Design of the
Montauk Sewer System
East Hampton’s engineering consultant, H2M, has recommended that the sewer system in Downtown Montauk be designed as a “gravity-fed” sewer system for the most part. That is the cheapest option. Sewer pipes in a gravity system have to be laid under the streets with a very precise downhill gradient, so that wastewater in the pipes flows on its own, and with the necessary “self-cleansing” velocity. This means an “open cut” of all ditches is required to ensure that the pipes have the proper downhill pitch.
The gravity-fed system is proposed to empty into a principal sewer main to be laid under South Elmwood Avenue, the street nearest to the ocean. The South Elmwood pipe will be a “low-pressure” sewer main, which will draw wastewater to the west, until it reaches a pumping station on the Montauk Highway at South Eagle Street, which is just west of the Kirk Park Beach parking area. The land on the west side of South Eagle is owned by the Town but is not dedicated as parkland, so it can be used for sewer facilities. These will include a so-called “wet well” or underground collection basin, a pumping station within a control building, and an emergency backup generator. These facilities will be pretty much right on Montauk Highway at the entrance to Downtown Montauk, enclosed within a security fence.
The Town will have to install 11,000 linear feet of sewer pipe in Downtown Montauk just for the gravity-fed portion of the sewer district. The “low pressure zone” part of the sewer system, along South Elmwood Avenue, will require another 3,700 linear feet of pipe. That’s a lot of excavated roadway (almost three miles). There will also be 40 sanitary manhole covers to be installed, just in the gravity-fed portion of the network. And all of this doesn’t include the sewer force main to be installed under the Montauk Point State Parkway (Rt. 27) shoulder to get from Downtown Montauk to the Montauk Recycling Center, nor the excavation of the access driveway through the Recycling Center.
For any cyclists wondering if the Town will fully repave these roads after installing the sewer pipes - the answer is “NO.” The H2M report states that its estimated costs are based only on strip repaving of the trenched areas - not curb-to-curb repaving of the whole street.
There are a couple of especially notable elements to the proposed Downtown Montauk sewer system. First, the main sewer collection main will run beneath South Elmwood Avenue, which some people think will be below sea level in a few decades. Second, the pump station and backup generator are proposed to be located in an obvious flood plain area, where a hurricane might breach the dunes and flood the pump building and generator. The design of the sewer system is intended to keep costs down and make things flow by gravity as much as possible. Also, the pump house and generator can’t be on parkland, which further limits the Town’s options. Nevertheless, under the present design of the sewer system the Town is clearly be proposing to put new critical infrastructure in areas endangered by flooding, erosion, and possible sea level rise.
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