Separation Chamber. The large particle siliconized
sodium bicarbonate is partially soluble in water; however, its
density is so close to that of water it should stay in
suspension with the slightest agitation. Grit and sludge from
other sources should accumulate in tanks associated with the
wastewater stream and a method for its removal should be
included in the tank design. Training wastewater from the fire
training structure should be piped to a separation chamber to
remove the propane. For details refer to par. 3.2.9 and
Appendix A, Figure A-15.
Pretreatment. Fire training wastewater should be
collected in an equalization tank sized to hold 125 percent of
the largest one day's effluent. This should allow various
firefighting agent concentrations to mix and dilute each other.
It should also allow a homogeneous batch of wastewater to be
monitored and then discharged to the sanitary sewer system at a
controlled rate. There should be two equal size equalization
tanks so that one can be discharging while the second is
receiving. During maintenance periods the active tank can
discharge at night. Each of the equalization tanks should have
draft marks in increments sufficient for operators to estimate
tank contents to the nearest 1900 L.
tanks should be designed for flexibility of use. Tanks should
overflow to each other. Each tank should have provisions for
mechanical agitation and sludge removal. The agitation should
be a high volume low head pumped recirculation system with a
operator can manually adjust between submerged or open
discharge. The open discharge would afford some aeration.
Sludge handling provisions may consist of a sump or trough to
which the grit can be hosed for removal by shovel and bucket.
The sump should have a drain piped directly to the exterior of
the tank for future addition of a pumped system if it becomes
practical. Provide permanent personnel access to the bottom of
tanks and a standpipe, SP, so tanks can be hosed down with a 40
mm fire hose.
b) Consideration should be given to the option of
using a covered reservoir. The trade-offs are the cost of