HOW 100 KM PLANETESIMALS FORM FROM SMALLER MM-CM SIZED PEBBLES IS ONE OF THE BIGGEST UNANSWERED QUESTIONS IN SOLAR SYSTEM FORMATION. WITH THE DISCOVERY OF THE STREAMING INSTABILITY A ROBUST CANDIDATE HAS EMERGED FOR CLUMPING THESE PEBBLES TO THE POINT OF GRAVITATIONAL COLLAPSE ALLOWING THEM TO FORM LARGER BODIES. HOWEVER THERE REMAIN TWO LARGELY UNRESOLVED ISSUES WITH THIS PROCESS. FIRST THE STREAMING INSTABILITY WILL ONLY TRIGGER CLUMPING FOR A SUFFICIENTLY LARGE CONCENTRATION OF PEBBLES A CONDITION THAT IS NOT ALWAYS EASILY MET IN DISKS WITH A SMOOTH MONOTONIC RADIAL STRUCTURE. ADDITIONALLY THE INITIAL PLANETESIMAL SIZE DISTRIBUTION THAT ARISES FROM NUMERICAL SIMULATIONS IS SIGNIFICANTLY MORE TOP-HEAVY COMPARED WITH OBSERVED SMALL BODY SOLAR SYSTEM POPULATIONS. ANOTHER ADVANCEMENT IN RECENT YEARS HAS BEEN THE REALIZATION THAT PRESSURE TRAPS I.E. LOCAL GAS PRESSURE ENHANCEMENTS ARE LIKELY PREVALENT IN PROTOPLANETARY DISKS ARISING FROM A VARIETY OF PROCESSES E.G. THE OUTER EDGE OF PLANET-INDUCED GAPS. WHILE THE IMPORTANCE OF THESE TRAPS HAS BEEN REALIZED IN THE CONTEXT OF PLANET FORMATION AS A WHOLE THEIR ROLE IN PLANETESIMAL FORMATION VIA THE STREAMING INSTABILITY HAS ONLY BARELY BEEN EXPLORED. THUS STUDYING THE INTERACTION BETWEEN THESE PRESSURE TRAPS AND STREAMING-INDUCED PLANETESIMAL FORMATION IS ESSENTIAL FOR SEVERAL REASONS. FIRST AS MENTIONED ABOVE THESE TRAPS ARE MORE LIKELY THAN NOT TO EXIST IN PROTOPLANETARY DISKS. SECOND WHILE THESE TRAPS MAY LOCALLY ENHANCE THE CONCENTRATION OF PEBBLES TO STREAMING-UNSTABLE VALUES THESE EFFECTS MUST COMPETE WITH MOMENTUM FEEDBACK FROM THE PEBBLES ONTO THE PRESSURE TRAP WHICH COULD DEFORM THE TRAP AND ACTUALLY REDUCE CLUMPING. FINALLY IF THESE TRAPS CAN SURVIVE THEY COULD POTENTIALLY CHANGE THE INITIAL PLANETESIMAL SIZES (SINCE STREAMING-UNSTABLE WAVELENGTHS WILL DECREASE NEAR THE TRAP PEAK) AND/OR THE SIZE DISTRIBUTION (IF THE TRAPS MAINTAIN A PEBBLE CONCENTRATION CLOSE TO GRAVITATIONALLY INSTABILITY PLANETESIMALS MAY FORM ONE-BY-ONE EACH OF ROUGHLY THE SAME SIZE EQUATING TO A MORE BOTTOM HEAVY DISTRIBUTION). THUS WE AIM TO TEST WHETHER PRESSURE TRAPS WILL (A) SURVIVE THE MOMENTUM FEEDBACK FROM PEBBLES TO PRODUCE SIGNIFICANT CLUMPING AND (B) CHANGE THE RESULTING PLANETESIMAL SIZES AND/OR SIZE DISTRIBUTION. PRESSURE TRAPS COULD ALSO PLAY A CRUCIAL ROLE IN PLANET FORMATION. FOR EXAMPLE AS JUPITER IS BEING FORMED IT WILL OPEN A GAP THAT GENERATES A PRESSURE TRAP EXTERIOR TO ITS ORBIT. PLANETESIMALS FORMED FROM THIS TRAP COULD CRITICALLY INFLUENCE THE EVOLUTION OF THE SOLAR SYSTEM IN ANY COMBINATION OF THREE POSSIBILITIES: THESE PLANETESIMALS MAY MERGE AND/OR ACCRETE PEBBLES TO EVENTUALLY FORM SATURN BE SCATTERED AWAY FROM THE PLANET SOME OF WHICH MAY BE DEPOSITED AS VOLATILE RICH ASTEROIDS IN THE MAIN BELT AND/OR BE ACCRETED BY JUPITER PROVIDING THE SOURCE OF JUPITER'S OBSERVED SUPER-SOLAR METALLICITY. IN THIS PROPOSAL WE WILL USE STATE-OF-THE-ART CODES ATHENA (A GAS+PARTICLE DYNAMICS CODE) AND LIPAD (A PLANET FORMATION CODE) TO CARRY OUT THE MOST IN-DEPTH STUDY TO DATE TO TEST THESE CRITICAL IDEAS. SPECIFICALLY OUR PROPOSED WORK IS OUTLINED INTO THREE TASKS: TASK 1: USE ATHENA TO TEST WHETHER PRESSURE TRAPS WILL SURVIVE FEEDBACK FORCES TO ENHANCE CLUMPING. TASK 2: USE ATHENA TO TEST WHETHER PRESSURE TRAPS WILL CHANGE THE SIZES AND/OR SIZE DISTRIBUTION OF PLANETESIMALS. TASK 3: USE LIPAD TO DETERMINE WHETHER PLANETESIMALS PRODUCED IN A PRESSURE TRAP INDUCED BY PROTO-JUPITER WILL LEAD TO THE FORMATION OF SATURN'S CORE BE SCATTERED INTO THE ASTEROID BELT AND/OR ENRICH JUPITER'S ATMOSPHERE.