With the increasing demand for clean energy, there is a growing interest in repurposing underutilized lands for solar farm developments, particularly abandoned mines, capped landfills, brownfields, and other unused areas. These locations offer a unique opportunity to transform unused spaces into sources of renewable energy, and can be particularly enticing because they are often situated near established transmission infrastructure. This makes the interconnection process simpler and more cost-effective than connecting to remote greenfield sites. In addition to contributing to the shift toward sustainable energy sources, the development of solar farms on underutilized lands can create jobs, generate revenue, and bring new life to areas that have been neglected or forgotten.

However, poor soil conditions can pose significant challenges for solar farm developers. To ensure the long-term success of solar projects, factors such as erosion control, stormwater management, and site access must be carefully considered during the design and construction phases, especially when repurposing underutilized lands for solar farm developments where the site conditions may be less than ideal.

GEOWEB® Geocells: A Versatile Site Development Solution for Solar Projects

Geosynthetics, specifically geocells, can be highly effective in mitigating the challenges posed by poor soil conditions during the development of solar farms. By reinforcing the soil and providing a stable base for access roads and balance of system (BOS) components, geocells can help distribute loads evenly and prevent soil erosion. Geocells can also be used to improve stormwater management, drainage, and filtration, ensuring that the solar farm site remains stable and functional in wet conditions.

Proper planning and execution, including the use of geosynthetics, can contribute to the long-term success of solar projects, reducing maintenance costs over time and minimizing environmental impact. In this article, we will discuss two projects that utilized the GEOWEB geocells in the development of solar farms.

Building a Solar Farm Site Access Road Using GEOWEB Geocells

Residents of Brandywine, Maryland, recognized the benefits of redeveloping a closed quarry site into a community solar farm. However, poor soil conditions made it extremely challenging for crews and machinery to access the site for construction and future maintenance.

The EPC contractor for the project contacted Presto Geosystems and local material supplier Colonial Construction Materials to devise a solution that would meet their needs. To support heavy equipment during the construction phase and to ensure the required bearing capacity for emergency vehicles in accordance with local and state regulations in the long term, they opted for the GEOWEB® Load Support System with a vegetated infill to construct a permeable access road leading to the solar farm.

With the on-site support of Colonial Construction Materials, crews deployed the GEOWEB geocells over a non-woven geotextile to construct a geosynthetic-reinforced foundation layer for the unpaved road. The geocells were then infilled with a mixture of on-site material, imported stone, and topsoil to build a vegetated roadway capable of supporting heavy vehicle loads.

The GEOWEB geocells afforded the EPC contractor and project owners the ability to beneficially reuse on-site material to reduce imported material volumes, thereby offering a significant savings to the overall project construction costs. Moreover, using a permeable access road instead of a paved road provided the added advantage of decreasing the overall impermeable surface area at the site, in turn reducing runoff and associated stormwater management requirements, and bringing even more savings in terms of both up-front and long-term operations and maintenenance costs.

GEOWEB Slope Protection System: Protecting Solar Developments Against Major Storm Events

The Spotsylvania Solar Farm, a massive 617 megawatt utility scale solar farm covering 6,350 acres, posed unique erosion protection challenges that required a permanent stabilization solution. A sloped area leading into one of the larger detention ponds on the site was experiencing severe erosion due to concentrated stormwater flows.

Following multiple unsuccessful attempts to stabilize the surface using conventional erosion and sediment control practices (including hydroseeding, sod/staples, turf reinforcement mats (TRMs), etc.), the contractor opted for the GEOWEB Slope Protection System, citing cost and performance as the major determining factors. The GEOWEB system cell walls allow water to flow throughout the system while holding the soil in place, preventing soil loss and gullies.

The GEOWEB system (mid-size cells, 6-inch depth) was successfully secured over the 2:1 slope utilizing TP-225 tendons (woven polyester, 5100 lb. break strength) anchored to a buried deadman pipe and fastened to the cell walls using the patented ATRA® Tendon Clips – which provide twice the pull-through strength of any other tendon-based load transfer device. The ATRA Tendon Clips lock into the GEOWEB cell wall for the most secure connection on the market, and together with the tendons, can be preassembled at the top of slope prior to expanding for fast and easy installation.

After installation, the slope was hydroseeded and covered with a straw-coconut erosion control blanket. The GEOWEB® 3D Slope Protection System provides a structurally stable environment for topsoil and sustainable vegetation through a structured network of interconnected cells. The 3D GEOWEB system confines and reinforces the vegetated upper soil layer, and over time, will facilitate root mat entanglement with cell wall perforations, even further increasing system resistance to erosive and sliding forces.

The 3D GEOWEB system at the Spotsylvania Solar farm has held up to multiple high-intensity rain events, including the remnants of Hurricane Ian, which impacted the region with heavy rain and storms in September of 2022. The system will continue to provide robust erosion protection against similar major storm events in the future, allowing the Spotsylvania Solar Farm to generate reliable power for the local community.

Design Support & Resources for the GEOWEB System Applications

The engineering team at Presto Geosystems works closely with engineers and project planners, offering free project planning tools and on-site support. Our recommendations will deliver a technically sound, cost-effective solution based on four decades of accredited research and testing data.