ENVIRONMENTAL IMPACT ASSESSMENT RESULTS

Physiographical, Topographical, and Relief Features

The Munyati-Muzvezve riverbed lies on confluence 18°22'12.48" S, 22°34'44.55" E. It has a very severe and rigorous topography. Its elevation is 932 m above sea level upwards.

TABLE 5.4

Potential Environmental Impacts of Gold Panning

water due to erosion

(Continued)

ElAs and Mitigation

TABLE 5.4 (CONTINUED)

Potential Environmental Impacts of Gold Panning

EIA for Cold Panning 137

Water Quality

The area around the confluence has low population density with low irrigation intensity. In addition, there are no major sources of organic pollution. The absence of industries implies that there is no pollution loading from this source as well.

Soil Quality

Soil is sandy loam (outside the riverbed) with presence of free acids and likely occurrence of exchangeable aluminum. From dispersion ratio, it is assumed that hydraulic conductivity is very low. Electrical conductivity is normal and porosity is good for drainage. This soil is good for agriculture and horticulture crops, pH shows a strongly acidic nature, and the organic carbon content is good. In the riverbed, sand ranges between 0.5-2 m deep and clayey, dark soil with gold deposits is available.

Faunal Diversity

The entire land of the proposed project has practically no forest cover. The animal habitat is concentrated outside the riverbed, while some animals have adapted to the riverine environment. Many arthropods such as coleopterans, arachnids, and insects were observed on the isolated forest patches.

Socioeconomic Studies

Water Source

The people of the affected villages generally use the water from surrounding boreholes. The population generally fishes from isolated pools in the riverbed.

ASSESSMENTS OF IMPACTS

Based on the project details and the baseline environmental status, potential impacts as a result of the preparation and operation on the proposed area exist. Project impacts have been identified.

Impacts on Land Environment

The major anticipated impacts during the preparation phase are as follows:

i. Impacts due to excavation operations

ii. Impacts due to operation of construction equipment

iii. Impacts due to soil erosion

iv. Impacts due to sand disposal

v. Impacts due to construction of roads and houses from the sand supplies

Impacts due to Excavation Operations

During the preparation phase, various types of equipment will be brought to the site. These include mechanical separators, batching plants, and earth movers. The siting of this construction equipment would require a significant amount of space. Similarly, space will be required for storing of various other construction equipment. In addition, land will also be temporarily acquired for the duration of project preparation for storing the excavated material before sending for separation. Efforts must be made for proper siting of these facilities (Mineo Consortium, 2000). During the construction phase, there will be increased vehicular movement for transportation of various construction materials to the project site. A large quantity of dust is likely to be entrained due to the movement of trucks and other heavy vehicles. However, such ground-level emissions do not travel for long distances. In addition, there are no major habitations in the project area. Thus, no significant impacts are anticipated on this account.

Impacts due to Soil Erosion

The runoff from the construction sites will have a natural tendency to flow towards the river. For some distance downstream of major construction sites, such as dams, powerhouses, etc., there is a possibility of increased sediment levels which will impede light penetration, in turn reducing photosynthetic activity which depends directly on sunlight. This change is likely to have an adverse impact on the primary biological productivity of the affected stretch of river and its tributaries. The impact is likely to be greater for the smaller rivers/rivulets where large flow is not available for dilution or are seasonal in nature.

Impacts on Water Quality

The major sources of water pollution during project construction phase are as follows:

i. Sewage from labor camps/colonies

ii. Effluent from slime dams

Sewage from Labor Camps

About 100 workers are likely to congregate during the project construction phase. The domestic water requirement of the employee population is expected to be of the order of 10 000 L/day. It is assumed that about 80% of the water supplied will be generated as sewage.. The biological oxygen demand (BOD) load contributed by domestic sources will be about 23.7 kg/day. Even if the sewage is discharged without treatment, the minimum flows in the river are much higher than this flow; hence no major adverse impacts are anticipated. However, the sewage generated from labor colonies should be treated before disposal. Normally, during project construction, the labor population will be concentrated at 1 location.

Effluent from Mechanical Separators

During the preparation phase, at least one separator near the powerhouse site will be commissioned. The total capacity of the separator is likely to be of the order of 120— 150 HP. Water is required to wash the mixture. About 0.1 m³ of water is required per ton of material separated. The effluent from the mechanical separator would contain high suspended solids. The quantum of effluent generated is of the order of 12-15 m³/hr. The discharge from the separators does not need to be treated before its disposal on land and/or water. The various aspects covered as a part of impact on water quality during project operation phase are:

i. Effluent from project colony

ii. Impacts on reservoir quality

iii. Eutrophication risks

Effluent from Project Colony

During the operation phase, the cause and source of water pollution will be much different than that during construction. Since only about 10 people will reside in the area in a well-designed colony with sewage treatment plant and other infrastructural facilities, the problem of water pollution due to disposal of sewage is not anticipated. In the operation phase, about 10 people are likely to be residing in the project area, resulting in about 50 L/day of sewage at 5 L/person. Proper disposal measures for sewage are required to be implemented at the project.

