Tracer test results and particle size analysis of Lower Permeable Reactive Barrier (PRB), Main Powerhouse site, Casey Station.

Brief description

A permeable reactive barrier (PRB) was installed downgradient of the Main Powerhouse at Casey Station in 2005 in order to contain and treat fuel contaminated water arising from a fuel spill that occurred in the area in 1999. The PRB consists of a funnel and gate system with 5 "cages" containing a variety of remediation media used to assess the suitability of this media. Each "cage" contained three stages of remediation media:

Stage 1: Nutrient release: Nutrient (nitrogen) enriched zeolite (called Zeopro TM) was placed at the front of the PRB and released nutrients into any water entering the PRB in order to enhance biodegradation of hydrocarbon contaminants in the PRB.

Stage 2: Hydrocarbon Capture: A mixture containing Granular Activated Carbon (GAC) was placed in the middle of the PRB and was used to "capture" any fuel in the nutrient enriched water. Native microroganisms then use the nutrient supplied in the water to degrade the fuel captured on the GAC

Stage 3: Nutrient Capture: Zeolite amended to recapture any nutrients in the water prior to the water leaving the barrier into the surrounding environment.

To monitor the PRB, 8 multiports were installed in each Cage to obtain water samples from the PRB. Each multiport location could be sampled from 4 depths in the PRB. See the attached Journal Paper (Mumford et al. 2014) for detailed diagram showing multiport names, locations and PRB media combinations (GAC, zeopro, zeolite etc) in each cage.

In 2009/10 the PRB media was excavated and sampled in detail to assess hydrocarbon concentrations in the media and particle size analysis (See attached journal paper)

The attached excel data provides the particle size distribution data from the 2009/10 sampling event. The column headings are:

SAMPLENO: Internal tracking number. Not needed
SAMPLEID: Sample Barcode assigned as part of the AAD's Sample Tracking Database except where labelled Zeolite, Zeopro or GAC which indicates a sample of "raw" unused media was tested as reference.
Sample User Label: Provides detail of the sample location and depth in the following sequence: Sample Type, Cage #, Profile #, Depth in mm, sampling type. Profile # was determined by dividing the length of each cage in to 10 sections (45 mm each) from which the material sample was taken. Measurements are from the front (upgradient) side of the cage. The 10 Profiles were:
Profile 1: 65-110 mm
Profile 2: 240-285 mm
Profile 3: 415-460 mm
Profile 4: 590-635 mm
Profile 5: 765-810 mm
Profile 6: 940-985 mm
Profile 7: 1115-1160 mm
Profile 8: 1290-1335 mm
Profile 9: 1465-1510 mm
Profile 10: 1640-1685 mm

For example Sample User Label "BM, 1, 1-2, 250, Bulk" means Barrier Material, Cage 1, Profile number (distance from front of cage between 65 mm and 285 mm, 250 mm depth from top of cage, Bulk Sample)

Dry wt: Dry weight of sample in grams
CB No. Order samples were run
Sed Fraction: Sediment fractions (grain size fractions in microns) by weight (grams). 7 grain sizes were measured less than 63 microns, 63-125 microns, 125-250 microns, 250-500 microns, 500-1000 microns, 1000-2000 microns and greater than 2000 microns
Sed Fraction by %: Previous 7 columns converted to % of sample based on total weight of sample

These data were collected as part of AAS project 4029, but AAS project 4036 was also involved in obtaining the samples and using the findings).