Handbook for Methane Control in Mining - AMMSA

9211. At the surface installation (Figure 6–13), a commercially made flame arrestor will beinstalled within 10 ft of the top of the vent stack. A check valve shall be used to guard againstreversal of flow. The check valve can be manually defeated if it is desired to purge the pipelinefor repairs. An orifice meter may be installed if needed. All surface installations will be periodicallyinspected to ensure satisfactory performance.12. All boreholes drilled for degasification will be accurately surveyed either during or afterdrilling is completed using commercially available borehole surveying tools. These boreholeswill be accurately plotted on mine maps to prevent any inadvertent mining through them.13. Should an occasion arise in the future when cutting into an abandoned, unplugged boreholewill be necessary, a detailed mining plan will be submitted to MSHA.14. A compressor will be required at the surface if beneficial use is made of the gas at a futuredate. Plans for installation will be discussed with MSHA at the appropriate time.Figure 6–13.—Surface installation for horizontal drainage boreholes.