Evaluation of Management Alternatives for Truck Wash Water Generated During Winter Maintenance Activities

Abstract

The purpose of this research was to identify alternative strategies for managing wash water generated during routine washing of salt trucks at Ohio Department of Transportation (ODOT) maintenance facilities lacking access to sanitary sewer and to assess their costs. Eighteen potential management strategies were identified and evaluated. Six of these strategies were included in a detailed cost analysis, which indicated that site-specific conditions directly affect the cost of alternative management strategies and that tying a facility into the sanitary sewer is not always the most cost-effective strategy. For a county maintenance facility with 12 trucks and 30 winter events, tying into the sanitary sewer was the most cost-effective strategy when the capital cost was less than US$173,640; however, when the capital cost was greater than US$285,333, four of the five alternative strategies identified were more cost-effective than tying into the sanitary sewer.

Keywords

winter maintenance wash water management brine water reuse management costs

According to the Federal Highway Maintenance Administration, US$2.3 billion are spent by states annually for snow and ice removal (U.S. Department of Transportation, Federal High Way Administration, 2012). In Ohio, approximately US$50 million are spent on snow and ice removal annually, accounting for almost half of the annual operating budget. An average of 600,000 tons of salt is used to maintain Ohio’s 43,000 lane miles each year (Ohio Department of Transportation [ODOT], 2011). Due to the corrosive nature of sodium chloride, salt trucks are washed frequently at ODOT’s 88 count and 136 outpost garages during the winter months (Figure 1). Waste water generated during routine truck washing has elevated concentrations of suspended solids, dissolved solids, oil and grease, and heavy metals (Alleman et al., 2004; Fitch, Smith, & Bartelt-Hunt, 2004; Miller, Schneider, Kennedy, Parker, & Sullivan, 2012). In locations where sanitary sewer is available, truck wash water is treated with an oil/water separator and discharged directly. However, at facilities that do not have access to sanitary sewer, truck wash water must be collected and managed, often at significant cost to the Department of Transportation (DOT). Several methods of managing truck wash water have previously been identified (Alleman et al., 2004; Fitch, Craver, & Smith, 2006, 2008; Fitch et al., 2004).

Figure 1.

ODOT districts and garage locations.

The preferred management strategy of many state DOT is to tie existing facilities into the sanitary sewer system for the disposal of truck wash water, when possible. This option is not always available in rural locations, and the capital cost, which depends on the distance to a point of access to the sanitary sewer, can be high. However, this management option minimizes annual operating costs for truck wash water management and alleviates the need for ongoing collection, storage, and disposal of truck wash water.

Another potential option for managing truck wash water is to obtain a National Pollutant Discharge Elimination System (NPDES) permit for direct discharge of treated waste water (Fitch et al., 2006; Fitch et al., 2004). Prior to discharge, wash water would require treatment to reduce chloride ion concentrations below the U.S. Environmental Protection Agency (USEPA) National Secondary Drinking Water Regulation of 250 mg/L, or further, depending on local water quality standards (U.S. Code of Federal Regulations, 2002). Because chloride ion concentrations in truck wash water have been reported as high as 79,000 parts per million (ppm), this management approach would likely require desalination (Alleman et al., 2004).

Desalination technologies are generally divided into two groups: thermal technologies and membrane technologies. Because of their high energy costs, thermal technologies, such as distillation, are impractical for many state DOT maintenance facilities. Based on preliminary cost estimates, the Virginia Transportation Research Council (VTRC) identified reverse osmosis (RO) as the most cost-effective membrane system for use at the scale of a maintenance facility (Fitch et al., 2004). Pilot studies conducted to assess the ability of RO to treat truck wash water revealed several potential issues: (a) it is difficult to treat to less than 25 mg/L chloride, which could be the discharge requirement (per Virginia groundwater standards), (b) the volume reduction of the waste water was only 50%, and (c) pre-filtering was necessary because of the turbid water (Fitch et al., 2006).

One alternative to treating truck wash water to meet discharge requirements is to reuse the truck wash water for the production of brine that can be placed on the roadways as part of a winter maintenance program (Alleman et al., 2004; Fitch et al., 2008). Because many DOT already use brine as part of their winter maintenance program, reusing the wash water could yield cost savings in the form of reduced disposal and water costs.

Based on the concentrations of suspended solids, oil and grease, and dissolved solids in truck wash water, previous researchers have shown that truck wash water could be reused for the production of brine after a treatment process, including an oil/water separator and settling tank (Alleman et al., 2004; Fitch et al., 2008). Recent truck wash water quality monitoring at ODOT maintenance facilities has suggested that in addition to treatment with an oil/water separator, media filtration may be required to reduce heavy metals concentrations prior to reusing the wash water. Analysis indicated that copper and zinc concentrations in the wash water exceeded the level allowable for reuse, as set by the Ohio Environmental Protection Agency (OEPA) (Miller et al., 2012). Batch and column tests indicated that media filtration could be adequate to reduce the concentrations of these metals to acceptable levels for reuse (Miller et al., 2012).

