Water Treatment

Overview

Gabe Sasser

December 2016

Topics of Discussion

• Source Water Information

• Treatment Plants (History and Capacity)

• Water Quality

• Water Treatment Process

• Distribution System

• Conservation

Source Water Information

Water Source is Catawba River

• Lake Norman

• (32,475 acres)

• Mountain Island Lake

(2,788 acres)

Charlotte Water

Typical Raw Water Characteristics

Raw Water Quality • Turbidity 2-5 NTUS

• pH 6.8-7.3

• Alkalinity 16 mg/l

• Hardness 18 mg/l

• Color (apparent) 30

• Natural Fluoride 0.18 mg/l

Finished Water Leaving the Plant • Turbidity 0.15-0.20 NTU

• pH 8.2-8.8

• Alkalinity 19-25 mg/l

• Hardness 28-36 mg/l

• Chlorine 1.4-1.8 mg/l

• Color < 5 Color Units

• Fluoride 0.60-0.80 mg/l

Source Water Monitoring

• Phytoplankton & Chlorophyll

• Bromide analysis at intakes and throughout Mountain

Island and Lake Norman

• Inorganic monitoring throughout Mountain Island Lake

and Lake Norman

• Microbiological monitoring

Catawba River Pump Station

• Catawba River Pump Station can pump up to 350 million

gallons per day from Mountain Island Lake to

reservoir(s) at the Franklin WTP

• There are three major transmission lines that carry the

water to the reservoirs at Franklin

• Intake at Blythe Landing supplies gravity fed water to

Dukes water treatment plant in Huntersville

Catawba River Pump Station

Raw Main Diameters

• 54 Inches

• 60 Inches

• 120 Inches

Catawba River Pump Station

Source Water

• Pumped from CRPS to one of two 250 million gallon

reservoir at the Franklin Plant Site for storage

• This allow for pre sedimentation to occur

• Helps reduce turbidity which enhances filter run times

• This is approximately a 5 day supply

Hydrilla Control • Invasive aquatic weed in Mountain

Island and Lake Norman

• USDA Federal Noxious Weed list

• Clog intakes, reduce dissolved oxygen

• Underwater kudzu that colonizes at 10 feet or deeper

• Plant produces small potato like tubers in lake’s hydrosoil that can lie dormant for 10 years or longer

• Lack of vegetative growth does not mean eradication has been achieved

• Reproduces by fragmentation and tubers

• Tendrils can grow to 25 feet on a single plant

Hydrilla Control

• 12” Sterile Grass Carp

• Utilize biological control to keep Hydrilla from spreading in Lake Norman and Mountain Island Lake

• Sterile grasscarp (~$150/acre)

• Cost comparison per acre vs. mechanical harvesting ($2400) or aquatic herbicide ($800)

• Cost Share Program

• Annual stocking is required to account for fish mortality

Water Treatment Plants

Charlotte Water Has Three Water Plants

Three water treatment plants supply water to all areas of Mecklenburg county.

• Franklin (1959)

Capacity (181 MGD) Averages (80 MGD)

8 clearwells - 48 MG clearwell storage

• Vest (1924) Capacity (36 MGD) Averages (17 MGD)

3 Clearwells - 12 MGD storage

• Dukes (1998) Capacity (25 MGD) Averages (15 MGD)

3 Clearwells - 27 MGD storage

Built in 1959 Capacity: 181 million gallons per

day 12 Plant Operators

Upgrades and expansions every decade since it was built

Originally had 2 filters and 6 million gallons of finished water storage

22 filters and 48 million gallons of treated water storage

500 million gallons of raw water storage

Franklin WTP

Franklin WTP

Vest Water Treatment

Plant

Built in 1924

Original size 8 MGD

1934 expanded to 16

MGD

1948 expanded to 24

MGD

1949 first plant in

southeast to apply

fluoride to a public

water supply

Vest WTP

Lee Dukes Water Treatment Plant

Completed in 1998

Capacity: 25 million gallons per day

Ultimate build out of 108 MGD

7 Operators

Lee Dukes Water Treatment Plant

• Approximately 1.2 miles

from Blythe Landing

Intake to Dukes Plant.

• Water is conveyed

through a 60” diameter

raw water main.

