HomeMy WebLinkAboutquestion response Letter_12.14.2022
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December 14, 2022
Ref: 15144.00
Yarmouth Conservation Commission
Yarmouth Town Hall
1146 Route 28
Yarmouth, MA 04096
Re: Great Island Road Resiliency Project
Dear Commissioners:
VHB is providing the following information in response to requests and questions raised at the December 1st, 2022,
Yarmouth Conservation Commission public hearing.
Offshore Dredging
The Commission asked why dredging was not being proposed as a nourishment source, as they had concerns
regarding the addition of more sediment into the system and its impact on local waterways.
By using an upland sediment source, the project avoids the alteration of additional wetland resource areas (Land
under Ocean) and minimizes potential for impacts to eel grass beds . Dredge projects can have negative effects on
benthic communities in the nearshore areas that would be avoided with the proposed option of upland sourcing of
the nourishment materials. Upland sourcing of sand achieves the project purpose without additional alteration of
Land under Ocean. The project proponent coordinated with CZM, DEP, DMF, NHESP during and after the State
Environmental Notification Form (ENF) process, and none of these agencies indicated concern that the use of
upland sources would be detrimental to shoals, sand bars, or navigation channels offshore of the project. The
agencies also requested that the proponent undertake a sediment transport study to model the nourishment
project.
An extensive coastal processes analysis, “Coastal Processes Analysis: Great Island, Yarmouth, Massachusetts”, dated
April 2022 and prepared by Sustainable Coastal Solutions, Inc., was performed to model the shoreline at the Great
Road beach and Fox Point. A determination of recent changes in the topography and bathymetry of the beach was
performed to see how sand moves on the beach and in the nearshore, particularly within the multiple bars that exist
offshore of the beach. The analysis indicated a dominant west-to -east littoral transport. Consistent with most
nearshore regions along the south facing shore of Cape Cod, a west-to -east longshore transport is observed as
accretion on the western (updrift) side of the groins and erosion on the eastern (downdrift) side. This would suggest
that sand eroding from the beach face of the western side of the project shoreline is moved east where some of this
material is deposited. The project was also reviewed and approved by the Yarmouth Waterways and Shellfish
Committee, who , after raising similar concerns agreed to the project as proposed.
Yarmouth Conservation Commission Ref: 15144.00 December 14, 2022 Page 2 Dune Vegetation
The Commission requested that additional species be planted along the back of the dune in order to increase
biodiversity. VHB previously worked with NHESP to create a planting plan appropriate for the piping plover habitat.
While vegetative species mix at time of planting may be dependent on local nursery stocks, some common coastal
dune species include beach plum (Prunus maritima); northern bayberry (Morella pensylvanica); seaside goldenrod
(Solidago sempervirons); beach heather (Hudsonia tomentosa); sweet fern (Comptonia peregrina); and sea lavender
(Limonium carolinianum or nashii). These can be used to increase the biodiversity on the back side of the dune,
while maintaining the dune seaward face and beach area plantings with dune grass, as proposed, and approved by
NHESP. The final planting list will be determined during the construction phase in coordination with NHESP, the
contractor, and the Commission based on availability of locally grown native stock sources.
Truck Trips
The Commission requested further information on the number of truck trips required to bring the upland sediment
on site.
As a contractor has not been procured yet for this project, the type and size of equipment has yet to be determined.
Given the scale of the project and assuming an average of 35 cubic yards per truck trip it is anticipated that the
number of truck trips would be numerous and would likely exceed 2,000. The number of truck trips are not
anticipated to have an effect on the wetland resources protected under the Wetlands Protection Act, but access
points from the road will be carefully selected to minimize any secondary impacts. The most appropriate locations
for access would be areas where the road is closest the beach front in areas with little or no vegetation. The project
will be undertaken with as few access points as possible. Once a contractor is selected, a construction access plan
will be provided to the commission. No trucks will be allowed to access the beach by any other means beyond the
identified location to prevent any impacts.
Groin Removal
The Commission inquired whether the removal of the groins was considered as part of the project.
Removal of the groins was considered and dismissed early in the project development. Many of these groins have
nearby eel grass beds that would likely be disrupted by their removal. Further, the presence of these groins are
anticipated to help the nourishment project be maintained for longer. VHB coordinated with various agencies,
including CZM DEP, MA DMF and NHESP over the methodology of the beach nourishment project. During this
coordination, agencies indicated that nourishing around and on top of the groins was appropriate and did not
require the removal of these structures. It was decided to leave the groins in place to avoid any additional
unnecessary alterations.
Additionally, the groins significantly extend the service life of the proposed beach nourishment template. Without
these structures, beach nourishment at a higher frequency would be required along with the associated
construction resource area impacts.
Yarmouth Conservation Commission Ref: 15144.00 December 14, 2022 Page 3
Sincerely,
VHB
Meredith Avery
Managing Director - MA Environmental
cc: Great Island Homeowners’ Association