MnDOT has prepared this guidance document to provide its internal procedures and requirements for work performed on MnDOT rights of way, including MnDOT-owned facilities. This document should not be construed as a full description of all regulations pertaining to the subject matter. Contact the Regulated Materials Unit in the MnDOT Office of Environmental Services for additional information or legal requirements.
Considerations and Requirements for Installing Permanent Emulsion (Road Oil) Tanks and Mobile (Patch Blower)
Tank Systems Permanent Emulsion Storage Tanks
Emulsion tank system operations are known for frequent spills and therefore require more attention to both tank containment and product transfer area containment than aboveground tank systems containing other products. The typical capacity of these tanks (over 1320 gallons) also requires compliance with federal tank rules in addition to state rules. Consequently, the Office of Environmental Stewardship (OES) does not promote emulsion tanks at MnDOT facilities. If a District is contemplating installing an emulsion tank, the environmental/compliance issues presented in this document should be given serious consideration prior to purchasing a tank system.
These tank systems must comply not only with state regulations but also the federal spill plan. The federal spill plan imposes more stringent requirements on containment measures and emergency response planning than state regulations not only for the emulsion tank but for all aboveground petroleum stored in containers greater than 55 gallon capacity. Following are some of the requirements imposed by the federal spill plan:
- Tank System: Typical MnDOT emulsion tank installations are single-walled tanks located outdoors.
- Required secondary containment is typically accomplished by constructing an impermeable concrete floor and berm around the tank that will hold 110% of tank volume.
- Rainwater and snowmelt comes in contact with spilled emulsion within the containment area and must be managed correctly. Typically by soaking up product from surface with hydrophobic pads and then discharging water.
- Required documented inspection of single-walled outdoor tanks every week.
- Outdoor containment areas must be inspected every week to ensure that necessary maintenance of the containment area is performed, such as repair of cracked floors or removing of debris.
Recommendation: If these tank systems must be installed at a MnDOT facility, OES highly recommends installing indoor tank systems, such as those at the MnDOT St. Cloud Headquarters. Indoor facilities allow for easier management of product spills, higher probability of compliance with federal and state regulatory requirements and decreased probability of causing environmental harm through product releases. Consult with OES and Building Services on indoor tank installation.
- Substance Transfer Area
- The substance transfer area must contain 100% volume of the largest single compartment of any transfer vehicle that delivers or takes product from the tank. This typically requires a containment area constructed of impermeable material with the capacity to store several thousand gallons of product until actions can be taken to recover the spill.
Recommendation: Careful planning is needed to determine where transfer vehicles will be situated during product transfer operations and where tanker vehicles may park at the facility. Containment is also needed in areas where tankers remain onsite. Consult with OES on transfer area containment.
- Controlled access is required for facilities subject to the federal spill plan.
- This typically requires:
- Fencing with locked gates
- Secured access to tank system and any starter controls
- Lighting system to discourage vandalism and enable spill recovery operations at night.
Additional Recommendation: Security cameras to monitor user operations.
- Properly trained MnDOT staff must be present during product transfers, including delivery by vendors.
- Frequent inspections – weekly for outdoor installations or monthly for indoor installations.
- Annual refresher training required for all personnel who transfer product from tanks.
- Site Plan
- BEFORE the tank system is purchased, plans must be drawn up and submitted to OES for review to make certain that the design will meet federal spill plan requirements and any other internal best practices.
Guidance on Emulsion Tank Cleaning
Mobile (Patch Blower) Tanks
Storage of Mobile Tanks:
- Park tank on curbed, paved surface to contain releases. Ensure that distributer bar and any other tank equipment do not leak product.
Tank Cleaning for Dura Patcher products (look to manufacturer instructions for other brands):
- Use all the emulsion in the tank by using the drain valve on the bottom of the tank.
- Put 3 to 4 gallons of diesel fuel in the tank.
- Close the loading hatch and plug the patcher in with the thermostat set at around 150 degrees and heat overnight.
- Once heated, pull patcher around the yard to agitate the hot fluid in the tank.
- Drain and collect fluid from the tank for disposal/recycling at an approved vendor.
- Check that the tank is clean of any hardened emulsion.
- Once clean, put 3 to 4 gallons of diesel in the tank for long-term storage.
- Prior to using tank system again, heat diesel and drain before loading with fresh emulsion. Collect diesel mix for disposal/recycling at an approved vendor.
Permanent Emulsion Storage Tank
Properly cleaning tanks requires confined space entry and management of tank sludge, therefore, MnDOT personnel should not perform tank cleaning. Contract with one of MnDOT’s approved storage tank recyclers to clean tanks and properly manage tank sludge.