buzzi hercules hydrogeology

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  • 1. GEOLOGIC AND HYDROGEOLOGIC CONDITIONS AT AND IN THE REGION SURROUNDINGTHE HERCULES LIMESTONE QUARRY,STOCKERTOWN, PENNSYLVANIA Assessment of the Potential Impacts ofQuarry Dewatering onLocal Groundwater and Surface Water Resources with an Emphasis on Proposed Deepening of the East Pitto 50 ft msl

2. Pumping from quarry was ~ 54Million Gallons per day or ~ 84 cfs WQIZStream losses were determined to be~30 million gallons per day or ~ 46 cfs A recirculation cell was hypothesized 3. The U.S.G.S. speculated thatthere could be a HypothesizedFracture Zone with LargeHydraulic Conductivity. Risser, 2006 4. MW-1 MW-4PADEP-06MW-2West quarryMW-8inflow zone PADEP-03PADEP-04 MW-6RMW-3 PADEP-05 PADEP-01 PADEP-02 5. Grout CurtainWQIZNazareth In an attempt to eliminate the hypothetical recirculation, a grout curtain was installed in 2008.ESSROCQuarry 6. Data generated during and since the installation ofthe grout curtain provided for an expandedunderstanding of hydrogeologic conditions 7. The previous conceptualization wasof a single, unconfined aquifer asthe source of the quarry inflow. Theboundaries were assigned based ona combination of the observedlimits of stream flow losses in theBushkill and Schoeneck Creeks andwater balance, assuming a uniform,standard recharge rate. 8. Data from the post-grouting period supports aconclusion that there are two distinct groundwatersystems: a shallow unconfined system which occursin the epikarst zone and a deep confined system.The currently proposed quarry deepening would occur wholly within the unconfined aquifer zone. . 9. Buzzi Cement StockertownPlant WQIZThe grout curtain failed toNazaretheliminate WQIZ inflows, butachieved a maximum reduction ofTatamyflow of approximately 10%Various investigators hypothesizedthat the conduit flow bypassed thecurtain in the subsurface byESSROCQuarryflowing around the ends. 10. The questions which had to be answered were:Does extraction from the WQIZ derive water from theBushkill Corridor?Is there a conduit of large conductivity?Are the two groundwater zones distinct hydraulically?Will extending the depth to 50 ft msl adversely impactlocal or regional water resources? 11. The answers to those questions required a re-assessment of both the geology andhydrogeology of the quarry and the surrounding area. 12. Beginning of influentExplanation stream conditionsGeology Prominent KarstFeature Ojb OjbSurfaceExpression ofKarst trendFold West quarryaxis inflow zoneFaultTraceFault InferredLocationBushkillObObCreekObGeologicContactOutcrop ofJacksonburg Fm Ob BeekmantownGroupOjb GroundwaterFlowD U 13. Beginning of influentExplanation stream conditionsGeology Prominent KarstFeature Ojb OjbSurfaceExpression ofKarst trendFold West quarryaxis inflow zoneFaultTraceFault InferredLocationBushkill Ob ObCreekObGeologicContact .Outcrop ofJacksonburg Fm Ob BeekmantownGroupOjbThere is a pervasive SW-to-NE trend of allGroundwaterFlow structural featuresD U 14. Geology Karst solution features follow the same general SW-NE trend and also plunge toward the NE. 15. Beginning of influentExplanation stream conditionsGeology Prominent KarstFeature Ojb OjbSurfaceExpression ofKarst trendFold West quarryaxis inflow zoneFaultTraceFault InferredLocationBushkillObObCreekObGeologicContactThe hypothetical conduit of RisserOutcrop ofJacksonburg Fm would be off trend and would, of Beekmantown Ob necessity, have to plunge SW.GroupOjb GroundwaterFlowD U 16. Beginning of influentExplanationstream conditionsGeologyProminent Karst Feature OjbOjb Surface Expression of Karst trend Fold West quarry axis inflow zone Fault Trace Fault Inferred Location Bushkill ObObCreekOb Geologic ContactIn fact, both the trend andOutcrop ofplunge of the hypothetical feature Jacksonburg FmOb Beekmantownare not plausible: the trend GroupOjb would be inconsistent with the Groundwater Flowentire tectonic setting and theD Uplunge, if present, would have tobe eastward. 17. Hydrogeology 18. The quarry is in the outcrop area of theJacksonburg Formation near thecontacts with the Martinsburg Fm (upsection) and Epler Fm (down section).Within the outcrop area of the peliticMartinsburg Formation the stream iseffluent.The reach of stream over the paleokarstJacksonburg Formation is perchedabove an aquifer which is in theepikarst zone.The reach of stream from the contact ofthe Epler Formation with theJacksonburg Formation is a classic,influent karst stream characterized byfew tributaries, surface drains,predominant subsurface drainage,closed depressions, sinking streams, in-stream ponors 19. HydrogeologyIndications of TwoGroundwater Systems It was necessary to pressure grout the curtain which could only be accomplished by reducing aquifer pressures through a series of relief wells. 20. HydrogeologyIndications of TwoGroundwater Systems When the pressure relief wells were opened to provide for grout injection, there was an immediate response in wells MW-3 and MW-6. 