Page 39 - Green Builder March-April 2016 Issue

CREDIT: USDA 7 STEPS TO
Alternatives. In some cases, you may decide to avoid the problem
of existing soils by choosing stormwater features that don’t rely on
infiltration, such as green roofs, and by incorporating raised beds
or vertical gardens.
take advantage of public records available at county offices, planning
departments and historical societies. In general, lots that were
previously used for housing are less likely to have soil contaminants
than those used for industrial purposes.
Conduct a field survey. Observe drainage patterns, identify
foundations of previous structures and look for evidence of
compaction.
Sample the soil. At a minimum, the soil test should include pH,
percent organic matter, nutrients, micronutrients and metals,
including lead. Soil samples can be sent to USDA Cooperative
Extension System offices, land grant universities or private local
laboratories.
In 2013, EPA released Implementing Stormwater Infiltration
Practices at Vacant Parcels and Brownfield Sites (http://bit.
ly/1RqP0aV). This document guides decision-makers through
a series of questions to determine whether infiltration or other
Lead Removal Best Practices
1. Remove soils and replace.
2. Add clean soil on top of the lead-contaminated soil.
3. Maintain soil pH levels above 6.5 by adding organic
matter. Lead binds to organic matter, making it less
available to plants.
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HEALTHIER
SOILS
WORKING IN COMPOST can improve drainage
or moisture retention, encourage biological
activity and grow healthier plants. A good rule
of thumb is to add two inches of compost over
the entire area and work it in to a minimum depth of six
inches, adjusting this depth to accommodate tree roots and
other obstacles.
Here’s a simple formula for estimating the volume needed:
ONE INCH COMPOST SPREAD OVER
1,000 SQUARE FEET = THREE CUBIC YARDS.
Here are some general guidelines for application:
1. Rototill to a depth of six to eight inches. If the soil is too
dense for a rototiller, the soil should first be broken up into
large aggregates using a soil ripper.
2. Clear obstructions. The soil surface should be reasonably
free of large clods, roots and stones greater than two inches.
3. Distribute compost evenly to a depth of two inches over
the soil surface. For small areas, compost may be spread
by hand with a shovel and raked evenly over the soil. For
larger areas, use a tractor-mounted spreader or similar
device.
4. Spread lime and nutrients, if indicated by soil testing.
5. Rototill several times in perpendicular directions to
incorporate compost and other soil amendments.
6. Water thoroughly. Allow soil to settle for one week; if
compost is immature, extend settling period to two to
five weeks.
7. Finely grade soil to desired evenness.
stormwater management approaches are appropriate for a specific
brownfield property.
4. SEDIMENT-LADEN STORMWATER
In arid regions, bare soils are common and rates of erosion and
sedimentation are relatively high. Stormwater flows can deliver
fine sediments to infiltration features, clogging and degrading
their performance. The following strategies are recommended for
infrastructure in areas with high sediment loads.
Mulch it. Mulch acts as a filter for sediments carried in stormwater.
Add a mulch layer above infiltration practices and replace the layer
when it is filled to protect the soil and gravel layers below from
sedimentation.
March/April 2016 GREEN BUILDER 37