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Contaminated Soil Management Plan - Library - April 11, 2007 A 1 iI 'I i GEoErvciH¢exS I VIII cif t III ' glulll 1 Earth Scienc. Technology i 1�. rrr • CONTAMINATED SOIL MANAGEMENT PLAN TIGARD LIBRARY "x TIGARD, OREGON APRIL 11, 2007 FOR CITY OF TIGARD w wr rlri 1rr om GEOENGINEERS File No.4025-003-02 1111 Contaminated Soil Management Plan Tigard Library Tigard, Oregon File No. 4025-003-02 April 11, 2007 Prepared for: City of Tigard 13125 SW Hall Boulevard Tigard, Oregon 97223 w. Attention: Mr. Dennis Koellermeier Prepared by: ri. GeoEngineers, Inc. 15055 SW Sequoia Parkway, Suite 140 Portland, Oregon 97224 r Chris Breemer R.G. Senior Project Manager i'john H. Biggane Principal CWB:JHB:gaw it PORT: P:\4\4025003\02\Finals\402500302Soi1MgmtPlan.doc Disclaimer:Any electronic form,facsimile or hard copy of the original document(email,text,table,and/or figure),if provided,and any attachments are only a copy of the original document. The original document is stored by GeoEngineers,Inc.and will serve as the official document of record. irr Copyright©2007 by GeoEngineers,Inc. All rights reserved. rn rr1 File No.4025-003-02 TABLE OF CONTENTS Page No. 1.0 INTRODUCTION............................ 1 ............................................................................. 2.0 BACKGROUND......................................................................................................................................1 3.0 NATURE AND EXTENT OF CONTAMINATION ...................................................................................1 4.0 SOIL AND GROUNDWATER CONDITIONS.........................................................................................2 5.0 CONTAMINANT INFORMATION AND WORKER EXPOSURE INFORMATION .................................2 6.0 HANDLING AND DISPOSITION PLAN FOR CONTAMINATED SOIL AND GROUNDWATER..........2 6.1 IDENTIFICATION OF POTENTIALLY CONTAMINATED SOIL..................................................2 w 6.2 HANDLING OF CONTAMINATED SOIL......................................................................................3 6.3 EROSION CONTROL ..................................................................................................................4 6.4 SOIL STOCKPILE TESTING .......................................................................:...............................4 r� 6.5 DISPOSITION OPTIONS FOR SOIL...........................................................................................4 7.0 WALL STREET EXTENSION AND ASSOCIATED IMPROVEMENTS.................................................4 7.1 ROADWAY, DRIVEWAY, AND PARKING LOT IMPROVEMENTS .............................................5 r7.2 WETLAND MITIGATION..............................................................................................................5 7.3 STREAM RESTORATION... 5 7.4 STORMWATER RETENTION POND..........................................................................................6 rir7.5 RE-USE OF NATIVE SOIL...........................................................................................................6 8.0 CONTAMINATED SOIL VOLUMES.......................................................................................................6 r9.0 LIMITATIONS.........................................................................................................................................7 List of Figures irr Figure 1. Contaminated Soil Areas rr� r�r rlr File No.4025-003-02 page i GWENGINEERi April 11,2007 �w .r rr CONTAMINATED SOIL MANAGEMENT PLAN TIGARD LIBRARY TIGARD, OREGON rrr 1.0 INTRODUCTION o This soil management plan (SMP) outlines procedures for proper handling of arsenic-contaminated soil during construction and maintenance activities at the Tigard Library, located at 13500 SW Hall Boulevard in Tigard, Oregon. This plan is intended to address arsenic-contaminated soil that is present in portions of the site. The identified extent of contaminated soil is shown on Figure 1. The site is listed with the Oregon Department of Environmental Quality (DEQ) as Environmental Cleanup Site Information (ECSI) site number 4063. rrr This plan is intended for general site use by the City of Tigard (City) and their contractors, to minimize risks to worker health/safety and the environment and to outline procedures for handling and disposal of arsenic contaminated soil encountered during construction and maintenance activities. This plan is also specifically intended to provide information and guidance to contractors working on the proposed Wall Street extension and associated improvements, including wetland mitigation and stream restoration. 