utilization of biosolids and other residuals for remediation of phytotoxic materials

W. Lee Daniels

Utilization of Biosolids and other Residuals for Remediation of Phytotoxic Materials

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 S-facing 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.

Effects of 10 Mg/ha Lime plus 50 Mg/ha Papermill Sludge on Acidic Coal Refuse

Wise Co. coal refuse with P.A. = -15 tons/1000.

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

Mixing/Staging Area used to mix biosolids and wood ash; seeded when completed; Jim Ryan & Rufus Chaney during 1999 visit.

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.

Palmerton, PA 1999; Untreated area adjacent to revegetated area of Blue Mountain, with John Oyler and Tom Stuczynski.

However, most of our success in Poland was due to 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.

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.

Stafford Regional Airport in Winter of 1999/2000.

After 2 conventional revegetation efforts.

Potomac Pond - an NRCS stormwater retention basin about 1.5 - 2.0 km downstream from SRAP.

Prior to remediation, water sampled at the pond drainage had a pH of 3.3.

Results from Orndorff et al. 2008

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!

Drainage from SRAP prior to remediation (April 02)

Shallow groundwater monitoring

well.

SW6

Iron-staining on concrete culvert

at SRAP

Corrosion of metal pipes in drainage basin at SRAP.

Large open hole in galvanized water control structure allowing direct bypass of acidic sediments

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 reclamationsamples collected September

2003o Surface soil pH: 6.10 - 7.77

average = 7.26.

o Subsurface soil pH: 2.71 - 4.56average = 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 lime-stabilized biosolids.

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Potomac Pond Discharge

Mar-02 through Feb-04

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