Site Name: SOUTH CAVALCADE STREET
EPA ID: TXD980810386 EPA Region: 06 Metro Statistical Area: 3360
CAVALCADE AND MAURY STREETS, HOUSTON, TX 77020
Operable Unit:
ROD ID: EPA/ROD/R06-88/045 ROD Date: 09/26/88
Contaminant: VOCS; BENZENE; TOLUENE; XYLENES; PAHS; METALS; ARSENIC; CHROMIUM; LEAD
Keys: NONE
Abstract:
THE 66-ACRE SOUTH CAVALCADE SITE IS LOCATED IN NORTHEAST HOUSTON, TEXAS. THE SURROUNDING AREAS ARE A MIXTURE OF RESIDENTIAL, COMMERCIAL, AND INDUSTRIAL PROPERTIES. STORMWATER RUNOFF FLOWS TO TWO STORMWATER DRAINAGE DITCHES, WHICH FLOW INTO HUNTING BAYOU, A LIMITED AQUATIC HABITAT AS CLASSIFIED BY TEXAS WATER QUALITY STANDARDS. THE SITE WAS USED AS A WOOD PRESERVING AND COAL TAR DISTILLATION FACILITY FROM 1910 TO 1962. THE WOOD PRESERVING FACILITY CONSISTED OF AN OPERATIONS AREA, A DRIP TRACK, AND TREATED AND UNTREATED WOOD STORAGE AREAS. THE OPERATIONS AREA INCLUDED WOOD-TREATING CYLINDERS, CHEMICAL STORAGE TANKS, AND A WASTE WATER LAGOON. CREOSOTE AND METALLIC SALTS WERE USED IN THE OPERATION. SUBSEQUENTLY, THE SITE WAS SOLD, DIVIDED INTO SMALLER TRACTS, AND RESOLD TO THE CURRENT OWNERS. THE SITE IS CURRENTLY USED BY THREE COMMERCIAL TRUCKING COMPANIES, WHICH HAVE ERECTED FOUR BUILDINGS ON THE NORTHERN AND SOUTHERN PARTS OF THE SITE. IN 1983, THE HOUSTON METROPOLITAN TRANSIT AUTHORITY INVESTIGATED THE SITE FOR POTENTIAL MASS TRANSIT USE AND FOUND EVIDENCE OF BURIED CREOSOTE. BEGINNING IN NOVEMBER 1985, EPA SAMPLED ALL ENVIRONMENTAL MEDIA AND FOUND TWO DISCRETE AREAS OF CONTAMINATION AT THE SITE CORRESPONDING TO THE FORMER LOCATIONS OF THE WOOD TREATING OPERATIONS AND COAL TAR PLANT IN THE SOUTHERN PORTION OF THE SITE, AND A POND PREVIOUSLY EXISTING IN THE NORTHERN PORTION OF THE SITE. PAHS, VOCS, METALS AND COMPONENTS OF CREOSOTE WERE DETECTED IN THE SOIL, SEDIMENTS, AND GROUND WATER. THE PRIMARY CONTAMINANTS OF CONCERN AFFECTING THE GROUND WATER, SOILS, AND SEDIMENTS ARE VOCS INCLUDING BENZENE, TOLUENE, AND XYLENES, OTHER ORGANICS INCLUDING PAHS, AND METALS INCLUDING ARSENIC, CHROMIUM, AND LEAD.
THE SELECTED REMEDIAL ACTION FOR THIS SITE INCLUDES:
* EXCAVATION AND ONSITE WASHING OF 19,500 YD3 OF SOIL, REPLACING THE SOIL IN THE EXCAVATED AREAS AND CAPPING, AND TREATING WASH WATER IN THE GROUND WATER TREATMENT SYSTEM;
* IN SITU SOIL FLUSHING OF 10,500 YD3 OF SOIL;
* GROUND WATER PUMP AND TREATMENT OF 50,000,000 GALLONS USING PHYSICAL/CHEMICAL SEPARATION, PRESSURE FILTRATION, AND CARBON ADSORPTION WITH RE-INJECTION INTO THE AQUIFER OR, IF NECESSARY, DISCHARGE TO THE ONSITE DRAINAGE DITCH WHICH FLOWS INTO HUNTING BAYOU;
* OFFSITE INCINERATION OR RECYCLING OF ALL NON-AQUEOUS PHASE LIQUIDS SEPARATED OUT FROM THE GROUND WATER; AND
* GROUND WATER MONITORING.
ALTERNATIVELY, IN SITU BIOLOGICAL TREATMENT OF SOIL AND GROUND WATER WILL BE CONSIDERED IF A POTENTIALLY RESPONSIBLE PARTY CAN DEMONSTRATE ITS EQUIVALENT OR SUPERIOR PERFORMANCE AND IMPLEMENTABILITY COSTS. THE ESTIMATED PRESENT WORTH COST FOR THIS REMEDIAL ACTION IS $13,000,000.
