BWA WTP Existing Condition Evaluation · Technical Memorandum No. 1 BWA WTP Existing Condition Evaluation 1-4 Document Code 1.3.2 Finished Water Quality The Plant finished water consistently - [PDF Document] (2024)

APPENDIXF

BWAWTPExistingConditionEvaluation

December2013

1-1 Document Code

Technical Memorandum No. 1

BWA WTP Existing Condition Evaluation

1.1 Introduction The Brazosport Water Authority (BWA) treats and delivers water to the Cities of Angleton, Brazoria,

Clute, Freeport, Lake Jackson, Oyster Creek and Richwood, as well as two Texas Department of

Criminal Justice prisons and the Dow Chemical Company. The existing BWA Water Treatment Plant

(WTP) is located in Lake Jackson (as shown in Figure 1-1 on the following page). The BWA water

supply is provided by a 45,000 ac-ft/yr run-of-the-river rights from the Brazos River. This permit has

a priority date of 1964. BWA’s water supply is tied to Dow’s water supply by virtue of the diversions

from the Brazos River into the Harris or Brazoria Reservoir and releases from these reservoirs to the

Dow fresh water canal. Water is diverted to the Brazoria Reservoir, located at river mile 24 when

fresh water is available at this location. During periods of low flow, the salt water wedge from the Gulf

of Mexico moves up the Brazos River and fresh water diversions are moved to the Harris Reservoir

located at river mile 44. Water from the Harris Reservoir is released into Oyster Creek and then

diverted to the fresh water canal. Water from the Brazoria Reservoir is released into Buffalo Camp

Bayou and diverted to the fresh water canal. The water treatment plant diverts water from the fresh

water canal. This Plant was constructed in 1987 to serve Brazosport Water Authority customers.

As part of the Brazoria County Water Master Plan, CDM Smith completed an evaluation of the current

Plant systems in order to provide recommendations to BWA that would improve their existing WTP

and transmission system, as well as increase the capacity of the Plant and transmission system to

meet projected water demands of their existing participating customers and potential customers in

Brazoria County. As part of this evaluation, CDM Smith completed the following:

Review of water quality regulations as they relate to the Plant;

Review of the current water quality and potential impacts on the Plant;

Assessment of the existing water treatment plant;

Identification and evaluation of near-term upgrade and expansion alternatives; and,

Identification and evaluation of long-term upgrade and expansion alternatives.

1.2 Water Quality Regulations Water quality standards are established to ensure that safe and aesthetically acceptable drinking

water is supplied to the public. Drinking water standards are established by the Texas Commission on

Environmental Quality (TCEQ) to assure the safety of public water supplies. These standards,

presented in Chapter 290, Subchapter F of the Texas Administrative Code, comply with the Federal

“Safe Drinking Water Act” and the “Primary Drinking Water Regulations”, promulgated by the

Environmental Protection Agency (EPA). The complete National Primary Drinking Water Regulations

and a list of contaminants and their maximum contaminant levels may be accessed on the U.S.

Environmental Protection Agency Web site (www.epa.gov/safewater/contaminants/index.html).

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Figure 1-1 Map of Brazoria County

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The National Secondary Drinking Water Regulations are recommended standards developed by the

EPA to address constituents that may impact the aesthetic quality of drinking water.

These standards are typically included to improve consumer satisfaction. These parameters include

inorganic and physical characteristics:

Inorganic characteristics include such parameters as total dissolved solids (TDS), hardness,

iron, and manganese.

Physical characteristics include such parameters as taste and odor, color and corrosiveness.

Based on review of available data, BWA is currently in compliance with the EPA and TCEQ regulation

requirements for surface water treatment plants. Table A-1 in Appendix A summarizes the primary

drinking water regulations and presents the current compliance status for the BWA WTP.

1.3 Water Quality The source water for the Brazosport Water Authority (BWA) Water Treatment Plant (WTP) is the

Brazos River via the Harris and Brazoria Reservoir and the fresh water canal system. This section

reviews the raw, finished, and distribution system water quality.

1.3.1 Brazoria Reservoir Raw Water Quality The source water for the BWA WTP is the Brazos River via the Harris and Brazoria Reservoir and the

fresh water canal system, which was constructed in 1954. The Brazoria reservoir has a capacity of

21,000 acre-feet and a surface area of 1,865 acres at a crest elevation of approximately 31 feet above

mean sea level. Approximately 8,000 acre-feet are usable. The Harris Reservoir has a capacity of 7,000

acre-feet and a surface area of 1,663 acres at a normal maximum surface elevation of approximately

43 feet above mean sea level. Approximately 5,200 acre-feet are usable.

The most recent water quality data are shown in the following Table 1-1.

Table 1-1 Raw Water Characteristics

Year or Range Characteristic Unit Average Level Maximum Level Minimum Level

2008 2010 Turbidity NTU 49 113 24 2008 2010 Alkalinity mg/L 142 313 12 2008 2010 TOC mg/L 4.56 13.80 1.80 2008 2010 pH NU 7.85 8.17 7.05 2008 2010 Hardness mg/L 179 224 126 2008 2010 TDS mg/L 319 476 4.16 2008 2010 Arsenic mg/L 0 0.002 <0.005 2008 2010 Barium mg/L 0.16 0.34 0.10 2008 2010 Copper mg/L 0.01 0.03 0.006 2008 2010 Nickel mg/L 0 0.004 <0.005 2008 2010 Lead mg/L 0 <0.005 <0.001 2008 2010 Sulfate mg/L 48 78 33 2008 2010 Chloride mg/L 103 166 40 2008 2010 Nitrate mg/L 0.72 0.98 <0.50 2008 2010 Fluoride mg/L 0.53 0.84 0.30 2008 2010 TTHM ug/L UD UD UD 2008 2010 HAA5 ug/L <1.0 <1.0 <1.0 2008 2010 E. coli (CFU/100 mL) 115 548 2

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1.3.2 Finished Water Quality The Plant finished water consistently meets all regulatory requirements, and filtered water turbidities

are good. BWA is also currently meeting the compliance schedule required by the Long Term 2

Enhanced Surface Water Treatment Rule. The most recent data are shown in the following Tables 1-2

through 1-8.

Table 1-2 Average Residual Chlorine in Distribution System

Year or Range Disinfectant Average

Level Minimum

Level Maximum

Level Source of Chemical

2008 2012 Chloramine

(total chlorine) 2.03 1.0 5.0 Disinfectant used to control microbes.

Table 1-4 Unregulated Contaminants

Year or Range Contaminant Average

Level Minimum

Level Maximum

Level Unit of

Measure Source of Contaminant

2008 2011 Chloroform 4.4 UD 8.6 ppb Byproduct of drinking

water disinfection.

2008 2011 Bromoform 1.7 UD 2.1 ppb Byproduct of drinking water disinfection.

2008 2011 Bromodichloromethane 3.0 UD 3.5 ppb Byproduct of drinking water disinfection.

2008 2011 Dibromochloromethane 3.9 UD 4.6 ppb Byproduct of drinking water disinfection.

Table 1-5 Regulated Contaminants

Year or Range Contaminant Average

Level Minimum

Level Maximum

Level MCL MCLG

Unit of Measure

Source of Contaminant

Inorganic Contaminants

2008 2011 Arsenic - <0.001 <0.005 10 0 ppm

Erosion of natural deposits; runoff from orchards; runoff from glass and electronics production wastes.

2008 2011 Barium 0.11 0.08 0.13 2 2 ppm

Discharge of drilling wastes; discharge from metal refineries; erosion of natural deposits.

2008 2011 Fluoride 0.59 0.22 1.18 4 4 ppm

Erosion of natural deposits; water additive which promotes strong teeth; discharge from fertilizer and aluminum factories.

2008 2011 Nitrate 1.15 <0.50 1.98 10 10 ppm

Runoff from fertilizer use; leaching from septic tanks, sewage; erosion of natural deposits.

Organic Contaminants

2008 2011 Atrazine 0.78 0.29 1.90 3 3 ppb Runoff from herbicide used on row crops.

Table 1-3 Disinfection Byproducts Year or Range

Contaminant Average

Level Minimum

Level Maximum

Level MCL

Unit of Measure

Source of Contaminant

2008 2011 Total Haloacetic

Acids 9.63 <1.0 11.90 60 ug/L

Byproduct of drinking water disinfection.

2008 2011 Total

Trihalomethanes 11.98 UD 13.60 80 ug/L

Byproduct of drinking water disinfection

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Year or Range Contaminant

Average Level

Minimum Level

Maximum Level

Unit of Measure Source of Contaminant

2008 2011 Source Water 4.56 1.80 13.80 ppm Naturally present in the environment.

2008 2011 Drinking Water 3.31 1.40 11.40 ppm Naturally present in the environment.

2008 2011 TOC Removal 24.6 - - % removed NA

Table 1-6 Secondary and Other Constituents Not Regulated

Year or Range Constituent Average

Level Minimum

Level Maximum

Level Secondary

Limit Unit of

Measure Source of Constituent

2011 2011 Aluminum 0.021 - - .05 ppm Abundant naturally occurring element.

