DREDGING SUMMIT & EXPO ’18 PROCEEDINGS

DREDGING THE COMPLEX – CREATING CAPACITY, BENEFICIAL USE THROUGH BEACH NOURISHMENT, AND ENHANCING THE GREATER GOOD OF THE MANASQUAN INLET AREA

W.S. Douglas1 , W. Henderson2, M. Marano3, T.W. Chen4 and S. Flanigan5

ABSTRACT The Manasquan Inlet is one of ’s busiest recreational and commercial maritime complexes. This busy seaport is facilitated by a Federal channel (2.3 nautical miles (4.26 km)), 13 State channels (5.9 nautical miles (10.93 km)), and numerous local channels. Maintenance of this system is typically performed by hydraulic cutterhead pipeline dredge with placement in one of two confined disposal facilities (CDF’s) or on public beaches (coarse-grained material only). We will discuss the recently completed maintenance dredging of the Manasquan River Complex. This state-sponsored project provided direct relief for over fifty waterside businesses, over 180 private residences, multiple recreational access and bathing areas, and a critical United States Coast Guard (USCG) Search and Rescue Station.

As part of the recovery effort following Superstorm Sandy, NJDOT performed a system wide condition survey of State channels. This survey determined that the Manasquan complex would require dredging of approximately 390,000 CY (298,180 CM) of sediment to return it to a state of good repair. Of this, over 41,500 CY (31,700 CM) of material could be directly attributed to the storm. While ample capacity for coarse grained material was available on several public beach areas, the two confined disposal areas did not have available capacity for the 60 percent of the material that was determined to be fine grained.

It was determined that only the Gull Island CDF might be modified to accept dredged material. Gull Island CDF is a 9.36 acre (3.79 Ha.) facility on a 22 acre (8.90 Ha.) island, just west of the Inlet. Project timing precluded expanding the facility footprint and the existing berms were very steep and underlain by soft, organic soils, so raising the dike crest elevation was not a viable solution. Construction of a geotextile reinforced stockpile using the existing CDF material was proposed. The stockpile was designed to an elevation nearly fifteen feet (4.5 M) higher than the confining berms to create the needed capacity. A subsurface monitoring program was also proposed to detect any deep-seated movement of the existing berms that could eventually lead to failure.

Project improvements include placing sand on one of New Jersey’s most popular bathing beaches consistent with a USACE beach fill program; the addition of Cooks Creek channel, home to the USCG Search and Rescue Station and charter and commercial fishing enterprises; and a mutually beneficial solution for Monmouth County by providing sand for a County beach.

1 Dredging Program Manager, New Jersey Department of Transportation Office of Maritime Resources, 1035 Parkway Avenue, Trenton, New Jersey 08625 USA T: 609-530-4770, Email [email protected]. 2 Resident Engineer, New Jersey Department of Transportation Office of Maritime Resources, 1035 Parkway Avenue, Trenton, New Jersey 08625 USA T: 609-530-4770, Email [email protected]. 3 Engineer of Record, WSP USA, Inc. 2000 Lenox Drive, Lawrenceville, New Jersey 08648 USA T: 609-512-3516, Email [email protected]. 4 Geotechnical Engineer, WSP USA, Inc. 2000 Lenox Drive, Lawrenceville, New Jersey 08648 USA T: 609-512- 3444, Email [email protected]. 5 Design Engineer, Gahagan & Bryant Associates, 9008 – O Yellow Brick Road, Baltimore, Maryland, 21237-5608 USA T: 410-682-5595, Email [email protected]

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Details of the construction and dredging sequence, monitoring program, and challenges met during the project will be discussed.