Previous research has focused on reusing truck wash water for the production of brine because of the potential savings resulting from reduced material and disposal costs (Alleman et al., 2004; Fitch et al., 2008). In Ohio, it is unlikely that direct reuse (i.e., without treatment) of wash water would be a viable option because heavy metals concentrations in the water exceed the allowable levels for application on Ohio’s roadways (Miller et al., 2012). Alternative, cost-effective strategies for managing truck wash water are needed. Rather than seeking one option that will fit all maintenance facilities, the purpose of this article is to (a) identify a range of viable management options, (b) determine the factors that influence their cost, (c) develop a preliminary process for calculating annualized costs for each management option using site-specific garage information, and (d) evaluate the annualized costs for each alternative management option at ODOT maintenance facilities. The cost evaluation focused on comparing the cost of alternative management strategies with the cost of tying into the sanitary sewer system.

Method

Management Option Identification

Potential management options were identified through a combination of literature review, interviews with other state DOT personnel, and interviews with ODOT personnel. Thirty state DOTs were contacted to request their participation in a survey regarding best management practices for truck wash water management. The survey specifically addressed truck wash water disposal in locations lacking access to sanitary sewer, as well the benefits and limitations of reusing truck wash water. After the initial survey results were received, follow-up through telephone interviews were conducted with personnel from 17 state DOTs.

A combination of an e-mail survey, telephone interviews, and site visits were used to assess the current state of the practice of truck wash water management in Ohio. The e-mail survey, designed to collect information regarding wash water generation and disposal, number of trucks, brine production, and on-site storage volumes, was distributed to personnel within each of Ohio’s 88 counties (Figure 1) during winter 2011/2012. Survey information was confirmed, and additional information regarding current truck washing practices was collected during the telephone interviews and site visits.

A list of potential management strategies was compiled from the results of surveys and literature reviews. The list of potential options was narrowed based on feedback from maintenance personnel, a preliminary analysis of heavy metal concentrations in the truck wash water (Miller et al., 2012), and a preliminary assessment of the viability of reusing wash water based on a comparison of the volume of wash water generated with the volume of brine made. Data regarding the volume of brine made and the number of winter events (used to estimate the volume of wash water generated) in each of Ohio’s 88 counties was obtained from the ODOTs’ management database.

Identification of Cost Factors

To calculate the annualized costs of each management option, cost factors contributing to the total annualized cost of each option were identified and their values assigned or calculated using site-specific data, including the number of trucks at a facility and the number of winter events. Cost factors used in this analysis included storage, filtration, disposal, hauling, and water quality monitoring. A process for calculating disposal and hauling costs on a site by site basis was developed, as these costs depend on the volume of wash water generated and the distance to a disposal or reuse location.

Cost Calculation

The annualized cost of each management option was calculated using Equations 1 and 2. A discount rate of 7% was used for the cost analysis (Veneziano, Shi, & Ballard, 2010) and the value for n was governed by the management objective being assessed.

Calculation of annualized costs

Annualized Cost = Annualized Capital Cost + Annual Cost

Calculation of annualized capital costs

Annualized Capital Cost = Capital Cost \times [\frac{i}{({(1 + i)}^{n}) - 1}] + i,

where i = discount rate; n = number of years.

Results

Management Option Identification and Selection

Eighteen potential wash water management strategies, including reuse for the production of brine or truck washing, treatment with RO, and direct disposal at a waste water treatment plant (WWTP) were identified through the literature review and interviews with state DOT personnel. These options were narrowed based on feedback from DOT personnel. As a result of negative feedback from state DOT that tried reusing truck wash water for truck washing, this option was immediately eliminated as a viable management strategy for ODOT maintenance facilities. Treatment with an RO system was also eliminated because, at the salt concentrations measured in undiluted truck wash water (Alleman et al., 2004; Miller et al., 2012), RO treatment would still generate a significant volume of concentrated waste water (Asano, Burton, Leverenz, Tsuchihashi, & Tchobanoglous, 2007; Fitch et al., 2006) that would require disposal. Direct reuse (i.e., without treatment) of the wash water for the production of brine and application to Ohio’s roadways was also eliminated as a viable management strategy because copper and zinc concentrations in the wash water at ODOT maintenance facilities often exceed the concentrations allowable for reuse (Miller et al., 2012). Preliminary batch and column tests conducted to assess the effectiveness of media filtration for the removal of copper and zinc from truck wash water indicated that, with filtration, reuse may be a viable management option for ODOT (Miller et al., 2012).

Brine Use and Wash Water Generation

The annual volume of wash water generated varies among maintenance facilities based on the number of trucks and winter events. Because this volume is unknown, it was estimated for each ODOT maintenance facility using the site-specific number of trucks and number of winter events (based on the ODOT definition of a winter event, which depends on salt use), which are known historical quantities (Equation 3).

