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You are an environmental consultant who has been asked by your client, the real

ID: 235014 • Letter: Y

Question

You are an environmental consultant who has been asked by your client, the real estate division of Rupt Bank to perform an ASTM Phase II Limited Subsurface Investigation at a site of a 40 acre future residential development, 400 unit townhouse complex.  The history of the site is somewhat sordid, in the early 1900’s it was the site of a urban dump.  In the 1920’s it became a military fuel storage depot.  In the 1940’s a residential subdivision was built but abandoned after several house exploded due to a series of what was thought to be natural gas explosions.  The site was redeveloped as a shopping plaza in the 1960’s which had a supermarket, on-site dry cleaner, gasoline service station, restaurant and office building.

You need to determine where each of the former uses was located on the site, you need to create a sampling plan to determine what types of chemicals you will be testing for and in what matrix (air, soil or groundwater), how many samples, and what do you hope to determine from the results of this study.

Remember that this will be used for residential housing.

What are some of the methods that can be used to clean up soil and groundwater at this location?

Explanation / Answer

For the ASTM subsurface investigation investigation we require

Geological and hydrological setting of the area

access utility locations whether underground or overhead

soil or rock type

surface condition of the area i.e. lack of vegetation, ponded water, evidence of rock/soil failure

Geomorphology of the area i.e floodplain, landslides, karst topography etc.

drainage of the area/ flood level

property use

depth of the foundation

Chemicals tested if they are present in acceptable level in the area by drilling boreholes, trenches, ground water monitoring wells.

Metals like arsenic, cadmium, chromium, lead, mercury, selenium and silver

polychlorinated biphenyls

semi volatile organic compound

volatile organic compound

pesticides

diesel range organics

oil and grease

Soil and ground water treatment

Soil

Bioremediation: in this method microorganisms are put into soil which help in breakdown of organic contaminants in soil or groundwater. oxygen generally used as an additive

Bioventing: in which oxygen is blown into the soil since oxygen helps in better growth of bacteria which helps in beakdown of contaminant like gasoline

Incineration: soil which contains hazardous substance is burned at a moderatly low temperature results in safe products

Ground water

Pump and treat: In this contaminated ground water is pumped out and then passed through the filter which removes the contaminated substances and then it is ultimately returned to the groundwater

Air sparging: Air is forced downwater into the contaminated ground water. Air moves horizonatlly as well as vertically into the groundwater making an underground stripper which removes contaminants by volatization and the airbubbles passed the contaminated groundwater to the vapour extraction system.