TABLE 6.3. COMPOSITION OF CONTAMINATED WATERS OF TAILINGS R

			Cl–	SO2–	NO–	NH+	Fe		U		RadiumPolonium-
								total		total
	Sampling place	pH		4	3	4					226	210
			(mg/L)	(mg/L)	(mg/L)	(mg/L)	(mg/L)		(mg/L)
											(Bq/L)	(Bq/L)
	Tailings
	New	9.3	360	943	1.0	3.8	0.6		0.13		0.33	0.24
	Old	9.3	220	815	1.15	n.d.	0.1		0.1		0.10	0.02
	Release to Zheltaya River
	Tailings water	9.25	320	944	0.75	0.45	0.18		0.4		0.02	0.11
	Mine water	8.35	1130	457	0.65	n.d.	0.1		0.04		0.12	0.006
	MPC and PCingest	—	350	500	10	—	—		0.8		1.0	0.2
	according to Ref. [6.4]

n.d.: Not detected.

6.5.ASSESSMENT OF THE SOURCES OF CONTAMINATION OF NATURAL WATERS IN THE ZHOVTI VODY AREA

The water basin within the limits of Zhovti Vody town is the Zheltaya River, which is a left tributary of the Ingulets River. At present, its bed is silted, and only a small channel is cleared. The treated mine waters from the Novaya mine are discharged into it.

The length of the river is 61 km and the area of the watershed is 490 km2. The average slope of the river is 0.00175. The average annual drainage is 1.24 L·km–2·s–1. The average velocity of the current is 0.1–0.2 m/s; during flooding it increases to 0.5 m/s. Melting snow is the main contributor to flow and is responsible for two thirds of the annual drainage; rain and groundwaters are of secondary importance. For most of the year, the river bed is dry, forming chains of separated stretches, and, at some locations, the river is parched for up to 10 months. Downstream of the wastewater outlet from the uranium mill, the water has elevated levels of total dissolved solids (TDS). Table 6.4 presents the results of the chemical analysis of the river water at the town of Zhovti Vody.

There are clean water bodies within the town: in the north-eastern section there is a municipal beach, in the south-eastern section there is a beach and pond used by children, and in the eastern part there is a reservoir, Vodobud, used at present as a

reserve water body for the drinking water supply. Table 6.5 gives the results of radiochemical analysis of water samples of the Zheltaya River, starting from the source and finishing with the exit of the river beyond the limits of the town.

The results confirm contamination of the Zheltaya River with uranium from the milling operation. In the area of Netesovka the concentration of uranium in the water exceeds the concentration at the source of the river by a factor of 80. Even at a distance of more than 10 km, in the area of Annovka, high activities of natural radionuclides are apparent (Table 6.6), exceeding by ten times the activity of these radionuclides in the Saksagan and Ingulets Rivers.

Some dose estimates arising from water consumption for the most conservative scenario of water use from the Zheltaya River have been calculated for the residents of Annovka: see Section 8.4.2.

The results in Ref. [6.12] and the dose calculations presented in Section 8.4.2 show that the conservatively estimated annual doses from consumption of river water may exceed the constraint value of 0.05 mSv established in Ref. [6.4] for water use in areas of uranium mining and milling. These assessments draw attention to the problem and indicate the need for more extensive monitoring and remedial works to reduce releases of radioactive substances into the river.

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TABLE 6.4. CHEMICAL COMPOSITION OF THE WATER FROM THE ZHELTAYA RIVER AT ZHOVTI VODY (1995)

	April 1995	May 1995	June 1995
pH	7.65	8.2	8.2
Hardness (meq/L)	11.8	14	21.6
Ca + Mg (mg/L)	189	280	343
Na + K (mg/L)	104	264	360
CO3 (mg/L)	—	40	—
HCO3 (mg/L)	415	346	354
Chlorine (mg/L)	142	177	247
SO4 (mg/L)	256	650	432
NH4 (mg/L)	0.08	1	0.26
NO3 (mg/L)	n.d.	n.d.	0.17
NO2 (mg/L)	—	1.5	0.02
TDS (mg/L)	1106	1757	1380

n.d.: Not detected.