2.0 BACKGROUND Soil in portions of the site is contaminated by arsenic. It is likely that the source of the arsenic is pesticides or herbicides that were historically applied to off-site orchards formerly located to the west of the site. Based on the distribution of arsenic in site soil, it appears that the arsenic was transported to the site in shallow drainage swales that transect the site in two general areas: 1) a swale that flowed west-east ,err across the south portion of the site and 2) a swale that flowed southwest-northeast across the middle of the site. Several phases of soil assessment and remediation have been completed at the site. Apex Environmental Consulting Services, Inc. (Apex)completed two phases of soil assessment in 2002 and 2003 and managed the removal of approximately 3,682 tons of contaminated soil in 2004. Hahn Associates, Inc. (HAI) conducted additional assessment and managed the removal of 155 tons of contaminated soil in 2005. HAI summarized the results of their investigation and remediation, as well as previously completed work in the October 6, 2006"Draft Supplemental Site Investigation Report". The City is planning to extend the Wall Street right-of-way across the southern portion of the site, through areas where arsenic-contaminated soil is present. As part of the road improvement activities, the City will also conduct wetland mitigation activities and restore a portion of the Pinebrook Stream, a do seasonal stream that currently flows through a buried culvert in the southern portion of the site. In the future, the City will likely need to conduct additional construction, maintenance, and landscaping activities in arsenic-impacted areas. This soil management plan is intended to provide soil management guidance for those activities. 3.0 NATURE AND EXTENT OF CONTAMINATION wr Arsenic has been detected in soil between the surface and approximately 6 feet below ground surface (bgs) at concentrations exceeding the DEQ Default Background Concentration for arsenic (7 milligrams per kilogram [mg/kg]). Generally, arsenic contamination is limited to the upper 2 to 3 feet of soil. The File No.4025-003-02 Page 1 GWENGINEERS/ April 11,2007 irr highest concentrations of arsenic have been detected in the swale that runs west-east across the southern portion of the site. In the eastern portion of that Swale, arsenic has been detected at concentrations as high as 113 mg/kg (sample "W" collected between the surface and 1 foot bgs). Near the southwest corner of rIr the site, arsenic has been detected at concentrations as high as 264 mg/kg (sample "12S DUP", collected between the surface and 2.8 feet bgs). The area from which sample "12S DUP" was collected is covered by asphalt concrete and is under the SW Hall Boulevard right-of-way. The area from which sample "W" was collected is scheduled to be covered by the proposed Wall Street right-of-way extension. The approximate extent of arsenic-contaminated soil is shown on Figure 1. 4.0 SOIL AND GROUNDWATER CONDITIONS Soil at the site consists of silt with varying amounts of clay and sand. Organic-rich soil is present in some areas, specifically in the low-lying area at the southeast portion of the site near Fanno Creek. Depth to +■► groundwater varies, from approximately 8 feet bgs at the southwest corner of the site to approximately 2 feet bgs near Fanno Creek. 5.0 CONTAMINANT INFORMATION AND WORKER EXPOSURE INFORMATION Arsenic is the only contaminant of concern that has been identified at the site. Arsenic is considered a potential carcinogen. Health effects from unacceptable levels of arsenic exposure include ulcerated nasal septum, dermatitis, gastrointestinal disturbances, peripheral neuropathy, respiratory irritation, and hyperpigmentation of skin. Potential exposure pathways for arsenic in soil include direct contact, ingestion, and inhalation. To complete any of these exposure pathways,the soil must be exposed. Covers that can prevent or reduce exposure include vegetation, geotextile, plastic, bark dust, imported soil, asphalt, and concrete. The maximum detected concentration of arsenic (264 mg/kg) at the site does not exceed the DEQ generic risk-based concentration (RBC) for the excavation worker exposure scenario. However, arsenic concentrations at many site areas do exceed DEQ's generic RBCS for construction and occupational worker scenarios. RBCS are conservative screening levels. Under some circumstances, exposure to chemical concentrations that exceed RBCs can lead to unacceptable human health risks; however, contaminant mitigation measures, discussed in Section 6.0, can significantly reduce risks to human health. 6.0 HANDLING AND DISPOSITION PLAN FOR CONTAMINATED SOIL AND GROUNDWATER irr This section is intended to provide guidance to the City and their contractors regarding: 1) identification; 2)characterization; 3) handling and 4)disposal of contaminated soil that may be encountered during construction, maintenance, and landscaping activities at the site. 6.1 IDENTIFICATION OF POTENTIALLY CONTAMINATED SOIL w 1. Personnel that may contact contaminated soil shall review this plan to familiarize themselves with the locations of soil contamination prior to beginning the construction, maintenance, or landscaping activities. 