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HomeMy WebLinkAbout2010 Shine HUB and Wahl Extraction Area 1101 South Fawcett Avenue, Suite 200 Tacoma, Washington 98402 253.383.4940 June 8, 2011 Jefferson County Department of Community Development 621 Sheridan Street Port Townsend, Washington 98368 Attention: Michelle Farfan Subject: Groundwater, Surface Water and Precipitation Monitoring Shine HUB and Wahl Extraction Area Jefferson County, Washington File No. 1355-035-00 It is our understanding that Miles Sand & Gravel Company will be submitting an application to request modifications to the existing permit conditions pertaining to stormwater at the Wahl Extraction Area. The purpose of this letter is to evaluate the water monitoring program for the Shine HUB and Wahl Extraction Area and, if warranted, propose modifications to the program at the same time. The following letter examines whether the past and current groundwater and surface water monitoring conducted for the Wahl Extraction Area located in Jefferson County, Washington, meets the conditions set forth in the permit and ordinance related to future mining operations. The conditions are set forth by Jefferson County Department of Community Development (DCD) in the Wahl Permit (MLA03-0037) dated July 18, 2005 prepared originally for Fred Hill Materials (FHM) and Ordinance 08-0706-04 (MLA10-00073), Amendment 09-1213-10 dated December 18, 2010. Recommendations for future monitoring at the site are also provided in this letter. CURRENT ORDINANCE AND PERMIT CONDITIONS The purpose of the monitoring program is to collect precipitation, groundwater and surface water data to establish baseline hydrologic and hydrogeologic conditions at the Wahl Extraction Area and to provide a basis for evaluating potential impacts due to future mining operations. In addition, the groundwater monitoring will be conducted to establish a seasonal high water table level. Permit MLA03-0037 page 24, paragraph C states: Prior to the extraction of material from the Wahl Extraction Area, a groundwater and surface monitoring program prepared to DCD specifications shall be submitted to DCD for review and approval. The monitoring program will be prepared by an independent consultant selected by DCD, but at FHM expense. The monitoring program may include additional test/monitoring wells, Jefferson County DCD | June 8, 2011 Page 2 File No. 1355-035-00 rain gauges, and stream monitoring stations for Thorndyke Creek and the unnamed tributary. Groundwater levels shall be monitored weekly for a year once mining commences in the Wahl Extraction Area, and then monthly thereafter to ensure that mineral extraction does not occur within 10 feet of the actual seasonal high water table level (per Condition 11 of Ordinance 08-0706-04). Groundwater monitoring data and stream elevation and flow data shall be collected at a minimum throughout the duration of when mineral extraction is occurring in the Wahl Extraction Area. The monitoring data will be provided to the Washington State Department of Fish & Wildlife, the WA State Department of Ecology, the S'Klallam & Skokomish Tribes, and interested parties. This data will be analyzed and input will be sought prior to the issuance of any additional stormwater permits in Group 2 and 3, which may include adaptive management measures (such as raising the separation between mining and the seasonal groundwater level if impacts to in-stream flows are identified). In addition, prior to issuance of stormwater permits for mining in Group 2 and 3, a new threshold determinations will be required. (Sections 4.24(3) & 8.10(8) of the UDC). Ordinance 08-0706-04, Amendment 09-1213-10, Attachment A, paragraph 11 states: Mining will be limited to a maximum depth of ten (10) feet above the seasonal high water table, which shall be established and monitored pursuant to standard techniques and verified through independent review as arranged by the County at the applicant’s expense. PREVIOUS AND CURRENT MONITORING The original monitoring, initiated in August 2005, was conducted by CR Hydrogeologic Consulting for Fred Hill Materials. GeoEngineers assumed the monitoring duties in November 2009 when Miles Sand & Gravel Company commenced leasing the operations at the Shine HUB and the Wahl Extraction Area. The following are elements of the current monitoring program: Precipitation ■ A weather station was established on the roof of the office building at the current Shine HUB in September 2005. The data, collected on an hourly basis, includes precipitation, temperature and wind direction and speed. The weather station is still functional and provides reliable data. Groundwater ■ Groundwater-level monitoring at the Wahl Extraction Area began in August 2005 with the installation of a pressure transducer and datalogger in Well 9, a monitoring well located in the southwest portion of the Wahl Extraction Area. The automated equipment records the groundwater level on an hourly basis and the information is downloaded quarterly during a visual inspection of the site. The monitoring equipment is still functioning and has provided reliable data. ■ A pressure transducer and datalogger was installed in the Shine HUB water-supply well in April 2007. The equipment malfunctioned in June 2010 and was replaced in September 2010 with new equipment from the same manufacturer. The automated equipment records the groundwater