Attachments_4_2022_Semi-Annual_GMR_New_Melones_Glory_Hole_0001.pdf

Glory Hole Recreation Area

Wastewater Treatment Facility (WWTF)

2022 Semi-Annual Groundwater Monitoring Report

California Regional Water Quality Control Board

Central Valley Region Revised MRP No. 2014-0153-DWQ-R5273

Pond 2 Pond 1

View looking southeast

Prepared for:

U.S. Bureau of Reclamation Central California Area Office

7794 Folsom Dam Road Folsom, California 95630

Prepared by:

2737 North Main Street, Suite 200 Walnut Creek, CA 94597

July 2022

2022 Semi-Annual Groundwater Monitoring Report

Glory Hole Recreation Area Wastewater Treatment Facility (WWTF)

California Regional Water Quality Control Board Central Valley Region

Revised MRP No. 2014-0153-DWQ-R5273

Prepared for:

U.S. Bureau of Reclamation – Central California Area Office 7794 Folsom Dam Road Folsom, California 95630

Prepared by:

2737 North Main Street, Suite 200 Walnut Creek, CA 94597

Alisto Project No. 13-053-004

July 2022

Hamidou Barry, P.G. Al Sevilla, P.E.

Project Geologist Principal

July 14, 2022

This document was prepared by Alisto Engineering Group (Alisto) under the supervision of the licensed professional whose signature appears below. No warranty, either expressed or implied, is made as to the professional advice presented in this document. Any data analysis, conclusions, and recommendations contained in this document are based upon site conditions at the time of the investigation. Site conditions are subject to change with time, and such changes may invalidate the interpretations and conclusions in this document.

The conclusions presented in this document are professional opinions based solely upon the interpretation of information available as described herein. The reader should note that the scope of this project was limited and may not be appropriate to satisfy the needs or requirements of other potential users, including public agencies not directly involved.

Signed

Hamidou Barry, P.G.

California Professional Geologist, No. 9172 ii

Table of Contents

1.0 EXECUTIVE SUMMARY

2.0 BACKGROUND

3.0 GEOLOGY AND HYDROGEOLOGY

4.0 GROUNDWATER QUALITY STANDARDS

5.0 UP-GRADIENT (BACKGROUND) GROUNDWATER QUALITY

6.0 WASTEWATER TREATMENT PLANT OPERATOR CERTIFICATION

7.0 WATER SUPPLY WELL MONITORING

8.0 INFLUENT MONITORING

9.0 LAGOON (POND) MONITORING

10.0 DISPOSAL OF SLUDGE AND/OR SOLID WASTE

11.0 SPRAY FIELDS STATUS

12.0 FIRST SEMI-ANNUAL 2022 GROUNDWATER MONITORING

12.1 Groundwater Depths, Elevations and Gradients

12.2 Groundwater Migration

12.3 Well Purging and Sampling Procedures

12.4 Laboratory Analytical Data

12.4.1 Semi-Annual Constituents

13.0 GROUNDWATER MONITORING TRENDS

13.1 Groundwater Depths and Elevations, Gradient and Gradient Direction

13.2 Analytical Trends

14.0 CORRECTIVE ACTIONS

15.0 SUMMARY AND CONCLUSIONS

15.1 Water Supply Monitoring

15.2 Influent Monitoring

15.3 Lagoon (Pond) Monitoring

15.4 Pond Sludge

15.5 Spray Fields

iii

15.6 Groundwater Monitoring

15.6.1 Up-Gradient (Background) Groundwater Quality

15.6.2 Depth to Groundwater and Groundwater Gradient

15.6.3 Analytical Results

15.7 Recommendations for No-Purge Sampling

FIGURES

1 Vicinity Map 2 Location Map 3 Relief Map 4 Site Map 5 Monitoring Well Location Map (oblique view) 6 Regional Geologic Map 7 Transect A-A′ 8 Diagrammatic Cross Section A-A’ 9 First Semi-Annual 2022 Groundwater Potentiometric Elevation Contour Map (March) 10 Diagrammatic Figure Showing Hypothetical Migration of Wastewater from Ponds along

Subsurface Fractures to a Point Up-Gradient of Ponds

TABLES

1 Groundwater Monitoring Well Construction Details 2 Groundwater Monitoring Well Laboratory Analyses Requirements 3 Currently Established and Recommended Groundwater Limitations 4 Depth to Groundwater Measurements and Calculated Groundwater Elevations 5 Groundwater Monitoring Wells – Semi-Annual Laboratory Results

CHARTS

1 Groundwater Elevations (monitoring wells) 2 GH-Background Groundwater Elevations 3 GH-MW1 Groundwater Elevations 4 GH-MW2 Groundwater Elevations 5 GH-MW4 Groundwater Elevations 6 SF-Background Groundwater Elevations 7 SF-MW1 Groundwater Elevations 8 SF-MW2 Groundwater Elevations 9 SF-MW3 Groundwater Elevations 10 GH-MW1 – Electrical Conductivity (EC) 11 GH-MW1 – Total Dissolved Solids (TDS) 12 GH-MW1 – Total Coliforms 13 GH-MW2 – Total Dissolved Solids (TDS) 14 SF-Background – Total Coliforms 15 SF-Background, SF-MW1 and SF-MW3 – Total Coliforms iv

APPENDICES

A Photographs – Lift Station #8, Ponds, Wells B Drawing 881-D-47 (As-Built Lagoons) and Drawing 881-D-50 (As-Built Spray Fields) C WWTF Operator Certification D Groundwater Monitoring Wells – Purging and Sampling Logs E Laboratory Analytical Report, Chain of Custody Form and Quality Control Report

1.0 EXECUTIVE SUMMARY

This report documents and presents the results of the 2022 semi-annual groundwater monitoring performed at the Glory Hole Recreation Area Wastewater Treatment Facility (WWTF) at New Melones Reservoir. The semi-annual monitoring was performed during the first calendar quarter of 2022 in accordance with the new CVRWQCB MRP No. 2014-0153- DWQ-R5273 dated December 12, 2018. Groundwater samples were collected from the eight (8) groundwater monitoring wells on March 30, 2022.

