Generally, the city owned mainline sanitary sewer is installed very deep in the ground compared to the depth a gas pipe is installed. The previous thinking in the natural gas industry was the elevation difference was so great that there was a very low risk of damaging a sanitary sewer or sewer lateral. However, many sanitary sewers were installed years ago when standards were not as strict as they are today. Likewise, the standards for installing sewer laterals were not as stringent. Therefore, there are instances when the elevation difference is not nearly as great as what it would be by today’s standards.