Minera Yanacocha S.A. (Newmont) has an operating gold mine and associated heap-leach facility in the northern Peruvian Andes at an altitude of 3800 to 4,120 m. The mine is the largest gold producer in South America.

In 2005, Water Management Consultants (WMC) was asked to develop a numerical groundwater flow model in support of the Yanacocha Supplemental Oeste Environmental Impact Assessment, a project which aimed to integrate the Yanacocha - La Quinua pit complex and associated heap leach and waste rock facilities under a single environmental permit and allow for added expansions of mining. The model, which was developed in Modflow using Groundwater Vistas, covered an area of 120 km2 and incorporated 6 pit areas, 3 heap leach pads and 3 waste rock facilities. The numerical model was used to simulate potential environmental impacts and develop appropriate mitigation measures, from existing and proposed mine operations.  Particular focus was placed on the evaluation and mitigation of impacts on community water supplies through the assessment of dewatering on groundwater baseflow to the surface water system.  The model was also used to identify additional locations, to the existing surface and groundwater monitoring network, where monitoring should be conducted.

Following successful delivery of the groundwater flow model for the Yanacocha Supplemental EIA area, WMC were commissioned in 2006 to expand the model to cover the entire Yanacocha site in order to include all existing and proposed pits, heap leach pads and waste rock facilities. This site wide groundwater model, which covers an area of 300 km2, has been developed as an operational tool to help predict dewatering requirements during mine life and also to investigate impact and mitigation options both during mine life and post-closure.

In addition to the groundwater modeling studies Water Management Consultants have provided support on dewatering for Yanacocha since 1993.  This has included the system design for the dewatering of the Maqui Maqui, North Yanacocha, South Yanacocha, Carachugo and La Quinua pits.  Ongoing dewatering work includes review of existing operations at Yanacocha South, La Quinua I and La Quinua II, together with the development and supervision of investigation programs for the design of dewatering requirements for future pits eg. La Quinua III and Chaquicocha.