Soil & Lead How can risk from exposure to lead in residential soils be reduced to tolerable levels?
What's the Problem?                    

Even though many chemical contaminants may be present in the city's residential soil, lead appears to present the highest risk, and  has been the most studied.  Lead poisoning is one of the greatest public health hazards that faces City residents.  Providence children have elevated blood lead levels at a rate eight times greater than the national average.  Although the primary source of concern for childhood lead poisoning is within housing units, lead in soil is also a factor and efforts to assess and reduce the amount of lead in soil have been part of the goal  to reduce risks of lead poisoning.

There are many activities that can cause lead to accumulate in soils.  Some of these activities may have happened in the past, and no longer add to a site's soil lead contamination.  For example, leaded gasoline is no longer used, but residues from its emissions remain in soils near roads. Lead may have also been added to soil from point sources, such as burned trash, metal smelters, jewelry plating operations, or dumped lead batteries. 

The largest source of lead in residential soil is lead-based paint, used widely before being banned in 1978.

 

                                                 

                                         

Thinking about Soil Lead for Two Different Types of Property:               Vacant Lots & Housing Properties

When dealing with soil lead contamination for residentially zoned properties, it is important to separate vacant lots

from housing properties.  Here are three questions about soil lead that have different answers, depending on

whether you are thinking about vacant lots or housing properties:

  1. What areas are of most concern?

  2. What facts have we gathered?

  3. What do the facts tell us about the level of risk?

 

VACANT LOTS

1.  What Areas are of Most Concern?

Most vacant lots used to have buildings on them.  Over the years, the buildings either burned or were demolished.  Lead paint from structures that once stood on vacant lots is the primary source of soil lead.  In order to locate areas of highly concentrated soil lead, called hotspots, soil testing is needed.  Many samples are taken from organized locations on the lot.  The individual samples can find hotspots.  If all of the samples are averaged, then  you can figure an average concentration for the number of parts per million (ppm) of lead in the soil.  In order to find the areas of most concern, this type of soil testing is needed.

 

2.  What Facts Have We Gathered?

With the help of EPA's Region 1 Urban Environmental Initiative 67 of the city's vacant lots have been tested for lead soil contamination.  The following are categories of average concentrations of soil lead from this study.  For example, (looking from the left column to the right) the chart shows that 7 of the lots had average concentrations above 1,000 ppm.  This means that those 7 lots fall into the Significant Environmental Lead Hazard Standard: 

Number of Lots

Average Concentration in Parts Per Million (ppm)

Level of Risk

4

below 150

Lead-Free Standard

36

between 150-500

Lead-Safe Standard

20

between 500-1,000

Lead-Safe Standard

7

above 1,000, but below 10,000

Significant Environmental Lead Hazard Standard

 

Using Soil Standards:  What is a Safe Level of Soil Lead?

Most vacant lots used to have buildings on them.  Over the years, the buildings either burned or were demolished.  Lead paint from structures that once stood on vacant lots is the primary source of soil lead.  In order to locate areas of highly concentrated soil lead, called hotspots, soil testing is needed.  Many samples are taken from organized locations on the lot.  The individual samples can find hotspots. If all of the samples are averaged, then  you can figure an average concentration for the number of parts per million (ppm) of lead in the soil.  In order to find the areas of most concern, this type of soil testing is needed.

 

3.  What Do the Facts Tell Us About the Level of Risk?                        
0-150 ppm
The four lots with average concentrations below 150 ppm fall into the Lead-Free Standard category, and do not pose a risk to people, or require any remediation measures.

150-500 ppm
The 36 lots with average concentrations between 150-500 ppm are considered Lead-Safe, and are safe for older children and adults. If small children who eat more dirt than others or absorb lead easily use these properties, efforts to make such lots Lead-Free are suggested. With nearly half of the lots in this category, the study suggests that many of the city's lots require fairly simple and relatively low cost measures for lead soil risk reduction.

500-1,000 ppm
The 20 lots with average concentrations between 500-1,000 ppm require efforts to keep the contaminated soil covered. Here is a list of ways the RI DOH suggests to cover soil: 4 inches of gravel, 6 inches of mulch, 3 inches of lead-free soil, or new grass.

