Feb. 2006 IHA/pm 1

Site remediation 1

Planning site remediation

Excavation:

Pros/cons & How

Feb. 2006 IHA/pm 2

After this lecture you should

• Understand the concept of differentiated and SMART goal-setting for remediation.

• Understand the main elements in strategies for remediation of contaminated sites.

• With respect to excavation understand the• advantages and disadvantages of this method

• Know key methods for soil excavation

• Know tools and basis for price calculation

Feb. 2006 IHA/pm 3

Goalsetting for the remediation

How clean??

What’s the purpose of the remediation?

Legislation (law on contaminated soil):Registration if the contamination can cause harmful effects on humans and

the environment (§5), and that the purpose is to

“…reestablish previous conditions..”

the Guideline (EPA 7/2002, section 2.4): “..the aim of the remediation is to remove contaminants. Limit exposure or prevent the spread of contaminants to soil, water or air”

“SMART” goals for the remediation are required on this basis.

Feb. 2006 IHA/pm 4

Differential Goal setting

Goal Description

Restoration Complete removal of contamination

cf. “…reestablish previous conditions..”

Mass reduction Best available technological (BAT) reduction of the contamination (if complete removal is not realistic / possible)

Control Risk reduction. Partial removal of contamination and/or reduction/control of contaminant mobility.

Monitoring For observation of low risk contamination

As proposed by Loren Ramsey at ATV meeting, March 2000

Feb. 2006 IHA/pm 5

Planning the strategy Different places – different goals & methods

Feb. 2006 IHA/pm 6

Risk removal principles

• Restoration: remove contamination (excavation....)• Mass reduction: Significant removal of

contamination. • Partial removal of contaminated soil• Degrade organic compounds in situ (stimulate)• Increase mobility – remove and treat (vapour or liquid)

• Control: Stop movement & transport (vadose / GW zones)

• (monitoring)OBS:Criteria of success: purpose, time, efficiency, cost.(Take care – consider risks ….)

Feb. 2006 IHA/pm 7

Land use. Strategies for elimination of risk:

For elimination of indoor and outdoor air quality risk • Soil replacement (excavation). (+/- on site, ex situ treatment)• In situ soil treatment• Groundwater in situ treatment or remedial pumping• Building construction measures (indoor climate)• Outdoor env. contaminant reduction

Feb. 2006 IHA/pm 8

Groundwater risk removal strategies

For protection of drinking water and recipients• Soil excavation (removal of contamination)• Active in-situ treatment of soil and ground water (source and

plume)• Remedial pumping strategies (+ treatment)• Immobilization at source

Feb. 2006 IHA/pm 9

Remediation 1: Excavation

Pro’s & Con’s:

+ Fast

+ Good documentation for result

+ Easy sampling along with removal of contamination

+ works for non-permeable soil (clay)- Depth limitations (cost)- Require access (distance to buildings)- Soil transport (reuse / treatment / dump ?)

Feb. 2006 IHA/pm 10

Excavation - clay

From : EPA Guidelines 7(2002) appendix 9.2

Feb. 2006 IHA/pm 11

Excavation – friction soils

From : EPA Guidelines 7(2002) appendix 9.2

Option: Piles per 1 m with steel reinforce-ment bars under foundation for support

Feb. 2006 IHA/pm 12

Free excavation (steep slopes)

Excavation tools:

Large Excavator

Small excavator

Vacuum excavation (loose soil)

Auger drills (Ø1,6 m!)

Semi horizontal drilling

From. Miljøprojekt 1032 (2006) “Fjernelse af jord-forurening ved og under huse”.

Feb. 2006 IHA/pm 13

Mini excavator & transporter – inside living room

Dry vacuum excavator truck

Semi-horizontal borings

Feb. 2006 IHA/pm 14

Large auger drills. Ø1 – Ø1.6 m

Feb. 2006 IHA/pm 15

Excavation + treatment

• On site / ex situ treatment (before dump / reuse): Destruction in soil / extraction + destruction / solidification

• Thermal treatment (power plants)

• Biological treatment (composting, land farming)

• Chemical treatment (oxidation, electrokinetic treatm.)

• Physical + chem/bio: forced leaching + water treatm.

Feb. 2006 IHA/pm 16

Price calculation

Important parameters:• Geology (friction soil, clay, soft soil?)• Situation of contamination (horizontal + vertical)• Type of building – need for stabilizing measures• Access to site and pollution (choice of equipment)

www.mst.dk miljøprojekt 1032/2006

1 2 3

4