rate analysis norms and standard specification

sequence of rate analysis norms for bioengineering works

collection and preparation of seed collection of grass and hardwood cutting for vegetative propagation	collection methods
nursery operation and management (bed preparation) operation and management	nursery
(seed sowing and transplanting; planting hardwood cuttings) preparation of raised materials for extraction from the nursery	nursery
compost and mulch production direct seeding on site planting grass cuttings on site planting shrub and tree seedlings and cuttings on site vegetative palisade construction, brush layering and fascines	bio-engineering
jute netting works fabrication of gabion bolster cylinders	small civil engineering
bamboo tree guards	tree guards

example of specifications given in the 'work description' column

planting rooted grass slips on slopes 45-600 including preparation of slips on site.
operation includes digging planting hole to a max. of 5 cm depth with metal rod or hardwood peg, depending on nature of soil. the planting drills should be spaced 10 cm apart.

standard specification for bioengineering works

2800 2810 2820 2830 2840 2850 2860 2870 2880 2890

provision of seed provision of plant cuttings nursery construction nursery operation and management final slope preparation for bioengineering site planting and sowing jute netting works gabion wire bolsters site protection site aftercare and maintenance

calculation of quantities

s.no.	description of item	no	length	breadth	height	quantity

abstract of cost

s.no.	description of item	unit	unit rate	quantity	amount

estimating and costing

field exercise

in this exercise you will make a quick estimate of work requirements and the costs involved in site works.
working in four groups, you will be assigned a small site near Kurintar, which requires some minor treatment and re-vegetation works. using the Interim rate analysis norms for bioengineering Works you will then carry out the two tasks of estimating and costing.
the exercise consists of:
     a measuring the site;
     b calculating the quantities of materials required;
     c building up the rates;
     d estimating the costs for the site operations.

make a quick estimate of the site dimensions and bioengineering requirements. assume the site has not yet been bio-engineered. keep your proposals simple because there is not much time, but try to introduce a range of techniques to build up a more varied estimate of the site.
use the forms for the calculation of auantities and abstract of costs given on the next pages. these are based on the standard department of roads forms for these purposes.
use the table below for unit rates of a range of operations. note that these are hypothetical rates for this exercise. you may choose any of these techniques for use on your site. if you want to use a technique not included here, make up your own unit rate for the purpose of the exercise. however, do use the interim rate analysis norms for bioengineering Works.

description of item	unit	unit rate
trimming of debris, including cutting, final slope preparation, removal and transport to safe tipping site	m³	500.00
construction of small masonry toe wall, including excavation of foundations and provision of stone, cement, sand, etc.	m³	950.00
broadcasting of grass seeds on slope <40°	m²	5.00
direct seeding with large shrub and tree seeds on site	100 m²	22.00
planting of rooted grass slips (e.g. kans, amliso, babiyo) on 45 to 600 slope at 10 cm centres	m²	16.00
planting of single node culm cuttings of grass on cut slopes >45°	100 nos	125.00
planting of seedlings (e.g. areri) at one metre spacing, including pitting	nos	4.50
planting of cuttings in a brush layer (e.g. simali, asuro)	m	15.50
planting of cuttings in a fascine (e.g. simali)	m	24.00

selection of bioengineering techniques

choice of stabilisation techniques

choosing stabilisation techniques is a complicated process, which is not fully understood. there are many variables, most of which cannot be measured in the field. these notes give a practical analysis to reach an optimum course of action. do not consider this information definitive. aways remember the most important part of the analysis is attention to detail.

erosion processes active on site
first look at the site and its surroundings. there is no such thing as a simple ‘text book’ landslide. each site has a variety of processes at work. you must identify them before you start any remedial work. the site may contain one or more type of erosion such as:
     - surface erosion, such as rilling and gullying;
     - planer slide, on a shallow slip plane parallel to the surface
        (translational landslide);
     - shear failure, on a deep, curved slip plane (rotational failure);
     - slumping of material when very wet, through low particle cohesion;
     - falling of debris due to failure of the supporting material.
secondly, there are both ‘internal’ and ‘external’ factors affecting the site. these include:
    - internal factors: small fault lines causing differential erosion in parts of the site;
                                 small slip planes additional to the main failure mechanism;
                                 seasonal springs within the site;
     - external factors: gullies which may discharge on to the site;
                                   landslides which may supply debris on to the site;
                                   rivers which may undercut the toe.
the next stage involves establishing whether the cycle of erosion has reached a stage at which it can be stabilised. if it has not, leave the site until after the next monsoon and do not carry out any further work at this stage.

initial assessment of treatment needs
if it looks as if stabilisation of the site is feasible, you can continue the process of decision making. a further series of questions given below helps to simplify the problems.

