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HomeMy WebLinkAbout073David W. Johnson From: Sent: To: Cc: Subject: Attachments: Pearch, John (ECY) [JOPE461 @ECY.WA.GOVI Tuesday, December 08, 2009 5:09 PM Susan Porto David W. Johnson FW: Pleasant Harbor HG Memos from Ecology Ecology-Pearch Part I Hydrogeologic Memo Pleasant Harbor chloride sampling text.pdf; Ecology-Pearch Part I Figure 9 and 10 and APPENDICES.pdf; Ecology-Pearch Part ll Hydrogeologic Memo Pleasant Harbor aquifer test and monitoring review.pdf Hi Susan, Long time coming for this! See Appendix C for the wells to be updated in the SIPZ. I haven't heard back from Scott Bender or PH's attorney yet on what they agree or don't agree with but thought l'd send you this anyways. Thanks to you and your staff for all your help in gathering all the building permit data. Let me know if you have any questions John John Pearch, L.H.G. (#1410) Hydrogeologist and Well Drilling Coordinator Southwest Regional Office - Water Resources Program Department of Ecology PO Box 47775 Olympia, WA 98504-7775 Phone: 364-407-0297 Fax: 360-407-6305 Email: JOPE461 @ecy.wa.qov From: Pearch, John (ECY) Sent: Friday, December 04,2009 7:05 PM To: Crane, Philip (ECY) Cc: Gallagher, Mike (ECY); 'Peter Schwartzman'; 'Jill Van Hulle'; 'Scott Bender' Subject: Pleasant Harbor HG Memos from Ecology Phil, Attached are two Memos that pertain to Pleasant Harbor Water Right Application G2-30436. Due to the amount of information in the chloride sampling, I divided the memo into two Parts 1) Hydrogeologic Memo Part I: Chloride Sampling in Coastal Domestic Wells on the Black Point Peninsula, Jefferson County, Washington, pertaining to Water Right Application G2-30436 <<Ecology-Pearch Part I Hydrogeologic Memo Pleasant Harbor chloride sampling text.pdf>> <<Ecology- Pearch Part I Figure 9 and 10 and APPENDICES.pdf>> 1 2) Hydrogeologic Memo Part II: Aquifer test review and monitoring requirements pertaining to Water Right Application G2-30436 <<Ecology-Pearch Part ll Hydrogeologic Memo Pleasant Harbor aquifer test and monitoring review.pdf>> The Part I addresses specific recommendations to monitoring in coastal domestic wells and the Pleasant Harbor's neighborhood water policy. I plan to eventually send this memo to all the domestic well owners that I sampled from. Part ll addresses several topics, regarding the ACG Well Aquifer test, PGG's analytical groundwater flow model, and specific requirements for monitoring and production wells. PGG's model should be included in the ROE. I included monitoring provisions to also be included in the ROE. lf you have any questions or concerns about my memos, please let me know as soon as possible and we can discuss anything that needs further clarification. I hope we all can eventually agree to these recommendations/requirements. I have spent a considerable amount of time on these memos while I transition into my new appointment as the well construction coordinator. I appreciate all your patience. Thank you Sincerely, John Pearch, L.H.G. (#1410) Hydrogeologist and Well Drilling Coordinator Southwest Regional Office - Water Resources Program Department of Ecology PO Box 47775 Olympia, WA 98504-7775 Phone: 360-407-0297 Fax: 360-407-6305 Email: JOPE461 @ecv.wa.qov 2 !l Department of Ecology December 4,2009 Hydrogeologic Memo Part I: Chloride Sampling in Coastal Domestic Wells on the Black Point Peninsula, Jefferson County, Washington, pertaining to Water Right Application G2-30436 To: Phil Crane (Ecology) From: John Pearch, L.H.G (#1410) ,7/^ft44 fM P*,"hfE c Abstract The Black Point Peninsula (Peninsula) is a small peninsula along the western side of Hood Canal in Jefferson County, Washington. Due to increasing population growth, citizens are concerned about the sustainability of ground-water resources. A proposed development called the Pleasant Harbor Golf Course and Resort (Pleasant Harbor) has applied to withdraw groundwater from three production wells on the Black Point peninsula along the Hood Canal in southeastern Jefferson County. Pleasant Harbor applied to withdrawal an instantaneous quantity of 300 gpm and annual quantity of 239 acre-feet per year (afy), (131 afy for municipal use and 108 afy for irrigation use). The goals of this study were to: (1) evaluate the general extent of seawater intrusion; and (2) assess the need for future monitoring of groundwater levels and chloride concentrations. Seawater intrusion is not a widespread problem on the Peninsula, although there are two areas near the shoreline where it appears to be occurring in the Sea Irvel aquifer. Two wells in these areas have produced chloride concentrations exceeding 100 mg/L, a level indicative of seawater intrusion. Historical data in other wells show similar results. Specific conductance values in these areas were correspondingly elevated. Future periodic monitoring of ground-water levels, chloride concentrations, and specific conductance in select wells is recommended. Pearch, December, 2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peniruula Introduction This report describes the findings of an investigation of geology, groundwater quantity, ground- water quality, and seawater intrusion potential on the Black Point Peninsula, Jefferson County, Washington (Figure 1) This study was commenced for the purpose of processing a Ground Water Right Application G2- 30436 for Pleasant Harbor Golf Course and Resort and (Pleasant Harbor). Financial and staff support was provided by the Department of Ecology's (Ecology) Water Resources Program who conducted the majority of the work. Pacific Groundwater Group (PGG) also recommended field sampling of coastal wells and to proceed with this study. As required by RCW 90.44, all water right applications approved for groundwater withdrawals require a positive determination that: 1) water is available in the proposed wells, 2) the proposed wells do not impair existing rights or nearby wells, 3) the proposed wells do not impact surface water and 4) the proposed wells are not a detriment to the public welfare. Increasing chloride concentrations in nearby domestic wells as a result of seawater intrusion is a concern to many individual well owners and residents on the coast of the Black Point Peninsula. It was necessary to conduct this study to determine baseline chloride levels in existing coastal domestic wells in order to establish future groundwater monitoring for Pleasant Harbor. These results of this study allows Ecology to move fully review and recommend approval of Water Right Application G2- 30436 and give Pleasant Harbor appropriate provisions that pertain to water quality and water level monitoring. Specific mitigation measures will be identified to Pleasant Harbor in case their production wells increase chlorides levels in any monitoring wells. Purpose and Scope This study involved two days of ground-water sampling and analyses and measurement of groundwater levels. The purpose of this work was to: 1. Evaluate the extent of seawater intrusion in coastal domestic wells; 2. Provide requirements to Pleasant Harbor for future monitoring of groundwater levels and chloride concentrations; 3. Provide recommendations to Pleasant Harbor on the siting of future production wells and monitoring wells; 4. Provide recommendations to Jefferson County for updating the Seawater Intrusion Protection Znne (SPZ) map based on the results of this study. 