Depths to groundwater in the eight monitoring wells were variable and ranged from approximately 0.2 to 7 feet shallower in comparison to the depths in the previous monitoring event (third Quarter 2021). The analytical results during first quarter 2022 were generally consistent with historical trends. Detected concentrations were similar to past monitoring events. Groundwater limitations (established and recommended) were not exceeded in the samples collected from wells GH-MW2, GH-MW4, SF-Background, and SF-MW1. Three semi-annual constituents (electrical conductivity, total dissolved solids and total coliforms) exceeded established groundwater limitations in one or more of the remaining wells. There were no deficiencies or violations of the monitoring and reporting requirements that required corrective action.

In previous monitoring events, US Bureau of Reclamation (Reclamation) voluntarily monitored wastewater (ponds and Lift Station #8) for select constituents on a monthly basis.

Concentrations in wastewater were compared to concentrations in groundwater to evaluate whether wastewater had the potential to impact groundwater quality. Based on the comparison, with the exception of TDS, wastewater did not contain sufficiently high enough concentrations to account for concentrations detected in groundwater.

The second semi-annual monitoring event (annual event) will be performed during the third calendar quarter of 2022 in accordance with the CVRWQCB MRP No. 2014-0153-DWQ-R5273.

Groundwater samples will be only collected from the eight (8) existing groundwater monitoring wells. MRP No. 2014-0153-DWQ-R5273 does not require monitoring or sampling the two (2) water supply wells (Primary Supply Well and Secondary Supply Well).

Recommendation: Reclamation is recommending the use of No-Purge Sampling technique for the semi-annual and annual events. It is recommended that No-Purge Sampling starts during the third quarter 2022 groundwater monitoring event.

2.0 BACKGROUND

The New Melones Reservoir is located in the Sierra Nevada foothills, approximately 65 miles southeast of Sacramento and 40 miles east of Stockton as shown on Figure 1. It is a multi-purpose reservoir owned and operated by Reclamation. The reservoir provides water storage for irrigation, flood control, hydropower, and recreation activities. Reclamation owns and operates a WWTF on the north side of the reservoir, which accepts wastewater from throughout the Glory Hole Recreation Area (Figure 2). The Glory Hole entrance kiosk is located on Whittle Road, approximately 2.1 miles south of the intersection of Whittle Road and Highway 49.

The WWTF’s ponds are located approximately 850 feet west southwest of the kiosk on a hillside approximately 350 feet above the reservoir’s normal operating water surface (Figure 3). The bottom of the ponds is at an approximate elevation of 1425 feet msl.

The WWTF began treating wastewater in 1984 from the Glory Hole Recreation Area, which serves two campgrounds, four (4) day use areas, and a marina concessionaire. Contributing sources of wastewater include restrooms, showers, fish cleaning stations, floating portable toilets, a RV trailer waste dump station, and a marina. Although, waste is currently not accepted from the RV trailer dump station and marina. The wastewater treatment system consists of a force main sanitary collection system and two wastewater treatment lagoons (ponds). Eight lift stations pump wastewater to the facility and the wastewater is discharged into Pond 1. Lift Station #8 is furthest downstream station (closest upstream station) to the ponds as shown on Figure 4 and Appendix A - Photos 1 and 2. Wastewater flows from Pond 1 to Pond 2 by an interconnecting weir (Appendix A - Photo 4). The ponds, which have a combined capacity of approximately 3.47 million gallons, are lined with an 80-mil HDPE membrane to prevent wastewater from percolating into the subsurface and promotes evaporation (Appendix A - Photo 5). Land application areas (two spray fields) were constructed east of the ponds for disposal of treated wastewater (Figure 4 and Appendix A - Photo 6); however, they have not been used since 2008 since the ponds have adequate capacity to achieve zero discharge through evaporation of wastewater. As-built drawings for the ponds and spray fields are included in Appendix B.

The CVRWQCB is the lead regulatory agency responsible for protecting beneficial use of waters of the State, and for mandating monitoring requirements for WWTF operations that have the potential to negatively impact waters of the State. The objective of the WDR/MRP is to establish a monitoring program for assessment of the impact of WWTF operations on the beneficial use of waters of the State. The current MRP issued for the Glory Hole WWRF requires weekly and monthly monitoring and reporting of influent and pond wastewater; and semiannual monitoring and reporting of groundwater. Influent samples are collected from Lift Station #8, pond samples are collected from the Pond 1, and groundwater samples are collected from eight monitoring wells and two drinking supply wells shown on Figures 4 and 5. The monitoring wells were installed in June 2003 and groundwater monitoring has been performed since July 2003. Monitoring well construction details are shown on Table 1. Groundwater monitoring includes: measuring depth to groundwater; purging; measuring pH, temperature, and electrical conductivity (EC) during purging; collection and laboratory analysis of samples, and semiannual reporting. Samples are analyzed for the specified list of constituents for the first semi-annual event and for the annual sampling event for the third quarter of each year during the peak recreational use of the Glory Hole Recreation Area. Table 2 lists the semi-annual and annual constituents to be analyzed per MRP No. R5-2002-0125 (Rev 2), dated April 30, 2013.

3.0 GEOLOGY AND HYDROGEOLOGY

New Melones Reservoir is located within the foothills of the Sierra Nevada geomorphic province, which is primarily composed of Jurassic age [approximately 145 to 200 million years (Ma)] igneous (granitic) and metamorphic (metasedimentary and metavolcanic) rocks as shown on Figure 6. Faulting uplifted the Sierra Nevada province approximately 4 to 5 Ma, tiling it westward.

The WWTF area is bounded by a series of northwest trending strike-slip faults of the Melones Fault Zone and Bear Mountains Fault. The ages of the faults range from Late Quaternary (less than 700,000 years) to pre-Quaternary (greater than 2.6 Ma). Faulting has tilted and folded some of the geologic units, resulting in numerous anticlines and synclines throughout the region (Figure 6).

Geologic logs of drill holes advanced at the site, in which the monitoring wells were installed in, indicate a thin surficial layer of Quaternary-age clayey soil and/or colluvium is present to depths between 1 and 8.5 feet. The soil/colluvium is underlain by Jurassic-age rock consisting of two major rock groups: fractured and foliated metasediments (slate) and metavolcanics (greenstone). The type of rock at a particular location varies with depth and may be controlled by faults and/or folding. For example, greenstone is underlain by slate at monitoring well GH- MW1; however, the opposite occurs at monitoring well GH-MW2. First groundwater was encountered in fractured and foliated (parallel alignment of the rock structure) rock at depths between 17.5 to 139 feet during drilling. Static/equilibrated groundwater has ranged from artesian (approximately 1 foot above ground surface in SF-MW2) to approximately 150 feet below ground surface (bgs) in GH-MW1. Based on well development and sampling, groundwater recovery is low in all but well GH-MW4. Recharge in most wells range from less than 1 gallon per minute (gpm) to 3 gpm. Recharge in GH-MW4 is estimated to be about 20 gpm. Groundwater gradient directions are generally opposite to perpendicular of topography.

