Monitoring to Ensure Quality

Katie Kennedy-Fairfax Water

Virginia’s Largest Water Utility (1 in 5 Virginians on Public Supply) One of 25 Largest Water Utilities in the Country Nearly 2 Million Retail and Wholesale Customers

Serving Fairfax County as well as municipalities of Loudoun, Fairfax City, Falls Church, Alexandria, Prince William, Herndon and Vienna

Recent Acquisition of Distribution system in City of Fairfax and City of Falls Church (Washington Aqueduct)

Two Treatment Plants and Two Sources (Potomac River and Occoquan Reservoir)

www.FairfaxWater.org

Started in the 70’s

Discrete monitoring at high dam intakes

Monitor Occoquan Reservoir upstream from intake

Continuous monitoring with water quality buoys

Stagnant Water + Agricultural Runoff = Algal Blooms

Stratification in Spring/Summer Epilimnion (Top layer) Thermocline (Rapid Temp Change) Hypolimnion (Bottom layer) 3 Layers defined by temperature and

dissolved oxygen differences Denser cold water remains on bottom Top layer warms and forms

thermocline

Turn-Over & Destratification in Fall/Winter Top warm layer cools quickly and

becomes more dense, then falls and displaces less dense water layer

All layers eventually mix into one after temperature is consistent top-to-bottom

Oxygen diffused into hypolimnionfrom suspended system

The oxygen suppresses the release of soluble iron, manganese and phosphorus from bottom sediments

Helps the plant use less chemicals, improve TOC removal, reduce iron & manganese levels, have not had to treat the reservoir with algaecide since installation of HOS

Submersible pumps used to collect water samples to profile the 3 intake depths

Water Quality Determines Frequency of sampling

Field Parameters: D.O., pH, Temperature, Turbidity

Lab Parameters: Manganese, Nitrate, Iron

Monthly from Spring to Fall o 7 Sites marked w/mooring ballso Pre/Post Season Copper Grabs

(Pesticide Discharge Monitoring Plan)

o Post Treatment Copper Grabs

Lab Parameters: alkalinity, odors, nitrate, phosphate, planktonic algae, total & dissolved copper (as needed)

Field Parameters: dissolved oxygen, temperature, turbidity, pH, depth, secchi depth, and soon blue-green algae and chlorophyll

Onboard water quality sensors send data every 30 minutes to data logger

Anti-fouling paint and copper used to limit biofouling on equipment

*Data is only as reliable as your equipment is maintained!*

Allowed lab to reduce grab samples from weekly to monthly

Real-time data received 24/7

Wireless cellular modem on buoy data to base station computer in laboratory, where it is displayed graphically

Buoy graphs checked daily and notes taken on status

Mobile app access to real-time data for maintenance trips

Option 1:

Multiparameter sondePros: measures all data at once, can easily be run by one person

Cons: expensive to purchase, requires maintenance and calibration for reliability

Option 2:

Multiple Meters with a Depth samplereg. individual meters for parameters (pH, Turbidity, DO, Conductivity, etc), Depth Sampler

Pros: Lower Start-up Cost

Cons: More equipment to maintain & calibrate for field work; May take longer to perform sampling events

John boat/trolling motor or canoe instead of a larger boat Less maintenance cost

More difficult to work off of

Easier for shallow water

Discrete vs Online Monitoring Discrete samples taken more often can take

place of continuous on-line monitoring

Weigh cost of work-time vs. on-line instrumentation costs over time

Maintenance Boat: Oil Changes, Power Steering,

Cleaning, Registration, Winterizing, Storage, training

Trailer Registration, Maintenance Buoy PMs Sonde PMs Man-Power to perform

maintenance safely Emergency Repairs

Initial Start-Up Cost Boat Sampling Equipment Staff training Truck for Towing Crane to pull buoys off water Remote Monitoring Equipment Test/Historical Data to show what

is necessary for your utility