June 14, 2022

Dirt Lockers: Stop Erosion, Save Water and Recycle Plastic while Growing Trees with One Solution,
14 June 2022


With beads of sweat running down his face under the hot Southern California sun, Mark Trebilcock struggled with the hard-packed clay soil and uneven slope on his hillside. No matter what he did to grow the fruit trees and plants he wanted, the only thing growing in his yard were weeds and his aggravation.

The soil erosion and inability to keep water at the roots were the main culprits. He had tried multiple store-bought products to mitigate the erosion and keep the plants hydrated, but nothing worked until he created a prototype in his garage that he began to test out on his yard. His prototype was the first version of the Dirt Locker®, a hillside terracing device that saved water and stopped the persistent erosion.

The Dirt Locker® can also reduce agricultural waste, plant mortality, labor for terracing or maintenance, and consumes waste plastics through recycling.

When traveling in East Africa Mark saw the need for an agricultural product to help people grow their food in inhospitable terrain. During his trip through Rwanda and Uganda, Mark began to seriously consider the possibility of developing an international network for the Dirt Locker®, knowing that it could help mitigate problems like plastic pollution, land availability, and unsustainable agriculture.

He learned that in Rwandan culture, it is customary for families to subdivide the property to the children, generation after generation, inevitably leading to less land to a farm which creates a food problem when they are not able to grow enough to feed their families. In addition to the overpopulated land, non-farmable slopes, and erosion deteriorating the little remaining land, Rwanda has become dependent on outside sources for food instead. He saw an even more dire situation when he went to Haiti as a volunteer of Love A Child (

This organization has provided help to Haitians in job creation, healthcare, orphanage services, and teaching them agricultural methods. Sadly, deforestation appeared to be the root of many of the island’s issues, which have reduced rainforests to deserts, preventing life on land. Consequently, the soil runoff has also negatively impacted aquatic life. Early in the process development phase, Mark sent several DirtLocker kits to Haiti. There is a hope that they may be part of the revegetation solution for this impoverished nation once deployed. The comments and feedback from expert landscapers bolstered his confidence to move forward. It seemed like a no-brainer that a product that converts non-arable land into a productive growing environment using scrap plastic had a commercial market. Over the years, Mark continued to tinker and improve the design. He had an opportunity to work on the product full time. He knew this was his opportunity to commercialize the Dirt Locker®. Mark created a new configuration of the Dirt Lockers® where the pieces could be connected into a network that could be folded flat for ease of transportation and storage. The folded units can be pulled up onto a hillside and expanded out like an accordion. The expanded network is a collection of cells, where each cell is a flat terraced growing area used for growing plants or walking/maintenance access on the hillside once backfilled with soil. The newly formed matrix of terraced cells created by the expanded Dirt Locker® system significantly reduces erosion by retaining water on the hillside for the plants while also maintaining the topsoil.

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This network of basins acts like a gravity-fed water filtration system that holds the soil while allowing excess water to cascade over to the next cell. The arrangement solves multiple environmental issues such as soil erosion, water use, rainfall/ agricultural runoff, the high mortality rate for plants on hillsides, and pollution since they are 100% recycled plastic. Finally, the connecting hardware was eliminated, further simplifying the assembly/installation process. Raised in Miami, Florida as a teenager, Mark had a passion for gardening and growing food primarily due to his mother’s love for the same and her interest in unique fruit trees. His interest led him to start a small landscaping business although he had to transport his equipment by bicycle, sometimes miles away.

The logistical obstacles he overcame as a young entrepreneur motivated him to conceive and implement product/ process improvements. It seemed natural to pursue a degree in Industrial Engineering and Management Systems from the University of Central Florida. Mark maintained his love of landscaping throughout the years, always trying to find solutions to gardening problems. He eventually left the flatlands of Florida and moved to California, where he continued pursuing his passion for gardening and his career in manufacturing excellence for medical devices.

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Mark’s passion for horticulture and landscaping hit a wall when attempting to grow on the arid, clay slopes of Southern California. It became clear that many people, homeowner associations, farmers, and gardening enthusiasts struggled to produce on slopes. The creative problem-solving methods Mark developed that generated production efficiencies during his years in the telecom, medical device and biopharma industries were employed when Mark was learning how to grow in the mountainous, water-starved, hardpacked rocky clay soil in Southern California.

The current Dirt Locker® was born after several iterations on that original prototype, and years of evaluating materials, testing, trial, and error. After his experiences internationally, it became vitally important to Mark that the Dirt Locker® was developed so that it requires no special hardware, tools, or skills to assemble and/or install.

The product was developed so that the pieces can connect manually with no additional proprietary hardware. Additionally, regardless of its configuration, there is only one SKU in each assembly. Whether the product is assembled into a network of hundreds of pieces or a ring for an individual plant, only one SKU is used. The only hardware used with the Dirt Locker are commercially available or easily fabricated rebar J-hooks for securing the network to the hillside during installation. The only tools required for installation are common to any landscape project. →

