Stuart Smith Ground Water Science Upper Sandusky, Ohio USA Crucial contributions: Mike

1. A Study in Emergency Well Disinfection in Response to Flooding from Hurricane Floyd, North Carolina Stuart Smith Ground Water Science Upper Sandusky, Ohio USA Crucial contributions: Mike Vaught, EGIS, Chapel Hill NC

2. Impacts of H. Floyd, 1999 Hurricane Floyd flood altitude, Cape Fear River, Pender County • Thousands of homes made uninhabitable • 48 people died + 100,000s livestock • Potential fecal and pathogenic bacterial contamination of wells by immersion by flood waters • 12,000 affected wells, over 2000 showed total coliform positive (unsafe) results • Many remained positive after multiple disinfection tries • Many people fended for themselves - overwhelming  Hurricane Fran Boat landing, end of Whitestocking Rd., Near Burgaw

3. To improve response to such large-scale flooding events in the future: The U.S. Federal Emergency Management Agency (FEMA) identified the need to develop procedures and protocols for emergency well disinfection that it can recommend to state and local emergency management agencies.

4. To improve response to such large-scale flooding events in the future, develop plans and recommendations: To develop these plans and recommendations: 1. A literature review and survey of practitioners about disinfection methods and information relevant to the NC well flooding 2. A field evaluation of well disinfection methods in NC wells affected by Floyd

5. Literature Review • There is an extensive literature on well disinfection • On the balance, published advice tends to be based on the incidental experience of case histories. • Little research basis for efficacy. • Recently, Illinois and Michigan work resulted in first published systematic studies of well disinfection.

6. Literature Review Recommendations and improvements: • Sodium hypochlorite is best • Calcium hypochlorite is best • Acidification to maintain pH in range that hypochlorous acid is major ion in solution • Need for agitation and contact • Well “disinfection” requires mechanical action as well as chlorine dosage (Michigan).

7. Survey of practitioners • North Carolina Environmental Health personnel • NC, SC, Virginia well contractors • National (NGWA) Master Ground Water Contractor list • “Experts” list of people known to authors: flood-experienced contractors and researchers

8. Survey results • Most affected NC counties reported multiple treatments were needed to achieve coliform-negative results. • Still, respondents expressed confidence in procedures despite multiple failures. • Two counties reported that water well contractors assisted with disinfection while 8 counties reported that they did not.

9. Survey results • Among the contractor, expert and health personnel respondents, a wide range of method chemistry and application was reported • There also seemed to be wide differences in actual knowledge of techniques. • Experienced well contractors were aware of and used disinfection improvements (acidification, well development).

10. Application or modification Total group MGWC + Special VA NC SC NC EH Premixed 56 26 7 5 10 8 Applied in well 36 20 3 2 8 3 pH is modified 34 19 1 3 9 2 Hose circulation 49 23 9 4 6 7 Spot applied 29 17 2 3 6 1 Mechanical development 43 24 7 5 6 1 Pumping to clear debris 37 18 6 4 7 2 Contact < 6 hr 3 2 0 0 1 0 Contact 6-12 hr 11 9 1 0 1 0 Contact 12-24 hr 29 10 5 3 6 5 Contact 24+hr 32 9 7 3 8 5

11. Category 50 100 200 200-500 500-1000 >1000 Total group 15 25 12 14 12 6 Special + MGWC 4 6 7 8 4 4 VA contractors 4 6 3 1 2 0 NC contractors 0 2 0 3 3 0 SC contractors 5 6 1 0 2 1 NC EH people 2 5 1 2 1 1 Chlorine concentration use reported

12. Causes of failure • Mechanical or other well faults strongly chosen as causes by all groups, including all responding environmental health professionals. • Vulnerable well location was selected by all the groups at nearly the same rate. • “Experts” emphasized not clearing wells of debris and large-scale contamination. • Among "other" responses were rust or biofouling, fecal matter or flesh in wells, unused and other exposed wells.

13. Survey results: Many comments • Emphasizing contact requirement – mixing and distribution as well as time • Specific situations require specific procedures • Many comments on inadequate well standards and oversight (NC and nationally). • Getting pumps moving – a priority

14. Survey results: Many comments • Two inch and bored wells – our types of interest – NOT viewed with much optimism • “Most 2-in wells are impossible to disinfect without removing the drop pipe assy.” (MGWC) • “Problems recur in a short time” – Dug and bored wells • “Our state (NC) needs mandatory well regulations” (public health respondent)

15. Survey results: Many comments • “If we cannot for whatever reason mechanically develop until chlorine demand is met, the outcome is not favorable.” • Problem: “Adding too much chlorine – we’ve been adding too much for years.” • Needed: “Contractor expertise and elbow grease.” • “Some state regs preclude proper disinfection…” • Comments about lack of knowledge of state regs, proper chemistry, and methodology

16. Field Evaluation: • Sampling candidate wells, and testing treatment methods on selected candidate wells was undertaken in spring and summer 2002. • A sampling of representative wells: mostly shallow bored wells and shallow-to-deep 2-inch drilled wells for area information and to identify candidates for disinfection testing. • A subset of wells selected for disinfection testing: Bored and 2-in. wells in a cluster in Edgecombe County and a cluster of 2-in. wells in Pender County.

