Measuring and Removing Dissolved Metals from Stormwater in Highly Urbanized Areas (2014) / Chapter Skim
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A-1 A P P E N D I X A Practical Guidance for Measurement of Dissolved Metals in Stormwater Runoff
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A-2 T A B L E O F C O N T E N T S A-3 Chapter 1 Introduction A-4 1.1 The Issues A-8 Chapter 2 Preparation and Planning A-10 Chapter 3 Constituent Selection A-10 3.1 Conventional Parameters A-11 3.2 Major Ions A-11 3.3 Organic Composition A-12 Chapter 4 Equipment A-14 4.1 Sampler Intake Strainer, Intake Tubing and Flexible Pump Tubing A-15 4.2 Composite Containers A-16 4.3 Flow Monitoring A-17 4.4 Rainfall Gauges A-17 4.5 In Situ Sensors A-17 4.6 Power A-17 4.7 Telecommunication for System Command/Control and Data Access A-18 Chapter 5 Sample Collection and Handling Procedures A-19 5.1 Pacing the Sampler A-20 5.2 Percent Capture A-21 5.3 Peak Capture A-21 5.4 Evaluation of Representative Sampling A-22 5.5 Sample Splitting A-24 5.6 Filtration Issues A-25 5.6.1 Filtration Methods A-27 5.6.2 Real-time Filtration A-29 Chapter 6 Analytical Methods and Quality Assurance/Quality Control A-29 6.1 Detection Limits, Data Quality Objectives, and Measurement Quality Objectives A-30 6.2 Precision, Bias, Accuracy, Representativeness, Completeness, and Comparability A-30 6.2.1 Precision A-30 6.2.2 Bias A-31 6.2.3 Accuracy A-32 6.2.4 Representativeness, Comparability, and Completeness A-34 6.3 Laboratory Quality Assurance/Quality Control A-34 6.4 Field QA/QC A-34 6.4.1 Blanks A-35 6.4.2 Field Duplicates A-36 Chapter 7 Equipment Cleaning, Blanking, and Tracking A-37 7.1 Laboratory Sample Bottles A-38 Chapter 8 Reporting and Documentation A-40 Bibliography
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A-3 One major challenge associated with characterization of receiving waters and stormwater runoff, as well as assessment of BMP effectiveness are the low concentrations that must be achieved to meet water quality standards (Table 1)
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A-4 number of other resources have been developed in recent years that contain useful information for planning and implementing stormwater monitoring efforts that focus on dissolved metals at concentrations relevant to water quality criteria. Many of the more valuable guidance documents and areas addressed by these documents are summarized in Table 2.
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A-5 Table 2. Summary of key resources for the design and implementation of a sampling program for dissolved metals at low levels.
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A-6 with sampling, processing, and analyzing dissolved metals in highway and urban runoff. Runoff from highly impervious pavements and roadways transports dissolved, colloidal, and suspended solids in a heterogeneous mixture and, along with pH, alkalinity, traffic levels, and residence time, influences the partitioning of heavy metals.
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A-7 using filtration pore size to distinguish between particulate and dissolved metal species, monitoring typically requires assessment of dissolved metals since they serve as the basis for both interpretation of biological effects and current water quality criteria. It becomes more important to standardize and document the actual filtration techniques used as well as control factors such as filter packing, which is known to increase variability.
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A-8 Preparation and Planning Developing a stormwater monitoring program that is capable of obtaining environmental data that are representative, accurate, and provide the supporting information needed to be used by other programs requires careful preparation and planning. A monitoring program designed to obtain environmental data for decision making purposes should be conducted in three phases: planning, implementation, and assessment.
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A-9 SAMPLING AND ANALYSIS PLAN 1.0 PROJECT OVERVIEW/DESCRIPTION 1.1 Description of why the project is being conducted 1.2 Description of who is conducting the project 1.3 General scope of monitoring activities 1.4 Project organization/roles and responsibilities 2.0 MONITORING SITE(S) 2.1 Site location (map)
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A-10 Constituent Selection A substantial amount of research has been conducted on the characterization, speciation, and removal of dissolved metals in highway runoff. This research has demonstrated that metal partitioning between the dissolved and particulate-bound fractions in stormwater is a dynamic process that is influenced by a number of different factors (Doner 1978; Bauske and Goetz 1993; Granato, Church, and Stone 1995; Breault et al.
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A-11 Temperature can be an important factor especially in regions that receive summer storm events and where thermal effects are important to measure. Temperature can also be important when using a geochemical model to determine speciation of dissolved metals.
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A-12 C h A P T E r 4 This guidance is based on use of automated stormwater monitoring equipment to collect flow-weighted composite samples of runoff for analysis of dissolved metals at levels relevant to receiving water quality criteria. Stormwater monitoring systems are commercially available from several sources.
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A-13 Construction material for sampling equipment (does not apply to well casing) Target analyte(s)
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A-14 • Sample line velocities that decrease with head differentials (ability to meet minimum recommended line velocity of 2.0 ft/s diminishes) without the use of auxiliary pumps • 100-foot line limitation • Sample volume repeatability Most of these limitations can be minimized by incorporation of these considerations in the site selection process and when installing the equipment.
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A-15 1999; Smith and Granato 2010)
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A-16 of one Teflon® stopper should be available for each monitoring site during storm events. Each field sampling crew should have additional stoppers with holes ("sampling stopper")
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A-17 4.4 Rainfall Gauges Installation of electronic tipping bucket rain gauges is highly recommended for monitoring of smaller drainages. Use of a localized rain gauge provides better representation of conditions at the site.
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A-18 Sample Collection and Handling Procedures Monitoring stations typically include a flow monitoring component that incorporates instrumentation and software for measuring and recording flow. The flow meters are comprised of a datalogger/control module to allow storage and processing of the flow data and communication with a composite sampling device.
