Officials with the Los Angeles Regional Water Quality Control Board are reviewing findings from RTX Corp., the owner of the former Rocketdyne site, seeking to test soil and groundwater at several businesses, homes and the Westfield Shopping Mall for contamination. The vast 47-acre property in Warner Center sits across the street from bustling Westfield Topanga Mall, and is one of the largest undeveloped sites in Los Angeles. The former Rocketdyne parcel has been undergoing an extensive cleanup to address the tainted soil and groundwater at the site that trace back to toxic chemicals produced at the site three decades ago. Cleanup of the site has been underway since 1991. Still, its contaminated groundwater has spread to the land beneath nearby homes, businesses and the busy Westfield Topanga mall, according to a report filed in June with the Los Angeles Regional Water Quality Control Board, which is overseeing the cleanup.