GEOLOGY Local Geology Local geologic mapping shows the site underlain by Goble Volcanics consisting of basalt and andesite, with basalt breccia, volcanic conglomerate, and interbedded siltstone and pyroclastics (Phillips, 1987). The mapping also shows lahar deposits for Mount Saint Helens in the general vicinity. We observed an outcrop of what appears to be Goble Volcanics ±400 feet east of the site and BH-1 encountered pyroclastics consistent with the Goble Volcanics. Unstable slopes are relatively common in areas underlain by the siltstone and pyroclastic units of the Goble Volcanics. The site is outside the Washington DNR and Fiksdal landslide mapping areas (Wegmann, 2006; Fiksdal, 1973). The explorations encountered colluvial clay and silt with rock fragments, followed by residual soil composed of silty clay with rock fragments and weathered rock consistent with the anticipated weathering products of bedrock shown on the local geologic mapping. 2012 SUBSURFACE INVESTIGATION An additional exploratory borehole (BH-2) was drilled on September 14, 2012, using a truck-mounted, CME 75 drill rig with mud-rotary drilling techniques. BH-2 was drilled to 33.5 feet below the pavement in the eastbound travel lane of Kalama River Road. The approximate location of BH-2 is shown on Figure 2. The boring was sampled with a split-spoon sampler at 5-foot intervals to 20 feet. From 25 feet to 31.5 feet, continuous samples were obtained by driving a California (2½-inch diameter sampler) and a split-spoon sampler. Disturbed 1-inch samples were obtained with a split-spoon in general accordance with Standard Penetration Test (SPT) and Split-Barrel Sampling of Soils (ASTM D1586). The SPT provides an indication of the relative stiffness or density of soils. While blow counts from the California sampler are not representative of SPT testing, the larger sample volume obtained using this method allows for better characterization of the soil. The boring was continuously logged by an FEI engineer. The collected samples were sealed to avoid moisture loss, and transported to the FEI office for further examination and potential testing. The final log (Appendix A) was prepared based on a review of the field log, the results of laboratory testing, and an examination of the soil samples in the FEI office. The boring log for BH-1 is also included in Appendix A. INSTRUMENTATION Piezometer and Data Logger A piezometer equipped with a Level Troll 300 automated data logger was installed in BH-2. The data logger records temperature and ground water levels at Kalama River Road, MP 9.16 Landslide June 6, 2013 Geotechnical Investigation Project 212-2-018 Cowlitz County, Washington 2. Cowlitz County, Department of Public Works

12-hour intervals. Continuous monitoring allows for observation of water level fluctuation. Short-term peak water levels are often generated during storm events and may be missed during periodic, manual monitoring. The piezometer consists of ±1-inch PVC casing with a 5-foot section of machine slots from ±25 to 30 feet below the ground surface. The annular space around the slotted section of casing was backfilled with Colorado Silica Sand. Above the sand, bentonite chips capped the installation to 2 feet below the ground surface. The installation is protected with an 8-inch diameter, flush Sherwood monument set in concrete. Once the monument was set, the Level Troll 300 was attached to the bottom of the locking cap and lowered to ±30 feet below the ground surface. Monitoring The data logger was programmed to record the water level two times per day. FEI downloaded the data following the winter rains to observe the fluctuation in ground water. The results of the monitoring from September 15, 2012 to April 29, 2013 are included in Figure 1B (Appendix B). SITE CONDITIONS Geotechnical Field Observations FEI visited the site on September 14, 2012, to map landslide features in and adjacent to the slide area. The mapping was performed using cloth tape and hand clinometer and the results of the field mapping were transferred to the survey base map provided by Cowlitz County (Figure 2). The mapping extended from Greenwood Road above Kalama River Road to the private drive at the base of the slope and laterally beyond the observed slide. A 125-foot long segment of Kalama River Road is cracked and depressed 4 to 6 inches. A bowl-shaped depression on the uphill side of the road is wet year round. A culvert located near the center of the landslide area drains the wet area above the road. A steep, riprap-covered embankment slope extends 25 feet downslope of the road. Two low areas were identified as the lateral extent of the slide. The two low areas merge 200 feet below the road. We interpreted this area to be the lower extent (toe) of the landslide. A private drive is located 50 feet farther down the slope. The landslide mapping is shown on Figure 2. Subsurface Conditions BH-2 encountered a pavement section of ±1.5 feet of asphaltic concrete (AC) over ±6 inches of base rock aggregate, underlain by medium stiff sandy clay with trace gravel (fill) to 10 feet. The fill is underlain by medium stiff to soft sandy clay with trace gravel to clayey silt with some sand and gravel (colluvium) to 27 feet. The colluvium is underlain by very stiff to hard sandy clay and silt with some rock fragments (residual soil) to ±33.5 feet, the maximum depth of exploration (BH-2). Kalama River Road, MP 9.16 Landslide June 6, 2013 Geotechnical Investigation Project 212-2-018 Cowlitz County, Washington 3. Cowlitz County, Department of Public Works

