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* HAGER-RICHTER GEOSCIENCE, INC. SEISMIC REFRACTION SURVEY RUETGERS-NEASE SITE STATE COLLEGE, PENNSYLVANIA Prepared for: SMC Environmental Services Group 900 West Valley Forge Road P.O. BOX 859 Valley Forge, Pennsylvania 19482 Prepared by: Hager-Richter Geoscience, Inc. 8 Industrial Way, Unit D10 Salem, New Hampshire 03079 File 90J12 October, 1990

HAGER-RICHTER GEOSCIENCE, INC.HAGER-RICHTER GEOSCIENCE, INC. Seismic Refraction Survey Ruetgers-Nease Site State College, PA File 90J12 we use a combination of geophone spacing and

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*HAGER-RICHTERGEOSCIENCE, INC.

SEISMIC REFRACTION SURVEYRUETGERS-NEASE SITE

STATE COLLEGE, PENNSYLVANIA

Prepared for:

SMC Environmental Services Group900 West Valley Forge RoadP.O. BOX 859Valley Forge, Pennsylvania 19482

Prepared by:

Hager-Richter Geoscience, Inc.8 Industrial Way, Unit D10Salem, New Hampshire 03079

File 90J12October, 1990

1 HAGER-RICHTERI GEOSCIENCE, INC.

CONSULTANTS IN GEOLOGY & GEOPHYSICS8 INDUSTRIAL WAY - 010

SALEM, NEW HAMPSHIRE 03079TELEPHONE (603) 893-9944 / (617) 647-1546

FAX (603) 893-8313

November 16, 1990File 90J12

Mr. Bryan D. SmithSMC Environmental Services Group900 West Valley Forge RoadP.O. Box 859Valley Forge, PA 1942

Dear Mr. Smith:

Enclosed are five (5) copies of our report entitled "SeismicRefraction Survey, Ruetgers-Nease Site, State College,Pennsylvania."

Please contact us if you have any questions or need furtherinformation.

Sincerely yours,HAGER-RICHTER GEOSCIENCE, INC.

Jutta L. HagerPrincipal

AR302W8

HAGER-RICHTERGEOSCIENCE, INC.

Seismic Refraction SurveyRuetgers-Nease SiteState College. PA File 90J12

0. EXECUTIVE SUMMARY

In October, 1990, Hager-Richter Geoscience, Inc. conducted aseismic refraction survey at the Ruetgers-Nease Chemical CompanySite in State College, Pennsylvania for SMC Environmental Serv-ices Group of Valley Forge, Pennsylvania.

The survey area is clear and open; the surface slopes gentlytoward the northwest. The objective of the survey was to deter-mine bedrock depths at the Site, with the goal of using changesin bedrock topography to locate a thrust fault believed to dividethe Site.

The seismic refraction survey consisted of 5 lines ofprofile totaling 920 linear feet. The seismic refraction surveydetermined: (1) the probable location of the thrust fault divid-ing the Site; (2) the presence of two distinct seismic layersalong the survey lines: (A) a low velocity layer, interpreted tobe uncompacted, unsaturated sediments, and (B) a higher velocitylayer interpreted to be bedrock; and (3) a bedrock depth beneaththe survey lines ranging from 8 to 27 feet below ground surface.

SR3Q2i*09

HAGER-filCHTERGEOSCIENCE, INC.

Seismic Refraction SurveyRuetgers-Nease SiteState College. PA File 90J12

TABLE OP CONTENTS

0. Executive Summary i

l. Introduction 1

2. Equipment and Procedures 12.1 General 12.2 Site Specific 3

3. Results and Discussions 33.1 General 33.2 Seismic Profiles 33.3 Bedrock Depths 43.4 Evidence for a Thrust Fault 4

4. Conclusions 5

TABLES AND FIGURES

Table 1. Relationship between Velocity of Seismic Wavesand Geologic Materials Observed at the Ruetgers-Nease Site.

Table 2. Seismic Refraction Results.

****

Figure 1. Location of the Site.

Figure 2. Location of Seismic Lines.

Figure 3. Seismic Line SL1.

Figure 4. Seismic Line SL2.

Figure 5. Seismic Line SL3.

Figure 6. Seismic Lines SL4 and SL5.

