Born in Plaquemine, Louisiana, Cashio received his B.S.L.A. from Louisiana State University in 1966. He then worked for Simonds and Simonds in Pittsburgh before moving to New Orleans in the late 1960s, where he would practice for the rest of his life. In 1968, he formed Cashio Cochran Sullivan, which soon became the landscape architecture firm of Cashio Cochran, a partnership with Jack Cochran that would last for 42 years. With the addition of Leonard Torre in the 1980s, the firm was renamed Cashio, Cochran, Torre / Design Consortium (eventually Torre Design Consortium).
In the early 1970s, Cashio renovated Jackson Square in the city’s famous Vieux Carré, converting the surrounding streets to paved pedestrian zones. He also developed the plan for the nearby Moon Walk and Woldenberg Riverfront Park. He worked on the city’s Louis Armstrong Park and the Audubon Park Golf Course, and, after Hurricane Katrina, created the master plan for the renewal of City Park. Cashio was the landscape architect for the 1984 Louisiana World Exposition. A registered architect and landscape architect, he served as the president of the Louisiana Chapter of the American Society of Landscape Architects (ASLA) and as the vice president of the New Orleans Chapter of the American Institute of Architects. The firm’s work along the riverfront near the Vieux Carré won an Honor Award in the Design category from the ASLA in 1981, and the Louisiana Swamp Exhibit at the Audubon Park and Zoological Garden won a Merit Award in Design in 1985. Cashio became a Fellow of the ASLA in 1998. He died in New Orleans of pancreatic cancer at the age of 68.