A White Paper Describing a Watershed-based Monitoring Network Design for the Purgatoire River Basin

Transcription

1 A White Paper Describing a Watershed-based Monitoring Network Design for the Purgatoire River Basin This white paper summarizes a watershed-based monitoring network design for the Purgatoire River Basin, generally within the headwaters of the Purgatoire River and associated tributaries between the Town of Stonewall and Trinidad Lake. The study area of the Purgatoire River Basin (the watershed ) is west of the Town of Trinidad, Colorado in Las Animas County. The watershed covers approximately 400 square miles located between Interstate 25 and the Sangre de Cristo mountain range (Figure 1). Figure 1. Purgatoire Watershed General Location

2 Monitoring Network Design Tetra Tech, Inc., a national environmental engineering consulting firm, is implementing a comprehensive watershed monitoring program in the Purgatoire watershed. The monitoring will commence in April 2010 to collect and evaluate surface water data in areas of the Purgatoire River watershed influenced by coalbed methane (CBM) operations. Currently, the CBM operators in this watershed have approximately 3,500 CBM extraction wells with approximately 10 MGD of produced water discharged in the basin. The affects of CBM produced water are not well understood in the Purgatoire River watershed. Therefore, the six objectives of the watershed monitoring program are: 1. Provide water quality data to more fully understand and evaluate CBM influences on surface water quality and loading to tributaries and ultimately, the Purgatoire River both upstream and downstream of Trinidad Lake. 2. Provide continued hydrologic and surface water quality data for the evaluation of the upper Purgatoire River and associated tributaries throughout various flow regimes. 3. Evaluate pollutant loads, trends in the concentrations, and assimilative capacity to develop management scenarios, creative options and control strategies to achieve permit compliance. 4. Allow a comprehensive, site-wide comparison of water quality constituents of concern to applicable permit limits and WQCC water quality standards. 5. Understand sodium adsorption ratio (SAR) and electrical conductivity (EC) relationship in the watershed as it relates to irrigated agriculture and classified uses. 6. Provide a scientific and technical basis to support permitting and water management options that could be presented to the Water Quality Control Division (WQCD) to support permit amendments or regulatory options that could be introduced to the Water Quality Control Commission (WQCC) at the informational scoping issues hearing for the Arkansas River basin in October The watershed monitoring program supports the approach of communicating information and promoting data transparency. Interested parties will be able to review water data via continuous satellite monitoring stations monitoring near real-time and monthly data collected and made available via a website. The watershed monitoring program includes 25 locations on the Purgatoire River and associated tributaries (Figure 2). Ten sample locations are on the mainstem or Middle Fork of the Purgatoire River while fifteen locations are on tributaries to the Purgatoire River. The basis for each of these sampling locations is summarized in Table 1. Nine of the twenty five monitoring locations will have continuous gaging stations to monitor flow and/or water quality. The continuous monitoring equipment will measure streamflow, ph, specific conductance, temperature, and chloride at 15-minute intervals.

3 Table 1. Purgatoire Watershed Sampling Locations

4 All 25 sampling locations will include monthly surface water collection and analysis for constituents presented in Table 2. Table 2. Analyte List and Methods for Sampling of Surface Water in the Purgatoire River Watershed Field Parameters Metals Wet Chemistry Constituent U.S. EPA Method Number Sample Preservation and Treatment Holding Times ph Immediately Specific Conductance Measure In-Situ 28 days Temperature Immediately Boron D,T ICP Acidify with HNO 3 ; ph <2 6 months Calcium D ICP Acidify with HNO 3 ; ph <2 6 months Copper D, PD, TR ICP-MS Acidify with HNO 3 ; ph <2 6 months Iron D, TR ICP Acidify with HNO 3 ; ph <2 6 months Lead D, PD, TR ICP-MS Acidify with HNO 3 ; ph <2 6 months Magnesium D ICP Acidify with HNO 3 ; ph <2 6 months D, PD, Selenium ICP-MS Acidify with HNO 3 ; ph <2 6 months TR Sodium D ICP Acidify with HNO 3 ; ph <2 6 months Zinc D, PD, TR ICP Acidify with HNO 3 ; ph <2 6 months Alkalinity SM2320B - Titration Chill to 4 degrees C 14 days Chloride SM4500 Chill to 4 degrees C 28 days Sulfate Gravimetric Chill to 4 degrees C 28 days Total Suspended Solids (TSS) Total Dissolved Solids (TDS) Gravimetric Gravimetric Chill to 4 degrees C Chill to 4 degrees C 7 days 7 days NOTES: 1. D = Dissolved form analysis. 2. PD = Potentially dissolved form analysis. 3. T = Total form analysis. 4. TR = Total recoverable form analysis. 5. Filtration performed in the field at the time of sample collection. 6. Sodium Adsorption Ratio (SAR) calculated based on dissolved calcium, magnesium, and sodium concentrations.