The orientation and continuity of fractures and foliation are unknown, but likely play a major role in controlling groundwater conditions at the site. Other undocumented geologic features such as faults and folds may also control groundwater conditions.

A diagrammatic cross section was prepared along a nearly east to west aligned transect that bisects the site (Figures 7 and 8). The objective of the section is to illustrate the normal reservoir water surface elevation, general topography, general geologic conditions, well screened intervals, and depths to groundwater. The following discussion summarizes information shown on the section:

The WWTF is located in a saddle between two ridge lines (Appendix A - Photo 7). A seasonally flowing creek is located at the low point of the saddle, which drains southerly into the reservoir.

The ponds are on a hillside that slopes toward the east. The normal reservoir water surface elevation is approximately 350 feet below the bottom of the ponds. The spray fields are located on a hillside that slopes toward the west.

Monitoring wells are screened in fractured rock and extend to depths between approximately 27 and 150 feet, or approximately between 48 and 136 feet below the bottom of the ponds. The top of wells screens are between approximately 27 and 115 feet below the bottom of the ponds.

Table 1 provides a summary of additional well construction details. Photos 4 and 6 through 12 in Appendix A show the well locations. The groundwater gradient is generally opposite of topography and is steep, ranging in depth between approximately 40 and 110 feet directly below the ponds. The groundwater gradient is generally perpendicular (mimicking topography) and gentler east of the ponds and beneath the spray fields.

4.0 GROUNDWATER QUALITY STANDARDS

The constituents to be analyzed in groundwater samples as set forth in MRP No. 2014-0153- DWQ-R5273 are listed in Table 2. The WDR provides the maximum allowable concentrations (limitations) for some of the constituents as listed in Table 3. The CVRWQCB directed Reclamation to use drinking water quality goals or background water quality concentrations (whichever values are higher) as a basis for comparison for those constituents without limitations. Therefore, Reclamation used the State Water Resources Control Board’s “A Compilation of Water Quality Goals” online database to determine drinking water quality goals for those constituents that do not have limitations listed in the WDR as presented in Table 3.

Constituents that do not have published federal or state drinking water quality goals include sodium and zinc.

5.0 UP-GRADIENT (BACKGROUND) GROUNDWATER QUALITY

An exceedance of a groundwater quality standards does not necessarily indicate that wastewater has impacted groundwater quality. Up-gradient conditions, migration pathways, and geologic structure must also be considered in assessing impact on groundwater quality.

Constituents with elevated concentrations can be naturally occurring and/or the result of up-gradient activities.

The monitoring wells are screened at elevations that are lower than the bottom of the ponds;

therefore, the wells have varying degrees of probability to intercept wastewater if the ponds were to leak. Wells SF-Background and SF-MW3 were installed at a distance from the ponds for groundwater in the wells to be considered representative of background water quality. Well SF-Background is located approximately 650 feet northeast of Pond 2 and Well SF-MW3 is located approximately 300 feet north-northeast of Pond 2. Both wells of are located hydraulically up-gradient of the ponds and constituents of concern are seldom detected in these wells at concentrations greater than their respective groundwater quality standards. As discussed in the Technical Report, dated December 1, 2012, Wells SF-Background and SF- MW3 would not likely intercept wastewater percolating into the subsurface from beneath the ponds and as such, are considered “background” or up-gradient wells.

6.0 WASTEWATER TREATMENT PLANT OPERATOR CERTIFICATION

In accordance with the MRP and Title 23, CCR. Division 3, Chapter 26, the operator’s certification is included in Appendix C.

7.0 WATER SUPPLY WELL MONITORING

A groundwater well designated as “primary well” is used to supply potable water to Glory Hole Recreation Area. A “secondary well” serves as a backup, if needed. These two (2) wells are located approximately 1,000 feet south-southeast of the wastewater treatment ponds as shown on Figure 4. The ground surface at the wells is approximately 50 feet lower than the bottom of the ponds. The wells are located hydraulically cross-gradient to down-gradient of the ponds. It appears that the drilling contractor who installed the wells submitted a Well Completion Report for only one of the wells to the Department of Water Resources (DWR) but the Report does not specify which well. The well completion report does indicate that the well was installed in November 2004 to a depth of 1,020 feet. The well is screened in fractured greenstone, and in underlying foliated schist.

The water supply wells are sampled monthly for total coliforms (county and/or state requirements). Monthly sampling is not a requirement of the WDR/MRP; therefore, the sampling results are not included in this report. Monthly sampling results were included in previous semi-annual and annual groundwater monitoring reports. Total coliforms were not detected in either well dating back to at least 2010.

In accordance with the WDR/MRP, the water supply wells were sampled annually for EC, pH, and standard minerals. Annual sampling was performed during the third quarter of each year when peak recreational use of the Glory Hole Recreation Area occurs. The CVRWQCB MRP No. 2014-0153-DWQ-R5273 dated December 12, 2018 does not require monitoring or sampling the water supply wells.

8.0 INFLUENT MONITORING

Lift Station #8 pumps wastewater into Pond 1 (Figure 4 and Appendix A - Photo 1). Lift Station #8 is sampled monthly and samples are analyzed for a variety of constituents. Monthly reports were submitted to the CVRWQCB.

In the past, the only constituents analyzed in both Lift Station #8 and monitoring wells was formaldehyde and total phenols. Analyzing for these constituents in pond samples assisted in evaluating whether wastewater contained sufficiently high enough concentrations to impact groundwater quality and account for concentrations detected in the wells. As required in the previously MRP (June 2010) formaldehyde and total phenols were first analyzed in influent samples from Lift Station #8 in July 2010. Unusually high concentrations of these two constituents were detected in samples from Lift Station #8 during first, second, and fourth quarters of 2013. The MPR dated April 2013 did not require formaldehyde and total phenols be analyzed in influent samples from Lift Station #8 (beginning in June 2013). However, Reclamation elected to voluntarily analyze samples from Lift Station #8 monthly for a two year period for these two constituents to evaluate whether elevated concentrations detected in 2013 were isolated occurrences. Elevated concentrations of these two constituents were not detected during the subsequent two years of monitoring.

