The Kauai County Council Planning Committee will rework a bill that calls for an update and tightening of the setback law for construction on shoreline properties.

On June 4, the committee is expected to present proposed revisions to the county’s existing law, which establishes the proximity a building can be to the shore.

Bill 2461 also aims to tie construction limits to coastal erosion data produced by the University of Hawaii.

The UH Coastal Geology Group 2010 study, "National Assessment of Shoreline Change: Historical Shoreline Change in the Hawaiian Islands," includes data from 1927 to the present pertaining to Hawaii’s three most densely populated islands: Oahu, Maui and Kauai. Geologists maintain that beaches on the three islands are eroding at an average rate of 4.8 inches a year.

The data on coastal erosion was not available when the county’s current setback law was established in 2008.

While state law requires setbacks of at least 20 feet, Kauai’s current ordinance limits the construction of structures to a minimum of 40 feet from the shoreline.

That setback is for shallow lots, less than 100 feet deep. For those with an average depth of 101 to 120 feet, the setback is 50 feet, and it is 60 feet for those with a depth of 121 to 140 feet.

Councilwoman JoAnn Yukimura, Planning Committee vice chairwoman, has proposed a number of amendments to the bill.

For lots with a depth of less than 140 feet, under Yukimura’s plan, the setback would be 40 feet plus 70 times the annual coastal erosion rate — that is, another 28 feet. An additional 20 feet is also being proposed as a safety buffer to protect properties from sea level rise, storm surges, tsunamis and other hazards.

Hanalei resident Carl Imparato told councilmembers on Wednesday that there may be loopholes in the proposed changes to the law that could enable developers to secure "exemptions" from setback limits to build closer to the shoreline. Such exemptions, Imparato said, would not protect the public’s interest and could result in "terrible visual impacts on the island."

The Council voted 6-0 Wednesday to send the bill to the committee.