pumping groundwater out,” these of the water table in coastal areas where For related articles: “ghost saltwater wetlands,” as Hill calls the cities built on sand are at risk. www.erosioncontrol.com them, are only too eager to return to “When we put our pipes in we their natural conditions. counted on the water table being low; we “They’re all coming back, even the freshwater ones, channelized rivers, we tried to move it and drain it out and we’re seeing filled pipes, non-functioning sewer systems, of the ‘sponge.’ So we made open voids of concrete-lined and flooding.” channels and pipes, but now that sea water is rising, it’s And ironically, in a perverse turn of events, the infiltra-pushing up groundwater, and those pipes can get filled and tion of unwanted legacy contaminants “that we so efficiently sewers can back up.” did all that work on to cap from above so rainwater wouldn’t What happens in this case is even though the stormwater mobilize those solids, are now migrating from below.” pipes “appear to be functioning they aren’t because they are She continues, saying, “These [sites are] capped but not 90% full.” lined, so they can remobilize into our water supply,” creating yet another unanticipated effect of groundwater. All of these How Waters Compete issues make the freshwater flooding “a complicated three-Groundwater is a saturated zone of soil—if there’s rain dimensional problem that we just have to get started on. the level goes up, if not, it goes down but in areas of high “Our stormwater pipes are reducing the groundwater infiltration rate, “like sand, it’s locally higher, when it [water] level; it’s lower where there are pipes installed, then it gets subsides, goes down quickly. in the pipes, and as those fill, the groundwater rises around “Now picture this, in low-lying areas we’re focused on the shoreline as the areas that are affected by flooding. But in those pipes.” rising sea levels, the flooding area is twice as large when you add in the freshwater groundwater flooding.” And in some Utilities Can Springboard Solutions Hill says groundwater is the most important piece of this regions, land is sinking as well. coastal drama, but there are strategies to tackle these chaotic “In areas of subsiding landmass, Norfolk, Virginia, for example, there’s a rising water table because there’s rising sea hydrological curve balls Mother Nature is throwing at us. She advises use of 3D maps that illustrate more than just level; these are areas that are literally sinking.” a projected rise in sea level, but are the true picture of the In Oakland, CA, which Hill says is “a city largely built dynamics of groundwater, rising water table, sinking land-on sand and an arm of an estuary, and they are constantly Register today @ ForesterUniversity.net! New Webinar! FORESTER UNIVERSITY PRESENTS Evaluating Erosion, Sediment, & Sedimentation in Roadway Projects Wednesday, Nov. 9 th Keep your roadside dirt where it belongs! Join Jerald Fiﬁeld, Ph.D., PH, CPESC, CISEC and Tina Evans, PE, CISEC, CPESC to explore the differences between erosion, sediment, and sedimentation, as well as develop an understanding of these variables allowing for the quantiﬁcation of erosion and sediment yield on a roadway project site. Earn 1 PDH / 0.1 CEU! Speakers: Jerald Fiﬁeld, Ph.D., CISEC, CPESC HydroDynamics Inc. Tina Evans, PE, CISEC, CPESC HydroDynamics Inc. BRINGING YOU CUTTING-EDGE TECHNOLOGY AND TOOLS–ANYTIME, ANYWHERE Follow us @ ForesterU Like us @ Forester.University Subscribe @ ForesterUniversity Add us @ Forester.University 42 EROSION CONTROL WWW.EROSIONCONTROL.COM FU_EC1611_evalErosionRdwts_5p Register today @ ForesterUniversity.net!