2008 2011 Bicarbonate 153 137 178 NA ppm Corrosion of carbonate rocks such as limestone.

2011 2011 Calcium 43.2 - - NA ppm Abundant naturally occurring element.

2008 2012 Chloride 111 57 160 300 ppm

Abundant naturally occurring element; used in water purification; byproduct of oil field activity.

2008 2011 Copper 0.033 0.001 0.049 1 ppm

Corrosion of household plumbing systems; erosion of natural deposits; leaching from wood preservatives.

2008 2011 Hardness as

Ca/Mg 170 123 215 NA ppm

Naturally occurring calcium and magnesium.

2011 2011 Magnesium 11.9 - - NA ppm Abundant naturally occurring element.

2008 2011 Nickel - <0.001 0.002 NA ppm Erosion of natural deposits.

2008 2012 pH 7.63 7.20 8.20 7 units Measure of corrosivity of water.

2009 2011 Sodium 78 66 94 NA ppm Erosion of natural deposits; byproduct of oil field activity.

2008 2012 Sulfate 58 27 85 300 ppm

Naturally occurring; common industrial byproduct; byproduct of oil field activity.

2008 2012 Total

Alkalinity as CaCO3

125 112 146 NA ppm Naturally occurring soluble mineral salts.

2008 2012 Total

Dissolved Solids

393 260 496 1000 ppm Total dissolved mineral constituents in water.

Table 1-7 Total Organic Carbon

Table 1-8 Turbidity

Year or Range

Contaminant Highest Single Measurement

Lowest Monthly % of Samples

Meeting Limits

Turbidity Limits

Unit of Measure

Source of Contaminant

2008 2011 Turbidity 0.47 98.9 0.3 NTU Soil runoff.

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1.4 Existing Facility Conditions and Expansion Considerations The BWA WTP was constructed in 1987 in Lake Jackson to serve to the Cities of Angleton, Brazoria,

Clute, Freeport, Lake Jackson, Oyster Creek and Richwood, as well as two Texas Department of

Criminal Justice prisons and the Dow Chemical Company. Since then, several major facility

improvements have been constructed to meet the increasing water demands brought about by

development in Brazoria County.

BWA currently holds contracts to provide water to these customers, which are presented (with their

current contract amounts), in Table 1-9.

Customer Water Contract Amount (mgd)

Angleton 1.80

Brazoria 0.30

Clute1 1.00

Freeport 2.00

Lake Jackson 2.00

Oyster Creek 0.095

Richwood 0.235

Dow 1.00

TDCJ 0.75 1 Contract amount could increase by 1.0 mgd as recently requested by the City.

The BWA WTP has a capacity of 17.8 million gallons per day (mgd). The future demands in 2025 and

2040 are 26 mgd and 32 mgd, respectively. Based on the future projected demands, future Plant

capacity will need to be increased.

CDM Smith visited the Plant on May 24, 2012, to assess the current condition of the Plant processes

and assets. In addition, an electrical and instrumentation and control site visit was conducted

November 20, 2012, to review the state of the electrical and SCADA systems currently installed at the

Plant. This section provides an overview of the capacity and condition of these existing equipment

and facilities. Additionally, recommendations for improvements at the Plant and the probable costs for

these improvements are provided.

1.4.1 Treatment Process Overview Treatment is achieved using solids contact clarification and filtration. Water is pumped into the Plant

from the Raw Water Intake by six raw water pumps. Following treatment, finished water is stored in

one of two clearwells onsite and then transferred to the transmission system by four high service

pumps. Waste solids throughout the process are sent to the site’s two sludge basins. These processes,

along with raw water pumping and conveyance and chemical injection, are discussed individually in

the following subsections.

Table 1-9 BWA WTP Customers and Contract Amounts

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1.4.2 Raw Water Intake, Pumping and Conveyance Facilities The Raw Water Intake and Pump Station

(highlighted in blue in the figure to the right) are

located east of the BWA WTP site and uptake water

from the fresh water canal using a vertical concrete

intake structure. The intake and pump station

consist of two trash screens, four fine bar screens,

and six raw water pumps and appurtenances. The

intake structure is 31-feet wide and approximately

nine-feet deep at the entrance. The raw water flows

through the trash and fine screens, and into the 17.5-

foot intake, where the water elevation is

approximately 7.1 feet above the finished floor.

The Raw Water Pump Station consists of six vertical

turbine pumps, which have a combined capacity of 27.6 mgd. Three pumps are part of the original

construction, while the other three pumps were installed by Plant personnel at a later date. Five of the

six pumps are equipped with variable frequency drives. The raw water pump parameters are

presented in Table 1-10. The raw water pumps draw water out of the canal and convey it to the WTP

through a dedicated 36-inch ductile iron pipeline into the splitter box at the beginning of the process

train. The flow to the Plant is controlled by a flow control valve.

At the pump station, BWA has the ability to add alum or polyaluminum chloride (PAC) as a coagulant

aid, copper sulfate for algae control, and cationic polymer. Granular activated carbon can be added for

taste and odor control but is not used often at the Raw Water Pump Station due to limited detention

time.

The raw water pumps are in good working condition; however, based on population projections

(which will be presented in the Facility Master Plan), additional pumps may be needed in order to

meet the 2040 max day demands.

For the 36-inch conveyance piping, with a water demand of 26 mgd, the velocity in the piping will be

at just above five feet per second (fps), which is acceptable, and could reach as high as high as 7.0 fps

with a water demand of 32 mgd. As the plant reaches these demands, additional pipeline will need to

be constructed.

The capacity of the intake and pump station controls the capacity of the entire Plant. Future Plant

expansions will increase the velocity in the intake and through the raw water pipeline. CDM Smith

Table 1-10 Raw Water Intake Pump Parameters Parameter Value

Number of Pumps 6

Pump Capacity 2,200 gpm (1) 3,400 gpm (5)

Total Capacity 27.6 mgd Firm Capacity 22.8 mgd

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recommends a physical hydraulic modeling study be conducted to determine the intake and pump

station capacity more precisely.

1.4.3 Water Treatment Plant

The treatment process consists of solids contact clarification and filtration. These processes are

discussed individually in the following subsections.

1.4.3.1 Clarification

The Plant has three clarification trains (highlighted

in blue in the figure to the right) – two constructed

in 1987 and one in 1994. The original two clarifiers

have an 82-foot diameter and a wall height of 22

feet (not including conical bottom). The third one is

100-foot in diameter and has a wall height of 22

feet, 2 inches (not including conical bottom). The

original two clarifiers have a volume of 7.6 million

gallons (MG) each, while the third clarifier has a

volume of 11.3 MG; the total volume is 26.5 MG.

Prior to the clarifiers, there is a splitter box that

receives flow from the Raw Water Pump Station

and sends it to the three clarifiers through a 24-inch

pipeline. The splitter box is experiencing a

siphoning effect that causes hydraulic surging. This in turn causes an offensive chemical gas smell.

CDM Smith recommends venting the splitter box to allow for air to continuously escape.

Chlorine dioxide is injected prior to clarification and monitored in each of the clarifiers. Polymer and

coagulant are also injected. The decant water from the sludge basins and the washwater waste from

the filters are sent back to the splitter box prior to the clarifiers by a three-inch PVC line and a six-inch

ductile iron line, respectively. It is recommended that each of these lines have flowmeters added.

The clarifiers are in need of painting but are in fair

working condition, and they have enough capacity

with all three online to meet the 2025 demands.

However, the current clarification capacity will not

meet the 2040 demands – an additional 100-foot

diameter clarifier will be needed.

1.4.3.2 Filtration

The existing filtration system at the BWA WTP

includes eight granular media filters (highlighted in

blue in the figure to the right). Six of these filters

were constructed and placed into operation in

1987, with two additional filters added in 2004.

Although the filters were installed in separate

projects, the design for each project was essentially

the same. The existing filters with one filter out of

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service have a total combined surface area of 2,496 square feet (sf) (356.5 sf/filter). The filters have a

combined firm rated capacity of 18 mgd based on a filtration rate of 5.0 gpm/sf.

Filters No. 1 through 6 were originally designed with clay tile underdrains that have since been

retrofitted with air scour systems. The newer filters, Filters No. 7 and 8, were designed with stainless

steel tepee underdrains and air scour. All filters include a dual media filtration bed consisting of 18-

inches of anthracite coal and 12-inches of sand supported atop 12-inches of gravel.

Although the existing filters were constructed in two phases, all eight filters operate in parallel. The

clarified water from each of the three clarifiers flows into the filter influent channel. This water is

evenly distributed among the on-line filters. In addition to the commonality of the filter influent

channel, the filtered water pipe header, filter waste backwash water pipe, backwash supply piping,

and air scour piping are shared.

During normal filter operation, clarified water enters a filter gullet from the filter inlet channel via an

18-inch inlet butterfly valve. The gullet wall and the washwater troughs are submerged during normal

operation with the operating water surface elevation maintained at 23.7 to 27.7 feet. Settled water

flows directly from the gullet to the filter bed and then down through the media. The filtered water

collects in the underdrain system, flows from the end of each underdrain lateral, passes through a 12-

inch outlet pipe, and into the filtered water header. The filtered water is then conveyed through a

common filtered water header pipeline to one of two clearwells.

