Utilization of Biosolids and other
Residuals for Remediation of
Phytotoxic Materials
W. Lee Daniels
http://www.landrehab.org
Coal Refuse
Disposal Area
Coal Processing Wastes
• Up to 50% of run-of-mine coal from Appalachian
deep mines reports to coal waste disposal piles
• In Virginia alone, we have over 5000 ha of active
and abandoned coal refuse piles.
• The vast majority of Appalachian coal refuse is
potentially acidic with an average lime
requirement of > 10 tons per 1000 (= tons of lime
requirement per acre per 6”).
Complex sulfate
salts and AMD
Coal waste
The vast majority of coal refuse fills in
the Appalachians are net acid forming
and generate AMD which is treated
with chemicals and passive systems.
Challenging Properties
• Inherent Variability. As Barry Stewart once
said: Lee, this stuff is just consistently variable!
• Steep slopes and black color combine to
generate severe heat loads, especially on Sfacing slopes.
• Potential acidity and AMD generation.
Challenging Properties
• Low fertility and P-fixation potentials
from rapidly forming Fe and Al oxides.
• Very low water holding and common
compaction combine to limit rooting
depth.
• Processing surfactants may actually make
the surface hydrophobic, and fills are
compacted for fill stability and to exclude
oxygen to limit combustion.
Three year-old
seeding on acid
forming refuse in
West Virginia
failing due to
excess salts, low P
and low water
holding capacity
and rooting depth.
The soil pH here
was 4.5, not
directly limiting.
Revegetation Issues
• Very few coal refuse disposal facilities have
stored sufficient topsoil or suitable spoil
materials to cover these piles for
revegetation.
• Current federal and state regulations allow
direct seeding, but only with sufficient
proof of concept and appropriate testing of
the refuse materials.
Incorporation of 45 Mg/ha
lime on sulfidic coal waste
materials.
Wise Co. coal refuse with P.A. = -15 tons/1000.
Effects of 10 Mg/ha Lime plus
50 Mg/ha Papermill Sludge on
Acidic Coal Refuse
Direct seeding results after 3 years with lime, high P and 80 Mg/ha
biosolids and acid/salt tolerant seed mix. The tall plants are native
annual invading into the plots.
Coal Waste Revegetation Criteria
Daniels et al., 2000, Agronomy Mono # 41
• Where liming is practical (PA < 50 Mg/ha and
slopes < 25%), direct seeding is feasible with
heavy P (400 kg/ha) and mulch applications, and
via the use of acid/salt tolerant species like
Festuca rubra, etc.
• Additional organic amendment with biosolids or
composts is highly recommended at > 100 Mg/ha,
incorporated.
Coal Waste Revegetation Criteria
Daniels et al., 2000, Agronomy Mono # 41
• Coal refuse materials with PA > 50 tons
per 1000 will require soil or spoil covers
of up to 0.5 m depending on acidity.
Adding a lime “blanket” at the refuse/soil
contact significantly decreases the
thickness requirements.
Pb/Zn smelter slag site in Katowice Poland in 1994. Some
materials were > 1000 ppm water soluble Zn, and > 90 ppm water
soluble Cd with very high soluble salts (EC)
Result s from Stuczynski et al. 2007
Most of Poland protocols were originally specified by
Rufus Chaney based on his work (with Jim Ryan, Sally
Brown, etc.) on USA Superfund sites as shown here.
Mixing/Staging Area used to mix biosolids and wood ash; seeded
when completed; Jim Ryan & Rufus Chaney during 1999 visit.
However, most of our success in
Poland was due to Tom Stuczynski
Palmerton, PA 1999; Untreated area adjacent to revegetated area of
Blue Mountain, with John Oyler and Tom Stuczynski.
Application of waste lime (partially neutralized
CaO from acid mine water treatment) and
biosolids to site per prescription by Chaney,
Daniels, and Stuczynski.
Biosolids application at 150 to 300 tons/acre (N leaching not
a concern here!). Black waste is Welz; redddish material is
from Doerschel process.
Site in spring of 1995 following fall seeding with acid/salt tolerant
grasses. Salty area in left rear had EC > 16 ds/m!
Data from
Welz plots
Reverse view of same site in June 1996. Salty area (Doerschel) is
now in foreground after being capped with 15 cm of waste lime
plus another 300 tons per acre of biosolids and reseeded in fall of
1995. Working with Polish authorities was “interesting”.
Welz portion of Site in August of 2004. Bare strips are
untreated alleys. Some trees were planted, many invaded.
Non-acidic Pb/Zn tailings in Poland with EC > 5
mmhos/cm and water soluble Zn > 1000 mg/L.
Pb/Zn processing tailings
revegetated in 1997 via similar
approach.
Overview of fall 1994 plots from old photo location. Welz plots in middle ground;
Doerschel plots in background have been removed by re-mining
High lime + biosolids plots on Welz waste after 15 years
View down over 2 ha demonstration area; species trial area is to right, just out
of photo. This was 12 years old.
Demo plots on Pb/Zn tailings. All trees have invaded. Up to 40% of live cover
is local invading species.
Stafford Regional Airport in Winter of 1999/2000.
After 2 conventional revegetation efforts.
