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HomeMy WebLinkAboutRS_Drainage_Report_Part_2_Page_Set_211222_v1APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-4 NO. 2 – INFILTRATION FACILITIES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Infiltration Pond, Top or Side Slopes of Dam, Berm or Embankment Rodent holes Any evidence of rodent holes if facility is acting as a dam or berm, or any evidence of water piping through dam or berm via rodent holes. Rodents removed or destroyed and dam or berm repaired. Tree growth Tree growth threatens integrity of dams, berms or slopes, does not allow maintenance access, or interferes with maintenance activity. If trees are not a threat to dam, berm, or embankment integrity or not interfering with access or maintenance, they do not need to be removed. Trees do not hinder facility performance or maintenance activities. Erosion Eroded damage over 2 inches deep where cause of damage is still present or where there is potential for continued erosion. Any erosion observed on a compacted slope. Slopes stabilized using appropriate erosion control measures. If erosion is occurring on compacted slope, a licensed civil engineer should be consulted to resolve source of erosion. Settlement Any part of a dam, berm or embankment that has settled 4 inches lower than the design elevation. Top or side slope restored to design dimensions. If settlement is significant, a licensed civil engineer should be consulted to determine the cause of the settlement. Infiltration Pond, Tank, Vault, Trench, or Small Basin Storage Area Sediment accumulation If two inches or more sediment is present or a percolation test indicates facility is working at or less than 90% of design. Facility infiltrates as designed. Liner damaged If applicable) Liner is visible or pond does not hold water as designed. Liner repaired or replaced. Infiltration Tank Structure Plugged air vent Any blockage of the vent. Tank or vault freely vents. Tank bent out of shape Any part of tank/pipe is bent out of shape more than 10% of its design shape. Tank repaired or replaced to design. Gaps between sections, damaged joints or cracks or tears in wall A gap wider than ½-inch at the joint of any tank sections or any evidence of soil particles entering the tank at a joint or through a wall. No water or soil entering tank through joints or walls. Infiltration Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch, any evidence of soil entering the structure through cracks or qualified inspection personnel determines that the vault is not structurally sound. Vault is sealed and structurally sound. AppendixGDocuSignEnvelopeID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-5 NO. 2 – INFILTRATION FACILITIES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Inlet/Outlet Pipes Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. Large access doors/plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat; covers access opening completely. Lifting rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. Infiltration Pond, Tank, Vault, Trench, or Small Basin Filter Bags Plugged filter bag (if applicable) Filter bag more than 1/ 2 full. Replace filter bag or redesign system. Infiltration Pond, Tank, Vault, Trench, or Small Basin Pre- settling Ponds and Vaults Sediment accumulation 6" or more of sediment has accumulated. Pre-settling occurs as designed Infiltration Pond, Rock Filter Plugged rock filter High water level on upstream side of filter remains for extended period of time or little or no water flows through filter during heavy rain storms. Rock filter replaced evaluate need for filter and remove if not necessary. Infiltration Pond Emergency Overflow Spillway Rock missing Only one layer of rock exists above native soil in area five square feet or larger, or any exposure of native soil at the top of out flow path of spillway. Rip-rap on inside slopes need not be replaced. Spillway restored to design standards. Tree growth Tree growth impedes flow or threatens stability of spillway. Trees removed. DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-8 NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Structure Trash and debris Trash or debris of more than ½ cubic foot which is located immediately in front of the structure opening or is blocking capacity of the structure by more than 10%. No Trash or debris blocking or potentially blocking entrance to structure. Trash or debris in the structure that exceeds 1/ 3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. No trash or debris in the structure. Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Sediment accumulation Sediment exceeds 60% of the depth from the bottom of the structure to the invert of the lowest pipe into or out of the structure or the bottom of the FROP-T section or is within 6 inches of the invert of the lowest pipe into or out of the structure or the bottom of the FROP-T section. Sump of structure contains no sediment. Damage to frame and/or top slab Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks in walls or bottom Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering structure through cracks, or maintenance person judges that structure is unsound. Structure is sealed and structurally sound. Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering structure through cracks. No cracks more than 1/ 4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Structure has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the structure at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Ladder rungs missing or unsafe Ladder is unsafe due to missing rungs, misalignment, rust, cracks, or sharp edges. Ladder meets design standards and allows maintenance person safe access. FROP-T Section Damaged FROP-T T section is not securely attached to structure wall and outlet pipe structure should support at least 1,000 lbs of up or down pressure. T section securely attached to wall and outlet pipe. Structure is not in upright position (allow up to 10% from plumb). Structure in correct position. DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-9 NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED FROP-T Section cont.) Damaged FROP-T cont.) Connections to outlet pipe are not watertight or show signs of deteriorated grout. Connections to outlet pipe are water tight; structure repaired or replaced and works as designed. Any holes—other than designed holes—in the structure. Structure has no holes other than designed holes. Cleanout Gate Damaged or missing cleanout gate Cleanout gate is missing. Replace cleanout gate. Cleanout gate is not watertight. Gate is watertight and works as designed. Gate cannot be moved up and down by one maintenance person. Gate moves up and down easily and is watertight. Chain/rod leading to gate is missing or damaged. Chain is in place and works as designed. Orifice Plate Damaged or missing orifice plate Control device is not working properly due to missing, out of place, or bent orifice plate. Plate is in place and works as designed. Obstructions to orifice plate Any trash, debris, sediment, or vegetation blocking the plate. Plate is free of all obstructions and works as designed. Overflow Pipe Obstructions to overflow pipe Any trash or debris blocking (or having the potential of blocking) the overflow pipe. Pipe is free of all obstructions and works as designed. Deformed or damaged lip of overflow pipe Lip of overflow pipe is bent or deformed. Overflow pipe does not allow overflow at an elevation lower than design Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Metal Grates If applicable) Unsafe grate opening Grate with opening wider than 7/ 8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. footnote to guidelines for disposal Damaged or missing grate Grate missing or broken member(s) of the grate. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-10 NO. 5 – CATCH BASINS AND MANHOLES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Structure Sediment accumulation Sediment exceeds 60% of the depth from the bottom of the catch basin to the invert of the lowest pipe into or out of the catch basin or is within 6 inches of the invert of the lowest pipe into or out of the catch basin. Sump of catch basin contains no sediment. Trash and debris Trash or debris of more than ½ cubic foot which is located immediately in front of the catch basin opening or is blocking capacity of the catch basin by more than 10%. No Trash or debris blocking or potentially blocking entrance to catch basin. Trash or debris in the catch basin that exceeds 1/ 3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. No trash or debris in the catch basin. Dead animals or vegetation that could generate odors that could cause complaints or dangerous gases (e.g., methane). No dead animals or vegetation present within catch basin. Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Damage to frame and/or top slab Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks in walls or bottom Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering catch basin through cracks, or maintenance person judges that catch basin is unsound. Catch basin is sealed and is structurally sound. Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering catch basin through cracks. No cracks more than 1/ 4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Catch basin has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the catch basin at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-11 NO. 5 – CATCH BASINS AND MANHOLES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Inlet/Outlet Pipe cont.) Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Metal Grates Catch Basins) Unsafe grate opening Grate with opening wider than 7/ 8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. footnote to guidelines for disposal Damaged or missing grate Grate missing or broken member(s) of the grate. Any open structure requires urgent maintenance. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-12 NO. 6 – CONVEYANCE PIPES AND DITCHES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Pipes Sediment & debris accumulation Accumulated sediment or debris that exceeds 20% of the diameter of the pipe. Water flows freely through pipes. Vegetation/root growth in pipe Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective coating or corrosion Protective coating is damaged; rust or corrosion is weakening the structural integrity of any part of pipe. Pipe repaired or replaced. Damaged pipes Any dent that decreases the cross section area of pipe by more than 20% or is determined to have weakened structural integrity of the pipe. Pipe repaired or replaced. Ditches Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 square feet of ditch and slopes. Trash and debris cleared from ditches. Sediment accumulation Accumulated sediment that exceeds 20% of the design depth. Ditch cleaned/flushed of all sediment and debris so that it matches design. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive vegetation growth Vegetation that reduces free movement of water through ditches. Water flows freely through ditches. Erosion damage to slopes Any erosion observed on a ditch slope. Slopes are not eroding. Rock lining out of place or missing (If applicable) One layer or less of rock exists above native soil area 5 square feet or more, any exposed native soil. Replace rocks to design standards. DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-13 NO. 7 – DEBRIS BARRIERS (E.G., TRASH RACKS) MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED. Site Trash and debris Trash or debris plugging more than 20% of the area of the barrier. Barrier clear to receive capacity flow. Sediment accumulation Sediment accumulation of greater than 20% of the area of the barrier Barrier clear to receive capacity flow. Structure Cracked, broken, or loose pipe or structure Structure which bars attached to is damaged – pipe is loose or cracked or concrete structure is cracked, broken, or loose. Structure barrier attached to is sound. Bars Incorrect bar spacing Bar spacing exceeds 6 inches. Bars have at most 6 inches spacing. Damaged or missing bars Bars are bent out of shape more than 3 inches. Bars in place with no bends more than ¾ inch. Bars are missing or entire barrier missing. Bars in place according to design. Bars are loose and rust is causing 50% deterioration to any part of barrier. Repair or replace barrier to design standards. DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-14 NO. 8 – ENERGY DISSIPATERS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED. Site Trash and debris Trash and/or debris accumulation. Dissipater clear of trash and/or debris. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Rock Pad Missing or moved rock Only one layer of rock exists above native soil in area five square feet or larger or any exposure of native soil. Rock pad prevents erosion. Dispersion Trench Pipe plugged with sediment Accumulated sediment that exceeds 20% of the design depth. Pipe cleaned/flushed so that it matches design. Not discharging water properly Visual evidence of water discharging at concentrated points along trench (normal condition is a “sheet flow” of water along trench). Water discharges from feature by sheet flow. Perforations plugged Over 1/4 of perforations in pipe are plugged with debris or sediment. Perforations freely discharge flow. Water flows out top of distributor” catch basin. Water flows out of distributor catch basin during any storm less than the design storm. No flow discharges from distributor catch basin. Receiving area over- saturated Water in receiving area is causing or has potential of causing landslide problems. No danger of landslides. Gabions Damaged mesh Mesh of gabion broken, twisted or deformed so structure is weakened or rock may fall out. Mesh is intact, no rock missing. Corroded mesh Gabion mesh shows corrosion through more than ¼ of its gage. All gabion mesh capable of containing rock and retaining designed form. Collapsed or deformed baskets Gabion basket shape deformed due to any cause. All gabion baskets intact, structure stands as designed. Missing rock Any rock missing that could cause gabion to loose structural integrity. No rock missing. Manhole/Chamber Worn or damaged post, baffles or side of chamber Structure dissipating flow deteriorates to ½ or original size or any concentrated worn spot exceeding one square foot which would make structure unsound. Structure is in no danger of failing. Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch or any evidence of soil entering the structure through cracks, or maintenance inspection personnel determines that the structure is not structurally sound. Manhole/chamber is sealed and structurally sound. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the structure at the joint of the inlet/outlet pipes. No soil or water enters and no water discharges at the joint of inlet/outlet pipes. DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-17 NO. 11 – GROUNDS (LANDSCAPING) MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Trees and Shrubs Hazard tree identified Any tree or limb of a tree identified as having a potential to fall and cause property damage or threaten human life. A hazard tree identified by a qualified arborist must be removed as soon as possible. No hazard trees in facility. Damaged tree or shrub identified Limbs or parts of trees or shrubs that are split or broken which affect more than 25% of the total foliage of the tree or shrub. Trees and shrubs with less than 5% of total foliage with split or broken limbs. Trees or shrubs that have been blown down or knocked over. No blown down vegetation or knocked over vegetation. Trees or shrubs free of injury. Trees or shrubs which are not adequately supported or are leaning over, causing exposure of the roots. Tree or shrub in place and adequately supported; dead or diseased trees removed. DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-19 NO. 13 – BASIC BIOSWALE (GRASS) MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and/or debris accumulated on the bioswale site. No trash or debris on the bioswale site. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Swale Section Sediment accumulation Sediment depth exceeds 2 inches in 10% of the swale treatment area. No sediment deposits in grass treatment area of the bioswale. Sediment inhibits grass growth over 10% of swale length. Grass growth not inhibited by sediment. Sediment inhibits even spreading of flow. Flow spreads evenly through swale Erosion/scouring Eroded or scoured swale bottom due to channelization or high flows. No eroded or scoured areas in bioswale. Cause of erosion or scour addressed. Poor vegetation coverage Grass is sparse or bare or eroded patches occur in more than 10% of the swale bottom. Swale has no bare spots and grass is thick and healthy. Excessive vegetation growth Grass excessively tall (greater than 10 inches), grass is thin or nuisance weeds and other vegetation have taken over. Grass is between 3 and 4 inches tall, thick and healthy. No nuisance vegetation present. Excessive shade Grass growth is poor because sunlight does not reach swale. Healthy grass growth or swale converted to a wet bioswale. Constant baseflow Continuous flow through the swale, even when it has been dry for weeks or an eroded, muddy channel has formed in the swale bottom. Baseflow removed from swale by a low- flow pea-gravel drain or bypassed around the swale. Standing water Water pools in the swale between storms or does not drain freely. Swale freely drains and there is no standing water in swale between storms. Channelization Flow concentrates and erodes channel through swale. No flow channels in swale. Flow Spreader Concentrated flow Flow from spreader not uniformly distributed across entire swale width. Flows are spread evenly over entire swale width. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-35 NO. 23 – COALESCING PLATE OIL/WATER SEPARATOR MAINTENANCE COMPONENT DEFECT CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash or debris which impairs the function of the facility. Trash and debris removed from facility. Contaminants and pollution Floating oil in excess of 1 inch in first chamber, any oil in other chambers or other contaminants of any type in any chamber. No contaminants present other than a surface oil film. Vault Treatment Area Sediment accumulation in the forebay Sediment accumulation of 6 inches or greater in the forebay. No sediment in the forebay. Discharge water not clear Inspection of discharge water shows obvious signs of poor water quality – effluent discharge from vault shows thick visible sheen. Repair function of plates so effluent is clear. Trash or debris accumulation Trash and debris accumulation in vault floatables and non-floatables). Trash and debris removed from vault. Oil accumulation Oil accumulation that exceeds 1 inch at the water surface in the in the coalescing plate chamber. No visible oil depth on water and coalescing plates clear of oil. Coalescing Plates Damaged Plate media broken, deformed, cracked and/or showing signs of failure. Replace that portion of media pack or entire plate pack depending on severity of failure. Sediment accumulation Any sediment accumulation which interferes with the operation of the coalescing plates. No sediment accumulation interfering with the coalescing plates. Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch and any evidence of soil particles entering the structure through the cracks, or maintenance inspection personnel determines that the vault is not structurally sound. Vault replaced or repaired to design specifications. Baffles damaged Baffles corroding, cracking, warping and/or showing signs of failure as determined by maintenance/inspection person. Repair or replace baffles to specifications. Ventilation Pipes Plugged ventilation pipes Any obstruction to the ventilation pipes. Ventilation pipes are clear. Shutoff Valve Damaged or inoperable shutoff valve Shutoff valve cannot be opened or closed. Shutoff valve operates normally. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-36 NO. 23 – COALESCING PLATE OIL/WATER SEPARATOR MAINTENANCE COMPONENT DEFECT CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Access Manhole cont.) Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. Large access doors/plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat and cover access opening completely. Lifting rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 CITY OF RENTON SURFACE WATER DESIGN MANUAL 2017 City of Renton Surface Water Design Manual 12/12/2016 8-A-1 REFERENCE 8-A TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Part 2 PROJECT LOCATION AND DESCRIPTION Project Owner _Home Depot, USA Inc__________ Phone _770-384-2543 x12543_______________ Address _2455 Paces Ferry, Rd C19________ Atlanta, GA 30339________________ Project Engineer _Daniel J Zoldak______________ Company _Lars Andersen & Associates, INC____ Phone _559-276-2790 Ext 117_______________ Project Name _Home Depot_____________ CED Permit # ________________________ Location Township _23N_______________ Range _5E________________ Section _SW1/4-17, NE1/4-19, NW1/7-20_ Site Address _901 S Grady Way__ Renon, WA 98057________ Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS Land Use (e.g., Subdivision / Short Subd.) Building (e.g., M/F / Commercial / SFR) Grading Right-of-Way Use Other __Site Plan Review_______________ DFW HPA COE 404 DOE Dam Safety FEMA Floodplain COE Wetlands Other ________ Shoreline Management Structural Rockery/Vault/_____ ESA Section 7 Part 5 PLAN AND REPORT INFORMATION Technical Information Report Site Improvement Plan (Engr. Plans) Type of Drainage Review check one): Date (include revision dates): 12/21/2021 Date of Final: Full Targeted Simplified Large Project Directed Plan Type (check one): Date (include revision dates): 12/22/2021 Date of Final: Full Modified Simplified DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 12/12/2016 2017 City of Renton Surface Water Design Manual 8-A-2 Part 6 SWDM ADJUSTMENT APPROVALS Type (circle one): Standard / Blanket Description: (include conditions in TIR Section 2) Approved Adjustment No. ______________________ Date of Approval: _______________________ Part 7 MONITORING REQUIREMENTS Monitoring Required: Yes / No Start Date: _______________________ Completion Date: _______________________ Describe: _________________________________ Re: SWDM Adjustment No. ________________ Part 8 SITE COMMUNITY AND DRAINAGE BASIN Community Plan: __City of Renton_______________________________________________________ Special District Overlays: __N/A_________________________________________________________ Drainage Basin: _Black River Basin________________________________________________ Stormwater Requirements: _Full Drainage Review__________________________________________ Part 9 ONSITE AND ADJACENT SENSITIVE AREAS River/Stream ________________________ Lake ______________________________ Wetlands _Adjacent to SW corner of Site__ Closed Depression ____________________ Floodplain ___________________________ Other _______________________________ Steep Slope __________________________ Erosion Hazard _______________________ Landslide Hazard ______________________ Coal Mine Hazard ______________________ Seismic Hazard _______________________ Habitat Protection ______________________ DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 REFERENCE 8-A: TECHNICAL INFORMATION REPORT (TIR) WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2017 City of Renton Surface Water Design Manual 12/12/2016 Ref 8-A-3 Part 10 SOILS Soil Type Urban________________ Slopes 0.5-25%________________ Erosion Potential Limited__________________ High Groundwater Table (within 5 feet) Other ________________________________ Sole Source Aquifer Seeps/Springs Additional Sheets Attached Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE Core 2 – Offsite Analysis_________________ Sensitive/Critical Areas__________________ SEPA________________________________ LID Infeasibility________________________ Other________________________________ LIMITATION / SITE CONSTRAINT Not exceeding existin peak flow.