Estimation of the volume of wash water generated annually

\begin{array}{l} Annual Volume (gallons) = No . of Trucks \times Volume \\ per Truck per Wash Cycle \times No . of Wash Cycles, \end{array}

where Volume/Truck = 330 gallons/truck/cycle; Number of Wash Cycles = Number of Winter Events × 1.1.

To account for the fact that a truck may be washed more than one time during a winter event, the variable “wash cycle” was defined. Based on discussions with ODOT personnel, it was assumed that during a typical winter event, each truck goes through one wash cycle, and that approximately 10% of winter events will last multiple days, yielding additional wash cycles for those events. To calculate the annual number of wash cycles, the 3-year average number of winter events at each facility (as provided by ODOT) was multiplied by 1.1. To estimate the volume of wash water generated per truck in one wash cycle, wash times and hose flow rates, as reported by ODOT personnel, were used. The majority of garages reported hose flow rates in the range of 4 to 6 gallons per minute and wash times ranging from 30 to 90 min. Based on these parameters, it was estimated that an average of 330 gallons of wash water are generated by each truck during one wash cycle.

To verify the estimate of 330 gallons of wash water per truck per cycle, the water bills for the garages in ODOT District 10 were used. Water bills were obtained for each garage for the period of July 2010 through June 2011. The annual volume of wash water generated was estimated at each of these facilities as shown in Equation 3. The estimated volume was then added to the actual volume of salt brine made during winter 2010-2011 and compared with the actual volume of water used from October 2010 through March 2011, as reported in the water bill. This approach assumes that truck washing and brine production account for the majority of water usage at these facilities during the winter months, and that the amount of water consumed by garage staff for personal use is insignificant in comparison (U.S. Geological Survey, 2013). The estimated volume of water used in District 10 during winter 2010 was 1,537,092 gallons. The actual volume of water used during winter 2010 was 1,517,584. This suggests that the 330 gallons per truck per wash cycle estimate is reasonable.

The estimated volumes at each garage within a District were summed to obtain the total estimate for each District, and the District estimates were summed to obtain the estimated total annual volume of wash water generated by ODOT. These volumes were then compared with the 5-year average volume of brine made in each District to evaluate the viability of reusing truck wash water for the production of brine.

Figure 2 shows a graphical comparison of the estimated annual volume of wash water generated with the 5-year average volume of brine made in each ODOT District. The estimated annual volume of wash water generated by all ODOT garages for which data were available was approximately 19 million gallons, whereas the 5-year average volume of brine made by all ODOT maintenance facilities was approximately 6.5 million gallons. Based on these estimates, if all of the wash water generated at ODOT maintenance facilities were collected for reuse, at the current levels of brine use, approximately 12.5 million gallons of wash water would still require disposal. Although these estimates imply that widespread reuse as a strategy for the management of truck wash water would be impractical, the reuse of truck wash water at individual maintenance facilities may still be a viable option.

Figure 2.

Comparison of the volume of wash water generated in each of ODOTs’ 12 districts with the 5-year average volume of brine made.

Figure 3 shows the percent difference between the 5-year average annual volume of brine made and the estimated annual volume of wash water generated in each of Ohio’s 88 counties. For reuse to be viable at the current levels of brine usage, the percent difference between the volume of brine needed and the volume of wash water generated should be low. As shown in Figure 3, reuse may be a viable option in some, but not all, of Ohio’s counties.

Figure 3.

Percent difference between the 5-year average annual volume of brine made and the annual estimated volume of wash water generated in each of Ohio’s 88 counties.

Final Management Option Identification

After eliminating strategies that did not appear feasible for implementation at ODOT maintenance facilities, six management strategies were identified for detailed cost analysis. The strategies are shown in Figure 4 and are briefly summarized below:

Tie into sanitary sewer

Commercial disposal: Commercial disposal refers to the use of a contractor to pump and haul stored wash water for off-site disposal.

Disposal at a WWTP: This option refers to the collection and disposal of wash water at a WWTP using ODOT equipment (i.e., trucks) and personnel for hauling.

Disposal at a nearby ODOT maintenance facility: This option also includes the collection and off-site disposal of truck wash water using ODOT personnel and equipment for hauling. Instead of disposing of the wash water at a WWTP, this option assesses the cost of hauling wash water from one ODOT-owned facility to another ODOT-owned facility with sanitary sewer access for disposal. This option would require permission from the local sewer authority.

Media filtration and disposal at a nearby ODOT maintenance facility: This strategy incorporates treatment to reduce heavy metals concentrations prior to hauling to a nearby ODOT maintenance facility with sanitary sewer access for disposal. The need for media filtration would depend on the heavy metals concentrations in the truck wash water.

Media filtration and reuse for brine: This approach involves the treatment of truck wash water to reduce heavy metals concentrations prior to reusing the wash water for brine. The need for media filtration prior to reuse depends on the concentrations of heavy metals in the wash water as well as the local requirements for wash water reuse.

Figure 4.

List of potential management alternatives included in the detailed cost assessment.

