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Dowe Flats Quarry Soils and Geology Report <br /> 1 Introduction <br /> The CEMEX, Inc. Dowe Flats Quarry (Dowe Flats) is a limestone quarry located near the Town <br /> of Lyons in Boulder County, Colorado. Dowe Flats currently operates under Boulder County <br /> Special Use Permit (SUP) number SU-93-14. CEMEX, Inc. is seeking to amend our SUP to <br /> extend mining within the current footprint for an additional 15 years. The soils and geology of <br /> the Dowe Flats property were described in detail in the original 1993 SUP Application to <br /> Boulder County prepared by SHB AGRA (1993). This document updates and summarizes the <br /> information previously submitted. The activities proposed in CEMEX, Inc.'s current permit <br /> amendment application do not disturb any new areas. <br /> 2 Soils <br /> Soils of the Dowe Flats property were mapped by the U.S. Soil Conservation Service (now the <br /> Natural Resources Conservation Service, NRCS) in 1975 as part of the Boulder County Soil <br /> Survey (Moreland and Moreland 1975). This survey was updated in 2008 (Moreland and <br /> Moreland 2008). There was very little change in the soil classifications at Dowe Flats from 1975 <br /> to 2008; however, this document does follow the 2008 survey and the NRCS Web Soil Survey <br /> data (Soil Survey Staff 2021). <br /> 2.1 Soil Classification&Descriptions <br /> Soil samples were collected at the time of the original permit application to verify soil unit <br /> boundaries and determine reclamation suitability. Slight modifications to the boundaries of soil <br /> units were made at that time but were not considered critical because all material was verified as <br /> suitable for revegetation, and all units were salvageable to similar depths. In further support of <br /> this, reclamation activities completed on the site to date have proven the soils are suitable to <br /> reestablish healthy vegetation. <br /> 2.1.1 Main Soil Types of the Permit Area <br /> The three main soil units mapped in areas that were disturbed by mining are LaPorte very fine <br /> sandy loam, Manvel loam, and Gaynor silty clay loam. <br /> 2.1.1.1 Manvel Soils <br /> The Manvel soils covered approximately 50% of the property based on the NRCS mapping <br /> (Moreland and Moreland 2008). They are deep and well-drained, developing on calcareous, <br /> loamy alluvium. These soils were found on the broad central areas of Dowe Flats, away from <br /> limestone outcrops. Permeability in this soil is moderate and water holding capacity is low. The <br /> upper A-horizon layer was a brown loam about 6 inches thick. The underlying layer was a pale <br /> brown loam about 14 inches thick. Below this, was a dark grayish brown to dark brown silty clay <br /> loam extending to about 60 inches. The thickness of the surface material likely to be salvaged for <br /> reclamation varied from 4 to 6 inches. <br /> 2.1.1.2 LaPorte Soils <br /> The LaPorte soils covered approximately 31% of the property based on the NRCS mapping <br /> (Moreland and Moreland 2008). They are shallow and well-drained, developing over limestone <br /> and limey shale. They have moderate permeability, but because of their shallowness have low <br /> water-retention capacity. The upper A-horizon at Dowe Flats was a dark brown sandy loam from <br /> 1 May 2, 2022 <br />