Cooling towers are used to air condition computer and animal research facilities as well as to provide cooling water for laboratory use. To save money on a short-term basis, sometimes no cooling towers are constructed and/or no back-up cooling systems are put in place. In these instances, straight EBMUD water is piped through the system for cooling purposes. This results in excessive water consumption as well as scaling of the piping, and is fairly expensive over the long term. Some cooling towers also constantly overflow to control excessive slime and solids which float to the top of the towers and are subsequently flushed out.
A variety of chemicals are added to some or all of the cooling towers to prevent clogging or scaling of the piping systems. These chemicals currently include:
- Polyethylene Ethylene Dichloride
- Tributyl Tin Neodecanoate
- Potassium Phosphonobutane
- Potassium Diphosphonate
- Polymeric, Cationic Electrolyte
- Triazole Inhibitor
- Surfactants
- Aliphatic Glycol
- Sodium Hydroxide
- Sodium Dichloro-S-Triazine Trione, Dihydrate Chlorine (phasing out)
- Sodium Nitrite (phasing out)
- Sodium Chromate (phasing out)
- 5-chloro-2-methyl-4-isothiazolin-3-one (phasing out) 2-methyl-4-isothiazolin-3-one (phasing out)
Blow-down of the cooling towers is done once a week to maintain a low solids content Small towers are only blown down about once a month. This purging discharge contains a high solids content and the various treatment chemicals. A significant number of the cooling towers on campus discharge into the storm sewer system and hence, the creek.
There are approximately_ 36 University operated cooling towers in the watershed, 16 of which were reported to discharge into the storm sewer system (Grove, 1970). This does not include any possible cooling tower discharges from LBL. Grove reported the following building cooling towers discharged to the storm sewer system:
- Campbell Hall (2) Space Sciences
- Donner Lab
- Cory Hall
- Davis Hall (3rd floor) Etcheverry Hall (4) University Hall
- Moffitt Library
- Life Sciences Building (2) Latimer Hall
- Birge Hall
In addition to these reportedly discharging to the storm sewer system, another 11 towers were reported to be possibly discharging to the sanitary sewer system, but this was not certain. The remaining tower discharges could not be identified. It is not accurately known how many towers discharge into the creek or what the water quality impacts of these discharges are at this time.