The filters are in good working condition; however, they will need more capacity to meet future

demands. In order to meet the 2025 demands, four additional filters will need to be constructed.

Another two will need to be built to meet the 2040 demands.

1.4.3.3 Filtered Water Conveyance

At the BWA WTP, filtered water is conveyed through the effluent junction box to the clearwells for

obtaining disinfection CT credit and storage. The filters have an underdrain that collects water after it

passes through the filter media. Water flowing through these underdrains is metered using a venturi

meter located in the filter pipe gallery. The Plant is also equipped with turbidity meters to monitor

individual filter turbidity performance to comply with regulatory requirements.

Using the current 36-inch piping for the effluent junction box, with a water demand of 24 mgd in 2025,

the velocity in the piping will increase to just above five feet per second, which is acceptable, and

reach as high as 6.6 fps in 2040 with a water demand of 36.6 mgd. With the addition of new filters,

upgrades to the effluent junction box and effluent piping are recommended.

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1.4.3.4 Finished Water Storage

The BWA WTP stores finished water in two

onsite clearwells (highlighted in blue on the

figure to the right), with a combined storage

volume of 1.3 MG. The original clearwell has an

88-foot diameter and a wall height of 10 feet, 5

inches, with a capacity of 0.4 MG. The second

clearwell has a 137-foot diameter and a wall

height of 10 feet, 5 inches, with a capacity of 0.9

MG. Filtered water flows to the large baffled

clearwell and then to the high service pump

station wet well. The small clearwell floats off

the wet well.

The storage volume available in the clearwells

provides contact time and therefore plays a

significant role in the Plants’ disinfection

capability. Clearwells should be operated in compliance with approved CT study to assure proper

disinfection.

TCEQ requires a minimum finished water storage capacity to equal or exceed five percent of the rated

plant flow. At 17.8 mgd 0.89 MG of clearwell capacity is required. The TCEQ minimum does not take

into account the treatment process used at the BWA Plant. The solids contact clarifiers used do not

work well with significant changes in flow. With a small clearwell, the flows to the clarifiers are

constantly changing in response to rapid changes in clearwell levels which makes operations difficult.

It has been CDM Smith’s experience that with solids contact clarifiers, that a minimum clearwell

volume of 30 percent of plant capacity should be provided. For the 17.8 mgd plant, that results in a

clearwell capacity of 5.3 MG. In addition to efficient operation of the plant processes, the BWA WTP

serves areas that are prone to hurricanes. As a health and safety measure for the BWA customers, they

should consider providing clearwell capacity equal to the average day demand which is currently 10

mgd.

1.4.3.5 High Service Pumps

Finished water stored in the BWA WTP clearwells is supplied to the distribution system by four,

6,000-gpm VFD-controlled, high service pumps. They pump to the Brazoria Ground Storage Tank

(GST) and 14 GSTs in Clute, Richwood, Oyster Creek, Freeport (two tanks), Lake Jackson (two tanks),

Angleton (two tanks), TDCJ(two tanks), and Dow (two tanks). Pump parameters are presented in

Table 1-11.

Table 1-11 High Service Pump Parameters Parameter Value

Number of Pumps 4 Pump Capacity 6,000 gpm Total Capacity 34.6 mgd Firm Capacity 25.9 mgd

Note: The fourth pump is being installed by BWA.

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These pumps are in good operational condition. Based on water demand projections, no additional

pumps will be needed to meet the 2025 demands, with an additional pumping capacity of at least

3,500-gpm needed for the 2040 demands.

The high service pump station also houses two 8,000-gpm backwash pumps with VFDs and two 700-

gpm plant water pumps with VFDs.

1.4.3.6 Filter Backwash and Recycle System

The Plant employs dual-media gravity filters consisting of anthracite and sand, on top of support

gravel. Filters are monitored for turbidity, headloss, and run time to determine when backwashing is

required. Filters are normally backwashed based on time as opposed to turbidity or headloss.

Backwashing directs flow upwards through the filter to wash out floc that has collected on the media

and requires a significant amount of flow. The water to be used for backwashing is taken from the

clearwell and pumped directly to the filters. One 8,000-gpm vertical turbine backwash pump conveys

needed backwash water through a venturi flow meter on the backwash water pipeline that feeds into

the basin to control which filter will be backwashed. A backwash rate of up to 22 gpm/sf is available

from one of the two pumps (one duty, one standby), more than sufficient for efficient backwashing.

The waste filter backwash water is collected and

piped to the washwater water recovery basin

highlighted in blue to the right. Recycle pumps

pump the waste backwash water to the raw water

pump discharge header.

CDM Smith estimated the backwash water

requirements for each filter. Assuming a

conservative backwash rate of 20 gpm/ft2 for 20

minutes, approximately 142,000 gallons are used

for each backwash. The washwater recovery basin

has a volume of approximately 300,000 gallons or

approximately the volume of two backwashes. The

Plant has three operational recycle pumps. It is

critical that the backwash recycle pumps be of

sufficient capacity to recycle the backwash water

with a one to two hour period to allow for each filter to be backwashed consecutively without

exceeding basin capacity.

TCEQ regulates recycled flows streams at water treatment plants. The flow may be returned to the

process at any point upstream of coagulant addition, which BWA WTP does.

1.4.3.7 Plant Residuals and Handling

The sludge generated during clarification is sent to two sludge basins onsite (highlighted in blue on

the figure below). Sludge from each clarifier is collected in a hopper and conveyed to one of these

basins. The decant water from these two basins can be sent back to the raw water pump header using

two dedicated pumps.

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The Plant has three sludge waste Gravity flow valves

and one standby pump. Currently, the sludge pumps

located by the clarifiers have been disabled so sludge

flows by gravity from the clarifiers to the sludge

basins.

The sludge basins and pumps are in fair condition.

Pump capacities are unknown so further

investigations will need to be completed to

determine if additional equipment will be required

to meet future demands.

1.4.4 Chemical Feed Systems As discussed above, BWA WTP adds several

chemicals to the water in order to meet their

treatment objectives. Chlorine, ammonia, and

chlorine dioxide are used for disinfection purposes. Alum or polyaluminum chloride is used as the

primary coagulant for treatment purposes. Cationic polymer is used as a coagulant and filter aid.

Anionic polymer is available for use as a coagulant aid. Other chemicals, including powdered activated

carbon, copper sulfate, fluosilicic acid and caustic, can be added for aesthetic or health reasons. This

section summarizes the configuration of these chemical feed systems and outlines recommended

improvements.

1.4.4.1 Chlorine

The BWA WTP uses chlorine for two purposes: to produce chlorine dioxide for disinfection and to

form chloramines for additional disinfection and distribution system residual. Chloramines are

formed by adding chlorine, in solution form, and ammonia to the water.

Chlorine is delivered by truck in one-ton cylinders that are stored in the area located in the chemical

building between the primary clarifiers. A monorail system is used to move cylinders inside the

building and for placement on scales adjacent to a manifold, through which chlorine gas is fed to

chlorinator units. The feed system is a vacuum feed system. Figure 1-2 is a photograph that shows the

chlorine cylinders. Three chlorinator units meter and control the amount of chlorine gas.

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Figure 1-2 Chlorine Cylinders at BWA WTP

The Plant is configured with the capability to apply chlorine solution at the splitter box, prefiltration,

and at the effluent junction box. The chlorine is equipped with a total of three vacuum chlorinator

units. The amount that can be withdrawn from any individual cylinder is limited by the vacuum

requirements of the chlorinators and the ambient temperature surrounding the chlorine cylinders.

The chlorinator room is equipped with a chlorine gas leak detector. TCEQ requires these detectors to

be installed in both the chlorinator room and chlorine storage room of these facilities to notify the

operators in the event of a leak. Additionally, TCEQ requires that either a full-face, self-contained

breathing apparatus (SCBA) or a supplied air respirator that meets Occupational Safety and Health

Administration (OSHA) standards and a small fresh bottle of fresh ammonia solution for testing be

readily accessible to each chlorinator room. SCBA are current located within the Control Room,

adjacent the Chlorine Storage area, and outside door of Chlorinator room. A one-ton repair kit is also

on-site at BWA.

Equipment capacities are unknown at this time so further investigations will need to be completed to

determine if additional equipment will be required to meet future demands.

1.4.4.2 Ammonia

The BWA WTP utilizes liquid ammonium sulfate (LAS) to react with the chlorine solution added to the

water to form chloramines. Although chloramines are less reactive than free chlorine for disinfection

purposes, chloramines produce lower levels of regulated disinfection by-products and a more stable

longer-lasting residual in the distribution system than free chlorine.

Under normal operating conditions, operations personnel feed the chlorine and ammonia at a ratio of

approximately 4:1. This may result in overfeeding ammonia at times if the chorine demand in the raw

water is high or if chlorine is consumed in the treatment process units.

