Treatment riverbed soil contaminated by THC

[known100]

We know of a refinery that is seeking a solution for THC (Total Hydro-Carbon) contamination at their site.
It is along a river (close to sea, so a certain tidal effect is apparent and as well a salinity) and they are directed by the (relevant)authority to "clean up" contamination through the years.
Sepage or accidental spill or whatever (they never disclose the actual happenings!).
Now they have decided to dredge about 180,000 cubic meters soil; mainly silt and fine sand and place this in created receptors ( bund or dyke enclosed area on land).
Then the necessary treatment: HOW?
Finally the cleaned (to acceptable %) soil has to be placed back into the river. WHY? ..........
We may suggest them to keep this soil on land and settle/compact the lot and use for development.

My question is now:
How to do the cleaning method?
From the Internet there are scores of quite laborious methods with complete factory installations on site!
Not our dream!

Known100
(Marine Dredging)

 

[saxon]

known100, There are a couple of methods available. The dredged material can be incinerated and the THC destroyed through oxidation, or the material can be treated by microbes which breaks down the THC compounds through metabolism. Do a web search for any of these methods and also do search for environmental companies expert in this.

Hope this helps.
saxon

 

[cvg]

If this is in the US, you will need a 404 permit. Will your "cleanup" cause more harm than just leaving it in place? Can you just stabilize the material somehow so that it will stay in place?

 

[known100]

Many thanks to SAXON and 'CVG'.
Quite prompt reply and also highlighting the crucial points.

Indeed, I have done an extensive search (GOOGLE? YES!) with a great variety of question build-up.
EPA is good to guide.
THC is even the concatenation for "Toronto Harbor Commission"!
Although we can resort to the Client / Refinery Operator, telling him/them to sub-con that part and we just do the dredging.
But that minimizes the chance of getting the "overall" job.
And as acknowledged in my query, to set up a whole array of incinerators and sieves, washers, burners, bio-remediation hangars and/or laboratories, "isn't our dream".
I even came across a mobile treatment plant (in TULSA - Oklahoma).
I did collect a couple of FLOW-CHARTS with which we can guide the Client for an assessment of "Is it necessary and what next" strategy.
The local authorities simply say "Clean Up!".
We now have to extract data of the degree of contamination and the proper classification. (Nature may have changed some of the chemical indicators / composition!).
And in the meantime several new approaches and methods are "invented".
Underground pipes to deliver nutrient, bacteria, water and air.
The big three considerations remain:
1) Manage the site.
2) Cover the sediments in place.
3) Remove the sediments.
1) and 2) are easier said than done and for 'dry land' sites.
The Columbia University has done a nice research and solution for the annual removal of not less than 4.5 million cubic yards from the Port of New York!
(Beneficial use of dredged material as a filler in various applications). Still; treatment to be done though!
And to conclude: No, this project is not in the USA, nor Canada.

We keep searching for emulsifiers or "anti-dotes" and then probably set up a pipe system above the placed sediment in the receptor area and spray that 'kind of liquid' as they do till vegetable greeneries with water or fertilizers.

Greetings,
Known100
Marine Dredging.

 

[ferreiro]

Hi Known100,
We are looking at doing just what you have indicated,when we are completed the end result is nitrate rich soil.We call it land farming.

best
Robert

 

[4tuna]

It sounds like you are on the right track. "Active" treatments such as incineration will greatly increase your cost, but decrease treatment times. It depends on your objective. If cost is the primary issue, land farming is probably your best solution. Land farming typically involves addition of water and, depending on soil composition, nitrate or other trace nutrients to the soil to promote aerobic biodegradation. For many land farming applications, simple sprinkler systems ("rain-bird") are established as you would for your lawn. You don't necessarily need elaborate underground piping. Periodically turning the soil might be a better option to get oxygen to your soil, and will decrease your treatment time. With any land farming application, you need to be aware of local air quality regulations prior to starting, there may be some limitations on what you can do depending on your contaminant and concentrations.

