Water Treatment Overview - Charlotte Chamber · PDF file• This allow for pre...
Transcript of Water Treatment Overview - Charlotte Chamber · PDF file• This allow for pre...
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
(704) 399-2142