Guidebook for Selecting Methods to Monitor Airport and Aircraft Deicing Materials (2017)

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

18 C h a P T E r 3 3.1 Screening of Monitoring Types Monitoring type refers to the general means by which samples are collected and analyzed. For the purposes of this guidebook, monitoring type falls into two main categories: • Off-site monitoring types, and • On-site monitoring types. Off-site monitoring refers to the most traditional type of monitoring—where the sample is collected on-site and is shipped off-site for laboratory analysis. On-site monitoring refers to the type of monitoring where the sam- ple is collected on-site and also analyzed on-site. In this guidebook, the on-site monitoring type is further divided into three subcategories: handheld, test kits, and online. Monitoring-type screening is performed to define which types of monitoring are appropriate for use at a particular airport. The airport operator can use the Parameter Screening Worksheet at the end of Chap- ter 2 as the starting point and select the monitoring types that are appli- cable for each parameter. Selection of monitoring types should take into consideration the data needs for each parameter at each monitoring location. The first decision in the screening process is whether the samples should be analyzed off-site or on-site. The number of samples that must be collected to meet the data objectives, the time- frame when sample results must be known, the frequency at which data points are needed, and data quality requirements will be the determining factors as to whether an off-site monitoring type or on-site monitoring type is selected. 3.2 Off-Site Monitoring Types The traditional means for collecting stormwater monitoring data is sample collection and off-site laboratory analysis of the samples. Samples are col- lected at the sites of interest, either manually or with auto-samplers, and sent off-site to an analytical laboratory. A wide variety of laboratory analyti- cal methods are available. Although the laboratory monitoring methods associated with the off-site monitoring type can be more rigorous because of the quality control performed at laboratories and the fact that analyses are conducted in a controlled environment, the off-site monitoring type as Identify Applicable Monitoring Types Off-Site Monitoring Selected √ Few samples required (i.e., daily). √ Time delay for result is acceptable. √ High data quality required.

Identify applicable Monitoring Types 19 a whole has several potential disadvantages, the severity of which is site-specific. The possible disadvantages include that: • Sampling, particularly if performed manually, can be expensive because of labor costs; • The logistics and timing of dispatching sampling staff can be a challenge, especially if sam- pling sites are difficult to access or adverse weather presents a safety hazard; • There are typically regulatory requirements for sample handling, transportation, and storage; • Only the stormwater characteristics at the time of sample collection are measured; • It can be difficult to capture the variability of stormwater characteristics or catch particular conditions, such as peak deicer discharge periods; • Hold times for analytical samples can provide constraints in developing the desired sampling program; • Typically there is a delay before results are available from the laboratory, ranging from 1 to 3 weeks; and • Real-time decisions cannot be made based on sample results. Some parameters (e.g., temperature and flow) cannot be measured by off-site methods. Other parameters (e.g., pH, DO) have very short hold times, which typically precludes analy- ses by off-site methods for these parameters. The other parameters have on-site or off-site methods that may be applicable for monitoring airport stormwater discharges. 3.2.1 Laboratory Methods Associated with Off-Site Monitoring Table 3.1 lists the analytical methods for stormwater monitoring of typical airport deicer parameters. 1Value is measurement precision. EPA Method Source: Methods for the Chemical Analysis of Water and Wastes (U.S. EPA, 1983) AOAC: Association of Official Agricultural Chemists; DOC: dissolved organic carbon Table 3.1. EPA-approved methods for the water quality parameters typical for stormwater and deicer monitoring.