Cost Factor Calculations

The values used in the cost analysis are shown in Table 1. Values for storage, filtration, and water quality monitoring were obtained from vendors. Costs for water quality monitoring were calculated based on the current required water quality monitoring program that has been implemented at ODOT’s Henry County Garage in District 2 for wash water reuse. The cost of disposal was calculated as the unit disposal cost multiplied by the estimated annual volume of wash water generated. Based on feedback from ODOT personnel, unit costs for commercial disposal, disposal at a WWTP, and disposal at an ODOT maintenance facility were assumed as US$0.30/gallon, US$0.05/gallon, and US$0.01/gallon, respectively.

Table 1.

Cost Values Used in the Calculation of Annualized Wash Water Management Costs.

Strategies	Capital		Annual
1. Sanitary sewer	Construction	Variable	Disposal	US$0.01/gallon
2. Commercial disposal	Storage	US$30,000	Hauling and disposal	US$0.30/gallon
3. Disposal at WWTP	Storage	US$30,000	Water quality monitoring	US$1,385
			Hauling	Variable
			Disposal	US$0.05/gallon
4. Disposal at ODOT garage with sewer access	Storage	US$30,000	Water quality monitoring	US$1,385
			Hauling	Variable
			Disposal	US$0.01/gallon
5. Filtration and disposal at ODOT garage with sewer access	Storage	US$30,000	Water quality monitoring	US$1,385
	Filtration unit	US$30,000	Hauling	Variable
			Disposal	US$0.01/gallon
			Media replacement	US$4,600
6. Filtration and reuse at County garage	Storage	US$30,000	Water quality monitoring	US$1,385
	Filtration unit	US$30,000	Hauling	Variable
			Media replacement	US$4,600

Note. All variable costs are calculated based on site-specific conditions. WWTP = waste water treatment plant; ODOT = Ohio Department of Transportation.

A process for calculating the hauling costs, which depend on the distance to the disposal or reuse location, was developed. Hauling costs were calculated as the cost of labor plus the cost to operate the vehicle during each trip to the disposal or reuse location. Labor costs were calculated as the cost of the driver multiplied by the time of each trip. To accurately determine the cost of the driver, the hourly wage was multiplied by 1.5 to account for salary and benefits (Bureau of Labor Statistics, 2012). Using an hourly wage of US$17/hr for a driver (ODOT District 2 personnel), a total hourly cost of US$26.35 was used in the labor cost calculation. The calculation assumed that approximately 1 hr would be required to load and unload the truck during each trip (based on a reasonable pumping rate), and that the average truck speed would be 45 miles per hour. Equation 4 shows the calculation of labor costs.

Calculation of labor cost

Labor Cost = (Distance / Speed + Time to Load and Unload) \times Labor Rate .

The cost of operating a truck to haul the wash water to a disposal or reuse location includes fuel, depreciation, purchase, insurance, maintenance, and permits. A diesel fuel cost of US$4.15 per gallon (U.S. Energy Information Administration, 2013), and an average fuel efficiency of 7 miles per gallon (Barnes & Langworthy, 2003) was used to calculate the unit cost of fuel as US$0.59/mile. An additional US$0.53/mile was added to the fuel cost to account for depreciation, purchase, insurance, maintenance, and permits (American Transportation Research Institute, 2011; Barnes & Langworthy, 2003; Trego & Murray, 2009), bringing the unit cost to operate a vehicle to US$1.12/mile (Table 2). This unit cost was multiplied by the roundtrip distance to the disposal or reuse location to calculate the total operating cost for each trip.

Table 2.

Costs of Operating a Commercial Vehicle.

Parameter	Cost (US$/mile)	Reference
Cost of vehicle	0.235	American Transportation Research Institute (2011)
Insurance	0.06	Trego and Murray (2009)
Repair/maintenance	0.105	Barnes and Langworthy (2003)
Tires	0.03	Trego and Murray (2009)
Depreciation	0.08	Barnes and Langworthy (2003)
Permits/licenses	0.023	Barnes and Langworthy (2003), American Transportation Research Institute (2011)
Subtotal	0.53
Fuel	0.59	U.S. Energy Information Administration (2013), Barnes and Langworthy (2003)
Total cost	1.12

To determine the total annual hauling costs, the number of trips to the disposal or reuse location was calculated based on the volume of wash water generated and the volume of storage available and multiplied by the hauling cost per trip. It was assumed that a 2,000 gallon tanker truck is available in each District for hauling wash water (based on feedback from ODOT personnel). The annual number of trips was calculated as the total estimated volume divided by 2,000 at garages with a storage volume of 2,000 gallons or greater. At these locations, the volume of the tanker truck limits the volume of wash water that can be hauled for disposal during each trip.

