Okla. Admin. Code § 252:656-19-6
For systems that land apply biosolids, design on-site temporary sludge storage facilities to hold the sludge volume produced during a three-month period. Biosolids shall not be stored for greater than six (6) months without prior written approval from the DEQ and in no case longer than one (1) year. For dewatered sludge, provide concrete or equivalent surfaced facilities with appropriate drainage systems to store treated sludge. Drainage systems must return supernatant or other liquids to the headworks of the treatment system. Sludge storage must accommodate daily sludge production volumes and function as an operational buffer for unit outage and adverse weather conditions. Designs utilizing increased sludge age in the activated sludge system as a means of storage are not acceptable. On-site storage of dewatered high pH stabilized sludge shall be limited to 30 days. Provisions for rapid retreatment or disposal of dewatered sludge stored on-site shall also be made in case of sludge pH decay.
Okla. Admin. Code § 252:656-19-6