Keywords: Dredged material management, maintenance dredging, beneficial use, beach replenishment, confined disposal facility

INTRODUCTION

Figure 1. Project Location Map – Manasquan Inlet – Ocean and Monmouth Counties, New Jersey

The Manasquan River forms the border between Ocean and Monmouth Counties on the coast of central New Jersey, emptying into the Atlantic at the Manasquan Inlet; one of several Federally-maintained coastal inlets in the State and the initiation point for the NJ . Figure 1 shows the general project area located on the central New Jersey coastline. The Manasquan River and Inlet is one of New Jersey’s busiest recreational and commercial maritime complexes, home to 16 marinas, 50 water dependent commercial businesses, a commercial fishing fleet, a US Coast Guard search and rescue station, several heavily used bathing beaches and numerous ocean and riverside residences. Access is facilitated by a Federal channel (2.3 nautical miles 4.26 km)), 13 State channels (5.9 nautical miles (10.93 km)), and numerous local channels, lagoons and berths. Boaters can not only access the ocean via the Inlet, but they can also access via the Intracoastal Waterway which continues south through the Manasquan Canal, located approximately 2.7 miles (4.35 km) west of the Inlet. Dredging of one or more portions of the system is required nearly yearly, with material being placed on beaches or in one of two confined disposal facilities (CDFs) located at opposite ends of the 5.6 mile (9.01 km) long system. The larger (and more important) of the two CDFs is on Gull Island, a 22 acre (8.90 Ha.) island located in the middle of the River just inside the Inlet. In addition

423 DREDGING SUMMIT & EXPO ’18 PROCEEDINGS to being home to the 9.36 acre (3.79 Ha.) CDF, it is also a bird refuge, providing critical nesting and foraging habitat for a number of protected species including Osprey, American Oystercatcher and Least Tern.

As part of the recovery effort following Superstorm Sandy, NJDOT performed a system-wide condition survey of State channels. This survey determined that the Manasquan complex would require dredging of approximately 390,000 CY (298,180 CM) of sediment to return it to a state of good repair (authorized depth). Of this, over 41,500 CY (31,700 CM) of material could be directly attributed to the storm. While ample capacity for coarse-grained material was available on several public beach areas, neither of the two confined disposal areas had any appreciable capacity remaining. This necessitated a prioritization in order to provide as much navigational relief as possible while minimizing cost and maximizing our use of the available capacity. Since the CDF at the far western end of the complex was the smallest, and held in private ownership, the focus naturally fell to the larger publicly-owned Gull Island CDF. DESIGN PARAMETERS AND PROJECT CONSTRAINTS State Channels Using the prioritization matrix shown as Table 1, below, five channels were initially selected to be dredged within the project area: Lower Manasquan River Channel, Crabtown Creek Channel, Kings Bridge Channel, Wills Hole Thorofare Channel, and Wills Hole West Channel.

Table 1. Prioritization matrix for the State channels proposed to be dredged in the Manasquan River Complex, Ocean and Monmouth Counties, New Jersey.

Channel Shoaling Usage Economic Logistical Volume Dredge Final Status Value Constraints - CY (CM) Material Rank Distance to the Composition CDF ft. (M) Upper Severe High Moderate 26,250 (8,000) 177,285 >75% fine Low Manasquan (135,500) River Lower Moderate High Moderate 18,000 (5,490) 35,694 Coarse with High Manasquan (27,290) some fine River Sawmill Severe High Low 21,750 (6,630) 42,706 >75% fine Low Creek (32,650) Glimmer Moderate Low Low Historic Bridge 10,508 >75% fine Low Glass (8,030) Watsons Moderate Moderate Low Historic Bridge 14,340 >75% fine Low Creek (11,000) Shermans Moderate Low Low Historic Bridge 5,138 >75% fine Low Creek (3,930) Crabtown Severe Moderate Low 4,750 (1,450) 10,763 >75% fine High Creek (8,230) Kings Moderate Low Low 3,250 (990) 8,681 >75% fine Mod Bridge (6,640) Channel Wills Hole Moderate Low High 2,750 (840) 45,899 Coarse with High Thorofare (35,100) some fine Wills Hole Moderate Low Low 7,500 (2,290) 12,827 >75% fine Mod West (9,800) Cooks Creek Minor Moderate High 2,750 (840) 1,676 >75% fine Low (1,280)

