The Memphis Aquifer Needs Protection and Management
Written by Deborah Baker Carington
As a scientist who has studied groundwater aquifers and the complex of laws and regulations that keep an aquifer healthy for years, I understand the very real risks an oil pipeline spill would pose to the region’s most precious resource, the Memphis aquifer.
A recurring argument from lawyers and PR folks of Plains Pipeline is that they already have state and federal permission to build it. But those permits cover “surface intrusions” only “involving very shallow trenching and boring techniques for which we have no reason to believe there is any possibility of affecting the deep regional aquifer.”
So says the state. So say the feds. Gravity and common sense say something quite different.
I attended all three Byhalia Connection Open Houses in January 2020. The Plains’ pipeline team admitted: there was no risk assessment of the aquifer because it was not required for the permits. They argued there was no basis for a study of harm to the Memphis aquifer because the proposed pipeline was just 4 feet below the surface. The reality of what happens below ground is more complicated. As a rule of thumb—what happens on the surface does not stay on the surface.
Memphis sits over a deep, bathtub-like area of the aquifer
The aquifer system has many layers—the shallow aquifer, the protective clay layer and the deep Memphis aquifer (also known as the Memphis Sand Aquifer and the Sparta in Mississippi). The groundwater in the deep aquifer is thought to be protected by the clay layer above it, but natural gaps or breaches in the clay allow surface water and pollution to seep into the Memphis aquifer. Shelby County is dotted with examples of surface pollution on the move—downward.
Blue: The plumes beneath Poplar Avenue in Collierville
In Collierville, TDEC and the EPA still watch the plumes below Poplar Avenue, part of the ongoing remediation work there for the last 30 years. Here, the Carrier and the old Smalley-Piper Plants are adjacent Superfund Sites that have contaminated the groundwater with trichloroethylene (TCE) and hexavalent chromium (CH6). In 2004, the presence of the chemicals forced the shutdown of a municipal water plant. The TCE and CH6 originated in the soil and surface water runoff.
As one of the partners in the pipeline, Valero knows all about surface contamination seeping into groundwater at its site in south Memphis. A plume of hydrocarbon pollution moves in the shallow aquifer beneath the Valero Refinery where the proposed pipeline will originate. Hydrocarbons were reported in the groundwater as early as 1984 and ongoing remediation started under TDEC in 1998. The contamination originated from waste oil and leaks at the surface.
In addition to ignoring the pathway for surface pollution to reach our drinking water, Plains ignored sensitive zones (as did the state permit). The proposed pipeline plows through geologically critical zones along the route. The Memphis portion of the pipeline crosses an MLGW Wellhead Protection Zone.
Map of the Pipeline Route through the Davis Well Field
The route goes right through the Davis Well Field in southwest Memphis between and near two drinking water wells. Alarmingly, the Davis Well Field is near known and suspected breaches in the clay layer. That’s an oil pipeline running over gaps in the clay layer and next to wells that pump city water to residents of Boxtown and industries on President’s Island.
In north Mississippi, the last quarter of the pipeline route crosses the aquifer Recharge Zone where the aquifer sand formation reaches the surface. Here rainfall and surface water replenish the aquifer. Here the protective clay layer is absent, so any pollution at the surface goes directly into the groundwater. (See first photo: “Recharge Zone” on the "Memphis Aquifer” cross-section.)
All of these risks are multiplied by the location of Memphis in the New Madrid Seismic Zone, with a seismic hazard risk as high as California. Seismologists, engineers and public officials regarded the seismic risk serious enough in 2000 to retrofit the Mississippi River I-40 Bridge to withstand a magnitude 7.5 earthquake—at the cost of $275 million. To date, Plains has not publicly discussed seismic safety standards. The reason they gave was familiar: no report on seismic hazards (or safety protocols for the public) was required for the permits.
New Madrid Zone with California comparison
It is fitting and proper for local leaders and all water users to consider the risk of this pipeline. Given the crazy regulatory gap that our aquifer falls into—no study, no new research along the route, not one permit to address groundwater, and no discussion of critical zones—Memphis should consider an “aquifer authority” to take charge of managing and protecting the aquifer. Protection goes beyond just one pipeline or just one industry, and leaders should consider the value that the aquifer adds to our corner of Tennessee.
In our homes, we appreciate that value every day. Industry also understands the value of the aquifer. Consider the impact of doing business without plentiful clean water.
Imagine the cost to adopt alternative sources or to create expensive water treatment facilities. At the same time, laws must strike a balance between regulation and development, with the singular aim of protecting our irreplaceable water resource. In so doing, the Memphis aquifer will remain sustainable and viable as a foundational element of our economy for the next generation.
Written by Deborah Baker Carington
Deborah Baker Carington is a career geologist who sits on two Boards that regulate and protect two different aquifers: the Edwards Aquifer Authority in San Antonio and Protect Our Aquifer here in Memphis. She has a BS in Geology from University of Southern Mississippi and MS in Geology from University of Memphis.