1. Situation of the Kalimok-Brashlen Marshes	1 copy
2. Graphics of Experimental Water-Infusion.	5 p.
3.Engineering-Geological Block-Diagram M 1:10000/2000	1 copy
4. Graphics of Dynamic Penetrations of a Light Type	23 p.
5. Graphics of Geophysical Experiments with the WES Method	4 p.
6. Geotechnical Columns of Exploratory Borings	20 p.

1. Introduction

During the period May - July 2003 there was conducted a hydrogeological and geotechnological piece of research of the sites “Kalimok-Brashlen Marshes” including the implementation of geological-research-works pursuant to the requirements of the technical task. For the site, there were implemented: 5 tests for water-infusion /each test was implemented with the usage of two different methods/, 15 exploratory borings, 23 dynamic penetrations of a light type and 3 geophysical research with the WES method. From the site there were taken and given for analysis 5 inviolate earth samples, the results of which will be delivered later on. The location of all geological work out was defined with the help of a GPS apparatus and drawn on the large-scale maps elaborated for this purpose.

2. Hydrogeological research.

Hydrogeological research of the humid zone of Kalimok/Brashlen Marshes.

It is located between the villages of Marten and Brashlyan in a strip with a length of 50 km and a total area of 200-250 km². It is an alluvial valley consisting of three river terraces (low inlet one and two over-inlet ones) with an above-sea level from 14-15 to 28-30m. The total thickness of the alluvial sediments varies from 2-3 m to the west and 17-18 m to the east and on the average - 8-9 m.

Besides the porous water-carrying horizon in alluvial types of gravel and sand in the low Danube terrace, there also exists a Karst water-carrying horizon in the limestone of Barem.

The Karst water-carrying horizon (thickness of about 150-200 m) is fed up by a vast area to the south of the region of research. The underground flow is oriented to the north and drains in the alluvial types of gravel of the low terrace of the river Danube and through them - directly into the river. The conductivity of the Karst water-carrying horizon is 800-1000 m³/d (obtained from the data of exploratory water-drawings). The natural underground flow in the stratum (at a unit width of the flow - 1 m) has been measured earlier on the basis of the existing piezometrical maps and amounts to 8 m³/d or about 90 l/sec. km.

The Alb marls are water-support. They constitute the pad of the alluvial terrace in the central part of the region. The other part of this pad is occupied by the limestones of Barem.

The Quaternary water-carrying horizon in the alluvial terrace is fed up by the Karst water-carrying horizon (from south) all year long. The river is its north border. There is also a direct hydraulic bond with a two-way exchange. In cases of high levels in the river the water-carrying horizon is fed up by the river, in cases of low levels in the river - the flow is reverse. The level of underground waters varies all permanently; the depth is usually between 0.5 and 3 m under the earth surface (it is due to the draining canal system). The alluvial types of gravel and sand are covered almost everywhere with sandy clays. This is a poorly permeable layer which plays an important role for the future humid area.

2.1. Experimental Water-Infusion.

Filtration tests for defining of the coefficient of filtration of the dust-sandy clays over the water-carrying horizon (the aeration zone).

Scope of experimental-filtration research.

The coefficient of filtration of the clays constituting the aeration over the water-carrying horizon of the alluvial types of gravel is defined at two levels:

· Level 1 - including a layer with a depth of 0.4 - 0.5 m. under the terrain. i.e. the layer lying just under the bottom of the future lake;

· Level 2 - including the deeper part of the aeration zone (between 0.5 and 2 meters under the terrain) during which mainly the infiltrated from the lake water will flow to the water-carrying horizon.

We shall notice that it was not possible (neither necessary) to conduct deeper tests in the aeration zone as the level of underground waters during the research period was quite high - at some places it was by 2.5 - 3 m. under the terrain.

Methods of taking and interpretation of the filtration tests.

The relatively low water-permeability of the clay sediments predetermined as most suitable the express water-infusions.

a. Shallow tests (Level 1).

At first express water-infusions in “SHURFI” (rings) were planned. However, the tests were conducted according to a scheme which differs from the water-infusions in the standard rings. In the dug shallow “SHURFI” a pipe with a small diameter (85mm.) was stuck in which the fast water-infusion was conducted and the resulting lowering of the level was followed up. Actually, this test corresponds to the scheme “water-infusion through boring working with his bottom only”. For this reason, jointly with the consultant, in order to define the coefficient of filtration respective methods which are adequate to these tests were applied.

