PHOENIX BORING INC., DE-FOA-0003047, GRID OVERHAUL WITH PROACTIVE, HIGH-SPEED UNDERGROUNDING FOR RELIABILITY, RESILIENCE, AND SECURITY (GOPHURRS). HETEROGENEOUS SOIL CONDITIONS WHICH INCLUDE HARD ROCK LIMIT COST EFFECTIVE UNDERGROUNDING OF ELECTRIC UTILITIES. PHOENIX BORING PROPOSES A MODIFIED HORIZONTAL DIRECTIONAL DRILLING (HDD) METHOD THAT CAN ALTERNATELY CHANGE IN SITU BETWEEN A THERMAL SPALLATION DRILL FOR HARDER ROCK AND A STANDARD CUTTERHEAD AS NEEDED TO REDUCE THE TIME AND COST TO UNDERGROUND IN HARD ROCK AND HETEROGENEOUS CONDITIONS. AS PART OF THE PROJECT PHOENIX BORING WILL COMPLETE A DETAILED DESIGN OF THE MOST CRITICAL COMPONENTS IN THEIR HDD SYSTEM INCLUDING THE COMBUSTOR FOR THERMAL SPALLATION DRILLING (TSD) AND THE HYBRID CUTTERHEAD SUCH THAT THEY CAN IDENTIFY AND ORDER LONG-LEAD AND HIGH-RISK ITEMS EARLY ON (TASK 1). THEY WILL ALSO WORK ON DEVELOPING THE TEST PROTOCOLS AND TESTING PLANS AS WELL AS DESIGNING AND BUILDING THE TEST STAND FOR THE DRILL (TASK 2). ONCE KEY DRILL COMPONENTS ARRIVE AND ARE ASSEMBLED (TASK 1) AND THE TEST STAND IS READY (TASK 2) THE TEAM WILL TEST THE COMBUSTOR AND THE HYBRID CUTTERHEAD WITH A BOULDER AS WELL AS IN SOFTER SOIL CONDITIONS (TASK 3). FINALLY, THE TEAM WILL WORK ON A FIELD-TEST READINESS PLAN (TASK 4).