9.0 LAGOON (POND) MONITORING

The WWTF lagoons (ponds) were monitored weekly (field parameter sampling and pond liner condition). The liners were reported as intact and in good condition. Monthly reports were submitted to the CVRWQCB.

Elevated concentrations of TDS, iron, and manganese are commonly detected in down-gradient wells GH-MW1 and GH-MW2. Reclamation voluntarily analyzed samples from Pond 2 for these constituents intermittently between July 2014 and June 2015 to assist in evaluating whether wastewater contained sufficiently high enough concentrations to impact groundwater quality and account for concentrations detected in the wells.

Due to the lack of water, GH-MW1 was only sampled once and GH-MW2 was only sampled twice between July 2014 and June 2015. Pond 2 was sampled eight times during this period.

Wastewater in the ponds contained high concentrations of TDS that could impact groundwater quality to account for concentrations detected in the wells. However, with the exception of August 2014, wastewater did not contain high concentrations of iron and manganese to account for concentrations detected in the wells. As such, Reclamation voluntarily ceased monitoring wastewater from Pond 2. Analytical results for Pond 2 sampling were included in the 2015 annual report.

10.0 DISPOSAL OF SLUDGE AND/OR SOLID WASTE

Sludge and/or solid waste has not been disposed of following installation of the pond liners in 2003. Photos 2 and 3 show accumulated sludge in the ponds on January 29, 2015.

11.0 SPRAY FIELDS STATUS

Wastewater disposal was accomplished by evaporation of the ponds; therefore, the spray fields were not used during first quarter 2022. The spray fields were last used in 2008.

12.0 FIRST SEMI-ANNUAL 2022 GROUNDWATER MONITORING

Alisto Engineering Group (Alisto) performed the semi-annual groundwater monitoring on March 30, 2022. Findings of the semi-annual monitoring event are presented in the following sections.

12.1 Groundwater Depths, Elevations and Gradients

Depth to groundwater was measured prior to purging and sampling each well. Measurements were made on March 30, 2022 using a conductivity-based water level meter. The need to provide a snapshot of groundwater elevations in all wells prior to any purging and sampling was not necessary due to the use of low flow purging that minimized groundwater withdraw.

To reduce the potential for cross contamination, the water level meter was cleaned and rinsed with deionized water, and new Nitrile gloves were donned between wells. Depth to water in each well was measured to the nearest 0.01 foot from the surveyed notch on the top of well casing. Measurements were recorded on groundwater sampling logs (Appendix D). Depths to groundwater were between 8.89 feet below ground surface (bgs) in SF-MW2 and 141.65 feet bgs in GH-MW1. Depth to groundwater measurements are summarized on Table 4.

The equilibrated groundwater surfaces in GH-MW1 and SF-MW1 were within the well screen intervals, and were above the well screen intervals for the remainder of the wells. The presence of groundwater in wells above the screened intervals suggests subsurface pressure exists and does not necessarily indicate groundwater is present in the subsurface at the measured depth.

Water enters a well through the screen and the measured depth to groundwater is considered a potentiometric surface that represents a depth that groundwater stabilizes at (in an open hole) once subsurface pressure and atmospheric pressure reach equilibrium.

Potentiometric elevations were calculated by subtracting depth to groundwater measurements from the surveyed top of well casing elevations. Potentiometric elevations varied by about 90 feet in the wells, between 1404.95 feet mean sea level (msl) (SF-Background) and 1314.80 feet msl (GH-MW2). Potentiometric elevations beneath the ponds were estimated to range from approximately 1388 (GH-Background) to 1315 feet msl (GH-MW1 and GH-MW2). The bottom of the ponds is at an approximate elevation of 1425 feet msl; therefore, the potentiometric surface was estimated to have been between approximately 37 and 110 feet beneath the bottom of the ponds. Using the rationale describing potentiometric elevations, the actual distance between the bottom of the ponds and groundwater may be greater than the distance between the bottom of the ponds and the potentiometric surface.

Figure 9 depicts potentiometric elevation contours, which represent groundwater pressure gradients and flow directions. The map shows contour gradients and gradient directions varied across the site. A north-south aligned and southerly draining seasonal creek bisects the site and is coincident with the change in groundwater gradient and gradient direction. The creek bed is located at the base of a hillside sloping toward the east (on which the ponds are located) and a hillside sloping toward the west (on which the spray fields are located).

Potentiometric gradient direction east of the creek bed and beneath the spray fields was approximately to the southwest with gradients of approximately 0.05-foot to 0.08-foot vertical drop per 1-foot horizontal distance. SF-Background was up-gradient of the spray fields, and SF-MW3 was cross-gradient to down-gradient of the northern spray field. GH-Background and SF-MW2 were down-gradient of the southern spray field, and SF-MW1 was cross-gradient of the spray fields. The spray fields have not been utilized since 2008.

The potentiometric gradient directions west of the creek bed and beneath the ponds were approximately to the west with steeper gradients of approximately 0.14- (Pond 2) and 0.22-foot (Pond 1) vertical drop per 1-foot horizontal distance. Groundwater gradients and gradient directions beneath the ponds were consistent with historical conditions. GH-MW1 and GH- MW2 were down-gradient of the ponds, GH-MW4 was cross-gradient of the ponds. GH- Background and each of the “SF” wells are considered up-gradient of the ponds.

12.2 Groundwater Migration

Accurately classifying wells as down-gradient, cross-gradient, or up-gradient of the wastewater ponds, requires an understanding of subsurface conditions. Geologic conditions control how groundwater migrates. Based on boring logs for the monitoring wells and the presence of rock outcrops adjacent to the ponds, the bottom of the ponds appear to be founded on fractured rock. Fractured rock is present throughout the entire site, beginning at depths between approximately 1 and 8.5 feet below ground surface (Figure 8). The body of the rock is mostly composed of interconnected mineral grains; therefore, the body of the rock does not contain substantial void spaces. The body of the rock is essentially impermeable, and groundwater migration and surface water infiltration likely occur only through the fractures. Fracture density, orientation, openness, and continuity are unknown.