2. All soil in the areas shown on Figure 1 shall be treated as contaminated and shall be handled and characterized as described below. File No.4025-003-02 Page 2 GWENGINEER� April 11,2007 wr 6.2 HANDLING OF CONTAMINATED SOIL 1. Any soil that is contaminated shall require special handling and disposal. Workers that conduct routine maintenance and landscaping activities that are limited in duration (i.e. the workers will be exposed to contaminated soil for less than 7 days per year), should be provided with contaminant awareness training. Contaminant awareness training should include discussion of the nature and extent of contamination, the hazards posed by contamination, and risk mitigation rn measures. HAZWOPER-certified personnel are not required for routine maintenance and landscaping activities. 2. To mitigate potential risks to workers, during all soil disturbing activities in contaminated areas (as shown on Figure 1), care should taken to minimize worker exposure to soil. During all soil disturbing activities, personnel shall: a) remove soil and dust from clothing to the extent practicable following soil disturbance, b) wash hands prior to the consumption of any food or beverage, and c) refrain from eating, smoking, or drinking while in contaminated portions of the site. Techniques that may be useful for mitigating exposure include wetting soil to minimize airborne dust, providing washing stations for removing soil from skin, and removing dust from clothes to the extent possible at the end of work shifts. 3. If extended or large-scale (i.e. utility excavations or road and parking area construction) soil disturbance is planned and/or personnel will be exposed to contaminated soil for more than 7 days per year), upon initiation of those activities, an air sample should be collected from breathing space that is representative of a worst-case worker exposure scenario. The air sample should be analyzed for arsenic. If arsenic is detected in the air sample at a concentration that exceeds the Occupational Safety and Health Administration (OSHA) Permissible Exposure Level (PEL), further soil-disturbing activities shall be completed by HAZWOPER-certified personnel. If arsenic is detected in the air sample at a concentration that is less than the OSHA PEL, • excavation can be completed by personnel that have received contaminant awareness training. 4. A health and safety plan (HASP) will be required to perform excavation within contaminated areas. The HASP shall be prepared in accordance with the requirements identified above. OSHA regulation 29 CFR Part 1910.120 includes the provision for Hazardous Waste Site Operations and Emergency Response (HAZWOPER) training, including a health and safety program, for employees working in hazardous waste cleanup areas. The City and contractors shall develop and be responsible for implementation of their own site-specific health and safety plan for site workers in accordance with these and any other applicable requirements. 5. A condition of no visible airborne dust shall be maintained at all times during construction, maintenance, and landscaping activities in contaminated areas. 6. Contaminated soil that is excavated can be loaded directly into trucks for transport to a subtitle D +� landfill under permit. Alternatively, soil can be stockpiled onsite in accordance with the instructions below. 7. Contaminated soil shall be segregated from non-contaminated soil and can be secured on-site by placing it either in 1 a designated stockpile area that is either lined or as halt/concretepaved, P g � ( ) g P� P covered by durable plastic sheeting and bermed to control runoff, or (2) in labeled roll-off containers, or other covered containers. Access to the secured soil will be restricted by fencing or other physical barriers to prevent unauthorized personnel from contacting the soil. On-site storage of soils shall be managed to comply with Best Management Practices for erosion and sediment control. rIr 8. DEQ will be informed in writing of any significant release of contaminated material. File No.4025-003-01 Page 3 GWENGINEERS/ April 11,2007 +rte rr 6.3 EROSION CONTROL am Personnel shall take appropriate steps to prevent the erosion of soil in and from contaminated areas. Erosion control methods my include one or more of the following: 1) installation of silt fence; 2) use of filter bags and/or fabric; 3) scheduling of activities to avoid rainy periods; 4) avoidance of construction activities in high risk areas such as the banks of Fanno Creek and 5) other methods that are necessary and appropriate. 6.4 SOIL STOCKPILE TESTING 1. Soil that is excavated from contaminated areas of the site shall either: 1) be treated as contaminated and disposed of as described in Section 6.5 or 2) be tested as described below to assess soil quality. 