17. Location choices • Burgaw area, Pender County: ID’d as having a selection of flood-affected wells • Edgecombe County: Clusters of mixed types of wells near Tarboro and Princeville • Mixed socio-economically, known problems • Clusters permit practical testing and treatment

18. Bored wells

19. Typically finished with concrete cap and well seal in a well house Well “Bogey D”

20. 2-in. jet pump well

21. Rare 4-in. diameter well with submersible pump

22. New “birdhouse well” modifications post-Floyd, Cape Fear River basin

23. Well sampling phase

24. Contacting well owners Croomesbridge Road, Burgaw

25. Looked at wells and sampled Croomesbridge Rd., Burgaw, Pender County

27. Buy-back property wells open almost 3 years

28. Sampling and analysis methods objectives • Identifying parameters present that may affect chlorination efficacy • Testing means of distinguishing well sources by quality differences • Microbial ecology and HPC – impacts on chlorination and coliform occurrence • TC, N-N – efficacy of disinfection

29. Sampling and analysis • Onsite pH, conductivity, ORP (redox potential), temperature • Onsite Fe (total and ferrous) • Onsite (approximate) hardness and alkalinity • Samples for BART microbial analysis • Samples for lab TC, HPC, N-N

30. Sampling and analysis methods choice objectives • Onsite pH, conductivity, ORP (redox potential), temperature: More realistic • Onsite Fe (total and ferrous) and other chemical sampling: Immediate information, a model for rapid response reconnaissance surveys, low cost per analysis – many analyses (reproducible) for same money • BART microbial analysis: Microbial ecology • Samples for lab TC, HPC, N-N – health, safety and bacterial loading

31. Hanna multi-parameter instrument for ORP, uS/cm, pH, temperature Flow meter Hach DR870 colorimeter (Fe, Mn, Cl, etc.) Out of picture: weed whacker, generator

32. Mike’s compact set up

33. Wells pumped until apparent stability of pH, conductivity, and temperature, ORP in a stable range. Values recorded at intervals. At stability, Fe, etc., total coliform, N-N and other samples collected.

34. Sampling taps were not ideal, but tap influences minimized

35. 2-in. deep well jet set up (well Bogey C) showing jet pump, suction and return flow (jet) line, purge line with totalizing meter (all flow was metered).

36. sampling Purge line Data collection Suction line Shallow well jet pump sampling assembly for wells without pumps

37. This IS organized in its own way

38. Sampling phase results • Baseline data collected for potential treatment sites – basis of comparison • Established that shallow sand water can be distinguished from deeper Castle-Hayne water • Identification of potential wells for treatment testing • All information supplied to well owners with advice as needed (“fix the UV system”)

39. Sampling phase results • Shallow sand wells in Edgecombe County study area were still pumping impaired water – probably contaminated at an aquifer scale. Deeper Edgecombe and Pender County wells were not typically pumping impaired water. • Deeper Castle-Hayne water was higher in TDS, cooler, lower ORP, similar (very low) Fe • Identification of potential wells for treatment testing: “FEMA” wells nearby tested home wells

40. Surprise benefit: Hearing the experiences of people with an unprecedented disaster

41. Sand Hill A.M.E. Church, Pender Co. – Cape Fear R. immersed to the roof line (well in sign foreground) - now restored

42. Disinfection treatment testing phase – Edgecombe locations Well Diameter (in) Depth (ft) SWL (ft BTC) Yield (gpm) Bogey A 24 24.7 10.3 7.57 Bogey C 2 75 2.86 Bogey D 24 - 18 28 7.7 6.96

43. Bogey D to west on this property Bogey A – near sampled wells and Bogey C

44. Bogey C, near sampled wells and Bogey A

45. Pender County locations • Ballard 1: Shallow (depth?) 2-in. jet-pumped well • Ballard 2: Shallow galvanized 2" with 1 1/4 suction pipe with foot valve that failed and a 3/4" pvc stuck down inside the 1 1/4 pipe. This is a standard cheap way to continue using this type well when the original 1 1/4 foot valve fails without pulling it. • Elsie Davis place: Deeper 2-in. PVC well

46. Pender well treatment testing (Ballard 1)

47. Disinfection Methodology • Following literature and recommendations, provision to 1) mix at the surface, 2) acidify to favor HOCl, and 3) distribute in well • Both Ca and Na hypochlorite tested in bored wells and Na hypochlorite in 2-in. wells • As much as possible, “off-the-shelf” materials and equipment used

48. Brushing and recirculation used in bored wells

49. Air-powered displacement initially tried on 2-in Bogey C – Chlorinated water went out screen at top – did not reach bottom

50. Na hypochlorite must be tremied to bottom and surged back