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Manasquan Severe Low Low 5,750 (1,750) 2,040 >75% fine Low Yacht Club (1,560) Clarkes Minor Moderate Moderate 9,250 (2,820) 3,372 >75% fine Low Landing (2,580)

Gull Island Confined Disposal Facility Following an initial survey, it was determined that the Gull Island CDF had insufficient capacity for the channels targeted for priority dredging (approximately 26,000 CY (19,900 CM) of available air capacity in the pre-existing condition of the Gull Island CDF). Several reconstruction alternatives were investigated: excavating and raising the confining berms, expanding the existing CDF footprint, and reconstructing and restoring an existing bulkhead and area of historic fill on the east end of the island. Limited access for an in-depth geotechnical investigation, lack of as- built drawings and steep existing slopes (between 1.5 and 2:1, even steeper in some isolated areas) eliminated the alternative of raising the existing berms. Expanding the CDF footprint and/or restoring the existing bulkhead area would require a lengthy permitting and alternatives analysis process. Unfortunately, environmental windows for dredging in coastal NJ are very restrictive (typically 6-9 months), therefore an extensive permitting process could delay the project start for a year or more. Given the critical needs identified for this important resource, delays of this magnitude were not acceptable. From the engineering perspective, several issues were quickly identified. First, it had been previously determined that a very soft, organic soil layer was present about 10 ft. (3.0M) below the ground surface. Second, there was evidence that the steep berm walls had been prone to sloughing and erosion losses into the surrounding waterways. Given the close proximity of some of the steepest berm walls to the critical commercial facilities on Wills Hole Thorofare, it was decided that a full evaluation and engineering analysis of the site would be required in order to properly restore or design an expansion alternative. Again, timing was critical, therefore the CDF expansion and restoration options were eliminated.

The preferred alternative featured construction of a geotextile reinforced stockpile within the confines of the existing CDF by using the previously dredged material present. The stockpile was designed to an elevation nearly fifteen feet (4.5 M) higher than the confining berms to create the needed capacity. The existing berm had a controlling low elevation between 30 ft. (9.1 M) and 31 ft. (9.4 M) NAVD’88. The borrow material was to come from within the CDF; existing ground was at about elevation 25 ft. (7.6 M) and the bottom of excavation was proposed to be elevation 10 ft. (3.0 M). The shape of the borrow pit was designed to have a 20 ft.-25 ft. (6.1-7.6 M) buffer area between the top of the 3:1 excavation slope and the toes of any existing dikes and/or the proposed toe of stockpile.

Figure 2. Plan view of the proposed construction within the Gull Island CDF

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The stockpile was designed to have 3:1 side slopes and a top elevation of 45 ft. (13.7 M) NAVD’88. Three geogrid layers spaced at 1 ft. (0.3 M) intervals starting from the existing ground levels were also proposed to enhance stability. Figure 2 shows the proposed excavation and stockpile construction limits in plan view. This CDF design provided an approximate air capacity in the Gull Island CDF of 77,500 CY (59,200 CM) to a freeboard elevation of 29 ft. (8.8 M) NAVD’88. The amount of fine-grained dredge material that needed to be placed into the CDF had an in-situ volume of approximately 58,000 CY (44,300 CM). Given this dredging need and the preferred alternative, capacity (both available and working capacity) was going to be a serious concern throughout construction. Figure 3 below shows a typical section taken longitudinally through Gull Island to show the existing and proposed conditions, as well as the predicted stacking of the coarse-grained material in the dredge slurry.

The material in the various channels was sampled as per NJDEP Office of Dredging and Sediment Technology protocol. Samples were analyzed for contaminants and grain-size. Contamination levels were below regulatory concern and the grain-size ranged from 39% to >90% sand. Since the material greater than 90% sand could be placed on the Manasquan Beach, only the material less than 90% sand had to be placed in the CDF. Based on these results and in an effort to preserve capacity, two additional design elements were introduced. The inflow pipeline was proposed to be routed into the CDF at a specific location and be placed on top of the stockpile. This would allow the sand in the dredge slurry to stack up at an inflow point that is theoretically higher than the controlling low dike elevation. If a substantial sand cone formed, the plan was to advance the inflow point to the west, further into the CDF, with the intention of stacking the sand component as much as possible. To protect against erosion and enhance stability, a turf reinforcement mat was proposed along the side of the stockpile where inflow was proposed. Additionally, a preferred order of work was listed on the plans. The channels were ordered from highest to lowest percentage of sand content, again, in an effort to preserve as much capacity within the CDF as possible.

