Final Factual Materials Report

Blue Shield Towers, Hospital Road, Upper Hill. P.O. Box 49712-00100, Nairobi

Tel 020-8013842 Email [email protected] / [email protected] Website www.kenha.co.ke

NATIONAL URBAN TRANSPORT IMPROVEMENT PROJECT

ICB No. KeNHA/ 973/ 2015

REHABLITATION AND CAPACITY ENHANCEMENT

OF

JAMES GICHURU ROAD JUNCTION - RIRONI HIGHWAY (A104)

FACTUAL MATERIALS REPORT

MAY 2015

GENERAL MANAGER (SPECIAL PROJECTS)

KENYA NATIONAL HIGHWAYS AUTHORITY

P.O. BOX 49712-00100

NAIROBI

DIRECTOR GENERAL

KENYA NATIONAL HIGHWAYS AUTHORITY

P.O. BOX 49712-00100

NAIROBI

TABLE OF CONTENTS

Chapter Description Page

1.0 INTRODUCTION ................................................................................................... 1

1.1 Design Standards .................................................................................................. 1

1.2 Location ................................................................................................................. 1

1.3 Topography ........................................................................................................... 1

1.4 Geology ................................................................................................................. 1

1.4.1 Rocks .................................................................................................................... 1

1.4.2 Soils....................................................................................................................... 2

1.5 Climate .................................................................................................................. 2

1.6 Vegetation ............................................................................................................. 2

1.7 Pavement and Existing Road ................................................................................ 2

2.0 SOILS AND MATERIALS SITE INVESTIGATIONS .............................................. 4

2.1 General .................................................................................................................. 4

2.2 Alignment Soil Investigation .................................................................................. 4

2.2.1 General .................................................................................................................. 4

2.2.2 Site Investigations and sampling ........................................................................... 4

2.2.3 Laboratory Testing ................................................................................................ 5

2.2.4 Alignment Soils Test Results ................................................................................. 5

2.2.5 Observations on Alignment Soils Test Results ...................................................... 7

2.3 Natural materials site Investigations .................................................................... 11

2.3.1 General ................................................................................................................ 11

2.3.2 Gravel Sources .................................................................................................... 11

2.3.3 Hard Stone Sources ............................................................................................ 13

2.3.4 Sand Sources ...................................................................................................... 24

2.3.5 Water Sources ..................................................................................................... 24

APPENDICES

APPENDIX A: ALIGNMENT SOILS INVESTIGATION AND TEST RESULTS

APPENDIX B: SUMMARY OF GRAVEL TEST RESULTS

APPENDIX C: SUMMARY OF HARD STONE TEST RESULTS

APPENDIX D: LOCATION PLANS FOR HARD STONE SITES

APPENDIX E: GRAVEL MATERIALS SITES LOGS

APPENDIX F: LOCATION PLANS FOR GRAVEL MATERIAL SITES

APPENDIX G: SUMMARY OF MATERIALS INVESTIGATION

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1.0 INTRODUCTION

ESER Consultants Ltd were commissioned by Kenya National Roads Authority (KeNHA) to undertake Consultancy Services for Feasibility Study, Preliminary Engineering Design, Environmental Impact Assessment, Social Impact Assessment, Detailed Engineering Design and Preparation of Bid Documents for the Rehabilitation and Capacity Enhancement of Road A104 from James Gichuru Road Junction to Rironi (A104/ B3 Junction)

One of the tasks involved in the assignment was evaluation of existing pavement and soils and materials site investigation. The purpose of the materials investigations was to identify suitable and sufficient sources of pavement construction materials along the entire project road.

1.1 Design Standards

The design standards adopted will be those stipulated in the Road Design Manual Part III and the standard specification for construction of Roads and Bridges of Kenya.

1.2 Location

The project road is a section of road A104 road running from James Gichuru Road Junction to Rironi at the junction to the B3 road. The project road runs through a generally rolling terrain.

1.3 Topography

The area lies within an altitude of 1800m to 2550m.

1.4 Geology

1.4.1 Rocks

The project area is part of the volcano-stratigraphy of the KedongKinangop region on the east side of the central Kenya rift. Four principal phases of volcanic eruption were: widespread Kinangop tuff ash flows, Limuru flood trachytes, basalts and flood trachytes of the rift floor, Quaternary salic caldera volcanoes.

The geology of the area is comprised of volcanic layers of basalts, trachytes, phonolites and tuffs all overlain by thick layers of clay soil. Basalts and trachytes form good aquifers whereas tuffs are aquifers only when fractured. Faults delineated from a study of aerial photographs trend in a North-South direction in conformity with the structural pattern of the eastern branch of the Great Rift Valley.

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1.4.2 Soils

The main soil types are black cotton soils and the red soils. The soil drainage characteristics have been classified in accordance with the TRRL classification reproduced in table 1.4 below. These can be classified under well drained

Table 1.4: Soil Permeability Classification

Soil Class Description

Impeded drainage

Very low permeability Clay soils with high swelling potential Shallow soils over largely impermeable layer , very high water table

Slightly impeded Drainage

Low permeability Drainage slightly impeded when soil fully wetted

Well Drained Very permeable Soil with very high infiltration rates such as sands, gravels and aggregated clays

Source: TRRL Laboratory Report 706, Transport and Road Research Laboratory, Department of Environment UK, 1976

1.5 Climate

The area has a moderate climate resulting from its high altitude, temperature ranges from 260C to 100C (lowest).

The area experiences a bi-modal rainfall pattern with the long rains falling between March and May with a mean rainfall of 1300mm while the short rains fall between October and December with a mean rainfall of 1000mm.The mean annual rainfall is 1150mm

1.6 Vegetation

The area is characterized by natural vegetation ranging from moist and dry forest. All types of indigenous trees exist especially near KARI Headquarters and Nairobi School. Some areas around Muguga and Limuru are fully cultivated and the original vegetation has been removed.

1.7 Pavement and Existing Road

The road is a four lanes dual carriageway separated by the median in which the concrete barriers separate both ways from Limuru to Westlands.

There have been major damages of the carriageway with more rutting on the outer climbing lane. Also major patching works have been done in these sections. The rutting, raveling, block cracking, edge breaking, depression and potholes are visible on the entire section, where heavy traffic tend to avoid the outer lane meant to be the slow lane and they are using the inner lane that apparently seem to be less damaged than the outer lane.

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On some sections there has been an overlay with a layer of asphalt concrete that has covered the apparent damages of the surface.

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2.0 SOILS AND MATERIALS SITE INVESTIGATIONS

2.1 General

The purpose of soils and materials investigations was to determine the nature and condition of the alignments soils along the project road and to identify sources within reasonably short haulage distance along the project road where suitable natural construction materials could be acquired for the project. The suitability of the identified materials was to be ascertained by subjecting the materials to the relevant required tests.

