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• • <br />' <br />August 19, 1999 MEMORANDUM <br />993 -2057 <br />' The second potential mechanism is the loss of brine along the cement bond following <br />cement damage due to heat from the process fluids. As for the first mechanism, the <br />groundwater hazard is negligible to high, but the likelihood is negligible since the cement is <br />designed for high temperature service and is generally separated from the hottest pipe and <br />fluids by the fluid cushion and any loss of integrity would show in the volume monitoring. <br />Again the overall risk is judged to be negligible. <br />' 8.3 Pipelines <br />' Three potential failure mechanisms have been identified in connection with the pipelines. <br />The first mechanism is the rupture of the pipeline due to equipment traffic, extreme storm <br />events, or vandalism. This would result in negligible hazards to groundwater and surface <br />' water and a medium to high hazard to soils. Subsidence hazards are also considered to be <br />negligible. In the event of a rupture it is expected that solution discharge from the pipeline <br />' would be approximately 400 gpm with approximately 25 percent sodium bicarbonate. A <br />rupture of this magnitude is expected to be controlled within 20 minutes of occurrence. <br />This would result in the discharge of approximately 8,000 gallons of pregnant soda liquor. <br />The volume of sodium bicarbonate would be about 270 cu. ft. resulting in a medium to <br />high hazard to soils. The initiating events and likelihood of occurrence are considered to <br />be very low due to good design and construction of the pipeline out of Sch. 80 steel and <br />' safety berms. Magnitude and duration are expected to be medium due relatively rapid <br />recognition of the rupture. As pregnant liquor cools and flows across the soil in immediate <br />area of the pipeline approximately 70 per of the sodium bicarbonate will precipitate. <br />Pathways of exposure are limited to the soils and vegetation directly contacted by the <br />pregnant liquor. The pipeline will be placed between two containment berms to control <br />and collect any spillage due to a rupture. The topsoil resource will be removed and <br />stockpiled for reclamation. The soil or foundation material within the bermed area below <br />the pipeline is part of the industrial disturbance and represents a less significant <br />environment at risk than native soils and vegetation in an undisturbed area. The bermed <br />area is graded to drain to the lined drainage collection pond near the well field. The <br />pathway for exposure is very low due to the drainage control and collection. The overall <br />' consequence assessment is that medium to high environmental consequences could occur <br />due to the high hazard and medium magnitude and duration of exposure. However, the <br />overall risk characterization is controlled by the very low likelihood of occurrence, the <br />' very low risk pathways, and the environment at risk is contained within the industrial area. <br />As a result the risk characterization is described as very low. Proposed mitigation in <br />addition to the operational controls identified in the operating plan are presented on Table 1 <br />' and discussed in Section 9. <br />Pipeline leaks are the second category of potential pipeline failure mechanisms. Leaks <br />could result from either mechanical failure (i.e. leaks at gaskets, valves or other pipe <br />fittings) or pipe corrosion. The hazard assessment for pipeline leaks is negligible for <br />subsidence, groundwater and surface water contamination. However, the hazard <br />' \GA1_DEN1\PRO3ECTS\WP\99\2O57\2O57TM1.DOC Golder Associates <br />