Interpreting the Results of Airport Water Monitoring (2017) / Chapter Skim
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Pages 97-120
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From page 97... ...
97 C h a p t e r 3 3.1 Introduction This chapter addresses the application of water monitoring data. Application of monitoring data is defined in this guidebook as the use of sufficiently vetted and statistically interpreted water monitoring data to support the airport's decision-making processes.
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From page 98... ...
98 Interpreting the results of airport Water Monitoring Best Management Practice – A term that sometimes encompasses mechanisms for the ongoing control and treatment of stormwater runoff. The 2015 MSGP uses the term "control measures" to refer to BMPs.
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applying and responding to Monitoring Data 99 3.3 Application 1: Responding to Regulatory Compliance Issues Regulatory compliance issues are associated with situations where monitoring data indicate that a permit condition has been, or has significant potential to be, violated. When water-related compliance issues first appear, they can be challenging for airports because: • Issues often appear without warning.
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From page 100... ...
100 Interpreting the results of airport Water Monitoring Review the Data A review of water monitoring data should follow, wherein the extent, accuracy, and representativeness of the data is initially characterized. The objectives of the review are as follows: • To identify data that can be explicitly verified (e.g., review field observation sheets, chain-ofcustody forms, QA/QC documents, etc.)
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From page 101... ...
applying and responding to Monitoring Data 101 Airports subject to the U.S. EPA MSGP are required, on the same day a condition requiring corrective action is found, to take all reasonable steps to minimize or prevent the discharge of pollutants until a permanent solution is installed and made operational.
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102 Interpreting the results of airport Water Monitoring Metadata The numeric monitoring data should be supplemented with metadata. Metadata is a term for information describing the contents and context of data.
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applying and responding to Monitoring Data 103 may have been occurring for some time prior to a non-compliance incident. Review of historical field condition observations and related parameters may also help identify when the circumstances leading to the compliance issue started.
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104 Interpreting the results of airport Water Monitoring If the airport has already determined the likely cause of the issue, consider describing in detail the likely cause in the report to the regulator. If the airport has already taken steps to address the issue, or if steps are already planned to address the issue, these actions should also be described to the regulator.
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applying and responding to Monitoring Data 105 The ultimate purpose of a source investigation using root cause analyses or other investigative techniques is to identify the source and extent of the issue causing the water quality concern such that solutions to the issue can be developed and the airport can meet its compliance requirements. A source investigation does not necessarily have to use root cause analysis techniques, but those techniques are recommended.
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106 Interpreting the results of airport Water Monitoring Several root cause analysis techniques can be applied to water quality or quantity issues, including the following: 1. Time Sequencing a.
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applying and responding to Monitoring Data 107 3. Upstream Tracing a.
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108 Interpreting the results of airport Water Monitoring 3.4 Application 2: Using Data in Establishing Permit Conditions Monitoring data collected by airports can also be used to support future regulatory activities. These can include permit re-applications or establishing new or modified permit conditions.
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From page 109... ...
applying and responding to Monitoring Data 109 It is a process regulators use to determine whether a water quality-based effluent limit and/or routine monitoring is required in an NPDES permit. The regulator often uses data collected by the airport to conduct the reasonable potential analysis.
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110 Interpreting the results of airport Water Monitoring Mass Flow Pollutant Concentration Cr Qs Cs Qd Cd / Qr ( ) = = + Where: Qs = Receiving water flow upstream of the stormwater discharge Cs = Background pollutant concentration in the receiving water Qd = Stormwater discharge flow Cd = Pollutant concentration in the stormwater discharge Qr = Resultant flow downstream of the stormwater discharge Cr = Resultant pollutant concentration in the receiving water The waste load allocation calculation is a mass balance calculation that takes into account flows and pollutant concentrations upstream of the potential discharge.
