Common Ground Alliance, http://call811.com/before-you-dig/risk-reduction

Stacy Cummings, “Do You Know What’s Below? Call 811 Before You Dig!”, U.S. Department of Transportation “Fast Lane” blog, Aug. 6, 2015, https://content.govdelivery.com/accounts/USDOT/ bulletins/1132ec1

National Transportation Safety Board, pipeline accident brief, http://www.ntsb.gov/investigations/AccidentReports/Reports/PAB1302.pdf

Washington State Department of Labor & Industries,http://www.lni.wa. gov/safety/research/face/files/711362015laborerelectrocuted.pdf

Cynthia Quarterman, “An Easy Call to 811 Could Prevent a Call to 911,” U.S.Department of Transportation “Fsne” blog, https://www.transportation.gov

Common Ground Alliance, 2017 DIRT Report

U.S. Department of Transportation, Pipeline and Hazardous Materials Safety Administration, “Safe Digging Testimonial: A Call to 811 Could Prevent a Call to 911,”April 21, 2014, https://www.youtube.com/watch?v=_VaT0g-76bI#t=21

OSHA “Trenching and Excavation” Web page,https://www.osha.gov/ SLTC/trenchingexcavation/

OSHA, “Trenching and Excavation Safety” guide, 2015, https://www. osha.gov/Publications/osha2226.pdf

U.S. Bureau of Labor Statistics, “Nonfatal Occupational Injuries and Illnesses Requiring Days Away from Work, 2014,” http://www.bls.gov/news.release/pdf/osh2.pdf