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HomeMy WebLinkAbout38022; Pine Park; Pine School Geophysical Survey Report; 2002-04-03>X:-EX.T^XLAiy^AA/lA?2^^^ Geotechnical and Environmental Sciences Consultants April 3, 2002 ProjectNo. 104567002 Mr. Keith Beverly City of Carlsbad 1200 Carlsbad Village Drive Carlsbad, Califomia 92008 Subject: Geophysical Survey Report Pine Elementary School 3333 Harding Street Carlsbad, Califomia Reference: "Phase I Environmental Site Assessment Update and Hazardous Building Materi- als Survey, Pine Elementary School, 3333 Harding Street, Carlsbad, Cahfomia," prepared by Ninyo & Moore, dated Febmary 4, 2002. INTRODUCTION This letter report documents the fmdings of a geophysical survey performed at the Pine Elemen- tary School, located at 3333 Harding Street, in Carlsbad, Califomia (Figure 1). Work was conducted in general accordance with oiu: proposal dated Febmary 22 (revised March 6), 2002, and your authorization to proceed. BACKGROUND The fmdings of Ninyo & Moore's referenced Phase I Environmental Site Assessment Update (ESAU) for the subject site stated the following: "The fuel source for the former boiler at the site has not been identified. In addition, a black sticky substance was noted in a condidt in the boiler room during the site reconnaissance. The fuel source for a possible second boiler on the site has not been identified. Further in- vestigation should be conducted to determine whether a UST or underground fuel supply lines remain in the vicinity of the boiler room, and in the vicinity of the southerly classroom building, where the second boiler may have been located. " 5710 Ruffin Road « San Diego, Califomia 92123 » Phone (858) 576-1000 • Fax (858) 576-9600 San Diego « Irvine " Ontario ••• Los Angeles Oakland » Las Vegas « Salt Lake City " Phoenix City of Carisbad April 3, 2002 3333 Harding Street, Carisbad Project No. 104567002 OBJECTIVES The objective of this geophysical survey was to evaluate the areas in the vicinity of the former boiler and the possible second boiler room for the presence of an underground storage tank (UST) or underground fuel lines. GEOPHYSICAL SURVEY ACTIVITIES On March 12, 2002, Ninyo & Moore contracted Subsurface Surveys to perform a geophysical survey in the vicinity of the former boiler room, and in the vicinity of the southerly classroom building where a second boiler may have been located (Figure 2). A brief description of the geo- physical methods applied is contained in a Geophysical hivestigation Report, prepared by Subsurface Surveys, dated March 19, 2002. A copy ofthe report is attached. Survey activities were performed in the interior of the former boiler room and in the exterior ar- eas surrounding the room (Figure 2). Several underground pipes and in-service utilities (i.e., natural gas lines, electrical lines, and telephone lines) were noted in this area. An unknown un- derground line was noted to trend away from the boiler room, and end in an area to the west of the boiler room, near the concrete sidewalk. Several unknown imderground lines were also noted beneath the concrete sidewalk to the northwest of the boiler room. However, evidence suggesting that these lines were former underground fuel supply lines was not noted. Also, the conduit lo- cated inside the boiler room, as noted by the Phase I ESAU, did not appear lead to any subsurface stmctures. This conduit may have been a sewer clean-out. Furthermore, the geophysi- cal survey did not indicate the possible presence of USTs in this area. An interview conducted for the Phase I ESAU indicated that a second boiler room may have been located near the offices in the southerly classroom building. During the geophysical survey, two empty maintenance/storage rooms were noted in the southwestem portion of this building. Other areas in the vicinity ofthe former offices appeared to have been used as classrooms or of- fices only. Based on our observations and on the previous interview, it was Ninyo & Moore's opinion that the two maintenance/storage rooms were the most likely location for a boiler room 4567002geophysi calj. doc City of Carisbad April 3, 2002 3333 Harding Street, Carlsbad ProjectNo. 104567002 in the southerly classroom building. However, the geophysical methods applied did not suggest the presence of a UST in the nearby exterior areas. FINDINGS AND OPINIONS The results of the geophysical survey did not indicate the potential presence of a UST or associ- ated underground fuel lines in the nearby vicinity of the former boiler room or in the nearby vicinity of the second suspected boiler room. However, several unknown underground hnes were noted in the vicinity of the former boiler room. Even though there are no apparent UST-related features (e.g., vent pipes or fill ports) in these areas, a more clear indication of the subsurface conditions may be obtained through subsurface excavation. Should you desire such an evalua- tion, a detailed scope of work will be provided upon request. LIMITATIONS The environmental services described in this report have been conducted in general accordance with current regulatory guidelines and the standard-of-care exercised by