2. Agenda
1. Progress Update
a. Well Field Piping
b. Transmission Main
c. Booster Pump Station & Well Field
d. Treatment
2. THM Compliance Strategies: Challenges &
Solutions
3. Questions & Discussion
2

3. Well Field Piping
 CurrentStatus: Construction is 100%
complete
 Contract close-out underway with the
TWDB
3

4. Transmission Main
 NTP January 23, 2012
 Substantial completion July 16, 2013 (540
days)
 Final completion September 14, 2013 (600
days)
 Current status: Construction is approximately
45% Complete
4

5. Progress as of Oct. 29, 2012
5

6. Progress Summary
 Work progressing at both lay headings
 Over 28 miles installed
 Slightly behind overall schedule, but catching
up and getting closer to planned schedule
 Valves and appurtenance work ongoing with
dig/lay/bury
6

7. Sta. 2624+00 looking west (Osburn
cropfield)
7

8. Sta. 2624+00 looking east (note the solid
rock)
8

9. Dig, Lay Bury

10. Expect utilities along the way (gas, etc)….
10

11. Booster Pump Station & Well Field
 NTP June 18, 2012
 Substantial completion June 18, 2013 (365
days)
 Final Completion July 17, 2013 (395 Days)
11

12. Progress Summary
 On schedule
 Access road complete except for BCV areas
 Booster pumps and well pumps in fabrication
 Booster pump cans on site
 Cleaning and video of wells nearly complete
12

13. Excavation for meter vault 1
13

14. Hickory Wells 1-9 Background
 Wells drilled in the 1970s
 Potential obstructions or items identified by the
initial video survey at some wells.
 TCEQ required cleaning of the well casings at
each well along with removal of debris or
obstructions noted in the initial video survey
followed by a new video survey to confirm the
condition of the wells.
14

15. Current status
 Cleaning and video complete for wells 1, 3,
and 8. Casing in good condition.
 Cleaning work ongoing of wells 2, 5, 6, and
9.
15

16. Current status (Continued)
 Well 4 known obstruction cleared only to
encounter another obstruction (rubber plug).
In process of evaluating options to remove the
second obstruction.
 Well 7 initial cleaning complete, video
revealed a split in the casing at 65 feet depth.
Proposed repair is press or “swage” a sleeve
inside the casing.
16

17. Well brush fabrication
17

18. Brushing and cleaning of well
18

19. Well purge
19

20. Well 4 obstruction chunk
20

21. Groundwater Treatment Plant Design
 Procurement documents
• Select radium removal system supplier
• Complete
• Advertise November 2012
 Expedited Design schedule
• Bid plans and specs – March 2013
• Construction start – June 2013 (pending TCEQ &
TWDB approval and council award for bids)
21

22. Visited three radium removal
groundwater treatment facilities
 Vineland, NJ
• In service since 2006; retrofitted in 2011
 Upper Deerfield, NJ
• In service since 2009
 Aqua NJ Southern Division
• In service since 2008

23. Radium Removal System Site Visits
23

24. Radium Removal System Site Visits
24

26. THM Compliance Strategies:
Challenges and Solutions
November 6, 2012
City of San Angelo Council Meeting
P. Greg Pope Ph.D., P.E.
Carollo Engineers, Inc.

27. What are THMs?
Cl2 + Natural Organic Matter + Bromide 
Halogenated Organics (THMs)
THMs
Disinfectant
27

28. Why do we care about THMS?
 THMs (Trihalomethanes) are a family of four
chemicals (chloroform, bromodichloromethane,
dibromochloromethane, and bromoform) that are
regulated by the USEPA
 EPA maximum contaminant level = 80 µg/L
 Some people who drink water containing THMs
in excess of the MCL over many years may
experience health problems
28

29. Several Factors Impact THM
Formation
 Source water quality
• natural organic matter (NOM)
• bromide
 pH
 Water age
 Disinfectant type
 Disinfectant concentration
29

30. How Can THM Formation be
Controlled?
Cl2 + NOM + Bromide  THMs
Alternate Disinfectants
•Chloramines
30

31. How Can THM Formation be
Controlled?
Cl2 + NOM + Bromide  THMs
Alternate Disinfectants Remove/Reduce
•Chloramines NOM Reactivity
•Reverse Osmosis
•GAC
•pH Control
•Ozone
•Chlorine Dioxide
31

32. How Can THM Formation be
Controlled?
Cl2 + NOM + Bromide  THMs
Alternate Disinfectants Remove/Reduce THM
•Chloramines NOM Reactivity Removal/Degradation
•Reverse Osmosis •Biological Filtration
•GAC •Aeration
•pH Control •GAC
•Ozone
•Chlorine Dioxide
32

33. To limit DBP formation the COSA Uses
chloramines for disinfection
100
Water Plant
90
Mathis Field
80
70
60
TTHM (µg/L)
50
40
30
20
10
0
Jun Aug Sep Nov Jan Feb Apr Jun Jul

34. High bromide source waters pose a
challenge to utilities that use
chloramines
Parameter O.H. Ivie Concho Hickory
Reservoir River
Bromide (mg/L) 1.6 0.89 0.39
pH 7.9 8.1 7.5
TOC (mg/L) 4.8 7.6 0.2
TDS (mg/L) 1350 950 480
34

35. Blending Treated Groundwater with Treated
Surface Water Reduced THM Formation
180
160 2 day THM formation
140
120
TTHM Formation (µg/L)
100
80
60
40
20
0
75% TSW/ 50% TSW/ 25% TSW/ 100% TGW
100% TSW
25% TGW 50% TGW 75% TGW

36. Current THM Formation
90
80
70
60
TTHMs (µg/L)
50
40 pH 7.5
30
20
10
0
30 minutes 5 days
36

37. Optimizing pH Decreased THM formation
90
80
70
60
TTHMs (µg/L)
50
pH 7.5
40
pH 8.3
30
20
10
0
30 minutes 5 days
37

38. Summary
 Strategies aimed at optimizing chloramine
formation conditions may reduce THM formation.
 Bench –studies indicated that:
• Blending the source water with a lower bromide, less
reactive groundwater decreased DBP formation.
• Disinfection at elevated pH (8.3 vs. 7.5) reduced
THM formation.
38