Monitoring to Ensure Quality. Katie Kennedy-Fairfax Water

Transcription

1 Monitoring to Ensure Quality Katie Kennedy-Fairfax Water

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3 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)

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5 Started in the 70 s Discrete monitoring at high dam intakes Monitor Occoquan Reservoir upstream from intake Continuous monitoring with water quality buoys

6 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-tobottom

7 Oxygen diffused into hypolimnion from 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

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9 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

10 Monthly from Spring to Fall o o o 7 Sites marked w/mooring balls Pre/Post Season Copper Grabs (Pesticide Discharge Monitoring Plan) 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

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12 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

13 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

14 Option 1: Multiparameter sonde Pros: 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 sampler eg. 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

15 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

16 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 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

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