5. Additional review by Ecology of Pleasant Harbor's monitoring requirements and the review of the aquifer test can be found in Pearch Hydrogeologic Memo Part II (2009). This study does not provide new estimates of the peninsula water-budget components, such as precipitation, surface-water runoff, evapotranspiration, ground-water recharge, and water use. It should also not be construed as a complete and detailed investigation of the hydrogeologic units, the quantity of water available for all future appropriations, or the full extent of seawater intrusion in water-supply wells on the peninsula. Page2 Pearch, December,2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula Regional Setting, Land Use, and Topography Black Point Peninsula is located in the northern portion of the Hood Canal, southeastern Jefferson County, about 3 miles south of Brinnon and 40 miles north of Shelton (Figure 1). The Peninsula is part of Water Resource Inventory Area 16 (Skokomish-Dosewallups). Access to the Peninsula is by U.S. Highway 101 or private boat. The Peninsula is primarily residential with a small marina on the north side. Much of the Peninsula was originally a campground area (formerly known as the American Campground), which is now owned by Statesman (the owner of the proposed Pleasant Harbor Resort and Golf Course). The primary groundwater users of the Peninsula currently have existing water rights, which include the Pleasant Tides Property Owners Association and exempt domestic wells. The surface area of the Peninsula is approximately 1.1 square miles (696 acres; area of the Peninsula east of Highway 101). The area owned by Statesman is approximately 0.34 square miles (220 acres) (Figure 1). The topography ranges from steep, coastal bluffs to gently rolling uplands. Most of the shoreline consists of steep bluffs with narrow beaches. The central portion of the Peninsula contains large surface depressions known as kettles. Kettles are landform features from the Vashon ice age that resulted in blocks of ice calving from the front of the receding glacier and becoming buried partially to wholly by glacial outwash. The Peninsula is bounded by saltwater on three sides, from Pleasant Harbor to the north, the Hood Canal to the east and the Duckabush River delta to the south. The ground surface elevation ranges from about 60 feet in the deepest kettle, to elevation 320 feet on a hill in the southeast portion of the site. The average site elevation of the Pleasant Harbor Resort is about 180 to 200 feet. Geology and Hydrogeology The geology of the Peninsula has been mapped by Dragovich et al. (2002) and Carson (1976). Subsurface Group (2008) have only mapped the surface geology on the Statesman property. The Vashon advance outwash (Qga "Quaternary glacial advance outwash") is mapped on parts of the Peninsula, with deposits are exposed along bluffs of the northwest, southwest and east-central portion of the Peninsula. The pre-Vashon glacial outwash deposit comprises most of the Peninsula and consists primarily of sand and gravel (Qgu) (Dragovich et a1.,2002). Both the Qga and Qgu units are important to the hydrogeology of the Peninsula because it forms what shall herein be called the Sea Level aquifer. Groundwater that is present within either of these units that make up the Sea Level aquifer are both in hydraulic continuity and considered the same body of groundwater. The Sea Level aquifer is unconfined due to the somewhat discontinuous nature of the overlying till. The Qgu unit is exposed along bluffs on the south eastern side of the Peninsula. However, there are no springs or seeps identified or sampled in this study. The top of the Sea Level aquifer is just a few feet above sea level on most parts of the Peninsula, whereas the aquifer base is well below sea level. Most wells tap this aquifer, but none penetrate the entire thickness. Similar to the pre-Vashon unit, this unit appears to be an unconfined aquiftr due to the somewhat discontinuous nature of the overlying till. Page 3 Pearch, December,2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula Other glacial deposits that are also present throughout the Peninsula include Vashon age recessional outwash (Qvr), Vashon ice contact glacial deposits (Qvi), Vashon basal till (Qvt), and continental glacial outwash (Qgo). The bedrock unit of the Peninsula is known as the Crescent Formation (basalt), located on the surface along its northern and east-central portions. However, it is not certain how deep the Crescent Formation extends below the surface, in the southern portion of the Peninsula. Wells have only penetrated the Crescent Formation on west of Highway 101 and indicate a separate aquifer that is disconnected from the Sea Level aquifer. Page 4 Pearch, December,2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula Bascd on U.S. Gcological Sun'ql - Brinmn Washin$on QLradranglc. I:21.(xX) (Map photo reviscd l9lt5) Contour Intcn al l() fect (NGVD 2.r) 1 a 101 E J I c *iryeia I st"t "*n 1PL.s.nt H.ftor) Prcp.rty N E S Figure lnset Map Location J+ R '- 'Glu.t..p polnt 1r, , y'' lrL / V,7 l,/ D- -z .-.),#ffr'r'' fi,.)' o- 0 0.25 0.5 Miles ,91 hurXif' 307!l**,r* Figure 1: Location and topography of Black Point Peninsula. Page 5 ) .t .