Cost Assessment

Baseline cost assessment

The first cost assessment of alternative management options was performed for a typical ODOT county garage, which was defined as a facility with 12 trucks and 30 winter events, and a typical ODOT outpost garage, which was defined as a facility with three trucks and 30 winter events. The most frequently reported number of trucks assigned to county and outpost garages, as reported by ODOT personnel, was used to represent the number of trucks at a typical facility. To determine the number of winter events at a typical facility, the spatial distribution of the 3-year average number of winter events (2008-2011) at ODOT’s 88 county garages was evaluated. Based on this analysis, 52% of county garages had a 3-year average number of winter events between 24 and 36, with a higher number of events in the northeastern part of the state, and fewer events in the southern part of the state. Because the number of winter events at outpost garages is not recorded by ODOT, it was assumed that the number of events at an outpost location was the same as the number of events at the county garage in the same county. Under this assumption, 72 of the 136 (53%) outposts had a 3-year average number of winter events between 24 and 36. Based on the results of this assessment, a value of 30 winter events was used to represent a typical facility.

An assumed capital cost of US$300,000 was used to calculate the annual cost of tying a typical facility into the sanitary sewer system. This was an average cost estimate for the installation of 6- to 8-inch diameter gravity service connections at tie-in distances ranging from 300 to 3,000 feet for three outpost locations in ODOT District 4. The annualized cost of tying into the sanitary sewer was calculated over a 40-year planning horizon, whereas the costs of the other management options were calculated over 12 years. The analysis also assumed that storage would be added to the garage, the roundtrip distance to a disposal or reuse location would be 55 miles, and a 2,000 gallon tanker truck would be used to haul the wash water.

Tables 3 and 4 show the estimated cost of alternative wash water management strategies for a typical county garage and a typical outpost garage. As shown in Table 3, the annualized cost to tie a typical county facility into the sanitary sewer would be US$23,810, whereas the annual cost to dispose of wash water at a nearby county garage would be US$14,330. Implementing off-site disposal, rather than tying into the sanitary sewer system, would yield an annual cost savings of approximately US$9,000. Pursuing off-site disposal at all 12 county garages currently lacking access to sanitary sewer, rather than tying these facilities into the sanitary sewer system, represents a potential annual cost savings of more than US$100,000.

Table 3.

Example of Cost Calculation for a Typical County Garage With 12 Trucks and 30 Winter Events.

	County garage
Management alternative	Annual cost for one county garage	Cost savings versus sanitary sewer	Annual cost savings for 12 county garages
Sanitary sewer	23,810
Commercial disposal	44,366	−20,556	−246,672
WWTP	19,557	4,253	51,036
Disposal at ODOT garage	14,330	9,480	113,760
Filtration and disposal	22,707	1,103	13,236
Filtration and reuse	21,400	2,410	28,920

Note. Analysis assumes a capital cost of US$300,000 for sewer tie-in and a hauling distance of 55 miles. The cost analysis assumed that filtration costs would be assessed to a facility with sewer access, whereas storage, hauling, and monitoring costs would be assessed to the garage lacking sewer access. WWTP = waste water treatment plant; ODOT = Ohio Department of Transportation.

Table 4.

Example of Cost Calculation for a Typical Outpost Garage With Three Trucks and 30 Winter Events.

	Outpost
Management alternative	Annual cost for one outpost	Cost savings versus sanitary sewer	Annual cost savings for 66 outposts
Sanitary sewer	22,829
Commercial disposal	14,963	7,866	519,156
WWTP	8,761	14,068	928,488
Disposal at ODOT garage	7,454	15,375	1,014,750
Filtration and disposal	15,831	6,998	461,868
Filtration and reuse	15,504	7,325	483,450

Note. Analysis assumes a capital cost of US$300,000 for sewer tie-in and a hauling distance of 55 miles. The cost analysis assumed that filtration costs would be assessed to a facility with sewer access, while storage, hauling, and monitoring costs would be assessed to the garage lacking sewer access. WWTP = waste water treatment plant; ODOT = Ohio Department of Transportation.

Table 4 shows the results of the baseline cost analysis for a typical outpost garage. The lowest cost option for an outpost garage under the conditions of this analysis would be disposing of wash water at a nearby ODOT facility, which had an estimated annual cost of approximately US$7,500. Pursuing off-site disposal, rather than tying into sanitary sewer, represents an annual cost savings of more than US$15,000 at each outpost location. For all 66 outpost facilities lacking access to sanitary sewer, this represents a potential annual cost savings of more than US$1 million.

Impact of volume and hauling distance on cost

To evaluate the impact of site-specific conditions, including the volume of wash water generated and the distance to the disposal location on the cost of each wash water management alternative, annualized costs were calculated for each management option using a high, typical, and low estimated volume and a short, typical, and long distance for hauling. The results of this analysis are shown in Tables 5 and 6. For the volume analysis, the capital cost of tying into the sanitary sewer was held constant at US$300,000 and the hauling distance was held constant at 55 miles. The low volume of 4,356 gallons of wash water was calculated by scaling the actual volume of wash water generated at an outpost location in ODOT District 4 for a facility with 2 trucks. The typical volume of 130,680 gallons was calculated for a facility with 12 trucks and 30 winter events, and the high volume of 309,276 was calculated for a garage with 12 trucks and 71 winter events, which was the actual number of winter events at the Ashtabula County Garage during winter 2010. As shown in Table 5, disposal at a nearby county garage was the most cost-effective option at low volumes, but tying into the sanitary sewer system becomes the most cost-effective management strategy at high wash water volumes. This analysis suggests that tying into the sanitary sewer is a cost-effective management strategy for larger facilities (i.e., with more trucks), but may not be the most cost-effective management approach for smaller, outpost garages generating low wash water volumes.