It is common practice to assign wells as up-gradient and down-gradient based on a direct comparison of groundwater elevations to the feature being monitored. If groundwater is in direct contact with the feature, a direct comparison of groundwater elevation contours can be used to identify which of the wells can be designated as down-gradient, cross-gradient, and up-gradient of the feature. However, if a significant unsaturated zone exists between the feature being monitored and groundwater, migration of liquid from the feature can occur through the unsaturated zone to groundwater at a point up-gradient of the feature. The common practice is to directly compare, without consideration of migration pathways through the unsaturated zone, by projecting the feature’s footprint vertically to groundwater.

If there is leak in the ponds, wastewater is not be expected to vertically migrate within the footprint because of the fractured rock geologic setting. Instead, wastewater would likely follow various fracture pathways that are off-angle with respect to vertical, unless the leaking wastewater happens to be intercepted by a vertical fracture in the rock. These off-angle migration pathways could allow wastewater to migrate through unsaturated materials and into groundwater up- gradient of the projected vertical footprint. Between about 30 and 95 feet of unsaturated fractured rock exists between the bottom of the ponds and the underlying groundwater during various times over the years. It should not be assumed that some wells shown as up-gradient of the ponds are not susceptible to intercept wastewater that has hypothetically leaked from the ponds.

Wells located closest to the ponds would generally have a higher potential to intercept wastewater (if present) than wells located at greater distances from the ponds. Figure 10 shows a diagrammatic depiction of hypothetical migration of wastewater from ponds along subsurface fractures to a point up-gradient of the ponds. This may explain elevated concentrations of TDS and Nitrate as N detected in GH-Background in 2003 and 2004. The elevated concentrations may have been residual from leaks in the pond liners prior to liner replacement in 2003.

Groundwater gradient directions typically mimic surface topography. This is not the case at this WWTF site. The groundwater gradient direction is approximately opposite of topography beneath the ponds. Groundwater migration is controlled by fractures in rock, and possibly bedding planes or foliation. The fracture density (spacing between fractures) plays an important role in how groundwater moves through rock. Intensely fractured rock has closely spaced fractures that can be interconnected, allowing groundwater to migrate in many directions, similar to soil. Slightly fractured rock has further spaced fractures, which can control groundwater movement similar to pipelines. In fractured rock, the direction that groundwater moves depends on the orientation and continuity of the fractures, as well as other factors such as how open the fractures are and hydraulic pressure(s) in the fractures.

12.3 Well Purging and Sampling Procedures

Following depth to groundwater measurements and prior to sampling, water was purged from each well. A stainless steel submersible low flow pump attached to Teflon tubing was used to purge and sample the groundwater monitoring wells. The pump was placed at the approximate center-point of each well screen interval. Pumping rates ranged between 250 and 450 mL/min. To reduce the potential for cross contamination, the pump was triple rinsed with deionized water prior to use in each well. New Teflon tubing was used for each well. Nitrile gloves were donned between wells. Information collected during purging is shown on the purging and sampling logs (Appendix D).

Approximately 0.2 to 0.8 well volumes of water were removed from the wells. One well volume is defined as the volume of water (water column) in the well prior to purging.

Approximately 3 to 6 liters of groundwater were purged from the wells. Purging continued until field parameters “stabilized” as follows:

pH: +/- 0.2 units

Temperature: +/- 0.15o C

Specific Conductance: +/- 5%

Specific conductance in GH-MW1 was measured at 978 μS/cm, which exceeded the groundwater limitation of 900 μS/cm, but consistent with historical record.

Samples were collected from each well by filling bottles provided by the laboratory with water discharging from the Teflon tubing. Sample bottles were certified by the laboratory as clean sample containers; some pre-preserved, as necessary. Sample bottles were properly sealed and labeled, then placed in coolers containing blue ice and transported to the laboratory using standard chain-of-custody procedures. Chain-of-custody forms are included in Appendix E.

12.4 Laboratory Analytical Data

Samples were collected from all eight monitoring wells. Laboratory reports and chain of custody forms are included in Appendix E.

12.4.1 Semi-annual Constituents

Total dissolved solids (TDS) and total coliforms were the only semi-annual constituents detected at concentrations that exceeded established and/or recommended groundwater limitations, as follows:

Electrical Conductivity GH-MW1 (978 μS/cm)

Total Dissolved Solids GH-MW1 (788 mg/L)

Total Coliforms GH-Background (17 MPN/100 mL); SF-MW2 (14 MPN/100 mL SF-MW3 (4.0 MPN/100 mL)

Groundwater limitations were not exceeded in samples from wells GH-MW2, GH-MW4, SF- Background, and SF-MW1. Current and historic analytical results are summarized in Table 5.

13.0 GROUNDWATER MONITORING TRENDS

The results of the 2022 semi-annual groundwater monitoring event and observed trends in water quality parameters detected in the monitoring wells are discussed in the following sections.

13.1 Groundwater Depths and Elevations, Gradient and Gradient Direction

Variances in depth to groundwater (feet below top of casing) between the previous and current monitoring events are as follows:

Previous (3rd Q 2021) Current (1st Q 2022) Change (current)

GH-Background: 32.29 ft. 27.59 ft. 4.70 ft. Shallower

GH-MW1: 144.01 ft. 143.85 ft. 0.16 ft. Shallower per GH-MW2: 131.28 ft. 119.50 ft. 4.55 ft. Shallower

GH-MW4: 41.07 ft. 36.18 ft. 4.89 ft. Shallower SF-Background: 72.34 ft. 70.14 ft. 2.20 ft. Shallower SF-MW1: 24.47 ft. 17.45 ft. 7.02 ft. Shallower SF-MW2: 11.71 ft. 11.18 ft. 0.53 ft. Shallower SF-MW3: 19.43 ft. 16.17 ft. 2.26 ft. Shallower

These variances are consistent with trends from past monitoring events where groundwater is typically deeper during third quarters and shallower during first quarters. This cyclic variance correlates with the “dry” and “wet” seasons.

Groundwater (potentiometric) elevations since installation of monitoring wells in 2003 were plotted for each well to evaluate seasonal trends as shown on Charts 1 to 9. The charts show groundwater elevations generally follow a seasonal and cyclic patterns. Groundwater elevations show a more stable pattern between 2013 and 2015, which is due to a prolonged period of low precipitation from 2012 to 2015. Excessive precipitation occurred in 2017, which resulted in the recurrence of groundwater in the two deepest wells GH-MW1 and GH-MW2.