5 Overview of Program Tasks The watershed monitoring program will include continuous monitoring at nine stations (incorporating electronic flow and water quality (i.e., ph, temperature, EC, and chloride) and routine (monthly) surface water sample collection and analyses at a total of 25 locations. An overview of the monitoring tasks included in this program is summarized below: 1. Develop a sampling analysis plan. 2. Install nine continuous monitoring gaging stations and associated continuous flow and water quality (i.e., ph, temperature, EC, and chloride) equipment at select Purgatoire River and tributary locations. 3. Perform monthly surface water grab samples and streamflow measurements at 25 locations in the Purgatoire River and select tributaries. 4. Operate and maintain continuous monitoring stations, including calibration of equipment and radio telemetry. 5. Evaluate and analyze data; perform quality assurance/quality control (QA/QC) evaluations on collected data; manage data in one database suitable for viewing and analysis. Summarize and report findings. 6. Communicate near real time data (15-minute intervals) via the Colorado Division of Water Resources (DWR) website; communicate monthly data, information, and updates on a Purgatoire Watershed Monitoring Website. 7. Conduct meetings with operators and stakeholders to support permitting, regulatory and stakeholder processes. The following summarizes the tasks to meet the project goals. Task 1. Sampling Analysis Plan The Sampling and Analysis Plan (SAP) provides guidance for field personnel by defining, in detail, the number, type, and location of samples to be collected and the type of analyses to be performed. Additionally, the SAP will reference standard operating procedures to ensure that monitoring is performed in accordance with industry standards and that the data generated from event-toevent are comparable. Task 2. Installation of Continuous Monitoring Stations The main focus of operating and maintaining continuous flow and water quality monitoring stations is to assess the hydrological and geochemical conditions of the Purgatoire River and select tributaries during time periods other than when monthly surface water sampling events occur. Another important feature regarding continuous monitoring is evaluating long-term (seasonal) and shortterm (storm events) flow and water quality changes in the Purgatoire River and select tributaries.

6 Gage stations will incorporate a Sutron Accubar constant flow bubbler-type pressure gage that measures the depth of streamflow and converts the depth to an appropriate discharge. Continuous water quality (i.e., ph, temperature, specific conductivity, and chloride) monitoring will utilize a Hach DS-5 Multiprobe. Data measured by flow and water quality equipment will be stored on Sutron SatLink2 data collection platforms (DCP) at 15-minute intervals. The DCP, bubbler-type gage, and other associated equipment will be housed in a metal gage enclosure to protect from weather and vandalism. A polyvinyl chloride (PVC) enclosure will be constructed around the water quality probe and cable to help protect from weather and vandalism. Sutron Corporation will provide the hardware, software, and satellite transmission of near-real time gaging station data for the Purgatoire watershed monitoring project. The flow and water quality data will be transmitted to satellite links by each DCP at set intervals (e.g., 15-minute intervals). Data will then be available for viewing via a world-wide-web site operated by Sutron and linked to the Purgatoire webpage. Task 3. Monthly Surface Water Monitoring The Purgatoire River basin site-wide monitoring program will incorporate 25 sample locations as outlined in Table 1. Sample locations are selected to: Provide background surface water quality and flow data in the South, Middle, and North Forks of the Purgatoire River prior to CBM discharge influences. Provide surface water chemistry and flow data in tributaries influenced by CBM operations to evaluate their impact on the Purgatoire River. Evaluate changes in water chemistry and flow along the mainstem of the Purgatoire River from above CBM influences to below Trinidad Lake, where agricultural diversions generally occur. Provide surface water data that supplements historic sampling data, where available. Provide the optimal location for continuous flow and water quality monitoring equipment to support project objectives. Monthly surface water monitoring will utilize two field teams responsible for sitewide sample collection and streamflow measurement. Tetra Tech will provide one field leader for each sample team. Sampling will be performed to evaluate chemistry and load changes in the surface water. Monthly monitoring will allow the evaluation of seasonal water quality trends within the Basin. For example, the May/June monitoring events will target seasonal snowmelt runoff when the ratio of CBM produced water to Purgatoire River flows are generally lowest. Alternatively, the December through February monitoring events will target seasonal baseflows when the ratio of CBM produced water to Purgatoire River flows are generally highest.

