Is Compost Quality Important? Research on the Performance of Compliance Vs Non-Compliance of Federal Specifications for E&sc Compost-Based BMPs.

Compost-based best management practices (BMPs) used for erosion and sediment control (E&SC) have become widely accepted over the past 10 years. Currently, over 40 state departments of transportation or environmental protection agencies have approved specifications for compost blankets and compost filter socks.  Additionally, the US Environmental Protection Agency (EPA), USDA Natural Resource Conservation Service (NRCS), US Army Corp of Engineers (ACE), and the American Association of State Highway Transportation Officials (AASHTO), have all published specifications and guidance documents for the use and application of these practices.  Adoption has been spurred by the interest in utilizing practices made from sustainable and locally available materials, and recent published scientific research indicating the high performance of these BMPs. While detailed specifications on compost characteristics and quality exist at the state and federal level, often these specifications are not adhered to in the field.  And while ‘compost’ is widely recognized material by the general public, the particular specifications required for compost blankets and compost filter socks are not widely understood.  Recent research has shown the difference in performance between following state and federal specifications, versus not, for these practices is incredibly large.  For example, university research has shown compost that did not adhere to compost blanket specifications for particle size distribution (but resembles compost typically utilized in commercial agriculture, garden, and soil blending applications) increased total sediment (TS), total suspended solids (TSS), and turbidity (NTUs) by 4 times, 5 times, and 8 times, respectively, relative to compost media that met federal specifications.  Similarly, organic materials that are not sufficiently composted, thereby not adhering to biological stability and maturity standards, often have nutrients that are not stable, and can be transported in stormwater runoff in loads similar to commercial fertilizer applications.  Similarly, compost media used in compost filter socks and filter berms, must meet a particle size distribution specification, otherwise the BMP will act as a solid barrier rather than a passive biofilter, thereby significantly reducing its filtration capability and runoff storage capacity. Reduced runoff storage capacity, leads to increased overtopping, or decreased design and installation spacing requirements on slopes.  Recent large scale ASTM testing of compost socks utilizing commonly used filter media - but too fine to meet state and federal particle size specifications - compared to filter media that complies with specifications, revealed a 30% decrease in sediment removal efficiency and P Factor, and 12 times more tons/acre of sediment loss.  This presentation will focus on federally published public agency specifications (USEPA, USDA NRCS, US ACE, AASHTO) for compost blankets and compost filter socks, and corresponding research performance data on how these practices perform when specifications are followed versus common specification non-compliance in the field.