2.2 Alignment Soil Investigation

2.2.1 General

The most important characteristic of the sub grade soils is its elastic modulus but its measurement is complicated and time consuming. Since there is always a good correlation between the CBR and the elastic modulus of soils and CBR test is fairly and widely used test, it has been decided to retain it as the quantitative means of evaluating the subgrade bearing strength.

2.2.2 Site Investigations and sampling

Alignment soils investigation was done at 500m interval at varying depth along the road. The sampling done was deemed to represent the entire width including the sections to be extended as stipulated in Sub clause 14.3.1 of the RDM Part III requires that at least one sample shall be taken per kilometer of anticipated alignment. Trial pits were generally excavated to a depth of up to a minimum of 1.0m below the normal ground level. For sections with a median, sampling was done at the middle of the median so as to collect the natural material. Where the New Jersey median exists, sampling was made alternatively left and right at 500m intervals as shown in the section below.

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A representative sample from each trial pit was obtained and taken to laboratory for testing.

2.2.3 Laboratory Testing

The samples taken for laboratory testing were subjected to the following tests:-

Grading to 0.075 mm sieve;

Atterberg Limits (PI, LL, PL and Shrinkage);

CBR 4-Days soak and moulded at 100% OMC

Compaction test (MDD, OMC)

Swelling

2.2.4 Alignment Soils Test Results

The test results of the alignment soils are attached in Appendix A of this report. The summary of the CBRs along the road is shown in Table 2.1 below.

Table 2.1: CBR values of alignment soils

Km 20+932 21+432 21+932 22+432 22+932 23+432

CBR % 6 7 5 10 4 7

Class S2 S2 S2 S3 S1 S2

500m 500m 500m 500m 500m 500m 500m

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Km 23+932 24+432 24+932 25+432 25+932 26+432 26+932 27+432

CBR % 10 11 7 6 5 9 7 8

Class S3 S3 S2 S2 S2 S2 S2 S2

Km 27+932 28+432 28+932 29+432 29+932 30+432 30+932 31+432

CBR % 4 9 6 6 4 8 13 9


Km 31+932 32+432 32+932 33+432 33+932 34+432 34+932 35+432

CBR % 5 5 9 4 5 4 8 3


Km 35+932 36+432 36+932 37+432 37+932 38+432 38+932 39+432

CBR % 4 12 6 8 3 7 12 4


Km 39+932 40+432 40+932 41+432 41+932 42+432 42+932 43+432

CBR % 6 8 6 5 5 11 7 5


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Km 43+932 44+432 44+932 45+432 45+932

CBR % 5 5 8 4 10

Class S2 S2 S2 S1 S3

2.2.5 Observations on Alignment Soils Test Results

Using the Design Manual Part III the following are the CBR values assigned to each subgrade class ranging from S1 to S6. Table 2.2: Subgrade classes

2.2.5.1 CBR distribution

Alignment soils CBR results are shown graphically below.

Class

S1 S2 S3 S4 S5 S6

CBR %

2-5

5-10

7-13

10-18

15-30

>30

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Using the subgrade classes S1 to S6 as shown in Table 2.2 above, the subgrade class in each chainage is assessed.

Table 2.3: CBR distribution table

Subgrade

Class

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Swell at 100% MDD (Standard compaction) and 4 days soak: Less than 2%

Organic matter (percentage by weight): Less than 3% This means no pavement should be placed directly on class S1 soil and that in such a case an improved subgrade is required on such soil.

2.2.5.3 The choice of the design subgrade

Subgrade Class S2 (CBR range 5-10%) makes up approximately 62.7% of the samples tested. However, as noted in Table 2.3 subgrade class above S2 makes a total percentage of about 15.7%. This means that 84.3% of the samples are equal or less than subgrade class S2. The liquid limit (LL) varies from 39 65, with plasticity index ranging from 9 23. The material is fine in grading with percentages passing sieve 75m ranging from 22 98% majority pits indicating values greater than 70%. The plastic modulus of the soil sample ranges from 551-2254.

The alignment soils can be classified as A 7 6 using the AASHTO system of classification and can be rated as poor soils. This is evident from extreme high nature of liquid limit, plasticity index and high filler content passing the 75m sieve. The soils are generally silt and clay and are plastic in nature. For the design purposes it will be prudent to classify the native soils as S2 subgrade as it takes the highest percentage (62.7%).

From alignment distribution the native subgrade class is S2. However the swelling behavior of the alignment soils has also been assessed. It is observed that for the entire road section, the swelling of the soils at 100% MDD (Standard Compaction) and four days soak is less than 2% except the section at chainage 35+432 and 37+932 with a swell of 2.1% and 2% respectively.

However, some of these sections have a CBR at 100% MDD (Standard Compaction) and four days soak which is below 5% hence classified as class S1. Therefore these sections are not suitable for pavement support and will be improved as recommended thereafter. The sections include;

Km 22+932 Km 23+432 Km 27+932 Km 28+432 Km 29+932 Km 30+432 Km 33+432 Km 36+432 Km 37+932 Km 38+432 Km 39+432 Km 39+932 Km 45+432 Km 45+932

All the other sections of the road alignment soils have a CBR of higher or equal to 5% with majority being classified as subgrade class S2, which is within the recommended value. Although from the Roads Design Manual Part III, S2 subgrade material is recommended for the direct support of the pavement, it is proven technically and

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economically advantageous to replace or lay an improved subgrade not only on S1class soils, but also on S2 Class soils. This therefore calls for treatment measures of the soils to take care of the decreased subgrade bearing strength. However it is therefore suitable to minimize the moisture changes and potential swelling in the expansive soils. This will be by use of materials of CBR values of 5% and above especially the top 300mm to provide good support for the pavement structure. The fill materials can be obtained from borrow sites approved by the Engineer.

2.2.5.4 Improved subgrade

Accordingly, there are results indicated in Table 2.3 for the CBR values where the alignment soils are mainly S2 subgrade strength class. Better subgrade should be borrowed from borrow pits to be used as improved subgrade. The improved subgrade will replace the natural soil to obtain a higher class of subgrade bearing strength. Having determined the traffic class to be way above T1, an improved subgrade of class S3 could be attained as shown below.

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Table 2.4: Subgrade improvements

Strength of Native sub-grade soils

Improved subgrade New class of sub-grade achieved Material strength

class Minimum Thickness required

S1 S3 425 S3

S2 S3 300 S3

(Source: RDM part III Table 6.3.1)

Since the analysis of CBR values along the alignment reveals that the subgrade is predominantly S2 with pockets of S1 and S3. The pockets with deleterious material S1 will be removed and will be replaced with materials of class S3 subgrade or higher as localized treatment. Improved subgrade materials will be obtained from borrow pits approved by the Engineer.

