Enclosure VS PreCast Concrete Vault - First Cost Comparison

Utility contractors are noticing that water jurisdictions across the US are changing their standard details to include the above-ground installation of RPZ valves. Because RPZs provide the best protection for the water supply, Water Authority Officials are modifying their standard backflow preventer details to eliminate the use of single checks and double checks in order to provide the greatest level of protection for their drinking water. If you are in a territory that traditionally allows the installation of single checks or double checks in under-ground vaults, then you may be wondering about the difference between the precast concrete vault price and an above-ground enclosure price. Here are the basics:

Underground Utility VaultWorker operating a crane at a construction site.jpeg

Today’s standard utility vault installation has become a turn-key process. Waterworks distributors and concrete precasters generally provide a precast concrete vault which includes a double check or double detector check backflow preventer with all the required connections and spool pieces provided for one price. This is designed to make the purchasing and installation process easier for the utility contractor. The contractor must prepare the installation site, dig the hole for the vault to be dropped in by a boom truck, connect the spool pieces to the water line and backfill the area. The primary costs involved are (1) Preassembled Vault (2) Boom Truck, (3) Backhoe, (4) Labor.

Above-Ground Enclosure

When installing an RPZ in an above-ground enclosure, the process requires a concrete pad to support and secure the enclosure, the water line brought above ground and attached to the double check or RPZ backflow preventer, assembly of the enclosure, and running an electrical line for the heater. The primary costs involved are (1) RPZ and enclosure, (2) Concrete Pad, (3) Electrical, (4) Labor.

Your Price May Vary - Above-Ground Costs Lessbackflow_preventer_enclosure_on_top_of_vault.jpg

There are many variables to consider when analyzing the costs involved in these types of installations. Costs can vary on each aspect of the installation process depending on your location in the country. Rock excavation in locations like Middle Tennessee can require more cost to open the larger hole for the vault.

In order to compare the installation costs of vaults vs. enclosures, we reviewed multiple data points with water works distributors from various regions across the US. Looking at all material and labor costs we found an RPZ in a heated enclosure is generally 10%-15% less than a preassembled vault with a double check or double detector check. So, if you’re a municipal contractor in a territory requiring you to install RPZs for greater protection of the water supply, do not be discouraged, your installation costs are probably going to decrease. If you are a civil engineer wondering if the RPZ and enclosure will cost your owner more money, now you know it will likely cost less.

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