SAN DIEGO COUNTY AIR POLLUTION CONTROL DISTRICT

RULE 361.54 - SLUDGE SAMPLING
(Rev. Effective 3/27/90)

(a) As an alternative means for demonstrating compliance with Rule 361.52(b), an owner or operator may use Method 105 of Appendix B to 40 CFR Part 61 and the procedures specified in this rule.

(1) A sludge test shall be conducted within 90 days of the effective date of these regulations in the case of an existing source or a new source which has an initial startup date preceding the effective date; or

(2) A sludge test shall be conducted within 90 days of startup in the case of a new source which did not have an initial startup date preceding the effective date.

(b) The Control Officer shall be notified at least 30 days prior to a sludge sampling test, so that he may at his option observe the test.

(c) Sludge shall be sampled according to Subsection (c)(1) of this rule, sludge charging rate for the plant shall be determined according to Subsection (c)(2) of this rule, and the sludge analysis shall be performed according to Subsection (c)(3) of this rule.

(1) The sludge shall be sampled after dewatering and before incineration or drying, at a location that provides a representative sample of the sludge that is charged to the incinerator or dryer. Eight consecutive grab samples shall be obtained at intervals of between 45 and 60 minutes and thoroughly mixed into one sample. Each of the eight grab samples shall have a volume of at least 200 ml but not more than 400 ml. A total of three composite samples shall be obtained within an operating period of 24 hours. When the 24-hour operating period is not continuous, the total sampling period shall not exceed 72 hours after the first grab sample is obtained. Samples shall not be exposed to any condition that may result in mercury contamination or loss.

(2) The maximum 24-hour period sludge incineration or drying rate shall be determined by use of a flow rate measurement device that can measure the mass rate of sludge charged to the incinerator or dryer with an accuracy of ±5 percent over its operating range. Other methods of measuring sludge mass charging rates may be used if they have received prior approval by the Control Officer.

(3) The handling, preparation, and analysis of sludge samples shall be accomplished according to Method 105 in Appendix B to 40 CFR Part 61.

(d) The mercury emissions shall be determined by use of the following equation:

EHg = 1 x 10-3 cQ

where

EHg = Mercury emissions, g/day

c = Mercury concentration of sludge on a dry solids basis, µ/g (ppm)

Q = Sludge charging rate, kg/day

(e) No changes in the operation of a plant shall be made after a sludge test has been conducted which would potentially increase emissions above the level determined by the most recent sludge test, until the new emission level has been estimated by calculation and the results reported to the Control Officer.

(f) All sludge samples shall be analyzed for mercury content within 30 days after the sludge sample is collected. Each determination shall be reported to the Control Officer by a registered letter dispatched within 15 calendar days following the date such determination is completed.

(g) Records of sludge sampling, charging rate determination and other data needed to determine mercury content of wastewater treatment plant sludges shall be retained at the source and made available, for inspection by the Control Officer, for a minimum of 2 years.