Project Overview

Full Title
Evaluation of the Impact of Biosolids Application Fields on Surface-Water Loads and Groundwater Quality in the Jordan Lake Watershed, North Carolina

Location
  Orange County

Cooperating Agencies
North Carolina Non-point Source 319 Grant Program

Project Chief
Chad Wagner

Period of Project
2011 - 2014

Team Members
Sean Egen
Kristen McSwain
Ryan Rasmussen
Steve Harden

Science Topic
Agriculture and Water Quality
Support of Federal and State Programs

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Effects of land-applied biosolids on water quality in the Jordan Lake Watershed

Project Approach

Collins Creek monitoring station downstream of OWASA biosolids
application fields at highway 54 in Orange County, North Carolina

Task 1. Collection of data to characterize groundwater, surface water and soil associated with agricultural fields with and without land applied biosolids

NCDENR installed 4 monitoring wells along the edge of biosolids application fields adjacent to Collins Creek and 2 monitoring wells along the edge of agricultural fields without biosolids applications adjacent to Cane Creek. Four rounds of groundwater samples are being collected per year during the 2-year monitoring period from each well. Samples are collected approximately every 3 months to represent seasonal differences. The groundwater samples are analyzed primarily for nutrients, total metals and fecal-coliform and E. coli bacteria; select samples are analyzed for major ions, field alkalinity and emerging contaminants. Laboratory analysis of groundwater samples will be used to examine potential groundwater transport of nutrients, metals, and fecal coliform to surface water and compare groundwater beneath fields with and without the application of biosolids.

Surface-water sampling stations will be installed at an upstream site and a downstream site on Collins Creek and at a background site on Cane Creek. Automated water-quality samplers and stage recorders are installed at each location for use in determining concentrations of nutrients, metals and fecal-coliform bacteria in a watershed receiving applications of biosolids and a background watershed with no applications of biosolids, respectively. Routine water-quality samples are collected from surface-water sites approximately every 6 weeks for the 2-year monitoring period (total of approximately 16 samples per site) as flow conditions permit. Samples at these sites are also collected during targeted stormwater-runoff events (approximately 8 per year) over the 2-year monitoring period. The Collins Creek sites will be rated to compute a continuous record of discharge for the determination of instantaneous and annual constituent loads. The sampling strategy will strive to obtain samples covering the range of streamflow conditions encountered during the study period. The surface-water samples will be analyzed primarily for nutrients, total metals, and fecal-coliform and E. coli bacteria; select samples will be analyzed for major ions and emerging contaminants.

As part of the project, laboratory analysis of biosolids source material and soil from the Collins Creek biosolids application fields will be performed to document the amounts of nutrients, metals, and fecal coliform and E. coli found in the biosolids material applied at the site. Soil samples will be collected once before and after the application of biosolids at three fields in the Collins Creek watershed each year. Two soil samples will be collected from the background agricultural field in Cane Creek each year. A total of 3 biosolids source material samples that correspond with the soil samples from biosolids application fields will be collected each year. The biosolids and soil samples will be analyzed primarily for nutrients, total metals, and fecal-coliform and E. coli bacteria.

Constituents

A broad range of constituent groups will be analyzed (table 1). Chemical analyses of water, soil and biosolids samples will be conducted at the USGS National Water Quality Laboratory (NWQL) in Denver, Colorado, the NCDENR Water Quality Laboratory and TriTest, Inc. in Raleigh, NC.

Task 2. Determine surface-water nutrient and bacteria loads in Collins Creek and Cane Creek

For all surface-water monitoring locations, the streamflow data will be combined with the sample analytical data for determining instantaneous loads of ammonia, nitrate, total nitrogen, total phosphorus, and fecal- coliform bacteria at the times samples were collected. The data from the downstream Collins Creek site and Cane Creek site will be examined to determine if a load versus flow relation can be established for use in determining annual cumulative loads of ammonia, nitrate, total nitrogen, total phosphorus, and fecal coliform bacteria in both Collins and Cane Creeks. Computations of cumulative loads would allow for a more thorough evaluation of nutrient and bacteria transport in these tributaries. Jordan Lake is 303d listed for nutrient over-enrichment and correspondingly, Collins Creek and Cane Creek are classified as Nutrient Sensitive Waters; therefore, trace metals loadings for the study sites are not a major priority for the 319 grant program and will not be computed. However, metals are of concern in biosolids (EPA, 2009; National Research Council of the National Academy of Sciences, 2002; Rudo, K., 2005) and although loadings will not be computed, metals concentrations will be used to characterize the impact of land applied biosolids on groundwater and surface water.

Analytical results for nutrients and bacteria will be compiled and coupled with streamflow data for use in determining in-stream loads with the USGS S-Plus Load Estimator (S-LOADEST; Runkel and others, 2004) program. The in-stream cumulative loads and yields at the downstream Collins Creek site and the background Cane Creek site will be compared to examine potential differences in watersheds with and without field application of biosolids. Instantaneous and cumulative loads and yields computed for the upstream Collins Creek site will be compared to corresponding loads at the downstream site to evaluate the relative nutrient and bacteria contribution of the watershed upstream of the biosolids application fields. To the extent possible, the timing of biosolids applications to fields in the Collins Creek study drainage will be documented for use in evaluating nutrient and bacteria loads.

Task 3. Perform preliminary evaluation of organic wastewater compounds as potential indicators of biosolids derived constituents in surface water and groundwater

A study by Kinney and others (2006) found that various organic wastewater compounds (OWCs) were present in nine different biosolids products produced by municipal wastewater treatment plants in seven different states. Of the 87 OWCs analyzed, 55 of the OWCs were detected in at least one biosolids product. The study indicates that additional information is warranted to better understand the potential for land applied biosolids to serve as nonpoint source of OWCs into the environment. As part of this proposed project, a preliminary round of sampling for OWCs will be conducted on biosolids source material and in groundwater at the Collins Creek application fields and surface water samples at sites, upstream and downstream on Collins Creek, of the application fields and the background site on Cane Creek. The samples will be analyzed as part of the USGS National Toxics program for a suite of OWCs, including such things as personal care products, pharmaceutical compounds, hormones, and antibiotics. The data will be examined to determine if OWCs are present in the biosolids, soils, groundwater and surface water adjacent to the biosolids application field study area on Collins Creek, and if so, can analysis of OWCs be used as potential indicator of human waste contaminants derived from residual biosolids.

Task 4. Analyze and summarize the data to characterize impact of land applied biosolids on groundwater and surface water

The water-quality laboratory results will be used to characterize groundwater and surface water in the study watersheds, with and without, land applied biosolids. Both groundwater constituent concentrations and surface-water metals concentrations and nutrient and bacteria loadings will be used in the characterization. Groundwater constituent concentrations and annual storm event surface water loads (and(or) yields) will be compared at the background and biosolids application fields sites. Concentrations and loadings in the Collins Creek and Cane Creek (background) watersheds will be compared using appropriate statistical procedures. Comparisons of upstream-to-downstream concentration and loading results in Collins Creek will be conducted using matched-pair statistical procedures, such as the Wilcoxon signed rank test and Median Aligned-Ranks ANOVA. Chemical analysis of biosolids source material and soils from fields with and without land applied biosolids will help relate the water quality results to the contributing watersheds. The data will provide insight to: 1) the differences in the amount of monitored constituents that are being delivered to groundwater and surface water from agricultural fields with and without land applied biosolids, and 2) the potential impact of land applied biosolids on water quality.