2.3 Natural materials site Investigations

2.3.1 General

The purpose of the investigation was to identify sources within reasonably short haulage distance along the project road where suitable natural construction materials could be acquired for the project.

2.3.2 Gravel Sources

Possible sources of gravel whether new or existing were identified. Trial pits were excavated for the gravel sites at grids of 30m and 60m. The pits were dug and sampled to a depth of 1.5m to establish availability of enough material for the construction of the sub base, road base and for use in the embankments. A minimum of 5 trial pits were dug for each of the identified borrow pit and sampled to come up with a reasonable representative sample. A visual inspection and description of each type of material found was done as well as logging of the different strata as detailed in Appendix E. The location of each proposed borrow pit was indicated on a key plan. A site plan of each proposed borrow pit was prepared, showing the means of access and location. In every sampled borrow site, all layers, including top soil and overburden, were accurately described and their thicknesses measured. All layers proposed for use were sampled. The sample was taken over the full depth of the layer proposed, by taking a vertical slice of material.

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The location plans for gravel material sites is included in Appendix F of this report. Representative samples from these borrow sites were subjected to the following laboratory tests.

Grading;

Atterberg Limits (PI, LL, PL and Shrinkage);

CBR 4-Days soak

Compaction (MDD, OMC)

2.3.2.1 Pavement Material Requirement & Results of Tests

Laboratory results on natural materials for base and sub base are contained in Appendix B of this report. The results were analyzed in accordance to the requirements stipulated in charts SB1 and B1 of the MOR$PW Design Manual Part III. These requirements are summarized in the tables below. The results obtained from the above tests were also analyzed to determine whether the materials needed to be improved with cement and lime.

Table 2.4: Natural Gravel Requirements

Requirements Natural Gravel Sub

base

Natural Gravels Road base

Natural gravel-

Cement or Lime

Improved for Sub

base

Natural gravel-

Cement or Lime

Improved for road

base

CBR @ 95% MDD (AASHTO T180), 4 Day Soak

Min. 30 Min. 80 - Min. 20

Plasticity Index Max. 15 Max. 15 Max. 30% Max 25%

Plasticity Modulus Max.250 Max.250 Max. 2,500 Max.2,000

Max. Size -

- 1015 mm 10-50 mm

Passing 0.075 mm Sieve -

- Max 40% Max. 35%

Passing 0.425 mm Sieve

(Lime only) -

- Min. 15% Min. 15%

Plasticity Index (Lime only) - - Min 10 Min 10

Material after treatment: CBR

@ 95% MDD (AASHTO

T180), 7 Day soak 7 day

cure

- -

Min. 60 Min. 160

Source: Charts SB1, SB2, B1, B2 (RDM part III-1987)

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Apart from Maai Mahiu site 1 which qualifies as a source for cement / or lime improved

sub-base, no other materials site satisfies the requirements for pavement construction,

but they could be exploited for improved subgrade material.

2.3.3 Hard Stone Sources

The purpose of the hardstone investigations was to identify suitable and sufficient sources of stones for use in asphalt concrete works, concrete works and or wearing course works. The materials investigation was carried out in the month of July 2012. The identified hardstone sites are discussed below and their photographs and location plans are attached in Appendix D of this report.

2.3.3.1 Borrow and quarry material:

Materials Site CBR @ 95% MDD

(AASHTO T180), 4

Days Soak

Plasticity

Index

Plasticity Modulus

Passing 0.075 mm

Sieve

Passing 0.425 mm

Sieve

Kikuyu 5 21 1659 73% 79%

Nyamu 6 - 14 10 1482 - 1670 55 71% 63 78%

Mutambuki 7 - 8 8 - 18 1482 - 1670 73 82% 82 90%

Maai Mahiu Site 1 9 29 9 - 24 459 - 1771 14 55% 15 70%

Maai Mahiu Site 2 0 2 10 28 187 1420 13 64% 15 - 64%

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NAME OF QUARRY: KIKUYU QUARRY

DESCRIPTION: Hard stone Quarry

DISTANCE FROM MAIN SITE: 1.5 km

GPS POINT N9862786, E240527

OWNER: partly GOK / partly MR. EZEKIEL KURIA GITARU

CONTACT: 0726-015086

This hardstone quarry was first exploited by Federici Impresit Contractors in 1992. The area is approximately 5 acres. The quarry has two major geological characteristics: one half of the quarry extending to the South has red friable clays about 100-500cm deep followed by slightly decomposed friable soft stone (dark brown in colour) extending down to about 20 meters. This material is then followed by decomposed grey tuff (volcanic). This area was excavated and the contractor used this material both for sub-grade layer and improvement of sub-base layer. In some cases, the material was also stabilized and the results obtained were good for sub-base layer.

As the quarry extends northwards, the overburden reduces drastically to about 150cm deep, followed by decomposed grey volcanic tuff stone uniformly to a depth of approximately 20 metres on the average.

The material obtained under this layer is phonolitic trachyte which Federici Impresit Contractors used as their hard stone.

The hard stone was used to construct Westlands - Rironi and also as the aggregate mixer for the finder and wearing course for Rironi-Mai Mahiu Road, the year was 1992-1994.

Since the Contractor had another hardstone just next to Njiru Quarry, most of the hardstone in the quarry was left cleared of the overburden and left unexploited. The local artisans have tried to exploit the stone but they can only manage to cut building stone from the grey tuff, the rest was left undisturbed.

The undisturbed samples were in consideration that this quarry has the stone required for the construction of the project road.

AREA I: The hard stone area is estimated to extend northwards and comfortably over

an area not less than 5 acres.

VEGETATION: The quarry is located in an environmentally friendly area with almost no settlement to the east and to the north. A permanent river is also bordering the quarry. A permanent dam of almost 2 acres is also on the lower side of the border. A Quarry bordering a river will be environmentally acceptable as long as during exploitation, necessary mitigation measures are taken to avoid or minimize pollution of the river and

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the quarry subsequently appropriately rehabilitated and properly drained. These measures have been well detailed in the EIA report section 6.3.1.2 part B4 and B5.

STATUS: The Ministry of Lands office in Kikuyu intimated that this quarry is partly owned by individuals and partly by the government. The government was said to have acquired part of the quarry during construction of Westlands-Rironi road in 1990.

OBSERVATIONS: The stratum of the quarry was interpreted as follows:

1 Red friable clay (coffee soil)

2 Highly decomposed soft stone (brown in colour)

3 Decomposed grey tuff (volcanic)

4 Dark grey phonolitic trachyte hard stone. From other observation, this material goes down to over 100 metres.

TEST REQUIREMENTS: Strata 4

This quarry has therefore been recommended and a sample has been taken for testing by Materials Branch. The following tests are therefore requested: LAA, SSS, ACV, FI, Sieve analysis of fine and course aggregates, specific gravity and Absorption of course aggregate.

