Study of Long-Term Options for Raspberry Falls and Selma Estates

Community Water Systems

January 30, 2015

Presentation Agenda

Project Background

Overview of Supply and Treatment Options

Supply and Treatment Option No. 1

Supply and Treatment Option No. 2

Triple Bottom Line Sustainability Analysis

Recommendation and Next Steps

Project Background

Treatment and pipeline supply options studied in 2011

Raspberry Falls-only treatment option selected

Monitoring results in May/June 2014 prompted renewed look

Preliminary screening of alternatives performed in September 2014

Loudoun Water requested Triple-Bottom-Line Sustainability Evaluation of the short-listed options

Financial

Environmental

Social

Overview of Supply and Treatment Options

Supply and Treatment Option No. 1

400 gpd/connection for potable use (196,400 gpd)

Combined facility located at Selma Estates

500 gpd/connection for irrigation supply

One irrigation supply system for Raspberry Falls (101,500 gpd)

One irrigation supply system for Selma Estates (138,500 gpd)

Supply and Treatment Option No. 2

900 gpd/connection for all water needs (441,900 gpd)

Combined facility would be located at Selma Estates

Supply and Treatment Option No. 1

Water supply

Existing Selma Estates wells used for potable supply

Existing Raspberry Falls wells used for irrigation supply

Two (2) new wells needed for Selma Estates irrigation supply

Treatment Techniques

Membrane filtration for pathogen/bacteria removal

Chlorine disinfection for virus/pathogen inactivation

Future GAC filtration allowance for SOC adsorption

Distribution System Improvements

New potable water booster pumps and irrigation booster pumps

New potable water storage tank and irrigation storage tanks

Irrigation distribution piping loops

Supply and Treatment Option No. 2

Water supply

Existing Selma Estates wells used for potable supply

Existing Raspberry Falls wells also used for potable supply

New raw water transmission main between Raspberry Falls and Selma Estates

Treatment Techniques

Membrane filtration for pathogen/bacteria removal

Chlorine disinfection for virus/pathogen inactivation

Future GAC filtration allowance for SOC adsorption

Distribution System Improvements

New potable water booster pumps

New potable water storage tank

Triple Bottom Line Sustainability Analysis

Criterion Type Criterion Criterion Scores

STO1 ‐ Combined Treatment with

Separate Irrigation

STO2 ‐ Combined Treatment for All

Uses

Economic Lowest Capital Cost 0 4

Environmental Lower Greenhouse Gas Emissions

2 0

Environmental Greater Aquifer Sustainability

2 0

Social Better Protection of Public Health

0 1

Social Better Quality of Life 0 1

Total Score (out of a possible 10 points) 4 6

Project Cost Estimates

Costs developed to Class 4 estimate level per the Association for the Advancement of Cost Engineering (AACE)

Accuracy level on the order of -15% to +30%

Supply and Treatment Option No. 1

Project cost estimate is $11.4 million

Range is $9.7 to $14.8 million

Supply and Treatment Option No. 2

Project cost estimate is $6.5 million

Range is $5.5 to $8.4 million