Innovative Use of GlassCullet in EnvironmentalRemediation

Delaware Gasoline Cleanup

• Apex contracted to cleanup gasoline spill at retail facility in southern Delaware.

• Site conditions suitable for combined airsparging and vacuum extraction system (VES).

• VES targeted gasolinein unsaturated soils.

• Glass cullet an integral partof VES extraction pipe networkconstruction.

Vacuum Extraction Systems – A Quick Primer

• A VES draws soil vapor out of the impacted unsaturated zone via a vacuum pump.

• The vacuum pump mustbe “connected” to thesubsoils via some typeof perforated pipenetwork.

Vacuum Extraction Systems – A Quick Primer

• Extraction networks commonlyseries of vertical screened “wells” or occasionally horizontalnetworks of perforated pipe

Vacuum Extraction Systems – A Quick Primer

• To facilitate better “connection” of the extraction network of wells or pipes to native soils, the extraction network is surrounded by apermeable fill.

• The permeable fill acts to :Improve the vapor removal efficiency of the VES by increasing the cross sectional flow area around the extraction pipe,Prevent influx of fine sediment, especially during fluctuating water table conditions, andSupport the extraction pipe, especially in horizontal systems.

VES Permeable Fill

• The typical fill material used is a silica or carbonate based, coarsesand to fine gravel, usually well rounded and well sorted/poorlygraded…..crushed stone or pea gravel.

• Natural aggregates are theconvention because that’swhat the typical remediationdesigner understands to beavailable, functional andcost effective.

Glass Cullet Application

• Site located near Ocean City, Maryland, close to a tidal inletnear sea level.

• Gasoline release at dispensersimpacted soil and groundwaterwith separate and dissolvedphase gasoline constituents.

• High water table and thin vadosezone promoted use of horizontal VES pipe network.

Glass Cullet Application

• Horizontal network of perforatedpoly-corrugated drain pipe installedaround existing USTs, formerdispensers and down gradient pathof product veneer on water table.

Glass Cullet Application

• Glass cullet placed aroundentire length of VES pipenetwork, forming anencapsulating, permeablesupport system for the pipe.

Glass Cullet As VES Permeable Fill

Glass cullet was an excellent replacement in all respects:

Agency ApprovalLogisticsPermeabilityStrengthCostVES & MacadamPerformance

DNREC Approvalof Glass Cullet

DNREC approved use of the glass cullet with out need for permit.Apex presented to DNREC a brief review of batch and vendor specific cullet characteristics:

PermeabilityStrength

Leachate potential not a concern.

Logistics

• The Town of Ocean City, Maryland had ready supply of two sizes of glass cullet available for use. “Coarse” fraction appeared best for VES application.

• Acceptable Glass:BottlesJarsFood containersMirrorsWindow glassClay & ceramicsOvenwareDishesCrystal & decorative glass

Permeability

• To assess glass cullet compatibility with the aquifer matrix (native sediments below the water table), Apex compared sieve analyses and permeability tests of samples of each media.

• The available glass cullet for the project proved to be slightly coarser than the native aquifer materials and slightly more permeable….the right combination.

Permeability – Aquifer Sediments

• Two samples of aquifersediments from twolocations on site werelab sieved whichindicated predominantlypoorly-graded (well sorted)Sand (SP) to Sand withSilt (SP-SM).

Permeability – Aquifer Sediments

• The hydraulic conductivity of a composite sample of the two locations, recompacted to simulate shallow burial (< 10 feet), was measured at 7.6 x 10-4 cm/sec or 2.2 ft/day.

Permeability – Glass Cullet

• Four samples of OC’s coarseglass cullet lab sieved todetermine grain size:

Two samples as received (AR),One sample as received aftercompaction (AR/PC),One sample, coarse fractiononly, after compaction (CF/PC).

• AR: Poorly-graded (well sorted)Sand with Gravel (SP).

• AR/PC: Well-graded (poorlysorted) Sand with Gravel(SW).

Permeability – Glass Cullet

• The hydraulic conductivity of the AR/PC was lab determined to assure the permeability of the GC was was still sufficient once the GC was emplaced and compacted around the vent pipes.

• OC’s AR/PC measured at 1.1 x 10-3 cm/sec or 3.1 ft/day, relative to native sediments at 7.6 x 10-4 cm/sec or 2.2 ft/day.

Strength

• Strength tests of Pennsylvania suppliers’ glass cullet similar in size to OC’s GC, indicate standard compaction (ASTM 698) on the order of 93 to 111 lb/ft3.o As a general rule, GC displays similar strengths as natural

aggregate of the same size.

• Lab compaction of OC’s GC indicated the glass could withstand considerable compaction, yet retain a coarse enough matrix to be stable and permeable.

Cost

• Ocean City’s glass cullet cost at the time of the project was $ 10/yard, delivered. This was approximately half the cost of processed, natural aggregate offered by local quarries.

• The total amount of glass cullet used for the project was approximately 18 yards, for a total cost of $180.

VES Performance

• Solid proof glass cullet has performed since installation is:

VES performanceMacadam performance

• VES regenerative blower operating at peak capacity in the range of 120 cfm under approximate vacuum of 10 inches of water (WC).

Macadam Performance

• Since system installedresurfaced macadamhas not experienceddifferential settlementof any kind. Glasscullet and naturalaggregate performingas unified, stable system.

Summary – Glass Cullet As VES Permeable Fill

Glass cullet was an excellent replacement in all respects:

Agency Approval – DNREC approved with out need of permitLogistics – Town of Ocean City had GC available for lessPermeability – better than site sedimentStrength – as good as similar sized

natural aggregateCost – half the cost of natural aggregateVES/Macadam Performance – optimum

VES performance and no settlement.