Central Maui’s inland sand in decline
Off-island exports have fallen since 2006, report says
Nearly 2 million tons of sand have been removed from Central Maui since 2006, leaving it either depleted or very soon to be depleted and unable to replenish the island’s beaches that need some 158,000 tons of sand, according to a new study released Tuesday on sand availability in the county.
Department of Public Works Director David Goode released the study, which served as an update to a 2006 study, and sent a letter to Council Member Elle Cochran recommending that sand not be exported off-island. He added that the sand could be excavated and stockpiled in the county to benefit Maui residents, as long as the removal is not detrimental to cultural artifacts.
“As in 2006, the situation today is that we will someday relatively soon run out of inland sand to use for a variety of uses, including concrete manufacturing, bedding for pipes, beach replenishment, volleyball courts, sandbags for flood protection, etc.,” Goode wrote in the letter. “The 2018 study notes that sand is being imported from places such as British Columbia, or substituted with other materials for use in concrete products, which adds cost, time, uncertainty, and could be adding our carbon footprint.”
The 30-page study prepared by SSFM International Inc. was originally requested by Mayor Alan Arakawa and subsequently the County Council in response to concerns about a contractor removing and shipping truckloads of sand to Oahu from a Maui Lani housing project in 2017. The practice was captured by a Honolulu TV news station, and the contractor soon stopped sand mining at the site.
A six-month temporary moratorium on sand mining was passed in January and later extended until the end of the year to give the county time to complete the study and possibly pass new laws. Arakawa had originally requested studies on Maui’s sand resources in 2003 and had asked the council to consider a moratorium on exports after the 2006 report.
As recently as the 1970s, sand from Central Maui was a “relatively easy commodity to attain,” according to the new study. Thousands of years of trade winds helped form vast inland sand dunes considered “a unique geological feature” within Maui.
“Maui’s inland sand has long been a key ingredient for high quality concrete and generally meets the highest quality standards for sand used in concrete production,” the study reads. “This sand resource, based on lab testing, was found to produce a high quality concrete product because the natural sand particles are very smooth and round in shape. These qualities made the concrete produced with Maui sand desirable among the construction and concrete production industry.
“This sand resource is also an important natural commodity that is desired for dune restoration, beach nourishment and emergency coastal management responses on Maui since it is carbonate beach sand of local origin.”
Sand mining first ramped up in the 1980s and vaulted Maui as the primary source of sand used in Honolulu concrete. By 2006, 70 percent of the island’s sand stock had been shipped to Oahu.
About 720,000 tons of sand was mined on Maui from 1956 to 1985, with just 50,000 tons sent to Honolulu, according to the study. In the following decade from 1986 to 1995, 1.8 million of the 2.5 million tons of sand removed was sent to the state capital.
Honolulu exports increased to 2.2 million tons of the 3 million total from 1996 to 2005, but fell to 1.7 million of a total 2.3 million tons after 2006. In total, over 9 million tons of sand have been removed from the Valley Isle in the past 60 years, with the vast majority originating from Central Maui.
Today, most of Central Maui’s remaining inland sand dunes are unavailable for excavation due to existing development that covers the underlying sand dunes and archaeological and cultural protections that prevent ground disturbance.
County officials anticipate nearly all future beach replenishment projects to use offshore sand due to the lack of availability of high-quality inland sand. The report expects demand for beach replenishment to increase in the future with rising sea-levels and recommended the county stockpile high-grade inland sand, excavate or purchase lands that have remaining sand stock.
Over the last 12 years, an estimated 1.3 million tons of sand have been removed from Central Maui sand dunes, according to the study. Another 451,000 tons of sand also have been removed from a parcel owned by Alexander & Baldwin, located south of the Maui Lani project and bordered by Kuihelani Highway and Waiko Road.
The combined 1.8 million tons of sand removed comes close to the 2006 study’s total sand inventory of 1.95 million tons in the Central Maui area. The old study originally projected the sand to run out in five to seven years based on usage rates by the island’s two major concrete and aggregate suppliers: Hawaiian Cement and Honolulu Construction & Draying.
The number of barge departures has decreased steadily since 2006 because the two concrete companies began reducing their reliance on Maui sand and sought alternative sources, according to the 2018 study.
By August 2007, Hawaiian Cement had phased out of exporting sand to Oahu and instead began importing sand from Canada to send to Honolulu. The company estimates it is importing 50,000 tons of sand from Canada, two to three times annually, which supplements sand aggregate generated at its Hawaii quarries for concrete production.
HC&D, formerly Ameron Hawaii, continued exporting sand from 2006 to 2017, but was forced to stop with January’s moratorium. Based on state Department of Transportation sand aggregate barge totals, just 12 sand barges left Maui for Oahu between October 2017 and May 2018, “indicating a significant decrease in the frequency of sand barge departures,” according to the report.
Also included in the new report is an expanded scope over the old one to include Qdo soils, which are defined as older dune deposits only found in Central Maui. U.S. Geological Survey maps showed about 1,800 acres underdeveloped and potentially having sand available, though estimates range widely from 3.2 million tons to 650,000 tons.
“There remains a high degree of variability in the amount of sand available, not only due to depth of sand and the quality of the sand, but also the likelihood of encountering iwi kupuna (ancestral bones) and other cultural artifacts,” Goode wrote in his letter.
The sand dunes contain historical, archaeological and cultural resources that are protected under federal and state laws. More than 60 Native Hawaiian burials have been discovered from one site in the study.
* Chris Sugidono can be reached at email@example.com.