TEST REQUIREMENTS: Strata 2

During excavation by the Contractor, both strata i.e. Strata 2 and 3 described separately as highly decomposed soft stone and decomposed grey tuff tend to blend. The resulting material after blending works well for service roads and improvement of access roads to materials sites. The consultant however did not sample this material since access roads are temporary roads whose design and maintenance is the responsibility of the contractor and they are not designed by the consultant neither do they require employers approval.

Various samples were taken from recommended trial pits and homogeneously blended to create a representative sample. The samples were taken to the laboratory and the following tests were requested viz: MDD/OMC, CBR, stabilised and unstabilized grading and PI.

OTHER OBSERVATIONS:

Easily accessible

Environmentally friendly

Has enough area for erection of site offices and crushing machine

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NAME OF QUARRY: MUTARAKWA QUARRY 4 Acres DESCRIPTION: Grey Volcanic Tuff Stone (Soft stone)

DISTANCE FROM MAIN SITE: 3.5 km

GPS POINT N9877037, E234375

OWNER: MR. GATHEE KAMAU: LR 1185 Limuru/Kamirithu

C/o Samuel Njoroge

CONTACT: 0721-789 668 or 0787-623 286

This soft stone quarry was exploited first time by G. Issaias General Contractors about 40 years ago. Since then, so many other contractors have entered and excavated the amount they required, yet the quarry still remains in the hands of the initial title deed holders. We talked to the owners and they are willing to dispose (sell) the required area.

We found the material to be between volcanic grey tuff and phonolite and therefore recommended for some tests to be carried out to find out whether it could be of some use in the construction of James Gichuru-Rironi Roads especially subbase layer and other road stone use. Some samples were taken and the following tests were requested viz: Los Angeles Abrasion (LAA), Aggregate Crushing Value (ACV) and Sieve analysis.

The stratum of the quarry was interpreted as follows:

1 2m deep Red coffee soil

2 1.5m deep Highly decomposed material (brown in colour)

3 Soft tuff (grey in colour) with evidence of possibility of existence Hard stone beneath

OTHER OBSERVATIONS:

Easily accessible



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NAME OF QUARRY: WAIYAKI QUARRY

DESCRIPTION: Area of Hardstone 4 Acres

DISTANCE FROM MAIN SITE: 1 km

OWNER: DR. MUNYUA WAIYAKI & OTHERS

CONTACT: 0733-785801

DESCRIPTION:

The land is sloping and virgin; the material was investigated by JICA in 1993 by drilling, using rotary machine. Stone samples from this quarry were sampled and taken to the laboratory for the necessary tests. On the western lower foot of the quarry, there is also a permanent river and as long as during exploitation, necessary mitigation measures are taken to avoid or minimize pollution of the river and the quarry is appropriately rehabilitated and properly drained it will be environmentally acceptable for exploitation. These measures have been well detailed in the EIA report section 6.3.1.2 part B4 and B5

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NAME OF QUARRY: NYAMU QUARRY 7 Acres

DESCRIPTION: Decomposed friable porous stone

DISTANCE FROM MAIN SITE: 2 km from James Gichuru Road

OWNER: NYORO NYAMU & OTHERS RIRONI

-----------------------------------------------------------------------------------------------------

DESCRIPTION:

The land lies 2 KM west of Rironi-James Gichuru Road on a sloppy ground, but easily accessible on the road to Ndeiya.

Trials were done and the material was found to have too much clay on 1st and 2nd strata. The 3rd strata was found to have highly decomposed friable porous stone, the material found in quarry I with the same characteristic is more superior quality and also other land acquisition logistics are much more comfortable. In conclusion, the quarry was abandoned but some samples were taken just in case more material for subgrade would be required during the time of the road construction.

The site is also environmentally friendly.

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NAME OF QUARRY: KARAI QUARRY 14 Acres

DESCRIPTION: Grey & Volcanic tuff stone

DISTANCE FROM MAIN SITE: Karai - 7 km from Nairobi/Nakuru Road

GPS POINT N9862172, E235372

OWNER:

---------------------------------------------------------------------------------------------------------------------

Accessibility: All weather road from Kikuyu or Kamangu side

Ownership: Privately owned land. Owner ready to dispose for stone excavation.

Material: Material already sampled for testing at the Material branch. Exploited by local artisans, good for subbase and service roads

Vegetation: Stunted wattle back trees.

Overburden: Less than 30cm on average

The Strata was interpreted as follows:

1 1m deep Red coffee soil

2 2m Deep Highly decomposed material (brown in colour)

3 Soft tuff (grey in colour) with evidence of possibility of existence Hard stone beneath

OTHER OBSERVATIONS:

Easily accessible



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NAME OF QUARRY: Bulbul QUARRY in Ngong 7 Acres

DESCRIPTION: Highly Weathered phonolite rock

DISTANCE FROM MAIN SITE: 20 km from James Gichuru Road

OWNER: Ministry of Livestock

-----------------------------------------------------------------------------------------------------

DESCRIPTION:

The land is located in the area south east of Ngong town. Its accessible through all-

weather roads off the tarmac road track to Ngong town. The already acquired area

measures 40acres, and there is room for expansion, and only 15acres has been

exploited.

The ground condition at the site comprises of dark brown to reddish brown top soil

strata of varying thickness from 0.4m to 1m and grading into residual clay soil to

maximum depths of 3.6m below ground level.

Underlying the soil horizon is the highly weathered phonolite rock suite and the highly

weathered horizon consists of Ngong Volcanic rocks of Basanites and Tephrites. Below

the highly weathered rock strata, the degree of weathering reduces from moderate to

slight and into fresh state phonolite in some sections.

The phonolite rock encountered offers suitable road construction material that meets the

material specifications.

The site is also environmentally friendly. The borehole logs, as investigated by the

Ministry of Roads and Material Testing and Research Department for The China Road

and Bridge Corporation (Kenya) is shown in Appendix C.

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The location of each potential source of stone is indicated on a key plan. A site plan of each potential quarry was prepared, showing the characteristic features of the site (including outcrops) and the means of access and location. Six (6) No. hard stone quarries were identified as described above. Investigations carried out Trial holes were dug on a 30 m grid to determine the overburden on each of the selected stone quarries. Five samples were taken per quarry and the position and level of each sampling point was accurately determined and recorded on the site plan, after the quarries have been drilled. Representative samples from these trial pits were taken to Central Testing Laboratories (CTL) located in Nairobi and subjected to the following laboratory tests:-

Los Angeles Abrasion

Aggregate Crushing Value

Sodium Sulphate Soundness

Flakiness Index

Plasticity Index on L.A.A. fines & Plasticity Index on Material passing the 425 micron sieve

Water absorption

Specific Gravity (oven-dry method)

Bitumen Affinity (for stone proposed for use with bitumen).