Groundwater gradients and gradient directions during first quarter 2022 were consistent with historical conditions.

13.2 Analytical Trends

Each monitoring well was sampled during the 2022 semi-annual groundwater monitoring event. Analytical results for semi-annual constituents in monitoring wells are summarized in Table 5. Exceedance of a currently established groundwater limitation is highlighted in yellow the tables and exceedance of a recommended groundwater limitation is highlighted in blue.

Groundwater limitations (established and recommended) were not exceeded in samples collected from wells GH-MW2, GH-MW4, SF-Background, and SF-MW1. Three semi-annual constituents (EC, TDS, and total coliforms) exceeded established and/or recommended groundwater limitations in one or more of the remaining wells.

Constituent concentrations that exceeded their established and/or recommended groundwater limitation and concentrations that exceeded those detected in background wells were plotted to evaluate trends as shown on Charts 10 to 15.

14.0 CORRECTIVE ACTIONS

There were no deficiencies or violations of the monitoring and reporting requirements that required corrective action.

15.0 SUMMARY AND CONCLUSIONS

The results and findings of the 2022 semi-annual groundwater monitoring event are presented and summarized in the following sections, including conclusions and recommendations where applicable.

15.1 Water Supply Monitoring

The previous MRP required annual sampling of the water supply wells in the third quarters during peak recreational use of the Glory Hole Recreation Area. The new MRP No. 2014-0153- DWQ-R5273 does not require monitoring or sampling the two (2) water supply wells.

Therefore, the water supply wells will no longer be sampled.

15.2 Influent Monitoring

Lift Station #8 is sampled monthly and samples are analyzed for the required constituents (BOD, COD, and TSS). Monthly reports were submitted to the CVRWQCB.

15.3 Lagoon (Pond) Monitoring

The WWTF lagoons (ponds) were monitored weekly (field parameter sampling and pond liner condition) during the first quarter 2022. The liners were reported as intact and in good condition. Monthly reports were submitted to the CVRWQCB.

15.4 Pond Sludge

The pond liners were reported as intact and in good condition with a thin layer of processed solids present on the bottom of the ponds. Reduction of sludge in the ponds is achieved by aerobic digestion in which bacteria digests oxygenated organic matter in wastewater. The amount of solids introduced into the ponds is not significant, given the size of the ponds. The ponds dry up annually and a thin layer of processed solids are deposited each year. A two- to three-inch thick layer of solids was observed at the bottom of both ponds as shown on Appendix A, Photos 2 and 3. Reclamation is evaluating the necessity and cost to dispose of the processed solids.

15.5 Spray Fields

Wastewater disposal was accomplished by evaporation in the ponds; therefore, the spray fields were not used during the first quarter 2022. The spray fields were last used in 2008.

15.6 Groundwater Monitoring

The results and findings of the groundwater monitoring performed at the site during the first semi-annual 2022 are summarized in the following sections.

15.6.1 Up-Gradient (Background) Groundwater Quality

Groundwater in wells SF-Background and SF-MW3 is considered to be representative of background groundwater quality. It is important to note that background groundwater chemistry can change with lateral and vertical distance, especially since the wells are screened in different rock types. This may account for the difference in manganese concentrations detected in the two background wells during previous monitoring events.

15.6.2 Depth to Groundwater and Groundwater Gradient

These variances are consistent with trends from past monitoring events where groundwater is typically deeper during third quarters and shallower during first quarters. This cyclic variance correlates with the “dry” and “wet” seasons.

Depths to groundwater in the monitoring wells were deeper during third quarter 2021 in comparison to first quarter 2022. This is consistent with trends of past monitoring events where groundwater is typically shallower during first or second quarters and deeper during third quarters. Groundwater gradients and gradient directions during first quarter 2022 were consistent with historical conditions.

15.6.3 Analytical Results

No abnormalities were noted during this monitoring period. Groundwater characteristics are consistent with historical conditions.

15.7 Recommendations for No-Purge Sampling

Semi-annual and annual monitoring events have been conducted at the site using low-flow (minimal drawdown) sampling procedure. The field parameters (pH, temperature and electrical conductivity) measured during purging have been within acceptable criteria for stability (pH: 0.2 pH unit; Temperature: 1.8 degrees Fahrenheit; and EC: 50 μmhos/cm) as shown on the purging and sampling logs (Appendix D).

Based on the results of historical monitoring and sampling it is recommended that No-Purge Sampling technique be used in all future semi-annual and annual events. Depth to groundwater, pH and EC will continue to be measured as specified in MRP No. 2014-0153- DWQ-R527. To avoid potential cross contamination, the sampling equipment will be decontaminated using Alconox solution and rinsed with distilled water prior to use in each well; nitrile gloves will be worn between wells.

It is also recommend that the use of the No-Purge Sampling technique starts during the third quarter 2022 groundwater monitoring event.

FIGURES

New Melones Reservoir

Figure 1: Vicinity Map N0 10 20 miles

WWTF

Figure 2: Location Map 0 1.5 3 miles N

Approximate Pond Elevations

Upper rim 1432 feet MSL Bottom 1425 feet MSL

Approximate Reservoir Elevation 1080 feet MSL

Figure 3: Relief Map

Image courtesy of Google Earth. Imagery date: July 24, 2011 Vertical Datum of elevations shown: NGVD 1929 - SPC - CA Zone 3 Scale not shown due to oblique view

N

SF-MW3

SF-Background

Entrance Kiosk

P d N 2 Spray Fields

GH-Background

GH-MW1

New Melones Reservoir

Pond No. 1

Pond No. 2 Spray Fields

GH-MW2

GH-MW4

SF-MW1

SF-MW2

RV Sewage Drop Station

Lift Station #8

Pond No. 1

New Melones Reservoir

Primary Supply Well

Secondary Supply Well

Wastewater Pipeline

Figure 4: Site Map

Image courtesy of Google Earth. Imagery date: July 24, 2011

SF-MW1 Groundwater Monitoring Well

N

Approximate Scale: 1 inch = 500 feet

0 500 1,000 feet250

Figure 5: Monitoring Well Location Map (oblique view)

