TETRA TECH, INC.

CONTRACTOR SHALL PROVIDE TECHNICAL DESIGN SERVICES FOR PLANNING & CONDUCTING CLEANUP VERIFICATION OF, TCRA, PILOT STUDIES, OR REQUIREMENTS AT TRONOX COVE TRANSFER STATION COMPLETE (CTS), ACCESS ROADS IN NN UNDER THE RAES 2 CONTRACT #68HE0923D0002

CONTRACTOR WILL ASSIST EPA IN COMMUNITY INVOLVEMENT OUTREACH SUPPORT INCLUDING CALLS, REMOTE MEETINGS AND FACE TO FACE ASSEMBLIES; WORK WILL ALSO INVOLVE RESEARCH FOR EPA.

THE CONTRACTOR SHALL PROVIDE TECHNICAL ASSISTANCE FOR OPERATING UNMANNED AERIAL VEHICLES & SYSTEMS ON NAVAJO NATION IN ACCORDANCE WITH THE PROVISIONS OF THE EPA POLICY ON UAV/UAS UNDER THE RAES2 CONTRACT #68HE0923D0002 FOR EPA FOR REGIONS 6 &

THE CONTRACTOR SHALL PROVIDE TECHNICAL ASSISTANCE TO USEPA FOR TECHNICAL ASSISTANCE TO THE CONTAMINATED STRUCTURES PROGRAM UNDER THE RAES 2 CONTRACT.

THE CONTRACTOR PROVIDE TECHNICAL SUPPORT AND ASSISTANCE FOR THE USEPA NAVAJO ABANDONED URANIUM MINES (NAUM) PROGRAM AS IT DEVELOPS PROGRAM STANDARDS, TRAININGS AND WORKSHOPS, AND OTHER TECHNICAL SUPPORT WORK NEEDED FOR SITE INVESTIGATION.

THE CONTRACTOR SHALL PROVIDE SUPPORT NEEDED FOR TIME-CRITICAL REMOVAL ACTION (TCRA) PLANNING AND OVERSIGHT SUPPORT ASSOCIATED WITH THE OLD CHURCH ROCK MINE SITE, AS WELL AS PLANNING AND SCOPING FOR A NON-TIME CRITICAL REMOVAL ACTION (NTCRA) ENGINEERI

ENVIRONMENTAL ASSESSMENT REPLACEMENT OF THE AIR ROUTE SURVEILLANCE RADAR (ARSR) ON MT. KA`ALA, OAHU, HAWAII

THE PURPOSE OF THIS TASK ORDER IS TO PROVIDE TECHNICAL SUPPORT TO EPA REGION 6 IN FULFILLMENT OF ITS RESPONSIBILITIES FOR OVERSIGHT AND ENFORCEMENT OF ARCO'S ONGOING RI/FS UNDER THE ASAOC AND TO ASSIST EPA IN COORDINATION AND COMMUNICATION WITH

THE CONTRACTOR SHALL PERFORM REQUIRED TO CONDUCT THE ENGINEERING EVALUATION/COST ANALYSIS (EE/CA) AND RELATED TASKS AT THE FOLLOWING TRONOX ABANDONED URANIUM MINES LOCATED IN NAVAJO NATION'S NORTHERN AGENCY. THIS IS A TASK ORDER UNDER RAES 2 CON

THE CONTRACTOR SHALL PROVIDE THE SUPPORT NEEDED FOR TECHNICAL DESIGN SERVICES,& PLANNING AND CONDUCTING CLEANUP VERIFICATION OF TCRAS, PILOT STUDIES, OR OTHER INTERIM ACTIONS AT TRONOX AUMS UNDER THE RAES II CONTRACT #68HE0923D0002 FOR EPA FOR RE

THE CONTRACTOR SHALL PROVIDE EVALUATIONS FOR THE REMAINING KNOWN 278 UNFUNDED AUMS AND MINE AREAS ON THE NAVAJO NATION UNDER THE NN-AUM RESPONSE ASSESSMENT AND EVALUATION SERVICES (RAES) II CONTRACT FOR EPA FOR REGIONS 6 & 9.