The results obtained from the above tests, are attached in Appendix C and discussed here below.

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2.3.2.2 Test results

From the Roads design manual part III, for stone to be used in road pavement layers

the requirements shown in the tables below should be achieved.

Table 2.3: Hardstone Quarry Test Results

Materials

Requirement

Los

Angeles

Abrasion

Aggregate

Crushing

Value

Sodium

Sulphate

Soundness

Flakiness

Index

%

passing

0.075mm

Graded Crushed Stone subbase

Max

40%

Max 30% Less than

12%

Max 35% -

Graded Crushed Stone road base

Max

30%

Max 25% Less than

12%

Max 25% -

Lean concrete road base

Max

35%

Max 28% Less than

12%

Max 25% -

Dense Bitumen Macadam road base

Max

35%

Max 28% Less than

12%

Max 25% Max 1%

Asphalt Concrete

Max

30%

Max 25% Less than

12%

Max 20% Max 1%

Surface dressing

Max

20%

Max 16% Max 12% Max 20% -

Concrete works

Max

50%

Max 35% Max 12% Max 35% -

Mutarakwa Quarry

64.3% 27.1% 8.2% 10.2% 0%

Kikuyu Quarry

40.7% 20.3% 8.6% 11.5% 0%

Karai Quarry 47.6% 26.4% 9.5% 13.9% 0%

Bulbul

Quarry

14% 15% 2%

(Source: Chart SB1, SB2, SB3, B1, B2, B4, B6, B7, S1a, S2a MoTC Road Design Manual Part III 1987)

23

Sub-base GCS: From the attached test results, it will be noted that the material suitability for use in subbase is within limits for Kikuyu quarry but not for Karai and Mutarakwa Quarries where the L.A.A exceeds the required value. The percentage of material smaller than 425 micron sieve for all the quarries was between 13% and 16% which is within the stipulated range of between 4-23%. These fines should be non-plastic. Weathered basic rocks like basalt, phonolite and dolerite are of very poor quality since they may contain minerals that are already decomposed and their use should be as limited as possible. L.A.A value exceeds the required maximum value in all the three quarries and therefore they are not suitable to supply material for use in road base. Bulbul quarry is satisfactory on all parameters. GCS Base: L.A.A and ACV values exceed the required maximum value in three quarries except Bulbul quarry and therefore only the latter is suitable to supply material for use in road base GCS. Lean concrete: The material suitability for use in lean concrete for road base fails in all quarries except Bulbul since the L.A.A exceeds the required maximum value of 35%. The percentage of material smaller than 425 micron sieve for all the quarries was between 13% and 16% which is within the stipulated range of between 9-24%.

Dense Bitumen Macadam: All quarries except Bulbul fail on the basis of L.A.A and ACV exceeding the required maximum values. Asphalt Concrete: Kikuyu, Waiyaki and Karura quarries are unsuitable for use in Asphalt Concrete on the basis of L.A.A and/or ACV criteria. Materials from Bulbul quarry are suitable for use. It will be noted that for Waiyaki quarry the LAA was not done because after grading the material did not provide the required quantity of size 14/10 needed to carry out the test. The Consultant found it not necessary to provide extra sample for the test since the material had already failed in other aspects. Surface Dressing: Kikuyu, Waiyaki and Karura quarries are unsuitable for use in surface dressing since in all the L.A.A and ACV exceeds the required value of 20% and 16% respectively. Bulbul quarry material is within limits and material can therefore be used.

Concrete Works: From the tests results, Kikuyu and Karai quarries qualifies for supply of material for concrete works but Mutarakwa quarry fails in L.A.A. In all three quarries, water absorption value exceeds the required value of 2.5%.

If the quarries were further investigated for provision of soft stone and then tested for CBR, PI on LAA fines and PI of materials passing 0.425mm sieve then they could be used to supply soft stone for sub-base if they are found to comply with the following requirements of RDM part III clause 7.2.5:

LAA does not exceed 70%

PI on LAA fines is non-plastic

24

PI of materials passing 0.425mm sieve from the As dug material does not exceed 15% with a plastic modulus of less than 250

CBR at 95% MDD (Modified AASHTO) after 4 days soak is 60% and above.

Since most of the quarries except Bulbul quarry have failed in one way or the other, the following hard stones sources have been identified by the consultant with a recommendation of sampling them during construction stage:

Kedong Quarry: Kedong hardstone quarry is an already existing quarry that has been used on Mai Mahiu-Naivasha road and it is still used as a commercial quarry supplying construction companies in the area. Currently it is supplying the Contractors working on the geothermal power plant in Naivasha among others. It is a basaltic rock that is relatively hard but produces fairly round aggregates suitable for asphalt work. The distance from the quarry to project road is approximately 27 km from Rironi.

Gilgil Stone Quarry: Gilgil hardstone quarry is a privately owned quarry that has been extensively exploited by the contractor who was working on the Naivasha-Lanet road. It is an open quarry, with a basaltic rock that has fairly round aggregates that are good for asphalt works. Since the quarry is government owned, it is the most ideal to exploit for this project. The only challenge would be the distance from the project road that is approximately 90 km from Rironi. This haulage will be a considerable cost.

2.3.4 Sand Sources

No sand sources were identified at the proximity of the project road but it was noted that the commodity being used in that region is normally imported from either Mai Mahiu or Mlolongo region after being deposited in river beds by water during rainy seasons. These mentioned sources however are not permanent and it therefore not possible to map them or give a location because by the time the contractor is going to implement the works, the material might already be exhausted. Although some recharge takes place by heavy rains, the sources get depleted as more sand is harvested, and harvesters will have to move further into the interior. This implies that the contractor may have to use commercial sources in Nairobi (which is normally what contractors do) or send his own lorries to haul it from the river beds in areas where sand harvesting will be taking place then.

2.3.5 Water Sources

Water for construction purposes is available from a dam in an old quarry in Kikuyu. According to the Managing director of Kikuyu water and Sewerage Company, the water impounds an estimated depth of 30m and an area of 2 acres. The dam is located approximately 2km from the project road on the LHS from Kikuyu underpass (GPS POINT: N9862606, E240803). The managing director of Kikuyu water and sewerage indicated that they once carried out a hydrogeological survey of the dam and found the depth of the dam to be approximately 30m. It was also confirmed by the Managing director of Kikuyu Water and Sewerage Company (Eng. Wahinya) that Kikuyu dam has

25

a permanent recharge and it has never dried up. He intimated that two individuals own the dam and for one to draw water from the dam he has to consult these individuals. One of the individual is known as Mr. Kinyuru (Msafiri). At the time of Consultants visit, it was observed that there is a permanent outflow indicating that recharge is greater than outflow. This dries up only during extreme drought period.

