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Dune Road Beachfront

Project Details

Architect :    Steven C. Gaetano
Type :    New Construction
Services :    Civil Engineering
Surveyor :    David Fox
Builder :    Steven C. Gaetano
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Project Summary

This project featured construction of a 10 bedroom, oceanfront estate set on Dune Road in Quogue. Situated on 2 acres+/-, the residence capitalizes on views of both the Atlantic Ocean and Shinnecock Bay. With 128 feet of direct ocean frontage, this new construction 8,300 SF+/- estate includes and outdoor terrace space including a roof deck, and a north/south facing tennis court.

Engineering Challenges

Like most coastal sites, there were several Civil engineering challenges to overcome including low elevation, high groundwater and wetlands.
A dewatering plan and anti-buoyancy measures were required as the I/A septic tanks were to be installed into groundwater.
A pressurized shallow drain field was utilized as it is the most shallow of the leaching structures approved by SCDHS.
Additionally, Cultec chambers were utilized as a high groundwater stormwater retention/detention system.

Core Design Concepts

Low Elevation & High Groundwater

High ground water brings a few installation and design challenges.
The septic system must be designed to have a means of anti-buoyancy to ensure the septic unit will stay in place during and after installation. (2) Hydro Action AN-500C treatment systems were selected for this design. Being constructed of concrete with a weight of over 16,000 lbs., anti-buoyancy requirements were satisfied.

Shallow Leaching Field

Leaching structures must be designed with adequate separation to the highest expected ground water. In this case, a pressurized shallow drain field (PSD) was utilized as it is one of the most shallow leaching structures available.
Often pumps are utilized to overcome the the inability to design a gravity fed leaching system, especially in the case where the elevation is so low that mounding up is required.
What these systems lack in depth, they make up for in length and width which is often a challenge to fit on the site. 113 linear feet of Geomat 3900 was proposed to provide 1,100 gallons per day in infiltration in addition to reserving space for 50% expansion.

Shallow Stormwater Drainage

Due to the high groundwater elevation, traditional concrete drywells were not an option as they would not allow for the proper separation to groundwater. A shallow drainage chamber solution was proposed. This solution is installed in a bed of gravel, is extremely low profile and can support traffic bearing applications such as driveways.

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