20220233 SSUUSTSTAAINAINABBILITILITY REY REPPORORTT Treating process water for beneficial reuse on the Gross Reservoir Expansion Project On the Gross Reservoir Expansion Project, Kiewit Barnard The process water is directed down the dam's face to a Message from Management JV is raising the height of Denver Water’s Gross Reservoir water catch basin behind a cut-o昀昀 wall. The water is then Dam by 131 feet, taking it from an existing height of 340 feet pumped from the basin to treatment tanks, where the pH 1. Overview to a new height of 471 feet. This will increase the storage of level and turbidity are adjusted and filtered as needed. the reservoir from 42,000 to 119,000 acre-feet. Then, the treated water is pumped from the treatment About Kiewit tanks to an onsite water tower for dust control use. Sustainability at Kiewit Two operations on the project generated large quantities Our Projects of process water – hydrodemolition and wire saw cutting. Over the course of two years, 4.6 million gallons of water was treated and reused on site, with a peak treatment of ■ Hydrodemolition is a concrete removal technique 60,000 gallons of water per shift. 2. Governance using high-pressure water to remove deteriorated Corporate Governance and sound concrete as well as asphalt and grout. The alternative to the Beneficial Use Permit allowing Supply Chain At Gross Reservoir, a hydrodemolition subcontractor the process water to be treated for dust control use, removed an average of 2-3” of depth of concrete would’ve been to truck water to an o昀昀-site treatment 3. Environmental from the face of the dam. This was necessary to facility. This alternative would have increased tra昀昀ic in ensure that roller compacted concrete (RCC) – which the canyon, leading to increased emissions and increased Environmental Stewardship will be used to raise the dam – will bond to the face safety concerns. Greenhouse Gases & of the existing dam. Energy Consumption ■ Diamond wire sawing is a sawing method used in complex construction and demolition projects. On this 4. Social project, wire saws were used to remove concrete from 4.6 MILLION Health & Safety the existing ogee at the top of the dam. This required GALLONS OF WATER Diversity, Equity & Inclusion more than 14,000 square feet of cutting to remove TREATED FOR REUSE ON SITE Talent & Workforce nearly 100 pieces of block from a 350 cubic yard mass. MINIMIZING TRUCK TRAFFIC, Development Working closely with Colorado Department of Public Health EMISSIONS AND SAFETY CONCERNS Community Engagement & Environment (CDPHE) and Boulder County, the team developed a cohesive plan to collect and treat the process Appendix water used for these operations. This included getting a Beneficial Use Permit from CDPHE. Stakeholders worked together to determine the relevant parameters for testing, treatment, record keeping and reporting. 3636