| Violation ID |
Occurred Date |
Violation Type |
(-) Violation Description |
Corrective Action |
Status |
Classification |
Source |
| 1131497 |
07/22/2024 |
ATOX |
Acute Toxicity 3-Sample Median limit is 90 % survival and reported value was 85 % survival at EFF-001. |
The Acute Bioassay was repeated on 08/05/2024. The test result yielded a survival of 95% and the 3 sample median survival of 95%. |
Violation |
U |
eSMR |
| 1119668 |
07/07/2023 |
Deficient Reporting |
The analysis results for BOD samples (INF-001 and EFF-001) collected on July 7th are invalid because the tests failed the quality assurance and quality control (QA/QC) protocols for the test. Consequently, the District does not have the two valid BOD sample results required for the first week of July. The District reanalyzed the sample collected July 7th on July 13th. However, this test is beyond the acceptable hold time for BOD sampling. As such, these sample results are qualified in CIWQS as analyzed after the holding time expired. |
The District has renewed exploring the use of synthetic seed based on the information learned from other wastewater agencies. A reintroduced BOD synthetic seed study is in progress, and it has yielded some successful data but requires more testing. In the meantime, the lab will send INF-001 and EFF-001 BOD samples to a contract lab to ensure the compliance data is obtained to meet the permit requirements. The District will resume analyzing BOD tests in-house again after it completes a corrective action plan. |
Violation |
U |
eSMR |
| 1115063 |
02/01/2023 |
DMON |
The analysis results for the BOD samples collected on February 1st and 2nd are invalid because the tests failed the quality assurance and quality control (QA/QC) protocols for the test. Consequently, the District does not have the two BOD sample results required for the first week of February. The QA/QC failed because the Laboratory Control Samples (LCS) for the BOD samples collected on those two days were prepared with the incorrect standard.
The sample results for the Ammonia samples collected on February 8th and 9th were analyzed outside of the normal hold times. |
To prevent the reoccurrence of failing the LCS for BOD sampling, District staff has created a Chemical Receiving Procedure directing staff receiving standards or chemicals to identify the standard or chemical name on the container. In addition, the lab will update the BOD test Standard Operating Procedure (SOP) during the next revision to include language that requires the chemist
or analyst performing the sample test ensures the correct standards or reagents being used are verified before performing the analysis.
To prevent the reoccurrence of missing contract lab analysis, two chemists will review all contract lab work requests against the sample matrix to verify the completeness of the analysis requested.
|
Violation |
U |
eSMR |
| 1114026 |
01/04/2023 |
DMON |
The analysis results for BOD samples collected on January 4 and 6 were invalid because the tests failed the quality assurance and quality control (QA/QC) protocols for the test. Consequently, the District does not have the two BOD sample results required for the week of January 1st. District staff investigated the cause of the failed analysis and determined the QA/QC failure was related to the heavy storms that occurred during early January. The significant storms over-diluted the primary effluent used to seed the BOD. |
District staff is planning to implement a parallel seed study using synthetic seed in 45 days. The synthetic seed will be used in conjunction with the primary effluent seed. If the study proves successful, the District will be able to use synthetic seed for the BOD test. In addition, the lab has updated the BOD test Standard Operating Procedure (SOP) to collect additional BOD samples per week during large rainstorm events to avoid the deficiency in compliance monitoring for BOD. |
Violation |
U |
eSMR |
| 1112692 |
12/31/2022 |
UAUTHDISC |
On Saturday, December 31, 2022, the District experienced extraordinarily high influent flows throughout its satellite collection systems and conveyance system as a result of the atmospheric river that hit the Bay Area. There was an overflow in the headworks area of the Delta Diablo Wastewater Treatment Plant (WWTP) located at 2500 Pittsburg Antioch Hwy in Antioch, CA. A portion of the overflow, consisting of wastewater that had been screened and underwent grit removal, may have reached a stormwater drainage canal to the east of the WWTP. Most of the overflow was contained onsite and sent through the WWTP for full treatment. The overflow started at 1715 and ended at 1830 (75 minutes) at the grit chamber. The total overflow volume is estimated at 84,375 gallons and the flow travelled to the west, north, and east of the overflow point and was mostly contained on the WWTP site where it will be returned through the system for full treatment (80,625 gallons). The portion of the overflow that may have reached receiving waters is estimated to be 3,750 gallons (50 gallons per minute for 75 minutes). The involved waterway was the Los Medanos Wasteway, a drainage canal running north to south along the east side of the WWTP. CalOES was notified of the unauthorized discharge. No receiving water sampling was conducted as river conditions were deemed unsafe for staff during the storm event. Observations of the receiving waters could not be made due to the discharge being diluted by inflow and infiltration and due to the saturation of the area due to the rainfall. |
According to Delta Diablo staff, the storm event limited the District’s ability to attempt to take corrective actions as District staff were responding to multiple issues related to the storm. However, Delta Diablo expects the overflow to have minimal impacts. The sewage that overflowed was diluted by the storm inflow and infiltration. Average flow is typically 13.7 MGD and the average flow for that day was 33.1 MGD. Additionally, the Los Medanos Wasteway overflowed its banks and the floodwaters reached the District’s fence line. The diluted sewage was further diluted by the floodwaters.
Analysis of the incident indicated that the grit chamber overflowed when influent flows exceeded 43.38 MGD. As a short-term measure, the District placed sandbags along the fence line east of the headworks/grit area in anticipation of upcoming storms. The District will evaluate the options to install a permanent berm along the east side of the property near the headworks to prevent overflows from running off site since all on site runoff is contained and routed through the WWTP for full treatment or to develop a wet weather standard operating procedure to sandbag the area prior to large storms expected to generate over 40 MGD. |
Violation |
B |
Report |
| 1094648 |
08/05/2021 |
CAT2 |
Mercury, Total Weekly Average (Mean) limit is 0.072 ug/L and reported value was 0.086 ug/L at EFF-001. |
Delta Diablo is drafting an Action Plan for Mercury Reduction to address the mercury excursion. |
Violation |
U |
eSMR |
| 1093533 |
07/31/2021 |
CAT2 |
Copper, Total Recoverable Monthly Average (Mean) limit is 35 ug/L and reported value was 63 ug/L at EFF-001. |
Staff is investigating the cause for the elevated copper result. |
Violation |
U |
eSMR |
| 1093534 |
07/14/2021 |
CAT2 |
Copper, Total Recoverable Daily Maximum limit is 53 ug/L and reported value was 63 ug/L at EFF-001. |
Staff is investigating the cause for the elevated copper result. |
Violation |
U |
eSMR |
| 1080734 |
09/08/2020 |
CAT2 |
Chlorine, Total Residual Instantaneous Maximum limit is 0.0 mg/L and reported value was 0.12 mg/L at EFF-001. |
The SOP for the calibration of the SBS analyzers will be revised to improve the consistency on how the operators perform this calibration. The operators will be trained on the new procedure. |
Violation |
U |
eSMR |
|
Report displays most recent five years of violations. Refer to the Interactive Violation Report for more data.
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