+ 1 Pearch, December,2(X)9, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula Previous Investigations Many wells on the Black Point Peninsula have been sampled previously (Table 1, Appendix A and Figure 2). Walters (1971) and Dion and Sumioka (1984) sampled area wells during seawater intrusion investigations of Washington coastal aquifers. Ongoing monitoring for chloride (as required by the Washington State Department of Health- WSDOH) has been carried out by the Pleasant Tides Water System and also by domestic well owners (as required by Jefferson County Health Department). Groundwater is the primary source of potable water for residents of the Peninsula. Jefferson County building permit reports show chloride concentrations in water from wells varying from <5 mgll- to as high as 12,000 mgL. Although most wells were reported to have chloride concentrations to be < 5 mglL, those wells have been in production since the mid to late 1990s and may now have higher chloride concentrations as a result of more recent lateral seawater intrusion. Domestic Wells Based on the results of this study, domestic wells along the coast of the Black Point Peninsula have been reported to be at risk of seawater intrusion. These private domestic wells are located between the proposed Pleasant Harbor well and the Hood Canal shoreline. All domestic wells sampled in this study are completed between 20 feet above MSL to 228 feet below MSL (29 to 367 feetbelow ground surface - bgs) and typically withdraw small volumes of water (3 to 30 gpm). Some of the domestic wells were constructed with an open hole, where 7 of the wells were constructed with a screen. These nearby domestic wells are at risk of seawater intrusion due to their proximity to the coast and subsequently the freshwater/saltwater interface in the aquifer below. Additional pumping of the ACG well and additional proposed wells by Pleasant Harbor could cause this saltwater interface to move further inland, thereby increasing the risk of seawater intrusion in these wells. Pleasant Harbor Aquifer Testing and Well Construction Pleasant Harbor conducted an aquifer test in May, 2008 on the American Campground (ACG) well (Subsurface Group, 2008). However, even though chloride levels were reported as non- detectable in the aquifer test, Subsurface Group did not sample wells along the coast to determine if these wells could be at risk of sea water intrusion. As a result of this study, it was only necessary to sample chlorides in domestic wells without an additional aquifer testing of the ACG well. The ACG Well is located in the central portion of the Black Point Peninsula with Hood Canal surrounding it on three sides (See Figure 2).The ACG well was completed in July,1972to a total depth of 271 feet, approximately 2,100 feet inland from the southeastern shoreline of the Peninsula. The land surface elevation at the well head is 145 feet above mean sea level (MSL). According to Subsurface Group LLC (2008), the well is screened in the Pre-Vashon glacial deposit (Qu) from 215 to 270 feet below ground surface (bgs) (-70 ft to -125 ft MSL). In July, 2008 the static water level in the well was 136.1 feet bgs (8.74 ft MSL) (Subsurface Group, 2008). A second Pleasant Harbor production well has yet to be drilled, but was planned on the Page 6 Pearch, December,2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula southeastern portion of the Pleasant Harbor property, approximately 340 feet from the southern shoreline of the Hood Canal. Based on this study and PGG (2009), it is recommended that the second and possibly third well be located in SW % SE r/t Section 15, Township 25 North, Range 2 West W.M. A more detailed review on ACG aquifer test is found in PGG (2009), Subsurface Group (2008) and Pearch Hydrogeologic Memo Part II (2009). Well Numbering and Location System All wells that were monitored in this study that did not have a unique well tag (i.e., metal tags imprinted with a unique identification number) were affixed with a well tag to the casings or plumbing of the well. The unique identification number consists of three letters followed by three numbers (ex. AAB123). Table 1 (Appendix A) indicates the wells in which a new well tag was placed on the well. A map number also corresponds to well locations on the map in Figure 2. These well tags will enable future researchers to verify that they are visiting the same wells measured and sampled during this study. Pleasant Harbor will also be required to tag all existing and new monitoring and production wells. PageT LEGEND : Chloride /EC Monitoring VUell (with Map Numbeo I Static \,\Ater Le\€l only monitoring well A Hisorical Monitoring \,!blls Cl Seclion Number (within Township 25 Nodh, Range 2 Vvbst) ! Statesman - Pleasant Harbor property Moniloring wells Pearch, December,2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula Miles0 0.125 0.25 0.5 0.75 Figure 2: Monitoring well locations for sampling chloride and electrical conductivity (EC). Tidal Monitoring wells are wells that recorded continuous water levels with a pressure transducer (See Figure 9 and 10). Historical monitoring wells are approximate locations based on quarter quarter sections reported in Walters (1971). Page 8 I 07&08 \ \ \ \ Ed@\ I Pearch, December,2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula Methods The objectives of this study are outlined in a Quality Assurance Project Plan (QAPP) (Pearch, 2009). The main focus of this study was to determine existing chloride levels in representative domestic wells along the coast of the Peninsula. This study involved a combination of fieldwork and office evaluations of historic water quality and groundwater level data. There are many additional well owners that could not be contacted and these wells were not sampled or measured. However, these wells are still considered at risk from sea water intrusion even though they were not sampled in this study. The following criteria were used as a guideline for selecting the 13 domestic wells to comprise the monitoring network for this study. However, as indicated, not all the criteria could be met. 1) All wells were located along the Hood Canal coast of the Black Point Peninsula (Figure 2). 2) All well owners granted access to their wells. 3) With the exception of two wells, all well log reports were available for each well. 4) All wells were completed in the sea level aquifer, within the same body of groundwater as the ACG well. 5) 10 wells were sampled for water quality analysis (chloride and conductivity). However, static water levels could not be accessed for four of these sampled wells due to limited well access. Additional nearby domestic wells were measured for static water levels. A groundwater potentiometric surface map was not produced because of the limited number of wells measured as well as the seasonal nature and tidal influence on groundwater levels, 6) 7 wells did not have previous chloride sampling as required by Jefferson County building permitting. 7) All wells did not have a water treatment device, such as a water softener or iron treatment system, or a large storage tank that was not bypassed during sampling. 