Remedy:
SOIL REMEDIATION - DURING THE INITIAL STAGES OF THE REMEDIAL DESIGN, CONTAMINATED SOIL AREAS WILL BE SAMPLED TO BETTER DEFINE AREAS WHICH REQUIRE REMEDIATION. ALL AREAS WILL BE REMEDIATED WHERE CONTAMINANTS IN SOILS EXCEED EITHER THE RISK-BASED OR LEACHING POTENTIAL-BASED REMEDIAL GOALS. THE RISK-BASED GOAL IS 700 PPM BASED ON INGESTION AND DIRECT CONTACT WITH SOILS AS PREVIOUSLY PRESENTED IN SECTION 4.3. THE LEACHING POTENTIAL- BASED GOAL WILL BE DETERMINED BY THE EPA TOXICITY CHARACTERISTIC LEACHING PROCEDURE (TCLP) TEST. EPA BELIEVES THAT THE TCLP TEST WILL REQUIRE REMOVAL OF TOTAL PAHS AT LEVELS ABOVE 150 PPM BECAUSE THE LEACHING TEST DURING THE FEASIBILITY STUDY DEMONSTRATED LEACHING AT THIS LEVEL. THERE ARE APPROXIMATELY 30,000 CUBIC YARDS WHICH MAY NEED REMEDIATION.
IN THE SOUTHEAST CORNER OF THE SITE, APPROXIMATELY 19,500 CUBIC YARDS OF CONTAMINATED SOILS WILL BE EXCAVATED AND TRANSPORTED TO THE SOIL WASHING FACILITY WHICH WILL BE CONSTRUCTED IN THE CENTER PORTION OF THE SOUTH CAVALCADE SITE. WASH WATER FROM THE UNIT WILL BE TREATED FOR REMOVAL OF CONTAMINANTS IN THE GROUNDWATER TREATMENT SYSTEM. THE CLEANSED SOILS WILL BE RETURNED TO THE EXCAVATIONS AND CAPPED WITH CONCRETE TO MAINTAIN SOIL STABILITY.
IN THE OTHER PARTS OF THE SITE, CONTAMINATED SOILS WILL BE REMEDIATED USING IN SITU SOIL FLUSHING. THE CONTAMINANTS WHICH TRAVEL INTO THE GROUNDWATER WILL BE EXTRACTED AND TREATED IN THE CARBON ADSORPTION WASTE WATER TREATMENT SYSTEM.
GROUNDWATER REMEDIATION - GROUNDWATER WILL BE REMEDIATED THROUGH EXTRACTION AND TREATMENT OF CONTAMINATED GROUNDWATER, WITH RE-INJECTION TO INCREASE THE HYDRAULIC GRADIENT AND FLOW VELOCITIES. APPROXIMATELY 50 MILLION GALLONS OF GROUNDWATER WILL NEED TO BE PROCESSED SEVERAL TIMES TO RECOVER AND TREAT THE NAPLS. GROUNDWATER COLLECTION WILL CONTINUE UNTIL THE GROUNDWATER CONTAMINANTS HAVE BEEN RECOVERED TO THE MAXIMUM EXTENT POSSIBLE. THIS POINT WILL BE DETERMINED DURING THE REMEDIAL ACTION BASED UPON OPERATIONAL EXPERIENCE IN USING THE COLLECTION AND TREATMENT SYSTEM, AND IT MUST BE AS CLOSE TO DRINKING WATER STANDARDS AND NO DETECTABLE CARCINOGENIC PAHS TO THE MAXIMUM EXTENT POSSIBLE. AFTER THIS POINT IS REACHED, THE GROUNDWATER COLLECTION WILL CEASE AND ANY REMAINING CONTAMINATION BE ALLOWED TO NATURALLY ATTENUATE TO BACKGROUND LEVELS.
GROUNDWATER WILL BE EXTRACTED AND RE-INJECTED IN A SERIES OF THREE GROUNDWATER EXTRACTION LINES AND TWO GROUNDWATER INJECTION LINES IN THE SOUTHERN PART OF THE SITE, AND A MINIMUM OF ONE EXTRACTION LINE AND RE-INJECTION LINE IN THE NORTHERN PART. THESE WELLS WILL BE SCREENED IN THE SHALLOW AQUIFER (APPROXIMATELY 10 - 20 FEET BELOW GRADE) AND IN THE INTERMEDIATE DISCONTINUOUS SAND LENSES (APPROXIMATELY 50 FEET BELOW GRADE). THE ACTUAL NUMBER OF LINES, LOCATIONS AND SPACINGS OF WELLS AND WELL LINES WILL BE REFINED DURING REMEDIAL DESIGN.