Table 5.

Evaluation of the Impact of the Volume of Wash Water Generated on the Cost of Each Alternative Management Option.

	Annualized cost (US$)				Cost savings
	Volume				Volume
Management alternative	Low	Typical	High	% increase in cost	Low	Typical	High
Sanitary sewer	22,546	23,810	25,596	14
Commercial disposal	6,469	44,366	97,945	1414	16,904	−20,556	−72,349
WWTP	5,642	19,557	39,231	595	17,078	4,253	−13,635
Disposal at ODOT garage	5,468	14,330	26,860	391	8,701	9,480	−1,264
Filtration and disposal	13,845	22,707	35,237	155	8,745	1,103	−9,641
Filtration and reuse	13,801	21,400	32,144	133	22,546	2,410	−6,548

Note. All analyses utilized a capital cost of US$300,000 to tie into the sanitary sewer. The cost savings were calculated as the annualized cost of sanitary sewer tie-in minus the annualized cost of the management alternative; negative values indicate that there is no cost savings by implementing an alternative management strategy. For the volume analysis, the low volume of 4,356 gallons was calculated using a garage with 2 trucks by scaling actual wash water volumes from an outpost garage in District 4; the high volume of 309,276 was calculated using 12 trucks and 71 winter events (actual number of events at Ashtabula County Garage during winter 2010); typical volume of 130,680 was calculated using 12 trucks and 30 events; distance was held constant at 55 miles roundtrip. WWTP = waste water treatment plant; ODOT = Ohio Department of Transportation.

Table 6.

Assessment of the Impact of Hauling Distance on the Annualized Cost of Alternative Wash Water Management Strategies at a Typical Outpost and County Maintenance Facility.

	County						Outpost
	Distance			Cost savings			Distance			Cost savings
Management strategy	Short	Typical	Long	Short	Typical	Long	Short	Typical	Long	Short	Typical	Long
Sanitary sewer	23,810	23,810	23,810				22,829	22,829	22,829
Commercial disposal	44,366	44,366	44,366	−20,556	−20,556	−20,556	14,963	14,963	14,963	7,866	7,866	7,866
WWTP	16,208	19,557	27,371	7,602	4,253	−3,561	7,924	8,761	10,714	14,905	14,068	12,115
Disposal at ODOT garage	10,981	14,330	22,144	12,829	9,480	1,666	6,617	7,454	9,408	16,212	15,375	13,421
Filtration and disposal	19,358	22,707	30,521	4,452	1,103	−6,711	14,994	15,831	17,785	7,835	6,998	5,044
Filtration and reuse	18,051	21,400	29,214	5,759	2,410	−5,404	14,667	15,504	17,458	8,162	7,325	5,371

Note. Cost savings represents the potential cost savings of each alternative management strategy when compared with the cost of tying into sanitary sewer. Negative values indicate that tying into sanitary sewer is more cost-effective. For the distance analysis, the short distance was 15 miles roundtrip; the typical distance was 55 miles roundtrip; and the long distance was 125 miles roundtrip. The volume was held constant at 130,680 for a county garage and 32,670 for an outpost garage. WWTP = waste water treatment plant; ODOT = Ohio Department of Transportation.

For the distance analysis, distances of 25, 55, and 125 miles roundtrip to the disposal location were used. The wash water volumes were held constant at 130,680 gallons for a county garage, and 32,670 gallons for an outpost, and the capital cost to tie into the sanitary sewer was held constant at US$300,000. Neither the cost of tying into the sanitary sewer nor the cost of commercial disposal is dependent on hauling distance. As expected, at longer hauling distances, off-site disposal and treatment become a less cost-effective management option (Table 6). For a typical outpost garage, the lowest cost management option, disposal at a nearby county garage, has a cost of approximately US$6,600 at a hauling distance of 25 miles, but the cost increases to US$9,400 at a hauling distance of 125 miles (Table 6). For a county garage, the lowest cost option, disposal at a nearby ODOT facility, has an annualized cost of approximately US$11,000 at a distance of 25 miles, but the annualized cost increases to more than US$22,000 at a hauling distance of 125 miles (Table 6). When compared with the cost of tying into the sanitary sewer, off-site disposal is always more cost-effective than tying into the sanitary sewer for a typical outpost when the hauling distance is less than 125 miles. For a typical county garage, the potential cost savings of off-site disposal at a roundtrip hauling distance of 125 miles may not be large enough to offset the increased complexity in logistics and planning required to pursue this option.