8) All wells sampled were spatially distributed to maximize coverage of the Black Point Peninsula according the guidelines specified in the QAPP (Figure 2). The well network was monitored at least once during the two-day monitoring period in mid August, 2009. Network wells were sampled for field parameters (temperature, conductivity, and chloride) and laboratory parameters (chloride and conductivity). Measuring temperature and conductivity in the field provided an indication whether stabilization occurred during sampling. This study was conducted on the Peninsula in an attempt to gather data from wells in the sea level aquifer. Eleven well owners (some of which had two wells that were sampled) were contacted beforehand to schedule sampling visits. The purpose of the site visits was to accurately locate the wells, determine well head elevations, take static water level measurements, and obtain water samples. Discussions with well owners during the field visits brought to my Page 9 Pearch, December,2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula attention additional wells at risk of seawater intrusion, and they were added to the list of sampled wells. Aquifers can be influenced by tidal fluctuations in adjoining marine waters, resulting in variations in both water level and chloride concentration. Generally, wells that are affected by seawater intrusion and that are tidally influenced tend to exhibit higher chloride concentrations and water levels during higher tides. In an attempt to collect consistent data, wells that fell within Vz mlle of the marine shoreline were monitored (water sampling and depth to water measurements) during a higher tide stage. Field Methods During the field visits existing wells static water level depths were measured and groundwater samples were collected. More details for measuring ground water levels and sampling groundwater from wells are described in the QAPP (Pearch, 2009). Salinity parameters measured in the field included electrical conductivity (EC) with an EC meter, and chloride measured with a portable chloride field test kit (Hach Model 8-P). Water samples were sent to Ecology's Manchester Laboratory for chloride analyses. Two of the high chloride samples were also analy zed for conductivity. Accurate ground-water elevation (head) data is necessary for determining the extent of seawater intrusion. In this study, initial estimates of water level heads in the sea level aquifer were made using (1) measured groundwater levels and (2) wellhead elevations estimated from Llght Distance And Ranging (LIDAR). After the data was collected, a GIS map was developed to include the newly collected water quality data and static groundwater elevations (estimated by subtracting depth-to-water from LIDAR land surface elevations). Well head locations and elevations were determined using a GPS Trimble GeoXT unit. This unit typically has accuracies of less than three feet for each point taken. However, the elevation (vertical) readings on this unit are considered less than adequate. Therefore, the latitude and longitude coordinates obtained from the GPS unit and field observations were matched with LIDAR data in GIS to obtain a elevation of the well head (in feet above mean sea level (MSL - datum in NAVD 88). All well elevations are based on LIDAR data derived from the Puget Sound LIDAR Consortium (2002). The distribution of chloride levels and groundwater elevations were interpreted with respect to well location, design and available hydrogeologic information (e.g. well logs, surficial geology and previous hydrogeologic characterization) to better understand the conditions that might contribute to any elevated chlorides in domestic wells along the coast of the Peninsula. Mechanisms of Seawater Intrusion Seawater intrusion is a water-supply concern along the Hood Canal. Coastal aquifers, such as the Sea l,evel aquifer, are hydraulically connected to the adjacent marine water body (Ecology, 2001). Consequently, they contain both fresh and saline (salty) ground water. Fresh ground water Page 10 Pearch, December,2009, Hydrogeotogic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula normally flows seaward within coastal aquifers, eventually intercepting saline ground water. The lighter, fresh water (l gram per cubic centimeter - g/cml) tends to override and "float" on the denser, saline water (1.025 g/cm:), but mixing also occurs. This mixing zone is known by several niunes, including the "freshwater-seawater interface," the "zone of transition," and the "zone of diffusion" (Figure 3A). The zone of diffusion is typically located near the marine shoreline. The exact location depends on several conditions, including the volume of freshwater discharge and the nature ofthe aquifer (confined or unconfined). In a typical coastal aquifer, the zone of diffusion dips down beneath the land surface (Figure 3A). In the case of an island or peninsula, the zone of diffusion can extend beneath the entire land surface (Figure 4). As with most aquifers, coastal aquifers are recharged primarily by precipitation. Under natural conditions, aquifer recharge is in equilibrium with ground-water discharge. Consequently, the zone of diffusion maintains a position of relative stability, moving slightly landward or seaward in response to varying climatic and tidal conditions (Figure 4). When ground water is pumped from coastal aquifers, freshwater that would normally discharge to the sea is intercepted, disrupting the natural equilibrium. This causes the zone of diffusion to migrate landward and/or locally upward. Ground water drawn into pumping wells can become increasingly saline (Figure 38 & 3C). Over time, the water can become unfit for consumption. This is especially true for wells located near the shoreline, on islands, and/or on peninsulas. The Ghyben - Herzberg relation gives an approximate location of the transition zofle - one foot of freshwater head above sea level indicates 40 feet of freshwater below sea level - with the assumption that the transition zone is a sharp interface. The boundary defined by this relation represents the center or 50 percent concentration of seawater within the transition zone. (Figure 5). However, based on PGG (2009) a ratio of 1:50 may be more appropriate for the Hood Canal as its water is slightly less saline. When considering seawater intrusion the Ghyben -Herzberg relation is very valuable, but it does not give the potential for contamination by the leading edge of the transition zone. Therefore, the goal is to protect wells from the leading edge of the transition zone. As the coastline is approached, the depth of the interface is greater than that predicted by the Ghyben - Herzberg relationship (Bear, 1987), thus the Ghyben -Herzberg relationship should provide a safe, conservative estimation of the location of leading edge of the wedge. Based on available data, a conservative assumption has been made that the thickness of the Sea Level Aquifer at the coastline is about 225 feet, ranging from sea level to -225 feet MSL. Using the Ghyben - Herzberg relation with this assumption results in a finding that a static water level of 4.5 feet MSL at the coastline would prevent the freshwater - seawater interface from migrating landward past the coastline. This water level at the coastline also should protect coastal wells, the deepest of which