TABLE 6.5. CONCENTRATION OF NATURAL RADIONUCLIDES IN WATER FROM THE ZHELTAYA RIVER (1999)

Sampling site	Total uranium (Bq/L)	Radium-226 (Bq/L)
Zheltaya River (source)	0.08	0.013
Veselo Ivanovka reservoir	0.08	0.015
Vodobud reservoir	0.07	0.047
Stream from Vodobud reservoir	0.04	0.011
Zheltaya River (Marianovka)	2.14	0.010
Zheltaya River (Netesovka)	5.9	0.013
PCingest [6.4]	10.0	1.0

TABLE 6.6. CONCENTRATION OF NATURAL RADIONUCLIDES IN THE INGULETS, SAKSAGAN AND ZHELTAYA RIVERS (MAY–JUNE 2002)

						Activity (mBq/L)
	Sampling place										234U/238U
		Uranium-		Uranium-			Lead-	Radium-	Polonium-
		238		234			210	226	210
	Zheltaya River in Annovka in May	1020	± 100	1160	±	115	<11	8 ± 3	20	± 3	1.13
	Zheltaya River in Annovka in June	1400	± 90	1600	±	130	—	—		—	1.14
	Drinking water in Zhovti Vody	36	± 5	58	±	6	<11	5 ± 2	2.4	± 0.5	1.61
	Ingulets River in Aleksandria	35	± 5	54	±	6	<11	16 ± 5	0.4	± 0.1	1.54
	Ingulets River (Iskra reservoir)	31	± 5	48	±	6	<11	13 ± 3	0.5	± 0.2	1.54
	Saksagan River (Kress reservoir)	55	± 6	77	±	7	<11	7 ± 4	1.1	± 0.5	1.40
	PCingest [6.4]	10 000		10 000			500	1000	200

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6.6.EFFECT OF IN SITU LEACHING OF URANIUM ON CONTAMINATION OF NATURAL WATERS

6.6.1.Devladovo site

One of the former in situ leaching sites, Devladovo (see Fig. 6.1, position 17), is situated at the interfluve of the Saksagan and Kamenka Rivers. Exploitation of the deposit was completed by 1984 and the affected lands were recultivated and transferred to general land tenure [6.7, 6.13]. During decommissioning, the underground waters were found to be contaminated with naturally occurring radionuclides. The legislation then in place did not envisage restoration of the underground waters to their initial state. Until 1990, the mine water ponds remained on the Devladovo site.

The ore deposits were leached within the Buchak water bearing horizon. This horizon occupies a significant portion of the deposit; its groundwaters discharge to the Dnieper Ternovskaya valley. At present, this horizon of underground waters is contaminated with residual acid solutions containing natural radionuclides. The water-containing rocks are coal and carbon free sands up to 15 m thick. The underground water flux of this horizon is pressurized; the water pressure is 28–40 m and flow is in the direction of east to west, with slopes of the piezometric surface of 0.0015-0.0028. The valley of the Kamenka River supplies the water horizon under natural conditions. The release takes place into the Saksagan River.

The underground waters of the Buchak water bearing horizon have naturally elevated concentrations of sulphates and high TDS and, for that reason, were not used for drinking water prior to the development of the ore body. Table 6.7 gives data on the background concentrations of uranium series members taken from the horizons beyond the boundary of the impact area.

The main source of contamination of the underground waters was the leaching solutions, with typical concentrations of 10 g/L sulphuric acid and 2 g/L nitric acid. During the period of operation, 200 000 t of sulphate ion (as sulphuric acid) and 18 600 t of nitrate (as nitric acid) were pumped into the horizon. The extent of the artificial contamination from leaching covers the whole area of the former site in the direction of underground water movement from east to west in the monitored area.

