Case Study # 1

Implementation of Anti-Icing and Pre-wetting Techniques at the Cypress Bowl Ski Area

Overview

The Cypress Bowl ski area reduced its winter maintenance costs by 34% between March 2000 and March 2001 through the introduction of anti-icing and pre-wetting techniques. As a result of these changes, the maintenance crew reduced their annual salt and sand use, and the new practices resulted in an estimated 73% reduction in chlorides released to the environment.

Background

Pre-wetting is the process of adding a liquid to sand and/or salt before it is applied to the road surface. Pre-wetting begins the dissolving process and increases salt adherence when it is applied, resulting in faster melting action and better retention rates on the road surface. Users estimate that pre-wetting can result in a 20 to 25% reduction in salt use.

Anti-icing is the application of a de-icer before or early on in a storm to dissolve with the precipitation and to prevent ice from bonding with the road surface. With anti-icing, a smaller amount of chemical is required to prevent the bond from forming than if the chemical were applied to an existing compacted layer of snow and ice. Timing of application is a critical factor in anti-icing, and therefore this technique relies on accurate and up-to-date weather information.

In recent years, the Cypress Bowl ski area began exploring new techniques and practices in winter maintenance to achieve cost reductions and other indirect benefits. This case study considers benefits and costs in evaluating the experience of Cypress Bowl with respect to changes in its winter maintenance program. The data and information used in this case study were provided in a report¹ prepared by Ice and Snow Technologies, LLC, (Limited Liability Company), for the Insurance Corporation of British Columbia (ICBC) on the Cypress Bowl ski area.

¹ Cypress Bowl Liquid Chemical Case Study, Ice and Snow Technologies, LLC, May, 2001.

Description of Winter Maintenance Practices

In spring 2000, Cypress Bowl began changing its winter maintenance strategy in cooperation with ICBC’s Road Sense safety program. First, winter maintenance workers were provided with training² which focused on how de-icing chemicals work. In the winter following the training, the maintenance crew shifted from its traditional use of road salt and sand, towards the use of anti-icing and liquid chemical pre-wetting strategies.

This shift in policy resulted in the following operational changes:

Benefits and costs assessment

March 2000 and March 2001 were very similar in terms of weather severity, and consequently allow for a good comparison of benefits and costs associated with the change in winter maintenance strategies at Cypress Bowl. The winter index value for March 2000 was -12.30 as compared to -11.26 for March 2001.³ Closer examination reveals that March 2001 was slightly milder in terms of the number of snow and freezing days; however, ten frost days were reported in both months. In drawing conclusions from the cost-benefit analysis, we must keep in mind that the difference in weather may slightly bias the results in favour of the liquid chemical winter maintenance strategy.

Figure 1: Comparison of winter maintenance costs at Cypress Bowl

Under the new liquid chemical winter maintenance strategy, Cypress Bowl saved approximately $21,500 in winter maintenance expenditures in March 2001 while: (a) maintaining its required level of service, and (b) responding to weather conditions similar to those in March 2000. These savings of approximately 34% were comprised of reductions in the total cost of: materials (39%), labour and equipment operation (27%), and equipment maintenance (81%).

² Training was provided and paid for by ICBC’s Road Sense Safety Program. Because the impact on Cypress Bowl is the focus of this case study, the cost of training was not included in the benefits and costs assessment. Additional costs incurred by training participants (e.g., travel) were also not considered.
³The weather index ranges from -50 (severe) to 50 (mild). Source: Road Weather Information Systems Volume 1: Research Report, SHRP-H-350, Strategic Highway Research Program, Sept, 1993.

Materials

While there was an increase in materials cost associated with the introduction of a new material (magnesium chloride), the cost savings from the reduction in the quantity of salt and sand use outweighed this expenditure. The report from Ice and Snow Technologies attributes this net reduction in materials cost to a more efficient operation with less wastage due to the use of liquid chemicals.

Labour and equipment

Cost savings in labour and equipment operation were approximately 28%. Some of these savings may be a result of the phasing out and replacement of older, less efficient equipment. All but two of the pieces of equipment were in operation for fewer hours in March 2001 as compared to March 2000⁴ . However, the report from Ice and Snow Technologies credits a portion of these savings to the reduced patrol times required under the liquid chemical strategies.

⁴ The two exceptions were the SB73/CB76 Sicard Blower and the PT96/CB48 Freightliner Truck, which experienced increased usage of 45% and 8% respectively. Note that the substantial increase in use of the Sicard Blower is likely due to the removal of another model of Sicard Blower from service.

Maintenance

Cypress Bowl also avoided approximately $10,000 in corrosion-related maintenance expenditures in the 2000-2001 winter season, $6,000 of which is likely attributable to the use of magnesium chloride in place of the more corrosive road salt. Inspections revealed less corrosion to equipment, and consequently several maintenance measures normally completed on an annual basis were not required. The figures presented in Table 1 are a prorating of these annual maintenance expenditures over the 5-month winter season.

Equipment upgrades

In order to implement the changes in winter maintenance practices, Cypress Bowl invested in two pre-wetting kits for its spreaders, one liquid application system, and one storage tank with miscellaneous fittings, for a total cost of approximately $60,000. The equipment upgrade figures presented in Table 1 are rough estimates of the amortized capital costs attributable to March 2001⁵.

In addition to the costs and cost savings discussed above, it is likely there will be long term benefits to the environment and motorist safety that cannot be evaluated/monetized using the data presented in the study. Ice and Snow Technologies, LLC estimates that the change in winter maintenance practices at Cypress Bowl resulted in a 73% reduction in the release of chlorides between March 2000 and March 2001 ⁶. This should result in a positive impact on the surrounding environment.

There is some evidence to suggest that liquid chemicals are not only more economical, but also more effective in maintaining safe roadway conditions for motorists. In this case, with a sample size of a single month, the difference in the number of motor vehicle incidents is too small to draw significant conclusions.

Conclusions

By adopting anti-icing and pre-wetting techniques that substitute magnesium chloride for sand and salt, Cypress Bowl was able to simultaneously reduce its total winter maintenance expenditures in March 2001 by approximately 34%, while providing (to some extent) indirect benefits to the natural environment and motorists. The use of liquid chemicals at Cypress Bowl is an example of best practices in winter maintenance that may be transferable to maintenance operations in similar winter conditions elsewhere with comparable benefits and cost savings.

⁵ The calculations assume: (a) a useful life of 10 winter seasons for the prewetting kits and liquid application system; (b) a useful life of 15 winter seasons for the storage tank; (c) a salvage value of zero for all equipment upgrades; and (d) a winter season lasting approximately 5 months each year.
⁶ This takes into account both the decrease in chloride release associated with reduced salt use, as well as the increase in chloride release associated with the introduction of magnesium chloride.

For Further Information:

Contact:
Dale Keep, President
Ice and Snow Technologies, LLC
Phone: 509-525-3197
Fax: 509-526-4394
Email: dalekeep@innw.net

Websites: http://www.iceandsnowtechnologies.com/cypress.html

Case Study Author: Environment Canada

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