SECTION 252:626-13-4. Lagoons

(a)   General. Lagoons used for the treatment of WTP waste shall be designed, permitted and constructed in accordance with OAC 252:656-11. In addition, lagoon designs shall include the following:

(1)   two or more lagoon cells that provide for a minimum residual storage time of six (6) months per lagoon cell,

(2)   design lagoons for the periodic removal of residuals as required in OAC 252:631-3-19,

(3)   a minimum of 3 feet of freeboard,

(4)   adjustable decanting device,

(5)   effluent sampling point (if lagoon is permitted to discharge),

(6)   a pond gauge, to measure the level of residuals in the lagoon.

(b)   Surface evaporation lagoons (total retention).

(1)   Size lagoons to store both the expected wastewater and residuals produced.

(2)   Provide sufficient surface area to evaporate the wastewater generated.

(3)   Base evaporation rates on the annual average pan evaporation minus the 90^th percentile annual rainfall.

(c)   Surface water treatment wastewater handling. Design for:

(1)   at least 4-hours settling time prior to recycling,

(2)   wastewater to be returned to a point prior to the point of primary coagulant addition,

(3)   wastewater to be returned at an instantaneous rate of 10 percent or less of the raw water entering the plant. Total flow shall not exceed the WTP maximum design flow rate, and

(4)   when wastewater is to be discharged, a plant outfall must be provided that is designed and constructed in accordance with OAC 252:656-9-3.

(d)   Sealing of lagoons. Water treatment plants utilizing conventional, microfiltration or softening treatment may seal the lagoons with any approvable material listed in OAC 252:656. For all other types of treatment, the lagoons shall have a synthetic liner that meets the requirements of OAC 252:656.

(e)   Evaporation ponds. The waste from ion exchange plants, demineralization plants, etc., that cannot flow to a sanitary sewer or meet discharge permit requirements without cost prohibitive treatment may flow to evaporation ponds meeting the requirements of OAC 252:619, 252:621 and 252:656.

[Source: Added at 18 Ok Reg 1612, eff 6-1-01; Amended at 25 Ok Reg 2304, eff 7-11-08; Amended at 29 Ok Reg 1035, eff 7-1-12; Amended at 33 Ok Reg 1472, eff 9-15-16]