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BEACH HAVEN MARLIN & TUNA CLUB
Contracting Agent:
Beach Haven Marlin & Tuna Club
Project Location:
Beach Haven, NJ
Project Highlights:
The Beach Haven Marlin and Tuna Club noticed that their concrete patio deck was cracking and was sloping in the direction of the nearby inlet to the bay. The club also discovered a large (several feet in all dimensions) void under the slab inside the clubhouse in the vicinity of a recently replaced bar. Ground Penetrating Radar (GPR) was used to help identify the cause of cracks and sinking in the patio deck, to search for possible footings along the edge of the patio that may be supporting the columns for the awning over the deck, and to search for possible voids directly underneath the slab of the clubhouse.
Initial scanning was performed with a GSSI SIR-3000 GPR system with a 400 MHz antenna. Scanning was done in an X-Y grid pattern (approximately two feet on center) across the patio deck to search for any subsurface anomalies such as voids or water infiltration which might have been causing the ground to settle. A similar approach was used to scan inside the club to search for voids under the concrete. A 1.5GHz antenna was then used to scan around the perimeter of the awning’s support columns to search for any evidence of footings.
The radar images seemed to indicate areas of high water content and/or voiding starting at approximately three feet below the surface of the slab down to roughly seven feet. The bulk of the problem was located on the east side. No voids could be found under the slab of the clubhouse and the soil appeared to be very consistent. No footings could be seen with radar in the areas surrounding the support columns for the awning. The radar showed the slab to be an average of 9” thick with one mat of rebar approximately in the center.
Satellite image of the area.
Photo of the slab. The questionable area is past the orange line.
Illustration showing the section of the slab supported by questionable soil.
Radar image of the slab. X direction is distance, Y is depth. The bold black & white areas represent the saturated soil and possible voids.
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