is completed at a depth of about -85 feet MSL (not including the well ACY954). In order to protect coastal wells from saltwater intrusion, there should be an absolute minimum average water level allowed at the coastline. At 2.9 feet, the theoretical sharp interface will be at -145 feet MSL and the leading edge will be at some higher elevation. If the aquifer is 225 feet thick as assumed, this could allow, in the worst case, the bottom 80 feet of the aquifer to be Page 11, Pearch, December,2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula contaminated at the coastline, but should still protect coastal wells. Movement of the wedge inland will be arrested where water levels in the Sea Level Aquifer reach 4.5 feet MSL, assuming the aquifer is 225-feet thick. Seawater intrusion on Black Point Peninsula is discussed in this report under "Water Quality." Page 72 Well A Seawater 1\ Zone ol Fresh ground water Saline ground waler Not to ealg nsitio n t scs Pearch, December, 2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula Nonpumping well in an unconf ined (water-table) aquiler under condilions ol equilibrium--no intrusion has occurre Well pumping Irom an unconf ined (water-table) aquiler-- seawaler intrusjon nol affecting salinity of pumped water Well pumping from an unconfined aquifer--seawater intrusion allecting salinily of pumped water. = Figure 3. Conceptual diagram showing how seawater intrusion can occur due to pumping of wells (from Orr, 2000). Figure 4. Conceptual diagram showing the relationship between fresh and saline ground water in a homogenous unconfined island aquifer. Fresh ground water flows both outward and upward while the zone of diffusion shifts seasonally (from Orr,2000). Figure 5. Conceptual diagram showing the Ghyben-Herzberg relation - that fresh ground water theoretically extends 40 feet below sea level for every foot it extends above sea level (from Orr, 2000). Sa bvd @cld Y/atq talYe: Whld (.krutryi kLo $rrrrs (Sr{lsraH) l.o:bsrb USGS FIos g,dra, Salha !rNld @tor Sallne 0rsutdutd ArNtu dENIB ct@tion o, grord-EEr l@BPum well Seawaler *g4t- \ lSt b $alc Fresh ground uiatet Saline ground water c well Seawater yy- Not to sde "dg Fresh ground waler Saline ground wat er \ Well t_ Sea- waler FeelneSali dgr0un Iwater Not lo scale USGS Page 13 Soa loval Sea level Zone ol t Waler table Fresh ground waler Zone ol Pearch, December,2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula Water Quality sampling for Chloride Chloride (Cl-) is one of the major inorganic ions in water. Chloride concentrations are measured in milligrams of chloride per liter of water (mg/L). Chloride in ground water can come from contamination by seawater, brines, leaching of marine sedimentary deposits, and domestic, agricultural, or industrial pollution (Ecology, 2001). Pure seawater contains about 35,000 mg/L of dissolved solids and approximately 19,000 mg/L of that is chloride (Hem, 1985). Chloride concentrations in the Puget Sound are slightly less due to dilution by freshwater inflow. ln northern Puget Sound, the concentration of chloride in seawater has been measured between 14,000 mgil (Sapik, et al., 1988) and 17,600 mg/L (Culhane, 1993). Southern Puget Sound probably contains slightly less chloride because it is farther from the Pacific Ocean and is more subject to the influence of freshwater inflow. No actual measurements of chloride concentrations in the Hood Canal were available. Fresh ground water typically contains less than 3O mglL chloride (Ecology, 2001). The water quality standard for chloride is 250 mglL. This is a secondary drinking water standard, based primarily on aesthetics (taste) and other factors as opposed to human health risks. Chloride concentrations above the 250 mg/L MCL begin to make water taste salty and the related sodium can be a health hazard to people requiring a low salt diet. Elevated chloride concentrations can also corrode metallic pipes and cause salt damage to plants. In coastal areas, a chloride concentration of 100 mg/L or greater in ground water is considered to be a red flag with respect to seawater intrusion. Aquifers located at or below sea level are susceptible to seawater intrusion. This would be true of the Sea Level aquifer on the Black Point Peninsula. Ten wells screened or completed in the Sea Level aquifer were sampled for chloride (Figure 6; Appendix A Table 3). More details on individual water wells sampled can be found in Appendix B. Chloride concentrations ranged from2 to 3500 mg[L, with a median of 3.23 mglL. Of the 10 wells sampled, five had chloride concentrations exceeding the assumed conservative background concentration of 4.86 mglL (Appendix A Table 3). Based on a geometric mean of the 8 samples that had chloride levels less than 26.8 mglL, background concentrations in wells along the coast is 4.86 mg/L. This background concentration is limited since it represents only 8 samples from one sampling period. However, this background concentration will be updated as Pleasant Harbor continues to monitor chlorides in coastal wells on the Black Point peninsula. Wells that exceeded the background concentration were located on the southwestern portion of the Peninsula, near the mouth of the Duckabush River, along Robinson Road. Chloride concentrations in two of these wells exceeded 100 mgfi-. These wells were ACY954 and BBB052 (Appendix A Table 3). The chloride concentration in well ACY954 exceeded the MCL of 250 mg/L (Washington State Department of Health drinking water standards) during the August, 2009 sampling period. This domestic well was analyzed for chloride at 3,500 mg/L. (See Appendix B for more description of sampling from each domestic well). Page 14 Pearch, December,2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula Unfortunately, none of the wells originally sampled by Walters (1971) and Dion and Sumioka (1984) were available for sampling during this study. However, in contrast, the four elevated chloride wells were at a different location on the Black Point Peninsula from the sampling of Walters (1971) when elevated chloride concentrations in Sea Level aquifer were found. Historical and current elevated chloride concentrations are summarized in Figure 6. Well depths and chloride concentrations in both the historical wells and the current wells are similar. None of the wells with elevated chloride concentrations have histories of large water withdrawals (all less than20 gpm).Therefore, these elevated chloride concentrations could be attributable to the close proximity of the well intakes to the natural zone of diffusion (saltwater upconing), rather than significant landward migration of the zone of diffusion (lateral intrusion). In addition, recommendations to Jefferson County to update the Seawater Intrusion Protection Zone (SIPZ) Ordinance No 09-0923 -02 can be found in Appendix C. Specific Conductance Spectfic conductance (or electrical conductivtty) is a measure of the ability of water to conduct electricity. Specific conductance is proportional to the concentration of dissolved solids in water, It is measured in microsiemens (prS) or micromhos (pmho) per square centimeter (cm'). Specific conductance is a secondary (aesthetic) contaminant. The drinking water standard for specific conductance is 700 pmho/cm'. In the case of seawater, dissolved solids include salts such as sodium chloride, magnesium chloride, or potassium chloride. Seawater contains roughly 35,000 mgll- of dissolved solids. The specific conductance of pure seawater is roughly 50,000 pmho/cm'. Specific conductance measurements can determine whether elevated chloride concentrations in ground water are due to seawater intrusion or other causes, such as connate water. Generally, higher specific conductance readings are indicative of seawater intrusion. There is often a roughly linear relationship between chloride concentration and specific conductance: the higher the chloride concentration, the higher the specific conductance value. By plotting chloride concentration against specific conductance data from a particular geographic area, a correlation coefficient (R') can be derived. The higher the correlation coefficient, the more reliable the relationship between chloride concentration and specific conductance. Dion and Sumioka (1984) found correlation coefficients ranging from 0.45 (poor) to 0.97 (excellent) in Washington coastal counties during their investigation of seawater intrusion. Data from the current study produced a correlation coefficient of 0.73 (Figure 7), which is considered good. Specific conductance in the Sea Level aquifer ranged from 1 12 to 10,300 pmho/cm'with a median value of 201 pmho/cm' (Appendix A Table 3). Two wells consistently exceeded the MCL for specific conductance - ACY954 and BBB052 on the Peninsula. These wells also produced elevated chloride concentrations. Page L5 LEGEND .: Chlorklo Concontration (rng/L) taken in August, 2009 A Historical Chlorile Concentration (rE/L) f] Seaion Number (within Township 25 North, Range 2 \ hst) I st.t .rrn - Pleassnt Harbor property Pearch, December,2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula Miles0 0.125 0.25 0.5 0.75 1 Figure 6: Chloride concentrations sampled in coastal domestic wells in August, 2009 and other time periods (see specific historical dates). See Figure 2 for corresponding map numbers and Appendix A Table 4 for corresponding Ecology Well Tag ID and Latitude/Longitude coordinates. Page 16 I \"1 / (1 26.8 ):: E \ I =iF \ \]@ A Pearch, December,2009, Hydrogeologic Memo Part Ir Chloride Sampling in Domestic Wells on Black Point Peninsula Chloride vs. Conductivity in Black Point coastal wells 10000 a 3s00 1000 892 E I 100 '=IE I R2 = 0.7266 5000 S p€cific C onductance (gmho,ibmr) elf ,%., 10 5.25 4 3.23 2-2.55 0 2000 4000 8000 10000 12000 FigureT: Linear regression between chloride concentration and specific conductance in the Sea Irvel aquifer (R2 - 0.7266).Individual chloride samples are labeled accordingly. All wells had static water levels less than 5.3 ft MSL. Static Water Level Monitoring in Coastal Wells Static water levels were measured in the 12 coastal domestic wells during the August, 2009 site visit. The average static water level elevation at the coastline is approximately 3.5 feet above MSL. However, due to deficiencies in surveying equipment and potential nearby pumping in nearby wells, we do not have great confidence in the accuracy of the static water levels. Therefore, the static water levels in coastal domestic wells should be better defined by Pleasant Harbor. Comparing Water Levels and chloride concentrations in wells This study attempts to further evaluate sea water intrusion on Black Point peninsula based on recommendations made by Kelly (2005). The water level elevation data was used as a tool for determining seawater intrusion risk on a site specific basis as specified in the QAPP (Pearch, 2009). However, different from Kelly (2005), this study did not evaluate water level elevation data to interpret intrusion susceptibility throughout the entire Black Point Peninsula. Page 77 Pearch, December,2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula According to Kelly (2005), the evaluation of water level elevation data as a seawater intrusion tool can be approached in several ways. One method involves comparing intrusion (or lack thereof) from the perspective of water chloride concenffation (chemistry) to the water level elevation data. However, there are problems associated with the use of chemistry for evaluation of seawater intrusion. These problems complicate the use of chemistry as a tool for validation of the water level elevation methodology for seawater intrusion analysis. Several different methods were utilized in this analysis of the chemistry data. The most simple of these methods was simply comparing chloride concentrations to water level elevations as shown in Figure 8. Compared to other seawater intrusion studies (such as Kelly, 2005), this study did not have any "false positives" where there are elevated chlorides that are not due to seawater intrusion. All of the sampled wells in this study had static water levels less than 8 feet MSL (Appendix A Table 2). Increased chloride levels that are indicative of "False positives" are typically found in wells that are impacted by very hard groundwater or failing septic tanks and are not caused by conventional seawater intrusion. The two wells with high chloride were positive sea water intruded wells. In addition, Kelly (2005) also demonstrates how using chloride concentration (chemistry) as a tool to evaluate risk for seawater intrusion may show intrusion is occurring (excluding the problems with false positives discussed previously), but it cannot evaluate if intrusion is likely to occur in the future. In essence, chemistry is a not a predictive tool; it cannot predict that intrusion will occur in the future. Instead, chemistry is a reactive tool, capable only of indicating intrusion once it begins to occur, in some cases too late to prevent significant degradation of groundwater quality. Page 18 Pearch, December,2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula Figure 8: Black Point Peninsula coastal domestic wells; chloride sampling on August 13 & 14,2009. \WcllMp No. ACG Well {SWL =9 ft msl from 2008} NS2. t: 08 a7 26. 25. t' ,t.rell E,tint .l -rti r Le . t I Elt . :rtr,,r, 100 ft -------SeaLevel -100 ft - -200 ft MSL t ,.--- ? 