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_.: ~-- Tom Gillis - 2 - May 4, 1990 Test Plot Mean Parameter Values by Soil Depth Soil Depth Tot Cov Cht Cov Tot Prod Cht Prod Shrub Density 6" 36.2'b 8.7a 306#/AC 25.3#/AC 905/AC 12" 47.5'b 13.2$ 481#/AC 51.3#/AC 616/AC 24" 52.6 13.28 595#/AC 113.7#/AC 377/AC 48" 37.6$ 5.2~ 606#/AC 23.D#/AC 174/AC Based on average Dlot values, it would appear that cover and production success standards are being met with the 6" soil cover depth, althouoh both cover and Droduction consistently increased as soil depth increased up to 24 inches. Shrub density shows an inverse relationship with soil depth althoua_h shrub height increases with soil depth. Establishment of seeded perennial forts was very poor across all test D1ots and the remainder of the 5.2 acre Roadside Refuse Pile, which received 6" of cover soil and was seeded concurrently with the test plots. The noxious weed whitetop (Cardaria drabs) has become established within two of the test plots and other portions one refuse area and will need to be controlled to prevent further spread. Concerns expressed previously by the Division based on the 1986 evaluation included the need for verification of cover soil depths, dominance of cheatarass and absence of desirable forts, and the need for concurrent reference area data collection. The 1989 report includes soil depth documentation and reference area data. cheatarass abundance was much reduced on all plots in 1988 and was not apparent during my inspection in April of this year. Perennial fort abundance does not appear to have increased since 1986, with the exception of the undesirable noxious weed, whitetop. Soi1JlJaste-Analyses Soils in the general area are typically shallow sandy foams with sodic or saline/sodic subsoils. These conditions, combined with the relative aridity of the region account for the nature of the native vegetative communities which are dominated by low crowing salt tolerant shrubs. Based on the available analyses of the coal waste, its primary limitations as a a_rowth medium are probably its coarse texture (low water holding capacity) and black color. pH and SAR levels, while high, are within the range encountered in the native subsoils. Soil samples taken at incremental depths within the test plots indicate that no upward migration of sodium or other salts has occurred. Recommendations For the Cameo Refuse Disposal areas, I would preliminarily recommend a minimum soil replacement depth of 12", assuming that additional coal waste analyses confirm that the material in the Cameo piles is comparable to that in the Roadside pile. At least 2 analyses representative of portions of CRDA #1 and #2 which have been in place for more than one year will need to be submitted with the TR application. A recommended parai,titer list is attached.