NRCS Flood Structure
on Tributary Of Potomac
Cr. Waters discharging
here in February were
pH 3.0 with 10 ppm Fe,
40 to 50 Al, 150 sulfate,
etc.
Prior to
remediation,
water
sampled at
the pond
drainage had
a pH of 3.3.
Results from Orndorff et al. 2008
Potomac Pond - an NRCS
stormwater retention basin
about 1.5 - 2.0 km
downstream from SRAP.
Preliminary assessment soil pH was 3.6 and predicted lime
demand (potential acidity) averaged 15 tons per acre per 6
inch depth of soil to be neutralized. Many areas tested in
excess of 45 tons per acre lime requirement.
Erosion of acid sulfate sediments and acidic leachate from
an adjacent spoil fill has severely impaired this wetland.
Pre-construction active beaver colony was
maintaining 4 dams with 2 lodges. Water here was
pH 2.9 with 240 ppm Fe at first sampling in 2001!
Shallow
groundwater
monitoring
well.
SW6
Drainage from SRAP prior to remediation (April 02)
Iron-staining on
concrete culvert
at SRAP
Large open hole in galvanized
water control structure allowing
direct bypass of acidic sediments
Corrosion of metal pipes in drainage basin at SRAP.
Soil Revegetation at SRAP
o A mixture of lime-stabilized biosolids
(24 to 52% CCE) was applied in
March, April and early May of 2002.
o Loading rates were based on predicted
lime requirements of the sulfidic soils
and ranged from 50 to 175 Mg/ha of
dry biosolids - average loading rate
was around 70 Mg/ha.
Spreading biosolids at SRAP
(April, 2002)
Overview of site in June,
2002. Area in foreground
was incorporated and seeded
by mid-April. Area in
background was not
completed until late May.
Area revegetated in late May as it
appeared in July, 2002. Unfortunately,
April through October of 2002 was the
hottest/driest period on record.
Same view after fall re-seeding (2002)
and a reasonable weather year.
Soil acidity after reclamation
samples collected September
2003
o Surface soil pH: 6.10 - 7.77
average = 7.26.
o Subsurface soil pH: 2.71 - 4.56
average = 3.49.
o A productive topsoil has been
established but continued maintenance
will be necessary.
Same view in summer of 2004 after site
had been mowed four times.
Water quality - pH and
metals
o Airport construction had significant
negative effects on local surface
water quality due to acidity and the
release of metals.
o Water quality was immediately
affected by the application of limestabilized biosolids.
M
ar
-0
2
Ap
r-0
2
M
ay
-0
2
Ju
n02
Ju
l-0
2
Au
g02
Se
p02
Oc
t-0
2
No
v02
De
c02
Ja
n03
Fe
b03
M
ar
-0
3
Ap
r-0
3
M
ay
-0
3
Ju
n03
Ju
l-0
3
Au
g03
Se
p03
Oc
t-0
3
No
v03
De
c03
Ja
n04
Fe
b04
Nitrate-N and Ammonia-N (mg / L)
15
pH
30
Potomac Pond Discharge
9
Mar-02 through Feb-04
8
25
7
20
6
5
4
Nitrate-N
10
Ammonia-N
0
Date
3
pH
2
5
1
0
Water quality - pH and
metals
o The pH values have increased - most
sites are maintaining pH values > 4,
many are in the 5’s and 6’s.
o Dissolved metals have decreased Fe in water discharging from the
airport has been < 5 mg/L for the
past 10 years.
Relative Risks?
o Biosolids applied at elevated rates
to acidic sloping sites will pose a
runoff risk, especially if you don’t
have active vegetation to take up
water soluble N forms. Ammonium
loss is also enhanced in very acidic
soils.
o That being said, no P runoff
occurred.
Which is worse: pH 3.0 acid
mine drainage or pH 7.5 water
enriched in N for a few months?
Remediated yard, summer 2006
Neighbor’s yard, Summer 2006
Summary Points
• Coal refuse, and metal mining processing and
smelting generate a wide array of wastes and
difficult remediation challenges.
• Addition of lime + OM will generally stabilize
most heavy metal (e.g. Cu, Ni, Pb) related
challenges. Note: Zn can/will remain phytotoxic in
sulfate dominated systems unless you drive the
pH > 7.5. Chaney’s mantra is “make it
calcareous”!
• However, certain oxyanions (e.g. Mo and As) will
be enhanced in mobility at high pH, so other
approaches to fix or sorb them should be taken.
In some instances, you may need to actually lower
pH, add Fe+P, etc.
Summary Points
• Most of these sites will have more than one
(complex mixtures) of elements that are
potentially toxic, so your characterization and
remediation plan must be comprehensive.
• Liability release criteria for these sites are often
based on total metal/toxic concentrations in soils
which may be very hard to meet. We need new
criteria that really assess the relative
“bioavailability” of metals etc. linked with
appropriate risk assessment.
2007 EPA “White Paper
Report” on how to match use
of soil amendments to
stabilize and remediate the
full range of mining wastes
and sites.
This document has the most
up-to-date and easy to
understand approach to
understanding what
metals/toxicities must be
remediated by mine type and
what treatment interactions
will be.
http://www.clu-in.org/download/remed/epa-542-r-07-013.pdf