Dukes Raw Water Main

Water Quality

Water quality is

analyzed at every stage

of the treatment stage

• Raw Water

• Settled Water

• Filtered Water

• Finished Water

• Distribution Water

Sample Analysis

PROCESS CONTROL TESTING

• pH- This is a measurement of the intensity of the basic or acidic condition of a liquid. A target pH is maintained in the distribution system to eliminate corrosion issues; pH adjustment is accomplished with lime, prior to leaving the treatment facility.

• Alkalinity- The capacity of water to neutralize acids. Alkalinity helps us determine how much coagulant must be applied to the treatment process for effective solids removal and is measured at various stages of treatment.

• Turbidity- The presence of suspended matter in water that causes cloudiness. This includes silt, fine clays, organic/inorganic materials and is measured at the raw water source , after filtration and at point of entry into the distribution system.

PROCESS CONTROL TESTING

• Iron/Manganese- Natural compounds that affect the taste of the water and cause discoloration; measured in milligrams per liter or parts per million.

• Chlorine Analysis- Colorimetric analysis to ensure chlorine concentrations are at target levels throughout the water treatment process

• Fluoride- Analyzed to determined the natural background concentration of fluoride present in the water and the final concentration in the water as it leaves the plant

Primary Standards

• Primary Standards - Maximum Contaminant Level (MCL) – The highest level of a contaminant EPA allows in drinking water that does not pose a short-term or long-term health risk.

Organic Chemicals (Synthetic and Volatile)

Disinfection By Products

Inorganic Chemicals

Radionuclides

Microorganisms

Revised Total Coliform Rule

Lead and Copper

Proposed revision to Lead and Copper Rule expected in spring of 2017 final rule will be implemented in 2018 or 2019

Secondary Standards

• Secondary Standards – These are non-enforceable

guidelines regulating contaminants that may cause

cosmetic effects or aesthetic effects in drinking water.

Iron 0.3 mg/L

Manganese 0.05 mg/L

Color <15 color units

Aluminum 0.05 mg/L

Sulfate 250 mg/L

Water Quality

• Water supplied by Charlotte Water is regularly tested

and achieves all water quality requirements set forth by

federal (EPA) and state (NCDEQ) authorities.

Water Treatment Process

Water Treatment Process

• All three of our water treatment facilities utilize a

conventional treatment approach of coagulation,

flocculation, sedimentation, disinfection and filtration.

Lake Reservoir

Storage Tank

Carbon

Chlorine

Fluoride

Lime

Aluminum

Sulfate

(Alum)

Chlorine

• Addition of activated

carbon (2-5mg/L)

• Reduces taste and odor

• Aids in coagulation and

the settling process

• Reduces potential for

DBP formation

Powdered Activated Carbon

• Aluminum sulfate (coagulant) is injected into rapid mix chamber

• A large mixer disperses the chemical through the water as it enters this chamber

• The addition of the aluminum sulfate lowers the pH to around 6.3-6.4

Rapid Mix

Coagulation

• Coagulation – clumping together of fine particles caused by reaction of coagulant chemicals with particulate matter within raw water

Aluminum Sulfate is utilized at all our facilities

Coagulant carries a positive charge while suspended particulate matter in raw water carries a predominantly negative charge

Charge neutralization causes particulate matter to clump together

Aids in separating solids from water

Flocculation

• Occurs after coagulation

• Involves gentle mixing of water

• Causes collisions to occur between clumped

particulate matter formed from coagulation

• Continues process of separating solids from

water

• The mixing chambers consist of large mixers that help form clumps out of the debris in the water

• As the water moves through the process, the mixing intensity is lessened

• Detention time is approximately 30 minutes at design capacity

Flocculation

• The water moves through this

area slowly in order for the

particles (floc) to settle out

• Mechanical raking system at

bottom of basin that

continuously removes sludge

buildup.

Sedimentation

Disinfection

• Chlorine is applied just prior to and just after filtration to

disinfect water and establish a free chlorine residual.

• Process to kill or inactivate most microorganisms in

water, including pathogenic bacteria.

