MIAMIDADE COUNTY REGULATORY AND ECONOMIC RESOURCE DEPT DIVISION

MIAMI-DADE COUNTY REGULATORY AND ECONOMIC RESOURCE DEPT. DIVISION OF ENVIRONMENTAL RESOURCE MANAGEMENT (DERM) “THE PERMITTING PROCESS TO DISPOSE OF STORMWATER VIA INJECTION WELL AND DEWATERING”

STORMWATER AND DEWATERING OVERVIEW Part I STORMWATER DRAINAGE WELL PURPOSE CONDITIONS WHERE STORMWATER DRAINAGE WELL APPLIES PERMITTING PROCESS PHASE I REQUIREMENTS DESIGN CRITERIA PHASE II REQUIREMENTS

STORMWATER AND DEWATERING OVERVIEW PART II DEWATERING DEFINITION DEWATERING METHODS 1. OPEN EXCAVATION 2. WELL POINT SYSTEM THE USAGE OF STORM WATER WELL IN DEWATERING PROCESS IS PERMITTED OR EXEMPTED BY DEP

PART I STORMWATER DRAINAGE WELL

PURPOSE DRAINAGE WELL IS APPLICABLE ONLY EAST OF THE SALT INTRUDED LINE (1000 mg/L CHLORIDE LINE) DRAINAGE WELL IS USED PRIMARILY IN COASTAL AREAS WHERE SEEPAGE OR TRANSMISSIVITY IS OFTEN NON-EXISTENT OR THE REQUIRED AMOUNT OF EXFILTRATION TRENCH WILL NOT FIT INTO THE PROJECT AREA

SALT WATER INTRUSION LINE MAP

MIAMI-DADE COUNTY STORMWATER DRAINAGE WELL REVIEW REQUIREMENTS THE DRAINAGE WELL APPROVAL CONSIST OF (2) TWO PHASES

PHASE I REQUIREMENTS SUBMIT A STORMWATER DRAINAGE WELL REVIEW APPLICATION FORM & FEE $210. 00

PHASE I REQUIREMENTS 3 SETS OF SIGN AND SEALED PAVING AND DRAINAGE PLANS 1 COPY OF SIGN AND SEALED DRAINAGE CALCULATION 1 COPY OF PROOF OF OWNERSHIP 1 COPY OF PLUMBING PLAN

DESIGN CRITERIA CLASS V INJECTION WELL (STORMWATER DRAINAGE WELL ) REQUIRING WATER QUALITY ANALYSES TO BE PERFORMED SHALL BE IN ACCORDANCE WITH MIAMI-DADE COUNTY CRITERIA

MIAMI-DADE COUNTY DESIGN CRITERIA DRAINAGE CALCULATIONS MUST DEMONSTRATE THE RETENTION OF 5 YEAR- 1 DAY STORM EVENT. PROVIDE WATER QUALITY PRE-TREATMENT PRIOR TO DISCHARGE INTO THE WELL. IN LIEU OF WATER QUALITY TREATMENT PROVIDE POLLUTION CONTROL BOX SIZED BASED ON 90 SECONDS DETENTION TIME

MIAMI-DADE COUNTY DESIGN CRITERIA All INTERIOR DRAINS OF PARKING GARAGE AND PLANTER DRAINS ARE SEPARATED FROM THE STORMWATER DRAINAGE WELL SYSTEM AND ARE ROUTED INTO A SPECIAL FRENCH DRAIN WITH 2 FEET SAND FILTER BELOW THE PIPE INVERT. A COPY OF THE PLUMBING PLAN MUST BE SUBMITTED FOR VERIFICATION BY DERM OF AN EFFECTIVE SEPARATION.

