a so that flow through the system of passages 32 from first port 54 sequentially encounters second port 56 and then third port 58 for discharge of fluid into the wellbore 16 as will be described a second relief valve 34 b is disposed in second passage 32 b in certain preferred embodiments valve 34 b is adjacent third port 58 finally surge relieve system 30 includes a valve 60 to block back flow along the annulus of the drill string 24 in certain preferred embodiments valve 60 is a non return valve such as a float valve ball valve flapper valve or the like that is actuated by backflow through the drill string 24 in certain preferred embodiments valve 60 is positioned in the annulus 42 of tubular member 36 preferably adjacent the first end 38 uphole of passage 32 b and relief valve 34 b with on going reference to fig2 surge relief system 30 may also include a third flow passage 32 c although it may be defined in drill bit 28 in certain embodiments preferably third flow passage 32 c is disposed in tubular 36 between the first end 38 and second end 40 and uphole of second flow passage 32 b third flow passage 32 c has a forth port 62 forth port 62 is preferably positioned between the first and second ends 38 40 respectively of tubular 36 in preferred embodiments forth port 62 is uphole from third port 58 and defined.