20 Guidebook for Selecting Methods to Monitor Airport and Aircraft Deicing Materials To obtain reliable analytical data, strict quality assurance/quality control (QA/QC) proce- dures should be followed during stormwater sampling activities. These procedures include the use of qualified professionals, use of a certified analytical laboratory, and proper sampling methods and chain-of-custody procedures. 3.3 On-Site Monitoring Types On-site monitoring types involve on-site collection of samples and on-site analysis of the sam- ples. The analyses associated with this monitoring type may be conducted right at the sampling location or somewhere else at the airport site. The analytical results from on-site monitoring are generally available much more quickly than the results from off-site monitoring, leading to better ability to make real-time decisions. The analytical methods associated with on-site monitoring are typically limited to those that can be performed automatically or with a few simple steps. The quality control performed for the analytical methods associated with on-site monitoring is generally less rigorous than the laboratory methods associated with off-site monitoring. For instance, laboratories typically will analyze samples spiked with compounds of interest to check for interferences and perform calibrations checks. These types of quality control sample checks are not typically performed with methods used in on-site monitoring. However, according to the manufacturers’ information collected as part of this project, the accuracy of analytical methods associated with on-site monitoring is consistent with similar laboratory methods. Therefore, if the appropriate calibrations and maintenance are performed, and the user is knowledgeable in the use of the method, on-site monitoring can provide results that are as accurate as off-site laboratory methods. 3.3.1 Types of On-Site Monitors Once the parameters that require on-site monitoring are identified, the next step in the pro- cess of implementing the monitoring system is selecting the monitoring types. The monitoring types, for purposes of this guidebook, are handheld monitors, test kits, and online monitors. The monitoring types are defined in the following sections. Selection of the proper monitoring type will allow for the desired monitoring approach to meet the data requirements while minimizing the maintenance needs of the system. For some parameters, some of the monitoring types are not available. 3.3.1.1 Handheld As defined in this report, the term handheld monitor refers to any type of on-site monitor that is typically carried out to the sample site to perform the measurement (see Figure 3.1). Both the sampling of the water stream and the analytical function are accomplished by the portable monitor. Handheld monitors typically have an electrode that is inserted into the stream that is to be sampled. The most common of this monitoring type is the pH meter. Handheld monitors are typically less expensive to purchase and require less capital for main- tenance than other monitor types. Handheld monitors typically have low operation and main- tenance (O&M) costs. The primary maintenance function typically required is calibration. Handheld monitors are generally easy to operate accurately with proper study and understand- ing of the instruction manual. Handheld monitors are portable and can be used for monitoring multiple locations; however, the units may have shorter service lives than the other types of monitors because they are subjected to field conditions. Monitoring only occurs when personnel are present to perform the monitoring. On-Site Monitoring Selected √ Many or continuous samples required. √ Results used for real-time decisions. √ Lower data quality is acceptable. Figure 3.1. Example of a handheld monitor: a pH meter.

Identify Applicable Monitoring Types 21 Handheld monitors typically require periodic calibration, ranging from every few hours for pH meters to approximately annually (or longer) for temperature meters. Handheld monitors also typically require some maintenance, such as replacement of batteries, replacement of probes or probe membranes, and replacement of solutions. The maintenance is generally easier than the maintenance required for the equivalent laboratory equipment. Use of handheld units is the most common type of monitoring for measuring pH, DO, and temperature. 3.3.1.2 Test Kits As defined in this report, the term test kit refers to any type of monitor system for which a sample is collected and analyses are performed by airport personnel on the airport site but away from the sample location—typically in an on-site laboratory area (see Figure 3.2). Test kit sys- tems typically require reagents and require several steps for analysis. The most commonly used test kit system at airports consists of chemical test vials and a spectrophotometer. Test kits are typically slightly more expensive than handheld monitors to purchase. Test kits typically have longer service lives than handheld monitors if they are maintained properly, but they may require more capital expense for consumable parts than handheld units. The test kit methods range from easy to moderately difficult to use, depending on the procedures required for the parameter. Some test kits are portable and can be taken into the field, but typically analy- ses are performed in an on-site area set up as a laboratory. The analytical instruments of test kits typically require periodic main- tenance and calibration. Similar to handheld monitors, the maintenance is generally easier than the maintenance required for the equivalent labora- tory equipment. The test kit methods for some parameters differ from the methods used at an off-site laboratory. Comparison of test kit results to off-site laboratory–based results is recommended to verify that results are sufficiently similar, especially at the extremes of the applicable concentra- tion ranges. Historically, test kit monitors were considered an easier-to-use, less sophisticated means of performing analytical testing at the sampling site. One of their primary advantages is faster turnaround time for analytical results. Test kit analyses could be performed very near to the sampling site—for example, in a vehicle at the sample collection site—which reduces sample holding time and reduces delay in getting analytical results. As tech- nology has progressed, the boundary between test kits and some analytical methods performed by certified laboratories has blurred. An example of this is the COD analyses commonly performed on-site at airports, which are based on the laboratory method for COD analyses. There are now a wide variety of parameters that can be analyzed using test kits, although the number of parameters with available test kits is not as extensive as the number of parameters that can be analyzed with off-site analyses. Some test kit methods have been approved for compliance purposes. 3.3.1.3 Online Online monitors are permanently mounted devices designed to sample flow streams and analyze the samples on a regular basis without direct involvement of facility staff (see Figure 3.3). The online monitors are the only type where the sample is analyzed directly without the sample-to- sample intervention of airport personnel. Automatic collection of data Data Sondes Data sondes are portable monitors that perform functions similar to a permanently mounted online moni- tor. Data sondes can be temporarily placed into a stream or stormwater structure and left for an extended period of time to collect analytical data. The units can collect significant amounts of monitoring information at short measurement intervals using sensors installed in the instrument. The parameters measured are limited to those that can be analyzed using electrodes (i.e., ammonia–nitrogen, pH, DO, temperature, and TSS). Data sondes store the data internally in the data sonde hardware until the data are retrieved using a portable com- puter. Data sondes are most typically used for collecting data during studies such as water quality assessments. The battery life of a data sonde is approximately 30 days, and the mem- ory capacity is approximately 190 days for multiparameter-monitoring data sondes. Figure 3.2. Example of a test kit: a COD digester.

