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Type A Foundation/Cistern - Glencoe Mill Village Installation

Objectives:
1. Install prefabricated concrete tanks adapted to support a portion of the house addition above them.
2. Store rainwater in these tanks subsequently be used for irrigating
nearby garden areas.
3. Use as an earth retaining wall restraining three feet of soil backfill on the uphill side of the installation.
4. Compare material and installation costs to conventional foundation construction and water storage technology.

   

Location and jurisdictional approval

The first type A foundation/cistern installation to be completed in North Carolina. Construction completed by New Earth Home and Garden, licensed general contractor, in a National Registry of Historical Places location outside of Burlington, North Carolina.

   

Design and installation had to conform to Preservation North Carolina and City of Burlington Historical Review guidelines requiring the tanks to not be visible from any part of the site location and its surrounding area. In addition, this installation was inspected and approved by the City of Burlington Building Permit Department both before and after structural framing was completed.

Description

Type A cisterns differ from their counterparts in that they are made from newly adapted pre-cast concrete septic tanks. Standard tanks are delivered to the site and once placed on prepared surfaces, they are modified in the field.

New Earth Home and Garden performed the installation using two 750 gallon capacity rainwater tanks, each tank being retrofitted with additional reinforced concrete at specific load bearing points. No concrete footings were used to support these tanks. All building loads are being transferred via the tanks to a gravel support base beneath them. The gravel was placed on undisturbed soil having a minimum load bearing capacity of 2000 pounds per square foot.

 

Rainwater is directed into the tanks using existing and new roof areas for catchment surfaces. Stored rainwater can be distributed to the garden via a pump which is activated whenever the adjacent exterior hose bibb valve is opened. Overflow and drain line connections are gravity flowed about 60 feet downhill from the tanks.

Access for maintenance is provided above the tanks and in the crawl space between the tanks.

Costs

This amounts to $1.90 per stored gallon of rainwater, which is less than current market costs for installed buried water tank systems. No additional foundation pier walls or footings were required, thereby saving time and costs for conventional foundation related construction.

 

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