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HomeMy WebLinkAboutGreg Berman Peer Review July 2023 1 | P a g e COASTAL PROCESSES SPECIALIST WOODS HOLE SEA GRANT | CAPE COD COOPERATIVE EXTENSION gberman@whoi.edu | gberman@barnstablecounty.org 508-289-3046 | 193 Oyster Pond Road, MS #2, Woods Hole, MA 02543-1525 July 18, 2023 TO: Yarmouth Conservation Commission CC: none FROM: Greg Berman, Coastal Processes Specialist (WHSG & CCCE) RE: Site report for Crowell Beach, Yarmouth, MA Background: Since the inception of the coastal processes position established within WHSG & CCCE, on- site and remote technical assistance on coastal processes has been and continues to be an on-going, effective technical information communication and dissemination tool. Technical assistance relating to coastal processes, shoreline change, erosion control alternatives, coastal landform delineation, potential effects of various human activities on coastal landforms, coastal floodplains, coastal hazards and hazard mitigation analyses, and dune restoration techniques provided in the field and remotely will continue to be provided on an as-needed basis. Site visits generally address site-specific coastal processes or coastal hazards related issues. Follow-up unbiased, written technical alternatives analyses are generally provided. 2 | P a g e Site Details: This report focuses on the property and land immediately adjacent to Crowell Beach, at the end of Crowell Road in Yarmouth (Figure 1). A NOI (dated 03/30/2023) has been submitted to the Yarmouth Conservation Commission for dredging and beach nourishment within the intertidal zone (MHW to MLW). Site plans (revised 06/28/2023) were submitted to accompany the NOI. This proposal is similar to a proposal submitted in 2016, for which a site report (11/28/2016) was generated. While the background information is not repeated in this report, the 2016 report is attached. Site Plan/NOI Details: The revised site plans (06/28/2023) include a cross section and indicate “190+/- CY of dredge material is to be placed in previously permitted nourishment areas”. It is not indicated if this will be a single event or if the applicant would like permission to dredge/nourish as needed during the entire duration of the Order of Conditions. Additionally, the project narrative in the NOI indicates that “The applicant would also like the ability to truck in compatible beach sand to use for beach nourishment in future years when dredging may not be needed." Neither the site plans or the NOI indicates the desired volume or frequency of this “trucked in sand”. If too much sand is applied to this area it may negatively impact the creek and marsh. As the project narrative indicates that one of the mitigation measures is that “The proposed project will improve conditions at the Site by restoring the coastal beach and improving the tidal flushing of the tidal creek.”, care should be taken as to not worsen the tidal flushing of the creek. Recommendations/Considerations for the 2023 NOI: • Most (if not all) of the Recommendations/Considerations from the 2016 report would still apply to this new NOI. • If any nourishment (from dredging and/or upland sources) occurs the Conservation Commission may want to require a monitoring plan that focuses on potential impacts to the tidal creek and salt marsh. • While a beach profile was added to the site plans (revised 06/28/2023), there is still no information on the plans or project narrative as to two very important aspects of this project: o How often does the applicant desires to dredge the creek and apply the material as beach nourishment. o The desired volume and frequency of the beach nourishment to be “trucked in”. • Any new sediment (i.e., the “trucked in” volume) to the area has the potential to create negative impacts by migrating into the creek and marsh. Even the dredged sediment used for beach nourishment may be transported more quickly than natural processes, but with much fewer potential impacts than new sediment being added to the system. • The site plans do not indicate the date of the topographic data. The existing conditions may be very different and new topographic data might need to be collected. 3 | P a g e Attachment A: Report from 2016 4 | P a g e COASTAL PROCESSES SPECIALIST WOODS HOLE SEA GRANT | CAPE COD COOPERATIVE EXTENSION gberman@whoi.edu | gberman@barnstablecounty.org 508-289-3046 | 193 Oyster Pond Road, MS #2, Woods Hole, MA 02543-1525 November 28, 2016 TO: Yarmouth Conservation Commission CC: FROM: Greg Berman, Coastal Processes Specialist (WHSG & CCCE) RE: Site visit to Crowell Beach, Yarmouth, MA – 11/03/2016 Background: Since the inception of the coastal processes position established within WHSG & CCCE, on- site and remote technical assistance on coastal processes has been and continues to be an on-going, effective technical information communication and dissemination tool. Technical assistance relating to coastal processes, shoreline change, erosion control alternatives, coastal landform delineation, potential effects of various human activities on coastal landforms, coastal floodplains, coastal hazards and hazard mitigation analyses, and dune restoration techniques provided in the field and remotely will continue to be provided on an as-needed basis. Site visits generally address site-specific coastal processes or coastal hazards related issues. Follow-up unbiased, written technical alternatives analyses are generally provided. Participants: Kelly Grant – Conservation Agent Greg Berman – Coastal Processes Specialist (WHSG & CCCE) Site Details: This report focuses on the property and land immediately adjacent to Crowell Beach, at the end of Crowell Road in Yarmouth (Figure 1). A NOI has been submitted to the Yarmouth Conservation Commission for 450 cubic yards (across a 31,000 ft2 area) of beach nourishment within the intertidal zone (MHW to MLW). This area is the fronting beach for parcel 72, and runs adjacent to a tidal creek that connects over 6 acres of wetlands to Lewis Bay. The owner of parcel 72 has permitted and recently dredged (summer 2016) the tidal creek in order to prevent inlet migration and the associated scour along the revetment protecting this property. A series of photographs was taken during a site visit on 11/03/2016. Photograph 1 was taken at the piling that was furthest to the south along the eastern side of the inlet. The boat storage racks can be seen to the west, as well as a high wrack line that was left from the astronomically high tide (aka king 5 | P a g e tide) two weeks previous. Photograph 2 shows the wooden slat fence along Parcel 72, as well as the inlet which has meandered significantly to the west since the last dredging in summer of 