2009-06-08_REVISION - M1997032 (19)

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Denison Mines USA Corp - Van 4 Shaft Monogram Mesa November 17, 2008 Page 2 • a. Additional Information: The following additional information is required for each sampling event: -the date and duration (in hours) of the storm event(s) sampled; -rainfall measurements or estimates (in inches) of the storm event which generated the sampled runoff; -the duration between the storm event sampled and the end of the previous measurable (greater than 0.1 inch rainfall) storm event; -an estimate of the size of the drainage area (in square feet) and an estimate of the runoff coefficient of the drainage area (e.g. low (under 40%), medium (40% to 65%) or high (above 65%)); and -an estimate of the total volume (in gallons) of the discharge sampled. b. Sampling Procedures: For facilities with holding ponds or other impoundments, sampling shall be performed at the outlet from the pond. If no discharge from the pond to surface waters occurs, then no sampling is necessary. Please note that if any process water mixes with stormwater, all of the water is considered to be process water and must be covered under a CDPS industrial wastewater discharge permit. All such samples shall be collected from the discharge resulting from a storm event that is greater than 0.1 inches in magnitude and that occurs at least 72 hours from the previously measurable (greater than 0.1 inch rainfall) storm event. If the collection of a sample cannot be obtained occurring at least 72 hours from the previous measurable event, the sample must be taken from a storm event meeting conditions as close to these as possible, and the discharger shall submit with the monitoring report a description of why obtaining a sample at least 72 hours following the previous measurable event was not possible. • The grab sample shall be taken during the first thirty minutes of the discharge. If the collection of a grab sample during the first thirty minutes is impracticable, a grab sample can be taken during the first hour of the discharge, and the discharger shall submit with the monitoring report a description of why a grab sample during the first thirty minutes was impracticable. The first two samples per discharge point must be taken between now and December 31, 2009, and reported to our office with your next Annual Report. Given that the weather does not always cooperate, it may not always be possible to get a sample during business hours. This will not be considered an adequate excuse for not having sampled. The Division strongly recommends that you contact a lab prior to setting up your sampling program (see guidance document). Parameter List Enclosed is a list, specific to your facility, of parameters that you must sample for. It is based on the Division's evaluation of potential pollutants of concern from the Van 4 Shaft Monogram Mesa facility. Sampling Points Your Stormwater Management Plan (SWMP) must be modified to include a description of your sampling point(s). Remember that the sampling point should be representative of where the pollutants of concern occur. One DMR form is required for each sampling point. SWMP The SWMP prepared for the Van 4 Shaft Monogram Mesa facility, revised to describe each sampling point, must be submitted to the Colorado Department of Public Health and Environment, WQCD-P-B2, 4300 Cherry Creek Drive South, Denver, CO 80246-1530, Attn: Kathleen Rosow by December 17, 2008.