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Dunes CDD Water Supply and Treatment Primer

Things You Should Know About Your Drinking Water


The Dunes Community Development District (DCDD) owns and operates a 0.72 million gallon per day (MGD) water treatment plant that began service in August 2007. Provisions were made during the design and construction of this facility to double its capacity to meet future demand. Construction has begun to expand the plant to 1.44 MGD which should be completed in May 2015. When placed into operation, this project will continue to provide a safe, reliable, sustainable supply of drinking water for the community well into the future.

The Dunes CDD’s water supply comes from a groundwater source known as the Floridan Aquifer. The Floridan Aquifer is one of the major groundwater sources in the country and underlies all of Florida, southern Georgia, and parts of Alabama and South Carolina. This underground reservoir is made up primarily of sand and limestone layers. The Floridan Aquifer in this part of the state adjacent to the Atlantic coast is a highly mineralized, brackish water supply containing significant quantities of salt, hence the term brackish, and calcium and to a lesser extent magnesium and iron as well as the dissolved gases carbon dioxide and hydrogen sulfide.

Water is withdrawn from three Floridan Aquifer wells approximately 300 ft deep and is treated by a Reverse Osmosis (RO) treatment process. The RO treatment process removes salt and minerals from the water. After RO treatment, the water is aerated to remove dissolved gases carbon dioxide and hydrogen sulfide that are present in the groundwater but are not removed in the RO process. Chlorine in the form of sodium hypochlorite (commonly known as bleach) is used for disinfection purposes and to maintain a chlorine residual in the water distribution system.

RO water can be aggressive to plumbing systems if some form of post-membrane treatment is not included in the process. However, the Dunes CDD RO water plant adds an orthophosphate corrosion inhibitor post-membrane treatment to protect pipes and fittings in the distribution system as well as household plumbing. The pH of the water is adjusted using sodium hydroxide. Minerals, in the form of calcium chloride, and alkalinity, in the form of bicarbonate, are added to produce a stabilized product water. The purpose of these post treatment measures are to reduce the potential for corrosion of distribution piping and household plumbing.

Most hot water heaters are protected from corrosion with the installation of anodic protection. A sacrificial anode is provided to protect the hot water heater from corrosion. The anode rod in the tank of the hot water heater should be replaced if it has deteriorated to protect the hot water heater from corrosion as part of routine maintenance. Other routine maintenance of a hot water heater includes draining the tank to remove any sludge or sediment that may have deposited over time. The pressure relief valve should be tested to make sure it is working. This routine maintenance can extend the life of a hot water heater. Stray current corrosion can occur if the homes electrical system is grounded to the metallic pipes in the home plumbing system. Often the ground is made at the hot water heater inlet pipe if it is a metallic pipe. It may behoove those customers with their electrical system grounded to metallic pipes to explore other approved grounding options with a licensed electrical contractor and follow all local building codes and National Electric Code when making any changes to the grounding of their electrical system.

Some of our customers have installed water softeners. The Dunes CDD water is still considered “soft” even after post treatment processes which includes mineral addition. The Dunes CDD drinking water has an approximate total hardness of 45 parts per million (ppm) or 2.6 grains per gallon and calcium hardness of 35 ppm or 2.0 grains per gallon. Water softeners are unnecessary and will remove the minerals added in the post treatment process, producing extremely soft water that can be aggressive to home plumbing systems.

Invitation to Bid


Repair of Hammock Dunes Bridge

Scope of Services:

The project consists of providing repair and rehabilitation improvements to the Hammock Dunes Bridge (Palm Coast Parkway over Intracoastal Waterway, Bridge No. 734071) to the following components:     CLICK HERE for further instructions.


Please be advised that addendum number 1 has been issued.    READ MORE

Please follow the FTA link for addendum number 1 documents.    FTA LINK

Bid Opening

A bid opening was held on Friday, December 5, 2014 at 3:00pm at our Administrative Offices.  Click on  BID SUMMARY to view.

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Dunes CDD
101 Jungle Hut Road
Palm Coast, FL 32137

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