Water can also be obtained from a dam in Limuru known as Manguo (GPS POINT: N9877652, E2236779) which is about 2km from A104/B3 junction towards Limuru and another one in Karai known as Karai dam which is 7km from A104/B3 junction on the LHS from Kamandura. Manguo dam was reported by Limuru water and Sewerage Company to have water throughout the year unless also there is a drought.

27

APPENDICES

28

APPENDIX A:

ALIGNMENT SOILS INVESTIGATION AND TEST RESULTS

29

Sample No. 001 002 003 004 005 006 007 008 009

Chainage 20+932 21+432 21+932 22+432 22+932 23+432 23+932 24+432 24+932

Offset CENTRE RHS LHS CENTRE RHS LHS CENTRE RHS LHS

Liquid Limit % 57 48 47 48 54 50 39 48 47

Plasticity Index % 15 14 14 14 17 16 17 13 11

Passing B.S.S No. 75mm %


Passing B.S.S No. 50mm % 100 100 100

Passing B.S.S No. 37.5mm % 98 97 90 100

Passing B.S.S No. 28mm % 100 98 96 87 97

Passing B.S.S No. 20mm % 96 94 93 80 97

Passing B.S.S No. 14mm % 92 93 88 78 97

Passing B.S.S No. 10mm % 91 100 92 86 75 100 97

Passing B.S.S No. 6.3mm % 87 99 91 84 71 99 96

Passing B.S.S No. 5mm % 85 97 90 82 69 99 96

Passing B.S.S No. 4mm % 84 96 89 100 81 67 98 95

Passing B.S.S No. 2mm % 100 79 89 87 98 78 63 97 94

Passing B.S.S No. 1mm % 99 75 83 85 96 73 63 96 90

Passing B.S.S No. 0.6mm % 99 73 79 82 95 67 59 95 86

Passing B.S.S No. 0.5mm % 98 72 78 81 94 66 56 95 84

Passing B.S.S No. 0.425mm % 98 72 77 80 93 65 55 94 81

Passing B.S.S No. 0.3mm % 97 71 76 79 93 63 54 93 75

Passing B.S.S No.0.15mm % 97 70 75 78 92 62 53 93 70

Passing B.S.S No. 0.075mm % 97 70 75 78 92 62 50 93 69

M.D.D (Kg/m3) 1220 1350 1330 1320 1200 1380 1440 1490 1270

O.M.C % 26.2 16.5 24.5 21.5 20.0 29.0 15.5 26.4 21.0

CBR at 100% MDD 4 days soak % 6 7 5 10 4 7 10 11 7

swell at 4 days soak % 1.0 0.5 1.1 0.3 0.9 1.0 1.0 0.3 0.6

30

Sample No. 010 011 012 013 014 015 016 017 018

Chainage 25+432 25+932 26+432 26+932 27+432 27+932 28+432 28+932 29+432

Offset CENTRE RHS LHS CENTRE RHS LHS CENTRE RHS LHS

Liquid Limit % 54 58 41 52 54 52 45 54 49




Passing B.S.S No. 50mm % 100

Passing B.S.S No. 37.5mm % 100 94

Passing B.S.S No. 28mm % 100 96 91 100

Passing B.S.S No. 20mm % 100 97 96 84 99

Passing B.S.S No. 14mm % 99 95 96 100 81 99

Passing B.S.S No. 10mm % 99 94 95 99 80 99

Passing B.S.S No. 6.3mm % 99 90 94 99 78 99

Passing B.S.S No. 5mm % 99 89 94 99 77 99 100

Passing B.S.S No. 4mm % 98 88 94 98 76 99 99

Passing B.S.S No. 2mm % 98 84 93 100 98 73 98 99

Passing B.S.S No. 1mm % 100 97 79 91 99 97 71 97 99

Passing B.S.S No. 0.6mm % 99 73 72 91 98 95 68 96 98

Passing B.S.S No. 0.5mm % 99 72 70 90 98 95 67 95 98

Passing B.S.S No. 0.425mm % 99 71 69 90 98 94 66 95 98

Passing B.S.S No. 0.3mm % 98 70 67 89 98 92 65 93 98

Passing B.S.S No.0.15mm % 98 69 66 89 97 88 65 92 97

Passing B.S.S No. 0.075mm % 98 69 60 89 97 88 65 92 97

M.D.D (Kg/m3) 1080 1220 1450 1180 1420 1120 1400 1140 1170

O.M.C % 29.2 29.4 28.0 27.7 25.0 19.8 21.2 29.0 25.0



31

Sample No. 019 020 021 022 023 024 025 026 027

Chainage 29+932 30+432 30+932 31+432 31+932 32+432 32+932 33+432 33+932

Offset RHS LHS RHS LHS RHS LHS RHS LHS RHS

Liquid Limit % 56 53 46 49 53 48 57 50 53




Passing B.S.S No. 50mm % 89 100

Passing B.S.S No. 37.5mm % 84 98 100

Passing B.S.S No. 28mm % 83 100 94 95

Passing B.S.S No. 20mm % 80 94 93 93

Passing B.S.S No. 14mm % 78 92 93 100 88

Passing B.S.S No. 10mm % 76 87 91 98 88

Passing B.S.S No. 6.3mm % 73 83 90 94 88

Passing B.S.S No. 5mm % 71 80 89 89 87

Passing B.S.S No. 4mm % 100 69 78 100 88 85 87 100

Passing B.S.S No. 2mm % 99 64 71 99 86 64 86 99

Passing B.S.S No. 1mm % 100 98 61 67 97 84 46 86 98

Passing B.S.S No. 0.6mm % 99 97 58 65 93 82 35 84 95

Passing B.S.S No. 0.5mm % 99 96 57 65 90 81 33 83 93

Passing B.S.S No. 0.425mm % 98 95 56 64 86 80 29 81 91

Passing B.S.S No. 0.3mm % 98 93 54 62 81 78 25 80 86

Passing B.S.S No.0.15mm % 98 90 54 61 78 75 22 76 85

Passing B.S.S No. 0.075mm % 98 90 54 61 77 75 22 76 84

M.D.D (Kg/m3) 1210 1290 1320 1450 1310 1240 1400 1220 1150

O.M.C % 25.9 26.3 23.0 20.8 27.2 28.0 27.8 26.2 24.0



32

Sample No. 028 029 030 031 032 033 034 035 036

Chainage 34+432 34+932 35+432 35+932 36+432 36+932 37+432 37+932 38+432

Offset LHS RHS LHS RHS LHS RHS LHS RHS LHS

Liquid Limit % 50 39 51 52 48 46 51 48 65





Passing B.S.S No. 37.5mm % 100

Passing B.S.S No. 28mm % 96 100 100 100

Passing B.S.S No. 20mm % 94 99 97 99

Passing B.S.S No. 14mm % 93 99 94 99

Passing B.S.S No. 10mm % 92 99 93 99

Passing B.S.S No. 6.3mm % 100 91 99 100 92 100 99

Passing B.S.S No. 5mm % 99 91 98 99 91 99 99

Passing B.S.S No. 4mm % 98 91 98 99 91 99 99 100