Image courtesy of Google Earth. Imagery date: April 16, 2015 Scale not shown due to oblique view

SF-MW1 Groundwater Monitoring Well

N

GH-Background

GH-MW1

Spray FieldsPond 1

GH-MW2

GH-MW4

SF-MW1

SF-MW2

SF-MW3

SF-Background

Lift Station #8

Pond 2

Wastewater Pipeline

N

Source: California Geological Survey 2010 Geologic Map of California, online http://www.quake.ca.gov/gmaps/GMC/stategeologicmap.html

Figure 6: Regional Geologic Map

SF-MW3

SF-Background

Entrance Kiosk

P d N 2 Spray Fields

A'

GH-Background

GH-MW1

New Melones Reservoir

Pond No. 1

Pond No. 2 Spray Fields

GH-MW2

GH-MW4

SF-MW1

SF-MW2

RV Sewage Drop Station

Lift Station #8

Pond No. 1

New Melones Reservoir

Primary Supply Well

Secondary Supply Well

Wastewater Pipeline

Figure 7: Transect A-A′

Image courtesy of Google Earth. Imagery date: July 24, 2011

SF-MW1 Groundwater Monitoring Well

N

Approximate Scale: 1 inch = 500 feet

0 500 1,000 feet250

Figure 8: Diagrammatic Cross Section A-A’

A A'

Reservoir El. 1080′ 7/24/2011

E le va ti on in

F ee t ( N

G V

D

9) E levation in F eet (N

G V

D 29)

WWTF

Ponds Spray Fields

Distance in Feet

500 1000 1500 2000 2500 3000 3500 4000

E le va ti on in f ee t ( N

G V

D

9) E levation in feet (N G

V D

29)

WWTF

Ponds Spray Fields

S F

-B ac kg ro un d

(p ro j.

5′ S

S E

S F

-M W

(p ro j.

5′

N N

W

G H

-B ac kg ro un d

(p ro j.

0′ N

N W

G H

-M W

(p ro j.

5′

N N

W

G H

-M W

(p ro j.

′ S

S E

Distance in Feet

200 400 600 800 1000 1200 1400 16000

Clayey Colluvium/Soil (1 to 8.5 feet thick)

Groundwater Elevation August 2012

Well Screen Interval

N 78° E

Reservoir El. 1080′ 7/24/2011

Fractured Metamorphic and Volcanic Rock (Greenstone, Slate, Rhyolite)

GH-MW2

GH-MW4

SPRAY FIELD

2 7 3 7 N . M A I N S T R E E T , S U I T E 2 0 0 , W A L N U T C R E E K , C A L I F O R N I A 9 4 5 9 7 O F F I C E T E L . # ( 9 2 5 ) 2 7 9 - 5 0 0 0 F A X # ( 9 2 5 ) 2 7 9 - 5 0 0 1 W W W . A L I S T O . C O M

N

PROJECT NO: DATE:

IMAGE COURTESY OF GOOGLE EARTH.

POTENTIOMETRIC ELEVATION CONTOUR MAP

NEW MELONES GLORY HOLE WWTF

13-053 3/30/2022

FIGURE 9 - MARCH 2022 GROUNDWATER

SF-MW1

SF-BACKGROUND

GH-BACKGROUND

WASTEWATER INFLUENT PIPELINE

SPRAY FIELD

LEGEND

Groundwater Monitoring WellSF-MW1 Groundwater Potentiometric Elevation (feet MSL, NGVD29)

Groundwater Potentiometric Gradient Direction and Gradient (ft /ft)

Groundwater Potentiometric Elevation Contour (feet MSL, NGVD29)

0.14

SF-MW2

1314.80

1376.71

1388.19

1389.27

LIFT STATION #8

1404.95

1382.41

0.14

0.05

0.

0.22

GH-MW1

1319.57

SF-MW3

1402.47

1382.41

Figure 10: Diagrammatic Figure Showing Hypothetical Migration of Wastewater from Ponds along Subsurface Fractures to a Point Up-Gradient of Ponds

Non-Impacted Groundwater

Groundwater Impacted with Wastewater (hypothetical)

SF-Background

GH-MW2

GH-MW1

SF-MW2

GH-Background

Fractures / Foliation in Rock (hypothetical directions)

WWTF

Ponds

Leaky Pond Liner (hypothetical) Releasing Wastewater into Subsurface (migration through fractures in rock)

Migration of Wastewater to a Point Up-Gradient of Ponds

Down-Gradient of Ponds Up-Gradient of Ponds

Groundwater

Note: Groundwater is likely present only in fractures, and not throughout body of rock as shown.

SDalton Typewritten Text

SDalton Typewritten Text

SDalton Typewritten Text

TABLES

Drill Hole Completion Northing Easting Ground Surface TOC Total Well Casing/Screen Casing/Screen Screen Screen Approx. Screen Screened Filter Pack Filter Pack Bentonite Cement/Grout

ID Date Elevation Elevation Depth Material Diameter Slot Size Interval Interval Geologic Unit(s) Material Interval Seal Seal

(feet MSL) (feet MSL) (feet BGS) (inches) (inches) (feet BGS) (feet MSL) (feet BGS) (feet BGS) (feet BGS) (feet BGS)

GH-Background 6/4/2003 1991789.03 552275.23 1413.74 1415.78 60 Sch. 40 PVC 2.4 o.d./2 i.d. 0.02 40-60 1374-1354 Greenstone #3 sand 38-62.5 35-38 0-35

GH-MW1 6/3/2003 1991245.65 552433.56 1461.22 1463.42 150 Sch. 40 PVC 2.4 o.d./2 i.d. 0.02 135-150 1326-1311 Slate #3 sand 133-150 130.5-133 0-130.5

GH-MW2 6/18/2003 1991466.92 552109.65 1432.00 1434.30 142 Sch. 40 PVC 2.4 o.d./2 i.d. 0.02 122-142 1310-1290 Meta-Rhyolite/Greenstone #3 sand 120.1-145 119-120.1 0-119

GH-MW4 6/5/2003 1991743.17 552063.56 1410.78 1412.89 92 Sch. 40 PVC 2.4 o.d./2 i.d. 0.02 77-92 1334-1319 Slate #3 sand 75-92 72-75 0-72