Figure 3. Cross-sectional view of the excavation and reinforced stockpile design within the Gull Island CDF

Subsurface Monitoring Program A subsurface monitoring program was also proposed to detect any deep-seated movement of the existing berms that could eventually lead to failure. Inclinometers were proposed at 5 locations; 3 between the stockpile and the interior berm toes and 2 between the top of the excavated slope and the interior toes (See Figures 4 and 5). The frequency of the readings varied from daily to monthly, determined by the active construction of the CDF and stockpile, periods of active dredging, and any abnormal events such heavy rains or storm events.

The only way to collect subsurface data during the operation of the CDF is through the monitoring of these inclinometers. Their results can be influenced by many factors such as weather/temperature conditions, operation of the reading unit and how the raw data is processed. Accumulative displacement compared to the original zero reading (cumulative) and the first reading after the session zero reading (incremental) are both considered when evaluating any movement of the embankment. At of the conclusion of dredging in September 2017, the maximum accumulative and incremental displacements observed were approximately 1.1 and 0.6 inches (2.79 and 1.52 cm) respectively and these movements occurred near the ground surface. These readings were considered acceptable values for this project.

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Table 2 shows the summary of the maximum displacement and Figure 6 shows the time curve at the depth of maximum displacement occur of each location.

I-5 I-3

I-2 I-1 I-4

Figure 4. Inclinometer subsurface monitoring locations Figure 5. Inclinometer construction detail

Daily field observations of erosion, tension cracks in the berms, seepage rates and ground integrity near the inclinometer, were to be considered when evaluating the failure potential and the validity of the inclinometer readings. Joint readings by engineers and inspectors from independent parties involved in this project were frequently arranged to provide a comprehensive embankment safety evaluation in order for the dredging to move forward.

Table 2. Summary of Ground Movement from Inclinometers

Maximum Maximum Inclinometer Cumulative At Depth Incremental No. Displacement^ in. ft. (M) Displacement# in. (cm) (cm) I-1 1.10 (2.79) 0.61 (1.55) 2.3 (0.7) I-2 0.72 (1.83) 0.57 (1.45) 2.3 (0.7) I-3 0.66 (1.68) 0.64 (1.63) 2.2 (0.67) I-4 0.29 (0.74) 0.11 (0.28) 30.2 (9.2) I-5 0.47 (1.19) 0.47 (1.19) 2.3 (0.7) ^cumulative displacement compared to initial “zero” readings # incremental displacement since May 11, 2016 reading

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Figure 6. Time curve of ground movement from inclinometers

Beach Replenishment The Borough of Manasquan was a strong supporter of the project and was eager to receive free, beach-quality sand on their most popular bathing beach. The Borough initially suggested that the Contractor should simply pump the sand into a large stockpile and allow the borough to transport and grade it at their discretion. However, the United States Army Corps of Engineers New York District has been replenishing New Jersey beaches in earnest since SuperStorm Sandy. The USACE had a current contract to replenish beaches from Belmar, NJ to the Manasquan Inlet using the template shown in Figure 7. Needless to say, the proposed beach template for our project matched the USACE beach template. As long as the State agreed to match the USACE proposed beach template, they had an almost unlimited amount of placement capacity for dredge material that met the 90% or greater sand content requirement. Unfortunately, we were only able to place about 58,000 CY (44,300 CM) through bathing beach replenishment.

Figure 7. Manasquan bathing beach placement template compatible with USACE beach nourishment project from Belmar, NJ to the Manasquan Inlet.

