Blynman Bridge in Gloucester, MA is a high traffic area, for both cars and boats. The Department of Transportation was wanting to build a structure just above the retaining wall near the bridge. However, upon digging down for the foundation of the structure, they found large voids in the soil caused by the tide rising and falling, gradually eroding away the soils. These voids extended underneath the existing retaining wall, leaving it at high risk of sinking and/or failing.
Rather than replace the wall entirely, which would be a large scale project to first block off the ocean waters, and then pour a new wall, we suggested using our PolyLEVEL product to fill the voids. This solution would save the DoT money, time, and a lot of hassle. The challenge was to install the PolyLEVEL while fighting the tide waters, ensuring the foam product would have enough time to settle into the voids, expand, and solidify completely.
Working in the early mornings to beat the tide, our crews first inserted piping into the crevices, cracks, and voids. The PolyLEVEL foam material would be sprayed into these pipes, reaching deep into the earth to fill the voids which were mostly out of sight on the canal side of the retaining wall. A snake camera helped locate the voids.
Once the piping was in place, the foam was sprayed in and filled up the voids surrounding and under the wall. On the other side of the wall, opposite the water, some piping was used, but the voids were also much more visible and easy to access. Applying the foam here was not as much of a hassle.
With the PolyLEVEL foam all in place, the rising and falling tide waters were not able to flow under the wall as strongly as before. Waves are now unable to crash into the soils under the canal wall stones, and so the soil is no longer eroding away leaving behind voids.
The retaining wall system on this canal is now much stronger and no longer at risk of settling. The durable foam, which replaced the eroding soil, will not deteriorate in the salt water or wash away, and so the voids under the wall should not return. And although the water table is still high in this area and present in the soil, the water can no longer erode away the soils.