Central Massachusetts Regional Stormwater Coalition

Part 7

Sand and Salt Calibration

September 26, 2013

Community Innovation Challenge Grant2013

Central Massachusetts Regional Stormwater Coalition

Why did CMRSWC Address This?

1. Focus on chloride impairments is strong in NH, along I-93 corridor.

2. Increased R&D into new deicing materials and methods in recent years.

3. Project partner Oxford, MA had developed detailed calibration procedure, reduced total chloride application and cost. Other Towns interested in learning how they did it.

Central Massachusetts Regional Stormwater Coalition

Objectives of the TaskOriginal: • Develop a “decision tree” that would use information

such as traffic conditions, pending weather, ambient temperature, and material melting temp to recommend loading (lbs per lane mile)

Revised: • Captured “decision tree” information done

elsewhere.• Developed “rough” loading estimate. • Documented Oxford’s detailed procedure.

Central Massachusetts Regional Stormwater Coalition

“Rough” Loading Estimate

• Input required for method: - Total material used in year (tons and gallons)- Total lane-miles managed- Number of storm days (days deicing was completed)

• Output: estimated pounds of chloride per lane mile.

Disadvantages: doesn’t account for variation in loadings from different vehicles or differences in storm

events; storm days not always known.

Central Massachusetts Regional Stormwater Coalition

“Rough” Loading Estimate: Example

Central Massachusetts Regional Stormwater Coalition

Calibrated Loading Calculation• Benchmarks loading from each vehicle; sum entire

fleet• Input required for method:

- Material weight/volume, distance traveled in one trip, and settings on each device for that vehicle.

- Alternately: set up tarp, time device for five minutes and extrapolate.

• Output: estimated pounds of chloride per lane mile for that vehicle.

Disadvantage: Time consuming.Advantage: Very accurate.

Central Massachusetts Regional Stormwater Coalition

Calibrated Loading Calculation: Example

Central Massachusetts Regional Stormwater Coalition

Once Application is BenchmarkedCurrent Chloride Loading(pounds of chloride per

lane-mile)

Suggested Recommendation

0 - 300 This loading rate is protective of water quality.

301 - 500

This loading rate is above-average.It is likely that chloride loading can be reduced without

adversely impacting public safety.Re-calibrate equipment to deliver 90% of current loading rate.

Make additional reductions on an iterative basis.

> 500

This loading rate is elevated.It is likely that chloride loading can be reduced without

adversely impacting public safety.Re-calibrate equipment to deliver 80% of current loading rate.

Make additional reductions on an iterative basis.

Central Massachusetts Regional Stormwater Coalition

Calibrated Loading Calculation

• Choose a target delivery rate. • Review and document settings on each application

device on vehicle. • Adjust settings to reduce delivery toward target. • Test reduced delivery rate during storm event, ensure

that public safety is not impacted. • Continue to recalibrate and make additional

reductions on an iterative basis.

Central Massachusetts Regional Stormwater Coalition

Other Salt Application Resources

Minnesota “Clipboard

Sheet”

Central Massachusetts Regional Stormwater Coalition

Other Salt Application Resources

Cornell Application

Rates