In-Situ Remediaton

Removal of 1.500 m3 LNAPL

Jack van RossumRonny Hilhorst

Hannover Milieu- en Veiligheidstechniek

SPE ViennaFebruary 23th, 2011

Contents Presentation SPE

• Introduction HMVT• Case: LNAPL removal in the Port of Antwerp

– Site information– Soil & Pollution

• Shallow LNAPL– Tender– Remediation approach and system– Remediation Equipment– Water and air treatment– Results

• Deep LNAPL– Remediation approach– Results & costs

HMVT: Experts in-situ soil remediation

HMVT

• Experts in in-situ soil remediation, water and air treatment

• Excavation, extraction, biological and chemical techniques

• Since 1988

• 45 Employees

• Offices in the Netherlands and Belgium

• Member of Antea group

• Advise, Design, Pilot & Bench scale testing

• Contracting, Operation & Maintenance

• Risk based contracting

Brief description location

Site information

Oil and chemicals storage terminal in the port of Antwerp

• Storage tanks

• Pumping stations

• Contractors village and other buildings

• Underground and above ground pipelines

• Roads and railways

• Contamination caused by leakage at pumping station (naphta) and a storage tank (diesel)

Site LNAPL

Brief description soil

Site information: Soil

• Ground level has been raised up to 4 – 6 meters with sandy

material for port constructions

• Original clayey soil is still present (5 – 7 mbgl)

• Groundwater level 2,5 mbgl

• Groundwater level fluctuates ca 1 meter between summer and winter

• Debris of former village on clay layer

Brief description contamination

Contamination

Contamination: LNAPL of naptha & diesel

• Estimated LNAPL about 1.000 m³

• Area with LNAPL about 23.000 m²

• Thickness LNAPL > 1 meter

• Hugh contamination of soil and groundwater

• Shallow and deep LNAPL

Surface area LNAPL

Cross section LNAPL

Brief description tender

Tender

• Limited tendering started in 1999

• Two principals

• Open tender, consultants did not know a good remediation

approach (Design & Construct)

• Air and groundwater treatment must be able to treat also other

gas and water of the customer

• Existing buildings and equipment must remain in function

• High demands on safety (ATEX) and operation

• Design, negotiations and safety aspects took 1,5 year

Design Remediation System:

• Multi Phase Extraction:

• 950 MPE-filters, two levels (2,5 – 3,5 and 3,5 – 4,5 mbgl),

• Soil vapor and groundwater extraction:

• 25 combined filters for soil vapor- and groundwater extraction (6 mbgl),

• Deep groundwater extraction:

• 3 deepwells (15 mbgl),

• Airsparging:

• 43 injection filters (6 mbgl),

• about 35 km underground tubing!

Remediation system

Remediation system

Combined filter

MPE shallow

MPE deep Airspargi

ng

Original clay

Design Remediation Equipment:

• Multi Phase Extraction

• 4 MFE-units, capacity 200 Nm3/hr, knock out pot to separate extracted water, LNAPL and soil vapor,

•Groundwater extraction

•Shallow: 2 Piston pumps, total capacity 10 m3/hr,

• Deep: 3 Piston pumps, total capacity 7,5 m3/hr,

•Soil vapor extraction

•Blower, capacity 450 Nm3/hr with knock out pot,

•Airsparging

•1 Compressor, capacity 200 Nm3/hr

• All installations ATEX

Remediation Equipment

Remediaton Equipment

Water treatment

Water and product treatment system:

• Capacity 25 m³/hr,

• 2 Oil/water separators in sequence,

• 1 Product tank,

• 3 Stripping towers in sequence,

• 2 Rotating biological contactors,

• 1 Activated carbon vessel,

• Sediment pond,

• Discharge pump to public sewer system,

• Water treatment also used for other water.

Water treatment

Air treatment

Air treatment unit (6.500 m3/hr):

•Incinerator, capacity 100 kg product per hour,

•Flow variable between 3.000 en 6.500 m3/hr,

•Oxidation at a temperature of 720 degrees Celsius, gas-fired,

•Heat exchanger to reduce gas consumption,

•Treatment air from:

•MPE

•Soil vapor extraction

•2 Stripping towers

Air treatment

Results and costs

Results product removal

• Period 2001 – 2006:

• 700 tons gas phase (MPE and SVE) incinerator

• 310 tons liquid phase (oil; mainly MPE)

• 80% oil layer removed (surface)

• Period 2006 – 2008:

• 225 tons gas phase

• 95% oil layer removed (surface)

• In 2008 focus changed from LNAPL removal to stimulation of biological degradation (airsparging and SVE),

• Total costs from start till 2008 (LNAPL removal):

• € 29,-/m3 contaminated soil or

• € 3,-/liter removed product.

Deep LNAPL removal

Hier 2e dwarsdoorsnede van Marco invoegen

Remediation approach deep LNAPL

Tender and remediation approach

• Residual deep oil layer: 1.200 m2, 5 – 7 mbgl

• All obstacles will be removed new tanks

• HMVT made an overview and cost estimate for all possible remediation approaches

• Based on this overview the client decided to excavate the deep oil layer

• Based on the cost estimate the 2 responsible principals made a deal about the costs

• HMVT made a detailed design, including an alternative sheet pile

Results and costs

Results product removal

• Sheet pile: 190 m1 / till 10 mbgl

• Groundwater extraction:

• Deep and shallow, total 50 m3/hr

• Treatment in existing and extra water treatment

• Excavation:

• Excavation 15.100 m3 ground,

• 4.122 tons polluted ground treated

• The work was performed within the timetable

• Cost saving: € 130.000 for the client

Deep LNAPL removal