Dell’Osso, who is also the president of the Island Reclamation District 2062 that covers the River Islands area, said her levees meet the 200-year flood protection standard.
She said it would cost River Islands about $500,000 to prove that those levees met the requirements for the first 900 acres of the nearly 5,000-acre development. The developers will then continue the process for the rest of the project.
“We did it in 2005-2006 and the state took us out of the flood plain, and in 2009, new legislation says we must comply,” she said. “It’s massive detail, 42 things we have to check off, and we’re doing additional testing of our brand new levees.”
The Central Valley Flood Protection Plan, adopted by the state, must be incorporated into the general plans of all cities and counties in the Central Valley by July 1, 2015, according to a July 7 report to the Lathrop City Council.
The regulations began with the passing of Senate Bill 5 by California voters in 2007 that was later amended by Senate Bill 1278, the report states. The bill restricts development beyond July 1, 2016, unless permitting agencies can show adequate progress toward providing an urban level of flood protection.
“The levee is such a complicated thing,” Lathrop City Engineer Glenn Gebhardt said. “They (River Islands) do have an extensive process to prove it’s 200-year flood plain.”
Flood protection levels are classified by how often a severe flood is projected to occur. The River Islands levees must hold up to floods that statistically occur only once every two centuries.
Gebhardt said that engineering and geotechnical work would be needed to confirm all of the established criteria.
Dell’Osso said that engineers and consultants hired by River Islands would produce a report and send it to the reclamation district and Lathrop officials.
“It’s not a rubber stamp by any means,” she said. “We’re pretty confident about it. The city of Lathrop will make a determination, and we anticipate that in the next nine months.”
According to the River Islands website, residents of the community will not require flood insurance: “River Islands has protected the community with 300-foot-wide super levees that experts say can withstand 200-year flood events; therefore, this is not considered a flood zone.”
Builders expect the first residents to move into River Islands in late August.
• Contact Denise Ellen Rizzo at firstname.lastname@example.org or 830-4225.