Jun 11 2020
Periodic Nourishment 2017 - Stone Harbor
Dredge Texas working off of Stone Harbor
Townsends Inlet Seawall
Jul 30 2013
Project Index Map
2017 Periodic Nourishment - Avalon
Coastal Research Amphibious Buggy
The CRAB, or Coastal Research Amphibious Buggy, conducts surveys of the surf zone in Avalon during 2017 beachfill operations.
2019 Periodic Nourishment
Sep 11 2019
2017 Periodic Nourishment in Avalon
North Wildwood Seawall Construction
North Wildwood Seawall
N. Wildwood/Anglesea Seawall
Initial Construction - Avalon
The Townsends Inlet to Cape May Inlet Coastal Storm Risk Management Project was authorized by Congress in 1999. The project includes the construction of a dune and berm system with a 3-year nourishment cycle (pending available funding) and 2.2 miles of seawall along the Townsends Inlet frontage of Avalon and the Hereford Inlet frontage of North Wildwood. The design calls for a 150 foot berm (or beach) backed by a dune constructed to elevation +14.75 (North American Vertical Datum of 1988). The beachfill portion of the project was initially constructed in 2002. The Townsends Inlet seawall was completed in 2006. The Hereford Inlet seawall was constructed in 2 phases with the Phase 1 completed in 2007 and Phase 2 completed in 2010. The dune and beachfill project was renourished/repaired in 2011, 2013, 2017, and 2019. The Hereford Seawall was repaired in 2014 and 2020-2021.
The project is designed to reduce the risk of damages to infrastructure from coastal storm events.
The dune and beachfill portion of the Townsends Inlet to Cape May Inlet project was initially constructed in 2002 and has been subsequently renourished and repaired. The next scheduled periodic nourishment is scheduled for 2022 pending available funding. The Townsends Inlet seawall was completed in 2006. The Hereford Inlet seawall was constructed in 2 phases with the Phase 1 completed in 2007 and Phase 2 completed in 2010. Repair work along the Hereford Inlet (Anglesea) seawall began in 2020 and finished in 2021.
Initial construction of dune and beachfill
Construction of Townsends Inlet and Hereford Inlet seawalls
FCCE Emergency Repair
Periodic Nourishment (scheduled; pending funding)
In cooperation with the New Jersey Department of Environmental Protection (NJDEP) and the City of North Wildwood, the U.S. Army Corps of Engineers (USACE) awarded a contract to Agate Construction to repair damage along sections of the Hereford Inlet Seawall.
Erosion along the underwater edge of the wall caused portions of the wall to collapse. To fix the problem, Agate will install concrete block mattresses that extend into the channel along the bottom of the inlet. The mattresses will then be covered with more than 20,000 ton of stone. The mattresses are designed to fold into areas of erosion and prevent the erosion from migrating towards the wall. Prior to Labor Day, all construction work will be from barges in the inlet. Concrete mattress and stone will be loaded on the barges from Staging Area #1 (see construction map on below tab). Following Labor Day, construction will begin from land based operations adjacent to the wall.
Continued erosion along the seawall between when USACE designed the seawall repairs and actual construction resulted in additional failure along the seawall. To address this issue, USACE expanded the contract with Agate, within the original scope of work, to add an additional 21,000 square feet of Articulated Concrete Block (ACB) mattresses, 5,000 tons of stone fill and 400 tons of 2-ton cap stone.
The seawall was originally constructed in 2009 and provides coastal flood risk management for homes along the Hereford Inlet.
Safety of our workers and the public is our primary concern. Construction sites are full of hazards that workers are trained and outfitted to handle. Please help us keep you and our workers safe by following all caution signs, staying clear of heavy equipment and large vehicles, and not letting curiosity bring you inside our secured work area. Be aware of increased truck traffic, construction noise and other hazards that present themselves around the construction area. Your awareness and vigilance help us ensure ZERO accidents.
Structure and Vibration Monitoring
Construction activities such as moving large equipment and stone placement can cause the ground to shake. If the shaking or vibrations are large enough, they can cause damage to nearby structures. To avoid this, the Seawall Repair contract requires that the contractor monitor their activity in order to predict and prevent damages to structures as a result of their work. The contractor does this by strategically placing seismographs around the project site where large and/or heavy equipment are operating. The seismographs are placed to capture the highest peak particle velocity created by the construction activity and record continuously using threshold-type and fully automated seismographs. Because the magnitude of vibrations decrease as the distance from the source increases, monitors are not required in all buildings as alerts are set to trigger at thresholds below the damage limits at the monitored location.
An alert warning is given to the contractor and USACE personnel if any measured vibration exceeds 0.60 inches per second (IPS) or 80% of the allowable limits established by the U.S. Bureau of Mines (USBM RI 8507). If an alert is issued, all work will stop until remedial measures and/or modified construction procedures are identified.
It takes a substantial amount of vibration to cause damage to surface structures, underground structures, pipelines, sewers and water wells. Surface structures, underground facilities and wells are dynamic in nature and as such are subject to a variety of internal and external forces such as settlement, weather and changes in soil moisture, excavation, and frost levels.
The U.S. Bureau of Mines Report of Investigations 8507, “Structure Response and Damage Produced by Ground Vibration from Surface Mine Blasting (USBM RI 8507) reported the following findings:
Ground-borne vibration is not a phenomenon that most people experience every day. Human response to vibration in buildings is very complex. The degree of annoyance cannot always be explained by the magnitude of the vibration alone. In some cases, the complaints are associated with measured vibration that is lower than the perception threshold. Other phenomena such as ground-borne noise, rattling, visual effects such as movement of hanging objects, and time of day all play some role in the response of individuals.
USACE Philadelphia District
100 Penn Square E.
Philadelphia, PA 19107