____________ Additional Sheets Attached Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Threshold Discharge Area: name or description) Project Area Core Requirements (all 8 apply): Discharge at Natural Location Number of Natural Discharge Locations: 2 Offsite Analysis Level: 1 / 2 / 3 dated:_____N/A_____________ Flow Control (include facility summary sheet) Standard: _Flow Control Structure_(x2)_______________________ or Exemption Number: ____________ On-site BMPs: _Biofiltration Basin (x3), Oil separator (x2)________ Conveyance System Spill containment located at: _TBD_________________________ Erosion and Sediment Control / Construction Stormwater Pollution Prevention CSWPP/CESCL/ESC Site Supervisor: __TBD________________ Contact Phone: __TBD___________________ After Hours Phone: __TBD____________________ DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 12/12/2016 2017 City of Renton Surface Water Design Manual 8-A-4 Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Maintenance and Operation Responsibility (circle one): Private / Public If Private, Maintenance Log Required: Yes / No Financial Guarantees and Liability Provided: Yes / No Water Quality (include facility summary sheet) Type (circle one): Basic / Sens. Lake / Enhanced Basic / Bog or Exemption No. _______________________ Special Requirements (as applicable): Area Specific Drainage Requirements Type: SDO / MDP / BP / Shared Fac. / None Name: ________________________ Floodplain/Floodway Delineation Type (circle one): Major / Minor / Exemption / None 100-year Base Flood Elevation (or range): _______________ Datum: Flood Protection Facilities Describe: Source Control commercial / industrial land use) Describe land use: Commercial Describe any structural controls: Oil Seperators (x2) Oil Control High-Use Site: Yes / No Treatment BMP: _________________________________ Maintenance Agreement: Yes / No with whom? _____________________________________ Other Drainage Structures Describe: DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 REFERENCE 8-A: TECHNICAL INFORMATION REPORT (TIR) WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2017 City of Renton Surface Water Design Manual 12/12/2016 Ref 8-A-5 Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION Clearing Limits Cover Measures Perimeter Protection Traffic Area Stabilization Sediment Retention Surface Water Collection Dewatering Control Dust Control Flow Control Control Pollutants Protect Existing and Proposed BMPs/Facilities Maintain Protective BMPs / Manage Project MINIMUM ESC REQUIREMENTS AFTER CONSTRUCTION Stabilize exposed surfaces Remove and restore Temporary ESC Facilities Clean and remove all silt and debris, ensure operation of Permanent BMPs/Facilities, restore operation of BMPs/Facilities as necessary Flag limits of sensitive areas and open space preservation areas Other _______________________ Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch) Flow Control Type/Description Water Quality Type/Description Detention Infiltration Regional Facility Shared Facility On-site BMPs Other Existing flow control Vegetated Flowpath Wetpool Filtration Oil Control Spill Control On-site BMPs Other Existing separators & biofiltration basins ________________ Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS Drainage Easement Covenant Native Growth Protection Covenant Tract Other __Utility Easements_______________ Cast in Place Vault Retaining Wall Rockery > 4 High Structural on Steep Slope Other _______________________________ DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 12/12/2016 2017 City of Renton Surface Water Design Manual 8-A-6 Part 17 SIGNATURE OF PROFESSIONAL ENGINEER I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attached Technical Information Report. To the best of my knowledge the information provided here is accurate. 12/22/2021__ Signed/Date DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 Terracon Consultants, Inc.21905 64th Ave. W, Suite 100 Mountlake Terrace, WA 98043 P (425) 771 3304 F (425) 771 3549 www.terracon.com LETTER HEAD September 15, 2021 The Home Depot 2455 Paces Ferry Road, C19 Atlanta, GA 30339 Attn: John R. Foy – Manager/Field Construction P:(678) 764-2837 E:john_r_foy@homedepot.com Re: Geotechnical Engineering Report –DRAFT Addendum Letter No. 1 Former Sam’s Club South Grady Way and Talbot Road Renton, WA Terracon Project No. 81195216 Dear Mr. Foy: This DRAFT addendum letter serves as an update to the existing geotechnical engineering report developed by Terracon (i.e. formerly Zipper Zeman & Associates; ZZA) dated December 6, 2002 see attached). This addendum letter was developed consistent with our proposal dated July 13, 2021. Presented in this letter are the following: Liquefaction hazard analysis results performed using current methods with previously performed boring logs (ZZA; Terra Associates; GeoEngineers) Considerations for adding piles to the existing building and new piles to building additions Preliminary recommendations for downdrag loads on existing piles as a result of post- liquefaction settlement Preliminary lateral pile recommendations for use in LPile analyses performed by the structural engineer to assess adequacy of existing piles Overview of geotechnical data gaps and recommended additional analyses to support the proposed development (see attached proposed site exploration plan) Conceptual geologic cross sections: A-A’, B-B’, C-C’, and D-D’ Photography log from a site visit performed August 26, 2021 is also attached. This addendum letter should be used with the attached geotechnical engineering report. Based on review of the construction plans and drawings, the building is support by 18-inch diameter augercast piles founded in at least 2 feet of bedrock. The augercast pile schedule is presented in the photography log that is attached at the end of this letter. Floor slabs are supported by grade beams with piles spaced approximately 20 feet. Each column is supported by a pile cap with two piles. Additional single augercast piles support the grade beams for the floor slab. The allowable pile capacity presented in the plan set is 75 tons per pile. Photos of a portion