The new drainage system is comprised of two main elements, a collection system and a stormwater well. A network of catch basins and connective infiltration trenches installed in the lower driveway will collect the stormdrain runoff. The surface of the lower driveway will be regraded to direct rainwater to the new catch basins. The catch basins are connected by perforated 18-inch pipes that are surrounded by six feet of rock and wrapped in a special fabric. The runoff, once collected in the catch basins, will travel into these pipes. The water will first pass through the perforations in the pipes, then through the rock and filtration fabric and ultimately into the surrounding ground. This insures that the water returned to the aquifer has been purified. When the lower driveway is saturated and unable to accept any more water, the excess will then travel through the network to the well.

The collection system is comprised of three new catch basins, the trench drain in front of the garage and the north and south catch basins located at the west end of the north and south decks by the street. Two basins were installed just north and south of the garage entrance. The garage trench drain empties into the basin that is located below the car wash stand. These two basins are connected to the new third basin at the west end of the lower driveway and the new well.

Our engineer, Brian DiGiralmo, designed a system that provides for several eventualities. A new pipe connects the north and south basins to the system in the lower driveway. Because the new system was designed to primarily address the lower driveway flooding, this connection is plugged, creating two independent systems. The runoff from the north and south decks will not be added to the runoff collected in the lower driveway. This relieves the well from having to dispose of the net rainfall that collects over entire premises. To accomplish its intended mission, it only needs to dispense with the overflow from the lower driveway. If, however, we find that any part of our system becomes overwhelmed for any reason, we can simply remove the plug to alleviate the problem, thereby avoiding additional future construction expenses. We were able to implement this system-wide safety net at no additional cost.

The well was excavated to a depth of 161 feet. After reaching 144 feet we finally attained a layer of hard rock and coral that provides appropriate access to the ocean. From 144 feet to 160 feet we have a geological shelf through which our well will always maintain a water table commensurate with that of the Atlantic Ocean. Because of our proximity to the Ocean, the system couldn’t depend on water having to travel up or down pipes. To offset the problem of the high water table, we installed a level system that is essentially a network of French drains connected to a well that will transfer its contents to the ocean. Because of the electrical outages that plague waterfront communities during severe weather, the system requires no appliances (such as pumps) that would cease to function during a power blackout.

The company that built the collection system, Atlantis Construction, has never before worked in such a tight area without closing it from start to finish. Because this construction is usually performed when a building is first erected, a litany of unexpected challenges had to be addressed on the fly. Despite these obstacles, the construction will be completed a week earlier than the three weeks anticipated. As expected, we had to close the garage for one full day, two half days and for several short intermittent periods during which equipment had to be repositioned. At the end of each work day, a road was built to provide overnight access to and from the garage. Thank you for your patience during this inconvenient procedure.