Impacts on Reservoir Water Quality

The flooding of previously forested and agricultural land in the submergence area will increase the availability of nutrients from decomposition of vegetative matter. Phytoplankton productivity can supersaturate the euphotic zone with oxygen before contributing to the accommodation of organic matter in the sediments. Enrichment of impounded water with organic and inorganic nutrients will be the main water quality problem immediately on commencement of the operation. However, this phenomenon is likely to last for a short duration of a few years from the filling up of the reservoir.

Impacts on Terrestrial Flora

A few people (20) including technical staff and workers are likely to congregate in the area during the project construction phase. It can be assumed that the technical staff will be of higher economic status, will live in a more urbanized habitat, and will not use wood as fuel, if adequate alternate sources of fuel are provided. However, workers and other population groups residing in the area may use fuel wood for which firewood/coal depot could be provided. The workers may also cut trees to meet their requirements for cooking. Normally in such situations, a lot of indiscriminate use or wastage of wood is also observed. Hence, to avoid felling of trees by the laborers, alternate fuel supply must be provided.

Acquisition of Forest Land

A very limited area outside the riverbed would be required for the mining operations. People will be restricted to areas without vegetation.

Disturbance to Wildlife

Based on the interaction with locals, it was confirmed that within the submergence area, no major wildlife is observed. It would be worthwhile to mention here that most of the submergence area lies within the gorge portion. The river acts as a barrier to movement of wildlife even in the pre-project stage. Thus, the creation of a reservoir due to the proposed project is not expected to cause any adverse impact on wildlife movement.

Impacts on Wildlife Sanctuaries

The resuscitation of the river will attract the wildlife back for water consumption and as habitat.

Impact on the Aquatic Ecology

During the construction phase of the preparation of the project, a large quantity of building material like stones, pebbles, gravel, and sand would be needed for construction of various project appurtenances. The cumulative impact of this activity may result in increased turbidity levels. Good dredging practice can, however, minimize turbidity. The second important impact is on the spawning areas of cold-water fisheries. Almost all the cold-water fish breed in the flowing waters. The spawning areas of these fish species are found amongst pebbles, gravel, sand, etc. The eggs are sticky in nature and remain embedded in the gravel and subsequently hatch. Any disturbance of the stream bottom will result in adverse impacts on fish eggs. Thus, if adequate precautions during dredging operations are not undertaken, then significant adverse impacts on aquatic ecology are anticipated.

The pools will change the slow-flowing river to a fast-flowing one. The positive impact of the project will be the formulation of a water body which can be used as commercial fish stocks to meet the protein requirement of the region. Since construction of the pools affects the flow of water in the river, the riverbed below the river site gets invariably affected and many a time a long stretch of riverbed downstream of pools gets affected due to reduction in the quantum of water. However, the minimum flow of water required for the maintenance of aquatic flora and fauna, especially fish, must be maintained downstream of the pools at least up to the tail water discharge point. Proper measures for fish conservation and management may be proposed in the EMP report. The restoration of pools also will not affect the water requirement of the population residing in the downstream areas. This population generally depends upon the local streams and springs for drinking purposes and for other domestic uses. There is also no competitive use of water downstream of river for industrial purposes. Therefore, the impact of pooling in the downstream areas is not anticipated.

Impact on the Noise Environment

In a water resource project, the impacts on ambient noise levels are expected only during the project construction phase, due to operation of various construction equipment. Likewise, noise due to quarrying, vehicular movement, and excavation operations will have some adverse impact on the ambient noise levels in the area. Since there are no major habitats in the nearby areas of the project site, it is not likely to have any effect in that regard. No major wildlife is observed in and around the project site. Hence, no significant impacts on wildlife are anticipated as a result of excavation activities.

Air Pollution

In a water resources project, air pollution occurs mainly during the project construction phase. The major sources of air pollution during construction phase are due to fuel combustion from various equipment, emissions from various crushers, and fugitive emissions from various sources. The short-term increase in SO₂, even assuming that all the equipment is operating at a common point is quite low. Hence, no major impact on ambient air quality is anticipated. However, a plan for air quality management is required to be formulated especially for the construction stage of the project in which there will be considerable movement of vehicles and operation of various equipment which may impair the air quality of the project area.

Impacts on the Socioeconomic Environment

The preparation phase will last for about 2 weeks. The highest number of the labor force is estimated at about 100. During the construction phase, the basic problem will be the management of many workers migrating to the construction area in search of jobs. Those who would migrate to this area are likely to come from various parts of the country having different cultural, ethnic, and social backgrounds. Such a mixture of population has its own advantages and disadvantages. The advantages include exchange of ideas and cultures between various groups of people which would not have been possible otherwise. Due to longer residence of this population in one place, a new' culture, having a distinct socioeconomic similarity w'ould develop which will have its own identity.

The availability of infrastructure is generally a problem during the initial construction phase, though the construction workers can be compensated for certain facilities like health and education. The facilities of desired quality are often not made available in the initial stages. The adequacy of water supply, sew'age treatment, and housing should therefore be ensured before and adequate measures be taken at the very start of the project.