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CONSTRUCTION CHALLENGES 2016 Gull Island CDF Construction After the project was awarded and the Contractor mobilized, excavation and stockpile construction within the Gull Island CDF began. NJDOT-style earthwork standards were specified in the contract documents. They include:

· No greater than 6” (0.15 M) lifts of material after compaction to 90% maximum density. · Determine maximum density according to AASHTO T 99 Method C. · Submit laboratory results 72 hours prior to start of construction for the maximum density determination for Resident Engineer (RE) approval. · RE will determine the compacted density using a Nuclear Density Gauge, taking 5 random samples for each subject lift, if any individual measurement is less than 90%, compaction must continue and/or corrective actions taken. · Geotextile materials must meet minimum strength requirements and each roll of material delivered to the site must be certified by the manufacturer. · Geotextile strength tests must also be performed and certified by a third-party laboratory. · Working drawing of panel layout and overlapping seams with the correct orientation of the strong and weaker directions must be approved by the design team before geotextile installation (geotextile shown in Figure 8 - right).

During the period of excavation and stockpile construction, the daily construction schedule could be adjusted based on the results from the subsurface monitoring program (inclinometer casing shown in Figure 8 - left). The State reserved the right to halt or slow down construction activities if excessive ground movement or potential failure was identified. The completed Gull Island CDF is shown from the air in Figure 9.

Figure 8. Geogrid reinforced stockpile construction. Note inclinometer in the foreground at left.

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Figure 9. Completed Gull Island CDF reconstruction. Aerial image credit: www.JerseyShoreDrone.com

Prior to the completion of the stockpile construction, the environmental agencies requested a change from the original design scheme of placing the dredge inflow pipe atop the stockpile. Their request of placing the inflow pipe through the stockpile was granted by the NJDOT Office of Maritime Resources (OMR) in the spirit of negotiation. Two of the species of concern on the island, Least Tern and American Oystercatcher, prefer the newly-created habitat at the top of the stockpile. In exchange for this design compromise, the agencies agreed to some leniency with regards to the environmental timing restrictions associated with the use of the Gull Island CDF. A condition of the permit required that a presence/absence survey for the species of concern be conducted prior to construction, and, if a presence was found, then construction activities would be restricted between April 1 and September 15th of any given year. The compromise allowed construction activities during the timing restrictions, as long as any nesting birds were not disturbed. While Least Terns were not observed during the project, American Oystercatchers did utilize the beach areas near the CDF for nesting. A professional biologist observed the birds carefully, and in consultation with NJDEP wildlife officials, it was determined that the birds were not affected by the work on the CDF.

Manasquan Bathing Beach Replenishment Instead of constructing training dikes, the Contractor excavated a basin upland of the High Tide Line (HTL) and recovered the coarse-grained material as it stacked up in the basin into adjacent stockpiles. The sand was then transported and graded within the permitted beach placement area. The Borough of Manasquan assisted operations using beach rakes to collect and dispose of dredged debris, larger shells, roots, ropes, pieces of pilings, etc. The town was very pleased with the final beach configuration once the beach placement operation was complete. You can see from the aerial photos in Figure 10 where the Manasquan bathing beach was the recipient of a beneficial re-use of coarse-grained dredge material.

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Figure 10. Before and after aerial view of Manasquan bathing beach. Aerial image credit: www.JerseyShoreDrone.com

Placement of Fine-Grained Material from the Lower Manasquan River After the dredging of the coarse-grained material from Wills Hole Thorofare and the easterly portion of the Lower Manasquan River Channel was completed, dredging operations continued in a westerly direction proceeding into finer-grained shoals in the Lower Manasquan. Pipeline was broken down and mobilized from the Manasquan bathing beach and re-mobilized to in-flow into the Gull Island CDF. The fine-grained material was dredged from Lower Manasquan River Channel during the last weeks of 2016. Environmental restrictions prohibited in-water work past the end of the calendar year. After the dredging was complete and the CDF was filled with dredged slurry, CDF inspections revealed excessive seepage at the toe of the southerly dike (shown in Figure 11). The seepage was noted and the CDF dikes closely monitored. The day following a winter storm, the daily CDF inspection identified a localized sloughing of the slope in the same area where the seepage was evident (shown in Figure 12). It was no surprise to the design team that the sloughing occurred on the steepest of the exterior slopes, greater than 1.5:1!