21. HydrogeologyIndications of TwoThere is an upwelling zone inGroundwater the standing water of theWQIZ; SystemsWater jets out of seams/cracksin the standpipes of cappedwells in the WQIZ with 15-fthigh standpipes;Water rose to a height 48 ftabove the quarry floor duringgroutingGrout and rock fragments wereejected from pressure reliefwells 22. Indications of Two Unconfined zone wells did MW-1not respond to the operation Groundwaterof pressure relief wellsSystems PADEP-06 MW-4MW-2West quarryMW-8inflow zone PADEP-03PADEP-04 MW-6RMW-3 PADEP-05 PADEP-01 PADEP-02 23. Indications of Two Hydrogeology MW-1 GroundwaterSystemsPADEP-06MW-4MW-2West quarryMW-8inflow zonePADEP-03 PADEP-04 MW-6RUnconfined zone wellsresponded to precipitationMW-3and stream flow.PADEP-05PADEP-01 PADEP-02 24. Indications of Two HydrogeologyGroundwater Systems Temperatures of unconfined zone groundwater followed stream water temperatures through the fall-winter months. Confined zone groundwater remained nearly constant. 25. Indications of TwoHydrogeologyGroundwater Systems Unconfined groundwater has remained unaffected over a period of time during which the volume of quarry extraction increased. 26. Indications of Two HydrogeologyGroundwater Systems Buzzi does not pump groundwater. The water in the WQIZ flows freely upward into the stilling basins and it is pumped from those ponds to the Bushkill 27. Indications of TwoHydrogeologyGroundwater Systems In other words, there is no active hydraulic influence pulling water against the prevailing hydraulic gradient. 28. Indications of Two HydrogeologyGroundwater Systems After 19 years of artesian flow into the WQIZ under significant hydraulic pressure, there has been no adverse effect on aquifer performance. 29. Indications of TwoHydrogeologyGroundwater Systems The flows into the WQIZ do not exert a hydraulic influence on either unconfined groundwater or the Bushkill Creek. 30. HydrogeologyAbsence of responses in unconfinedgroundwater to confined zone stresses especially in interposed wells 31. Beginning of influentExplanation Hydrogeology stream conditions Prominent Karst Feature OjbOjb Surface Expression of Karst trend Fold West quarry axis inflow zone Fault Trace Fault Inferred Location Bushkill ObObCreekOb Geologic Contact Outcrop of Jacksonburg Fm The geology imparts a significantOb Beekmantown directional anisotropy to the GroupOjb groundwater system. Groundwater FlowD U 32. HydrogeologyMW-1East Sump(drained) PADEP-06MW-2 V Sump MW-4 South SumpWest quarry MW-8inflow zonePADEP-03 PADEP-04MW-6RMW-3PADEP-05PADEP-01PADEP-02 33. Quarry DeepeningCurrently approved for deepening to 0 ft mslfrom current floor at 100 ft msl. October 3,2011 report addressed Special Condition 22for hydrogeology and highwall integrity.Concern regarding hydrology is that furtherdeepening could have impact on localhydrogeology.Conducted a hydraulic test in June 2011using south sump. 34. Quarry Deepening West Quarry Inflow ZoneProposed mine deepening area 35. MW-1Quarry DeepeningSumpMW-4MW-2 MW-8 Quarry Deepening MW-3 MW-6R The sump was dewatered at a rate of 1,800 gpm in July, 2011 local effects were monitored in perimeter wells. 36. MW-1Quarry DeepeningSumpMW-4MW-2 MW-8 Quarry Deepening MW-3 MW-6R The drawdown of unconfined water within the sump was ~ 12 ft. The volume of water extracted was approximately 4 X 106 ft3 (30 million gallons). At a porosity of 4% (high) and an aquifer thickness of 100 ft, that is equivalent to the storage over an area of ~ 24 acres. 37. MW-1 Quarry DeepeningSumpMW-4MW-2 MW-8 MW-3Quarry Deepening MW-6RSump rebound was at a rate of 0.15 ft hr-1.Total rebound was 11.5 ft over a 7-dayrecovery period.The calculated Darcian hydraulicconductivity is 2 ft day-1 to 4 ft day-1. 38. MW-1 Quarry Deepening SumpMW-4MW-2MW-8Quarry DeepeningMW-6RThere were NO responses in any well to MW-3either the dewatering at 1,800 gpm orto the post-extraction recoveryExcept MW-3 which is along-strike ofthe sump. 39. MW-1 Quarry Deepening SumpMW-4MW-2MW-8MW-6R MW-3 40. MW-1 Quarry DeepeningMW-4MW-2MW-8 MW-3The structural geology imparts areMW-6R pronounced, along-strike directional anisotropy along a generally SW-NW direction.. 41. MW-1 Quarry Deepening MW-4MW-2MW-8 The structural geology imparts a cross-MW-6R strike barrier to flow and even to MW-3 hydraulic communication. .. 42. Cross-StrikeCross-Strike 43. The directional anisotropy isalso the condition within theconfined aquifer 44. MW-1Quarry DeepeningMW-4MW-2MW-8 MW-3 As a result of the directionalMW-6R anisotropy, drawdown of theunconfined aquifer to accommodatemining to 50 ft msl will be in an along-strike direction and will be bound bythe north and south boundary faults..The Bushkill in the along-strikedirection is a perched streamunconnected to groundwater and isalready lined 45. MW-1Quarry Deepening MW-4MW-2MW-8 MW-3MW-6R With a footprint area of ~ 50 acres and adepth of 50