Impact of capital cost of sanitary sewer tie-in on cost

To evaluate the impact of the capital cost of tying into the sanitary sewer on the cost-effectiveness of this management strategy, the annualized cost of tying into the sanitary sewer was calculated for capital cost values ranging from US$100,000 to US$800,000. The annualized cost for the sewer tie-in at each value was then compared with the annualized cost of each alternative management option calculated for a typical county garage and a typical outpost garage. The hauling distance was held constant at 55 miles for this analysis. To assess the potential cost savings of implementing an alternative to tying into the sanitary sewer, the annualized cost of each management option was subtracted from the annualized cost of tying into the sanitary sewer. As shown in Figure 5, at a capital cost of US$100,000, tying into the sanitary sewer is the most cost-effective management strategy for a typical county garage; however, at a capital cost of US$600,000, it is the least cost-effective of the management options identified.

Figure 5.

Annualized cost savings that could be achieved by implementing an alternative to tying into the sanitary sewer at a typical county garage.

As shown in Figure 6, for a typical outpost garage, off-site disposal at a nearby county garage is always more cost-effective than tying into the sanitary sewer when the hauling distance is less than 55 miles. When the capital cost of tying into the sanitary sewer is US$200,000, all three of the off-site disposal strategies are more cost-effective than tying into the sanitary sewer (when hauling distance is less than 55 miles), and at a capital cost of US$300,000 to tie into the sanitary sewer, all of the management options identified are more cost-effective than tying into the sanitary sewer under the conditions of this cost analysis. This suggests that for outpost garages, there may be a more cost-effective strategy for managing wash water than tying into the sanitary sewer.

Figure 6.

Annualized cost savings that could be achieved by implementing an alternative to tying into the sanitary sewer at a typical outpost garage.

Conclusions

The purpose of this research was to identify potential options for managing truck wash water generated at ODOT maintenance facilities that do not have access to sanitary sewer, to assess their costs, and to compare the costs of alternative management strategies with the cost of tying into the sanitary sewer. Based on the results of a literature review, interviews with state DOT personnel, and water quality data collected at ODOT maintenance facilities during the winter of 2011/2012, the following six viable management options were identified for detailed cost assessment: tying into the sanitary sewer, use of a contractor to pump and haul wash water to a disposal location, collection and disposal of wash water at a WWTP, collection and disposal of wash water at a nearby ODOT facility, filtration and disposal, and filtration and reuse.

A preliminary assessment of the viability of reusing truck wash water generated at ODOT maintenance facilities was conducted. Estimation of the volume of wash water generated by ODOT maintenance facilities indicated that the volume of wash water generated (approximately 19 million gallons) by all ODOT maintenance facilities greatly exceeds the volume of brine used by ODOT in a typical winter (approximately 6.5 million gallons). This suggests that if reuse were implemented at all maintenance facilities, approximately 12.5 million gallons of wash water would still require an alternative management strategy. Although this option does not appear to be viable on a widespread scale, individual maintenance facilities may be able to implement successful reuse programs depending on the volume of wash water generated and the volume of brine needed.

Cost factors were identified for each management option, and their values determined through consultation with vendors and contractors. Processes for calculating variable costs, including hauling and disposal, were developed and used to calculate the annual cost of each wash water management option for typical ODOT county and outpost garages. Results showed that collecting and disposing of wash water at a nearby ODOT maintenance facility, rather than tying into the sanitary sewer, represents an annual cost savings of approximately US$9,000 at a county garage and US$15,000 at an outpost garage. Extrapolating these results to the 12 county garages and 66 outpost garages currently lacking access to sanitary sewer, implementing off-site disposal, rather than tying into sanitary sewer, represents a potential annual cost savings of US$1.1 million.

The influence of the volume of wash water generated and the hauling distance on the cost of each management option was assessed. The volume of wash water had a larger impact on the cost than hauling distance. At low volumes, all of the management options identified would yield a cost savings when compared with the cost of tying into the sanitary sewer, whereas at high volumes, none of the management options identified are more cost-effective than tying into sanitary sewer.

The cost-effectiveness of alternative management options also depends on the capital cost of tying into the sanitary sewer. Under the typical volume scenario for a county garage, at a capital cost of US$100,000, tying into the sanitary sewer is the most cost-effective wash water management strategy. At a capital cost of US$300,000, disposal at a WWTP, disposal at a nearby garage, filtration and disposal, and filtration and reuse become more cost-effective than tying into the sanitary sewer. For a typical outpost garage, which generates lower volumes of wash water, off-site disposal at a nearby county garage is always more cost-effective than tying into the sanitary sewer when the hauling distance is less than 55 miles. When the capital cost of tying into the sanitary sewer system is greater than US$300,000, all of the management options identified are more cost-effective than tying into the sanitary sewer under the conditions of this cost analysis.

This research suggests that tying into the sanitary sewer is not always the most cost-effective management strategy and that alternative strategies should be considered based on individual garage conditions. The volume of wash water generated, distance to the disposal location, and the capital cost of sanitary sewer tie-in are all factors that need to be considered in determining an ideal management strategy at individual garages.