To further complicate matters, this localized sloughing happened to be located at the most visible and sensitive area of the project; directly adjacent to the commercial fisheries, public park, canoe launch, and dock and dine restaurant along Wills Hole Thorofare.

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Figure 11. Southerly berm of Gull Island CDF at low tide after inflow. Note the seepage paths in the center of the photo.

Figure 12. Localized sloughing of the southerly berm of Gull Island CDF.

CONSTRUCTION CHALLENGES 2017 Change of Plan No. 1 - Gull Island CDF Repairs At the suggestion of the design team, the State directed the Contractor to draw down the water in the CDF as quickly and safely as possible. Using the weir box and a mechanical pump the Gull Island CDF was safely dewatered. The dikes were inspected and stability monitored (via the 5 inclinometers) daily from when inflow commenced until a week after the CDF was safely dewatered. Then the daily dike inspections continued, but the stability checks were performed weekly.

While the initial response was being performed, a repair design was devised (as shown in the Typical Section of Figure 13). The design solution was two-fold; stabilize the exterior slope with high performance turf reinforcement mat (TRM) and minimize the seepage forces by installing a geomembrane on the interior of the CDF.

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Figure 13. Typical Section of the proposed repairs to the Gull Island CDF. High performance turf reinforcement mat on the exterior and geomembrane on the interior.

The exterior slopes were cleared, compacted and regraded to a slope no greater than 1.5H:1V. A top anchor trench was excavated, lined with TRM, mechanically anchored and then backfilled to provide sliding resistance as the TRM roll was installed down the newly reconstructed slope. The TRM was anchored with 18 in. (0.45 M) long pins every 1 ft. (0.3 M) on center and 9 ft. (2.7 M) long mechanical anchors every 3 ft. (0.9 M) on center. The mechanical anchors were comprised of stainless steel cables with a shovel-like shoe on the end to provide pull-out resistance when tensioned (anchor ends appear as green discs in Figure 14). Once the TRM was anchored into the slope, a toe anchor trench was installed using same procedures as the top.

Figure 14. Completed installation of the high performance turf reinforcement matting. Note the spacing of the in-slope anchors.

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The proposed geomembrane installation was similar in some aspects; the material came in rolls and had a top anchor trench, but very different in others; no mechanical anchors and the panels needed to be seamed together (see Figure 15 – left). The geomembrane acted as an impermeable barrier against the interior CDF slopes. The design intention was to direct any seepage forces towards the floor of the CDF and, thereby not through the confining dikes. The geomembrane was held in place during seaming and installation by strings of sand bags (see Figure 15 – right). These sandbags simply provided a passive restraint to resist any windblown uplifting forces.

Figure 15. Seaming operations during installation and final configuration of the geomembrane on the interior of the Gull Island CDF. Monmouth County “Dog” Beach Placement and Sand Recovery While the CDF repairs were being performed, the OMR was working other placement and operational alternatives to preserve as much capacity in the Gull Island CDF as possible. Manasquan Borough and Monmouth County were so pleased with the results on the Manasquan bathing beach that an additional beach placement site was made available; a County-owned park on the northerly bank of the Manasquan River within the project limits. The beach allows pet owners to bring their animals to the beach to enjoy the water, thus the “Dog” beach. Since this placement site was not classified as a bathing beach, dredge material greater than 70% sand was permitted to be placed there. The beach had sustained considerable erosion over time and was in need of replenishment. Sediment in Wills Hole Thorofare had been previously shown to contain approximately 72.3 % sand. The hatched area in Figure 16 indicates the permitted area for beach nourishment at the “Dog” beach.

Figure 16. NJDEP Acceptable Use Determination allowing fill of the Monmouth County “Dog” Beach

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Additional capacity in the CDF was obtained by recovering as much coarse grained material as possible from the dewatered material close to the inflow pipe and placing it on the top of the stockpile (shown in Figure 17).

