2009-12-18_REVISION - C1981008 (4)

Home Browse Search

United States Department of Agriculture gNKS Natural Resources Conservation Service Jim Boyd. Resource conservationist P. O. Box 29 Norwood, CO 81423 DEC 18 2009 GRAND JUN,c Itiiu FIELD OFFICE D1vhlON OF RECLp,t!RTION MINING & SAFETY December 8, 2009 Division of Reclamation, Mining and Safety Department of Natural Resources 101 South 3'd Street, Suite 301 Grand Junction, CO 81501 Dear Concerned Parties: C08ioo? a Pkh jim.boyd@co.usdagov 970-327-4245-OFFICE 970-3274247-FAX In response to the Western Fuels NuclalPermit Revision 2009\Final Files\2.05.4(2)(e), I am once again called upon to challenge and correct the data and calculations regarding irrigation design that have been submitted by Western Fuels. First and foremost, I am re-submitting all prior letters and irrigation design calculations pertaining to MRCS design criteria for sprinkler irrigation of alfalfa hay in the Nucla, Colorado area. In Attachment 2.05.4(2)(e)-7-2 through Attachment 2.05.4(2)(e)-7-5, Western Fuels and Greg Lewicki & Associates present calculations of evapotranspiration (ET), using the Blaney-Criddle method, for irrigated cropland on the Morgan Property of the New Horizon #2 Mine based on what they consider "site specific data and the accepted scientific processes for determining the water requirements of alfalfa." Unfortunately their results are inherently flawed for a couple of reasons. First off, the Blaney-Criddle formula (ET = k x tp/100), relies on mean monthly air temperature (t) in its calculation. The site specific monthly air temperatures used in Western Fuel's calculations for ET were collected from a weather station mounted to the exterior wall (south- facing no less), of the mine office in Nucla. These temperature values are unreliable for many reasons, the main one being the location of the weather station. This weather station is very near the roof of the building, the roof being of metal construction. Also, there is a metal sided trailer/building located a mere twenty feet south of the weather station, and the area surrounding these buildings is concrete sidewalk, asphalt pavement, gravel and the lice. Needless to say the temperature values collected from this weather station, due to its location, can not be relied upon to be representative of the ambient air temperature near an irrigated crop field in the Nucla area There are very strict standards and specifications for locating and installing weather stations for the purpose of collecting reliable and representative weather data to be used for scientific purposes. For example, the temperature data used by NRCS in calculating ET values comes from a weather station located at an agricultural research facility near Cortez, Colorado. One of the requirements for locating such a weather station is that it be placed within a vegetated landscape and away from buildings and trees. Furthermore, field trials have been conducted at the research facility by agricultural scientists to measure consumptive water use of various crops for development of crop coefficients to be used for ET calculations. The crop coefficients used The Natural Resource Conservation Service works in partnership with the American People to conserve and sustain natural resources on private lands. An Equal Opportunity Provider and Employer.