| (a) This section applies to the storage of sludge after
processing but before final disposal or removal from the wastewater
treatment facility site.
(b) Sludge in liquid, dewatered, or dry form may be
stored at the wastewater treatment facility if the solids have been
stabilized in a treatment process.
(c) General Storage Requirements.
(1) A sludge storage facility must prevent nuisance
odor conditions and minimize vector attraction.
(2) A sludge storage facility must provide storage
of waste sludge separate from a biological treatment process.
(3) The design of a sludge storage facility must be
based on process design, sludge age, waste stream concentration, operational
hours, operational volume in tanks, decant or dewatering volumes and
characteristics, time frames needed for decanting or dewatering, and
volume needed for storage and sampling.
(4) The engineering report must include a solids management
plan that describes a method for managing the waste solids that will
maintain the design sludge age for a biological process.
(d) Storage of Solids - Not Dewatered.
(1) Aerobically Digested Solids.
(A) A storage facility may store aerobically digested
solids.
(B) A sludge storage basin must have diffused air or
mechanical mixing.
(C) A diffused air-mixing unit must provide a minimum
air capacity of 30 standard cubic feet per minute per 1,000 cubic
feet of volume.
(D) A mechanical surface aerator must have a minimum
of 1.0 horsepower per 1,000 cubic feet of volume.
(E) An earthen sludge storage basin must be lined in
accordance with §217.203(d) and (e) of this title (relating to
Design Criteria for Natural Treatment Units).
(2) Anaerobically Digested Solids. Anaerobically digested
solids must be stored in a covered basin with gas release valves and
gas control measures.
(e) Storage of Dewatered Solids.
(1) Dewatered solids must be stored in a steel or concrete
container, or in an open stockpile.
(2) Dewatered solids with a solids content of less
than 35% must not be stored for more than seven days. Dewatered solids
with a solids content of at least 35% but not more than 50% must not
be stored for more than 90 days.
(f) Open Stockpiles.
(1) An open stockpile must have an impervious pad underneath
the solids to prevent groundwater contamination.
(2) An open stockpile must have a system for collecting
stormwater runoff and returning it to the headworks of the wastewater
treatment facility.
(g) Dried Solids Storage.
(1) A storage facility may store dewatered solids with
a solids content of greater than or equal to 50% in a covered bin
or covered facility for a period of time that does not exceed two
years.
(2) An enclosed storage structure must be mechanically
ventilated with at least 20 complete air exchanges per hour and must
have an odor control system for the exhaust.
|
