1. A
supplier of water proposing to:
(a) Construct
a new facility for filtration and disinfection; or
(b) Make additions to or modify significantly
an existing facility for treatment,
must submit an engineering report to the Division or the
appropriate district board of health. The report must be approved by the
Division or the appropriate district board of health before the supplier begins
construction. The report must also describe how the facility will be designed
to ensure that it complies with this section and NAC 445A.531.
2. A new facility for
filtration and disinfection must:
(a) Be
designed to attain an average daily effluent turbidity goal of 0.2 units of
nephelometric turbidity when using conventional, direct, and diatomaceous earth
filtration plants.
(b) Be free of
structural and sanitary hazards.
(c) Provide for protection against
contamination by backflow.
(d)
Provide equipment for measuring and recording flow.
(e) Provide equipment for measuring and
recording the combined filter effluent turbidity.
(f) Be designed to mitigate the effects of
events such as earthquakes, fires, floods, freezing and sabotage that are
reasonably foreseeable.
(g) Provide
reasonable access for inspection, maintenance and monitoring of all unit
processes.
(h) Provide for a
coagulation process that includes rapid chemical mixing and is based on pilot
plant or laboratory scale or equivalent results that demonstrate effectiveness
of the coagulant chemicals over the full range of water quality conditions
expected.
(i) Provide for
filter-to-waste for each filter unit or addition of coagulant chemicals or
organic polymers to the water used for backwashing.
(j) Provide backwash rates and facilities for
surface or subsurface wash using air, water or a combination of these to clean
the filter.
(k) Provide treatment
for the removal of solids from filter backwash water if the water is recycled
into the treatment process. Recycled backwash water must be returned to the
headworks of the treatment plant.
(l) Make provision for facilities for
pretreatment in the design of direct filtration, slow sand filtration or
diatomaceous earth filtration plants.
(m) Provide equipment for disinfection that
is of proper size for the full range of expected conditions of flow and capable
of feeding accurately at all rates of flow.
(n) Provide for operation of the treatment
plant without frequent shutdowns and start-ups.
3. As used in this section, "filter-to-waste"
means a provision in the filtration process to allow the water that was
filtered first to be wasted or reclaimed.
Added to NAC by Bd. of
Health, eff. 11-29-90; A by Environmental Comm'n by R126-05, 10-31-2005;
R194-08, 10-27-2009
