pH

pH levels are a fundamental influence in contaminant solubility and on-site determination of pH is often requested as a matter of course when determining other contaminant levels especially heavy metals.

Sulphate

Historically sulphur contaminated wastes originated primarily from the sour gas sweetening industry, though more recently gypsum based waste products such as plaster board have become more prevalent.

Careless disposal of sulphur containing wastes may result in acidification of both soil and groundwater and hence sulphate consequently is a contaminant of interest to waste acceptance facilities. Additionally, concrete structures in contact with the ground are adversely affected by high sulphate levels and hence the construction industry is also concerned with levels of this contaminant.

QROS is more frequently being asked to determine water soluble sulphate on-site. To achieve this we use a turbidimetric system after an on-site soil extraction. Values are reported in mg/kg of soil fresh weight and a genuine QROS generated on-site report can be seen above, alongside UKAS accredited data conducted on the same extracts. Standard limits of quantification for water soluble sulphate are generally  requested to be 650 ppm, well below the 1000 ppm limit for inert classification although lower limits can readily be achieved upon customer request.

Chloride

Chloride is another contaminant that QROS frequently tests for on-site. The dominant source of contamination by chloride is rock salt from roadside stores or transfer stations, though there may be other sources such as historical contamination from PVC production facilities.

QROS are able to determine soluble chloride levels rapidly and easily on-site using a titrimetric method capable of determining down to 400 ppm, well below the inert classification of 800 ppm. Lower determination limits are achievable upon customer request.

Phenols

Phenols (sometimes called phenolics), are a class of chemical compounds consisting of a hydroxyl group (-OH) bonded directly to a benzene ring. Although similar to alcohols they are not classed as alcohols because the hydroxyl group to which it is bonded does not contain a saturated carbon,  and as such have unique properties. Their acidity levels are higher due to the nature of the aromatic ring's tight bond with the oxygen atom and a relatively loose bond between the oxygen and hydrogen.

With respect to contaminated land the most common source of phenolic compounds encountered comes from creosote (derived either from wood or coal). the hydrocarbon analyser developed by QROS has the ability to differentiate between these two sources of creosote.

We also offer an on-site technique to quantify general phenolic compounds. The technique will detect and semi-quantify monohydric phenols and some dihydric phenols giving results in the region of ten minutes. The result is equivalent to the standard AAP method for phenol analysis: US EPA method 420.2 (1983) Phenol in water and waste. The reported value is also referred to as the phenol index.

Contractors

As a contractor it will often be in your best interest to keep the project moving and within or ahead of the client's schedule. From your prospective onsite analysis can best be thought of as a site management tool. It will allow you to make rapid decisions on waste disposal options and to delineate contaminated area far more effectively, helping you reduce disposal cost and keep within or under the quoted project costs. This can be achieved as simply as real time designation of excavated waste, meaning no or reduced stockpiling and allowing site work to proceed unhindered, to rapid confirmation that an excavation is complete and that all the contamination has been removed, backfilling can commence and the project proceed.  This scenario also has implications for health and safety in that excavations are not left open waiting for laboratory results to confirm that the task has been completed satisfactorily.

Chlorinated Solvents

Chlorinated hydrocarbons (organochlorides) are a very large and diverse group of hydrocarbon molecules that also have at least one covalently bound chlorine atom chemically bonded to them. The number of carbon atoms and its consequential three dimensional arrangements as well as the number of chlorine atoms attached will determine the chemical and physical properties of the chlorinated hydrocarbon formed. There is an immense number of possible forms of chlorinated hydrocarbons, allowing this class of compounds to have an extensive range of applications that are of significant economic and practical importance.

Chlorinated hydrocarbons are used predominantly as solvents and have historically been used as industrial de greasers, in fire extinguisher and as refrigerants. They are colourless, volatile liquids with a moderately sweet aroma and partially soluble in but denser than water.

The more common forms of chlorinated solvent contamination of soils and ground waters include;

Tetrachloroethene (PCE, Tetrachloroethylene)

Carbon tetrachloride (Tetrachloromethane or carbon tet)

Trichloroethylene (TCE,Trichloroethene)

1,1,1 - Trichloroethane (TCA, methyl chloroform, chlorothene, Solvent 111)

Dichloromethane (DCM or methylene chloride)

QROS currently utilises two methods to quantify /semi-quantify their presence in soils. The first of these uses a diffusion tube technique which in conjunction with a modified extraction protocol can quantify chlorinated solvents to ppm levels. Determination takes approximately 10-15 minutes and gives an absence/presence indicator, with a Minimum Detection Limit of 10 ppb in water and 0.5 ppm in soil. The method is unable to differentiate between chlorinated solvent types and the data produced assume a given 'typical' mixture of solvents is present. If the contaminate is known to be a single Chlorinated hydrocarbon then quantification can be based on that assumption and a more accurate concentration determined, and like wise for a mixture of chlorinated hydrocarbons if the relative ratios has previously been determined.

A further technique currently under development within QROS utilises a positive ion heated diode system and is sensitive to levels as low as 0.005 ppm and not susceptible to interferences from BTEX or other volatile hydrocarbons. The sensor is also unaffected by moisture levels that would quickly destroy a PID lamp. The unit can be operated as either a "sniffer" providing semi-quantitative data that can be used to identify gross contamination, or as a discreet analyser to provide more quantitative results. The analyser is completely portable and can operate for a day before battery recharge is required

Ammonium

Ammonium ions are generated by ammonia reacting with proton donors. When ammonia is dissolved in water, a significant amount of it reacts with the hydronium ions in water to give ammonium ions.  Ammonia contamination is often historic in nature and often found on old coal carbonisation plant sites

QROS offer an on-site technique that allows us to quantify the level of exchangeable ammonium in soil within approximately 30 minutes.

Also available are on-site techniques for the determination of soluble sulphate and soluble chloride

Other Contaminants

There are numerous more contaminants to be found in soils and QROS prides itself in being able to provide a method that can realistically be conducted on-site, the following is just a selection.

If you have a contaminant that is not detailed
here please call us to see if we have one.