Automatic Flushing Device Preserves Water Quality

Environmental Enhancement and Technologies of Naples, Florida, has introduced a Direct Discharge version of the Hydro-Guard automatic water distribution system-flushing device.

The new unit functions exactly like its predecessor except that water is discharged through a 2-inch PVC pipe allowing flushed water to be connected directly to the user's choice of discharge (i.e., culvert, storm sewer, sanitary sewer, etc.). Both Hydro-Guard units save water utilities money by eliminating the need to send distribution system crews out to manually flush poor quality water from water systems.

The Safe Drinking Water Act Amendments require water utilities to maintain a maximum chlorine residual at any point within their distribution system at no more than 4 mg/l. At the same time, a minimum chlorine residual of no less than 0.2 mg/l (free chlorine) or 0.6 mg/l (combined chlorine) must be maintained at all points in the system. These new regulations decrease the range of chlorine levels allowed in the system.

Problems associated with water quality degradation are particularly acute with dead-end or cul-de-sac lines and low-demand portions of water distribution systems. Oversized water mains required for fire protection and by land development codes often compound the problem.

The Hydro-Guard system is powered by a 9-volt lithium battery that will operate the unit for one year. Water mains can be flushed at any time of the day and for any duration desired. The water main flushing schedule is input to the unit's operating module using a hand-held programmer. The flushing operation schedule is based on a 7 or 14-day repeating cycle period with three input parameters: 1) days of operation during the cycle, 2) flush start time, and 3) flush finish time. The unit may flush up to 16 times per day if desired.

All Hydro-Guard units have a built-in water quality sampling port. By setting the system to flush prior to sampling, the samples will be representative of the water quality inside the main, thereby reducing the potential for false positive bacteriological results.

The units are constructed of non-corrosive and weather-resistant materials.

The direct discharge unit uses a 2-inch brass Wilkins Zurn 975XL RPZ valve for backflow prevention. Connection to the water distribution system is made through a standard 2-inch service connection. The unit weighs about 100 pounds and has overall dimensions of 25-inches by 36-inches and is 29-inches high. The base is buried 10-inches in the ground and the 17-inch cover is lockable to restrict unauthorized access.

To accommodate freezing climates, EE&T has developed a freeze protection accessory that allows water to run through the unit at low temperatures to keep it from freezing. As the outside air temperature drops below 40 degrees Fahrenheit, the freeze protection accessory opens a thermally controlled valve that allows up to 1 gallon of water per minute to flow through the unit. The warm water also maintains the temperature of the electronic controls.