1. 7.2.1 Site Remediation (i.e. Cleanup)
      2. 7.2.2 Site Redevelopment
      3. 7.3 Highways and Roads

Pennsylvania Stormwater Best Management Practices Manual
Chapter 7
Brownfield sites have a wide range of complexity, primarily dependent on previous, existing and
proposed land use. Land development at brownfield sites normally occurs in two stages: (1) site
remediation and (2) redevelopment. Planning, design and construction work associated with
these two stages typically involve separate consultants and/or contractors. There are very few
practitioners who perform both stages of work. This bifurcation of responsibility can potentially
lead to miscommunication, mistakes and problems. It is critical that both parties coordinate and
are mutually agreeable to the proposed activities at the site.
When applying for permits for a brownfield site (for either stage), it is imperative that the applicant
provide full disclosure, including but not limited to the following information:
1. Existing and previous land uses
2. Potential pollutants, along with a summary of sampling data.
3. Source and location of the potential pollutant(s) on the Erosion and Sediment Control
(E&S) Plan drawings,
4. A description of what measures are proposed to manage and control discharges of these
pollutants to eliminate the potential for pollution to surface waters of the Commonwealth.
7.2.1 Site Remediation (i.e. Cleanup)
The site remediation stage does not typically generate new impervious surfaces. In fact,
remediation may reduce impervious area through the demolition of buildings and other
impermeable surfaces. These areas, along with other earthmoving related to the cleanup, are
usually temporarily stabilized until the site is redeveloped. As a result, this stage of land recycling
does not typically require structural infiltration stormwater BMPs. The focus of site remediation
routinely involves earthmoving to address soil and groundwater contamination. The stormwater
management portion of this work is normally limited to non-structural BMPs, consisting of detailed
construction sequencing or other measures to prevent the transport of contaminated runoff from
the site.
How stormwater is managed on brownfield sites depends largely on how the site was remediated.
Contaminated soil can be completely removed from the site, contaminated soil can be isolated
and capped, or contaminated soil can be blended with clean soil so that it meets state standards
for public health and safety. For more information on site remediation, go to:
www.depweb.state.pa.us.
7.2.2 Site Redevelopment
Most of the site improvements occur in the redevelopment stage. It is imperative that this stage
of the project does not disturb any completed work from the site remediation stage (e.g. a cap or
other cleanup remedy). Conflicts most frequently arise during the foundation work or utility work
phases of a project. Utility lines, in particular, are often overlooked and can have a major impact
by opening new preferential pathways for contaminants to migrate. Each stage should be
considered independently; ideally, the remediation work should be completed prior to
commencing redevelopment work.
The redevelopment stage is where any net increase of impervious area would be expected to
occur; thereby leading to increases in the rate and volume of stormwater runoff. Even where
there is no net increase in impervious area, the existing site is usually devoid of any notable
stormwater management BMPs. This is the stage where post-construction stormwater
management must be addressed.
363-0300-002 / December 30,
2006
Page 2 of 28

Pennsylvania Stormwater Best Management Practices Manual
Chapter 7
All stormwater management options are available for use on brownfield sites where the
contaminated soil has been completely removed from the site. Emphasis should be placed on
minimizing the amount of earth disturbance area and soil compaction, minimizing the creation of
impervious area, maximizing stormwater infiltration, and dispersing runoff to a number of BMPs
scattered around the site rather than conveying and concentrating runoff to just a few locations.
For the less severe cases, a brownfield redevelopment can follow the same track as a
conventional land development project, provided that certain precautions are taken. To facilitate
this process, the applicant should clearly identify on their plan drawings where “hot spot” areas
are known to exist and any associated remediation that may have occurred. The project
consultants should prepare this vital information during the site remediation stage. Except for
structural stormwater infiltration BMPs, the stormwater management options listed in this manual
are also available for use on brownfield sites where contaminated soil is isolated and sealed, or
the contaminated soil was blended with clean soil. Since soil contaminants are still present at
these sites, the use of structural
stormwater infiltration BMPs should be used only if the residual
soil contaminants are non-soluble
pollutants.
Precipitation and some runoff can be infiltrated through lawn and landscaped areas. These areas
should be designed to have a layer of topsoil at least 8 inches thick. The topsoil should contain
sufficient decomposed organic material (10 percent by dry weight is recommended in the
Stormwater Management Manual for Western Washington) to provide cation exchange capacity
to remove pollutants.
Bio-retention
provides good options for water quality BMPs on all sites, including brownfield
sites. Bio-retention coupled with infiltration should be considered on brownfield sites where all soil
contaminants have been removed during remediation, or where only non-soluble
contaminants
remain. On brownfields where soluble contaminants
are still present in the soil, bio-retention
BMPs should be designed so that all water passing through the planting soil is directed to an
overflow and not permitted to infiltrate.
Vegetated roofs
can be used effectively on brownfield sites to retain much of the rainwater that
falls on the roof. This BMP is very effective in areas where subsurface systems are not feasible.
Stormwater can also be retained in basins or landscaped ponds and allowed to evaporate.
Cisterns
and vertical storage units can be placed in corners of structured parking lots, inside
buildings, on the outside walls of buildings, in adjacent alleys, alongside elevator shafts, and
other locations deemed feasible by the designer. Vertical storage is particularly applicable to
urban areas where space is at a premium. The shape and location of this BMP requires very little
land area. Water collected this way can be re-used for things such as fire suppression, drip
irrigation, lawn sprinkling, cooling buildings, toilet flushing and recreational water.
Chapter 6 of this manual provides more detailed information on these structural BMPs.
7.3
Highways and Roads
The purpose of this section is to consider the most suitable BMPs for managing runoff from
roadways. Consideration of roadway design, construction, and maintenance should be included
in the selection of BMPs that minimize the rate and volume, and enhance the quality of roadway
runoff.
363-0300-002 / December 30,
2006
Page 3 of 28

Back to top