Most grape varietals have about a 20-25 year lifespan of optimal output. Sometimes vineyards are removed earlier due to disease, such as Red Blotch, or a change in market conditions. Whichever the reason, hundreds of acres of vineyards are removed each year creating several tons of waste per acre of old vine trunks, trestles, and other materials.
The total acreage of wine grapes grown in San Luis Obispo County jumped from 9,380 in 1995 to 33,690 in 2005, the most dramatic decade of vineyard growth for the Paso Robles area. With many of the vineyards coming up on their natural useful life, redevelopment will be a big issue for Paso in the upcoming years, especially as the current groundwater restrictions limit bringing into production virgin land without an irrigation history.
Historically, growers often piled the materials together into burn piles and waited for the right weather conditions, and permits, to burn the waste. However, Air Districts all over California, including San Luis Obispo, have been limiting the number of burn days as well as increasing the cost for a burn permit due to emissions and fire risk. Growers have two main alternatives to burning the waste — grind down the waste and reincorporate back into the field (exposing the new field to pathogen risk from the prior vineyard) or haul the waste off (typically the most costly
of all options).
In discussions with Brian Maxted, CEO of the Holloway Group, he stated that his company is working on a sustainable solution he calls “Grave-to-Cradle Redevelopment.” The Holloway Group owns about 3,000 acres off Highway 46 in Lost Hills, where the company has been mining gypsum which they have been supplying to the agricultural community since 1932. All that mining has produced pits that are 50 deep and hundreds of acres wide.
“Importantly, the mine site sits on over 150 feet of an impenetrable clay basin that used to be an ancient lakebed. The same geology that allowed the gypsum deposit to form is ideal for storing waste as the clay prevents any seepage below,” Maxted said.
The group launched Holloway Environmental in 2012 and since has grown drastically reclaiming its spent mine sites with various forms of non-hazardous waste.
“Even though our natural asset is ideal for waste storage, our mission is to seek out various ways to convert the waste we take into agricultural or industrial products or as feedstock to produce green energy,” Maxted said.
In that vein, Holloway is partnering with Aries Clean Energy, a leading gasification technology provider to build a five megawatt gasification plant on Holloway’s site in Lost Hills.
“Gasification is not incineration,” Maxted said. “Organic matter, such as vineyard, orchard or other green wastes enter an oxygen-starved environment at around 1,000 degree celsius. This breaks down the organic matter into a ‘syngas’ which is used to create electricity and ‘biochar,’ a carbon rich material that is showing great promise as a soil amendment.”