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From page 111... ...
applying and responding to Monitoring Data 111 potential to be used for the purposes described in the use designation or that the use designation cannot be met because of factors outside the control of the discharger, such as the following: • Naturally occurring pollutant concentrations • Flow conditions • Human-caused conditions or sources of pollution that cannot be remedied or would cause more environmental damage to correct than to leave in place • Hydrologic modifications that preclude the attainment of the use • Physical conditions related to the natural features of the water body • Controls would result in substantial and widespread economic and social impact [Water Quality Standards, 40 CFR §131.10 (1983, Revised 2015)
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From page 112... ...
112 Interpreting the results of airport Water Monitoring Alternate Monitoring Methods When proposing an alternate monitoring method, the onus is on the airport to prove that the alternate monitoring method can adequately characterize the presence and concentration of the potential target pollutant in the stormwater discharge. The alternate method should be able to quantify the concentration with the desired level of accuracy at the water quality limit.
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From page 113... ...
applying and responding to Monitoring Data 113 3.5 Application 3: Applying Monitoring Data to Support Operations and Improve Airport Stormwater Quality Airports often have need for monitoring of water streams to support a variety of activities not directly associated with permit compliance or development of new or modified permits. For many of these activities, the primary purpose of collecting water monitoring data is to support ongoing planning, design, operations, and maintenance activities.
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From page 114... ...
114 Interpreting the results of airport Water Monitoring • Stormwater BMP controls – Low impact development infiltration–based controls b Swales b Filter strips b Bioretention basins b Permeable pavement – Cartridge filter systems – Detention and settling basins – Constructed wetlands – Oil–water separators • Remediation systems The types of pollutants and the extent of the monitoring data needed to support the selection, sizing, and design of stormwater infrastructure vary. The extent that field monitoring data is needed also depends upon the extent to which model estimates are used.
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From page 115... ...
applying and responding to Monitoring Data 115 3.5.2 Management of Ongoing Operations and Maintenance Activities Most airports have some type of stormwater control infrastructure to manage water quantity and quality. Typical functions for the stormwater infrastructure include the following: • Monitoring systems for flow and pollutant concentrations • Mechanisms such as valves, gates, weirs, and pump stations for segregating flows of different pollutant concentration • Storage of stormwater of varying pollutant types and concentrations • Oil–water separator units • Stormwater BMP controls intended to remove solids and attached pollutants (e.g., metals, PAH, pathogens)
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From page 116... ...
116 Interpreting the results of airport Water Monitoring The monitoring associated with operations and maintenance typically falls into two types: • Periodic or as-needed monitoring via grab samples/laboratory analysis or handheld instruments • Real-time monitoring – Monitored data made available to operators on computer screens to see trends and outliers – Data linked to control system for computer-control automatic process adjustments such as opening valves, chemical dosing, and collecting samples The type of monitoring needed to support stormwater infrastructure operations and maintenance is situation specific. Considerations in selecting the monitoring parameters, types, methods, extent, and frequency include the following: • How quickly is the data needed?
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From page 117... ...
applying and responding to Monitoring Data 117 3.5.3 Tracking and Improving Environmental Performance Discharge permit limits and benchmarks often "set the floor" regarding water quality and environmental performance. Airports may have policies and goals in place to further improve water quality or manage environmental performance to reduce the likelihood that water quality issues arise.
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From page 118... ...
118 Interpreting the results of airport Water Monitoring 3.6 Application 4: Stakeholder Communication and Public Outreach While not technically part of a monitoring program, effective public outreach can allow an airport to tout successes measured by the monitoring program and to manage public perception of issues. Keys to effective public outreach include proactively disseminating information, particularly when related to an issue; providing appropriate background information to facilitate complete understanding of the monitoring data provided; and anticipating and proactively responding to public concerns.
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From page 119... ...
applying and responding to Monitoring Data 119 reduction in effluent limit exceedances, or 10 percent reduction in metals concentrations at the outfall. Be cautious of providing tables of data that may be difficult to digest, or using statistics that are not commonly understood.
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120 Interpreting the results of airport Water Monitoring cleanup. Focus on examples of the positive impact of the airport on the community.
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