2. Stockpiled soil shall be tested at the frequency described below: • 0— 100 cubic yards of soil Minimum of 3 samples • 101 —500 cubic yards of soil Minimum of 5 samples • 501 — 1,000 cubic yards of soil Minimum of 7 samples • 1,001 —2,000 cubic yards of soil 10 samples+for each additional 500 cubic yards of soil 3. Samples shall be collected from stockpiled soil in general accordance with the most recently promulgated version of the U.S. Environmental Protection Agency's (EPA) "Test Methods for +• Evaluating Solid Waste, Physical/Chemical Methods, SW-846" 4. Samples shall be submitted to an Oregon-accredited analytical laboratory for analysis of arsenic by EPA Method 6010. rr� 6.5 DISPOSITION OPTIONS FOR SOIL 1. Soil that contains concentrations of arsenic less than 7 mg/kg shall be considered non- contaminated and can be re-used at the site or disposed of at a non-regulated facility. Soil that contains concentrations of arsenic exceeding 7 mg/kg shall be considered contaminated and must be disposed of at a Subtitle D facility. 2. Contaminated soil that is transported off site shall be disposed of at a Resource Conservation and Recovery Act (RCRA) Subtitle D municipal and/or non-hazardous waste landfill facility. Waste rr Management's Hillsboro Landfill is a local Subtitle D facility. 3. Transport and disposal of soil shall be in accordance with local, state and federal regulations. 4. Soil profiling will be required prior to disposal The City, as owner of the property, will be considered the hazardous material generator for arsenic-contaminated soil at the site. The City will not be considered the generator for hazardous substances that are a result of others' operations or negligence. 5. The City will be presented with waste authorization forms and bills of lading for City signature prior to the removal of any contaminated soil from the site. 7.0 WALL STREET EXTENSION AND ASSOCIATED IMPROVEMENTS The City plans to extend Wall Street across the southern portion of the site during summer 2007. During the roadway improvements, the City also plans to construct a driveway to private property located south File No.4025-003-02 Page 4 GWENGINEER� April 11,2007 Yltll ■r .,, of the library site; mitigate wetlands; extend the existing library parking area, restore a stream near the south edge of the site, and construct a stormwater retention pond. The following sections present contaminated soil management information specific to the planned Wall Street extension and associated „W improvements. 7.1 ROADWAY, DRIVEWAY,AND PARKING LOT IMPROVEMENTS wr Many of the planned roadway, driveway, and parking area improvements will be constructed over or in contaminated soil. Contaminated soil that underlies planned construction areas is shown on Figure 1. Geogrid or other landscaping fabric, which will serve as a future demarcation layer, should be placed directly over native soil in all areas where construction includes placement of at least 2 feet of fill (including soil, soil amendments and rock sand)or asphalt or concrete over contaminated soil. In cases where bark dust will be placed on top of contaminated soil, geogrid or other landscaping fabric should be placed over native soil. r Stripping of organic-rich surface soil and vegetation is not required in the roadway, driveway, and parking lot improvement areas where geogrid is utilized. Limited amounts of excavation of contaminated soil may be required in the roadway, driveway, and parking lot to construct utilities, culverts, and other purposes. Soil that is excavated from these areas should be handled in accordance with the recommendations presented in Section 6.0. wr 7.2 WETLAND MITIGATION The Wall Street extension project includes wetlands mitigation in the southern portion of the site. Wetland mitigation areas are shown on Schedule G of DeHaas and Associates, Inc. project plans. Wetland mitigation plans call for striping native soil and replanting selected areas with native wetland vegetation. All soil disturbing activities that occur during wetland mitigation activities should be conducted in accordance with the recommendations presented in Section 6.0. rw 7.3 STREAM RESTORATION A stream channel at the southern portion of the site will be restored/relocated during the Wall Street extension project. The stream restoration project includes the excavation of as much as approximately 5 feet of soil, removal of an existing culvert, placement of soil amendments, and landscaping. Soil in the +� southwest portion of the site in the vicinity of the proposed stream channel is contaminated, as shown on Figure 1. rri All soil that is excavated in contaminated areas during the stream restoration should be conducted in accordance with the recommendations presented in Section 6.0. aw Following excavation of the stream channel, samples should be collected to confirm that the levels of contaminants in the stream channel are less than or equal to DEQ Default Background Concentrations for soil (7 mg/kg) or are covered with sufficient imported non-contaminated soil or rock that stream water will not contact contaminated soil. Contaminated soil will likely be present in portions of the constructed stream