4 Chain of Lakes and Quarry Operations Impacts

Transcription

1 Zone 7 Water gency 4.1 Program Description and Quarry Operations Impacts The Chain of Lakes/Mining rea Monitoring Program includes water level measurements and water quality analysis for many of the mining area ponds or quarry lakes within the Livermore Valley. The program also tracks and documents current mining activities, locations of discharge lines, circulation and conveyance of water between pits, and the locations of flow barriers created by clay-lined or backfilled pits. These data factor into both groundwater budget analyses and groundwater quality tracking/management. Pond Prefix* K R C P Figure 4-: Mining Pond Operators and Owners Previous Owner(s) Pond Number Current Owner Current Operator Other Name K1-8,19,32,33 Various backfilled/developed K9-14,24 SteelWave backfilled Kaiser Sand & Gravel; Hanson ggregates Rhodes & Jamieson Cal Rock Pacific Coast ggregates; RMC/Lonestar * Prefix for pond names (e.g., K37) PGC Pleasanton Gravel Company EBRPD East Bay Regional Parks District Shadow Cliffs Lake K15 EBRPD EBRPD K18 EBRPD EBRPD Lake Boris K28 PGC Hanson ggregates Lake H K3 Zone 7 Zone 7 Cope Lake K37 Zone 7 Zone 7 Lake I R3-4, 12 Vulcan Vulcan R5 PGC Vulcan Lake G R8,1,11,13,14,21,23,24, 24, 27 PGC Vulcan R22 PGC Vulcan Lake F R25 PGC Vulcan Lake E C1,2, PGC Vulcan Lake C C3,4 PGC Vulcan C5 CEMEX CEMEX C7-1, R28 PGC Vulcan Lake D P1-11,13,21,27,34,4,43-45 CEMEX CEMEX P12 EBRP EBRPD Island Pond P28, 41 CEMEX CEMEX Lake P39,42 CEMEX CEMEX Lake B Figure 4-, above, identifies the previous owners, current owner, and current mining operators associated with each lake/pond prefix and pond number as shown on Figure 4-1. nnual Report for the Groundwater Management Program 215 WY June 21

2 Zone 7 Water gency Water surface elevations are measured semi-annually in the ponds. The semi-annual pond level measurements are collected at approximately the same time as the semi-annual groundwater monitoring well level measurements. Water quality is determined annually through sampling and analysis. Zone 7 s laboratory performs a general mineral and metals analysis that is consistent with the analyses performed for the groundwater monitoring program. ll water generated during mining that is discharged to a non-quarry property (i.e. to an arroyo, Shadow Cliffs, Cope Lake) is metered. The volume of water that leaves the Valley through discharges to the arroyos is computed by prorating the flows after accounting for any repercolation back into the groundwater basin. This program also includes the tracking of pond evaporative areas, total monthly evaporative losses for the ponds, and an estimate of groundwater lost due to the export of moist gravels. Mining area evaporation accounts for a large portion of the Demand component for the annual hydrologic inventory (HI) calculation, second only to Municipal Pumping. 4.2 Results for the 215 WY Mining activities continued for Vulcan Materials (formerly Calmat) and CEMEX (formerly RMC Lonestar). Vulcan Materials continued their mining in R24 (future Lake E). CEMEX continued mining in P42 (Lake B) and started preparations to move their processing plant location so that they can start mining the area east of Shadow Cliffs (future Lake J which is not part of the Chain of Lakes). summary of mining pit conditions including their areal extent and water elevations are shown on Figure 4-1. Vulcan Materials did not discharge into the rroyo Mocho in the 215 WY. The 215 WY was the first complete water year that Vulcan did not discharge into the rroyo Mocho; all water was captured in Cope Lake instead. Vulcan diverted 4,89 F of water into Cope Lake in the 215 WY. n estimated 2,999 F was transferred from Cope Lake to Lake I via the conduit during the 215 WY. lthough this extracted groundwater is not leaving the basin the impact of quarrying in R24 (future Lake E) caused a localized depression in the mador East Subbasin (Figure 4-1). The groundwater extracted from R24 is coming from the same portion of the aquifer as the westernmost CWS supply wells. CEMEX did not discharge into the rroyo Valle during the 215 WY. The groundwater pumped from their active excavation (P42) was transferred to onsite ponds and used as a gravel wash water source. Consequently, some of this water evaporated or left the Valley as gravel moisture, and some percolated through the ponds bottoms and sides and back into the aquifer. nnual Report for the Groundwater Management Program 215 WY 4-2 June 21