Passing B.S.S No. 2mm % 95 89 98 96 88 98 98 99 100

Passing B.S.S No. 1mm % 93 89 96 93 86 97 98 97 99

Passing B.S.S No. 0.6mm % 92 88 94 89 83 96 95 96 99

Passing B.S.S No. 0.5mm % 91 88 93 88 82 95 95 96 98

Passing B.S.S No. 0.425mm % 91 87 92 86 79 92 94 95 98

Passing B.S.S No. 0.3mm % 90 86 90 82 76 92 94 94 96

Passing B.S.S No.0.15mm % 90 85 88 80 71 90 94 94 96

Passing B.S.S No. 0.075mm % 90 85 88 80 71 90 93 94 95

M.D.D (Kg/m3) 1190 1470 1070 1240 1410 1400 1350 1090 1260

O.M.C % 22.6 23.2 25.7 25.0 23.9 27.0 28.1 26.5 34.2



33

Sample No. 037 038 039 040 041 042 043 044 045

Chainage 38+932 39+432 39+932 40+432 40+932 41+432 41+932 42+432 42+932

Offset RHS LHS RHS LHS RHS LHS RHS LHS RHS

Liquid Limit % 53 44 46 49 45 54 47 44 47










Passing B.S.S No. 6.3mm % 88 92

Passing B.S.S No. 5mm % 87 100 91

Passing B.S.S No. 4mm % 86 100 99 100 100 100 100 91

Passing B.S.S No. 2mm % 81 99 98 98 100 97 96 99 87

Passing B.S.S No. 1mm % 77 98 94 94 99 95 92 98 84

Passing B.S.S No. 0.6mm % 73 96 90 90 98 93 86 96 81

Passing B.S.S No. 0.5mm % 72 96 88 89 97 93 82 96 81

Passing B.S.S No. 0.425mm % 71 95 85 88 97 92 77 95 79

Passing B.S.S No. 0.3mm % 68 93 80 87 95 90 73 94 77

Passing B.S.S No.0.15mm % 64 91 79 87 94 85 71 91 77

Passing B.S.S No. 0.075mm % 63 91 79 87 94 85 63 91 76

M.D.D (Kg/m3) 1430 1280 1370 1130 1410 1260 1220 1220 1460

O.M.C % 25.4 30.5 25.0 24.3 30.0 23.5 26.6 22.5 28.5



34

Sample No. 046 047 048 049 050 051

Chainage 43+432 43+932 44+432 44+932 45+432 45+932

Offset LHS RHS LHS CENTRE RHS LHS

Liquid Limit % 44 49 49 52 35 68

Plasticity Index % 10 14 14 17 22 18








Passing B.S.S No. 10mm % 87 99 98 100 100

Passing B.S.S No. 6.3mm % 84 98 98 99 97

Passing B.S.S No. 5mm % 83 98 98 99 97

Passing B.S.S No. 4mm % 82 98 98 99 100 95

Passing B.S.S No. 2mm % 78 95 95 95 99 93

Passing B.S.S No. 1mm % 76 93 94 92 99 91

Passing B.S.S No. 0.6mm % 72 89 92 90 98 90

Passing B.S.S No. 0.5mm % 71 88 92 90 98 88

Passing B.S.S No. 0.425mm % 70 83 91 90 97 88

Passing B.S.S No. 0.3mm % 69 83 90 90 97 83

Passing B.S.S No.0.15mm % 68 81 88 89 97 80

Passing B.S.S No. 0.075mm % 68 81 88 89 97 80

M.D.D (Kg/m3) 1090 1390 1280 1390 1160 1360

O.M.C % 19.0 28.2 26.5 29.8 35.0 28.5

CBR at 100% MDD 4 days soak % 7 5 5 8 4 10

swell at 4 days soak % 0.8 0.9 1.4 1.0 1.0 0.8

35

APPENDIX B:

SUMMARY OF GRAVEL TEST RESULTS

40

Bulbul Quarry Site

41

APPENDIX C:

SUMMARY OF HARD STONE TEST RESULTS

44

Bulbul Quarry

Materials property Test Results

Los Angeles Abrasion 14%

Aggregate Crushing Value 15%

Sodium Sulphate Soundness 2%

45

APPENDIX D:

LOCATION PLANS FOR HARD STONE SITES

46

Mutarakwa quarry 4Km on left from A104 along road B3. Possible source of

hardstone and crushed Stone.

Kikuyu quarry located 2Km on left from road A104 at Kikuyu underpass. Possible

source of gravel, hardstone and soft stone.

47

1.

Waiyaki Quarry 340m on left from road A104 at Kinoo on the left. Possible source

of gravel, hardstone and crushed Stone. Note the overgrown vegetation due to

recent rainy season.

Kamuguga Quarry 200m on right from road A104 at Muguga. Possible source of

hardstone and crushed stone. Note settlement at the background and therefore

quarry not recommended for exploitation.

48

2.

3.

Karai quarry 7Km on left from A104 at Kikuyu underpass. Possible source of

hardstone and crushed Stone.

Southern access road connecting Kikuyu quarry, the Old Quarry and then to A104 (Aprox. 2km). The

49

To Nakuru

Kikuyu Quarry Estimated quantity= 500,000m3

Kikuyu Junction

Underpass

From Nairobi

Rear access 1.5km long

Sketch showing access to Kikuyu Quarry from the project road

Roa

d A

104

Front access 2km long

50

To Nakuru

Waiyaki Quarry Estimated quantity= 500,000m3

Kikuyu Junction

Underpass

Access 1.0km long

Sketch showing access to Waiyaki quarry from the project road

Roa

d A

104

From Nairobi

Kinoo

51

To Nakuru

Mutarakwa Quarry Estimated quantity= 80,000 m3

A104/B3 Junction

From Nairobi

Road B3

Sketch showing access to Mutarakwa Quarry from the project road

Roa

d A

104

Access 3.5 Km from A104/B3

Junction

52

To Nakuru

A104/B3 Junction at

Kamandura

Sketch showing access to Karai quarry from the project road

From Nairobi

Road B3

53

Bulbul Quarry Location: 1 20 01.11 South, 36 39 33.13 East

Bulbul Quarry Site

Underlying the soil horizon is the highly weathered phonolite rock suite and the highly weathered horizon consists of Ngong Volcanic rocks of Basanites and Tephrites. Below the highly weathered rock strata, the degree of weathering reduces from moderate to slight and into fresh state phonolite in some sections.