of the plan set are included in the attached photography log. AppendixIDocuSignEnvelopeID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 Geotechnical Engineering Report –DRAFT Addendum Letter No. 1 Former Sam’s Club Renton, WA September 15, 2021 Terracon Project No. 81195216 Responsive Resourceful Reliable 2 UPDATED SEISMIC CONSIDERATIONS The existing geotechnical engineering report for the project was originally published while the International Building Code (IBC) 1997 was the current code. Since that time, IBC 2018 has been adopted by Washington State, which references ASCE 7-16. This new code introduces different ground motion parameters than the previous version, including an increase in the peak ground acceleration (PGA) which is used for liquefaction evaluations. Updated seismic design parameters are presented in the table below: Description Value Site Class F Site Latitude 47.4727 Site Longitude -122.2061 SS –Short Period Spectral Acceleration, Site Class E 2 1.431 g S1 –1-Second Period Spectral Acceleration, Site Class E 2 0.488 g PGA -ASCE 7, Peak Ground Acceleration2 0.609 g FPGA –Peak Ground Acceleration Site Coefficient2 1.1 PGAM –Site-modified peak ground acceleration2 0.67 1.The IBC requires a site profile extending to a depth of 100 feet for seismic site classification. Borings were performed to the depth range of 50 to 100 feet where blow counts were used to define the site class. 2.These values were obtained using online seismic design maps and tools provided by ATC https://hazards.atcouncil.org/). LIQUEFACTION The subsurface conditions are described and presented in the geotechnical report. In general, subsurface conditions consist of fill that includes some compacted structural fill near the surface underlain by uncompacted fill that includes very loose to loose coal mine tailings, cinders, and sandstone and shale fill. The uncompacted unit of fill is underlain by alluvial soil consisting of very loose to loose sand and silty sand, very soft to soft clay, silty clay, clayey silt, silt, and peat. Sandstone bedrock underlies the alluvial soil at depths ranging from 19 to 110 feet below the ground surface that existed at the time the subsurface explorations were performed. The bedrock is described as highly weathered but becomes more competent with depth. Liquefaction was evaluated for select, full-depth borings (i.e. advanced to bedrock) from the geotechnical report using the liquefaction triggering methods proposed by Idriss & Boulanger 2014). The borings selected for analysis were based on the boring location, depth, and available data. In general, the liquefiable unit is observed to extend from the water table to denser alluvium or cohesive soils. Liquefaction is assumed to occur no deeper than 60 feet bgs. The estimated DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 Geotechnical Engineering Report –DRAFT Addendum Letter No. 1 Former Sam’s Club Renton, WA September 15, 2021 Terracon Project No. 81195216 Responsive Resourceful Reliable 3 range of liquefiable soils and the resulting free-field post-liquefaction settlement for the design level earthquake is presented in the table below: Locations 1 Depth Range of Liquefiable Unit feet bgs)2 Estimated Total Settlement inches)3 B-3 10 to 50 20 B-5 10 to 43 18 B-6 10 to 38 16 B-7 10 to 40; 55 to 60 18 B-8 10 to 28; 38 to 48 18 B-10 10 to 43; 50 to 56 26 1.Boring performed by ZZA that are presented in geotechnical engineering report. 2.Below existing ground surface (bgs) at the time of the explorations. 3.Field-field estimate. Although the borings selected were located within the building footprint, similar magnitudes of settlement should be expected for pavement areas. Smaller (but still significant) earthquakes could result in less settlement than the estimated total liquefaction as a result of the design earthquake. Considerations for differential settlement should be made for any areas of the planned development that are not pile supported. Over a span of 40 feet, we estimate the differential settlement will be on the order of 1 to 9 inches (per ASCE 7-16, Table 12.13-3). The differential settlement limit allowed by the code for preserving life safety is 4½ inches. The estimated differential settlement exceeds the code limit; therefore, mitigation (i.e. pile support) is considered to be necessary. DEEP FOUNDATIONS Conceptual Geologic Cross Sections The existing soil borings from the geotechnical engineering report and reports from others were used to generate conceptual geologic cross sections. The geologic cross sections are intended to conceptually present the extent of liquefiable soils and the sandstone bedrock contact. The cross sections can be used to evaluate pile stability with other recommendations presented in this report addendum. The cross sections are presented at this end of this letter and will be updated following the additional geotechnical explorations recommended herein and subsequent addendum letter No. 2. DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 Geotechnical Engineering Report –DRAFT Addendum Letter No. 1 Former Sam’s Club Renton, WA September 15, 2021 Terracon Project No. 81195216 Responsive Resourceful Reliable 4 Existing Pile Design and Performance Observations As mentioned previously, the building is supported by 18-inch diameter augercast piles founded in at least 2 feet of bedrock. These piles are designed with an allowable capacity of 75 tons. This translates to an allowable end bearing capacity of 85 kips per ft2. A typical factor of safety of 3 is assumed. Based on our site visit and review of exterior walls, columns, and floor slabs, the building appears to be in good condition with no areas of significant cracking or structural distress noted on the exterior walls or floor slabs. We surmise that the existing pile foundation appears to be performing well for the near 20-year old building. Given this apparent satisfactory performance, similar pile sizes and capacities could be assumed for additional piles. However, pile installation within the building may be