The defining of the coefficient of filtration according to the data from similar tests is treated in the works of Kirkham [1946], Joungs [1968], Mironenko & Shestakov [1978] and other. Over the abscissa axis the values of time (t) are drawn up from the beginning of the test (the instant infusion) and over the ordinate axis in a logarithmic scale - the remaining water column (H) at the respective moment - Fig...1. The slant of the obtained representative straight line (I) is defined after which the coefficient of filtration is calculated with the help of the formula:

k = 1040 r I,

where r is the boring’s radius in m.; i is the slant of the straight line in min^-1. The coefficient of filtration is in m/d.

H₀

t₁

t₂

lgH₂

lgH₁

Figure 1

b. “Deep” tests (Level 2).

In this kind of tests the boring “operates” with all it’s open trunk. The data processing is conducted according to a procedure famous in the literature as “Method of Ernst” (here it is presented with an insignificant modification). The data about the lowering of the level are drawn up in the co-ordinates

lg(s+0.5r) = f(t). I.e. along the abscissa, the time t is drawn up and along the ordinate the respective values of the expression (s + 0.5r ) - Fig.2. The result is a straight line with a slant i. Having defined the slant of the representative straight line, the coefficient of filtration k can be calculated according to the formula

k = 16.5 r i

where the boring’s radius r is in cm, and the slant of the straight line - in min^-1. Yet, the coefficient of filtration is in m/d.

We have to notice that the initial moments deviate from the representative straight line in an ordinary way as the latter corresponds to the approximate solution of the problem which becomes valid some time after the beginning.

S_o

t₁

Figure 2

Results from the calculations.

2.1.1. Exploratory water-infusions

On the site, in compliance with the technical task, there were implemented by 5 water-infusions for the first and second level.

The results of the filtration tests processed according in concordance wit the described above methods are presented in Appendices II.2., and in Table 2 the obtained coefficients of filtration are shown.

Express water-infusions in borings - values of the coefficient of filtration

Table 2

	Lot				K_mid
Level 1	Point B	Point C	Point E	Point F
	0.026	0.112	0.011	0.292	0.110 m/d
	Lot				K_mid
Level 2	Point B	Point C	Point E	Point F
	0.102	0.197	0.109	0.162	0.142 m/d

The shallow layer (up to 0.5 m) is relatively non-homogeneous but as a whole - with a not so high coefficient of filtration. Its mean is

k » 0.11 m/d.

Under it, the clays from the aeration zone differ with exceptional homogeneity from a filtration viewpoint. The received in the four lots (too far from each other) values for the coefficient of filtration are located in the narrow interval between 0.1 and 0.2 m/d (!). Therefore, for the clays from the aeration zone we can quite confidently accept a mean coefficient of filtration

k » 0.14 m/d.

The boring in lot 1 makes a significant exception, as the filtration characteristics of the tested layer are much higher that the rest. It is obvious from the test itself which has terminated for 3-4 minutes only while for all other borings this time is between 20 and 40 minutes. The results from this test are given in Appendix II.2. and an approximate value of k = 4.83 m/d is obtained from them. It is obvious that here the boring has not passed through clays but through fine-grained sands.

3. Geotechnical research.

In compliance with the technical task, geotechnical research were conducted about:

1. The road-bed of the internal drainage canal, around the wetland area, parallel to the border dikes with a length of about 15 432 m and a width of 100 m. For the drawing up of a technical report for the needs of projecting there were implemented 17 borings with depths depending on the dikes and 17 dynamic penetrations of a light type according to the Bulgarian State Standards, with a depth up to 4 m.

2. The entrance Points B (rkm 448) and C (rkm 442) E, exit Point E (rkm 436.0), the entrance canals in Points B and C (rkm 449) - an approximate length of 500 m and the existing exit canal in Point B and the existing exit canal in Point E (436.0). For the drawing up of a technical report for the needs of projecting there were implemented 3 borings, 6 dynamic penetrations and 3 research with the help of the BEC method.

From the research conducted it was found that the earth basis consists of:

Quaternary-alluvium Qal

Layer 1. - Clay, brown, dust-sandy to sandy. This layer is the basic covering water-impermeable layer of the territory under research. Its power is 12-16 m, but at certain places /point 1, around BH 8/ it is absent. The upper 50-80 cm of the layer are covered with soil. In the location of this layer 16 dynamic penetrations are conducted, with a depth up to 4 m, as in it the main capacity of earth works will be done. In compliance with it for this layer there are defined:

- volume density - 1,8 g/cm³

- coefficient of pores - 0,8-1,1

- compression module for a vertical load 0,2-0,3 MPa M=up to 6,5 MPa.