3 Zone 7 Water gency In total, an estimated 3,143 F of water evaporated from all the mining area ponds and 7 F left as gravel moisture during the 215 WY, from CEMEX and Vulcan operations. Zone 7 continued its cooperative off-site recharge program with EBRPD using the Shadow Cliffs lake as a spreading pond. EBRPD diverted 1,17 F from the rroyo Valle into Shadow Cliffs compared to the average of 9 F per year. The additional water was used to raise Shadow Cliff s water level back to the pre-drought condition (approximately 33 feet elevation), and then maintained at that level for the remainder of the 215 WY. Water elevations were measured in most of the pits in the mining area that contained water (i.e., the lakes or ponds) during the 215 WY and the results are shown on Figure 4-2. The water elevations from the pits that are in direct communication with the upper aquifer are included in the Groundwater Monitoring Program s dataset used for the upper aquifer groundwater elevation contour maps (Section 5; Figure 5-8 and Figure 5-9). This includes water elevations from M- R24, which is actively being mined and is now believed to be in contact with the upper aquifer. Ponds M-R22, M-R23, and M-R3 are no longer considered to be connected to the upper aquifer based on lack of correlation between pond water levels and upper-aquifer groundwater elevations. Water quality was also monitored in certain mining ponds (Figure 4-3). Salt concentrations, measured as TDS, in the mining area ponds ranged from about 377 mg/l in future Lake G (pond R8) to over 1, mg/l in pond C1 (future Lake C) in September 215. In the past, Cope Lake has contained high TDS water (over 1,4 mg/l) due to evaporation which concentrated the salts in the clay-lined pond. Now that Vulcan Material s discharge from their quarry dewatering operations is being captured in Cope Lake, the lake s TDS has lowered to under 5 mg/l. The TDS, nitrate, and boron concentrations measured in the mining area ponds that are in direct communication with the upper aquifer are included in the Groundwater Monitoring Program s dataset used to create the upper aquifer concentration maps (Section ; Figure -4 to Figure -7). 4.3 Chain of Lakes Recharge Projects This section summarizes recent activities on Zone 7 Chain of Lakes Projects that will enhance Zone 7 s ability to monitor and recharge the groundwater basin. Many of the quarry pits have been dug deep into the Upper quifer, creating windows into the groundwater basin, and exposing groundwater to large evaporative losses. Groundwater is also pumped from some of the pits and transferred to others or discharged to the arroyos to facilitate the gravel extraction in the pits being actively mined. s mitigation for removal of aquifer material and interruption of groundwater movement resulting from the mining of aggregate resources and occasional placement of less permeable material in former pits in the central portion of the groundwater basin, ownership of ten of the nnual Report for the Groundwater Management Program 215 WY 4-3 June 21

4 Zone 7 Water gency resulting quarry lakes (Lakes through I and Cope Lake) is to be transferred to the Zone 7 Water gency for water resources management purposes (Figure 4-B). Two of the lakes have already been transferred to Zone 7 (Lake I and Copee Lake) and are currently operated and maintained by Zone 7 for storage and groundwater replenishment. Figure 4-B: Map of Future Chain of Lakes Full implementation of the Chain of Lakes use by Zonee 7 is not expected before 258 when the mining operations are projected to be completed. However, Zone 7 is working on several interim projects that are designed to convey, capture, and recharge imported SWP water and captured mining releases, and/ /or detain peak stormwater flows. In 213 and 214, under an agreement with Zone 7, Vulcan Materials extended their water discharge pipeline from their existing rroyo Mocho turnout to Cope Lake and began capturing groundwater pumped during quarry operations and usedd for gravel washing operations in Cope Lake. Later in 214, Zone 7 installed a pipeline between Cope Lake and Lake I to convey nnual Report for the Groundwater Management Program 215 WY 4-4 June 21

