Post-Florence Renourishment Project - Phase II (2020)
2/17/2020 – AWESOME PROGRESS, 2nd SUBMERGED PIPELINE SET. We had great “dredging weather” this past weekend with no mechanical issues, thus enabling; (a) seamless, repeated rotations between the borrow site to dredge and sailing to the beach to pump out, and (b) an opportunity to set the 2nd submerged pipeline (“subline”) that is situated at “Station 992+50” at Smugglers Cove. Great Lakes Dredge & Dock (GLLD) has multiple subline assemblies here on site and will continue “leapfrogging” the sublines to the west. GLLD should be finished progressing west off the 1st subline landing in a day or two and will transition to the 2nd subline landing, pumping sand back eastward (SEE 2/17/2020 PROGRESS MAP). Some nice examples of dune construction below.
Photos (February 17, 2020) - Dune Construction Before a Pump-Out Cycle
|New "Baby" Dune Freshly Contoured|
|Buried Stairs = dune tie in at +12 Feet||Bulldozers Contouring Dune - no poles/stakes; all GPS|
2/14/2020 – PIPE FLIPPED AT 1st SUBMERGED PIPELINE LANDING (HEADING WEST NOW). Great Lakes Dredge & Dock (GLDD) completed going east (or past the Circle) yesterday afternoon, and has subsequently “flipped the pipe” at the 1st submerged pipeline landing and are now progressing westward (see 2/14/2020 Progress Map). GLDD plans to tug and install the 2nd submerged pipeline over the weekend, and pumping operations should start on this 2nd landing sometime next week once they finish the western leg off the 1st landing. Dredging operations have pretty much been uninterrupted since they first started on Saturday (2/8/2020), and we’re hoping for the same this upcoming week.
2/10/2020 (8:00 am) – NICE PROGRESS. As expected, we’re experiencing some strong productivity a little over a day and a half into the project (~1,600 linear feet) as the sand is being pumped eastward from the first subline landing (see 2/10/20 update map and photos below). The second "subline" (again see map) is scheduled to be set later today at Station "992+50".
Photos (February 10, 2020) - Just After A Pump-Out
|Photo 2||Photo 4|
2/8/2020 – PROJECT START! The seas have subsided subsequent to the storm we experienced over the course of the past couple of days, and the dredge Liberty Island departed from the Morehead City Harbor/Port at roughly 2 pm to the borrow site, dredged the first true load of sand, sailed to the pump-out station, and started delivering sand to Atlantic Beach at approximately 4:30 pm (see photos below). Nourishment will progress eastward (i.e., “towards the Circle”) from the subline landing position near “Station 1066+00” in Ocean Ridge (SEE MAP).
We should see strong productivity for this first week or two – the distance between the borrow source and pump-out station will be shortest now as the project in a macroscopic sense moves westward and further away from the borrow source. A light load of sand was delivered to the beach as part of mandatory testing/inspections on Thursday before the storm came through, but again the project started in earnest today.
Photos (February 8, 2020)
|Dune Feature Contoured|
|Slurry of Sand/Water||Yellow Steel Ready to Work|
2/5/2020 – LIBERTY ISLAND IS HERE; COULD START TOMORROW OR SATURDAY.
We're basically all set to begin dredging and pumping sand on the beach.
(A) The cube/pickup-line has been affixed to the submerged pipeline that lands on the beach (see 1/29/2020 for further explanation), and is ready to serve as a conduit for sand to be delivered from the hopper dredge.
(B) Much of the land-based beach pipe has been delivered and towed to the first subline landing area in Atlantic Beach (possibly 10,000 feet of pipe in total will ultimately be mobilized to the site).
(C) The dredge Liberty Island arrived on Monday (2/3/2020), and is undergoing a minor, minor type of repair while moored to one of berths at the Morehead City Harbor Port.
Dredge inspections are tentatively scheduled for tomorrow morning (2/6/2020) and the project can start in earnest shortly thereafter. However the weather/sea state could be problematic, and in that case, we are planning for a Saturday (2/8/2020) start date.