The major contributors to radioactive contamination are Utotal, 210Pb and 210Po. The measured concentrations are within the following ranges:

Utotal from 2.5 to 885 Bq/L, 210Pb from 0.2 to 15 Bq/L and 210Po from 0.02 to 0.7 Bq/L.

6.6.2.Forecast of the long term potential contamination of the Saksagan River

In 1997, with the assistance of COGEMA– SGN (France) and under the TACIS programme, modelling studies were undertaken to forecast the future hydrological and radiological situation near the Devladovo site [6.14]. The task was to forecast the uranium concentrations for the next 1000 years, assuming that the object of contamination would be the Saksagan River, which is 13.5 km from the Devladovo site and the main regional source of water supply.

Two sources of contamination were considered:

(a)Pond water on the surface, contaminating the Quaternary water bearing horizon;

(b)Residual solutions from underground leaching, contaminating the Buchak water bearing horizon [6.13].

Simulation of outflow of pollutants from the waste storage pond for times in excess of 1000 years showed that, with a high probability (80%), contamination would reach the Saksagan River with concentrations exceeding the current sanitary standards [6.3–6.6]. The predicted concentrations 1000 years from now are given in Table 6.8 [6.14].

These estimates, made on the basis of measurements and simulation, show that there is no problem with current contamination of the surface water in the region. However, there is a high probability that contamination above current sanitary standards will occur from several hundred to one thousand years in the future, when polluted water containing uranium series nuclides reaches the Saksagan River. Accordingly, the movement of these contaminated groundwaters should be monitored within the framework of long term environmental programmes.

One of the priority tasks is to create an ongoing operating system for external radioecological monitoring of the environment (water, soil, vegetation, air, food products) in the regions of the former and present uranium facilities to assess the developing situation and to justify possible

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TABLE 6.7. BACKGROUND CONCENTRATION IN UNDERGROUND WATERS OF THE BUCHAK HORIZON (FOR 1998) AT LOCATIONS BEYOND THE IMPACTED AREAS [6.13]

	Well No.	SO24– (mg/L)		TDS (mg/L)			Concentration (Bq/L)
						Uranium-238	Radium-226	Thorium-230	Lead-210	Polonium-210
	1	619		2580		1.23	—	—	—	—
	2	350		1542		0.65	—	—	—	—
	3	440		1245		1.95	0.27	0.22	0.56	0.11
	5	584		1836		0.59	0.02	0.02	0.37	0.04
	6	498		2274		0.79	0.14	0.34	1.11	0.08
	14	814		2199		0.79	—	—	—	—
	33	526		2344		0.69	—	—	—	—
	34	718		1836		0.79	0.15	0.06	0.22	0.04
	98-2	4023		8062		0.59	—	—	—	—
	B-58	3353		5513		0	0.10	0.09	1.37	0.15
	B-59	297		598		0.84	0.28	0.02	0.59	0.07
	B-61	661			2686	1.77	0.01	0.60	0.51	0.04
	B-64	533		2818		0	—	—	—	—
	B-69	638		2942		0.98	0.07	0.02	0.22	0.06
	B-78	718		2242		1.28	0.10	0.09	1.07	0.09
	B-97	627		2145		0.42	—	—	—	—
	B-99	709		2428		0.59	0.24	0.07	0.67	0.07
	MPC and	500		1000		10	1	0.7	0.5	0.2
	PCingest

TABLE 6.8. ESTIMATED RADIONUCLIDE CONCENTRATION (Bq/L) WITHIN THE GROUNDWATER OF THE QUATERNARY HORIZON PREDICTED FOR 1000 YEARS FROM NOW

	Close zone of Devladovo site	Zone of observational control
Uranium-238	2.7	1.5
Radium-226	1.1	0.53
Thorium-230	0.33	0.13
Lead-210	0.86	0.53
Polonium-210	0.11	0.06

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