pilot training course in bioengineering

maintenance of bioengineering system

roads like any other structures are subject to deterioration with time even if materials standards and construction methods are monitored. similarly, bioengineering works also deteriorate with time. deterioration commences as soon as each component of works is completed and is progressive.
deterioration of bioengineering works any cause slope failure, followed by obstruction of traffic or even complete blockage or the road. this leads to costs for road users, social costs resulting form closure and road repair costs. to reduce such indirect and direct costs, maintenance of the bioengineering works is essential.

categories of maintenance tasks
the tasks involved in maintenance can be divided into five groups:
a        protection works:
          e.g. protection of plants and planting sites form grazing, theft of firewood
          and timber, and fire protection works;
b        plant treatment:
          e.g. weeding, mulching, trimming, pruning, grass cutting, thinning
          and training of plants;
c        repair to vegetation structures:
          e.g. repairs to palisades, fascines and brush layering, and turfing
          and vegetation enrichment;
d        repairs to inert structures:
          e.g. repairs to revetment and prop walls, gabion walls, bolsters, jute netting
          and wire netting, and sealing cracks;
e        geophysics:
          e.g. small slope trimming, small slip clearance, cleaning subsoil drain outlets.

frequency of carrying out maintenance activities
maintenance of bioengineering works can be divided into four categories in terms of the frequency with which it is carried out:
a routine maintenance:
           this is carried out continuously, though not necessarily at the same
           location repeatedly;
b         recurrent maintenance:
           this maintenance is required at varying intervals during the year with
           a frequency that depends mostly on the seasons;
c         periodic maintenance:
           periodic maintenance is carried out at longer intervals and is particularly
           related to the replacement of worn out civil engineering structures;
d         emergency maintenance:
           this is needed to deal with emergencies and problems calling for immediate
           action e.g. when the soil slope is threatened.

maintenance programming

this exercise involves devising a maintenance strategy for a site, which has been treated with bioengineering. assume that you have just arrived in this office and have been given the task of undertaking bioengineering site maintenance from now on. you need to plan what you will do on your site for the year starting from when you make the assessment. assume that budgets and targets are no problem.
in this exercise, you will work in a group and spend 1 hour on a thorough site investigation. you will then return to the Training Centre and, after a break, you will have 30 minutes for preparing a presentation of the site and its maintenance requirements. you will be given 5 minutes only for presenting your findings followed by a further 5 minutes in which you should lead a discussion on your proposals.
use the 'Work schedule for bioengineering maintenance works' form to help you in determining your maintenance strategy.
or the presentation, you may like to draw a large version of your maintenance schedule on chart paper. this will be provided back at camp.
the main things to look at on your site are as follows.

site history
     - what is the material?
     - what external factors are, or were, affecting the site?
     - what was the original cause of failure/erosion?
     - what were the actual erosion processes at work in each part of the site?
     - how long ago was it treated?
     - what were the treatments? are there signs of anything, which has failed?
     - what was successful in terms of stabilisation/erosion control?
     - how appropriate were the bioengineering treatments?
     - are the civil structures strong enough? are they too big? could they have
       been reduced and more bioengineering used? if so, how?

site maintenance requirements
     - what needs to be done now? identify any outstanding requirements to
        achieve the best possible bioengineering results.
     - what are the maintenance requirements?
     - what needs to be done urgently?
     - what needs to be done to civil structures?
     - what needs to be done to the vegetation structures?
     - what will need to be done on a routine basis?
     - what recurrent problems are likely to need tackling?

example work schedule for bioengineering maintenance works

s.
n

duration→
activities↓

fiscal year 2055/2056

Shra-wan

Bha-dra

As-win

Kar-tik

Man-gsir

Pou-sh

Ma-hg

Phal-gun

Chai-tra

Bai-shakh

Ue-stha

Asha-dh

protection works from:
a
grazing
b
theft of firewood and timber
c
fire

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====

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====

plant treatment:
a
mulching
b
pruning
c
thinning

====
====

====

vegetation structures:
a
fascines
b
brush layering
c
vegetation enrich-ment

====
====
====

inert structures

====

geophy-sics:
a
slope trimming
b
small slop clearing
c
cleaning subsoil drainage

====
====
====

====

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note: target = ======= progress = ====== emergency works e.g. slope cove = O

seasonal programming of bioengineering activities

activity	throughout year	in dry season	in winter	complete before monsoon
weeding
mulching
trimming
pruning
grass cutting
thinning
slope trimming
small slip clearance
repair of palisade
repair of fascines
repair to brush layering
repair of turfing
vegetation enrichment
cleaning subsoil drain
cleaning surface drain
repair of small engineering system
fire protection
protection of plants, planting sites
protection from grazing and theft of firewood and timber