Photos (January 29, 2020)
|Subline Landing 2||Close up of bell joint (will attach to subline)|
|Staging of Pipe at Iron Steamer||Staging on the Beach|
1/22/20 - IRON STEAMER WILL SERVE AS STAGING AREA, STILL LOOKING AT 1st WEEK of FEBRUARY. Not much change to the anticipated schedule mentioned in the 1/8/20 update below. Ideally the first submerged pipeline (subline) will be towed offshore and placed in position early next week (see “1st Pipeline Landing” MAP). The dredge Liberty Island should arrive shortly thereafter and if the weather cooperates with the placement of the subline and everything else, we could begin nourishment the first week of February working eastward (i.e., “towards the Circle”) from the 1st subline landing. Also note staging of the land-based pipeline sections, heavy equipment, etc. will now be at the Iron Steamer Access in Pine Knoll Shores.
1/8/20 – PRE-CONSTRUCTION MEETING, LOGISTICAL NOTES, 1st WEEK of FEBRUARY. The project sponsors (Carteret County, Atlantic Beach, Pine Knoll Shores, & Emerald Isle), Engineers (Moffatt & Nichol), and the dredging contractor (Great Lakes Dredge & Dock) had a pre-construction meeting earlier today that essentially “kicks-off” the project. Great Lakes Dredge & Dock (GLDD) plans to mobilize land- and water-based pipe, heavy equipment, personnel, etc. starting next week and dredging/pumping is scheduled to begin in the first week of February. An area at the Circle (Atlantic Beach) will serve as the main staging area for the land-based pipe.
The dredge Liberty Island will arrive on-site first and will generally progress and “leapfrog” east to west from Atlantic Beach and continue into Pine Knoll Shores. At some point in mid-March the larger hopper dredge, the Ellis Island will essentially relieve the Liberty Island of her duties and continue “leapfrogging” down the beach to finish the Phase II effort in West Emerald Isle before the April 30th environmental window closes for the sea turtle nesting season and other biological resources.
As described below, subsequent to completing a “cut” and filling the hopper, the dredge will travel and discharge (pump) sand via a buoyed pick-up pipeline located offshore that transitions to the pre-construction dry beach via a submerged pipeline assembly (or "subline"). A secondary “elbow’ connection is used to transport material in one direction (east), then the other direction (west) along the beach to complete approximately 1 - 2 mile sections as lengths of pipe are added and subsequently broken down. The pick-up line/subline/elbow assemblies are subsequently transited (leapfrogged) down the beach until the nourishment reaches have been filled. The following maps have been updated depicting the approximate locations where the sublines will land in succession for West Atlantic Beach, Pine Knoll Shores, Salter Path, and West Emerald Isle.
HOW TO INTERPRET THE PROGRESS MAPS
for The Post Florence Renourishment Project (Phase II)
Phase II of the Post Florence Renourishment Project will utilize 1,995,000 cubic yards (cy) of sand obtained from the Offshore Dredged Material Disposal Site (ODMDS) associated with Morehead City Federal Navigation Project. West Emerald Isle (EI), Salter Path (IB), Pine Knoll Shores (PKS), and West Atlantic Beach will receive 345,000 cy, 140,000 cy, 990,000 cy, and 520,000 cy, respectively along 9.5 miles of shorelines in four discrete reaches depicted in the Project Construction Map above. As a mental picture, a conventional dump truck holds roughly 12 cubic yards of wet sand. The project is scheduled to be conducted between January 1 to April 30, 2020 and therefore within the construction window established to limit impacts to biological resources. The dredging contract has been awarded to Great Lakes Dredge & Dock and the ocean-certified, self-contained hopper dredges Liberty Island and Ellis Island will be employed for the project - similar to the Phase I effort in 2019.
