Carollo Engineers Inc.

Carollo Engineers Inc., headquartered in Walnut Creek, California, delivers water and wastewater treatment engineering, environmental consulting, and research and development services to federal agencies as a prime contractor (77% of recent awards) and as a subcontractor on environmental and defense infrastructure programs. The firm operates full-and-open, competing without set-aside designations across its federal footprint.

Carollo's customer concentration is split between civilian infrastructure and energy agencies. The top five funding sources account for 65% of awards by count: the Department of the Interior Bureau of Reclamation (8 awards, $2.5 million combined potential value), the Department of the Army Corps of Engineers (5 awards, $5 million), the Environmental Protection Agency Office for Water (3 awards), the Department of the Treasury United States Mint (2 awards, $5.8 million), and the Department of Energy Office of Energy Efficiency and Renewable Energy (2 awards). However, the potential-value ranking surfaces the U.S. Mint and the Indian Health Service as dollar anchors: the Mint holds $5.8 million across two awards (including a $4 million single-award Indefinite Delivery Contract for design and installation of a wastewater treatment plant at the Denver Mint facility, with a $1.8 million delivery order issued in September 2024 for the DN Wastewater Treatment Plant in Walnut Creek), and the Indian Health Service carries $5 million in one award. Carollo's parent-vehicle footprint is lightweight—four task orders total across multiple IDCs and a GSA Multiple Award Schedule—indicating most work flows through direct awards or agency-specific contracts rather than governmentwide vehicles.

Recent prime awards include a $2.42 million Cooperative Agreement from the Advanced Research Projects Agency-Energy (ARPA-E, CFDA 81.135) awarded May 7, 2026 under the RECOVER (Realize Energy-rich Compound Opportunities Valorizing Extraction from Refuse Waters) program (DE-FOA-0003510, Control Number 3510-1660) to develop selective recovery of critical metals from produced water using engineered ferritin protein nanocages, with completion targeted for May 6, 2029 at the firm's Walnut Creek facility. Carollo is also a Cooperative Agreement recipient from the Bureau of Reclamation on multiple water-reuse and treatment initiatives: a $1 million agreement awarded August 24, 2023 for testing in-situ resin regeneration using bicarbonate for potable water reuse (completing March 31, 2025); a July 25, 2023 agreement to pilot a novel wastewater treatment configuration for groundwater recharge incorporating microfiltration, closed-circuit reverse osmosis, and microbial fuel cell technology in partnership with Eastern Municipal Water District, Cal Poly Pomona, DuPont, and Aquacycl (completing March 31, 2025); a September 7, 2022 agreement on reverse osmosis-based water reuse fault detection using machine learning and model predictive control (completing September 30, 2026); and earlier agreements on biological selenium removal from agricultural drainage water and aeration energy optimization in water resource recovery facilities. Carollo also holds a cooperative agreement from the Office of Energy Efficiency and Renewable Energy on mainstream aerobic wastewater treatment using process-produced hydrogen peroxide (awarded October 1, 2023, completing October 2, 2025).

Award activity has been episodic—two awards in 2021, one in 2022, four in 2023, six in 2024, and three in the first five months of 2026—with combined potential value of $21.8 million and combined obligated dollars of $34.8 million. Only one award reaches ultimate completion inside the next twenty-four months, creating minimal near-term recompete exposure. In its subcontractor role, Carollo provides environmental consulting and engineering planning assessment to Eastern Research Group Inc. on EPA water technical assistance and wastewater access-gap programs (community engagement and drinking water, wastewater, and stormwater project support); environmental consulting services under a U.S. EPA National Drinking Water Program contract; and technical support to Consolidated Nuclear Security, LLC on management and operating contracts for the Y-12 National Security Complex and Pantex Plant. Top NAICS categories reflect the engineering and environmental profile: Engineering Services (8 awards), Environmental Consulting Services (3 awards), and Facilities Support Services (3 awards). Service Contract Inventory data shows minimal SCI-reportable activity—only two records in FY2024, both as named subcontractor, yielding 0.8 FTEs—indicating that Carollo's federal work flows primarily through grants, delivery orders, and fixed-price engineering contracts rather than labor-hour or time-and-materials service contracts.