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Tanker trucks deliver LAS to the chemical fill station at the chemical building. All bulk storage tanks

are located within concrete spill containment areas large enough to contain at least the volume of the

storage tank. The Plant has two ammonia feed pumps that have the capability to apply ammonia at the

splitter box and/or the effluent junction box. All equipment is in fair condition. Metering pump and

other equipment capacities are unknown at this time so further investigations will need to be

completed to determine if additional equipment will be required to meet future demands.

1.4.4.3 Chlorine Dioxide

BWA WTP has two on-site chlorine dioxide generating units, which combines sodium chlorite and

chlorine gas to create chlorine dioxide. The chlorine dioxide can be injected at the raw water intake or

into the splitter box prior to clarification. The chemical building houses one 6,400-gallon sodium

chlorite storage tank. Chlorine dioxide can be injected at the raw water line before the splitter box

and/or the raw water line at the intake. All equipment is in fair condition. Metering pump and other

equipment capacities are unknown at this time so further investigations will need to be completed to

determine if additional equipment will be required to meet future demands.

1.4.4.4 Polymer

BWA WTP has the option to add cationic polymer as a coagulant aid into the raw water pump header

at the raw water pump station. In addition, anionic polymer can be injected as a coagulant aid at the

splitter box. There is one 6,400-gallon low molecular weight (LMW) polymer storage tank holding

cationic polymer, which is in the chemical storage bay located by raw water pump station, and one

250-gallon high molecular weight (HMW) bin holding anionic polymer located inside main chemical

building. Two LMW polymer blending units convey the polymer through PVC pipe to be injected at the

raw water line before the splitter box and/or the raw water line at the intake. One HMW polymer

blending unit conveys the polymer through PVC pipe to be injected at the clarifier mixing chamber

and/or the filter influent pipe. All polymer equipment is in good condition. Metering pump and other

equipment capacities are unknown at this time so further investigations will need to be completed to

determine if additional equipment will be required to meet future demands.

1.4.4.5 Coagulant

The Plant has the option to add alum or polyaluminum chloride for coagulation. Both are injected in

the pump header at the Raw Water Pump Station. Coagulant is delivered to the Plant by trucks and

stored in two 10,000-gallon bulk storage tanks. Metering pumps are used for pumping the coagulant

to the application point.

1.4.4.6 Fluoride

BWA WTP has the capability to add fluoride to reduce tooth decay in the form of fluosilicic acid, also

called hydrofluosilicic acid. The dose must be carefully controlled to achieve an optimum finished

water level of approximately 0.8 mg/L. Higher levels can cause mottled teeth and low doses provide

no benefit. Fluoridation is not required by TCEQ.

Typically, fluoride is injected after filtration; however, it can also be injected into the raw water at the

head of the Plant. Although the recommended fluoride target residual (in the distribution system) is

approximately 0.8 mg/L, normally there is a small background concentration of fluoride in the raw

water, so the applied dose required to meet a residual of 0.8 mg/L typically ranges from 0.6 mg/L to

0.7 mg/L.

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1.4.4.7 Additional Chemicals

In addition to the above mention chemicals, BWA WTP also injects corrosion inhibitor at the effluent

junction box to help protect the distribution system piping. All corrosion inhibit piping is PVC, and the

chemical Bay houses one 6,400-gallon tank and one 55-gallon day tank of corrosion inhibitor and two

metering pumps. All equipment is in fair condition. Granular activated carbon can be injected at the

head of the Plant to help with color, taste and odor issues. However, it is not used very often and has

limited detention time available for effectiveness.

1.4.5 Disinfection BWA WTP currently uses chlorine dioxide and chloramines as the disinfectants. These systems were

discussed previously. This section outlines the current TCEQ approved CT study.

TCEQ has currently approved the CT study for the Plant, which dictates how much disinfection credit

the Plant can receive for a given set of water quality characteristics and disinfectant dose. Below

provides a brief discussion of the approved CT study and highlights any significant bottlenecks or

opportunities for improved disinfection performance.

The existing TCEQ approved CT study divides the Plant into four disinfection zones, D1 through D4,

with zone D2 having three subsections. The first zone consists of the raw water piping. The clarifiers,

clarifier piping and clarifier effluent boxes constitute the second zone; the filters, the third zone, and

the clearwell, clearwell piping and high service sump pump, the fourth zone. The majority of the

effective contact time (T10) at this Plant is contained in the second zone, D2. Table 1-12 details each

disinfection zone.

Disinfection Zone Treatment Unit

Volume (gallons)

Flow Rate (mgd)

Baffling Factor

T10 (min)

Unit Zone

D1 Raw water piping 16,394 17.967 1 1.314 1.31

D2A

Clarifier #1 (1) 841,562 5.085 0.3 71.501

72.38 Clarifier effluent drop box (1) 2,693 5.085 0.1 0.076

Clarifier piping 2,844 5.085 1 0.805

D2B

Clarifier #2 (1) 841,562 5.085 0.3 71.501

72.62 Clarifier effluent drop box (1) 2,693 5.085 0.1 0.076

Clarifier piping 3,672 5.085 1 1.040

D2C

Clarifier #3 (1) 1,341,873 7.798 0.3 74.342

75.08 Clarifier effluent drop box (1) 3,367 7.798 0.1 0.062

Clarifier piping 3,672 7.798 1 0.678

D3

Dual media filter #1 (1) 18,537 2.566 0.7 7.282

50.97

Dual media filter #2 (1) 18,537 2.566 0.7 7.282

Dual media filter #3 (1) 18,537 2.566 0.7 7.282

Dual media filter #4 (1) 18,537 2.566 0.7 7.282

Dual media filter #5 (1) 18,537 2.566 0.7 7.282

Dual media filter #6 (1) 18,537 2.566 0.7 7.282

Dual media filter #7 (1) 18,537 2.566 0.7 7.282

Dual media filter #8 (1) 18,537 2.566 0.7 7.282

D4

Clearwell influent piping (1) 22,740 17.967 1 1.823

25.49 Clearwell (new) (1) 532,187 17.967 0.5 21.327

Clearwell effluent piping (1) 25,697 17.967 1 2.060

High service pump sump (1) 34,542 17.967 0.1 0.277

Table 1-12 Summary of Disinfection Zones

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Table 1-13 summarizes the disinfection performance under cold-water conditions. The inactivation

ratio measures how much CT credit is achieved by the treatment process relative to how much is

required by TCEQ. Total values less than 1.00 indicate that the treatment process is not able to meet

regulatory requirements. TCEQ limits the allowable chlorine and chloramine residual to 4.0 mg/L.

Zone Disinfectant Chlorine

Residual (mg/L)

Inactivation Ratio

Giardia Viruses D1 Chlorine Dioxide 0.1 0.01 0.05

D2A Chlorine Dioxide 0.1 0.81 2.53 D2B Chlorine Dioxide 0.1 0.82 2.54 D2C Chlorine Dioxide 0.1 0.84 2.63 D3 Chlorine Dioxide 0.1 0.08 0.25 D4 Chloramines 3.0 0.11 0.18

Plant Total 1.02 3.01

As can be seen from the summary table above, the Plant will narrowly meet the disinfection CT

requirements for Giardia inactivation at rated Plant capacity and low temperature. This also assumes

that at chlorine dioxide residual can be maintained through the filters. Provisions for additional

downstream detention time for chloramine disinfection, such as an additional clearwell volume,

would provide a safety factor for meeting disinfection requirements.

1.4.6 Treatment Capacity Summary CDM Smith evaluated the capacity of each treatment process for the Plant to determine the Plant

capacity. Figure 1-3 summarizes the capacity of each treatment process. As shown in the figure, the

current Plant capacity is 17.97 mgd. Based on firm capacity, the limiting process is the clearwells,

followed by filtration and disinfection. (Disinfection is determined by CT study.) The clarification

process has the greatest amount of excess firm capacity, followed closely by the high service pumping.

Figure 1-3 Treatment Capacity Per Process

Table 1-13 Disinfection Performance at 17.97 mgd and 5° C

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1.4.7 Plant Electrical System This section summarizes the electrical evaluation of the existing electrical system at the BWA Water

Treatment Plant and proposes recommended improvements to correct any noted deficiencies and to

improve the electrical system reliability and Plant personnel safety.

1.4.7.1 Existing Condition

1.4.7.1.1 Overall Plant Electrical Distribution

The existing electrical power distribution system is a single bus radial system. The electric utility

serving this Plant is CenterPoint Energy. A single utility-owned overhead service comes to the Plant on

the north side of the property. The utility-owned pole mounted transformer steps-down the primary

voltage to the Plant distribution voltage of 4160V, 3-Phase. Backup power is provided from a

1500KVA, 4160V, 3-phase standby diesel engine driven generator located on the north side of the

property. Normal utility power terminates at a 4160V switchgear enclosure located near the electrical

building and generator. The generator power feed terminates at the second 4160V switchgear located

near the generator. Both feeders from the 4160V switchgear secondaries, then connect to a single bus

at the 4160V motor control center (MCC) located in the Electrical Building. The Generator Control

Panel monitors normal power and controls opening and closing of the 4160V switchgear breakers.