Bulbul Quarry is an existing quarry that is currently being used on the construction of Southern Bypass. It is a large quarry with a face of approximately 12 m high, and a length of 200m. The quarry can be easily extended to approximately 100m going inside the land. The overburden varies and can be as high as 2 m at some areas.

54

Bulbul quarry has a reserve of more than 2,000,000 cubic meters of hard stones that can be

exploited during construction.

Quarry under exploitation for the construction of Southern Bypass Road.

Investigations carried out

Trial holes were dug on a 30 m grid to determine the overburden on each of the selected stone quarries.

Five samples were taken per quarry and the position and level of each sampling point was accurately determined and recorded on the site plan, after the quarries have been drilled. Representative samples from these trial pits were taken to Central Testing Laboratories (CTL) located in Nairobi and subjected to the following laboratory tests:-

Los Angeles Abrasion

Aggregate Crushing Value

Sodium Sulphate Soundness

Flakiness Index

Plasticity Index on L.A.A. fines & Plasticity Index on Material passing the 425 micron sieve

Water absorption

Specific Gravity (oven-dry method)

Bitumen Affinity (for stone proposed for use with bitumen).

69

APPENDIX E:

GRAVEL MATERIALS SITES LOGS

70

Kikuyu Borrow pit log

1 60cm Red friable clay (coffee soil)

2 10m Highly decomposed soft stone (brown in colour)

3 1.5m Decomposed grey tuff (volcanic)

4 Dark grey phonolitic trachyte hard stone. From other observation, this material goes down to over 100 metres.

Nyamu Borrow pit log

1 30cm Red friable clay (Red coffee soil)

2 75cm Highly decomposed soft stone (brown in colour)

3 Reddish gravel

Mutambuki Borrow pit log



3 Reddish gravel

71

Mai Mahiu 1 Borrow pit log



3

530cm Reddish Brown Gravel

Mai Mahiu 2 Borrow pit log



3 190cm Reddish Brown Gravel

73

APPENDIX F:

LOCATION PLANS FOR GRAVEL MATERIAL SITES

74

Nyamu quarry 3km on LHS from A104 at Rironi. Possible source of gravel

material.

Mutambuki quarry 100m on RHS from A104 at Limuru. Possible source of gravel

material.

75

Trial pits excavation at Kikuyu Quarry

Exploited section of Kikuyu quarry. Disturbed material available could be used

for diversions and improvement of the access road to quarry and service roads.

76

Maai Mahiu Site 1

Maai Mahiu Site 2

77

To Nakuru

Kikuyu Quarry Estimated quantity= 70,000m3

Kikuyu Junction

Underpass

From Nairobi

Rear access 1.5km long

Sketch showing access to Kikuyu Quarry from the project road and

Borrow pit plan

R

oa

d A

104

Front access 2km long

Tp1 Tp2

Tp4 Tp5

Tp6

Disturb

Dumped material

Virgin Virgin

Borrow pit plan showing Trial pits

Tp3

GPS POINT N9862786,

E240527

78

To Nakuru

Nyamu Borrow Pit Estimated quantity=300,000m3

Muguga Junction

Underpass

From Nairobi

Sketch showing access to Nyamu Borrow pit from the project road and

Borrow pit plan

Access 2km long

Roa

d A

104

Borrow pit plan showing Trial pits

Tp1 Tp2

Tp3

Tp4

Tp6

Tp5

79

To Nakuru

To Mai Mahiu

Mutambuki Borrow Pit Estimated quantity= 200,000m3

From Nairobi

Sketch showing access to Mutambuki borrow pit from the project road

81

ROAD 104

To

M

AI

-

M

A

HI

U

Proposed Extension

Overburden Area Investigated

Material Depth

Estimated Quantity

m 0.5 182.75Sq. m

m 5.3

,968,000 Cu m 2

Top Soil m 0.1

19

K

m

PROJECT: ROAD A104/JAMES GICHURU JUNCTION - RIRONI/B3 JUNCTION

Key Test Pit

Access Road

Main Road

Estimated Extent of the Borrow Pit

P1

P2

P3

P4

Exploited Area

Note:

Grid spacing = 60m through out

11

1

m

m 18

m 25

m 80

0

700 m

m 700

R

O

A

D

B

3

GRAVEL MATERIAL BORROW SITE (MAI-MAHIU BORROW PIT NO. 1)

TO NAKURU

ROAD TO MAI-MAHIU

19km from Project Road

82

ROAD A104

To

M

AI

-

M

A

HI

U

Proposed Extension

Overburden Area Investigated

Material Depth

Estimated Quantity

0.5 m 1200 Sq. m

m 1.9 480 , 000 Cu m

Top Soil 0.1 m

15

K

m

Key

Test Pit

Access Road

Main Road

Estimated Extent of the Borrow Pit

P1 P4

P2 P3

Exploited Area

Note: Grid spacing = 60m

24

m

14 m

10 m

m 300

m 500

B

2

ROAD TO MAAI MAHIU

200 m

50

0

m

PROJECT: ROAD A104/JAMES GICHURU JUNCTION - RIRONI/B3 JUNCTION

GRAVEL MATERIAL BORROW SITE (MAI-MAHIU BORROW PIT NO. 2)

15km from Project Road

83

APPENDIX G:

SUMMARY OF MATERIALS INVESTIGATION

84

Summary of material sites investigated

Quarry/ Borrow pit Material Findings Conclusion

Kikuyu Quarry Hardstone Quarry qualifies for:

- GCS for use in road

subbase.

-Aggregates for

concrete works

Material can be

exploited for use

Mutarakwa Quarry Hardstone The stone fails in

L.A.A and ACV

Not suitable for

exploitation

Karai Quarry Hardstone Quarry has suitable

aggregates for

concrete works

Material can be

exploited for use

Karura Quarry Hardstone The stone fails in

L.A.A and ACV

Not suitable for

exploitation

Waiyaki Quarry Hardstone The stone fails in

L.A.A and ACV

Not suitable for

exploitation

Bulbul Quarry Hardstone Meets requirements

for all GCS, asphaltic

mixes, surface

dressing and concrete

works

Suitable for all

pavement layers

Kikuyu borrow pit Gravel Gravel has low CBR Material can be

used to improve

subgrade

Mutambuki borrow

pit

Gravel Gravel has low CBR Material can be

used to improve

subgrade

Nyamu borrow pit Gravel Gravel has low CBR Material can be

used to improve

subgrade

Maai Mahiu 1 Gravel Meets requirements

for cement and lime

improved sub-base

Material can be

used to improve

sub-base

Maai Mahiu 2 Gravel Low CBR Not suitable for

exploitation