Dirt locker

→ In addition to the simple assembly process, the Dirt Locker® is environmentally beneficial and safe to work around. The Dirt Locker® is ecologically friendly in several ways, but at its core is constructed from 100% recycled, post-consumer waste, high-density polyethylene (HDPE). The Dirt Locker® is also food-friendly because HDPE is one of the few plastics approved by the FDA for food storage and preparation. As an example of the positive environmental impact, each Dirt Locker® saves on average the equivalent of 13 milk jugs from the landfill or oceans. In addition, the Dirt Locker® helps recover nearly 100,000 milk jugs monthly. The recycled plastic used in the fabrication of the Dirt Locker only adds to the environmental benefits while in use. The overall efficiencies to the end-user are that the product does not require any special training, tools, or skills to use. Those efficiencies can help the user convert otherwise non-arable sloped terrain into terraced and agriculturally productive hillsides. In addition, the Dirt Locker® does not need the same labor intensity, infrastructure, or cost to install than traditional terracing methods require. Having developed a product easy to manufacture and assemble, Mark was ready to launch the Dirt Locker® commercially in 2018. The product’s demand has grown exponentially, even though marketing is limited to YouTube videos, the website, Facebook groups, and word of mouth. Our customers have consistently bestowed generous compliments on the product and sales team. In addition, customers routinely comment on the ability of the Dirt Locker® to support the growth of plants in areas where they had previously been unsuccessful. Here are a few of the comments:

Bob B. Thousand Oaks CA: The product saved me 70% on my project over traditional solutions and looks better and will save water and plants. Adam MD. North Carolina: Everyone in the neighbourhood thinks the lockers are brilliant. Thanks for all of your help! Srinivas, Georgia: Thank you so much for the detailed response, the wonderful invention, and the service. Gillian, Canada: I LOVE this product. Deborah, Puerto Rico: We will be planting more coffee plants inside of the next set of some Dirt Lockers®. Dan G. Fallbrook CA: I came across your product, and it is exactly what I need! As demand for Dirt Lockers® grew throughout the United States and internationally, the machine used to manufacture the Dirt Locker® in Mark’s garage could not keep up. So Mark expanded his manufacturing capacity by reaching out to his plastics supplier. They had the experience and manufacturing capacity to keep up with demand. They also had the experience with the plastic so there would be no learning curve. Outsourcing manufacturing of the Dirt Locker® proved there are new prospects for the product, including manufacturing the product closer to the point of use, thus reducing carbon footprint through transportation efficiencies. The Dirt Locker® went from concept to reality first with a scaled-down version using a 3D printer with the help of an online CAD program that allowed the interlocking terrace concept validation on a small scale. The scale models demonstrated the effectiveness of the Dirt Locker®, enhancing Mark’s conviction to create a fixture used with hand tools to fabricate the first functional full-scale units. The assembled “handmade” units made networks at his house in California and at his mother’s residence in Florida. These initial installations proved that the product was beneficial and worked as expected. The first large Dirt Locker® project made from 300 Dirt Lockers® was pulled onto a hillside and backfilled with soil in one day. Mark enlisted the help of a local landscape company and entrepreneur and filmmaker Jon Schneider who created multiple videos of the entire installation and a local landscape company. Jon has since created a library of YouTube videos used for demonstrating the capabilities of the system and as instructional aids for the Do-It-Yourself installer. The five workers quickly assembled most of the 300 units in about 45 minutes after only 15 minutes of instruction. The completed web of DirtLockers initially folded neatly on the sidewalk at the bottom of the hill was quickly expanded up the slope until it covered the face of the hillside. Next, the crew began attaching the final pieces where the contour of the hillside warranted, and before lunch, the network of cells was getting backfilled with improved soil. With the cells filled, the individual terraces could now be safely traversed by workers, facilitating the planting process.

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The benefits of hillside access using the Dirt Lockers is both demonstrated and succinctly stated in the testimonial by customer Stormy C. on the Dirt Locker® YouTube channel. “Something that the retention wall doesn’t have is steps with an option to walk up and have to access the plants. You are still going to have weeds and overgrowth that need to be maintained.” Stormy C. CA Once planted, the Dirt Locker® terraced hillside flourished. Approximately six months after planting the hillside, Mark’s neighbors, recalling the bleached lifeless slope, now commented on how much they appreciated its beauty and the enjoyment it brought to their daily walks. During the summer, when temperatures are frequently triple digits, the containment properties of the Dirt Locker® allowed water to penetrate deeper into the hillside, which helped the soil stay hydrated longer.

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The enhanced soil hydration encouraged the plants to flourish, improving the strength and stability of the slope with time, this was stated most poignantly by customer Karl B. of New York below. “A standard retaining wall is the strongest it will ever be on the first day that it is completed, whereas the Dirt Locker® system gets stronger over time as the plants root into the dirt which is what makes it strong. It’s a complete eco-system of plantings nd the Dirt Locker system that work together to hold back the hill.” Karl B., NY Mark worked tirelessly in all Dirt Locker’s® design, testing, installation, and manufacturing phases until he was ready to share it with the world. His brother Norman, the owner of Trebilcock Consulting Solutions (TCS), a civil engineering firm in Naples, Florida ( ), had some of his engineers help Mark with drawings and product evaluation. While developing the Dirt Locker® using different manufacturing methods, it was always evaluated for manufacturing in areas with the same availability to technology or skilled workers. For instance, in some geographies, complex machinery may not be realistic.

However, a fixture and hand router are possible, especially when the pay rates permit labour-intensive industries allowing Dirt Locker® to move manufacturing to new regions where it makes economic sense. We have only begun to realize all the benefits of this disruptive technology yet an easily applied product. Our objective is to work with professionals globally to find other uses, benefits, and potential enhancements to the Dirt Locker®