level on an hourly basis and the information is downloaded quarterly during a visual inspection of the site. With the exception of a few months in 2010, the monitoring equipment has provided reliable data. Jefferson County DCD | June 8, 2011 Page 3 File No. 1355-035-00 ■ In January 2010, additional monitoring points of Wells 5 and 8 were added by Miles Sand & Gravel Company to be able to estimate a groundwater surface beneath the Wahl Extraction Area. The installed equipment is of the same manufacturer as the equipment installed in Well 9 and the Shine HUB well. The automated equipment records groundwater levels on an hourly basis and the information is downloaded quarterly during a visual inspection of the site. The monitoring equipment provides reliable data. Surface Water ■ Three surface water stations were established in September 2005 on Thorndyke Creek near the Wahl Extraction Area. One of the stations is located on an unnamed tributary and two are located on Thorndyke Creek above and below the confluence of the unnamed tributary. The stream stage height is recorded on an hourly basis using automated equipment. The streamflow is measured manually on a quarterly basis by wading the stream and measuring stream velocity. ■ An additional surface water monitoring point is located on Thorndyke Creek approximately 1 mile upstream of its mouth. The stream stage height is recorded on an hourly basis using automated equipment. The stream flow is measured manually on a quarterly basis by wading the stream and measuring stream velocity. SUMMARY It is our opinion that the monitoring data being collected at the Wahl Extraction Area meets or exceeds the requirements stated in the permit and ordinance pertaining to monitoring. When the permit and ordinance were issued, it was anticipated that mining in the Wahl Extraction Area would commence prior to acquiring significant groundwater data. However, mining has not yet commenced to date and several years of background groundwater and surface water data have been acquired. In addition, Miles Sand & Gravel Company has improved upon the monitoring program established in 2005 by adding two groundwater monitoring points, replacing and upgrading failing equipment, and adjusting the locations of surface water monitoring points to better record stream gage heights. The data will provide baseline hydrologic and hydrogeologic conditions for the area and can be used to establish a seasonal high water table. The use of automated dataloggers facilitates the collection of more data than was anticipated in the permit conditions, both in terms of frequency and locations. Because there is a near continuous record of groundwater levels at the Shine HUB and Wahl Extraction Area since August 2005, there is no need to measure the groundwater levels on a weekly basis as stated in MLA03-0037, page 24, paragraph C. The current monitoring program exceeds this requirement by recording groundwater levels on an hourly basis with the instrumentation installed in the three monitoring wells located within the Wahl Extraction Area. Jefferson County DCD | June 8, 2011 Page 4 File No. 1355-035-00 RECOMMENDATIONS The following are our recommendations for future monitoring: Monitoring Program ■ Maintain the Shine HUB weather station. If the facilities at the Shine HUB are moved to near the Wahl Extraction Area, the weather station should also be moved and reestablished. ■ Continue to monitor groundwater levels in three monitoring wells using the installed transducers that record water levels hourly. On a quarterly basis, download the recorded water level data, manually measure the water level for calibration, and service the instruments. If Wells 5, 8 and 9 are encroached upon by mining operations, they each should be replaced by comparable existing monitoring wells or new monitoring wells installed outside the proposed mining area. ■ Continue monitoring groundwater at the Shine HUB water supply well using the installed transducer. On a quarterly basis, download the recorded water level data, manually measure the water level for calibration, and service the instrument. When this well is no longer used for the sand and gravel facility, the transducer will be removed and groundwater level monitoring at this location will be terminated. ■ A new water supply well will be installed near the processing area adjacent to the Wahl Extraction Area. Prior to use, a transducer will be installed in this well to monitor groundwater levels. ■ Continue to monitor surface water at the four stream locations. On a quarterly basis, download the recorded staff height data, record stage height for calibration, and wade the stream to measure streamflow. Reporting ■ On an annual basis, submit a memorandum to Jefferson County DCD. The memorandum will include hydrographs of the complete datasets for precipitation, groundwater levels, stream stage heights and streamflow measurements. The memorandum will also include a summary of any instrumentation modifications, data loss, or significant events that occurred within the monitoring year. The submittal will also include the complete datasets as spreadsheets on a compact disk. It is our intent for this process to be as straightforward and open as possible. We are comfortable providing the recommendations noted herein as we feel they exceed standard monitoring and reporting procedures for this type of project.