limited, alternative pile methods such as segmental torque-down piles, in addition to augercast piles, should be considered. Pile Downdrag The phenomenon of liquefaction can have a negative impact on pile capacity due to the induced vertical loading from ground subsidence, or liquefaction-induced settlement. The zone of liquefaction, as it settles, drags with it the overlying soil overburden. Rather than providing added vertical capacity via side friction, the overlying non-liquefiable soil and liquefiable soil impart a load on the pile. The downdrag load; however, is a function of the liquefiable zone thickness, overburden soil thickness, and soil overburden composition. In general, the soil overburden thickness is roughly 10 feet while the composition is relatively variable. For purposes of this addendum letter, an average condition (thickness and composition) is assumed for estimating the downdrag load. The table below presents a range of values that can be assumed for structural analysis of pile capacity: Depth Range of Liquefiable Unit feet bgs)1,2 Estimated Downdrag Load per Pile (kips) inches)1,2 10 to 20 18 10 to 30 33 10 to 40 50 10 to 50 68 10 to 60 85 1.For values between the ranges presented, linearly interpolate. 2.See the attached conceptual geologic cross sections for evaluation of other scenarios. As discussed in the Geotechnical Data Gaps section, additional explorations are recommended along the building perimeter to improve our understanding of the depth to bedrock which will facilitate estimation of downdrag and planning of pile embedment depths. Piles terminated short of the bedrock, or in weathered bedrock, may not achieve the recommended design capacities. DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 Geotechnical Engineering Report –DRAFT Addendum Letter No. 1 Former Sam’s Club Renton, WA September 15, 2021 Terracon Project No. 81195216 Responsive Resourceful Reliable 5 The values presented in the table above are considered preliminary and are for planning purposes only. These values will be updated following completion of the soil borings as part of the recommended additional explorations and subsequent addendum letter No. 2. LATERAL PILE LOADING The following table lists input values for use in LPILE analyses. LPILE estimates values of kh and E50 based on strength; however, non-default values of kh should be used where provided, particularly for the sand strata. Since deflection or a service limit criterion will most likely control lateral capacity design, no safety/resistance factor is included with the parameters. Stratigraphy 1 L-Pile Soil Model Depth to Bottom of Stratum below existing ground surface (ft) c (psf)2 f 2 g (pcf) 2,3 50 2 K (pci)2 No.Material 1 Fill (above WT) Sand Reese) 10 0 30°120 ---25 2 Liquefiable Zone Liquefied Sand Rollins) 30 to 60 0 30°120 ------ 3 Non- Liquefiable Alluvial Soil Soft Clay Matlock) 60 to 105 1,200 0 125 0.01 125 4 Sandstone Weak Rock --- 28,000 ---145 0.001 1,000 1.See Subsurface Profile in the geotechnical engineering report provided by ZZA for more details on Stratigraphy. 2.Definition of Terms: c: Cohesive intercept f: Internal friction angle, g: Moist unit weight 50:Non-default E50 strain K: Horizontal modulus of subgrade reaction 3.Buoyant unit weight values should be used below water table (i.e.g less 62.4 pcf) When piles are used in groups, the lateral capacities of the piles in the second, third, and subsequent rows of the group should be reduced as compared to the capacity of a single, independent pile. Guidance for applying p-multiplier factors to the p values in the p-y curves for each row of pile foundations within a pile group are as follows: DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 Geotechnical Engineering Report –DRAFT Addendum Letter No. 1 Former Sam’s Club Renton, WA September 15, 2021 Terracon Project No. 81195216 Responsive Resourceful Reliable 6 Front row: Pm = 0.8; Second row: Pm = 0.4 Third and subsequent row: Pm = 0.3. For the case of a single row of piles supporting a laterally loaded grade beam, group action for lateral resistance of piles would need to be considered when spacing is less than three pile diameters (measured center-to-center). GEOTECHNICAL DATA GAPS Bedrock Depth Existing geotechnical engineering reports for the site include the ZZA report (attached) and reports by GeoEngineers and Terra Associates in 1999 and 2000, respectively. Collectively, there are 27 soil borings within 50 feet of the building; however, not all of the borings were advanced to bedrock. Along the northwest and southwest sides of the building, where the lumber rack and garden center expansions are proposed, respectively, additional explorations are necessary to understand depth to bedrock variations. Therefore, full-depth soil borings that penetrate into bedrock are recommended. The existing and proposed soil boring locations are included as an attachment to this letter. Floor Slab Evaluation Per the construction plans, the design floor slab thickness is 5 inches and is underlain by a methane barrier system. Per the recommendations in the geotechnical engineering report, the native soils are to be overlain by 12 inches of sand/gravel fill with possible use of a woven geotextile. Over the fill should be a methane/water vapor barrier followed by 6 inches of capillary break. It is not known if the layering beneath the slab was constructed as recommended in the geotechnical engineering report. Terracon proposes the following: Perform a ground penetrating radar (GPR) survey of the building slab to estimate rebar spacing, slab thickness, and presence of voids that may exist beneath the slab. Where voids are identified, perform up to 6 cores to characterize the extent of the voids if present) DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 Geotechnical Engineering Report –DRAFT Addendum Letter No. 1 Former Sam’s Club Renton, WA September 15, 2021 Terracon Project No. 81195216 Responsive Resourceful Reliable 7 If voids are not detected, perform 6 cores evenly spaced across the main part of the