ANAHEIM, Calif.–(BUSINESS WIRE)—- $WLDN–Willdan Group, Inc. (NASDAQ: WLDN) announced today that they have been selected by Encina Wastewater Authority (Encina) for a $31 million design-build contract to deliver a renewable cogeneration project. This project will use renewable biogas generated from wastewater treatment to produce on-site electricity and support resilient plant operations. This high-efficiency renewable energy system will include a new biogas conditioning system, low-emission generator