The switchgear breaker for the normal power is normally closed (NC), and the switchgear breaker for

the generator feed is normally open (NO). When normal power is lost, the generator control panel

opens the normal power switchgear breaker and closes the generator switchgear breaker. A

descriptive one-line diagram of the existing Plant’s electrical distribution is shown in Figure 1-4.

The Plant also has a 225A, 120/208V, 3-phase propane engine generator as a backup to serve some

critical loads at the Operation Building.

The Plant’s power system experiences intermittent voltage sags and surges or complete loss of power.

It appears that these events occur more often during lightning and thunderstorm events.

There is no up-to-date formal arc flash analysis performed for the electrical equipment. None of the

electrical equipment is labeled with the arc flash categories.

Other than the personal protection equipment (PPE) at the electrical building, there is no formal

implementation for the PPE requirements as defined by the Occupational Health and Safety

Administration (OSHA).

1.4.7.1.2 4160V Switchgear

The 4160V main and generator switchgear consist of a vacuum breaker assembly. The main breaker

has a remote breaker open/close operator panel to minimize the exposure to arc flash energy.

Both switchgears are over 20 years old and are in fair condition. However, the electromechanical

protective relays are obsolete and parts are not readily available.

1.4.7.1.3 4160V Motor Control Center

The 4160V MCC was installed in 1988. The branch protective devices are fusible load interrupter

switches. The fused interrupter switches serve 4160V-480V, 3-phase transformers for the VFDs that

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drive the High Service Pumps. The MCC also feeds the 750 KVA, 4160V-480V, 3-phase transformer,

which is the source of all the Plant’s 480V MCCs.

The 4160V MCC is in fair condition; however, replacement parts are often hard to obtain or no longer

stocked.

1.4.7.1.4 4160V Standby Generator

The Plant’s standby power source is a 4160 Volt diesel engine driven generator. The generator is rated

for 1500 KVA and has sufficient capacity to serve the Plant’s loads. There are two, 3,000-gallon diesel

storage tanks, which have enough capacity to run the Plant’s loads for two to three days.

The generator was installed around 1993 and is in good condition. It is located indoors on a raised

platform. The generator previously had vibration issues, but they have been corrected. The motorized

louver for the air intake does not open fast enough, resulting in a generator shutdown. The Plant has

provided a temporary solution leaving the roll-up door partially open with a bug screen blocking the

dust, bugs, and debris from entering the generator building.

1.4.7.1.5 480V Motor Control Centers

The 480V MCCs at the High Service Pumps Electrical Building, the Raw Water Pump Electrical

Building, and the Chemical Building are in good condition. They are installed in climate-controlled

buildings.

1.4.7.2 Proposed Improvements

1.4.7.2.1 Overall Plant’s Electrical Distribution

The existing 4160V MCC is proposed to be replaced with a split-bus system consisting of a Main-Tie-

Main (MTM) 4160V MCC. This means that the MCC has two main and tie breakers. During normal

operation the tie breaker would be closed and only the normal main breaker or the emergency main

breaker would be closed, but never both. Mechanical and electronic interlocks would be installed to

prevent the two main breakers to be in the closed position. If one side of the MCC is out of service, the

main breaker for that side would be open, and the tie breaker would be closed allowing the entire bus

to be serviced from one side only. The MTM configuration can also implement automatic transfer

controls (ATC) for the stand-by generator feed, eliminating the need for the upstream switchgears.

The MTM would have to be service entrance rated. A descriptive one-line diagram of the proposed

Plant’s electrical distribution is shown in Figure 1-5 on the following page. The existing electrical

equipment building would most likely have to be extended or a new building would have to be

installed to house the new 4160V MCC.

The proposed modification described above is considered the least expensive option compared to

other improvement types, such as dual utility feeds MTM system. The dual utility feeds MTM system

will improve the system reliability compared to the proposed system, but would require obtaining the

second utility feed from CenterPoint Energy. The feasibility of bringing the second utility service to the

plant would have to be investigated. Preferably the second utility service would be physically

separated from the main service, and would come from a different substation. BWA would have to

cover the entire cost for bringing the second utility service, if available. Since the plant has a back-up

generator, this step may not be necessary.

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It is recommended that the utility be contacted to investigate if the power quality issues at the Plant

are caused by external sources. Immediate improvements include installing surge protective devices

for power distribution equipment and UPS systems for the control power.

The National Electrical Code (NEC) requires that all electrical equipment be marked with a label to

warn qualified personnel of potential electric arc flash hazards. The warning labels are required to

state arc flash boundary, the incident arc energy, the safe working distance and the category of PPE.

Therefore, an arc flash analysis is recommended to determine the potential exposure to the arc

hazards in the electrical distribution system at the Plant.

1.4.7.2.2 4160V Switchgears

Because the existing switchgears are at the end of their useful life and replacement parts are hard to

find, it is recommended that both switchgears be replaced with new switchgears. It is recommended

that the new switchgears be equipped with vacuum breakers and solid-state relays with maintenance

setting. This improvement would increase the reliability of the electrical system and reduce the arc

flash category rating. However, if the 4160V MCC is replaced as recommended in Section 1.4.7.2.1

these switchgears are not required any longer.

1.4.7.2.3 4160V Motor Control Center

It is recommended that the 4160V MCC be replaced with a MTM type switchgear equipped with solid

state protective relays and vacuum breakers for both the incoming and the branch circuits. As

indicated in Section 1.4.7.2.1, the MTM configuration of this MCC would improve the system reliability

and serviceability.

1.4.7.2.4 4160V Standby Generator

The generator is in good condition and does not have to be replaced in the near future. It should

continue to be routinely serviced and maintained. The motorized intake louver is recommended to be

replaced to allow ample air entering the building and avoid nuisance generator shutdown.

1.4.7.2.5 480V Motor Control Centers

No improvement is required for the 480 Volt MCCs.

1.4.8 Instrumentation and Control CDM Smith visited the Plant to walk the site and review the state of the electrical and SCADA systems

currently installed at the plant. A conference call was also held with John Gross of Gross Solutions, the

Authority’s system integrator. The follow sections describe the current state of the SCADA system and

make recommendations for the future of the system.

1.4.8.1 Existing Conditions

The current SCADA system is an OPTO-22 system that was installed over the course of several years.

The system consists of 14 remote sites that communicate back over a cellular telemetry system to the

main system at the Plant. There are four remote terminal units (RTU) within the Plant that control

systems inside the Plant. The remote sites were installed during the period from 1998 to

approximately 2000. The RTUs in the Plant were installed approximately six to seven years ago.

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The existing OPTO-22 system uses the LC4 series of RTUs. The RTUs all seem to be in good condition

and the control panels that they are mounted in are all in climate controlled areas. The panels have

been kept neat and clean and this have attributed to the RTUs long life. The general condition of the

control wiring appears to be good and everything is well labeled.

The SCADA operator interface terminals are running OptoDisplay Runtime Version R4.1a with a build

date of January 20, 2005. The operating system is Windows XP Professional version 5.1.2600. The

Dell machine that is running the software is an Optiplex 360 that, according to Dell, shipped on August

20, 2009. The warranty on the machine expired on August 21, 2012.

The existing cellular telemetry system that connects the Plant to the remote water delivery sites uses

Dataremote CDS-9060 cellular modems. The Authority has service with Verizon. The modems use the

CDMA network and communicate data from the remotes sites back to the Plant using a serial protocol.

The system works well and the service has been reliable.

The system is being maintained by the system integrator, John Gross. Mr. Gross has clearly done an

outstanding job of maintaining the system as well as maintaining the system documentation. The

operations and maintenance staff have a great deal of confidence in Mr. Gross and his capabilities.

1.4.8.2 Proposed Improvements

The SCADA system in its current state is fully functional and in good condition. The components,

however, are all obsolete and finding replacement parts will be a challenge going forward. It is

recommended that the system be updated to newer, more easily available equipment to ensure parts

availability.

According to the Opto-22 Web site, the components used in the existing system have reached the end

of life and quantities are limited to stock on hand. It is recommended that the existing processors be

replaced with newer processors that are more readily available. If desired, other manufacturers of PLC

equipment could be evaluated to make the best selection. However, based on the Authority’s history

with the Opto-22 equipment and the service provided on that equipment by Mr. Gross, the best option

at the point seems to be updating to the newest Opto-22 model.

As a part of the Optp-22 upgrade it would be recommended to update to the latest version of the

software, PAC Display. The PAC Display software is compatible with Windows 7 so it would be

recommended to upgrade to Windows 7 since Microsoft is ending support of Windows XP on April 8,

2014. The operator terminals are using three year old Dell computers. Typically a computer can be

expected to last five to seven years. However, with the software upgrades being recommended it

would also be a good idea to upgrade the computers.

The existing cellular telemetry system is based on the Verizon CDMA system. Verizon is currently

moving away from the CDMA system and toward the LTE system. It would be recommended to

replace the cellular routers at the same time that the RTUs are being upgraded. A multiple band model

that would communicate both LTE and CDMA would be recommended to ensure that the system does

not become obsolete in the foreseeable future. It would also allow the new RTUs to communicate via

Ethernet rather than serial which would speed up data transfer.