5 Zone 7 Water gency Vulcan s discharge water to Lake I, where there is a much higher capacity for storage and aquifer recharge. s noted in Section 4.2, all of the Vulcan water generated in the 215 WY was captured in Cope Lake and over half of that was transferred to Lake I. nother future, but near-term, project involving some of the completed Chain of Lakes and aquifer recharge is the rroyo Mocho Diversion, which is anticipated to be in service within the next few years. This project consists of a fish-friendly stream diversion facility on the rroyo Mocho that will divert water (e.g., imported SWP water released to the rroyo from the SB) into Lake H and then, in turn, convey the water into Lake I to further enhance Zone 7 s artificial aquifer recharge capacity. Hanson ggregates (Hanson) is responsible for the design, permitting and construction of the diversion facility per the existing agreement between Zone 7 and Hanson (formerly Kaiser Sand and Gravel), 1987, and the Livermore-mador Valley Quarry rea Reclamation (LVQR) Specific Plan, In the 215 WY, Hanson submitted a design for the diversion structure to Zone 7 for comments. Hanson incorporated Zone 7 s comments and was ready to submit a revised permit application to the rmy Corps of Engineers in the 21 WY. Zone 7 is supporting Hanson, as appropriate, since Zone 7 will eventually own and operate the structure. In 212, CEMEX started the amendment process for their surface mining permit (SMP-23) due to anticipated changes in their planned mining. These proposed changes include realigning the rroyo Mocho, which was previously captured in Lake then exited Lake B under the original SMP-23. The amendment also proposes changes to the shape and size of Lakes and B. In the 215 WY, CEMEX came up with a conceptual design for the rroyo Valle diversion structure that was acceptable to staff. Staff has been working closely with the lameda County Community Development gency (CCD) which oversees SMP-23. n updated Environmental Impact Report (EIR) was started by Benchmark, a consultant to CCD, and will continue into the 21 WY. Staff will continue to work with CEMEX and the CCD. nnual Report for the Groundwater Management Program 215 WY 4-5 June 21

6 Zone 7 Water gency This Page Intentionally Left Blank nnual Report for the Groundwater Management Program 215 WY 4- June 21

7 8B G LkH LkI K37 R13 K4 P K5 K K18 1P LEGEND K15 22D P13 1K2 Well Number (abbreviated) Groundwater Elevation (NM = Not Measured) P12 P P11 3 P4 P42 2, 1 North Canyons Parkway Livermore, C P3 C C4 C3 C2 39 C1 P39 34 P P28 3D P P41 Sources: Esri, DeLorme, NVTEQ, TomTom, Intermap, increment P Corp., GEBCO, USGS, FO, NPS, NRCN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri Japan, METI, Esri China (Hong Kong), swisstopo, and the GIS User Community 43 Feet ZONE 7 WTER GENCY C5 25C , 19D C8B P P1 35 Mining rea Ponds J Fall 215 Contours (Interval = 1') Hatch pattern towards lower elevation Future Chain of Lakes (revised 215) C8 P4 P45 P C7 P27 P44 P34 P P P P Monitoring; piezometer % Municipal 2J Nested Pumped From 3 Static (same as groundwater) 2Q Pumped Into Variable Not Connected with Groundwater ctive Excavation Excavated Backfilled with Silt and Clay Streams Subbasin Boundary P ( Supply Mining P1 P2 215 Program Wells (Upper quifer) K C1 R28 P43 DRWN: TR/CW SCLE: 1 in = 2, ft REVIEWED: MK DTE: June 1, 21 File: E:\MONITOR\M\215WY\Fig4-1-Miningrea15.mxd 44 2C R K32 K K19 42 C9 P21 ShCliffs E R14 R11 R1 P21 K R4 K14 3 K8 R R12 K12 K11 R24 R21 44 K K1 K13 R3 18 R K3 K9 K1 R5 R E K2 2 K3 K R23 R N P R H G R22 R8 9J K K H C K37 1D G B C Figure 4-1 Map of Gravel Mining Pits with Groundwater Elevation Contours (September 215) Livermore Valley Groundwater Basin

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9 FIGURE 4-3 WTER QULITY RESULTS FOR MINING RE WTER SMPLES 215 WTER YER DTW TEMP. EC Mineral Constituents (mg/l) Select Metals (mg/l) TDS Hard SITE ID DTE (Ft) o C umhos/cm ph Ca Mg Na K HCO3 SO4 Cl NO3 SiO2 B s Fe Cr mg/l mg/l M-C1 9/24/ < <.5 < M-K15 1/1/ < <.5 < M-K18 1/1/ < <.5 < M-K28 9/24/ < <.5 < M-K3 9/24/ < <.5 < M-K37 9/24/ < <.5 < M-P1 1/1/ < <.5 < M-P12 1/1/ < <.5 < M-P28 9/24/ < <.5 < M-P41 9/24/ < <.5 < M-P42 9/24/ <.5 < M-P44 9/24/ < <.5 < M-R3 9/24/ < M-R4 9/24/ < < M-R8 9/24/ < M-R23 9/24/ < M-R24 9/24/ < E:\MONITOR\M\215WY\Fig4-3-MChem15.xls 2/25/21 Figure 4-3 Page 1 of 1