An Overview of the Hydrology of Adams County, PA

Transcription

1 An Overview of the Hydrology of Adams County, PA G. Patrick Bowling, P.G. Source Water Protection Coordinator PA DEP Bureau of Safe Drinking Water Division of Permits Source Protection & Allocations Section Adams County State of the Waters Conference May 17, 2017

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3 Primary Porosity Secondary Porosity (voids formed after rock was formed)

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5 Losing Stream Gaining Stream (from Fetter, 1988)

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7 Ungrouted wells are very susceptible to contamination from surface water USGS study: 70% of 146 wells sampled in PA & MD had total coliform bacteria; 25% had fecal coliforms. Most wells were ungrouted.

8 Average Annual Hydrologic Budgets for Franklin and Adams Counties, PA (from Royer and Taylor, 1980 & Becher and Taylor, 1982)

9 T ( o F) ppt (in) Effect of ET on GW Recharge in Growing Season (after Taylor and Royer, 1981) WL (ft) Time

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11 Stream Miles - Attaining: 1,220 mi - Impaired: 819 mi - Largest Source/Cause Source Unknown/Pathogens: 418 mi (from Amy Williams, DEP Bureau of Clean Water, 2017)

12 Geologic Map of Adams, Cumberland & Franklin Counties, PA (from Pa Geol. Survey Map 7, 2007) N diabase red shale/ss ss/shale limestone qtz/phyll ls/slate/schist ~ 10 mi mv

13 Red Hill Road, Oxford Twp.

14 Sinkhole near Hershey (from Bill Kochanov, PaGS)

15 (from Ogiela and Moore, 1991)

16 (from Dennis Low, USGS)

17 Adams Co. Hydrogeologic Units South Mountain - Low-grade metasedimentary/metavolcanic rocks; unconfined conditions; median well yields 7-18 gpm; recharge ~ 9-13 in/yr Gettysburg Lowland - Shale, sandstone, siltstone, diabase; unconfined to confined; yields up to several hundred gpm possible (Gettysburg Formation > New Oxford Formation >>> Diabase); recharge ~ 6 in/yr Piedmont Lowland - mostly carbonate rocks; some karstification; unconfined to semi-confined; yields 8-30 gpm (fewer wells); recharge ~6-12 in/yr Piedmont Upland - Metamorphic and sedimentary rocks; unconfined; yields <10 gpm (crystalline rocks not very productive); recharge ~8-11 in/yr

18 Potentially Stressed & Water Challenged Areas in Adams County GREEN Water Stressed Areas ORANGE Critical Water Planning Area (Marsh & Rock Creeks) BLUE Water Challenged Areas (from ICPRB, 2010; modified from SRBC GW Mgt. Plan, 2005)

19 NO 3 in Ground Water Lower Susquehanna West Basin (Low & Chichester, 2006)

20 NO 3 in Ground Water Potomac Basin (Low & Chichester, 2006; USGS DS-150)

21 Some PA & Adams Co. Drinking Water Statistics >10,000 Public Water System (PWS) wells in PA; ~1 million private wells (2nd out of all states!) 10,000-13,000 new private wells drilled statewide annually 36 CWS in Adams Co. serving 47,640 people, only 2 use surface water (Gettysburg, New Oxford) Approx. annual withdrawals for PWS sources in Adams Co.: SW 3.8 billion gallons; GW million gallons 1990 census: 15,655 private wells in Adams Co. (well data not collected in 2000 or 2010 census) 2015 Adams Co. population: 104,400 (ACOPD est.) Number of people w/ private water supplies in Adams Co: 56,760 Using avg. household size of ,200 households in Adams use private water supplies (approx. number of private wells in County)

22 Water Use in Adams County 2015 Average Daily Water Use = mgd * 6.7% 7.6% 3.4% 0.8% 0.5% 0.3% * SW = mgd (68%) GW = 5.02 mgd (32%) 80.6% CWS (12.53) Mining (1.19) Industrial (1.04) Livestock (0.53) Commercial/Institutional (0.13) Thermoelectric (0.07) Irrigation (0.04)

23 What is Source Water Protection? Source Water Protection (SWP): efforts to protect raw water quality of sources (wells, springs, streams, reservoirs) used by public water systems First barrier to drinking water contamination For ground-water source: a/k/a Wellhead Protection (WHP) - Cornerstone of SWP Protects public health, promotes sound land-use planning, avoids costs from contamination

24 Gettysburg Mun. Auth. Well #6 Comparing Costs & Benefits : ~$350,000 by GMA & ~$1.4M by DEP to respond to contamination of well Responding to contamination can be up to 200 times as costly as prevention (US EPA, 1996, Benefits and Costs of Prevention: Case Studies of Community Wellhead Protection.) Surface Water: For every 10% increase in forest cover, DW treatment costs decrease by 20% (TPL/AWWA, 2002)

25 Status of Local SWP Programs in Adams County 36 CWS Pop. served: 47,640 (46% of County) DEP-approved Programs Carroll Valley/YWC (2006),WHP Lake Meade MA (2008), WHP Biglerville WC (2012), WHP Arendtsville MWS (2014), WHP Program Underway Gettysburg MA, SWP (GW+SW) ~15 Other CWS => substantially implementing SWP % CWS Appr. % CWS SI % Pop. Covered Adams Co PA Totals (Goal) (41) 80 (75)

26 Watershed-Based Source Water Protection (SWP) Pennsylvania Early Warning Systems Establishment of Early Warning Spill Detection Networks on all major rivers in PA has been the basis for development of watershed-based SWP programs: DelVal EWS/Schuylkill Action Network (SAN) Lower Susquehanna SWP Partnership River Alert Information System (RAIN) Ohio Basin Potomac River Basin Drinking Water Source Protection Partnership

27 For more info on wellhead protection, source water assessment & protection or ground water protection: G. Patrick Bowling, P.G Division of Permits Source Protection & Allocations Section

28 Success in WHP is when nothing happens. Daniel Van Abs, NJDEP