Figure 17. Mechanical sand recovery and placement on top of the stockpile within the Gull Island CDF

Change of Plan No. 2 – Cook’s Creek and United States Coast Guard Facility When some local stakeholders realized that a maintenance dredging project was coming to the area, the OMR received requests for dredging relief and/or use of the available capacity in the Gull Island CDF. Cook’s Creek channel has a permitted design depth of -14 ft. (-4.3 M) MLW, but there wasn’t significant shoaling identified in the navigation channel during the priority assessment survey. It wasn’t until after the project started that the NJDOT OMR received word of shoaling in the channel and problems with the berth areas along the creek. Typically, the State will allow adjacent berth owners to approach the State’s Contractor for additional dredging work, if there is available capacity and only after the Contractor has completed the work agreed upon in the State’s contract. The OMR reached out to the adjacent channel berth owners to facilitate their dredging, but only the United States Coast Guard Search and Rescue Station on Cooks Creek, known as “The Point”, was able to obtain permits and get funding into place to seize this short window of dredging opportunity. Working with the USCG, the amount of channel dredging was reduced to match the desired berth depths of -12 ft. (-3.6 M) MLW to match the additional CDF capacity need of 9,260 CY (7,080 CM). Careful forecasting of capacity needs for the remaining work along with the mechanical sand recovery process and the permitting of placement at the Monmouth County “Dog” beach made it possible to accommodate the additional work on Cooks Creek. The sand recovery activities within the CDF moved approximately 10,000 CY (7,650 CM) to the top of the stockpile and the State was able to pump approximately 5,000 CY (3,820 CM) to the “Dog” beach. The State’s and design team’s ability to be flexible and innovative were essential to the successful completion of this portion of the contract. As you can see in Figure 18, Cooks Creek may not be very large, however its economic impact and essential services to the Manasquan Inlet and surrounding Atlantic Ocean region are substantial and, at times, life- saving.

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Figure 18. Cook’s Creek dredging stakeholders

SUMMARY / NEXT STEPS By September of 2017, dredging was completed on the Manasquan complex. About 2.96 nautical miles (5.48 km) of channel was restored to full navigability through the successful dredging of 122,710 cubic yards (93,820 CM), and much needed relief was provided to the communities that depend on the river for their livelihoods. Two heavily used public beaches received 48,860 CY (37,360 CM) of sand to further the recreational opportunities offered there. Despite many challenges, no environmental issues were encountered during the project and the confining berms remained standing. The Gull Island CDF is slowly dewatering, and it is time to look to the future. While beach placement will continue to be a viable option for coarse grained material, it is incumbent on the State to find capacity for the remaining 255,000 CY (194,960 CM) of fine grained material in the system, as well as new material that will surely be depositing in the channels. The most obvious solution would be to increase the size of the CDFs. Sensitive coastal wetland and beach habitat will likely prevent the State from using this option. Raising the confining berms is equally impossible. NJDOT and their consulting team are currently evaluating ways to accelerate the dewatering of Gull Island including methods of crust management and the installation of wick drains. While consolidation is unlikely to provide much in the way of additional capacity, this will allow for the more efficient characterization of the dewatered materials so that a permit for excavation and beneficial use of the almost 400,000 CY (305,820 CM) of dredged material stored there can be explored.

CITATION Douglas, W.S. Henderson, W., Marano, M., Chen, T.W., Flanigan, S., “Dredging the Manasquan River Complex – Creating Capacity, Beneficial Re-use Through Beach Nourishment and Enhancing the Greater Good of the Manasquan Inlet Area” Proceedings of the Western Dredging Association Dredging Summit & Expo ‘18, Norfolk, VA, USA, June 25 – 28, 2018.

ACKNOWLEDGEMENTS

The authors wish to acknowledge the outstanding contributions of the staff of the Office of Maritime Resources, NJDOT, WSP USA Inc., and Gahagan and Bryant Associates, and the NJDEP Office of Dredging and Sediment Technology for the many years of hard work without which the efforts presented here would not have been possible.

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