7 The monthly sampling will likely be performed over a two day period due to the size of the Purgatoire River basin from Stonewall (uppermost sample location) to Trinidad Lake. A sample will be collected on the second day at a location where sampling ended on the first day. This duplication in sampling will allow correlation between the two day sampling periods. In accordance with standard water quality protocol, each team will collect field duplicate and equipment rinsate blank samples for QA/QC purposes during each event. Sampling teams will collect field measurements (i.e., ph, temperature, and EC) at each sample location. Surface water samples will be collected and placed in sample bottles provided by the laboratory. Sample aliquots collected for dissolved analyses will be field filtered using a 0.45 micron filter. Upon collection, the samples will be placed in a chilled cooler for shipment under chain-of-custody procedures to ACZ Laboratories, Inc. for analytical testing. The analytical suite for each sample incorporates the analyses presented in Table 2. Stream discharge will be measured at each sample location using portable cutthroat flumes or the equal-width-increment method (ASTM Standard D ) for flows greater than 0.5 cubic feet per second (cfs). Task 4. Operation and Maintenance of Equipment/Hardware Operation and maintenance of the flow and water quality monitoring equipment includes programming and setup of DCPs and bubbler-type gages, cleaning and calibrating the water quality probes and the bubbler-type gages at least once per month, replacement of chloride probe sensors every six months, and monthly rating curve development and calibration for streamflow monitoring. Task 5. Data Management & Reporting Data obtained throughout the monitoring program (i.e., analytical data, manual flow and water quality data) will be maintained by Tetra Tech in a Microsoft Access database. Prior to importing data into the database, a data usability assessment will be conducted on water chemistry data to ensure proper data quality. Tetra Tech will evaluate the surface water monitoring results following each calendar year of monitoring and provide a data summary/evaluation report to each member of the CBM consortium. The report will include a summary of continuous flow and water quality data collected during the year as part of this surface water monitoring program. The summary report will include tabular and graphical representations of collected data and an evaluation of the data including noticeable chemistry and loading trends and how they compare to permit limits. Task 6. Communication/Website A Purgatoire Watershed Monitoring Program website will support the communication goals of the project. The website will be used to communicate progress, news, and water quality and flow data. The Sutron real-time data will also be linked to the website to communicate near real-time data and information.

8 Task 7. Meetings Periodic meetings with the operators, stakeholders, and regulators are also identified to promote communication and keep discussions and project next steps moving forward. Schedule The surface water monitoring program will be initiated prior to the 2010 spring snowmelt runoff 1. Tetra Tech personnel will start implementing the monitoring program immediately and begin surface water sampling in April 2010, with appropriate access agreements being addressed in advance. The initial year of the surface water monitoring program will be from April, 2010 through December 31, The subsequent year s monitoring program will begin on January 1, 2011 and continue through December 31, All data collection efforts will compliment the upcoming Arkansas River Scoping Issues Hearing scheduled for October Historical streamflows in the Purgatoire River at Madrid (upstream of Trinidad Lake) show that snowmelt runoff generally begins in late-march/early-april and continues through late-june/early-july (