THE GROUNDWATER WILL BE TREATED AT AN ON-SITE WASTEWATER TREATMENT PLANT CONSTRUCTED IN THE CENTER AREA OF THE SITE. GROUNDWATER WILL BE PUMPED INTO A PHYSICAL/CHEMICAL SEPARATOR FOLLOWED BY A PRESSURE FILTER AND AN ACTIVATED CARBON FILTER. ANY NAPLS COLLECTED AND SEPARATED FROM THE GROUNDWATER WILL BE RECYCLED AS CREOSOTE OR ELSE INCINERATED OFF-SITE. THE WATER WILL BE TREATED TO THE REMEDIAL GOALS PREVIOUSLY LISTED. CLEANSED GROUNDWATER WILL BE RE-INJECTED INTO THE AQUIFER ALONG WITH SURFACTANTS TO HELP RECOVER THE CONTAMINANTS. ANY EXCESS WATER WILL BE DISCHARGED TO THE DRAINAGE DITCH LEADING INTO THE OFF-SITE HUNTING BAYOU IN ACCORDANCE WITH AN NPDES PERMIT.
ALTERNATE REMEDIATION PLAN - IF A POTENTIALLY RESPONSIBLE PARTY (PRP) CAN SHOW THAT IN SITU BIOLOGICAL TREATMENT OF SOIL AND GROUNDWATER WILL PROVIDE EQUAL OR BETTER PERFORMANCE, AND IF THE PRP CAN FURTHER ENSURE THAT THE IMPLEMENTABILITY QUESTIONS CAN BE RESOLVED, EPA WILL CONSIDER THESE ALTERNATIVES (#6 AND #9). IN THIS CASE, THE PERFORMANCE GOALS AND THE GROUNDWATER EXTRACTION SYSTEM WILL BE IDENTICAL TO EPA'S SELECTED REMEDY, BUT THE ACTUAL METHOD OF TREATMENT WILL DIFFER. GROUNDWATER WILL BE TREATED ABOVE GROUND IN THE PHYSICAL/CHEMICAL SEPARATOR AND INJECTED WITH NUTRIENTS AND OXYGEN (IF NECESSARY). THE TREATED GROUNDWATER WILL BE ADDED TO THE CONTAMINATED SOIL AREAS AND RE-INJECTED INTO THE AQUIFER SYSTEM TO ENCOURAGE BIOLOGICAL DEGRADATION OF CONTAMINANTS UNDER THE GROUND. ANY EXCESS WATER WILL BE DISCHARGED INTO THE CITY SEWER SYSTEM IN ACCORDANCE WITH A PRETREATMENT PERMIT AND TREATED IN A CITY MUNICIPAL TREATMENT PLANT.
OPERATION AND MAINTENANCE - THE NEED FOR FUTURE OPERATION AND MAINTENANCE SHOULD BE MINIMIZED SINCE THE PRIMARY SOURCES OF CONTAMINATION WILL BE REMOVED THROUGH TREATMENT. SITE OPERATION AND MAINTENANCE WILL INCLUDE INSTALLING A WELL SCREENED IN THE 500 FOOT SAND, MONITORING GROUNDWATER WELLS, AND MONITORING AMBIENT AIR DURING REMEDIATION. THE GROUNDWATER MONITORING PROGRAM WILL CONTINUE FOR AT LEAST 30 YEARS UNLESS IT CAN BE SHOWN DURING THE REMEDIAL DESIGN, BASED ON THE RESULTS OF THE PILOT GROUNDWATER COLLECTION SYSTEM, THAT SOME SHORTER LENGTH OF TIME IS APPROPRIATE. THIS SAMPLING PROGRAM WILL MONITOR THE EFFECTIVENESS OF THE SELECTED REMEDY AND PROVIDE THE DATA NECESSARY TO TRIGGER FUTURE CORRECTIVE ACTION, IF NECESSARY. IF THE MONITORING SHOWS LEACHING FROM SOILS NOW UNDER EXISTING STRUCTURES, THEN THE SITE WILL NEED TO BE REVISITED TO DETERMINE IF FURTHER REMEDIATION IS NECESSARY.
ADDITIONAL SITE MAINTENANCE WOULD INCLUDE, BUT NOT NECESSARILY BE LIMITED TO, INSPECTIONS OF SURFACE VEGETATION, ENSURING PROPER DRAINAGE, AND PROPER OPERATION OF ANY ACTIONS SUCH AS GROUNDWATER TREATMENT WHICH MAY EXTEND BEYOND THE TIME REQUIRED FOR THE SOURCE CONTROL REMEDY. THE DETAILS OF THESE ACTIVITIES WILL BE DEFINED IN THE OPERATION AND MAINTENANCE PLAN OF THE REMEDIAL DESIGN. THE MONITORING DATA WILL BE EVALUATED DURING THE AGENCY'S 5-YEAR REVIEW, IN ACCORDANCE WITH SARA SECTION 121 (C), TO DETERMINE IF ANY CORRECTIVE ACTION IS NECESSARY.