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GEOSCIENCE, INC.Seismic Refraction SurveyRuetgers-Nease SiteState College. PA File 90J12

1. INTRODUCTION

In October, 1990, Hager-Richter Geoscience, Inc. conducted aseismic refraction survey for SMC Environmental Services Group ofValley Forge, Pennsylvania, at the Ruetgers-Nease Chemical Com-pany Superfund Site in State College, Pennsylvania. The locationof the Site is shown in Figure 1.

The Site is an active industrial facility that lies alongthe southeast side of a valley. It is clear and open, slopinggently to the northwest. Most of the site is grassy, but thereare several paved roads and a set of railroad tracks.

The objective of the seismic refraction survey was to locatea thrust fault that SMC believes divides the Site.

Hager-Richter personnel Jeffrey Reid and David Petroy wereon Site on October 10 and 11, 1990 to conduct the seismic refrac-tion survey. The field operations were coordinated with and ob-served by Mr. Byran Smith and Mr. William Randall of SMC. Thelocations of all seismic refraction lines were selected by SMC.The data were analyzed at our offices in Salem, New Hampshire.Original data and field notes reside in the Hager-Richter filesand will be retained for a minimum of three years.

2. EQUIPMENT AND PROCEDURES

2 . 1 General

2.1.1 Field Work . We used a 24-channel Bison Model 9024Digital Instantaneous Floating Point Stacking Seismograph to per-form the seismic refraction survey. The Model 9024 is a "stateof the art" microprocessor controlled instrument that recordsdata digitally and on paper seismograms. The paper records areused in the field to verify the quality of the data and to backupthe digital data. The stored data are transferred to a laptopcomputer at the end of each field day for storage, backup, andfuture data processing.

The seismograph was coupled to two 12 -element seismic spreadcables for a total of 24 geophones. The geophone spacing isusually selected (or verified) in the field. For most projects,

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HAGER-RICHTERGEOSCIENCE, INC.

Seismic Refraction SurveyRuetgers-Nease SiteState College, PA File 90J12

we use a combination of geophone spacing and seismic source off-sets sufficient to record arrivals from bedrock and the watertable.

Seismic energy is provided by a 12-lb sledge hammer strikinga steel base plate, a 70-lb weight drop, or a Betsy seisgun. TheBetsy seisgun uses a shotgun blank as the seismic source and isnot classified as a weapon or explosive under Federal regula-tions. The number of stacks per shot point is variable, and thequality of the stacked seismic signal for each shot point isverified in the field with the paper record. Seven shot pointsare. typically used for each 24-geophone spread — one shot offeach end of the cable, one shot at each end of the cable, one inthe middle, and a symmetrical pair of intermediate shots. Thisconfiguration provides reversed profiles. Shot points (andgeophone locations, if necessary) are flagged in the field.

2.1.2 Data Analysis. The seismic data are analyzed usingthe Generalized Reciprocal Method (GRM) of seismic refraction in-terpretation. GRM has several advantages over other interpreta-tion methods for seismic refraction such as the Time-Intercept orCrossover-Distance methods. GRM allows for some variation in thesurface topography as well as lateral variation in the seismicvelocity of the upper layers. The method uses a principle ofmigration whereby the refractor need only be planar over a shortdistance, thus allowing the calculation of depth to an undulatinginterface. In addition, GRM is relatively insensitive to dipangles as high as 20°, unlike most other methods that can be sen-sitive to dips as low as 5°. GRM also allows for the calculationof depth below each geophone instead of below only the shotpoints as in the Time-Intercept and Crossover Distance methods.The GRM program that we use for data analysis contains severalinternal tests for data consistency.

The results are used to construct an interpreted velocityprofile of the subsurface for each seismic line. The velocitiesof seismic waves are strong functions of the types of geologicmaterial through which they pass. One can thus infer the generalsubsurface stratigraphy from the velocities exhibited.

A common misconception about the seismic refraction methodis that one cannot detect layers of lower velocity material un-derlying higher velocity material, a common situation instratified sediments. If present and undetected, jtl^Lwer

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*9 * HAGER-RICHTERGEOSCIENCE, INC.

Seismic Refraction SurveyRuetgers-Nease SiteState College. PA File 90J12

velocity layers can cause large errors in the thickness calcu-lated for the various layers. However, the GRM techniqueprovides for the detection of such low-velocity layers, and, moreimportantly, provides correct depths to refracting horizons belowany low-velocity layers that may be present. Typical uncer-tainties in depths determined seismically are +/- 10% or 2 feet,whichever is larger.

