LINER AND COVER CONSTRUCTION BASICS Presented by: Curt Ahrendsen, Principal American Environmental Consulting AEC

Construction Requirements and Controls Are Related To: Applicable Regulations Approved Engineering Design Plan Approved Construction Quality Assurance Plan AEC

Applicable CDPHE Regulations WHILE THERE IS NOT SPECIFIC REFERENCE TO CONSTRUCTION CONTROLS, THE COLORADO REGULATIONS REFER TO CONSTRUCTION ACTIVITIES BEING SIGNED OFF ON BY A LICENSED PROFESSIONAL ENGINEER IN THE STATE AS MEETING THE DESIGN REQUIREMENTS. AEC 6 CCR Part I REGULATIONS PERTAINING TO SOLID WASTE DISPOSAL SITES AND FACILITIES

Applicable CDPHE Regulations continued 3.2 DESIGN REQUIREMENTS All portions of the facility design and investigations must be reviewed and sealed by a Colorado professional engineer or reviewed by a professional geologist, as appropriate Prior to the acceptance of waste, the owner or operator must submit a report to the Department and the local governing body having jurisdiction documenting that the designed construction has been completed in accordance with the approved plan. The report shall be signed by a Colorado registered professional engineer, approved by the Department and placed in the operating record Quality assurance and quality control reports shall be developed and implemented for all engineered structures at the landfill. AEC

3.4 RECORDKEEPING An operating record shall be maintained and include, as a minimum, the following:….. (D) Construction as-built details Following closure of each landfill phase, the owner or operator must submit a report to the Department documenting that closure has been completed in accordance with the approved closure plan. The report, which must be signed by a Colorado registered professional engineer, shall be approved by the Department and placed in the operating record. AEC Applicable CDPHE Regulations continued

APPROVED ENGINEERING DESIGN PLAN INCLUDES: LINER SYSTEMS LEACHATE COLLECTION SYSTEMS FINAL COVER COMPONENTS SURFACE WATER CONTROLS AEC

LINER SYSTEMS AND COMPONENTS FOUNDATION AND BARRIER LAYERS USING SOILS FLEXIBLE MEMBRANE LINERS GEOSYNTHETIC CLAY LINERS AEC

TYPICAL GCL/SOIL LINER SYSTEM

PROCESSING SOIL FOR LINER SYSTEM

TYPICAL FML LINER SYSTEM

LEACHATE COLLECTION AND RECOVERY SYSTEMS Drainage Layers of Aggregate Geocomposite Materials Sump Designs Riser Pipes Lateral Drainage Pipes AEC

FABRICATING SUMP RISER PIPE

PLACING SUMP DRAIN MATERIAL

PLACING CELL FLOOR DRAIN MATERIAL

FINAL COVER COMPONENTS Foundation Layers Barrier Layers Rooting and Frost Layers Vegetation Layers Flexible Membrane Liners Geosynthetic Clay Liners Alternate Final Covers AEC

SURFACE WATER CONTROLS Channels Retention/Detention Ponds Drop Structures Spillways Rip Rap, Armoring, Etc for Erosion Control AEC

PRECONSTRUCTION DOCUMENTATION Drawings, CQA Plan, Technical Specifications, Bid Packages Generally done for each construction event at that time (except CQA Plan unless modified) Sometimes documents must be submitted for regulatory approval before construction Establish survey design coordinates, elevations, and acceptable tolerances before job starts! AEC

BIDDING Lines of authority for all or portions of the project (who contracts and pays who) Information necessary so all parties are clear on responsibilities, what is known and not known, procedures and costs for unknowns, schedules and any penalties for exceeding (weather days), anticipated quantities and payment rates if actuals are over or under. If earthworks particularly is contracted, it is critical to establish who is responsible for the surveys and lines of authority. Problems can result if this isn’t clear. Put all responsibility you can on the contractor to familiarize himself with the job so there are few disputes. –Pre-bid meeting –Pre-construction meeting AEC

PRECONSTRUCTION WORK Why Worry About It?? Avoid delays and additional costs during construction Some components of construction need to be protected soon after placement, i.e., GCL and rain, membranes-fabric-GCL and wind. AEC

Know the area to be built and have all design survey data prepared and checked. Have all stockpile areas identified. Have all quantities determined before hand; earthworks, synthetics, piping. Have sufficient soil data so no delays occur during construction, and make sure all soils materials meet specifications. Don’t forget drainage sand/gravel as well. AEC PRECONSTRUCTION WORK continued