Hopper dredges utilize dragheads affixed to trailing-arm suction pipes mounted on both sides of the vessel (port and starboard). The dragheads loosen the sand on the bottom off the seafloor and deliver the material to the vessel’s “belly” via the suction arms. Subsequent to completing a “cut” and filling the hopper, the dredge will travel and discharge (pump) sand via a buoyed pipeline located offshore that extends to the pre-construction dry beach. A secondary “T-valve” discharge pipe is used to transport material in one direction (east or west), then the other along the beach to complete approximately 1 - 2 mile sections as lengths of pipe are added and subsequently broken down. The buoyed pipeline and T-valve assembly is subsequently transited down the beach until the nourishment reaches have been filled. Dredged sand will be bulldozed into general construction specifications for subsequent grading into final contours, possibly tilled, and opened for recreational use. The dredges Liberty Island has a maximum capacity of 6,540 cy and the Ellis Island 14,800 cy under optimal conditions.
Project engineers use “stations” positioned along the beach to monitor construction progress and to verify in-place volumes of sand pumped on the beach by dredging contractors. The progress maps above provide detailed views of the Post Florence Renourishment Project (Phase II) reaches to be completed in 2020 with the location/identification of the station numbers and the location of buoyed pipelines. The shaded areas in red represent the completed portions of the project and will be updated on a weekly basis (at least) throughout construction.
The station numbers included in the progress maps conveniently correspond to thousands of linear feet along the beach. For instance, the distance between station “825+00” (Iron Steamer Access) and “896+00” (Memorial Park Access) on the Reach 9 - Pine Knoll Shores Area of Detail graphic above is 7,100 feet. If you visit the beaches of Bogue Banks this winter, you may see wood or metal stakes at the base of the dunes that will identify these station numbers as such.
PROJECT PLANNING & IMPLEMENTATION
The geographical extents and basic geometries of the Phase II, Post Florence Renourishment Project are included in the accompanying "Key Documents" on top of this webpage, and the project was formulated based upon design and cash-flow considerations. Every municipality along Bogue Banks has or is scheduled to receive sand between the Phase I and Phase II projects while maximizing the local and State funding we have in hand to address all of the more critically eroded areas along the Island, coupled with any FEMA funding that has been received to date. Weeks Marine and Great Lakes Dredge & Dock furnished bids for the Phase II effort with the former (Great Lakes) providing the lowest awardable bid price. Great Lakes was also our Phase I contractor. Phase III of the Post-Florence Renourishment Project is tentatively scheduled for winter 2020-2021 and will encompass Central and Western Emerald Isle.
In cross-section going from the top of the dune seaward, the beachfill will be contoured by; (1) tying into the existing, eroded frontal dune at +12 or +13 feet NAVD 88 and maintaining that top dune elevation at vary lengths as one progresses seaward, (2) the slope of the newly constructed frontal dune will be graded on a 5:1 slope to the elevation of +6 feet NAVD 88, (3) the beach berm (flat part of the beach) will be extended from that point seaward at +6 feet NAVD 88 at varying lengths, and (4) the slope of the fill from the berm crest out to sea will be on a 20:1 slope. The newly created dune crest and dune slope will be planted (vegetated) with Sea Oats as part of the contract (see typical cross-section above).
The borrow source for this nourishment effort is the Offshore Dredged Material Disposal Site (ODMDS) associated with Morehead City Federal Navigation Project. This dump site is essentially a repository for dredged material historically extracted from the Outer Harbor reach of the navigation channel and based upon experiences with a 2004 and 2007 Section 933 Project that utilized channel material for beach nourishment and 2004, 2007, 2013. and 2019 post hurricane projects that actually utilized the ODMDS; we expect the sand quality to be excellent. This also makes intuitive sense, because for the most part, the shoal material that enters the navigation channel at Beaufort Inlet is sand that has traveled from adjacent beaches. Construction, or deepening material that resides in the ODMDS should be avoided. To this effect the firm of Moffatt & Nichol, who has been retained by the Bogue Banks communities as the engineering consultant for the Post-Florence Renourishment Project, has performed additional sediment sampling and analyses in the ODMDS to hone the areas of beach quality sand.