AECOM was retained by California Water Service Company as the prime consultant to provide a design solution for a failing four million gallon prestressed concrete reservoir that was experiencing structural distress due to slope movement and expansion of the existing concrete. The final solution for the new reservoir consisted of a 50-foot-deep, buried, four million gallon structure that was constructed within the walls of the existing reservoir. AECOM’s innovative “tank within a tank” design provided the least community impact at the lowest cost. The Harris Reservoir Replacement project was completed on time, within budget and without a single interruption to service. As a further testament to the project’s success, the 18-month construction progressed without a single complaint from the neighboring community. The total cost of this project was $9.5 million, and total construction change orders were less than 0.5 percent of construction costs.