Residuals Management - Public Water Systems - page 806

natural uranium, respectively. If no state or local standards are in place, the NRC
standards may be used as a guideline for surface water discharge. Some states and
local authorities have promulgated conservative limits of 10 percent of the NRC levels
under 10 CFR 20 for release of radionuclides into the environment. 1
Discharge into Sanitary Sewers State or local regulations that set limits for wastes
discharged to sewer systems will govern those discharges. The NRC limits the dis-
charge of wastes containing radioactive materials into sanitary sewers by licensees.
For NRC licensees, the monthly quantity of soluble radium-226, radium-228 and nat-
ural uranium, diluted by the average monthly quantity of total water treatment wastes
released into the sewer, should not exceed 600 pCi / L, 600 pCi / L, and 3,000 pCi / L,
respectively. Also, the gross quantity of all radioactive material combined, excluding
tritium and carbon-14, released by the facility into the sanitary sewer should not exceed
1 curie per year, according to the same NRC standards. These are put forth by EPA
in this context as standards that might be considered. 1
Well Disposal A drinking water treatment plant owner interested in disposing of
wastes containing radionuclides into an injection well should consult with the appro-
priate state agency first. State regulations may be more stringent than federal require-
ments and may ban such practices.
Regulation of water treatment plant wastes containing radionuclides depends on the
concentrations of radionuclides present and on the type of well. Shallow wells are
defined as those above or in an underground source of drinking water (USDW). Shal-
low injection of radioactive wastes is currently a banned practice.
Radioactive wastes are treated differently from nonradioactive wastes under appli-
cable Underground Injection Control (UIC) programs. Currently a waste is considered
radioactive if it contains concentrations of more than 60 pCi / L, or natural uranium of
more than 300 pCi / L.
Well disposal of radioactive waste below a USDW is currently considered a Class
V well injection and is under study by EPA as part of the Class V regulatory devel-
opment effort.
Other Options Other treatment or disposal options for a liquid waste containing
naturally occurring radionuclides include evaporation, sand drying or lagooning, chem-
ical precipitation of contaminants, and other solids separation techniques. Lagoons or
other impoundments should, at a minimum, be lined to prevent infiltration. Any evap-
oration unit should be designed and operated properly to ensure isolation of the waste
from the water table.
Solids and Sludge Disposal
Table 23-23 shows disposal guidance according to current EPA guidelines for landfill
disposal. In all cases, sludge concentrations are expressed in terms of dry weight.
Land Disposal EPA does not recommend the application, mixing, or otherwise
spreading of water treatment wastes that contain naturally occurring radionuclides onto
open land (i.e., farmland, pasture, orchard or forestry lands, construction sites, road-
beds, etc.).