2.2 Site Specific

Five seismic profiles, for a total of 8 spreads, were run atthe Ruetgers-Nease Chemical Company Site. Each spread consistedof two 12-element seismic cables with 24 geophones. A geophonespacing of 5 feet was used, so that each spread was 115 feetlong.

Energy for the seismic refraction survey was provided byhitting a steel baseplate with a 12-pound sledgehammer. Theseismograph recorded data for 100 milliseconds after each shot.

3. RESULTS AND DISCUSSION

3.1 General

The locations of the seismic refraction profiles are shownin Figure 2. The base map was provided by SMC. All the seismiclines except Seismic Line SL4 were run at the locations plottedon base map provided. Seismic Line SL4 was offset to the south-west from its original location to avoid a set of railroad tracksand a drainage ditch. The five profiles totaled 920 feet.

SMC provided copies of logs for five deep monitoring wellsin the vicinity of our seismic refraction lines. Monitoringwells 6, 11, and 25 are located along our seismic lines. Theirlocations are plotted in figures 3, 5, and 6.

3.2 Seismic Profiles

Table 1 shows the relationship between the velocities andtypes of materials observed at the Ruetgers-Nease Site. Figures3 through 6 are profiles showing depths to refracting layers.Elevations of these layers are not given, since no surface eleva-tions were made provided. On the basis of theseismic layers are present. The more shallow ]

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HAGER-RICHTERGEOSCIENCE, INC.

Seismic Refraction SurveyRuetgers-Nease SiteState College. PA File 90J12

to be unsaturated sediments (including fill in some locations),has a velocity ranging from 1300 to 1900 feet per second (fps).The lower layer, interpreted to consist of bedrock, ranges indepth from 8 to 27 feet, and in velocity from 9000 to 13300 fps.Water table is known to occur at depths greater than 50 feet, andwould not be detected by seismic refraction.

The presence of a hidden layer, i.e., a lower velocity layerunderlying higher velocity material, was detected beneath seismiclines SL4 and SL5. GRM allowed us to correct for this hiddenlayer and calculate a corrected depth to bedrock, using anaverage overburden velocity of 2500 fps, as shown in Figure 6.Both the bedrock depth and the existence of soil beneath thinlayers of fragmented rock were corroborated by data from MW-6.

3.3 Bedrock Depths

The depths to bedrock along the seismic profiles are listedin Table 2. The table shows that bedrock is deepest beneathseismic lines SL4 and SL5 and most shallow beneath seismic linesSLl and SL3. Bedrock tends to become more shallow toward thesoutheast. There is a gap in bedrock information along SeismicLine SL2 because the spread cable could not be laid across ClydeAvenue, an active road.

The seismic refraction results correlate well with theboring data for the Site. MW-11, along Seismic Line SL3, showsbedrock at 8 feet; the seismic depth at that point is 9 feet.MW-25, at the end of Seismic Line SLl, shows bedrock at 11 feet;the seismic depth is 13 feet. MW-6, along Seismic Line SL5,shows bedrock at 25 feet; the seismic depth is 26 feet.

3.4 Evidence for a Thrust Fault

Evidence for the existence of a thrust fault along our seis-mic profiles exists as several relatively smooth, planar bedrockfeatures dipping at low angles toward the northwest. Corrobora-tion of this evidence comes from boring MW-11,, drilled into oneof these possible fault planes along Seismic Line SL3 and loggedas possibly encountering a fault.

From the seismic profiles, the fault plane appears to liebetween 1+00 and 1+25 along Seismic Line SLl, 0+20 and 0+60 alongSeismic Line SL2, 0+75 and 1+10 along Seismic Line SL3, and 0+20and 0+60 along Seismic Line SL5. It forms a distinct surface

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HAGER-RICHTERv GEOSCIENCE, INC.

Seismic Refraction SurveyRuetgers-Nease SiteState College. PA File 90J12

dipping to the northwest at angles ranging from approximately 5°to 11°. The higher dip angle along Seismic Line SLl may indicatethat the fault plane along this profile represents a differentsliver than the one traced out along the other seismic profiles.The inferred location of the thrust fault is shown as a dashedline in Figure 2.