Filtration

• Process that removes particulate matter from water

being treated

• Passes water though anthracite coal and sand to remove

particulate impurities

• Turbidity is reduced to <0.1 NTU

• Anthracite Coal

• Fine Sand

• Coarse Sand

• Small Gravel

• Large Gravel

Filter Media

Filter Media

• Filter Description:

• Anthracite Coal and Sand

• Anthracite Depth – 24 inches

• Sand Depth – 12 inches

Filtration Requirements

In 2015 all 3 water plants achieved Area Wide

Optimization Program standards for turbidity

• Water Treatment achieved filtered water turbidity of less

than 0.1 NTU 95% of time

• NCDEQ Combined filter turbidity standard is less

stringent requiring 0.3 NTU 95% of time

Post Filter Chemical Addition

• Upon exiting the filter,

additional chlorine is added to

the effluent water to establish

an optimal chlorine residual

level

• Fluoride is also added for

dental purposes

Post Filter Chemical Addition

• Hydrated Lime is

applied as a corrosion

inhibitor

• Increases pH, calcium

and alkalinity of water

• Passivates interior

surface of distribution

mains

Post Filter Chemical Addition

Clearwells

Clearwells are onsite,

treated water storage

structures at our plants

Franklin - 48 MG

Vest - 12 MG

Dukes - 27 MG

Franklin WTP

Distribution System

• Water pressure is mostly due to the elevation of storage tanks relative to the elevation of your home or business. In order to provide consistent water pressure, CLTWater has divided most of Mecklenburg County into three large water pressure zones.

• These zones allow CLTWater to provide water for fire emergencies and serve customers across large areas at various elevations.

Three Major Pressure Zones

Distribution System

• 279,609 active service connections

• 4,269 miles water mains

• 12 Tanks – 22.75 MG finished water storage space

2 Ground Storage (10 MG)

10 Elevated Storage (12.75 MG)

• 6 Booster Stations – Starita, Sharon, Hoskins, Plaza,

Idlewild, Sardis

• Highest volume pumped -169.23 MGD (8/20/07)

Conservation

Drought Protocol

• The Catawba Drought Management Advisory Group

(CW-DMAG) as of November 1st, have placed the

Catawba-River Basin in Stage 1 of the Low Inflow

Protocol (LIP).

• This is the second tier of five drought stage categories

and recommends voluntary conservation by water users

across the basin.

Conservation

Stage

Reduction Goal Charlotte Water

Activities

Voluntary

Actions

Mandatory

Actions

0

Watch

-Communications

-DMAG coordination

-Internal conservation

1

Voluntary

3%-5%

(157-262 gal/month per

typical user)

-Communications

-DMAG coordination

-Internal conservation

-City-wide conservation

Reductions:

-Discretionary water

uses

None

2

Mandatory

5%-10%

(262-524 gal/month)

-Communications

-DMAG coordination

-Internal conservation

-City-wide conservation

-Ordinance enforcement

Reductions:

-Community and

Business uses

Restrictions:

-Discretionary water uses

3

Extreme

10%-20%

(524-1047 gal/month)

-Communications

-DMAG coordination

-Internal conservation

-City-wide conservation

-Ordinance enforcement

-Industries asked to

implement

conservation plans if

not already doing so

Restrictions:

-Discretionary water uses

-Community & Business

uses

4

Emergency

Maintain essential water

uses & achieve lower

drought response stage

Communications

-DMAG coordination

-Internal conservation

-City-wide conservation

-Ordinance enforcement

-Assist Emergency

Management

Restrictions:

-Discretionary water uses

-Community & Business

uses

-Water use limited to

essential uses only

Stage 1 Drought Protocol

• Please conserve water use indoors and outdoors

• Only Irrigate Tuesday and Saturday (6pm -6am) Please refrain from outdoor water use during the day (6am -6pm)

to reduce evaporation losses

Try to limit landscape watering to no more than 1 inch of water per week including rain.

• Refrain from residential car washing

• Refrain from filling pools

• Refrain from residential pressure washing

• Please discontinue operation of fountains and other ornamental water features that do not sustain aquatic life

Up to Date Information Regarding

Drought Status

• CharlotteWater.ORG

• @CLTWATER

Questions?

Contact Information

Gabe Sasser

Water Quality Program Administrator

Charlotte Water

gsasser@ci.charlotte.nc.us

(704) 399-2142