22 Guidebook for Selecting Methods to Monitor Airport and Aircraft Deicing Materials allows substantial quantities of data to be collected under a wide variety of conditions, eliminat- ing the need to mobilize staff for limited sampling events. Online monitors also greatly increase the chances of characterizing unpredictable swings in stormwater characteristics that are a com- mon occurrence with deicer discharges. Online monitors store the analytical data and most can transmit the data over computer or phone lines. Because online monitors collect and analyze samples automatically, data from online monitors can be used to make real-time decisions such as stormwater flow diversion. While online monitors collect and analyze samples without facility staff present, staff involvement is neces- sary to facilitate calibration, verify results, troubleshoot, perform preventative maintenance, and achieve proper operation of the instruments. Without proper care and periodic personnel visits, data from online monitors could provide incorrect information, which may affect stormwater and deicer management system control decisions. While the staff is needed for maintenance, the labor hours required per sample analyzed are typically far less than those required for monitoring types that require sampling by staff. Online monitors take measurements in one of two ways: • A sensor is installed in the sample stream, or • A sample is automatically collected and then analyzed within the unit. For monitor types where the sensing unit is placed directly in the sample stream, periodic observation and maintenance of the sensors are required to verify that the sensor is submersed and clean. In stormwater containing deicer, the sample streams can have significant biogrowth, which can cover the electrode. Electrodes should be cleaned periodically to prevent the build- up of biogrowth. Some of these submersible units have automatic cleaning functions that can reduce the need for manual cleaning. For monitors that collect and analyze samples within a unit that is not directly submersed in the sample stream, a sample collection system is typically required to convey the sample to the moni- tor. The sample collection system includes pumps to continuously transfer samples of the stream to the unit, filters or other sample-conditioning equipment, and piping to deliver the sample to the monitor. Since the organic content is typically high, there can be biogrowth in sample systems such that they require cleaning. Inside the equipment, small-diameter tubing can also become clogged with biogrowth, requiring periodic maintenance of the unit. Online monitors may not be truly continuous, depending on the method, because some units require discrete blocks of time to perform the individual analyses. Several minutes may be required for some methods. Online monitors are generally more complex to operate and troubleshoot. Despite their sophistication and capabilities, online monitors are typically not plug-and-play. Airport oper- ators seeking accurate and reliable results will need to understand that the units need to be set up, calibrated, and maintained in a way that takes into consideration the environment in which they are used, the characteristics of the samples they are measuring, and the data that are being sought. Online monitors require maintenance, periodic calibration, and checks by airport personnel. Several parameters require reagent tanks to be refilled periodically. Most units require temperature-controlled environments for electronic equipment and freeze pro- tection of the sample or reagents. Also, data may need to be downloaded in the field to maintain a historical record unless tele- metry or a communication system is installed with the monitoring system. Figure 3.3. Example of an online monitor: a TOC monitor.