4. CONCLUSIONS

The seismic refraction survey conducted October 10 and 11 atthe Ruetgers-Nease Chemical Company Superfund Site determined:(1) the probable location of the thrust fault dividing the Site;(2) the presence of two distinct seismic layers along the surveylines: (A) a low velocity layer, interpreted to be uncompacted,unsaturated sediments, and (B) a higher velocity layer inter-preted to be bedrock; and (3) a bedrock depth beneath the surveylines ranging from 8 to 27 feet below ground surface.

- 5&R3Q2MS

HAGER-RICHTERGEOSCIENCE. INC.

Seismic Refraction SurveyRueitgers-Nease SiteState College, PA File 90J12

U1

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Figure 1. Location of the Site.

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HAGER-RICHTERGEOSCIENCE, INC.

Seismic Refraction SurveyRuetgers-Nease SiteState College. PA File 90J12

TABLE 1. RELATIONSHIP BETWEEN VELOCITYOF SEISMIC WAVES AND GEOLOGIC MATERIALSOBSERVED AT THE RUETGERS-NEASE SITE

VELOCITY TYPE OF MATERIAL(Ft/Sec)

1300-1900 Soft & uncompacted low-densitymaterials including fill andunsaturated soil, silt, sand,gravel, and cobbles« Includessoil-filled voids in bedrock.

9000-13300 Bedrock, consisting of limestone anddolomitic limestone. Contains thewater table.

Seismic Refraction SurveyRuetgers-Nease SiteState College. PA File 90J12 HAbtH-—————— ———————— GEOSCIENCE, INC.

TABLE 2. SEISMIC REFRACTION RESULTS

SEISMIC LINE GEOPHONE LOCATION BEDROCK DEPTH

SL 1 0+00 110+05 110+10 110+15 100+20 90+25 90+30 90+35 80+40 80+45 90+50 100+55 110+60 110+65 110+70 110+75 120+80 120+85 110+90 120+95 111+00 121+05 131+10 141+15 151+20 171+25 171+30 171+35 181+40 181+45 191+50 181+55 181+60 181+65 181+70 171+75 171+80 171+85 171+90 171+95 172+00 172+05 17

2«5 162+20 152+25 142+30 13

Seismic Refraction SurveyRuetgers-Nease SiteState College. PA File 90J12

TABLE 2. SEISMIC REFRACTION RESULTS (CONT.)

SL 2 0+00 ND*0+05 220+10 220+15 210+20 200+25 210+30 210+35 220+40 220+45 230+50 230+55 240+60 250+65 240+70 220+75 210+80 210+85 210+90 200+95 191+00 181+05 181+10 201+15 20

GAP DUE TO CLYDE AVENUE1+55 ND *1+60 171+65 171+70 181+75 191+80 191+85 191+90 201+95 182+00 192+05 192+10 192+15 192+20 182+25 172+30 162+35 16

2+50 172+55 172+60 182+65 182+70 ND

* Depth not determined.

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Seismic Refraction Survey ______Ruetgers-Nease site HAGER-RICHTER

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state conaqe, PA m« 90J12 GEOSCIENCEINC.

TABLE 2. SEISMIC REFRACTION RESULTS (CONT.)

SEISMIC LINE GEOPHONE LOCATION BEDROCK DEPTH

SL 3 0+00 80+05 80+10 80+15 90+20 90+25 80+30 80+35 80+40 80+45 80+50 80+55 80+60 80+65 80+70 80+75 80+80 90+85 100+90 100+95 111+00 111+05 121+10 121+15 111+20 101+25 101+30 101+35 101+40 111+45 121+50 131+55 131+60 131+65 131+70 131+75 131+80 131+85 131+90 131+95 132+00 132+05 132+10 142+15 142+20 152+25 152+30 15

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Seismic Refraction SurveyRuetgers-Nease Site UAO'CD DIPUTCDstate coiieqe, P. ,U. GEOSCENCE INC.

TABLE 2. SEISMIC REFRACTION RESULTS (CONT.)

SEISMIC LINE GEOPHONE LOCATION BEDROCK DEPTH

SL 4 0+00 210+05 210+10 210+15 220+20 230+25 230+30 220+35 220+40 220+45 220+50 220+55 220+60 230+65 230+70 230+75 230+80 230+85 230+90 230+95 231+00 221+05 221+10 221+15 21

SL 5 0+00 ND *0+05 ND0+10 230+15 230+20 230+25 240+30 240+35 260+40 260+45 , 260+50 260+55 270+60 270+65 270+70 260+75 250+80 250+85 260+90 260+95 261+00 261+05 261+10 251+15 25

* Depth not determined.