Chemical injection is a specialised field of in situ technology and is one of the environmental remediation techniques used by InSite for soil and groundwater remediation.
InSite is an industry leader in the application of various chemical injection strategies; including using in situ chemical oxidation (ISCO), oxygen release compounds (ORC), and in situ chemical reduction reagents (ISCR).
InSite owns and operates all of its own chemical injection equipment including skid mounted and modular mixing hoppers and tanks, variable speed pumps, hoses, well heads, manifolds, flow gauges, safety equipment, and monitoring equipment.
Services include the procurement and safe storage of chemicals, mixing and preparation, chemical application, and monitoring groundwater parameters.
CASE STUDY: ISCR injection for remediation of a former dry-cleaner site
At a site which was under construction in the southern suburbs of Melbourne, 34,000 litres of mixed EHC© in situ chemical reduction (ISCR) reagent was applied to 13 injection wells using InSite’s skid-mounted chemical mixing and injection unit.
The reagent solution comprised three chemicals: ELS™ Microemulsion, EHC© liquid mix, and potassium bicarbonate. These were mixed with water to create batch quantities of approximately 950 litres, which were applied to up to 4 wells simultaneously.
As a result of the very tight geology associated with some of the wells, pressure injection at approximately 100 kPa was required in some areas to ensure the distribution of the ISCR reagent.
CASE STUDY: ISCO chemical injection
InSite managed an in-situ chemical oxidation (ISCO) chemical injection program including the procurement and safe storage of chemicals, mixing, injection, and monitoring of reagent and groundwater parameters.
A series of four ISCO events over a period of two months involved the injection of 5,400 kg of sodium persulphate and 9,000 L of sodium hydroxide solution into 15 injection wells at a vacant service station site in suburban Perth.
A secured works compound was established on site using temporary fencing, bollards, and bunting. InSite established temporary power on site, along with a clearly defined ‘hot zone’, emergency shower, eyewash station, administration office, and crib area.
The 900 litre batches were prepared in the mixing tank and pre-injection feedtank, before being applied to 5 injection wells. Digital flowmeters connected to each well were used to monitor injected volume and instantaneous flowrate during the events.
CASE STUDY: Pulsed chemical injection combined with multi-phase extraction
InSite was engaged to undertake a program of simultaneous chemical injection and multi-phase extraction at a former service station in Perth, WA. The site had a number of operational limitations including; restricted access, a narrow plant set up area, neighbouring retail and commercial businesses (which operated throughout the works program), and constant through traffic in the injection zone from an adjacent four-lane highway.
The 6-day injection program included injecting 4,350 kg of sodium persulphate, and 33,325 litres of hydrogen peroxide using InSite’s specialised chemical injection unit. Pulsed injection of each chemical was undertaken to ensure full activation within the source zone. Pressure relief systems and constant monitoring, resulted in a safe and successful injection program.
For one day on either side, and throughout the injection works, InSite also undertook multi-phase extraction, removing 44,200 litres of contaminated groundwater from the site.