I would recommend contacting a local environmental consultant who has experience in landfarming. They can give you more detailed advice on requirements and regulation in your area.

 

[dicksewerrat]

Land farming is probably the cheapest way to treat this soil. Running a disk throught eh soil every 2 months is a god way to add O2 and expose the soils for evaporation of HC's. however, land farming 180,000 Cubic meters will take a very large area. You only put down 3-4 inches of contaminated soil.

 

[known100]

9 October 2004.
Greetings to you all!

Many thanks to 4tuna and dicksewarrat.

4tuna: "It sounds like you are on the right track.

dicksewarrat: (Landfarming) - "a very large area needed".

The 'keyword' landfarming has helped me again to do I'net searches and it seems that bio-remediation is the best environmental solution after all.
Landfarming is indeed for large areas which we definitely do not have here.
The Client (and culrpit!) has just the shoreline perimeters of a river stretch of hardly 3 kilometers!
The inland area is occupied by indigenous and other rural folks. The other peculiar matter is of course that the soil is a layer of the riverbed! We now propose to (hydraulically) dredge this and place it in erected retention "ponds" with special high density poly sheet as bottom. Then mix this with natural bio-remediation material that will be imported. The tropical heat will help tremendously! Inceneration needs special installations and may cause new contaminants that will never be put down! Since there is also a lot of mangroves, we will suggest to utilize the remedied soil as a fill material where the mangrove is dead. Somehow you have to sell a plan!
Thanks again for the reaction and hope for more on the outstanding (I mean -without re-posting suggestions!)"Known100" postings, especially in the 'DREDGING'. It remains a marvellous Forum no doubt!

 

[orenda1168]

Known100:

A further option for consideration would be the application of a liquid multi-enzyme over the surface of spread-out dredged material which, with occassional tilling and enzyme re-application, will catalyze (via hydrolase cleavage of C-H bonds) the bio-oxidation of the THC's to acceptable levels in reasonably short order and at acceptable cost.

Orenda

 

[Smartech]

BEofre you decide on the method of remediation, you must first determine what is being defined as clean. In the US, we would start with human health and ecological risk assessments. The results of these evaluations can give a starting point for knowing what you are really attempting to do, then use environmental consultants(team with one for the proposal) to develop the remedial action plan.

 

[known100]

Contaminated riverbed soil:

To 'Orenda' and 'Smartech'
The suggestion of a treatment by liquid multi-enzyme is new to me and I will haraz *GOOGLE* again!
It might be a "orendous" (like that pun?) solution.

To 'Smartech':
It was actually the HUMAN affecting aspect that caused this concern and immediate action order by the Authorities!
May I quote:
Phase III assesment: --using a Risk Based Corrective Action (RBCA) approach to develop remedial actions and site management decision making".
AND: - " Given the limited data; the Dutch International Values for mireral oil (TPH) in soils of 5000 mg/kg was used as a Risk Based Screening Level (RBSL) for ecological risks to the river for hydrocarbon contamination of sediments".
NOTE: Observations made were: Using the TPHCWG methodology, the calculated SSTL is 10,000 mg/kg.
(Can you see the uregncy to do ACTION!).

And thanks again!
(Hope we can shake others to investigate any suspected site, before the Authorities come in!).
It's never too late to correct and live in good health for centuries after. (For generations to come, that is!).

 

[oxilume]

Known 100,

Superheated steam stripping the sand/soil works extremely well.

Try this website to give you and coming technologies for treating soil, drill cuttings from drilling rigs, etc. prior to dumping into sea/ocean.

http://www.oxilume.com

Todd

http://www.oxilume.com

 

[layfieldman]

One possibility that you may want to look at is using a geotube. You basically fill up a geotextile tube with the dredged material, add some binding agents or other chemicals to treat the contamination, and the tube contains the sediment inside but allows water to drain out the sides. You must place the tubes inside a bermed area with a liner to contain the released liquid for testing. Once testing is complete the water can be pumped out.

http://www.geotubes.com

is where you can get more information.