THE CONTRACTOR SHALL PROVIDE TECHNICAL ASSISTANCE TASKS TO SUPPORT AGENCY OVERSIGHT OF REMOVAL SITE EVALUATIONS (RSES), INTERIM REMOVAL ACTIONS, ENGINEERING EVALUATION AND COST ANALYSIS (EE/CA), AND ANY OTHER ACTIVITY AT THE ABANDONED URANIUM MINES (

THE PURPOSE OF THIS NO-COST, BILATERAL MODIFICATION IS TO EXTEND THE POP END DATE BY TWELVE (12) MONTHS FOR RUBY MINES - NAVAJO NATION AUM RESPONSE ASSESSMENT AND EVALUATION SERVICES (RAES) II FOR EPA FOR REGIONS 6 & 9..

THE PURPOSE OF THIS MODIFICATION IS UPDATE THE SCOPE OF WORK TO INCLUDE ADMINISTRATION, MAINTENANCE, AND SUPPORT FOR NAUM SERVER INFRASTRUCTURE (TASK 7), ADD FUNDING TO CONTINUE WORK TASKS WITHIN ORIGINAL SOW AND MODIFICATIONS AND EXTEND THE PERIOD O

THE PURPOSE OF THIS BILATERAL MODIFICATION IS TO INCREASE THE LEVEL-OF-EFFORT AND FUNDING; TO 16 UNDER RAES 2 CONTRACT #68HE0923D0002.

THE PURPOSE OF THIS MODIFICATION IS TO REPLACE THE PRIMARY TOCOR WITH A NEW PRIMARY. THE PREVIOUS PRIMARY TOCOR SHALL BECOME THE ALTERNATE TOCOR.

THE PURPOSE OF THIS NO-COST MODIFICATION IS TO EXTEND THE PERIOD OF PERFORMANCE FOR R6 SCMB- TO 23 - NAVAJO NATION AUM RESPONSE ASSESSMENT AND EVALUATION SERVICES (RAES) II FOR EPA FOR REGIONS 6 & 9.

THE PURPOSE OF THIS NO-COST, BILATERAL MODIFICATION IS TO EXTEND THE PERIOD OF PERFORMANCE AND ADD A NEW ALTERNATE TOCOR. THE CONTRACTOR SUPPORTS AGENCY OVERSITE OF RSES,, INTERIM RAS, WATER STUDIES, EE/CAS, AND RAS AUMS IN THE PHASE 2 EXPANDED TRUST

THE PURPOSE OF THIS NO-COST BILATERAL MODIFICATION P00006 IS TO EXTEND THE PERIOD OF PERFORMANCE. THE CONTRACTOR SHALL PROVIDE SUPPORT NEEDED FOR NTCRA PLANNING AND OVERSIGHT ON BABBITT RANCHES UNDER RAES 2 CONTRACT #68HE0923D0002.

THE PURPOSE OF THIS NO-COST, UNILATERAL MOD IS TO ADD AND REMOVE A TOCOR. TO IS FOR AGENCY OVERSIGHT OF UNC/GE WORK AT NECR MINE SITE UNDER RAES 2 CONTRACT.

THE PURPOSE OF BI-LATERAL MODIFICATION IS TO EXTEND THE POP. CONTRACTOR WILL PERFORM EE/CAS AT THE SECTION 32/33 MINES FOR THE RAES II CONTRACT.

THE PURPOSE OF THIS BILATERAL MODIFICATION IS TO EXTEND THE POP. CONTRACTOR WILL PERFORM EE/CA TASKS AT THE QUIVIRA MINE FOR THE RAES 2 CONTRACT.

P00009 RAES 2 - INCREASE CEILING AMOUNT AND INCORPORATE A CLAUSE- NAVAJO NATION AUM RESPONSE ASSESSMENT AND EVALUATION SERVICES (RAES) II FOR EPA FOR REGIONS 6 & 9.

THE PURPOSE OF THIS MODIFICATION IS TO EXTEND THE PERIOD OF PERFORMANCE.