Page 214 - Water and Wastewater Engineering Design Principles and Practice

CHEMICAL HANDLING AND STORAGE 5-17

⎛ 1 ⎞ ⎛ 1 ⎞
3
⎟ ⎜
.
(4750 kg/d ) ⎜ ⎝ 24 h/d⎠ ⎝ 1 440 kg/m ⎠ ⎟ 014 m /h
,
3
,
3
where 1,440 kg/m is the density of ferric chloride from Appendix A. This is in the op-
3
4
erating range of 3 10 to 5 m /h.
d. Transfer piping
From Table 5-5 , select a 50 to 100 mm diameter schedule 80 PVC pipe.
e. The arrangement of the system is shown in Figure 5-4
.

5-7 DESIGNING FOR SAFETY AND HAZARDOUS CONDITIONS
Table 5-6 provides a general overview of safety requirements and protective measures for han-
dling chemicals. Many of these measures are to be implemented by the operators, but several
require design provisions. Material Safety Data Sheets (MSDS) provided by the manufacturer of
the chemical provide more detailed information on its safe handling. Another general reference
for chemical safety, exposure limits, and incompatibilities is NIOSH Pocket Guide to Chemical
Hazards (NIOSH, 2003).
The Emergency Planning and Community Right-to-Know Act (EPCRA), also known as
Title III of the Superfund Amendments and Reauthorization Act (SARA), requires facilities
with chemicals above the thresholds given in Table 5-7 to report this to the State Emergency
Response Commission (SERC) and coordinate with the appropriate Local Emergency Planning
Commission (LEPC). Construction of a new facility exceeding these amounts requires that the
owner notify the SERC and LEPC. Operating and maintenance manuals should address these
issues.
In many communities, chlorine gas is the most hazardous substance in substantial quan-
tity in the community. Not only is it a hazard because of potential accidental release from
delivery through application to the water supply, but it also is a security hazard. Although it
is more expensive, sodium hypochlorite (NaOCl) is being used to replace gaseous chlorine to
reduce the hazard that gaseous chlorine poses. Many water treatment plants are using alterna-
tive disinfectants, such as ultraviolet (UV) radiation and ozone, to reduce the need for large
amounts of chlorine. Wastewater treatment plants have implemented the use of UV for the
same reason.

5-8 OPERATION AND MAINTENANCE

The major issues in operation and maintenance are safety programs and training, preventive
maintenance, good housekeeping, and good record keeping.
Because the concentrated chemicals used in water and wastewater treatment are for the most
part harmful to human health, formal safety programs are essential. This includes periodic hands-
on training, provision of appropriate safety equipment in accessible locations, and provision of
personal protective equipment (PPE).