Water Treatment Plant Slow Sand Filter Bed Operations and - - PowerPoint PPT Presentation

Water Treatment Plant Slow Sand Filter Bed Operations and Maintenance Presentation

Stayton Water Treatment Plant

Located at 200 North First Avenue

Water Treatment Plant Configuration

• Three ½ acre slow sand filter basins
• Control Room
• Monitors flow in, flow out, head loss, turbidity, and

PH in the ponds

• Adds 12.5% sodium hypochlorite for disinfection
• Adds soda ash to minimize corrosion in pipes due to

low PH

• Clear well
• Provides contact time to reduce chlorine in water

before leaving plant

Water Treatment Plant Map

Slow Sand Filter Configuration

Slow Sand Filter Bed

3 - 4 feet deep typical

Schmutzdecke (cleaning zone)

15-24 inches typical

Slow Sand Filter Beds

• Filter Beds 1 and 2 reconstructed in 1993
• Filter Bed 3 reconstructed in 2010
• Slow Sand Filter Beds use natural occurring processes

to clean water

• Tried and true and very reliable system
• North Santiam River is the source of Stayton water that

flows onto the slow sand filter beds

Slow Sand Filter Maintenance

• After a period of time of infiltrating water through the

sand the Schmutzdecke zone becomes less pervious

• When this occurs maintenance personnel drain the

water from the filter bed and skim off the top 1-inch of sand and remove it from the filter bed

• Each filter bed is skimmed approximately once every 8-

9 months

Slow Sand Filter Cleaning

Public Works crew skimming Filter Bed 3 Approximately 1-inch of sand is skimmed off the entire Filter Bed and removed

Slow Sand Filter Resanding Project

• In December while cleaning Filter Bed 1, a crew

member noticed pea gravel dispersed around the top

• f the sand
• Public Works engineers performed a survey on Filter

Beds 1 and 2

• Filter Bed 1 is in need of sand immediately
• Filter Bed 2 will need sand in the next 2 years
• Filter Bed 3 will need sand in the next 3 years

Slow Sand Filter Resanding Project

• Public Works put a Request for Bids out on March 4,

2019

• The bid opening is March 28th, 2019
• Engineers Estimate for the project is $650,000 -

$750,000

• This is an unplanned expense
• Project funding alternatives will be discussed by Andy

Parks, the City’s Financial Consultant

Financial Impacts Water System Slow Sand Filter Maintenance Project March 2019

Stayton Water CIP – Updated with sand filter capital 2019-2028

Water Fund Financial Projection Key Metrics FY 2019-2028 – full CIP; no borrowing

Water Fund Financial Projection Key Metrics FY 2019-2028 – full CIP; no borrowing

Water Fund Financial Projections FY 2019-2028 – full CIP; 5.0% annual rate adjustments through FY 2025; 3.5% after

Water Fund Financial Projection Key Metrics FY 2019-2028-including full CIP; incremental rates; borrowing

Stayton Water CIP – scaled back version 2019-2028 (used with 2.0% CPI rate adjustments only)

Water Fund Financial Projections FY 2019-2028 – scaled back CIP - 2.0% CPI rate adjustments

Water Fund Financial Projection Key Metrics FY 2019-2028 – 2.0% CPI rate adjustments

• nly; scaled back CIP

Summary

• Rate increases will be necessary to fund present level of service

and maintain sand filters

• If no borrowing – approximately a 35% increase is needed
• If borrowing of approximately $3.5 million during next 5 years,

rate increases of approximately 5.0%/year through FY 2025 will be necessary

• A comprehensive rate study may be desirable
• Rate components – can be looked at prior to a master plan update
• Revenue requirements will need to be updated after master plan update

Water Treatment Plant Slow Sand Filter Resanding Project

• Questions?