Technical Bulletin: Solar Development Risk Mitigation

Consider these USACE regulatory issues and best management practices to avoid project delays and potential violations during solar development in New York

E & E has developed this Technical Bulletin to help industry partners mitigate project risks and costly delays when plans include solar generation assets in jurisdictional wetlands.

Based on U.S. Army Corp of Engineers (USACE) New York and Buffalo District site reviews and regulatory guidance, E & E recommends the following strategies for New York solar development risk mitigation. 

The USACE New York and Buffalo Districts will not consider the installation of solar array racking support structures a discharge of fill in a wetland if there is no associated disturbance of the wetland soil profile during construction activities. This implies no surface grading for site preparation and the H-pile and/or helical screws for the racking supports/security fences, which must be installed without the excavation of a hole and/or the exhumation of any soil material from below the wetland surface. The solar array and security fence support structures cannot be back-filled with any additional material whatsoever. 

No significant disturbance of the wetland soil profile by the construction equipment used to install the support racking and solar arrays is allowed. Therefore, clients should use small scale wide tracked construction equipment that exerts minimal surface pressure while working in wetlands. Ideally, the equipment tracks will also be short, as this helps eliminate shearing forces and surface disturbance during turning. Wheeled construction equipment use in wetlands is discouraged, as it will typically do more rutting and soil disturbance than tracked equipment during the installation of solar arrays. 

Per USACE Section 404 regulatory guidelines, as soon as there is a discharge of fill into a Water of the U.S. (WOTUS) anywhere within the Project Area, the USACE is required to consider both the primary impacts (i.e. any and all discharge(s)) plus any potential secondary impacts related to the single and complete project (e.g. shading, drip line erosion, or long-term maintenance of any solar arrays sited within the wetland). As such, extensive siting of solar arrays within wetlands does carry project specific risk and could potentially translate to wetland impacts depending on the project and site circumstances. Permanent wetland impacts greater than 0.1 acres and up to 0.49 acres associated with a NWP51 or NWP12 will require a pre-construction notification (PCN) and may be required to mitigate the impacts by the District Engineer. If the project’s permanent wetland impact exceeds 0.5 acres, then the requirement for a Section 404 Individual Permit (IP) arises. However, if all permanent wetland impacts in the Project Area remain under the 0.5 acre threshold (and/or 300ft of stream bed) associated with a Nationwide Permit  51 and/or NWP12, then the project can avoid the additional permitting requirements, time, and costs associated with a Section 404 Individual Permit (IP) application. Proper selection of the Project Area to avoid and minimize wetland impacts and to adhere to NWP51/NWP12 impact thresholds is a useful strategy to reduce permitting review and project development risk. 

For more information on solar development risk mitigation, contact E & E’s Chief Environmental Scientist Jeff Mason at or 716-462-2543.

Solar Racking and Panel Array Siting and Installation BMP’s in Wetlands 

In instances where wetlands cannot be avoided, it is best to site panel arrays and project infrastructure in the Project Area to minimize impacts to wetlands to the extent practicable and to target the driest areas possible within a wetland feature during the project design phase. Areas within wetlands with tussock sedge, pit and mound microtopographic relief, and standing water are excessively risky for construction activities and could lead to a discharge of fill event, and/or triggers a violation during construction. Installation of racking support structures and panels arrays in wetlands should be targeted to when the ground is driest and/or frozen, generally the late summer months and/or mid-January to late February respectively, depending on the location and the weather conditions. While many wetlands never completely dry out in the summer or freeze in the winter, these are generally agreed upon as the best windows of time in New York to install solar equipment inside a wetland. 

It has been recently advised that the use of construction matting within wetlands in both the New York USACE District and Buffalo District will not be considered “fill” material and/or a permanent impact if the construction matting is entirely removed after construction and/or maintenance activities are completed. Agency coordination regarding the use of construction matting in wetlands is recommended as a topic of discussion during USACE pre-application meetings for each individual project. 

Mitigate the Risk of a Section 404 Violation During Construction 

Having Environmental Inspectors (EI’s) on site during construction is an efficient way to mitigate some risk during construction activities, especially for projects with panels sited in USACE jurisdictional wetlands. In these circumstances, the stakes are quite high. If more than a ‘de minimis’ amount of soil disturbance triggers a discharge of fill event, then the USACE will consider this a violation, and a cease and desist order for construction is probable. Once a violation occurs, then the project is likely to be in trouble moving forward, as it will be subject to site inspections from the USACE – and likely the NYSDEC – potential daily fines of up to $50,000 a day, construction delays, and possibly the need to conduct compensatory mitigation. The USACE does not have the legal authority to regulate or stop a project until a discharge of fill occurs, so the need to adhere to a specified design, construction techniques, and best management practices (BMP’s) is paramount for project development success when siting solar arrays in USACE regulated wetlands is unavoidable. 

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