New Orleans Soil Lead (Pb) Cleanup Using Mississippi River Alluvium:  Need, Feasibility, and Cost

Abstract

In New Orleans, LA prior to hurricane Katrina 20-30% of inner-city children had elevated blood Pb levels > or =10 microg/ dL and 10 census tracts had a median surface soil level of Pb >1000 mg/kg (2.5 times the U.S. standard). This project tests the feasibility of transporting and grading contaminated properties (n = 25) with 15 cm (6 in.) of clean Mississippi River alluvium from the Bonnet Carré Spillway (BCS) (median soil Pb content 4.7 mg/kg; range 1.7-22.8). The initial median surface soil Pb was 1051 mg/kg (maximum 19 627). After 680 metric tons (750 tons) of clean soil cover was emplaced on 6424 m2 (69 153 ft2), the median surface soil Pb decreased to 6 mg/kg (range 3-18). Interior entrance wipe samples were collected at 10 homes before and after soil treatment and showed a decreasing trend of Pb (p value = 0.048) from a median of 52 microg/ft2 to a median of 36 microg/ft2 (25th and 75th percentiles are 22 and 142 microg/ft2 and 12 and 61 microg/ft2, respectively). Average direct costs for properties with homes were $3,377 ($1.95 per square foot), with a range of $1,910-7,020, vs $2,622 ($0.61 per square foot), with a range of $2,400-3,040 for vacant lots. Approximately 40% (86,000) of properties in New Orleans are in areas of >400 mg Pb/kg soil and estimated direct costs for treatment are between $225.5 and $290.4 million. Annual costs of Pb poisoning in New Orleans are estimated at approximately $76 million in health, education, and societal harm. Urban accumulation of Pb is an international problem; for example, the new Government of Norway established a policy precedence for an isolated soil cleanup program at daycare centers, school playgrounds, and parks to protect children. New Orleans requires a community-wide soil cleanup program because of the extent and quantity of accumulated soil Pb. The post-Katrina benefits of reducing soil Pb are expected to outweigh the foreseeable costs of Pb poisoning to children returning to New Orleans.

Geochemical legacies and the future health of cities: A tale of two neurotoxins in urban soils

“…Zahran et al (2010) report on how natural processes did this same experiment, seeing substantially lower blood Pb levels for New Orleans children after Hurricane Katrina, due to the capping of much of the Pb-contaminated soil with flood-related sediments. Mielke et al (2006) observed that, over the course of several months after treatment, soil Pb levels in the treated sites began increasing. This increase was due to dust generated from soils from adjacent, untreated yards and neighborhoods that still had high soil Pb concentrations.…”

“…Most mitigation efforts for heavily-contaminated soils have involved soil removal and replacement, a disruptive and expensive option for controlling Pb sources in urban areas. Another approach was tested which was simply to cover the contaminated yard soils with about 15 cm of Pb-free soil, which in the case of New Orleans came from the nearby Mississippi levee (Mielke et al, 2006). At a fraction of the soil removal cost, this clean soil is simply graded over the old soil layer, hydroseeded, and left to grow a lawn.…”

“…This approach caps the Pb-contaminated soils, removing them from contact by children. The result of this approach has been a substantial reduction in the blood Pb levels of children living in the affected homes (Mielke et al, 2006). Zahran et al (2010) report on how natural processes did this same experiment, seeing substantially lower blood Pb levels for New Orleans children after Hurricane Katrina, due to the capping of much of the Pb-contaminated soil with flood-related sediments.…”

“…As indicated above, surface capping of Pb-contaminated soils is effective, especially if done on a neighborhood rather than individual property scale. Mielke et al (2006) calculated that the entire Pb-affected area of New Orleans could be remediated by capping for a total cost of less than $US 300M, compared to the $76M annual cost to New Orleans of Pb poisoning. Simply put, the national cost of doing nothing about soil Pb is staggering- Gould (2009) calculates that Pb poisoning costs the nation $US 30-146M in special education, $US 267M in attention deficit-hyperactivity disorder, and $US 1.7B in the direct cost of crime and recidivism.…”

Biogeochemical characterization of municipal compost to support urban agriculture and limit childhood lead exposure from resuspended urban soils

“…Capping lead contaminated urban soil with clean fill prevents contaminated soil from being resuspended as dust, thus reducing exposure through ingestion and inhalation of this resuspended soil dust, especially in summer months (Beniston and Lal, 2012;Filipelli and Laidlaw, 2010;Mielke et al, 2006;Mielke et al, 2011;Mielke et al, 2013;Wortman and Lovell, 2013). This approach is effective and financially feasible when a readily available, locally sourced fill is applied to exposed soils at the neighborhood scale (Filippelli et al, 2015).…”