Procedures for assessment of cumulative impacts of coal mining on the hydrologic balance

Abstract

The Surface Mining Control and Reclamation Act of 1977 requires the designated regulatory authority of each State to assess the probable cumulative impacts of all anticipated mining upon the hydrology of the area. The Act also states that quantity and quality of water is to be considered as well as seasonal variations in flow. Techniques were developed to assess the probable cumulative impacts including concepts of a hydrologic activity profile, an impact matrix, and an impact profile. An activity profile of cumulative drainage area versus river miles downstream from the surface-mining site is constructed that shows major water uses, flood-prone areas, and stream classifications. From the summary shown by the activity profile, an impact matrix is used as a checklist for the probable importance of the impacts under categories such as water supply, flood-prone areas, and water-contact recreation. These impacts are quantified either by a simple model or a more comprehensive and accurate one and are displayed on an impact profile showing the percentage change in a hydrologic characteristic versus distance downstream of the surface-mining site. The simple model for quantification considers only dilution from tributary areas during critical periods, whereas the comprehensive model routes flows and quality of water continuously through the year and considers, in addition to dilution, instream processes such as settling, biological uptake, and chemical reactions. INTRODUCTION Purpose and Scope The purpose of this report is to present procedures for assessing the cumulative impact of coal mining on the hydrologic balance. Four steps were used to develop the procedure. First, a review was made of the appropriate sections of the Surface Mining Control and Reclamation Act of 1977 and the associated regulations so that the requirements for the assessments could be identified and the technical terms could be defined. Next, the technical literature was reviewed for evaluations and comparisons of methods for hydrologic analysis. Both simplified and comprehensive computer methods are reviewed. Third, available hydrologic methods were selected and a five-step procedure was developed. Fourth, the procedure was illustrated with a case study. Legislative Requirements P.L. 95-87, Surface Mining Control and Reclamation Act of 1977, Sections 101(c) and 101(h), summarize the problems related to surface mining: ( c ) »* many surface-mining operations result in disturbances of surface areas that burden and adversely affect commerce and the public welfare by destroying or diminishing the utility of land for commercial, industrial, residential, recreational, agricultural, and forestry purposes by causing erosion and landslides, by contributing to floods, by polluting the water, by destroying fish and wildlife habitats, by impairing natural beauty, by damaging the property of citizens, by creating hazards dangerous to life and property, and by degrading the quality of life in local communities and by counteracting governmental programs and efforts to conserve soil, water, and other natural resources * there are a substantial number of acres of land throughout major regions of the United States disturbed by surface and underground coal on which little or no reclamation was conducted, and the impacts from these unreclaimed lands impose social and economic costs on residents in nearby and adjoining areas as well as continuing to impair environmental quality *; A principal purpose of the Act is to protect society and the environment from the adverse effects of surface coal -mining operations and minimize the adverse effect of abandoned mines. A permit program is established to regulate surface-mining operations, eventually to be enforced by the States. As part of the permit application and review procedures, determination of the probable hydrologic consequences is made by the operator or a qualified public or private laboratory (Sections 507(b)(ll) and 507(c)). Of most concern herein, the approval of the permit requires as stated in Section 510(b)(3): * the assessment of the probable cumulative impact of all anticipated mining in the area on the hydrologic balance specified in Section 507(b) has been made by the regulatory authority and the proposed operation thereof has been designed to prevent material damage to hydrologic balance outside permit area *. And prior to approval, the application for a permit must contain as stated in Section 507(b)(ll): * a determination of the probable hydrologic consequences of the mining and reclamation operations, both on and off the mine site, with respect to the hydrologic regime, quantity and quality of water in surfaceand ground-water systems, including the dissolved and suspended solids under seasonal flow conditions, and the collection of sufficient data for the mine site and surrounding areas so that an assessment can be made by the regulatory authority of the probable cumulative impacts of all anticipated mining in the area upon the hydrology of the area and particularly upon the water availability *.