Progress Report

November 06, 2012

San Angelo City Council

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

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Well Field Piping

Current Status: Construction is 100% complete

Contract close-out underway with the TWDB

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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

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Progress as of Oct. 29, 2012

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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

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Sta. 2624+00 looking west (Osburn cropfield)

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

Dig, Lay Bury

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

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Booster Pump Station & Well Field

NTP June 18, 2012 Substantial completion June 18, 2013 (365

days) Final Completion July 17, 2013 (395 Days)

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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

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Excavation for meter vault 1

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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.

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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.

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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.

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Well brush fabrication

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Brushing and cleaning of well

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Well purge

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Well 4 obstruction chunk

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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)

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

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Radium Removal System Site Visits

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Radium Removal System Site Visits

Questions?

November 6, 2012

San Angelo City Council

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.

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What are THMs?

Cl2 + Natural Organic Matter + Bromide Halogenated Organics (THMs)

Disinfectant THMs

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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

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Several Factors Impact THM Formation Source water quality

• natural organic matter (NOM)

• bromide

pH Water age Disinfectant type Disinfectant concentration

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How Can THM Formation be Controlled?

Cl2 + NOM + Bromide THMs

Alternate Disinfectants

•Chloramines

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How Can THM Formation be Controlled?

Cl2 + NOM + Bromide THMs

Alternate Disinfectants

•Chloramines

Remove/Reduce NOM Reactivity

•Reverse Osmosis•GAC•pH Control•Ozone•Chlorine Dioxide

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How Can THM Formation be Controlled?

Cl2 + NOM + Bromide THMs

Alternate Disinfectants

•Chloramines

Remove/Reduce NOM Reactivity

•Reverse Osmosis•GAC•pH Control•Ozone•Chlorine Dioxide

THM Removal/Degradati

on•Biological Filtration•Aeration•GAC

To limit DBP formation the COSA Uses chloramines for disinfection

0

10

20

30

40

50

60

70

80

90

100

Jun Aug Sep Nov Jan Feb Apr Jun Jul

TTH

M (

µg

/L)

Water Plant

Mathis Field

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High bromide source waters pose a challenge to utilities that use chloramines

Parameter O.H. Ivie Reservoir

Concho River

Hickory

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

Blending Treated Groundwater with Treated Surface Water Reduced THM Formation

0

20

40

60

80

100

120

140

160

180TT

HM

Fo

rmati

on

(µg/

L)

2 day THM formation

100% TSW 100% TGW75% TSW/25% TGW

50% TSW/50% TGW

25% TSW/75% TGW

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Current THM Formation

0

10

20

30

40

50

60

70

80

90

30 minutes 5 days

TTH

Ms

(µg/

L)

pH 7.5

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Optimizing pH Decreased THM formation

0

10

20

30

40

50

60

70

80

90

30 minutes 5 days

TTH

Ms

(µg/

L)

pH 7.5

pH 8.3

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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.

Questions?

November 6, 2012

San Angelo City Council