September 22, 1999

Sampling UCD LEHR Stormwater Runoff Aquatic Life Toxicity

Dr. Valerie Connor

Dear Val,

In response to the UCD Aquatic Toxicology Laboratory September 16, 1999 draft Summary of Proposed 1999-2000 UCD LEHR and Campus Storm Water Sampling, I have the following comments:

In the second sentence in the second paragraph, page 1 states that there are three surface drains originating from the LEHR site that convey overland flow to Putah Creek. That statement does not reflect the fact that stormwater from LEHR leaves the LEHR site also via discharges to the campus sewerage system. The discharges from the UCD campus wastewater treatment plant needs to be sampled during stormwater runoff events to determine if the addition of stormwater flow to the sewerage system causes an overloading of the system which then allows toxicity to flow through the plant into Putah Creek. This should be done early and late during stormwater runoff events. While it may be claimed by UCD that they are measuring toxicity in the effluent in accord with their NPDES permit requirements, unless these measurements are made at the time of stormwater runoff events they will not detect toxicants added to the campus sewerage system in the stormwater that is introduced to the system, as well as toxicants that pass through the treatment works because of the increased hydraulic loading of the treatment plant during runoff events.

Page 2, in the second paragraph, last sentence, discusses the difficulty of sampling the WWTP during stormwater runoff events using a single sample. It is necessary to sample several times during event.

Page 2, first paragraph under "INSTREAM", it is essential to sample downstream of the campus at Mace Blvd. every few hours over a runoff event. It is highly likely that chromium discharged from the campus through the wastewater treatment plant as part of remediating the campus "west" landfill polluted groundwaters, which are high in chromium, that is added to the campus sewerage system enters Putah Creek as chromium III and accumulates in the sediments. The chromium concentrations in the UCD wastewater plant discharge are often 5-10 g/L total chromium. During a runoff event the sediments are scoured and the chromium III begins to convert to chromium VI. Chromium VI is toxic to zooplankton at less than 0.5 g/L. This could be a source of toxicity downstream of the campus that is not measured unless samples are taken of Putah Creek after there is sufficient time for the chromium III to convert to chromium VI. Mace Blvd. may be too early, however it is the best sampling location available.

Yesterday the UCD ATL sent me a file which contained a virus. Fortunately my virus checker picked it up before it infected my computer. This is the second time that this has occurred. UCD ATL needs to obtain and maintain up to date a good virus checking program to keep from being a source of viruses to people who work with that laboratory.

Also yesterday, Karen Larsen informed me that UCD ATL did in fact send the sample of the July 21 San Diego Creek water to APPL for chemical analyses. They just obtained the data from APPL. According to Karen there was no record that the sample had been sent to APPL. You may recall that when I inquired about the data several weeks ago, I was told by Karen that the sample was never sent. This situation again points to the need to develop more appropriate sample handling procedures and recording at UCD ATL than has been occurring over the past several years.

If there are questions on these comments, please contact me.


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