Have all material certifications reviewed to ensure they comply with the specifications and requirements. Establish a schedule for each component so that personnel, contractors, and materials can be ready to go when needed without delay. Know all equipment that will be needed, and have readily available. Compactors, backhoe or excavator for trenches, lifting/unloading equipment for rolled materials. Tie-ins with previous construction is critical. Must be able to document continuous liner and leachate collection system. Tie-in is often very difficult. AEC PRECONSTRUCTION WORK continued

SURVEY GRID AND POINTS

Construction Quality Assurance (CQA) Includes procedures and requirements to ensure engineering design plan and specifications are met in the field. Necessary for proper construction and to obtain approval from regulators for disposal in a cell or closure of a cell. AEC

Oversight and Inspection Part time oversight of excavation, generally full time of all else Need to observe equipment used, verify proper materials, and procedures, be able to deal with problems as they occur Survey and/or review of data. Certified by PLS or PE Need constant attention to need for survey data. Check off survey points as certified-don’t do any more work once certified Pay attention to allowable tolerances As-built should generally be demonstrated by survey data, not by statement of PE or PLS! AEC Construction Quality Assurance Plan Components

Soil Liner Testing Required soil types and test parameters established before construction, i.e., grain size requirements, Atterberg Limits, density and moisture window to result in required permeability. Want to get as much “real time” approval as possible during construction to avoid delays or reworking areas. If additional soil is needed during construction, can often just do grain size and Atterberg limits to verify same soil type as previously approved. Need to plan ahead and get data before needed. AEC Construction Quality Assurance Plan Components

Soil Liner Testing (continued) Generally have a permeability specification; demonstrated by a previous laboratory relationship between density and moisture, and resulting permeability. Appropriate density and moisture is verified in field by nuclear methods (real time), and can be verified by sampling and lab testing. Followed up by limited number of permeability confirmation samples. Liner needs to be placed and compacted in controlled lifts. How to control lift thickness? Because of close tolerances, some contractors find it simpler to very slightly overbuild (1- 2”) and shave off to final grades. Needs to be surveyed when graded. AEC Construction Quality Assurance Plan Components

AEC Construction Quality Assurance Plan Components GCL Testing Little actual field testing needed. Verify that the material delivered and used is what was approved by Certification sheets May need to do confirmation testing of properties on delivered material. Oversight generally limited to inspection for damage, proper placement, overlaps, direction, anchoring, and maintaining protection from moisture.

AEC Construction Quality Assurance Plan Components FML Testing Field testing includes trial welds to ensure equipment is working correctly under field conditions, seam leak testing, and field weld strength testing. Field testing usually has a required frequency (100 percent of seams leak tested, 1 seam strength test every 500 linear feet of seam, etc.) Ensure proper overlaps, seaming equipment, alignment of panels, anchoring, inspection for defects and holes, and repair and testing of defective/damaged areas. Weather/temperature affects wrinkling/trampolining. Can’t have large wrinkles when covered. Sometimes must cover during cooler weather at night.

AEC Construction Quality Assurance Components Assisting Contractors Questions will arise during construction. CQA personnel should be able to answer/assist appropriately during construction. Need to be careful of responsibility when directing contractors

AEC Construction Quality Assurance Components Documentation Necessary to document all aspects of construction to demonstrate proper construction for regulatory approval, assist in correcting problems that are evident later, and critical when building next phase, cell or module. SURVEY-SURVEY-SURVEY!! Soils – pre-construction lab data, test data and test locations during construction. Make sure required test frequency and results meet requirements. Note failing areas-all failing areas must be corrected, retested and documented.

AEC Construction Quality Assurance Components Documentation (continued) Synthetics – GCL, PVC, HDPE, Fabric, etc. Have all required certification sheets, have list of all rolls delivered to site and installed (should match certification sheets), record distinct panel numbers, what roll they came off of, where placed and limits, unique seam numbers. Record all testing and document test locations, document location of all repairs. Will need to do as-built that includes panel numbers, seam numbers, test locations and numbers, and repairs

AEC Construction Quality Assurance Components Documentation (continued) Drainage Materials – sand/gravel or geocomposites. If sand/gravel, must verify at required frequency that meets requirements. If change source, need to re-verify. Pay attention to thickness. If geocomposite used, little field testing necessary, but CQA similar to GCL and FML. Piping-must have certification sheets showing piping used meets requirements. Piping may have to be surveyed to verify proper location-end-points should almost always be surveyed for future location.

AEC Construction Quality Assurance Components Final Report ; Certified by P.E.-Necessary to Get Regulatory Approval Narrative Survey Data Laboratory soils and sand/gravel data for materials used Soils field test data and locations Synthetic materials certification sheets Field test data and locations for synthetic materials As-built drawings. May have more than one showing different horizons.