and should be kept in mind. It is important to avoid direct disturbance to the SAV habitat during potential living shoreline design and construction to maintain their ecosystem health. Design images: Example image of switchgrass (Panicum virgatum) Figure illustrated by Dede Christopher, Tennesee Valley Authority, Benefits of Riparian Zones Example image of salt meadow hay (Spartina patens) Example image of smooth cordgrass (Spartina alterniflora) Example image of phragmites (Phragmites australis) Shoreline Plant Nurseries: Pinelands Nursery Don and Suzanne Knezick 323 Island Road Columbus, NJ 088022 (609) 291-9486 Shore Solutions Nursery Connie Zinter P.O. Box 487 Cordova, MD 21625 (410) 820-6868 Environmental Concern, Inc. Suzanne Pittenger-Slear P.O. Box P St. Michaels, MD 21663 (410) 745-9620 Wicklein’s Aquatic Farm & Nursery Erik Wicklein 1820 Cromwell Bridge Road Baltimore, MD 21234 (410) 823-1335 Water’s Edge Nursery Co. Scott Haschen 6526 Dion Road Federalsburg, MD 21632 (410) 829-3723 Providence Center Inc. Laurie Collins 370 Shore Acres Road Arnold, MD 21012 (410) 544-2664 Angelica Nurseries Inc. 11129 Locust Grove Road Kennedyville, MD 21645 Lilypons Water Garden Margaret Koogle 6800 Lily Pons Road (410) 928-3111 Adamstown, MD 21710 (800) 999-5459 Shoreline Contractors: Waterfront Preservation Inc. Donny Burgess 1110 Old County Rd. Severna Park, MD 21146 (410) 703-7211 Dissen & Juhn LLC Gilbert Dissen 101 Log Canoe Circle, Ste J Stevensville, MD 21666 Phone: (410) 604-1802 Atlantic Shoreline Doug Jordan 25515 Golt Farm Lane Goldsboro, MD 21636 (410) 490-1981 Shoreline Design, LLC Wes Matheu 637 Shore Drive Edgewater, MD 21037 (410) 956-4662 Heinsohn Contracting, Inc. Gerd Heinsohn 222 Severn Ave., Suite 45, Building 10-8 Annapolis, MD 21403 (410) 263-1852 Envirens. Inc. Michael Hollins 21221 Mikules Manor Lane Freeland, MD 21053 (410) 299-6898 Corman Marine Construction Sean MacNeal 711 East Ordnance Road Suite 715 Baltimore, MD 21226 (410) 439-9700 Edwin A. & John O. Crandell Inc. David Harris 733 Crandell Road West River, MD 20778 (410) 867-0200