The water management plan is more complex than simply pumping...

The water management plan is more complex than simply pumping from Grants into streams. It also involves dam's with the largest being Observation Hill Dam although the day-to-day dewatering is into Mine Water Dam 1 (MWD1). As noted below in the water management plan, across Nov to March there will be excess water to release. It would therefore appear that outside that time the risk is a water shortage not excess water.


Observation Hill Dam (OHD) is also a key part of the water management system to ensure there is enough water during the dry periods. If there is someone competent running the water levels in OHD, it will be being maintained at a level that could accommodate the water currently held in Grants void after considering what can be held via MWD1 and MWD2. The 622ML capacity of OHD is going to be many times larger than the water currently in Grants pit.


So if its wet, the streams are running and Core can release excess water from site. If its dry, Core can shift water into dam's and also use it for purposes like dust suppression. As long as Core doesn't have all the dam's at max capacity at the end of the wet season they can empty Grants into one of the dam's so the more limited stream flow's during that period appears not to be an issue. At the moment it however appears convenient for Core to keep some water in the bottom of Grants. From satellite pic's the chosen water level in Grants seems pretty stable over time.

https://www.datocms-assets.com/106701/1699924760-grants-project-mining-management-plan-amendment_public-id-227052.pdf
1699924760-grants-project-mining-management-plan-amendment_public-id-227052.pdf (datocms-assets.com)

From the satellite pic below, Observation Hill dam in the bottom right much larger than the surface area of Grants.