1.4.8.3 Conclusion

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BWA has operated and maintained their current SCADA system in its current configuration for more

than six years. It has been well maintained and reliable. By incorporating these recommendations the

system can be updated to provide many more years of reliable service.

1.5 Proposed Improvements and Capital Costs Based on an evaluation of the existing plant process, mechanical, electrical and

instrumentation/SCADA system, a recommended capital facility plan has been developed. The

improvements include:

10 MG Clearwell

High Service Pump Station

Associated Yard Piping, Electrical and Instrumentation Improvements

Plant Electrical System Upgrade

System wide SCADA System Improvements

Capital cost information for the recommended improvement are shown in Table 1-14. The total

capital cost of the recommended improvements is approximately $14 million. A site plan showing the

location of the new clearwell and high service pump station is shown in Figure 1-6. It is

recommended that these improvements be scheduled for construction as soon as possible.

Item Description Quantity Unit Unit Cost Total

1.0 Process Mechanical Equipment

Clearwell, 10 MG 1 EA $3,120,000 $3,120,000

High Service Pump Station 17,500,000 GPD $0.20 $3,500,000

30” Yard Piping 1 LS $366,000 $366,000

Instrumentation (5%) 1 LS $156,000 $156,000

Electrical (20%) 1 LS $624,000 $624,000

Ancillary equipment and piping 1 LS $312,000 $312,000

Clearwell Foundation 1 LS $1,000,000 $1,000,000

Site Preparation 1 LS $100,000 $100,000

Subtotal: $9,178,000

2.0 Electrical

Demolition of existing 4160V switchgears, 4160V MCC, and appurtenances

1 LS $20,000 $20,000

New 4160V MCC 1 LS $380,000 $380,000

Cables, conduits, and miscellaneous 1 LS $110,000 $110,000

Perform coordination, short circuit, arc flash study, arc flash labels, and training

1 LS $20,000 $20,000

Subtotal: $530,000

3.0 Instrumentation and Control

Remote Sites 14 EA $32,100 $450,000

High Service DCU 1 LS $40,000 $40,000

Table 1-14 Proposed Probable Costs

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Raw Water DCU 1 LS $40,000 $40,000

Filter DCU 1 LS $40,000 $40,000

Master DCU 1 LS $40,000 $40,000

Computers and Software 1 LS $50,000 $50,000

Subtotal: $660,000

Construction Cost Total: $10,368,000

Contingency (20%) 1 LS $2,074,000 $2,074,000

Professional Services (15%) 1 LS $1,556,000 $1,556,000

Total: $13,998,000

APPENDIX A

Primary Drinking Water Regulations and Compliance

Status

June 2013

Technical Memorandum No. 1, Appendix A BWA WTP Regulations and Compliance Status

FA-1 Document Code

Table A-1 Primary Drinking Water Regulations and Current Compliance Status for BWA WTP Requirements Compliance Status

Filter Backwash Recycling Rule (FBRR)

Recycled flows (spent filter backwash, thickener supernatant and liquids from dewatering processes) must

be sent through all conventional or direct filtration processes, or to an alternate state-approved location.

Within compliance based on provided data.

Lead and Copper Rule (LCR)

AL of 0.015 mg/L for lead and 1.3 mg/L for copper; AL based on the 90th percentile of all tap water samples.

Exceeding an AL is not a violation, but can result in additional treatment and monitoring requirements.

Monitoring required at cold water taps in homes and buildings every six months, with the number of

sampling locations dictated by the population served.

Within compliance based on provided data.

Max copper level from 2008-2011 is 0.49 mg/L, with an

average of 0.033 mg/L.

Lead levels from 2008-2011 are less than 0.005 mg/L.

Stage 2 Disinfection Byproducts Rule (Stage 2 DBPR)

Bromate MCL - 0.010 mg/L; TTHM MCL - 0.080 mg/L; HAA5 MCL – 0.060 mg/L

Four distribution sampling points for each water treatment plant - one site with representative average DBP

levels from the Stage 1 DBPR monitoring sites, one with high HAA5 levels, two with high TTHM levels.

Basis for determining compliance is LRAA of quarterly samples (i.e., the TTHM and HAA5 standards must be

met at each sampling location).

One set of quarterly samples taken during the peak historical month for DBP levels.

Distribution system sampling points will be determined through an IDSE consisting of one year of

monitoring, about every 60 days, at eight sampling sites for each water treatment plant (in addition to the

Stage 1 DBPR compliance monitoring sites).

Systems with data sets available that meet EPA guidelines, or with sufficiently low DBPs (TTHM and HAA5

concentrations less than 0.040 mg/L and 0.030 mg/L, respectively) in all samples taken in the last two years,

are exempt from IDSE monitoring. IDSE monitoring deadlines vary by system size according to Table A-2.

Must meet new averaging requirements by the deadline shown in Table A-2. States may allow water

systems requiring capital improvements an additional two years to comply.

Within compliance based on provided data.

TTHM and HAA5 within limits at a max of 0.012 mg/L and

0.014 mg/L, respectively (Bromate data unavailable).

Sampling and monitoring within regulations.

Exempt from IDSE monitoring based on TTHM and HAA5

data provided.

Total Coliform Rule (TCR)

MCLG of zero for total coliforms, including fecal coliforms, Escherichia coli (E. coli).

MCL for total coliforms based on the presence or absence of coliforms, as follows:

Systems that collect at least 40 samples each month violate MCL if more than 5.0% of monthly samples are

total-coliform-positive.; Systems that collect less than 40 samples each month violate MCL if two or more

of the monthly samples are total-coliform-positive.

Systems violate the MCL if any repeat sample is fecal-coliform or E. coli positive.

Systems violate the MCL if any repeat sample is total-coliform-positive following a fecal-coliform- or E. coli-

positive routine sample.

Monthly monitoring within distribution system, with routine sampling depending on population served and water source. Repeat sampling is required for all routine samples that are total-coliform-positive. MCL bases compliance on monthly sampling results.

Within compliance based on provided data.

Technical Memorandum No. 1, Appendix A BWA WTP Regulations and Compliance Status

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Table A-1 Primary Drinking Water Regulations and Current Compliance Status for BWA WTP Requirements Compliance Status

Surface Water Treatment Rule (SWTR)

MCLG of zero for Giardia lamblia, viruses and Legionella.

Personnel meet state-established qualifications to operate all water systems.

Water systems reliably achieve the following:

At least 99.9% (3-log) removal and/or inactivation of Giardia lamblia between point where surface water

runoff does not recontaminate raw water and point downstream before/at first customer

At least 99.99%(4-log) removal and/or inactivation of viruses between point where surface water runoff

does not recontaminate raw water and point downstream before/at first customer.

Conventional water treatment systems meet the following turbidity requirements:

Combined filtered water turbidity must be less than/equal to 0.5 NTU in at least 95% of monthly samples.

Combined filtered water turbidity must never exceed 5 NTU [TCEQ: 5.0 NTU].

Conventional water treatment systems complied with the combined filtered water turbidity requirements

based on sampling performed at least once every four hours.

Filtered water turbidity standards in Interim Enhanced Surface Water Treatment Rule (IESWTR) have since

replaced the SWTR’s filtered water turbidity requirements.

Disinfection treatment process achieves at least 3-log removal and/or inactivation of Giardia lamblia and at

least 4-log removal and/or inactivation of viruses; system complies if it achieves a CT (disinfection residual x

effective contact time) value greater than the SWTR’s required CT value (CTreq).

Disinfectant residual concentration at the entrance to the distribution system cannot be less than 0.2 mg/L

[TCEQ: 0.2 mg/L free chlorine or 0.5 mg/L chloramine] for more than 4 hours. Compliance based on

continuous monitoring of disinfectant residual.

Disinfectant residual concentration in the distribution system cannot be undetectable [TCEQ: less than 0.2

mg/L free chlorine or 0.5 mg/L chloramine] in more than 5.0 percent of the samples each month, for any

two consecutive months. Compliance based on samples taken at same locations, times as bacteriological

samples collected under TCR.

Must achieve at least 0.5-log inactivation of Giardia cysts and 2-log inactivation of viruses by disinfection.

Within compliance based on provided data.

See IESWTR for compliance with turbidity standards.

Achieves at least 0.5-log inactivation of Giardia cycsts and

2-log inactivation of viruses based on 2011 CT study.

Interim Enhanced Surface Water Treatment Rule (IESWTR)

MCLG of zero for Cryptosporidium, set at the genus level (i.e., Cryptosporidium) rather than the species level

(i.e., C. Parvum).

Filtration water systems remove at least 99% (2-log) of Cryptosporidium between point where surface water

runoff does not recontaminate raw water and point downstream before/at first customer.

Conventional treatment or direct filtration water systems meet the following turbidity requirements:

Combined filtered water turbidity must be less than/equal to 0.3 NTU in at least 95% of monthly samples.

Combined filtered water turbidity must never exceed 1 NTU [TCEQ: 1.0 NTU].