SPECIAL FRENCH DRAIN DIAGRAM

CALCULATION OF THE REQUIRED 90 SECONDS DETENTION CALCULATE RUNOFF BASED ON THE RATIONAL FORMULA Q= CIA REQUIRED = Q x 90 SECONDS VOLUME REQUIRED ≤ VOLUME OF BOX

DERM APPROVAL STAMP

PHASE II REQUIREMENTS THE PROPOSED SITE MUST HAVE COMPLETED PHASE I REQUIREMENTS AND COMPLIES WITH MIAMI DADE COUNTY CRITERIA. 3 COPIES OF FDEP CLASS V CONSTRUCTION AND OPERATION CLEARANCE PERMIT APPLICATION FORM. FEE $200 PER WELL

PART II DEWATERING SITE

DEWATERING SHALL MEAN TO DISCHARGE OFFSITE OR ON-SITE WATER FROM AN EXCAVATION DURING CONSTRUCTION OR EXISTING STRUCTURE FOR MAINTENANCE AND REPAIR OF UNDERGROUND UTILITIES DEWATERING CAN BE MADE BY WELL POINT SYSTEM OR OPEN EXCAVATION PUMPING

DEWATERING METHODS OPEN EXCAVATION OPEN DEWATERING SYSTEMS ENABLE ONE TO LOWER THE GROUND WATER TABLE ADEQUATELY IN COHESIVE LOW PERMEABLE SOILS. WATER IS PUMPED OFF DIRECTLY FROM SUMPS ALONG THE TOES OF THE SLOPES OF THE EXCAVATION WORKS.

OPEN EXCAVATION DEWATERING SYSTEM

DEWATERING METHODS WELL-POINT SYSTEM WELL-POINT DEWATERING SYSTEMS ENABLE TO LOWER THE GROUND WATER TABLE ADEQUATELY FOR DEEP AND LARGE CONSTRUCTION SITES. THIS DEWATERING SYSTEM IS USED IN ALL TYPES OF GROUND WHICH ARE PERMEABLE.

WELL-POINT DEWATERING SYSTEM

DEWATERING POINT OF DISCHARGE OPEN EXCAVATION DEWATERING 1. HOLE TO HOLE DISCHARGE 2. DISCHARGE TO TEMPORARY OR PERMANENT DRAINAGE SYSTEM(exfiltration trench, outfall, or drainage well) WELL POINT SYSTEM 1. DISCHARGE TO TEMPORARY OR PERMANENT DRAINAGE SYSTEM 2. DISCHARGE OFF SITE

CALCULATION OF THE REQUIRED DEWATERING OPEN HOLE DEWATERING 1. CONE OF INFLUENCE FROM DEWATERING 2. SETTLING VELOCITY IN SEDIMENTATION TANK 3. DISCHARGE CAPACITY OF EXFILTRATION TRENCH OR DRAINAGE WELL POINT SYSTEM 1. CONE OF INFLUENCE FROM DEWATERING 2. DISCHARGE CAPACITY OF DRAINAGE SYSTEM

CONE OF INFLUENCE

THE USAGE OF STORMWATER DRAINAGE WELL IN A DEWATERING PROCESS STORMWATER INJECTION WELL IS USED FOR TEMPORARY DEWATERING DISCHARGE DURING CONSTRUCTION IN CASES WHERE OFF-SITE DISCHARGE IS NOT ALLOWED OR SITE HAS SHALLOW CONTAMINATION PLUME

MIAMI-DADE COUNTY DEWATERING REQUIREMENTS TO DISPOSE INTO A STORMWATER INJECTION WELL THE PROPOSED SITE IS NOT CONTAMINATED IF THE SITE IS CONTAMINATEDOR WITHIN 500 FEET MUST OBTAIN POLLUTION REMEDIATION SECTION APPROVAL. FDEP APPROVAL IS REQUIRED CALCULATION MUST DEMONSTRATE THAT THE STORWATER INJECTION WELL IS CAPABLE TO HANDLE THE DEWATERING DISCHARGE CALCULATIONS TO REDUCE TURBIDITY DISCHARGE INTO THE WELL

WHY DO RER DERM AND FDEP REGULATE STORM WATER WELL? STORM WATER WELL IS A CONCERN BECAUSE IT MAY CONTAIN THE FOLLOWING: SEDIMENT NUTRIENTS METALS MICROORGANISMS FERTILIZERS PESTICIDES

CONCLUSION MIAMI DADE COUNTY RER DERM AND FDEP PERMITTING PROCESS TO DISPOSE OF STORM WATER VIA INJECTION WELLS IS TO ASSURE THE PROTECTION OF GROUNDWATER RESOURCE FROM CONTAMINATION