environmental consultants performing similar work in the project area. No warranty, expressed or implied, is made regarding the professional opinions presented in this report. Please note that this study did not include an evaluation of geotechnical conditions or potential geologic hazards. This document is intended to be used only in its entirety. No portion ofthe document, by itself, is designed to completely represent any aspect of the project described herein. Ninyo & Moore should be contacted if the reader requires any additional information or has questions regardmg the content, interpretations presented, or completeness ofthis document. Our findings and opinions are based on an analysis of the observed site conditions and the refer- enced Uterature. It should be imderstood that the conditions of a site could change with time as a result of natural processes or the activities of man at the subject site or nearby sites. In addition, changes to the applicable laws, regulations, codes, and standards of practice may occur due to gov- emment action or the broadening of knowledge. The fmdings of this report may, therefore, be invalidated over time, in part or in whole, by changes over which Ninyo & Moore has no control. 4567002geophysical_L doc City of Carlsbad 3333 Harding Street, Carlsbad April 3, 2002 ProjectNo. 104567002 This report is intended exclusively for use by the chent. Any use or reuse of the findings, conclu- sions, and/or recommendations of this report by parties other than the client is undertaken at said parties' sole risk. We appreciate the opportunity to be of service to you on this project. Should you have any ques- tions, please contact the undersigned at your convenience. Sincerely, NINYO & MOORE Travis L. Stravasnik Senior Staff Environmental Scientist TLS/PDC/SB/kmf Stephan A. Beck, C.E.G., HG., R.E.A. II Manager, Environmental Sciences Division Attachments: Figure 1 - Site Location Map Figure 2 - Site Plan Subsurface Surveys' Geophysical Investigation Report Distribution: (1) Addressee 4367002geophysicaIJ.doc REFERENCE: 2001 THOMAS GUIDE FOR SAN DIEGO COUNTY, STREET GUIDE AND DIRECTORY SITE LOCATION MAP PINE ELEMENTARY SCHOOL 3333 HARDING STREET CARLSBAD, CALIFORNIA C PROJECTNO. DATE ^ t 104567002 4/02 J c FIGURE 1 \ APPROXIMATE AREA OF GEOPHYSICAL SURVEY SITE APPROXIMATE AREA OF SUSPECTED BOILER ROOM \ LEGEND ^— Fence ~ ' ' ~~ Site boundary APPROXIMATE AREA OF GEOPHYSICAL SURVEY \ FOOD SERVICE BUILDING PARKING \ Not to Scale SITE PLAN PINE ELEMENTARY SCHOOL 3333 HARDING STREET CARLSBAD, CALIFORNIA J /PROJECT NO. DATE ^ > V 104567002 4/02 J FIGURE ) 91 S HioWay 101 Siiitp om P O Bny 1157. Snlana Reach C A 92075 Telephone: (858) 481-8949 Facsimile: (858) 481-8998 E mail: geop@subsurfacesurveys.com March 19, 2002 Ninyo & Moore Invoice/Project No. 02-096 5710 Ruffin Road San Diego, CA 92123 Attn: Travis Stravasnik Re: Geophysical Investigation Report, Pine Elementary School, Carisbad, Ca This report is to present the resuhs of our geophysical surveys carried out over portions ofthe subject site located at 3333 Harding Street, in Carlsbad, Califomia figure 1), on March 12, 2002. Two separate portions ofthe campus were selected were boiler rooms may have been present in the past. These areas were targeted because the possibility of UST's associated with boiler rooms was suspected. The purpose of our survey was to scan the vicinity of the former boiler rooms in an attempt to locate and identify, insofar as possible, tanks and associated piping if they exist. A combination of electromagnetic induction, EM, magnetometry, and ground penetrating radar, GPR, were applied to the search (Figure 2). A utility locator with hne tracing capabilities was also brought to the field and used where risers existed onto which a signal could be impressed and traced. Muhiple methods were utilized because each instmment senses different material properties ofthe ground and buried objects. At any given site the situation, geologic and cultural, may be such that one or more ofthe instmments may record excessive "noise", the ground may not provide sufficient contrasts, or there may be overiapping anomaUes, for a given instmment to be effective. Summarily stated, there are generally instmmental limits and interpretational impediments. Consequently, we cannot guarantee that all problems in all cases will be solved with geophysical surveying; however, our interpretation will be based on the best reconciUation ofthe several data sets acquired. Nevertheless, we can, and do, certify that we own state-of-the-art instmments, we are trained and experienced, are committed to acquiring the best data sets possible, and will bring to bear our expertise in formulatmg the interpretation. S^nrvpy DRsign -The mstmments were traversed on random survey lines, which were designed to systematically screen the outside areas adjacent to the two former boiler rooms. A Geonics model EM61 instmment, and a Fischer M-Scope, was used for the EM sampling. A Sensors and Softwares Noggin Ground Penetratmg Radar unit produced the radar images. The magnetic gradiometer was a Schonstedt GA-52, and a Metrotech 9890 utility locator rounded out the tools