banks. In contaminated portions of the site, native soil in stream banks must also be covered with: 1) landscape fabric or other City-approved material that is placed directly above native soil and 2) at least 2 feet of non-contaminated .r File No.4025-003-02 Page 5 GWENGINEER April 11,2007 rr rr 7.4 STORMWATER RETENTION POND The City plans to construct a water quality swale east of the parking area. The proposed swale will be approximately 2 to 3 feet deep, 120 feet long, and approximately 15 to 25 feet wide (finished dimensions). Contaminated will be encountered in the eastern portion of the swale, as shown on Figure 1. All soil that is excavated in contaminated areas during the swale construction should be conducted in accordance with the recommendations presented in Section 6.0. 7.5 RE-USE OF NATIVE SOIL Contaminated soil that is excavated during the planned construction activities can be re-used under the following conditions: • The contaminated soil shall be re-used in a portion of the site that currently contains contaminated soil (as shown on Figure 1); • The contaminated soil shall be placed below geogrid or other City-approved demarcation layer; • The contaminated soil shall not be placed in the flood plain of Fanno Creek and shall be protected from erosion; rrr • The contaminated soil shall be covered with asphalt or concrete pavement; and • The location of the re-used contaminated soil shall be documented. 8.0 CONTAMINATED SOIL VOLUMES The following table summarizes GeoEngineers' estimates of the volumes of contaminated soil that will be removed from the site during the planned improvements. The estimated volumes are based on information presented in "Geotechnical Investigation, Wall Street LID, Tigard, Oregon" (Shannon and Wilson, 2003), building plans by DeHaas and Associates, Inc (2006), and conversations with City personnel. Estimated Volume of Contaminated Material To ri Improvement Area Task Be Removed Assumptions Wall Street extension,west of Grading 200 cubic yards 2-foot excavation depth; 2700 Station 12+40 and east of non- square feet. contaminated soil Wetlands at east side of site Stripping and 210 cubic yards 1-foot stripping depth; 5,600 grading square feet. Constructed water quality Excavation 100 cubic yards 2-foot average excavation depth; 1,185 square feet. Stream restoration/relocation Stripping and 2,030 cubic yards 2.5-foot average excavation Excavation depth; 18,600 square feet rr (west of culvert). 2—foot average excavation depth; 4,150 square feet(east of culvert). File No.4025-003-02 Page 6 GWENGINEERS April 11,2007 urr 9.0 LIMITATIONS This letter has been prepared for the exclusive use of the City of Tigard and their authorized agents. No other party may rely on the product of our services unless we agree in advance and in writing to such reliance. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted environmental science practices in this area at the time this letter was prepared. No warranty or other conditions, express or implied, should be understood. rI This plan was developed based on our understanding of conditions at the property. No study can wholly eliminate uncertainty regarding environmental conditions at a property. There is always a potential that areas of contamination exist that were not identified during the past studies. Further evaluation of such potential would require additional research, subsurface exploration, sampling and/or testing. wr rI� rir �Ir r. .>r rr File No.4025-003-02 Page 7 GWENGINEERS/ April ll,2007 +rte PA4\4025003\02\CAD\Figure 1.dwg CWB:MWJ 04/11/07 3 • �.` N 9 W#E ��� • • �.ti�Y S • i IN ( 1 70 0 70 1 I Feet • 1# r I 1' 11 I I•i • e • • • _ ��� 1 1 ( /I I Approximate Northern Site Boundary Area \ I \ ti .. a` // AW O �, I� � �i I • Pine Tree Area l I I >r' �; I S•r s >�t � � I I I �; t Oj � � • � • Central g 1i Tree Area o t IW 1 a � I 11 � §et�i I' iii�igi .� • 1 4 �atga ll,i', ii 1 D- ( Y �foJn=:+ISS lNJ" •.]G I —' im 1 /,��'' I LYMo+ /J'J9'/7• ..0 , f J / 1 I A + 108.I3' _ c i Southern., Area I i z� t t. it cs ..................:::... .. _ F .� .. .............. ... _. i0 w � I :::.w::::f:���:':•:: • ���� --� - Proposed Road t ... .. N .. ........ G11 i? ..... Legend: O 6 Area of soil containing arsenic above (7mg/kg) based on testing results and site conceptual model. Requires O special handling. r' Area of remaining soil containing arsenic (>7-g/kg) '91 that is capped with pavement and/or at least 2 feet of clean fill. Requires special handling. 111 I g 20 Contaminated Soil Areas Nates: Tigard Library - Soil Management Plan 1.The locations of all features shown are approximate. Tigard, Oregon 2.This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document.GeoEngineers,Inc.can not guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers,Inc.and will serve as the official record of this communication. G EO E N G I N E E R Figure II Reference:Base Drawing dated 10/2006,provided by Hahn and Associates. ro'" mn� Onna NNW" NNW" Emm" WNEM9 ��