StormceptorŽ Monitoring Protocol

The table below indicates the pollutants to be monitored during storm events, as well as the acceptable detection limit for each pollutant that needs analyzing. Approved federal and state laboratory analysis methodologies must be used for analysis.

Optional metals indicated in Table 1 refer to the Resource Conservation Recovery Act and may be covered by a generic metals scan. Two sediment samples must be extracted from the monitored StormceptorŽ at the end of each study for analysis of the particle size distribution and water content. A minimum of 10 particle sizes must be used to determine the particle size distribution. Sieves used include: 35, 60, 100, 140, 200, 270 and 400 size. Three clay particle sizes must be analyzed to determine particle sizes between 5 and 25 u.m. The particle size distributions should be plotted on a standard grain size distribution graph.

 

Table 1. Monitored Pollutants
Pollutant Minimum Detection Limit (MDL)

Total Suspended Solids (TSS)

5 mg/l

Total Phosphorus (P)

0.02 mg/l

Total Kjeldahl Nitrogen (TKN)

0.1 mg/l

Copper (Cu)

0.001 mg/l

Cadmium (Cd)

0.005 mg/l

Lead (Pb)

0.05 mg/l

Zinc (Zn)

0.01 mg/l

Chromium (Cr)

0.01 mg/l

Total Petroleum Hydrocarbons (TPH)

1 mg/l

Conductivity

0.1 m mho/cm

Fecal Coliform *

1 /100 ml

 

Additional Metals (optional)

 

Arsenic (As)

0.005 mg/l

Barium (Ba)

0.01 mg/l

Mercury (Hg)

0.0005 mg/l

Selenium (Se)

0.005 mg/l

Silver (Ag)

0.01 mg/l

1. Monitoring protocols should conform to EPA 40 CFR, Part 136.

2. The EPA guideline requires a 72 hour dry period prior to a monitoring event. This ensures there is sufficient pollutant build-up for wash-off during the monitored event.

3. Flow proportional monitoring must be conducted for the parameters indicated in Table 1. Samples should be analyzed separately for the first flush versus the remainder of the storm event. Monitoring does not need to extend longer than an 8-hour period after the beginning of the storm event (composite).

4. Sediment sampling (measuring the unit sediment depth at the beginning and end of the monitoring period) must be conducted. The water content of the sediment layer must be analyzed to determine the dry volume of suspended solids. Sediment depth sampling will indicate the rate of pollution accumulation in the unit, provide confirmation that the unit is not scouring and confirm the flow proportional monitoring results. A mass balance using the sediment sampling should be calculated to validate the flow proportional sampling.

5. Grab sampling (samples from the inlet and outlet) is an unacceptable methodology for testing the performance of the StormceptorŽ during wet weather conditions. The oil containment area underneath the insert should be inspected via the vent pipe for dry weather spills capture once a month during the monitoring period since the flow rate of a dry weather spill may not trigger the automated samplers.

6. A tipping bucket rain gauge should be installed on-site to record the distribution of storm intensities and rainfall volume during the monitored events.

7. Results within the laboratory error (both inlet and outlet) or are representative of relatively clean water should be discarded. Typical concentrations of pollutants in stormwater are:

TSS

100mg/L

Total P

0.33mg/L

TKN

1.50mg/L

Total Cu

34µg/L

Total Pb

144µg/L

Total Zn

160µg/L

A threshold first flush/composite TSS value of 50 mg/L at the inlet to the StormceptorŽ should be used as the lower limit of an acceptable storm for reporting event efficiency. Monitoring results where the influent TSS concentration is less than 50 mg/L should only be used in mass load removal calculations over the entire monitoring period with other storms where the influent concentration is greater than 50 mg/L. The results should not be analyzed if the influent TSS concentrations during all monitored storms are less than 50 mg/L. Storms where the influent TSS concentration is less than 10 mg/L should be discarded from all analyses.

Monitoring Methodology: The following monitoring protocol should be followed to ensure reasonable monitoring results and interpretation.

1. Monitoring protocols should conform to EPA 40 CFR, Part 136.

2. The EPA guideline requires a 72 hour dry period prior to a monitoring event. This ensures there is sufficient pollutant build-up for wash-off during the monitored event.

3. Flow proportional monitoring must be conducted for the parameters indicated in Table 1. Samples should be analyzed separately for the first flush versus the remainder of the storm event. Monitoring does not need to extend longer than an 8-hour period after the beginning of the storm event (composite).

4. Sediment sampling (measuring the unit sediment depth at the beginning and end of the monitoring period) must be conducted. The water content of the sediment layer must be analyzed to determine the dry volume of suspended solids. Sediment depth sampling will indicate the rate of pollution accumulation in the unit, provide confirmation that the unit is not scouring and confirm the flow proportional monitoring results. A mass balance using the sediment sampling should be calculated to validate the flow proportional sampling.

5. Grab sampling (samples from the inlet and outlet) is an unacceptable methodology for testing the performance of the StormceptorŽ during wet weather conditions. The oil containment area underneath the insert should be inspected via the vent pipe for dry weather spills capture once a month during the monitoring period since the flow rate of a dry weather spill may not trigger the automated samplers.

6. A tipping bucket rain gauge should be installed on-site to record the distribution of storm intensities and rainfall volume during the monitored events.

7. Results within the laboratory error (both inlet and outlet) or are representative of relatively clean water should be discarded. Typical concentrations of pollutants in stormwater are:

TSS 100mg/L Total P 0.33mg/L TKN 1.50mg/L Total Cu 34mg/L Total Pb 144mg/L Total Zn 160mg/L

A threshold first flush/composite TSS value of 50 mg/L at the inlet to the StormceptorŽ should be used as the lower limit of an acceptable storm for reporting event efficiency. Monitoring results where the influent TSS concentration is less than 50 mg/L should only be used in mass load removal calculations over the entire monitoring period with other storms where the influent concentration is greater than 50 mg/L. The results should not be analyzed if the influent TSS concentrations during all monitored storms are less than 50 mg/L. Storms where the influent TSS concentration is less than 10 mg/L should be discarded from all analyses.

8. A threshold storm event volume equal to 1.5 times the storage volume of the StormceptorŽ being monitored should be used as the lower limit of an acceptable storm for monitoring.

9. The personnel monitoring the StormceptorŽ should record incidental information in a log file. Information such as weather, site conditions, inspection and maintenance information, monitoring equipment failure, etc. provide valuable information that can explain anomalous results.

10. Laboratory results of monitored samples should be analyzed within 10 days of being submitted to the lab.

11. Weekly inspections of the sampling tubes, flow meter, rain gauge, and quality samplers should be conducted to ensure proper operation of the monitoring equipment. Debris and sediment that collects around the sampling intakes should be cleaned after each event.

12. During the installation of automated quality samplers, care should be exercised to ensure that representative samples will be extracted (placement of intakes, ensuring that tubing is not constricted or crimped).

13. Sampling should be conducted for a minimum of 6 storms. Ideally, 15 storms should be sampled.

For more information, contact the Rinker StormceptorŽ office at (800) 909-7763.