An automatic flushing device is available that can be programmed to flush water lines without supervision, helping solve disinfectant residual and water quality problems without the need for manual flushing programs.
Safe Drinking Water Act Amendments will require that water utilities reduce the maximum chlorine residual at any point within their distribution system to no more than 4 mg/l while at the same time maintaining a minimum chlorine residual at all points in the system of no less than 0.2 mg/l (free chlorine) or 0.6 mg/l (combined chlorine).
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. Fire protection and land development codes often require oversized water mains which compounds the problem.
Hydro-GuardTM, an automatic water distribution system flushing device, was designed to improve water quality with minimal operating costs. Used by operators to maintain distribution system water quality, they help reduce bacterial presence and control biofilm by flushing out stale water with low disinfectant residuals. The flushers are manufactured by Environmental Enhancement & Technologies USA Inc.
To install the system, an operator connects the device to a service connection and programs its operation for a planned flushing schedule. A battery-powered programmable controller opens and closes a solenoid-operated valve at preset times. Batteries have a one-year life. The device has a built-in sample port and an optional manual flushing port. The programmer is multilingual
The flusher is made with noncorrosive and weather-resistant materials, and weighs approximately 46 pounds. It contains three main components. The Controls Module houses the 14-day 36 event battery operated controller, 9-volt lithium battery and built-in sample port (5 in. H x 8.5 in. dia.). A hand-held programmer plugs into the module through a RJ-11 jack to download the flushing schedule. The Mechanical Module houses the discharge riser, flow/energy dissipater chamber, flow discharge chute and internal fastening devices (19 in. H x 6 in. dia.). The buried Base Module houses a 2 in. nylon glass reinforced solenoid operated valve, sample tube connection, fittings and external splash plate (19 in. H x top-18 in. dia. X bottom-24 in. dia.).
Cleaning and then routinely flushing a problem pipeline can help improve chlorine residuals levels and discourage the regrowth of biofilm. A successful program consists of regular partial flushing of problem water mains. This can take the form of a release of 100 gpm for 15 minutes on dead-end lines on a daily or less frequent basis.
Operational Benefits
The flushing system can improve delivered water quality, as well as reduce color, turbidity, taste, odor, biofilm and red water. Water flushed regularly also achieves regulatory compliance related to coliform and heterotrophic plate counts (HPC).
Operational Benefits
Collier County, Fla., used the flushing system on a dead-end street, raising the chlorine residual in that stretch of pipe to more than 3 mg/l. To obtain this reading, the line at first had to be flushed for 4 minutes at a rate of approximately 150 gpm every night. The length of time for flushing was then reduced to obtain a target average of 2 mg/l chlorine residual maintenance level.
