Beneficial Use of Dredge Materials for Soil Reconstruction and Development of Dredge Screening Protocols

Abstract

Upland placement of dredge sediments has the potential to provide beneficial reuse of suitable sediments for agricultural uses or urban soil reconstruction. However, the use of many dredge materials is limited by contaminants, and most established screening protocols focus on limiting major contaminants such as heavy metals and polycyclic aromatic hydrocarbons and generally ignore fundamental agronomic parameters. Since 2001, we have placed over 450,000 m of Potomac River fresh water dredge materials and 250,000 m of saline materials from various locations into monitored confined upland facilities in Charles City, VA, and documented their conversion to agricultural uses. Groundwater and soil quality monitoring has indicated no adverse effects from material placement and outstanding agricultural productivity for the freshwater materials. Once placed, saline materials rapidly leach and ripen with quick declines in pH, electrical conductivity, and sodicity, but potentials for local groundwater impacts must be considered. Our experience to date indicates that the most important primary screening parameter is acid-base accounting (potential acidity or lime demand), which should become a mandatory analytical requirement. Our second level of acceptance screening is based on a combination of federal and state residual waste and soil screening standards and basic agronomic principles. High silt+clay and total organic C may also limit rapid use of many dredge materials due to extended dewatering times and physical limitations. This dredge material screening system separates potential upland placement candidates into three soil quality management categories (unsuitable, suitable, and clean fill) with differing monitoring requirements. Similar use of these sediments in urban soil reconstruction is also recommended.

Management Options for Contaminated Urban Soils to Reduce Public Exposure and Maintain Soil Health

“…If tested dredged material meets the necessary environmental standards, then it can be beneficially applied and the application's impacts can be evaluated (Darmody and Marlin, 2002; Ebbs et al, 2006; Baniulyte et al, 2009; Diaz et al, 2010). Questions remain about ensuring that suitable dredged sediment screening protocols are developed to identify when materials can be reused (Koropchak et al, 2016), and if sediments are used in soil blends, there must be adequate screening criteria for the blends.…”

Soil in the City: Sustainably Improving Urban Soils

“…Dredged material, either alone or in combination with biosolids, has been beneficially used in many remediation projects, and many impacted landscapes have been reclaimed and brought under various productive agricultural or nonagricultural uses. Koropchak et al (2016) also show that sediments may be beneficially used in agriculture and urban soil reconstruction. They note that more than 200 million m 3 of dredged material is available annually from the 40,000 km of waterways the Army Corps of Engineers maintains in the United States.…”

“…Only 30% the dredged material is beneficially used for habitat development, aquaculture, beach nourishment, recreation, agriculture, mine reclamation, shoreline stabilization, and industrial use in construction (Brandon and Price, 2007). The traditional approach has been to ignore the fundamental agronomic parameters and to look at heavy metals and polycyclic aromatic hydrocarbons concentrations in the dredged sediments as a screening tool for making decisions on beneficial use (Koropchak et al, 2016). Based on extensive monitoring and research in the past 15 yr utilizing fresh water and saline dredged sediments Koropchak et al (2016) propose that the most important primary and mandatory screening parameter should be acid‐base accounting and that an acceptable secondary screening should be based on a combination of federal and state residual waste and soil screening standards.…”

Dredged sediments contain potentially beneficial microorganisms for agriculture and little harmful cyanobacteria

“…More recently, the application of sediments removed from aquatic waterways (dredged sediments) to degraded agricultural lands has received attention for its capability to act as an organic amendment (Sigua, 2005). Such sediments have the potential to increase production in low/nonproducing areas by improving soil characteristics as a result of their high soil fertility, organic matter and water‐holding capacity (Darmody & Marlin, 2002; Koropchak et al, 2016; Sigua, 2005). These attributes can improve soil health and lead to increases in overall yield and crop production (Canet et al, 2003; Daniels et al, 2007, Darmody & Diaz, 2017).…”