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4.05.8(1) <br />prime farmland subsoil should be approved by the RA, in consultation with the NRCS, <br />only when the substitute material will have a demonstrated productivity that is equal to <br />or higher than the original subsoil. <br />Soil Replacement and Reconstruction <br />(e) The reaction (pH) and other chemical properties of the major horizon of the <br />reconstructed soil must be within the ranges of the pre -mined soil or be more favorable <br />for plant growth. <br />The suitability criteria for the soil and substitute material have been altered with the <br />approval of PR -6 (Le. from 4 mmhos /cm to 6 mmhos /cm). According to Colorado State <br />University Extension Bulletin Number 0.503, Managing Saline Soils, a replaced growth <br />medium that allows an EC of 6 mmhos /cm has strong potential to be toxic to corn as well as <br />have a detrimental impact to alfalfa production and forage crops. The publication <br />illustrates that corn grown in soils with an EC of 5.9 can potentially see a relative yield <br />decrease of 50% and alfalfa could have a 25% decrease in yield with a soil EC of 5.4. <br />Considering that alfalfa is the target crop for demonstrating the yield capability of the <br />reclaimed prime farmland and that corn is likely to be a primary rotational crop after the <br />land is returned to the landowner, approval of an EC threshold of 6 mmhos /cm for <br />affirming the quality of the growth media to be used for reclamation is not in compliance <br />with the regulations at 4.05.8(1), 2.06.6 (2) (d), and 4.06.2 (4) (a) of the Colorado State <br />Program. For reference, these regulations read as follows: <br />Identifying, burying, and treating where necessary, spoil and waste which may be <br />detrimental to vegetation, public health or safety or may adversely affect water quality if <br />not treated or buries. <br />2.06.6(2) (d) <br />If applicable, documentation, such as agricultural school studies or other scientific data <br />from comparable areas, that supports the use of other suitable material, instead of the A, <br />B, or C soil horizons, to obtain on the restored area equivalent or higher levels of yield <br />as non -mined prime farmlands in the surrounding area under equivalent levels of <br />management. <br />4.06.2(4) (a) <br />Selected overburden materials may be substituted for, or used as supplement to topsoil, <br />if the Division determines that the resulting soil medium is equal to or more suitable for <br />sustaining the vegetation than is the available topsoil and the resulting soil medium is the <br />best available in the permit area to support revegetation. This determination shall be <br />based on: <br />17 <br />