Systems comply with combined filtered water turbidity requirements based on four-hour sampling intervals.

Within compliance based on provided data.

Annual avg TTHM/HAA5 below requiements so

disinfection profile not required.

Meets all turbidity standards.

All filtered water turbidity requirements met so filter

profile not required.

Disinfection profile not required because all 2011-2012

TTHM and HAA5 concentrations below limits.

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Table A-1 Primary Drinking Water Regulations and Current Compliance Status for BWA WTP Requirements Compliance Status

Conventional treatment or direct filtration water systems provide continuous turbidity monitoring of each

individual filter and report the following events to the state monthly:

Any individual filter with filtered water turbidity greater than 1.0 NTU in two consecutive measurements

taken 15 minutes apart.

Any individual filter with filtered water turbidity greater than 0.5 NTU at the end of the first four hours of

filter operation, based on two consecutive measurements taken 15 minutes apart.

If system cannot identify obvious reason for abnormal filter performance, must provide TCEQ with filter

profile within seven days.

If individual filter exceeds 1.0 NTU filtered water turbidity, based on two consecutive measurements taken

15 minutes apart at any time in each of three consecutive months, system must report the exception to

TCEQ and assess filter. If individual filter turbidity exceeds 2.0 NTU [TCEQ: any combination of filters

exceeding 2.0 NTU], based on two consecutive measurements taken 15 minutes apart at any time in each of

two consecutive months, system must report the exception and arrange for TCEQ or a third, TCEQ-approved,

party to perform a comprehensive performance evaluation.

Prepare "disinfection profile" if system's annual average TTHM concentration is 0.064 mg/L or more, or

annual average HAA5 concentration is 0.048 mg/L or more, based on samples taken in distribution system

over one year.

The system’s disinfection profile is based on daily monitoring conducted over a one- to three-year period;

must include historical inactivations of Giardia lamblia, and, for systems using chloramines or ozone, viruses.

Systems must measure daily disinfectant residual, disinfectant contact time, water temperature and pH

(where necessary).

Systems required to prepare disinfection profile must consult with the state before making one or more of

the following changes to their individual disinfection strategies:

Moving disinfectant application point (other than routine seasonal changes already approved by state);

Changing the type of disinfectant;

Changing the disinfection process; and

Making any other state-required change.

System must conduct sanitary surveys no less frequently than every three years for community systems, and

no less frequently than every five years for non-community systems.

Unfiltered systems control Cryptosporidium as part of the watershed protection program.

Water systems cover all facilities holding finished water for which construction began after February 16,

1999. [TCEQ: All facilities holding finished water must be covered.]

Technical Memorandum No. 1, Appendix A BWA WTP Regulations and Compliance Status

FA-4 Document Code

Table A-1 Primary Drinking Water Regulations and Current Compliance Status for BWA WTP Requirements Compliance Status

Long-Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR)

Applies only to surface water or groundwater public water systems under the direct influence of surface

water and serving fewer than 10,000 persons.

Does not apply to BWA

Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) Provide additional removal and/or inactivation of Cryptosporidium for source waters with more than 0.075

oocysts per liter, as Table A-4 shows.

Cover uncovered finished water reservoirs or treat the reservoir discharge to the distribution system to

achieve at least 4-log virus inactivation, unless approved otherwise by the state. [TCEQ: All facilities holding

finished water must be covered.]

Source water Cryptosporidium level (bin classification) for each water treatment plant will be the maximum

running annual arithmetic average for 24 months of monitoring, using EPA Method 1622/23 (total oocyst

count, uncorrected for recovery). Systems may collect at least 48 samples and use average of all samples.

Systems that have equivalent historical data or achieve at least 2.5-log removal/inactivation of

Cryptosporidium, in addition to conventional treatment, will be exempt from further monitoring. See Table

A-4 for additional removal and/or inactivation of Cryptosporidium.

If required, systems will achieve additional removal and/or inactivation of Cryptosporidium using methods

contained in a “microbial toolbox.” Table A-3 shows the components of the toolbox that the negotiating

committee developed.

Affected water systems will have three years following the initial bin classification to meet treatment

requirements associated with the bin. States may give water systems requiring capital improvements

another two years to comply. A second round of Cryptosporidium monitoring will be required six years after

the initial bin classifications are established. Table A-5 summarizes the compliance deadlines for this rule.

Within compliance based on provided data.

All facilities holding finished water are covered.

Monitoring protocols are as required.

Stage 1 Disinfection Byproducts Rule (Stage 1 DBPR) Chlorine MRDLGs and MRDLs - 4.0 mg/L and 4.0 mg/L, respectively

Chloramine (as Total Cl2) MRDLG and MRDL - 4.0 mg/L and 4.0 mg/L, respectively

Chlorine dioxide (as ClO2) MRDLG and - 0.8 mg/L and 0.8 mg/L, respectively

Chlorine/chloramines monitoring – same locations, time in distribution system as total coliforms

Chlorine/chloramines compliance – running annual arithmetic average, computed quarterly, of monthly

averages of all samples.

Chlorine dioxide monitoring – one sample/day/plant at entrance to distribution system; If daily sample

exceeds MRDL, additional samples are required in distribution system on following day.

Chlorine dioxide compliance – consecutive daily samples.

Rule allows for short-term increases of chlorine and chloramines if needed to protect public health or to

control specific microbiological problems.

TTHM MCL – 0.080 mg/L: Chloroform MCLG – 0 mg/L; Bromodichloromethane MCLG – 0 mg/L; Bromoform

MCLG – 0 mg/L; Dibromochloromethane MCLG – 0.06 mg/L

System within compliance based on provided data.

(Bromate and Chlorite data unavailable).

Monitoring protocols are as required.

Technical Memorandum No. 1 BWA WTP Existing Condition Evaluation

FA-5 Document Code

Table A-1 Primary Drinking Water Regulations and Current Compliance Status for BWA WTP Requirements Compliance Status

HAA5 MCL – 0.060 mg/L: Dichloroacetic acid – 0 mg/L, Trichloroacetic acid – 0.3 mg/L

Bromate – 0 mg/L MCLG, 0.010 mg/L MCL; Chlorite – 0.8 mg/L MCLG, 1.0 mg/L MCL

TTHM/HAA5 monitoring - Four samples/quarter/plant; One sample taken at location representative of

maximum residence time in distribution system; three at locations representative of system variability.

TTHM/HAA5 compliance - Running annual arithmetic average, computed quarterly, of quarterly arithmetic

averages of all samples.

Bromate monitoring - One sample/month/plant; applicable only for plants using ozone.

Bromate compliance - Running annual arithmetic average of monthly samples, computed quarterly.

Chlorite (monthly) monitoring - Three samples/month/plant; applicable only for plants using chlorine

dioxide. One sample taken near first customer; one at location representative of average residence time in

distribution system; one at location representative of max residence time in distribution system. Samples

must be collected on same day.

Chlorite (monthly) compliance - Monthly arithmetic average of samples.

Chlorite (daily) monitoring - One sample/day/plant; applicable only for plants using chlorine dioxide; sample

taken at entrance to the distribution system.

Chlorite (daily) compliance - Violation of MCL triggers additional distribution system monitoring.

Treatment or precipitative softening [TCEQ: all systems] remove DBP precursors, and thereby, reduce DBPs

by enhanced coagulation or enhanced softening, unless one or more of the following alternative compliance

criteria apply:

TOC concentration in raw water is less than 2.0 mg/L.

TOC concentration in treated water is less than 2.0 mg/L.

TOC concentration in raw water is less than 4.0 mg/L; alkalinity in raw water greater than 60 mg/L (as

CaCOз); and either TTHM and HAA5 concentrations in distribution system are less than 0.040 mg/L and

0.030 mg/L, respectively, with any disinfectant; or the water system has made a clear and irrevocable

financial commitment to technologies that will limit the levels of TTHMs and HAA5 in the distribution

system to less than 0.040 mg/L and 0.030 mg/L, respectively. [TCEQ: No provision for clear and irrevocable

financial commitment to technologies that will limit levels of TTHMs and HAA5 in the distribution system.]

TTHM and HAA5 concentrations in distribution system are less than or equal to 0.040 mg/L and 0.030

mg/L, respectively, with disinfection by chlorine only.

SUVA in raw water is less than or equal to 2.0 liters per milligram-meter (L/mg-m).

SUVA in treated water is less than or equal to 2.0 L/mg-m, where SUVA is determined in water before the

addition of disinfectants or oxidants. (Bench-scale testing is required for plants that add disinfectants or

oxidants before the treated water sampling point.)

Treated water alkalinity is less than 60 mg/L (as CaCO3) [TCEQ: and the system cannot meet Step 1 TOC

removal] for softening systems.

Magnesium hardness removal is greater than or equal to 10 mg/L (as CaCO3) [TCEQ: and the system

Technical Memorandum No. 1, Appendix A BWA WTP Regulations and Compliance Status

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Table A-1 Primary Drinking Water Regulations and Current Compliance Status for BWA WTP Requirements Compliance Status

cannot meet Step 1 TOC removal] for softening systems.