5.25 892 -3:23- ns 2.18 2.r3 2.0 Chloride Concentration (m 3500 Static water level (SWL) taken 8/09 (unless specified - see Table 1) ? = well extent or SWL is not certain Red numbers indicate exceeded background chloride concentration. (>5 mg/L) NS = no sample in ACG well taken in August, 2009 (only in Subsurface Group, 2008) 13* = Western Water Services sampled 8ll0l09 Vertical datum = Mean Sea Level (MSL) is in NAVD 88 10 13. Horizontal Scale Page 19 0'l N -'/ I 2.31 / Pearch, December,2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula Tidal Effects Aquifers that are hydraulically connected to seawater bodies are influenced by tidal cycles (Ecology, 2001). Heads in these aquifers are higher during high tide and lower during low tide. There is typically a lag time between high or low tide and corresponding high or low water levels in a well, respectively. Lag time is dependent on distance of the well from the shore and transmissivity of the aquifer. The more transmissive the aquifer or water-bearing zone, the shorter the lag time. It is useful to know the extent of tidal effects in an aquifer so that these effects can be filtered out of any water-level data collected. Tidal cycle monitoring was conducted in two wells on Black Point Peninsula to estimate the degree of tidal effects from Hood Canal, particularly in the Sea Level aquifer (Figure 9 and 10). The wells were continuously monitored (5 minute intervals) for a period of one week each. This time interval was chosen to encompass at least one tidal cycle. Two wells in the Sea Level aquifer were monitored for tidal influence. These measurements were compared to the nearest verified tidal data, gage9444900 at Port Townsend. This tidal data is for a location too far north of Black Point Peninsula to calculate accurately the lag time between tidal cycles and water-level fluctuations. However, the general association between tidal cycles and water levels is evident. This tidal data was converted from Mean Tide Level to MSL. As expected, tidal influence was evident in the two Sea Level aquifer wells. Well BBB054 is located on the southwestern shore of the Peninsula, about 5 feet from the bulkhead along the shore of the Hood Canal. The well's completion depth is -18 feet MSL. There was some pumping interference in the data, but tidal effects were still discernable .ln aZ4-hour monitoring period, approximately 5 feet of change was noted due to tidal influence (Figures 9). Well BBB051 is located on the north central portion of Black Point Peninsula, about 460 feet from the Hood Canal. Its completion depth is -47 feet MSL. There was some pumping interference in the data, but tidal effects were still discernable. Approximately 0.25 feet of change was noted due to tidal influence (Figures 10). Summary and Conclusions Chloride concentrations are within acceptable limits in most domestic wells on Black Point Peninsula, with the exception of one area in the Sea lrvel aquifer - the Robinson Road vicinity (SW of the Pleasant Harbor ACG well)). Well ABA1 12 (NE of the Pleasant Harbor ACG well) displayed elevated chloride concentrations during drilling in 1998. However, this well was not sampled to verify if sea water intrusion was occurring in this area. It is not known whether the withdrawal of water from the ACY954 well has induced seawater intrusion or if it was originally drilled near the natural zone of diffusion. Regardless, all domestic wells on the Black Point Peninsula appear to be at risk of a lateral seawater intrusion and thus continuing to monitor chlorides in domestic wells is recommended. Owners of older wells have some legal recourse should the newer Pleasant Harbor wells exacerbate or initiate a seawater intrusion problem. Older withdrawals have senior rights and therefore cannot be impaired by newer withdrawals. Page20 Pearch, December, 2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula Based on the results of this study, water supplies along the coast of the Peninsula is limited. Specific provisions are established for Pleasant Harbor, if chlorides in coastal domestic wells increase as result of withdrawals from Pleasant Harbor wells. Additional requirements for Pleasant Harbor to monitor chloride, electrical conductivity and static water levels in their own monitoring and production wells can be found in Pearch Hydrogeologic Memo Part II (December, 2009). Monitoring Recommendations Ecology and Jefferson County have agreed that monitoring for chloride, electrical conductivity and static water levels is essential for ensuring that Pleasant Harbor will maintain an adequate water supply for the proposed Pleasant Harbor wells and for the existing domestic wells on the coast of the Black Point Peninsula. Ecology agrees to Pleasant Harbor's proposed Neighborhood Water Policy that is required in Jefferson County Ordinance 01-0128-08 (Appendix D). In Jefferson County's approval of the FEIS completed for Pleasant Harbor, Jefferson County has included Condition P, the Neighborhood Water Policy, which requires Pleasant Harbor to provide access to its water system by any neighboring parcels if salt water intrusion becomes an issue for neighboring wells on Black Point peninsula. Statesman proposed to expand and define terms of this policy as a condition of the water rights. Ecology has the following comments based on Pleasant Harbor's proposed Neighborhood Water Policy: If the initial mitigation measures stated in recharge areas (condition 2) or initial mitigation measures (condition 3) do not correct or resolve the salt water impacts detected by the monitoring program, Pleasant Harbor will offer at its cost sufficient mitigation and/or replacement water for potable water for any existing home on a well that has an increase in chloride levels as follows and under the following conditions: a) Ecology agrees that resident wells located on the Black Point peninsula must be within in the same aquifer as the Pleasant Harbor's wells in order to be covered by this neighborhood policy. Ecology recommends that all wells be included on the Black Point Peninsula as long as they are completed in the Sea level aquifer. c) Ecology also agrees that the well owner provides conclusive evidence that chloride levels have increased over chloride levels in the well prior to Pleasant Harbor's use of groundwater, and the data from the monitoring program is consistent with the increase in chlorides. The default standard that Pleasant Harbor will provide alternative water supply if chlorides in a well exceed baseline (pre-Pleasant Harbor groundwater use) by l5Vo that results in levels above 200 mglL; or levels increase by 307o that results in levels above 100 mg/L over a 12-month period. d) Ecology also agrees that Pleasant Harbor has the right to request additional evidence from the resident showing that the Pleasant Harbor groundwater withdrawal is the cause of the increase in chlorides if the increase is isolated to one well, the