Reducing flood risk for NOLA: a tale of two minerals
Editor’s note: The previous two posts discussed the concept of using industrial waste stockpiles as sediment sources to bolster levees in the NOLA area. I had not intended to continue this series but a timely email message from Dallas changed my mind. I was contacted by Lisa Marie Price with the Environmental Protection Agency (EPA) Region 6, who has been pursuing this concept for several years.
I initially proposed considering the feasibility and safety of using two specific industrial waste stockpiles as potential sediment sources for NOLA levees. These waste streams are: (1) red mud, or spent bauxite from alumina production; and (2) phospho-gypsum waste from the production of phosphate fertilizer.
Both of these waste minerals are stored, presumably perpetually,* in huge, ugly and useless stockpiles at riverside locations in south Louisiana.
My second post on this general subject suggested that testing both waste streams may be too ambitious and that perhaps the focus should be solely on red mud. After learning that EPA has been testing both materials I feel vindicated so now I’m back to my initial proposal.
As I have discussed in the two previous posts, Sheila Grissett recently reported in the Times-Picayune that approximately 30 million cubic yards (6 Superdome equivalents or SDE’s) of materials necessary to bolster flood protection levees will soon be redistributed throughout the NOLA area via heavy duty diesel trucks. During the next two years this would add an estimated 50 million miles of traffic-clogging, road-damaging, air-polluting impacts.
The potential to minimize these impacts and to obtain these materials free of charge would seem worthy of very serious consideration by all interests.
Substituting the need to mine “virgin clay” by using waste materials that are currently available conveniently at barge-accessible sites upriver from where they are needed seems an extremely attractive proposition. On the basis of environmental, energy, and financial grounds this alternative would be far preferable to paying landowners to use their deltaic property as borrow pits, resulting in the creation of large holes in the landscape.
In the following discussion I use the shorthand initials for the two waste streams: (1) RM = “red mud,” spent bauxite or soil from Jamaica from which alumina has been extracted for the production of auminum; and (2) PGW = phospho-gypsum waste, phosphate ore from Florida from which phosphate has been extracted to produce ammonium phosphate fertilizer.
EPA has been exploring a mixture of RW and PGW and early results are quite promising, so my initial proposal to use both waste streams has been vindicated. Here are some of the salient facts that I learned from EPA Region 6:
Q and A from LaCoastPost to EPA re suitability of RM and PGW for levee construction
LCP: How much of each mineral is currently stockpiled and available for levee bolsteriing?
EPA: The Gramercy site, now Noranda Alumina (figure 1) currently has on-plant approximately 120 million cubic yards of RM (24 SDE’s). Just on the Mosaic site (figure 2) there is approximately 20 million cubic yards (4 SDE’s) of PGW. There is currently a total of approximately 60 million cu yards (12 SDE’s) of PGW on the banks of the Mississippi at the various fertilizer manufacturing facilities.
LCP: Because EPA has been considering a mixture of these materials, what ratio of RM and PGW seems optimal for levee construction?
EPA: Based on geotechnical testing, either 100% RM or a mixture at the ratio of 4 parts RM: 1 part PGW seem appropriate.
LCP: How does each mineral fare, with respect to supporting the growth of vegetation?
EPA: RM does fine with a little help from nutrient supplements; PGW supports the growth of grass and other vegetation quite well without supplemental fertilizer.
LCP: What is the position of EPA with respect to the use of these two minerals for levee enhancement in NOLA?
EPA: The agency does not have a position at this time, pending ongoing objective and thorough scientific testing of both materials. If the tests conclude that either one or both materials are suitable and that public safety can be ensured then EPA would support their use, rather than digging more borrow pits.
Federal and state support for the concept of using RM and PGW for NOLA levees
After three years of effort, EPA is showing great interest in the potential for the beneficial use of RM and PGW. On the other hand I am hearing from various credible sources that to date the New Orleans District of the US Army Corps of Engineers has dismissed the subject of substituting industrial waste sediments for expensive high quality clay. I find this attitude curious and unhelpful for many reasons. Meanwhile, the corps continues to face harsh criticism from many quarters, not just with the levee failures that led to Katrina flooding but also to the pace of levee enhancement.
At the state level I am very pleased to report that the Louisiana Office of Coastal Protection and Restoration (OCPR) is expressing serious interest in the subject of using one or both waste streams beneficially. This has been verified by two recent conversations with a high level agency official whose name I won’t mention so as not to jeopardize future progress.
*Or until the approaching gulf inundates them, whichever comes first.