(Stage 1) DBPR allows states to approve alternative minimum TOC removal (Step 2) requirements for

conventional treatment systems that cannot reasonably meet the TOC removal requirements shown in

Table A-6. The alternative TOC removal (Step 2) requirement, which must be established by bench- or pilot-

scale testing, is the level at which additional coagulant reduces:

TOC removal to a rate of 0.3 mg/L per 10 mg/L alum addition or an equivalent addition of iron coagulant

(this is termed "point of diminishing returns"); or

pH to the enhanced coagulation Step 2 target pH shown in Table A-7.

Systems that use raw water with an alkalinity of less than 60 mg/L (as CaCO3), and for which small amounts

of alum or iron coagulant reduce the pH below 5.5 before significant TOC removal occurs, must add the

necessary chemicals to maintain the pH between 5.3 and 5.7 until the rate of TOC removal reaches 0.3 mg/L

per 10 mg/L alum addition or an equivalent addition of iron coagulant. Stage 1 DBPR also allows states to

waive enhanced coagulation requirements for systems that cannot achieve 0.3 mg/L TOC removal per 10

mg/L alum additions at all doses of alum or an equivalent addition of iron coagulant.

Systems comply with the enhanced coagulation and enhanced softening requirements based on the running

annual arithmetic average of monthly samples, computed quarterly.

Monitoring includes raw water TOC and alkalinity, and treated water TOC. Water systems must start

monitoring 12 months before the compliance deadline to take full advantage of the rule’s provisions for

alternative minimum Step 2 TOC removal requirements. [TCEQ: Water systems serving at least 10,000

persons must comply with monitoring and reporting requirements beginning January 1, 2001.]

Note: All compliance status statements are based on the data provided by BWA. Incomplete or inaccurate data provided could affect the compliance status noted.

AL = action level LRAA = locational running annual average TOC = total organic carbon

MCLG = maximum contaminant level goal IDSE = initial distribution system evaluation MRDL = maximum residual disinfectant levels

MCL = maximum contaminant level MRDLG = maximum residual disinfectant level goal TTHM = total trihalomethane

HAA5 = haloacetic acids NTU = nephelometric turbidity units

Table A-2 Compliance Timeline for Stage 2 DBPR

Public Water Systems

Actions Submit IDSE monitoring plan, system

specific study plan, or 40/30 certification Complete an initial distribution

system evaluation (IDSE) Submit IDSE

Report Begin subpart V (Stage 2) compliance monitoring

CWSs and NTNCWSs serving at least 100,000 October 1, 2006 September 30, 2008 January 1, 2009 April 1, 2012

CWSs and NTNCWSs serving 50,000 – 99,999 April 1, 2007 March 31, 2009 July 1, 2009 October 1, 2012

CWSs and NTNCWSs serving 10,000 – 49,999 October 1, 2007 September 30, 2009 January 1, 2010 October 1, 2013

CWSs serving fewer than 10,000 April 1, 2008 March 21, 2010 July 1, 2010 October 1, 2013

NTNCWSs serving fewer than 10,000 NA NA NA October 1, 2013

* States may grant up to an additional two years for systems making capital improvements.

Technical Memorandum No. 1 BWA WTP Existing Condition Evaluation

FA-7 Document Code

Table A-3 Microbial Toolbox for Additional Removal and/or Inactivation of Cryptosporidium

Toolbox option Cryptosporidium credits

Source Toolbox Components

Watershed control program 0.5-log credit. (Section 1.2.5.1)

Alternative source/intake management No prescribed credit. (Section 1.2.5.2)

Pre-Filtration Toolbox Components

Presedimentation basin with coagulation 0.5-log credit during any month that presedimentation basins achieve a monthly mean reduction of 0.5-log or greater in turbidity or state-approved performance criteria. Basins must operate continually with coagulant addition and all plant flow must pass through the basins. (Section 1.2.5.3)

Two-stage lime softening 0.5-log credit for two-stage softening where chemical addition and hardness precipitation occur in both stages. All plant flow must pass through both stages. (Section 1.2.5.4)

Bank filtration

0.5-log credit for 25-foot setback; 1.0-log credit for 50-foot setback. Aquifer must contain granular material and in at least 90 percent of the length of a core, grains less than 1.0 mm in diameter constitute 10 percent of the material. Average turbidity must be less than 1 Nephelometric Turbidity Unit (NTU). No presumptive credit for bank filtration that serves as pretreatment when source water monitoring is performed from the well (after bank filtration). (Section 1.2.5.5)

Treatment Performance Toolbox Components

Combined filter performance 0.5-log credit for CFE turbidity ≤ 0.15 NTU in at least 95 percent of samples each month. (Section 1.2.5.6)

Individual filter performance 0.5-log credit (in addition to the combined filter performance credit) for IFE ≤ 0.15 NTU in 95% of samples each month and no filter > 0.3 NTU in two consecutive measurements. (Section 1.2.5.7)

Demonstration of performance Credit based on demonstration to the state. (Section 1.2.5.8)

Additional Filtration Toolbox Components

Bag or cartridge filters (individual filters) Up to 2.0-log credit based on the removal efficiency demonstrated during challenge testing with a 1.0-log factor of safety. (Section 1.2.5.9)

Bag or cartridge filters (in series) Up to 2.5-log credit based on the removal efficiency demonstrated during challenge testing with a 0.5-log factor of safety. (Section 1.2.5.9)

Membrane filtration Log removal credit up to the removal efficiency demonstrated during challenge test if supported by direct integrity testing. (Section 1.2.5.10)

Second stage filtration 0.5-log credit for second separate granular media filtration stage if treatment train includes coagulation prior to first filter. (Section 1.2.5.11)

Slow sand filters 2.5-log credit as a secondary filtration step; 3.0-log credit as a primary filtration process. No prior chlorination for either option. (Section 1.2.5.12)

Inactivation Toolbox Components

Chlorine dioxide Log credit based on measured contact time (CT) in relation to CT table. (Section 1.2.5.13)

Ozone Log credit based on measured CT in relation to CT table. (Section 1.2.5.14)

UV Log credit based on validated UV dose in relation to UV dose table; reactor validation testing required to establish UV dose and associated operating conditions. (Section 1.2.5.15)

(For additional information see the designated Section from the LT2ESWTR State Implementation Guidance Document – EPA August 2007)

Technical Memorandum No. 1, Appendix A BWA WTP Regulations and Compliance Status

FA-8 Document Code

Table A-4 Additional Removal and/or Inactivation of Cryptosporidiuma

Bin Number Source Water Average Cryptosporidium

Concentration (oocysts/L) b Additional Cryptosporidium Removal and/or

Inactivation

1 <0.075 None

2 ≤0.075 and <1.0 1 log

3 ≥1.0 and <3.0 2 logs c

4 ≥3.0 2.5 logs c

a For conventional treatment plants that fully comply with IESWTR.

b Based on EPA Method 1622/23 and samples no less than 10 liters, uncorrected for recovery.

c Must include at least 1-log inactivation using ozone, chlorine dioxide, UV, membranes, bag/cartridge filters or in-bank filtration.

Table A-5 Compliance Timeline for LT2ESWTR

Systems that serve… ≥ 100,000 people

(Schedule 1)1 50,000 to 99,999

people (Schedule 2)1 10,000 to 49,999

people (Schedule 3)1

Submit: Sample Schedule and Sample Location Description July 1, 2006 January 1, 2007 January 1, 2008

Must begin the first round of source water monitoring by… October 2006 April 2007 April 2008

Submit Grandfathered Data (if applicable) December 1, 2006 June 1, 2007 June 1, 2008

Submit Bin Classification (Filtered) or Mean Cryptosporidium Level (Unfiltered) March 2009 September 2009 September 2010

Comply with additional LT2ESWTR treatment technique requirements2 April 1, 2012 October 1, 2012 October 1, 2013

Must being second round of source water monitoring by… April 2015 October 2015 October 2016

1 Your schedule is defined by the largest system in your combined distribution system.

2 State may allow up to an additional 2 years for capital improvements to comply with the treatment technique.

Table A-6 Step 1 Requirements for Removal of TOC by Enhanced Coagulation or Enhanced Softening a

Raw Water TOC (mg/L)

Raw Water Alkalinity (mg/L as CaCO3)

0 - 60 > 60 - 120 [TCEQ: ≥ 60 to 120] > 120b [TCEQ: ≥120]

> 2.0 – 4.0 [TCEQ: ≥2.0 - 4.0] 35.0% 25.0% 15.0%

> 4.0 – 8.0 [TCEQ: ≥ 4.0 - 8.0] 45.0% 35.0% 25.0%

> 8.0 [TCEQ: ≥ 8.0] 50.0% 40.0% 30.0%

a Percent removal is between raw water and combined filter effluent.

b Systems practicing softening must meet TOC removal requirements in this column.

Table A-7 Enhanced Coagulation Step 2 Target pH

Raw Water Alkalinity (mg/L as CaCO3) Target pH

0 – 60 5.5

> 60 – 120 6.3

> 120 – 240 7.0

> 240 7.5