2016. Photograph 3 shows the thickly vegetated channel. Along the western edge of the channel it appears that sand has recently been transported on top of the marsh vegetation and into the channel (Photograph 3-zoom). The eastern side of Lewis Bay forms a small protected cove (Figure 1). In a typical cove, headlands characteristically erode with the sediment moving towards the center. In this case, tidal creek is coincidentally quite close to the center of the cove. It is the longshore (i.e., parallel to the beach) sediment transport over a long period (typically annually) that gives us a net transport to base coastal projects upon. More details on sediment transport can be found in Longshore Sediment Transport, Cape Cod, Massachusetts (Berman, 2011). Net transport was qualitatively measured at this site by examining multiple years of high quality aerial photography for impoundments of littoral drift in order to determine direction of longshore sediment transport. After the site visit, historic shoreline migration trends were examined through a time series of aerial photographs available from the MassCZM Massachusetts Ocean Resource Information System (MORIS – an online mapping tool), from the 1990s to 2014 (Figure 2). While the images may be from different times of the year (does not take into account seasonal beach changes) and tidal cycles (not all at low tide) some general trends are noticeable. The images from 2001, 2005, and 2008/2009 have fairly straight geometry for the tidal creek. On the other three images the inlet has meandered towards the northwest, with the tidal scour appearing to erode the fronting beach of Parcel 72. It is likely that this meander continues until a new inlet is cut (through dredging or naturally by new inlet forming) through the beach. As this new inlet is more hydraulically efficient than the one to the west, the newly formed small barrier island rapidly migrates landward and melds onto the eroded beach. The maximum fetch of this site is ~1.9 miles due west (Figure 3). The fetch from the northwest is much smaller (~0.25 miles) when compared to the potential from the southwest (0.5-1.4 miles), and therefore it is highly likely that during much of the year sediment would be transported from southeast to northwest in this area. This is supported by the inlet meander and sand bar bypassing (Figure 2). It should be noted that while longest fetch direction (from west) is relatively rare, it is roughly in line with the vegetated channel making it possible that direct cross shore (perpendicular) sediment transport might occur if wind occurs from this direction. This wind and wave direction that could transport existing or nourished beach sand into the channel and reduce the tidal flow. Recommendations/Considerations: • The site plans (dated 10/18/16) use topographic data from 07/11/16. The existing conditions on 11/03/16 are very different from 07/11/16 and new topographic data might need to be collected. It is possible that the nourishment material is proposed to fill the channel right now. This could push the channel further north and lead to erosion at Parcel 72, or the channel might erode the placed sediment much faster than anticipated. 6 | P a g e • There is already sand being transported north onto wetland vegetation and into the tidal creek. If wind and waves occur from the west there is a chance that some of the proposed nourishment may be transported to this area, potentially plugging up the channel and affecting over 6 acres of wetlands. • There is currently sediment coming from the southeast into the site. If you want to keep the inlet in a fixed position you’ll need to keep dredging the inlet to “reset the timer” on channel meander. If the channel could be dredged deeper or if a trap could be dredged on the southeast side of the channel it might prolong the time between dredging events. • This site would be best managed cooperatively. Dredging of the inlet could be performed in conjunction with beach nourishment. With a larger project, and higher beach, the channel might last longer in the desired location. Dredged sand is likely much cheaper and more compatible to the beach than sand from an upland site. • A sediment budget is the mass balance between inputs and outputs of sediment within a defined coastal environment. This is the type of information that might be helpful to determine the volume that needs to be bypassed annually (or if intervention can be prolonged to a longer timeframe) and placed to maintain the supply to all downdrift beaches. More information on sediment budgets is available at: http://coast.noaa.gov/archived/beachnourishment/html/geo/budgets.htm • The pilings would make an excellent location to take photographs from to document changes to the beach. Simply put the camera on top of the same post at the same angle each time and the images should provide valuable data about coastal change and the impacts of various projects at this site. 7 | P a g e Figure 1. Location of site. 8 | P a g e 2013/2014 2011/2012 2008/2009 2005 2001 1990s 2013/2014 2011/2012 2008/2009 2005 2001 1990s Figure 2. A series of aerial images downloaded from MORIS (CZM interactive webmap) of the site, with the date of acquisition indicated in red in the upper left corner of each image. 9 | P a g e Figure 3. Maximum fetch of this site is due west and indicated in red. Additional fetch measurements are provided in brown. 10 | P a g e The red arrow on the image to the right indicates the location and direction of the photograph at the bottom of this page in red, and the other photograph in the series is yellow. Note the background image is from 2013/2014 and may not represent current ground conditions. Photograph 1. Looking towards the beach access (white boat racks) from the furthest seaward piling east of the inlet. 11 | P a g e The red arrow on the image to the right indicates the location and direction of the photograph at the bottom of this page in red, and the other photograph in the series is yellow. Note the background image is from 2013/2014 and may not represent current ground conditions. Photograph 2. Looking towards the northwest. The channel has a significant meander despite recent dredging. 12 | P a g e The red arrow on the image to the right indicates the location and direction of the photograph at the bottom of this page in red, and the other photograph in the series is yellow. Note the background image is from 2013/2014 and may not represent current ground conditions. Photograph 3. The tidal creek is well vegetated north of the sandy beach. Some of the sand looks recently mobilized by either wind and/or water. 13 | P a g e Photograph 3-zoom. A zoomed in view of photograph 3 shoeing recently mobilized sediment.