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<br /> <br />ExxonMobfl Global Services <br />Colony Shale Oil Project <br />ESR Reclamation Studies <br />Weighing Lysimeter Performance 1990-2003 <br />Project No. 353 <br />Page 18 <br />design. One of the outputs, in fact the primary purpose of HELP, is percolate quantity which can be <br />used to check the capacity of the under drain system. To arrive at this quantity, the HELP model must <br />estimate runoff, changes in storage, and evapotranspiration. We have plotted the evapotranspiration <br />results of yeaz 13 of this 100 yeaz simulation because that particular year of the simulation was based <br />on 19.45 inches of annual rain, which corresponds to Colony's average of 19.45 inches for the years <br />1990 through 2003. However, the monthly splits of this 19.45 inches are a statistical creation, and <br />these do not match the actual measured precipitation amounts. The HELP output of deep percolation <br />quantities is nevertheless close to what was observed in the lysimeter, and the implied Et curve has <br />similaz shape to that actually observed (see Fig. 4.3). However, HELP seems to have overestimated <br />evapotranspiration in the spring, and the underestimated it in the late summer. <br />We believe that the model could be adjusted, by varying the nmoff coefficient for example, to <br />better match the observed evapotranspiration, but the model is not structured to allow direct review of <br />an individual year or a short series of years. <br />4.3 Yeaz-by-yeaz Summary Narrative <br />The following narrative provides a description on a year-to yeaz basis. It makes frequent <br />reference to observations in Fig. 4.1 and the yeaz-by-year summaries presented in Appendix B. <br />4.3.1 1990 - YE 1992 <br />The ESR plots had been constructed in late 1988, and then seeded in the fall of 1989, <br />using the nom~al late-fall seeding techniques in practice then at Colony and expected to be <br />used in future reclamation. Therefore, the plants would be gPrminat,,'ng in the spring of 1990, <br />and would not be mature for several years. <br />]huing these years the lysimeter seasonally gained net weight (black trace on Fig 4.1) <br />. presumably as spring melt and rainfall water percolated through the topsoil with only minimal <br />LACHEL FELICE & Associates <br />