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A-19 at very high rates for brief periods of time. More frequently, aliquot volumes are set around 500 ml.
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A-20 Ts = Maximum time (minutes) for sampler to go through the full sampling cycle.
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A-21 from predicted rainfall. Minimizing these losses requires the ability to remotely monitor progress at the site so that sampling crews can be alerted and directed to the site before the last aliquot is pumped.
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A-22 is limited. Strecker, Mayo et al.
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A-23 (Based upon and modified from USGS NFM Table 2-6) Splitter Advantages Limitations Fluoropolymer churn splitter Suitable for both inorganic and non-volatile organic analyses.
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A-24 of churns and cone splitters are well described in the USGS National Field Manual (various dates)
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A-25 of different filter types, pore sizes, filter surface areas, and methods of filtration. They also demonstrated how filter packing could alter the size classes of sediment that pass through the filter.
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A-26 a mobile laboratory or walk-in shelter that provides a clean, dry, and well lit location for handling the samples. Use of a glovebox is recommended for maintaining clean conditions.
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A-27 10. DH starts the pump and the remaining sample is processed through the filter and collected in the sample bottle (final volume 500 mL)
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A-28 be required to construct the sampling capsule from appropriate materials. A small, inline capsule could be used to trap a small quantity (~20ml)
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A-29 The sampling and analysis plan (SAP) should incorporate a quality assurance and quality control (QA/QC)
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A-30 values are not considered statistically different from a blank signal" (Helsel 2005)
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A-31 6.2.3 Accuracy Accuracy is a measure of the closeness of a measurement or the average of a number of measurements to the true value. Accuracy includes a combination of random error as measured by precision and systematic error as measured by bias.
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A-32 Where: t = total concentration found in the spiked sample x = original concentration in sample prior to spiking, and a = actual spike concentration added to the sample 6.2.4 Representativeness, Comparability, and Completeness Representativeness is the degree to which data accurately and precisely represent the natural environment. For stormwater runoff, representativeness is first evaluated based upon the automated flow-composite sample and the associated hydrograph.
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A-33 Target5 Detection Limit Holding Times Accuracy Precision Completeness Analyte Spike Recovery SRM2 Recovery Matrix Spike RPDs Laboratory Duplicate RPDs Conventionals pH 0.1 units Immediately1 -- -- -- 20% 95% Alkalinity 1 mg/L Filter ASAP, 14 days -- -- -- 20% 95% Carbonate 1 mg/L Filter ASAP, 14 days -- -- -- 20% 95% Bicarbonate 1 mg/L Filter ASAP, 14 days -- -- -- 20% 95% Hydroxide Alkalinity 1 mg/L Filter ASAP, 14 days -- -- -- 20% 95% Spec. Conductance 1 mhos/cm 28 days 1 -- 80-120% -- 25% 95% Hardness as CaCO3 1 mg/L 6 months 80-120% 80-120% 25% 20% 95% Calcium 0.01 mg/L 6 months 80-120% 80-120% 25% 20% 95% Magnesium 0.02 mg/L 6 months 80-120% 80-120% 25% 20% 95% TDS 1 mg/L 7 days3 80-120% 80-120% 25% 20% 95% TSS 1 mg/L 7 days3 80-120% 80-120% 25% 20% 95% SSC 1 mg/L 7 days3 80-120% 80-120% 25% 20% 95% TOC 1 mg/L 28 days 85-115% 85-115% 25% 15% 95% DOC 1 mg/L 28 days 85-115% 85-115% 25% 15% 95% Major Ions Sulfate 0.02 mg/L 28 days 80-120% 80-120% 25% 20% 95% Chloride 0.02 mg/L 28 days 80-120% 80-120% 25% 20% 95% Calcium 0.01 mg/L 6 months 80-120% 80-120% 25% 20% 95% Magnesium 0.02 mg/L 6 months 80-120% 80-120% 25% 20% 95% Potassium 0.30 mg/L 6 months 80-120% 80-120% 25% 20% 95% Sodium 0.03 mg/L 6 months 80-120% 80-120% 25% 20% 95% Metals (dissolved4 and total)
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A-34 consistent sampling and processing procedures is necessary for assuring comparability among data sets. Thorough documentation of these procedures, quality assurance activities, and a written assessment of data validation and quality are necessary to provide others with the basic elements to evaluate comparability.
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A-35 Subsamples from each cleaning batch are rinsed with Type 1 laboratory blank water and submitted to the laboratory for analysis. If hits are encountered in any cleaning batch, the entire batch is put back through the cleaning and blanking process until satisfactory results are obtained.
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A-36 C h A P T E r 7 Sample collection, handling, and processing materials can contribute and/or sorb trace elements within the time scales typical for collection, processing, and analysis of runoff samples. The relative effect of potential contamination and/or attenuation of trace elements in runoff samples is a function of the concentrations of major and trace elements, organic chemicals, and sediment in solution.
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A-37 equipment used to collect and process the water samples are free of contamination. 7.1 Laboratory Sample Bottles In order to account for any contamination introduced by sampling containers, blanks must be collected for composite bottles and laboratory bottles used for sample storage for metals analysis.
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A-38 Reporting and Documentation The National Highway Runoff Data and Methodology Synthesis project (Granato, Zenone et al.
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A-39 Electronic data files should be included that contain information on the monitoring sites; rainfall, runoff, sampling data and water quality data associated with each monitoring event; and time series data for seasonal flow and precipitation information. If possible, this information should be provided in a standardized format such as that used by the Caltrans stormwater monitoring program in California (Caltrans 2003)
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A-40 Alpers, C
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A-41 Granato, G
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