increase is likely caused by another problem, and the only reasonable water replacement is a new well. Condition 4 b) "The well has a well log, was constructed properly and in compliance with the regulations at the time it was constructed, and metered." Ecology agrees that the wells must be Page21- Pearch, December, 2fi)9, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula constructed in accordance with Chapter 173-160 and Chapter 18.104 RCW in order for Pleasant Harbor to sample their wells. However. Ecologv does not agree that metering be a requirement in order for domestic wells to be replaced by Pleasant Harbor. Ecology may require installation of source meters on domestic wells but not in this particular situation. Based on the above conditions, Ecology recommends Pleasant Harbor to sample chloride and electrical conductivity, twice ayear in April and August, in four coastal domestic wells in the first 5 years of the Permit. It is recommended that static water levels be measured and Pleasant Harbor pay for access ports in each of these wells in order to take adequate water levels without having to remove the well cap. Installing pressure dataloggers for measuring continuous water levels is also up to the property owner and arrangements made under the Neighborhood Water Supply Plan (per Jefferson County Ordinance 01-0128-08). The following are the recommended coastal wells to be included: 1 . Porter/Boling domestic well (BBB05 1) at 1 1 I 3 Black Point Road. 2. Black Point community domestic well (AGR712 ) at 2180 Black Point Road 3. Myhre domestic well (BBB054) at 248 Robinson Road. 4. Beattie domestic well (888056) at 442Cormorant Way. The following are Ecology's additional recommendations to monitor groundwater quality and water levels in domestic well: 1) Ecology does not require Pleasant Harbor to sample individual domestic wells. It is solely up to the current property owners to allow Pleasant Harbor to sample their wells. An agreement between the property owners and Pleasant Harbor should be established. Most importantly, Pleasant Harbor should establish a contact and rapport with each property owner before sampling any wells. Pleasant Harbor should maintain continuity between any changes in property ownership to maintain access to the wells. It is recommended Pleasant Harbor contact all domestic well owners who have wells completed in the Sea lrvel aquifer on the Black Point Peninsula, asking if they would like to be included in the monitoring network. 2) Ecology recommends that Pleasant Harbor contact any additional property owners that are not listed in this study to monitoring domestic wells completed in the Sea kvel aquifer. Any additional property owners have the right to be included in the monitoring network, as long as their well is in the Sea Level aquifer. 3) It is in the best interest of all well owners to work with Pleasant Harbor to allow them to monitor their domestic wells. Pleasant Harbor has agreed to supply freshwater potable water to any property or well owner that experience seawater intrusion (as stated in the Neighborhood Water Policy - Jefferson County Ordinance 01-0128-08). 4) If Pleasant Harbor receives permission from the property owner to measure static water levels from their wells, it is recommended that the property owner turn off the well approximately 6-8 hours prior to taking a water level reading. Static water level measurements should occur within one hour prior to sampling for chlorides and electrical conductivity (as specified above). Page22 Pearch, December, 2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula 5) Pleasant Harbor is recommended to follow these guidelines for measuring static water levels in domestic wells: Ecology, Standard Operating Procedures for Manual Well-Depth and Depth-to- Water Measurements http://www.ecy.wa.eov/proerams/eap/qa/docs/ECY EAP SOP O52ManualWellDepth&Depthto WaterMeasures v I 0.pdf 6) Pleasant Harbor is recommended to follow these guidelines for groundwater sampling for chloride and electrical conductivity: U.S. Geologic Survey, Revised 2006, Techniques of Water-Resources Investigations Book 9, Handbooks for Water-Resources Investigations National Field Manual for the Collection of water-Quality Data chapter A4. CoLLECTION OF WATER SAMPLES http ://water. us gs. gov/owq/FieldManual/ 7) Pleasant Harbor is recommended to develop a Quality Assurance Monitoring Plan that is similar to the QAPP developed in Pearch (August, 2009) and other similar related to groundwater sampling in wells near the Puget Sound. The SOP's specified above should also be included in the QAPP. Page23 Pearch, December,2009, Hydrogeologic Memo Part I: Chloride Sampling in Domestic Wells on Black Point Peninsula References Bear, J., 1987. Modeling Groundwater Flow and Pollution, Theory and Applications of Transport in Porous Media. D. Reidell Publishing Company. Boston, 414 pp. Carson, R.J., 1976, Preliminary geologic map of the Brinnon area, Jefferson County, Washington: Washington Division of Geology and Earth Resources, Open File Report 76-3, scale 1:24000. Culhane, Tom, 1993. High chloride concentrations in ground water withdrawn from above sea level aquifers, Whidbey Island, Washington. Washington State Department of Ecology, Open- File Technical Report 93-07 ,35 p. Dion, N.P. and Sumioka, S.S., 1984. Seawater intrusion into coastal aquifers in Washington, Washington State Department of Ecology, Water-Supply Bulletin no. 56, 13 p.,14 plates. Dragovich, J.D., Logan, R.L., Schasse, H.W., Walsh, T.J., Lingley, W.S., Jr., Norman, D.K., Gerstel, W.J., Lapen, T.J., Schuster, J.E., and Meyers, K.D., 2002,Geologic map of Washington- -Northwest quadrant: Washington Division of Geology and Earth Resources, Geologic Map GM- 50, scale 1:250000. Grimstad, P. and Carson, R.J., 1981, Geology and ground-water resources of eastern Jefferson County, Washington: Washington Department of Ecology, Water-Supply Bulletin 54, scale l:48000. Hem, J.D., 1985. Study and interpretation of the chemical characteristics of natural water (Third Edition). U.S. Geological Survey Water-Supply Paper 2254,263 p. Kelly, D., 2005, Seawater Intrusion Topic Paper, Island County / WRIA 6 Watershed Planning Process Orr, Laura, 2000. Is seawater intrusion affecting ground water on Lopez Island, Washington, U.S. Geological Survey Fact Sheet FS-057-00, 8p. Pearch, J., August, 2009, Quality Assurance Project Plan, Sampling for Chlorides in Wells on the Black Point Peninsula, Pearch, J. December,2009, Hydrogeologic Memo Part II, Pleasant Harbor Monitorino requirements and aquifer testing review. Puget Sound LIDAR Consortium,2002 Pacific Groundwater Group (PGG), June 4, 2009, Technical memorandum, Pleasant Harbor Modeling Analysis, To Phil Crane, Ecology; From: Peter Schwartzman, PGG Page24