Rule 3:19 Hexavalent Chromium Airborne Toxic Control Measure For
Cooling Towers
a. Definitions:
Cooling Tower: Any open water recirculation device
that evaporates circulating water to remove heat from a
process, building, or refrigeration device, and puts
the heat into the ambient air.
Hexavalent Chromium: A cancer-causing substance
existing as part of various inorganic chromate
compounds, for example, sodium dichromate or lead
chromate.
Water Treatment Chemicals: Any combination of
chemicals added to cooling tower water including
tracers, corrosion inhibitors, anti-scalants,
dispersants, biocides.
b. Requirements
1. Hexavalent Chromium Removal: Effective October 2,
1990, no person shall add any hexavalent
chromium-containing chemicals or any compound that
may produce hexavalent chromium to a cooling tower
operating in the District.
2. Circulating Water Concentration - Wooden Cooling Towers
Effective October 2, 1990, no person shall operate
a wooden cooling tower in the District unless the
following requirements are met:
A. From October 2, 1990, to March 12, 1991,
hexavalent chromium levels in the circulating
water are not to exceed eight (8)
milligrams/liter of circulating water.
B. After March 12, 1991, hexavalent chromium
levels in the circulating water are not to
exceed 0.15 milligrams/liter of circulating
water.
C. A decrease in hexavalent concentration in the
circulating water must be demonstrated each
month during a period of up to six (6) months
following the compliance date in order to
avoid being cited for a violation of the 0.15
milligram/liter limit.
Rule 3:19.b
3. Circulating Water Concentration -- Non-Wooden Cooling Towers
Effective October 2, 1990, no person shall operate
a non-wooden cooling tower unless the hexavalent
chromium levels do not exceed 0.15
milligrams/liter of circulating water.
c. Reporting
1. By December 12, 1990, any owner/operator of a
cooling tower shall notify the District in writing
regarding the following information about the
cooling tower.
Any owner/operator of a newly constructed cooling
tower shall provide the District with the
following information at least ninety (90) days
before the tower is operated:
A. Owner/operator of the tower,
B. Location of the tower,
C. Cooling tower type and materials of
construction,
D. Whether hexavalent chromium-based treatment
chemicals were ever used in the cooling
tower,
E. If hexavalent chromium based chemicals were
previously used, the date they were
discontinued,
F. A description of the alternate treatment
program chosen, as well as the circulating
water monitoring plan.
Rule 3:19
d. Monitoring - General
1. Effective October 2, 1990, any person subject to
the requirements of b.2 or b.3 shall test the
circulating water in the cooling tower at least
once every six (6) calendar months to determine
the concentration of hexavalent chromium.
Testing may be discontinued when two consecutive
required tests show hexavalent chromium
concentrations less than 0.15 milligrams/liter of
circulating water.
The District may require testing of the
circulating water at any time if the District has
reason to believe the water may contain hexavalent
chromium.
2. Any person subject to the monitoring requirements
in d.1 or e.1 below shall maintain records of the
results of all required tests of circulating water
for two (2) years and provide them to the District
upon request.
3. Monitoring requirements may be waived by the
District for any owner/operator of a cooling tower
who demonstrates to the District that the
hexavalent chromium based treatment chemical has
never been used in the cooling tower or has not
been used for a period of at least one (1) year
prior to the appropriate compliance date.
e. Monitoring of Wooden Cooling Towers
1. Any person subject to the requirements of b.2(B)
shall test the circulating water at least once
every calendar month to determine the
concentration of hexavalent chromium.
f. Determination of Hexavalent Chromium Content
1. Samples of circulating water shall be analyzed for
hexavalent chromium using American Public Health
Association Method 312 B or an equivalent method
approved by the District.
(Added 10-2-90)
REVISED 12/23/92