No 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.

A comparative study of two coagulants, aluminum sulfate (Alum) and aluminum chlorohydrate (ACH), used in parallel in a full scale water treatment plant (WTP) in Ohio from October 2009 to December 2012, was conducted to determine disinfection by-product (DBP) formation potential removal based on both dissolved organic matter (DOM) and fluorescence-derived metrics. Water quality parameters and fluorescence intensity of water samples collected before and after coagulation were measured three times per week and fluorescence matrices were analyzed using parallel factor (PARAFAC) analysis, while DBP formation potential was measured in a weekly basis in pre-and post-coagulation water samples. This study revealed that Alum consistently removed more trihalomethane (THM) formation potential per mg/L of dissolved organic carbon (DOC) than ACH. ACH treated waters averaged approximately 33% more THM formation potential when normalized to DOC. Similarly, haloacetic acid (HAA) formation potential averaged 10% higher in ACH treated waters. From the fluorescence analysis, PARAFAC components C1 and C2 (humic-like fluorophores groups) removal were 23% and 16% higher, respectively, with Alum when compared to ACH. Monte Carlo simulations, based on neural network models developed from the field data, were performed to compare DBP formation across a wide range of conditions. At similar pH, the model results showed that ACH coagulated water had 13% and 20% higher THM and HAA formation potential, respectively, when compared with Alum. The observations from this study reveal that a coagulant's preferential removal of DBP precursors has an impact on DBP formation despite similar DOC removal.

The Ohio Department of Transportation has more than 60 facilities without sewer access generating approximately 19 million gallons of winter maintenance wash water. Off-site disposal is costly, creating the need for sustainable management strategies. The objective of this study was to conduct an exploratory feasibility analysis to assess wash water disposal and potential reuse as brine. Based on a comprehensive literature review and relevant environmental chemistry, a sampling protocol consisting of 31 water quality constituents was utilized for monthly sampling at three geographically distinct Ohio Department of Transportation garages during the winter of 2012. Results were compared to local disposal and reuse guidance limits. Three constituents, including a maximum copper concentration of 858 ppb, exceeded disposal limits, and many constituents also failed to meet reuse limits. Some concentrations were orders of magnitude higher than reuse limits and suggest pre-treatment would be necessary if wash water were reused as brine. These water quality results, in conjunction with copper chemical equilibrium modeling, show pH and dissolved carbon both significantly impact the total dissolved copper concentration and should be measured to assess reuse potential. The sampling protocol and specific obstacles highlighted in this paper aid in the future development of sustainable wash water management strategies.

When locating new facilities, departments of transportation must consider how the wash water generated during routine winter operations will be managed. Previous research has shown that two options are likely to be the most cost-effective: (a) collecting and hauling off-site for disposal (C DISPOSE ) or (b) connecting to an existing sanitary sewer system (C SAN ). In this article, the cost-effectiveness of these two strategies for Ohio Department of Transportation (ODOT) maintenance facilities was evaluated probabilistically using Monte Carlo simulation. The probability C DISPOSE was the most cost-effective option was greater than 90% for existing ODOT facilities without sanitary sewer access if the sanitary sewer capital cost exceeded US$172,000. Considering all ODOT facilities, there was 90% probability C DISPOSE was the most cost-effective option if the sanitary sewer capital cost exceeded US$280,000. These results can be used to guide facilities management decisions regarding wash water management options for both existing and future facilities.