slab to characterize slab thickness, capillary break thickness, and presence of the methane vapor barrier Deliverable The results of the soil borings, which includes updated geologic cross sections, as well as the results of the floor slab survey, will be provided in a second addendum letter. In this letter, we provide updated estimates of liquefaction downdrag loads and LPile parameters. These recommendations are subject to refinement and revision pending the results of additional field studies. LIMITATIONS Our analysis and opinions are based upon our understanding of the project, the geotechnical conditions in the area, and the data obtained from our site exploration as well as those obtained by others. Natural variations will occur between exploration point locations or due to the modifying effects of construction or weather. The nature and extent of such variations may not become evident until during or after construction. Terracon should be retained as the Geotechnical Engineer, where noted in this report, to provide observation and testing services during pertinent construction phases. If variations appear, we can provide further evaluation and supplemental recommendations. If variations are noted in the absence of our observation and testing services on-site, we should be immediately notified so that we can provide evaluation and supplemental recommendations. Our Scope of Services does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken. Our services and any correspondence or collaboration through this system are intended for the sole benefit and exclusive use of The Home Depot for specific application to the project discussed and are accomplished in accordance with generally accepted geotechnical engineering practices with no third-party beneficiaries intended. Any third-party access to services or correspondence is solely for information purposes to support the services provided by Terracon to The Home Depot. Reliance upon the services and any work product is limited to The Home Depot, and is not intended for third parties. Any use or reliance of the provided information by third parties is done solely at their own risk. No warranties, either express or implied, are intended or made. Site characteristics as provided are for preliminary design purposes and not to estimate construction costs. Any use of our report in that regard is done at the sole risk of the cost estimator as there may be variations on the site that are not apparent in the data that could significantly DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 Geotechnical Engineering Report –DRAFT Addendum Letter No. 1 Former Sam’s Club Renton, WA September 15, 2021 Terracon Project No. 81195216 Responsive Resourceful Reliable 8 impact construction costs. Any parties charged with estimating construction costs should seek their own site characterization for specific purposes to obtain the specific level of detail necessary for costing. Site safety, and cost estimating including, excavation support, and dewatering requirements/design are the responsibility of others. If changes in the nature, design, or location of the project are planned, our conclusions and recommendations shall not be considered valid unless we review the changes and either verify or modify our conclusions in writing. We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this letter, or if we may be of further service in the meantime, please contact us. Sincerely, Terracon Consultants, Inc. DRAFT Zachary L. Koehn, P.E. Dennis R. Stettler, P.E. Project Engineer Senior Engineering Consultant Attachments: Exploration Site Plan (includes existing and proposed explorations) Conceptual Geologic Cross Sections (A-A’, B-B’, C-C’, D-D’) Photography Log ZZA Geotechnical Engineering Report (2002) DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 EXPLORATION PLAN AND CROSS SECTIONS Home Depot - Sam's Club Site Renton, WA September 14, 2021 Terracon Project No. 81195216 AERIAL PHOTOGRAPHY PROVIDED BY MICROSOFT BING MAPS DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 DEPTH BGS (AT TIME OF DRILLING, FEET)- 80-70-60-50-40-30-20- 80-70-60-50-40-30-20- 10010-90-100-110-120-130-80- 80-70-60-50-40-30-20- 10010-90-100-110-120-130-80- 80-70-60-50-40-30-20- 10010-90-100-110-120-130-80- Photography Log Home Depot – Sam’s Club Site Renton, WA September 15, 2014 Terracon Project No. 81195216 Responsive Resourceful Reliable PHOTOGRAPHY LOG 1 of 6 PHOTOGRAPHY LOG Store front entrance from inside From store front entrance looking toward middle of floor DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 Photography Log Home Depot – Sam’s Club Site Renton, WA September 15, 2014 Terracon Project No. 81195216 Responsive Resourceful Reliable PHOTOGRAPHY LOG 2 of 6 Typical perimeter wall and column Loading dock area from inside the building DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 Photography Log Home Depot – Sam’s Club Site Renton, WA September 15, 2014 Terracon Project No. 81195216 Responsive Resourceful Reliable PHOTOGRAPHY LOG 3 of 6 Typical interior column. Minor slab cracking. Slab cracking within loading dock area DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 Photography Log Home Depot – Sam’s Club Site Renton, WA September 15, 2014 Terracon Project No. 81195216 Responsive Resourceful Reliable PHOTOGRAPHY LOG 4 of 6 Loading dock area from outside the store Southwest side of store DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 Photography Log Home Depot – Sam’s Club Site Renton, WA September 15, 2014 Terracon Project No. 81195216 Responsive Resourceful Reliable PHOTOGRAPHY LOG 5 of 6 General notes for foundations and slabs from construction plan set Sample of augercast pile layout from construction plan set DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65 Photography Log Home Depot – Sam’s Club Site Renton, WA September 15, 2014 Terracon Project No. 81195216 Responsive Resourceful Reliable PHOTOGRAPHY LOG 6 of 6 Augercast pile schedule from construction plan set DocuSign Envelope ID: 6314EAD5-0BEB-42DD-88C0-371F2EBC8E65