Launch Slideshow

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By the book

By the book

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    Contractors tunneling under a roadway: These workers are operating under a contractor-provided health and safety plan. Appropriate personal protection equipment and forced-air ventilation of the excavation tunnel was specified in the contract. Photos: City of Dallas

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    Proper stockpiling of contaminated soil: Note the proper stormwater fencing at this Dallas Water Utilities project; stockpiled soils are located on and covered with plastic.

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    The below map is an example of a Dallas Water Utilities GIS search showing locations of regulated facilities with the potential for contaminant releases that could impact the utility's rights of way. Blue circles: city-permitted monitoring wells. Green diamonds: Voluntary Cleanup Program sites. Red diamonds: Leaking Petroleum Storage Tank Program sites. Orange shields: registered dry cleaners. Map: City of Dallas requires developers

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    A probable unacceptable condition: The surrounding natural color of soil in this soil column is contrasted by the dark, stained affected soil.

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    Unacceptable condition: Nonaqueous phase liquid (NAPL, or free-phase product) is present on the surface water at the bottom of a utility excavation. Free-flowing fuel, obviously discolored groundwater with a rainbow “sheen,” and strong odors exist at this project.

By John Sallman, PG

OVERVIEW:

WHAT: Soil and Ground Maintenance Plan
OWNER: Dallas Water Utilities
CONSULTANT: Terracon Consultants Inc.
COST: $25,000
TIMELINE: July — November 2011

As cities expand their water distribution territories and redevelop existing areas, water utility infrastructure upgrades become a constant need. Often, upgrades occur along corridors adjacent to commercial and industrial areas that have been impacted by petroleum hydrocarbon and other chemical releases, which pose problems to the integrity of the water utility, the safety of consumers, and the safety of the construction workers installing the utilities.

In Dallas, a large amount of aging infrastructure is slated for replacement and/or upgrades over the next several years. But already, Dallas Water Utilities (DWU) is experiencing major delays and cost overruns on projects due to contamination issues being discovered after construction begins.

Although the utility had management procedures in place, they were reactive instead of proactive, says Chad Kopecki, DWU interim program manager. Plus, the procedures weren't very thorough, consisting of a half-page document of directions on how to react to a contamination situation.

To minimize potential contamination problems before projects begin, the utilities department worked with the Dallas Sustainable Development and Construction Department to institute new requirements for installation and upgrades of water utilities.

Additionally, the utilities department created a manual that establishes mandatory yet easy-to-follow procedures; describes appropriate actions to be taken by staff; provides a much higher degree of liability protection not only to utility customers, but also to contractors; and gives the city and the departments an excellent public image — as public agencies in the mode of continual improvement and innovation.

Interdepartmental synergy

Prior to a few years ago, the water utilities and sustainable development departments largely ignored potential contagion issues and only dealt with upgrading piping, etc., if contamination was discovered during development or construction. Although they have always worked together, they had to step up their collaboration efforts to develop a two-fold strategy that identifies and addresses contaminated properties.

Because each of the two departments caters to its own unique customer base — Sustainable Development customers are property developers while the utility serves water consumers — each took a different approach that complements the other's. Sustainable Development and Construction primarily deals with permitting and code issues on new development and redevelopment of individual properties within city limits. The department established a policy that seeking construction permits to submit information regarding the site's environmental conditions. If the submitted information indicates site soils or groundwater have been contaminated or may be contaminated, the developer is required to conduct soil and/or groundwater sampling to ensure soils and groundwater in the vicinity of the water service lines (i.e., the connection from the water main to the site building) are not impacted.

If contaminated soils or groundwater are identified, the water utility then steps in to require installation of alternate piping, trench construction, or special gaskets for the water service line connecting the site building(s) to the water main, thereby preventing any potential contamination of the water supply to the building(s) and protecting water consumers across the distribution network. It is also important to ensure the trench does not become a pathway of travel for contaminants from one location to another.