Abstract
There are various methods available for treating the runoff water from peat
mining, and this research concentrates on measures applied within the peat
production areas themselves. The work is divided into three sections: comparison
of sod peat and milled peat production, development of a new subsurface drainage
method and the use of barriers constructed of wood chips to equalize peak
runoffs.
The research into peat mining methods was carried out by comparing similar
production areas over a period of four years. The methods did not appear to have
any effect on the mean runoff, but the peak runoffs from sod peat production
were smaller than from milled peat production. The furrows made by the sod peat
machine seemed to equalize the peak runoffs and at best reduced their value by
25 millimetres. The increase of mean phosphorus content resulting from milled
peat production was statistically significant, and the peak solids content was
higher, but the production method did not appear to affect other mean
concentrations significantly.
A new subsurface drainage method that uses rock fibre boards as vertical
water
conductors was developed. These were used to lead rain water and meltwater from
snow away from the production areas to the subsurface pipes so that no surface
water entered the collector ditches serving the production area. The method was
tested in two production areas over a period of six years.
Subsurface drainage proved to be an efficient method, and the vertical water
conductors eliminated problems arising from the poor water conductivity of peat
and the presence of ground frost. Natural peatlands require pre-drying before
subsurface drains can be constructed, however. Subsurface drainage is better
able to equalize runoffs than open ditches, so that no high peak runoffs occur
in properly planned production fields. Also, subsurface drainage reduces solids,
COD and the colour by comparison with open ditches, but increases the iron
content. The results regarding phosphorus and nitrogen vary a great deal and no
clear difference could be detected. Concentrations in the areas where subsurface
drainage was used varied very little and no peak concentrations similar to those
in areas with open ditches were detected. This together with the uniform runoffs
substantially reduces stress to the environment.
The feasibility of using barriers constructed of wood chips in bed
ditches and
in peat redistribution areas was also investigated. The barriers worked well in
the peat redistribution areas and the research is being continued with attempts
to improve the functioning of the structures. The use of these barriers in bed
ditches proved too laborious.
| Identifer | oai:union.ndltd.org:oulo.fi/oai:oulu.fi:isbn951-42-5835-5 |
| Date | 04 December 2000 |
| Creators | Röpelinen, J. (Jyrki) |
| Publisher | University of Oulu |
| Source Sets | University of Oulu |
| Language | Finnish |
| Detected Language | English |
| Type | info:eu-repo/semantics/doctoralThesis, info:eu-repo/semantics/publishedVersion |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess, © University of Oulu, 2000 |
| Relation | info:eu-repo/semantics/altIdentifier/pissn/0355-3213, info:eu-repo/semantics/altIdentifier/eissn/1796-2226 |
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