- module of general deformation Eo=0 to 23 MPa /see Appendix B.II.4./

- calculation angle of internal friction -10°

- calculation cohesion - 0.05 MPa

- calculation loading Ro - depending on the results from the penetrations for each separate case /see Appendix B.II.4/

- category of ditch - earth

Layer 2. - Sand, grey, with various grains, to dust clay sand. This layer usually occurs under the clays and over the gravels. For this layer we accept:

- volume density - 1,65-1,75 g/cm³

- category of ditch - earth

Layer 5. Gravel, with various grains, with sandy aggregate, co MPact. It occurs in the low parts of the alluvial complex. The power of this layer has not been passed by the borings implemented. For this layer there are defined:

- volume density - 1,95-2,0 g/cm³

- module of general deformation Eo=40 MPa /see Appendix B.II.4./

- calculation angle of internal friction -40°

- calculation cohesion - 0.0

- calculation loading Ro = 0,5 MPa

- category of ditch – earth

4. Conclusion

The geotechnical and hydrogeological research of both water areas were conducted in a way and in a capacity enough for the insurance of reliable geological information for projecting.

In a hydrogeological and geotechnical respect, the conditions for building on both platforms are complicated due to the presence of soils relatively unable to bear loads, swampings, high subsoil waters, big fluctuations in the level of the Danube etc. For this reason, especially precious proved to be the information acquired with field and easily portable apparatuses - penetrometer, UPI installation for geophysical studies as well as the usage of express and relatively simple for implementation methods for water-infusion.

The preparation of the entire research was in compliance with the technical task of the Assignor.

5. Hydrological research 2.2

The period of research at the ІV^th – VІ^th months of year 2003, was at the same time as the critical mode, known as “low waters” with permanent tendency of reducing.

That interlocked the opportunity for the execution of the assignment of task №2.2, including:

Accomplish measuring the level of the Danube river and branches /minimum two times/ during the period of high water at the sites: Kalimock (rkm 437.2 tо rkm 441.6) and Vejetoria (rkm 445.0 tо rkm 448.5 /Kalimock/Brushlen Marshes"/.

At the period of expansion and accomplishment of the field works, it wasn’t determined “high water” and there weren’t accomplished special measurement. There are available measurements of different points at the river water track, made at the time of the geological measurement which are systemized by time and place and are disposed, no matter that on the maps there is indication about it.

WATER LEVEL at Kalimock

N^o	X	Y	Water Level	Time and date at measurement
1	4775543.28	9513252.90	13.01	11:28:26 09.05.2003 г.
2	4775657.90	9514243.33	12.96	11:22:53 09.05.2003 г.
3	4775692.58	9515246.77	12.90	11:17:03 09.05.2003 г.
4	4775804.62	9516242.68	12.82	11:11:36 09.05.2003 г.
5	4775921.91	9517233.41	12.81	13:23:16 09.05.2003 г.
6	4776182.09	9518204.32	12.71	13:16:50 09.05.2003 г.
7	4775952.81	9519171.90	12.64	14:52:49 09.05.2003 г.
8	4775892.87	9520164.05	12.67	15:47:04 09.05.2003 г.
9	4776066.93	9521158.48	12.69	10:51:01 10.05.2003 г.
10	4776276.60	9522138.98	12.64	11:51:21 10.05.2003 г.
11	4776680.90	9523055.76	12.62	11:18:12 10.05.2003 г.
12	4777056.92	9523983.49	12.58	11:22:40 10.05.2003 г.
13	4777216.52	9525036.78	12.55	10:24:22 11.05.2003 г.
14	4777452.62	9525944.20	12.51	10:19:08 11.05.2003 г.
15	4777743.58	9526900.34	12.46	10:06:38 11.05.2003 г.
16	4778012.13	9527858.88	12.38	12:06:37 11.05.2003 г.
17	4778018.94	9528857.21	12.30	14:16:36 10.05.2003 г.
18	4777671.99	9529796.89	12.27	14:10:17 10.05.2003 г.
19	4777522.58	9530780.11	12.23	14:03:43 10.05.2003 г.
20	4777493.27	9531776.34	12.12	14:41:52 10.05.2003 г.
21	4777839.43	9532713.15	12.08	14:46:59 10.05.2003 г.
22	4778154.88	9533660.90	12.07	15:38:18 10.05.2003 г.