Footnotes

Acknowledgements

The authors would like to thank the U.S. Department of Transportation (USDOT) and Ohio Department of Transportation for their generous support.

Authors’ Note

The research was performed at the University of Akron, and the contents reflect the views of the authors, who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or polices of the U.S. Department of Transportation or Ohio Department of Transportation.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Ohio Department of Transportation [State Job Number 134629].

Author Biographies

Christopher M. Miller is an associate professor in the civil engineering department at the University of Akron and a registered professional engineer in the State of Ohio. His research areas include winter maintenance transportation operations, including facilities and equipment management and material usage optimization to minimize corrosion and environmental impacts.

William H. Schneider IV is an associate professor in the civil engineering department at the University of Akron as well as a registered professional engineer in the State of Ohio. His research areas include traffic data collection, archiving, management and analysis; winter maintenance operations; and crash prediction and injury-severity modeling.

Marla J. Kennedy is a graduate student in the civil engineering department at the University of Akron. The focus of her dissertation is the use of machine learning algorithms for process optimization in drinking water treatment plant and winter maintenance.

References

Alleman

J. E.

Partridge

B. K.

Yeung

(2004). Innovative environmental management of winter salt runoff problems at INDOT maintenance yards. West Lafayette, IN: Joint Transportation Research Program.

American Transportation Research Institute. (2011). An analysis of the operational costs of trucking: 2011 update. Retrieved from http://www.atri-online.org/research/results/Op_Costs_2011_Update_one_page_summary.pdf

Asano

Burton

F. L.

Leverenz

Tsuchihashi

Tchobanoglous

(2007). Water reuse: Issues, technologies, and applications. New York, NY: McGraw-Hill

Barnes

Langworthy

(2003). The per-mile costs of operating automobiles and trucks. Minnesota Department of Transportation Office of Research Services. Retrieved from http://www.lrrb.org/media/reports/200319.pdf

Bureau of Labor Statistics. (2012). Employer costs for employee compensation, September 2012 (USDL-12-2404). Retrieved from http://webcache.googleusercontent.com/search?q=cache:http://www.bls.gov/opub/ted/2012/ted_20121219.htm

Fitch

M. G.

Craver

V. O.

Smith

J. A.

(2006). Potential use of reverse osmosis in managing saltwater waste collected at road-salt storage facilities (Report No. VTRC 06-R26). Charlottesville: Virginia Transportation Research Council.

Fitch

M. G.

Craver

V. O.

Smith

J. A.

(2008). Recycling of salt-contaminated stormwater runoff for brine production at Virginia department of transportation road-salt storage facilities (Report No. VTRC 08-R17). Charlottesville: Virginia Transportation Research Council.

Fitch

M. G.

Smith

J. A.

Bartelt-Hunt

(2004). Characterization and environmental management of stormwater runoff from road and salt storage facilities (Report No. VTRC 05-R15). Charlottesville: Virginia Transportation Research Council.

Miller

C. M.

Schneider

I. V.

Kennedy

M. W. H.

Parker

Sullivan

(2012). Snow removal waste water disposal alternatives (State Job No. 134629). Ohio Department of Transportation Office of Research and Development. Retrieved from http://www.dot.state.oh.us/Divisions/Planning/SPR/Research/reportsandplans/Reports/2014/Environmental/134629_FR.pdf

10.

Ohio Department of Transportation. (2011). Snow and ice practices. Division of Operations Office of Maintenance Administration: Ohio DOT. Retrieved from http://www.dot.state.oh.us/Divisions/Operations/Maintenance/SnowandIce/Snow%20and%20Ice%20Best%20Practices/ODOT%20Snow%20and%20Ice%20Practices%20March%202011.pdf

11.

Trego

Murray

(2009). An analysis of the operational costs of trucking. Retrieved from http://www.atri-online.org/research/results/ATRITRBOpCosts.pdf

12.

U.S. Code of Federal Regulations. (2002). National secondary drinking water regulations (Title 40, Protection of Environment, Chapter 1, Part 143). Washington, DC: Government Printing Office. Retrieved from http://www.gpo.gov/fdsys/pkg/CFR-2002-title40-vol1/content-detail.html

13.

U.S. Department of Transportation, Federal High Way Administration. (2012). Road weather management program: Snow and ice. Retrieved from http://ops.fhwa.dot.gov/weather/weather_events/snow_ice.htm

14.

U.S. Energy Information Administration. (2013). U.S. on-highway diesel fuel prices. Retrieved from http://www.eia.gov/petroleum/gasdiesel/

15.

U.S. Geological Survey. (2013). How much water does the average person use at home during the day? The USGS water science school. Retrieved from http://ga.water.usgs.gov/edu/qa-home-percapita.html

16.

Veneziano

Shi

Ballard

(2010). Development of a toolkit for cost-benefit analysis of specific winter maintenance practices, equipment, and operations: User manual. Retrieved from http://www.clearroads.org/research-projects/downloads/09-08cost-benefitanalysis%20Manual_Final.pdf