question	action if the answer is yes
is the site very long, steep and in danger of a massive failure below the surface?	use retaining walls to break the slope into smaller, more stable lengths.
is the foot of the slope undermined, threatening the whole slope above?	consider building toe walls.
is there a distinct overhang or are there large boulders supported by a soft, eroding band?	consider building prop walls.
is the slope made up mostly of hard rock, so that planting nursery stock would be impossible?	consider direct seeding as an option.
is the slope rough, covered in loose debris or does it have any locally very steep or overhanging sections, however small?	it must be trimmed.

slope segments
once you have answered these questions, you can move on to a more detailed examination of the slope segments. a slope segment can be defined as a length of slope with a uniform angle and homogeneous material that is likely to erode in a uniform manner. the most straightforward way to approach the choice of stabilisation technique is to split sites into segments of slopes. the assumption is that each segment can be treated using the same technique or techniques. but first, there are two important questions to answer.

question	action if the answer is yes
is the slope segment longer than 15 metres?	there may be a risk of serious surface erosion. therefore some kind of physical scour check should be used, such as wire bolsters.
is the slope made up of poorly drained material, with a relatively high clay content?	there is a danger of shallow slumping. techniques used on this sort of material must be designed to drain rather than accumulate moisture.

guidelines for applying bioengineering techniques
the diagram entitled ‘guidelines for applying bioengineering techniques to all slopes’, is an attempt to define the techniques to be used on different sites. many factors determine the optimum technique or combination of techniques, but only the most important have been included here for the sake of simplicity. the following notes explain the five columns.

slope angle
this is the primary distinction, as it is used to identify the sites which need only mild soil conservation treatment, i.e., those less than 30°. a slope steeper than 45° has seriously steep angle and will present greater erosion problems.

slope length
the length of 15 metres is partly arbitrary but represents a good dividing figure between ‘big’ and ‘small’ sites. slope segments longer than 15 metres are open to greater risks in terms of both gullying and deep-seated failures.

aspect
aspect is the orientation of a site relative to the sun. In fact, this category relates to more than just aspect. it covers the environmental dryness of each individual site. the entire site moisture regime must be considered, although aspect is often the dominant factor in determining the site moisture. other major factors are:
     - altitude;
     - rain shadow effect;
     - topographical location;
     - stoniness;
     - soil moisture holding capacity; and
     - winds and ex-monsoon rains.

material drainage
this column relates to the internal porosity of soils and the likelihood of their reaching saturation and losing cohesion, thereby starting to flow. those materials, which have poor internal drainage, tend to have high content of clay relative to sand and silt in the fine fraction. they tend to be prone to shallow slumping if too much moisture accumulates. stabilisation requires some kind of drainage in addition to protection.

optimal techniques
one or more techniques are given which are known to be successful on general sites of each type. however, the general picture may not cover every case and so this flow chart cannot be considered fully comprehensive. some local variations may be needed, the engineer needs to determine this on site.

guidelines for selection of optimal techniques

slope angle	slope length	aspect	material drainage	optimal technique
start ↓	→	→	→	→
>45°	>15metres	N, NE (NW,E)	good	diagonal grass lines
		S, SW (SE,W)	good	contour grass lines
		N, NE (NW,E)	poor	1 downslope grass lines and strengthened rills or 2 chevron grass lines and strengthened rills
		S, SW (SE,W)	poor	diagonal grass lines
	<15metres	any	good	jute netting and planted grass
		N, NE (NW,E)	poor	1 downslope grass lines or 2 diagonal grass lines
		S,SW (SE,W)	poor	1 jute netting and planted grass or 2 contour grass lines or 3 diagonal grass lines
30—45°	>15metres	any	good	1 horizontal bolster cylinders and tree planting or 2 downslope grass lines and strengthened rills or 3 grass seeding, mulch and wide mesh jute netting
			poor	herringbone bolster cylinders and tree planting
	<15metres	any	good	1 brush layering with woody cutting or 2 contour grass lines or 3 grass seeding, mulch and wide mesh jute netting
			poor	1 diagonal grass lines or 2 herringbone fascines and tree planting or 3 herringbone bolster cylinders and tree planting
<30°	any	any	good	1 contour strips of grass and trees or 2 tree planting
			poor	1 diagonal lines of grass and trees or 2 tree planting
any	any	any rocky material		direct seeding of shrubs or small trees

notes: 'any rocky material' is defined as material into which rooted plants cannot be planted but seeds can be inserted in holes made with a steel bar.
a chevron pattern is like this: <<<<<
a herringbone pattern is like this: ←←←←← (like the bones of a fish)