Guidelines for rehabilitating mined land to irrigable standard

Managing or treating large volumes of mine water is expensive, and irrigation may be a beneficial, cost-effective option to consider. This enhances food security, and can improve livelihoods of nearby communities, especially post-closure, thereby supporting the Just Energy Transition. Suitable rehabilitated mined land in close proximity to such waters could be ideal for irrigation, as off-site environmental impacts are expected to be minimal and manageable if return flows accumulate in old pit voids and are contained. However, due to physical limitations, rehabilitated land is generally less favourable than unmined land for crop production. Technical Guidelines for Irrigation with Mine-Affected Waters (WRC report no. TT 855/2/21) and Guidance for attaining regulatory approval of irrigation as a large-scale sustainable use of mine water (WRC report no. TT 837/20), have been developed to facilitate informed decision-making and to promote the sustainability of this practice. Additionally, Land Rehabilitation Guidelines for Surface Coal Mines (LaRSSA 2019) provide guidance on how to rehabilitate mined land. However, guidance is required on how to rehabilitate mined land to irrigable and not just arable standards. Such guidelines should also contain procedures for the assessment of irrigability of rehabilitated land and offer recommendations for remediation of sub-optimal rehabilitated areas. The Guidelines for Rehabilitating Mined Land to Irrigable Standard presented here exclusively consider physical land and soil characteristics, as it is assumed that chemical limitations to crop production, such as soil fertility, are easier to address than physical limitations. Mine water is often of poor quality, requiring uniform irrigation application to reduce the risk of salinisation in irrigated fields. Due to the high risk of emitter blockage, mine water is unsuitable for micro-irrigation systems. Therefore, these guidelines assume that overhead centre-pivot irrigation, will be the preferred method for using mine water. These proposed guidelines expand on the LaRSSA 2019 guidelines, and are presented in three sections; SECTION A outlines the requirements for rehabilitation of mined land to irrigable standard, SECTION B presents the assessment of irrigation potential of rehabilitated mined land, and SECTION C recommends remediation approaches for areas of sub-optimal irrigability in rehabilitated mined land.