applied. Rripf npsr.Hptinn nf tbp Gmphy^^ral MpitfinHs Applied - The EM61 instmment is a high resolution, time- domain device for detecting buried conductive objects. It consists of a powerful transmitter that generates a pulsed primary magnetic field when its coils are energized, which induces eddy currents in nearby conductive objects. The decay of the eddy currents, following the input pulse, is measured by the coils, which in turn serve as receiver coils. The decay rate is measured for two coils, mounted concentrically, one above the other. By making the measurements at a relatively long time interval (measured in milliseconds) after termination of the primary pulse, the response is neariy independent of the electrical conductivity of the ground. Thus, the instmment is a super-sensitive metal detector. Due to hs unique coil arrangement, the response curve is a single well-defined positive peak directly over a buried conductive object. This facilitates quick and accurate location of targets. The magnetic gradiometer has two flux gate magnetic fixed sensors that are passed closely to and over the ground. When not in close proximity to a magnetic object, that is, only in the earth's field, the instmment emits a sound signal at a low frequency. When the mstmment passes over a buried iron or steel object, so that locally there is a high magnetic gradient, the frequency of the emitted sound increases. The frequency is a function of the gradient between the two sensors. The Une locator is used to passively detect energized high vohage electric Imes and electrical conduit (50- 60 Hz), VLF signals (14-22 kHz), as well as to actively trace other utihties. Where risers are present, the utility locator transmitter can be connected directly to the object, and a signal (9.8-82 kHz) is sent traveling along the conductor, pipe, conduit, etc. In the absence of a riser, the transmitter can be used to impress an input signal on the utility by mduction. In either case, the receiver unit is tuned to the input signal, and is used to actively trace the signal along the pipe's surface projection. The GPR instmment beams energy into the ground from hs transducer/antenna, m the form of electromagnetic waves. A portion of this energy is reflected back to the antenna at a boundary in the subsurface across which there is an electrical contrast. The instmment produces a continuous record of the reflected energy as the antenna is traversed across the ground surface. The greater the electrical contrast, the higher the ampUtude of the retumed energy. The radar wave travels at a velochy unique to the material properties of the ground bemg investigated, and when these velochies are known, the two- way travel times can be converted to depth. The depth of penetration and image resolution produced are a function of ground electrical conductivity and dielectric constant. Findings anH rnndnsinns - Interpretation took place in real time as the surveys progressed. Accordingly, the findings of our investigation were documented by the geophysical crew, primarily using digital photography (Figure 3). Local conditions were reasonably favorable at these sites, and the resuhs produced appear generaUy definitive. Tanks do not appear to have been detected within the search areas shown on Figure 3. Most of our efforts were focused on the former boiler room area shown in the bottom photograph. Here, a number of pipes and utilities (primarily in service) were detected and deUneated v^th marking paint. The area beneath the sidewalk on the west side of the building, m particular, was found to contain several pipes some of which appeared to terminate abmptly. Although the data does not support the existence of tanks for this area it is possible that the response from the detected pipes could mask an object buried beneath the level of the pipes. Subsurface Survey's professional personnel are trained and experienced and have completed thousands of projects since the companies inception in 1988. It is our policy to work diligently to bring this training and experience to bear to acquire quality data sets, which in turn, can provide clues useful in formulating our interpretations. Still, non-uniqueness of interpretations, methodological limitations, and non-target interferences are prevailing problems. Subsurface Surveys makes no guarantee either expressed or implied regarding the accuracy ofthe interpretations presented. And, in no event will Subsurface Surveys be liable for any direct, indirect, special, incidental, or consequential damages resulting from data sets, mark-outs and interpretations presented herewith. All data acquired in these surveys are in confidential file in this office, and are available for review by your staff, or by us at your request, at any time. We appreciate the opportunity to participate in this project. Please call, if there are questions. Lawrence J. Favilla, GP 969 Senior Geophysicist T Oceanside i.-'^k i 78 r Oqeanside ,>i&?[| Pacific Ocean l@2D0l] Mcrosoft;Con>: and/or.it3iSUDPliers: /!(l nahts:reservedi: jm!L. 9 Laquna Dr Pine Elementary School 3333 Harding St Carlsbad, CA 92008 lIsiiT' <3> or . TatTK A :4S21J Q tr.. O FIGURE 1 FIGURE 2