(1) The frequency of monitoring required by this section is based on the dry weight tonnage of bulk biosolids applied to the land per three hundred sixty-five-day period or the dry weight tonnage of biosolids received per three hundred sixty-five-day period by a person who prepares biosolids that are sold or given away for application to the land.

(2) The person who prepares biosolids is responsible for ensuring that monitoring is carried out in accordance with the requirements of this chapter and any applicable permit.

(3) The minimum frequency of monitoring listed below applies to the pollutants listed in Tables 1, 2, and 3 of WAC 173-308-160, the pathogen density requirements in WAC 173-308-170, and the vector attraction reduction requirements in WAC 173-308-180.

MINIMUM FREQUENCY OF MONITORING

Metric tons (U.S. tons) per 365-day period	Frequency
Greater than zero but less than 290 (320)	once per year
Equal to or greater than 290 (320) but less than 1,500 (1,653)	once per quarter (4 times per year)
Equal to or greater than 1,500 (1,653) but less than 15,000 (16,535)	once per 60 days (6 times per year)
Equal to or greater than 15,000 (16,535)	once per month (12 times per year)

(4) Treatment works treating domestic sewage that transfer biosolids or sewage sludge for further treatment to another facility are not required to monitor for pollutant concentrations, pathogen reduction, or vector attraction reduction unless specifically required to do so in a permit issued by the department.

(5) After the biosolids have been monitored for two years at the frequency in this section, the person who prepares the biosolids may request the department to reduce the frequency of monitoring for pollutant concentrations. The frequency of monitoring must not be less than once per year when biosolids are applied to the land.

PDFWAC 173-308-150

Frequency of biosolids monitoring.