1,000-10,000 ppm
The 7 lots with average concentrations above 1,000 ppm pose a Significant Environmental Lead Hazard. Here are four ways the RI DOH suggests to manage this hazard:

  1. Tilling with damp lead-free soil to reduce the concentration of lead in the soil to less than 1,000 followed by covering the soil by any of the methods mentioned above.
  2. Covering the soil with concrete, asphalt or any other permanent cover approved in writing by the RI DOH
  3. Soil removal and disposal
  4. A site-specific remediation plan which has been approved in writing by the RI DOH

With roughly 10% of the total lots in this category, this study suggests that only a relatively small number of the city's lots pose a significant environmental hazard, and require remediation that is both expensive and complex.

Above 10,000 ppm
If soil concentrations are higher than 10,000 ppm, excavation is required by RI DOH regulations, unless a variance is obtained.

HOUSING PROPERTIES

1.  What Areas Are of Most Concern?

Housing properties have more clearly defined areas of concern than do vacant lots.  Because the primary source of soil lead comes directly from exterior lead-based house paint, the highest concentrations are usually found near the exterior walls of houses.  This area is called the drip-zone, and it is defined as a six foot zone around your home.  This makes the drip-zone a prime area of concern.  But the lead doesn't necessarily stay only in the drip-zone.  Any disturbance of soil can cause the lead to spread into your yard.  Wind, rainwater, sprinklers, and anything that kicks up bare dirt--like  a child running along a worn path near the house--can all spread lead into your yard.  Places with  bare soil and heavy traffic allow for exposure of soil lead.  This makes places with  bare soil and heavy traffic other areas of most concern.

2.  What Facts Have We Gathered?

An analysis of RI DOH soil lead data was recently completed by a graduate student at Brown University.  This study found that of the 280 housing properties tested, 190 would be classified as Significant Environmental Lead Hazards, and would require one of the four options mentioned by the RI DOH for remediation.

3.  What Do the Facts Tell Us About the Level of Risk?

This study suggests that nearly 70% of housing properties require significant lead management efforts, according to the RI DOH lead standard regulations.  The level of risk appears to be much higher for housing properties than vacant lots.

VACANT LOTS & HOUSING PROPERTIES

Why is Soil Lead Management So Difficult?                                          

Unlike commercial and industrial sites that qualify for remediation funding under classification as Brownfield sites, residentially zoned properties are currently not eligible for federal funding.  From taking the first step of testing soil to eventually remediating contaminants, private owners must absorb the cost of all management efforts.  This poses a significant problem for the majority of Providence's contaminated residential properties, many of which are owned by low income or absentee owners.  Many of these properties, especially vacant lots, have significant back debt--overdue taxes, boarding & demo liens, etc.  These costs often exceed the value of the land.  Cleanup costs add to this financial burden.  Grants are one option for funding residential cleanups because loans do not have equity. 

Recent price quotes for site remediation at four highly lead contaminated vacant lots in Providence ranged from $3,700 to $6,400. These quotes included labor, equipment, materials and disposal of waste. Similarly, a project in Boston found that the average cost of soil removal for hazardous properties ranges between $5,000-$10,000 dollars. The cost for removal of lead contaminated soil in RI is usually cheaper because of Rhode Island's Household Hazardous Waste Exception, stating that lead waste that is generated from residentially zoned property may be treated as household, vs. hazardous, waste.  Property owners need to be aware of low cost management options for soil management. The cost of managing soil contamination, along with the planning necessary for effective abatement, pose two significant obstacles for residential soil remediation.

 

What Might Help the Problem?

  1. Compile comprehensive database of all certified lead soil tests for residential properties, including major study results and individual site testing results.
  2. Conduct soil tests to detect a wider spectrum of chemical contaminants.
  3. Provide grants to qualified residents to mitigate risks on lead contaminated vacant lots.
  4. Allocate municipal funds to purchase large quantities of compost and other soil remediation materials that can then be sold to residents at uniform low price.

Resources & Contacts

  • Rhode Island Department of Environmental Management: Kelly Owens, Department of Waste Management. Phone: 222-2797
  • Rhode Island Department of Health: Robert Vanderslice, Environmental Health Risk Assessment. Phone: 222-4948
  • Environmental Protection Agency, Region I: Kristi Rea, Urban Environmental Initiative. Phone: (617) 918-1595

Regulations/Legislation:

  • "Rules and Regulations for Lead Poisoning Prevention" [R 23-24.6-PB]. February 1992. RI DOH.
  • "Rules and Regulations for the Investigation and Remediation of Hazardous Material Releases" [DEM-DSR-01-93]. March 1993. RI DEM.
  • "Lead Paint Contamination Debris Disposal Guidelines" RI DEM.