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  • Brianne Archer, PE

NPDES and WDR Self-Monitoring


It’s common in Southern California to discharge groundwater from dewatering operations (for instance, with a sump pump such as the one on the left)in subterranean building structures , such as a parking garage or basement, to the nearby storm sewer.

The dewatering is necessary to protect the integrity of the building structure from rising groundwater. Within the jurisdiction of the Los Angeles Regional Water Quality Control Board (LARWQCB), the practice is regulated under general NPDES [National Pollutant Discharge Elimination System] permit No. CAG994004 and Waste Discharge Requirements (WDRs) established under Order No. R4-2013-0095, the Waste Discharge Requirements for Groundwater Discharges from Construction and Project Dewatering to Surface Waters in Coastal Watersheds of Los Angeles and Ventura Counties.

To comply with the NPDES permit and WDRs, dischargers must continuously monitor effluent flow and collect monthly samples for the analysis of: pH, temperature, total suspended solids, turbidity, BOD5, oil and grease, settleable solids, sulfides, phenols, residual chlorine, and methylene blue active substances. Quarterly, analyses include total recoverable copper, lead, selenium, and zinc. Annually, acute toxicity analysis is required.

Self Monitoring Reports must be submitted electronically to the LARWQCB on a quarterly basis, within six weeks of the end of the quarter. The monitoring report should state whether there was any change in the discharge during the reporting period. Monitoring reports must include the WDR discharge limitations, tabulated analytical data, the chain of custody form, and the laboratory report (including but not limited to date and time of sampling, date of analyses, method of analysis, and detection limits). The reports must also contain a section titled “Summary of Non-Compliance” which discusses the compliance record and corrective action taken or planned that may be needed to bring the discharge into full compliance with WDRs. This section will list all non-compliance with WDRs and exceedances of effluent limitations.

The discharger must prepare and implement an acceptable quality assurance plan for laboratory analyses. At least once a year, the Discharger must submit a list of the analytical methods employed and associated laboratory QA/QC procedures. The annual monitoring report will summarize the QA activities for the previous year. Duplicate chemical analyses must be conducted, at least one sample per sampling period.

Violations and Fines for Non-Compliance

The LARWQCB has the authority to issue violations and collect fines for late reporting and exceedances of effluent limitations. Mandatory minimum penalties ($3,000) accrue monthly on the 16th of every month. The Water Board may also seek discretionary penalties for violations that are not corrected. Waterstone recommends that companies with outstanding violations move as swiftly as possible and start working with their legal counsel to negotiate with LARWQCB staff while simultaneously coming up to date with their backlogged self-monitoring reports with the help of an environmental professional.

Standard Operating Procedure (SOP)

Although not required by the WDRs/NPDES permit, Waterstone has worked with NPDES clients that were asked by the LARWQCB to prepare SOPs for the sampling, analysis, and flow monitoring activities to be performed in accordance with the permit. The LARWQCB requested that the SOPs be developed and implemented as part of an enforcement action following multiple late reporting violations and effluent limitation violations. Utilization of an SOP allows for consistency and maintenance of institutional knowledge in the event of a staff change and encourages the facility to follow best management practices. Waterstone finds that preparing a formal SOP extremely useful tool and a proactive step that should be implemented by all dischargers.

#larwqcb #npdes #groundwaterdischarge #wdr

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