SF-Background 6/18/2003 1992152.42 552914.89 1472.00 1475.09 95.2 Sch. 40 PVC 2.4 o.d./2 i.d. 0.02 75.2-95.2 1397-1377 Meta-Rhyolite/Greenstone #3 sand 71.9-95.2 70.9-71.9 0-70.9

SF-MW1 6/5/2003 1992200.54 551894.37 1397.85 1399.86 27.5 Sch. 40 PVC 2.4 o.d./2 i.d. 0.02 12.5-27.5 1385-1370 Slate #3 sand 10.5-27.5 7.5-10.5 0-7.5

SF-MW2 6/5/2003 1991985.83 552211.76 1398.16 1400.45 38 Sch. 40 PVC 2.4 o.d./2 i.d. 0.02 23-38 1375-1360 Greenstone and Slate #3 sand 21-38 18-21 0-18

SF-MW3 6/5/2003 1991724.35 552906.91 1416.90 1418.64 47.5 Sch. 40 PVC 2.4 o.d./2 i.d. 0.02 32.5-47.5 1384-1369 Slate #3 sand 30.5-47.5 27.5-30.5 0-27.5

MSL: mean sea level

BGS: below ground surface

TOC: top of casing o.d.: outside diameter i.d.: inside diameter

Vertical Datum: NGVD 1929 - SPC - CA Zone 3

Horizontal Datum: NAD 1927 - SPC - CA Zone 3

Wells GH-MW2 and SF-Background were installed by BOR's Mid-Pacific Regional Drill Crew. All other wells were installed by Hunt Drilling Co., Inc.

Wastewater Treatment Ponds (Lagoons)

Spray Fields

TABLE 1 - GROUNDWATER MONITORING WELL CONTRUCTION DETAILS

GLORY HOLE RECREATION AREA WASTEWATER TREATMENT FACILITY

Table 2 - Groundwater Monitoring Requirements (MRP No. 2014-0153-DWQ-R5273) Glory Hole Recreation Area WWTF

Constituent

Units

Sample Type

Sampling/Reporting Frequency b,c

Groundwater Elevationa 0.01 Feet Calculated Semiannually

Depth to Groundwater 0.01 Feet Measurement Semiannually

Gradient Feet/Feet Calculated Semiannually

Gradient Direction degrees Calculated Semiannually pH Std. Units Grab Semiannually

Electrical Conductivity µmhos/cm Grab Semiannually Total Dissolved Solids mg/L Grab Semiannually Nitrate as Nitrogen mg/L Grab Semiannually

Total Kjeldahl Nitrogen mg/L Grab Semiannually

Total Nitrogen mg/L Grab Semiannually

Sodium mg/L Grab Semiannually

Chloride mg/L Grab Semiannually

Total Coliform Organisms MPN/100mL Grab Semiannually

Zincb mg/L Grab Semiannually

Phenolb mg/L Grab Semiannually

Formaldehydeb mg/L Grab Semiannually a Groundwater elevation shall be based on depth to water using a surveyed measuring point elevation on the well and a surveyed reference elevation.

b Monitoring of the constituents zinc, phenol, and formaldehyde are required only when recreational vehicles were allowed to discharge to the wastewater system in the previous 12 months.

c Analysis of data by a California licensed professional is required at least annually.

µmhos/cm = micromhos per centimeter

Std. Units = standard pH units mg/L = milligrams per liter

MPN/100 mL = most probable number of total coliform organisms per 100 milliliters

Degrees = compass bearing

June 2002 WDR Recommendation pH

6.5 to 8.5

(USEPA Secondary MCL) same as currently established

Temperature not established no recommendation

Electrical Conductivity (EC) not established 900 umhos/cm

(CA Dept of Public Health Secondary MCL)

Total Dissolved Solids (TDS) 450 mg/L

(Agricultural Water Quality Goal) same as currently established

Nitrate as N not established 10 mg/L

(USEPA Primary MCL)

Total Kjeldah Nitrogen (TKN) not established 10 mg/L

(USEPA Primary MCL)

Coliforms

Total <2.2 MPN/100 mL

(unknown source) maximum concentration in SF-Background or SF-MW3, whichever is higher

(background groundwater quality)

1 Fecal Coliform not established maximum concentration in SF-Background or SF-MW3, whichever is higher

(background groundwater quality)

1 E.Coli Coliform not established maximum concentration in SF-Background or SF-MW3, whichever is higher

(background groundwater quality)

Formaldehyde not established 1000 ug/L

(USEPA Drinking Water Health Advisory)

Total Phenols not established 2000 ug/L

(USEPA Drinking Water Health Advisory)

Chloride 106 mg/L

(Agricultural Water Quality Goal) same as currently established

Sodium not established maximum concentration in SF-Background or SF-MW3, whichever is higher

(background groundwater quality)

Zinc not established 5 mg/L

(CA Dept of Public Health Secondary MCL)

MCL: Maximum Contaminant Level for drinking water mg/L: milligrams per liter (parts per million)

Primary MCL: Based on health, technologic, and economic criteria ug/L: micrograms per liter (parts per billion)

Secondary MCL: Based on asthetic or human welfare criteria (e.g. taste, odor, laundry staining) MPN: Most probable number 1 Fecal and E.Coli coliforms were analyzed on a voluntary basis

Semiannual Constituents

Groundwater Limitations

TABLE 3. CURRENTLY ESTABLISHED AND RECOMMENDED GROUNDWATER LIMITATIONS

GLORY HOLE RECREATION AREA WWTF

Required Monitoring Constituents

(MRP No. 2014-0153-DWQ-R5273)

Field Parameters

Observation Ground Surface Top of Casing Bottom of Well Date Depth to Depth to Depth to Groundwater

Well Elevation Elevation Elevation Groundwater Groundwater Groundwater Elevation

(feet MSL) (feet MSL) (feet MSL) (feet below TOC) (feet below ground) (feet below bottom of ponds) (feet MSL)

7/16/2003 28.29 26.25 37.51 1387.5

11/24/2003 31.85 29.81 41.07 1383.9

3/10/2004 22.11 20.07 31.33 1393.7

6/8/2004 27.17 25.13 36.39 1388.6

9/13/2004 30.41 28.37 39.63 1385.4

1/10/2005 15.87 13.83 25.09 1399.9

3/29/2005 17.07 15.03 26.29 1398.7

6/20/2005 23.41…