Based on BH-1, the residual soil is underlain by extremely weak (R0), moderately to highly weathered pyroclastic (Goble Volcanics). A more detailed description of soil and rock conditions encountered in the borings is summarized in appended logs (Appendix A). Ground Water The mud-rotary drilling methods used for the boring did not permit measurement of ground water levels during drilling. The piezometer was installed in BH-2, instrumented with a Level Troll 300 data logger to take measurements at 12-hour intervals. Wet areas observed on the slope and above the road were used as indicators of ground water near the ground surface. The ground water monitoring between September 15, 2012 and April 29, 2013, indicated the water level fluctuated from 4 to 6.8 feet above the elevation of the identified slide surface. No slide movement was observed during this monitoring period, so the water level needed to initiate movement is likely higher. LABORATORY TESTING The laboratory testing program included natural water content, percent fines and Atterberg limits tests to classify the soils and estimate their overall engineering properties. Water content testing was performed in general accordance with the Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass (ASTM D2216). Results of natural water contents are shown on the borehole log (Appendix A). Two percent fines tests and two Atterberg limits tests were performed in general accordance with the Standard Test Methods for Amount Materials in Soils Finer than No. 200 (75- m) Sieve (ASTM D1140) and Standard Test Methods for Liquid limit, Plastic Limit, and Plasticity Index of Soils (ASTM D4318). Results of percent fines tests indicated that the fines ranged from 72.9 to 83.7%. Results of Atterberg limits tests indicated that the liquid limit ranged from 54 to 71% and the plastic limit ranged from 35 to 39%. Based on Unified Soil Classification System (USCS), the samples were classified as high plasticity silt (MH). Results of percent fines and Atterberg limits tests are summarized in Table 1. A graph of the Atterberg limits (Figure 2B) is attached in Appendix B. Kalama River Road, MP 9.16 Landslide June 6, 2013 Geotechnical Investigation Project 212-2-018 Cowlitz County, Washington 4. Cowlitz County, Department of Public Works

Sample ID Table 1. Percent Fines and Atterberg Limits Test Results Depth (feet) Natural Water Content (%) Percent Fines (%) Liquid Limit (%) Plasticity Index (%) USCS Designation SS-2-3 15 to 16.5 40.2 83.7 54 19 MH SS-2-5 26 to 27 39.9 72.9 71 32 MH MITIGATION OPTIONS Common mitigation options for similar landslides include: a shear key buttress, road realignment, subsurface drains, and horizontal drains. Inclinometer measurements indicated the slide movement is relatively deep at 28 feet (Figure 3B, Appendix B). Therefore, a shear key buttress would require extensive excavation that appears impractical for this site. Therefore, we evaluated relocation of the road and drainage options. Road Realignment This option involves relocating the road to follow the private Weyerhaeuser Access Road and Greenwood Road, north of the present route. While this option avoids the active site, it does not eliminate the risk of future movement. Soil and topographic features observed along Greenwood Road are similar to the areas that have experienced slide movement in the Kalama River area. This option would require further site investigation and analysis, and may require right-of-way acquisition and road widening. Drainage Improvement This option involves a subsurface drain on the north side of the road and possibly horizontal drains drilled from near the mapped toe of the landslide. In our experience, the subsurface drain alone may not provide enough improvement in stability. Therefore, we anticipate horizontal drains will also be required. Option Selection Subsurface drains and relocating the road are potential options for repair and mitigation of this landslide. As discussed in the preliminary evaluation, drainage may not eliminate all future movement. However, all landslide mitigation involves risks and drainage options may be the most cost effective. Relocation of the road to a neighboring alignment was also considered, but all alignment options in this area include risk of future movement. For this site, we anticipated that drainage improvements will be the most cost effective mitigation method. Based on monitoring from April 10, 2009 to January 19, 2011, we observed movement occurred following periods of unusually Kalama River Road, MP 9.16 Landslide June 6, 2013 Geotechnical Investigation Project 212-2-018 Cowlitz County, Washington 5. Cowlitz County, Department of Public Works

wet weather during the winter months. Prolonged movement extending through the summer was not observed. Therefore, lowering the ground water within the slide mass is expected to improve the stability and reduce future road damage. We anticipate that a combination of horizontal drains and a subsurface drain can be designed to lower the ground water level and provide a reasonable improvement in slope stability. ANALYSIS AND DESIGN Slide 5.0 software was used to calculate the slope stability for the existing conditions and the projected drained condition. Surface mapping and the subsurface exploration were used to develop a cross-sectional model of the landslide. The slide surface friction was calculated by back-analyzing a soil strength of = 21 to provide a factor of safety of ±1.0 for the assumed ground water conditions at failure. This friction angle is consistent with the expected residual strength for the soil observed in the boring. The results of the back analysis and assumed geotechnical parameters are summarized in Table 2 and attached in Appendix C. Table 2. Summary of Geotechnical Parameters and Results of Analyses Analysis Conditions Factor of Safety Back-analysis with assumed low water condition at failure 0.99 Ground water lowered 6 feet at the ditch and 12 feet below the slope 1.21 Ground water lowered 8 feet at the ditch and 18 feet below the slope 1.30 Ground water lowered 10 feet at the ditch and 18 feet below the slope 1.31 We analyzed the potential effect of a subsurface drain on the north side of the road by lowering the ground water surface 6 to 10 feet below the uphill ditch. The influence of horizontal drains installed from near the toe of the landslide was modeled by lowering ground water level up to 18 feet below the slope. Based on the estimated reduction in ground water elevation provided by the subsurface drains and horizontal drains, we calculated up to ±30 percent improvement in slope stability over the existing condition. We anticipate that the drains could significantly reduce the frequency of future landslide movement. Some future movement is typically possible for drainage improvement options. However, since movement in this site is infrequent, drainage options are likely to provide acceptable results. Mitigation Design Horizontal drains could be installed from a drain gallery located at the base of the slide with access from the private drive south of the County road. The horizontal Kalama River Road, MP 9.16 Landslide June 6, 2013 Geotechnical Investigation Project 212-2-018 Cowlitz County, Washington 6. Cowlitz County, Department of Public Works

drains would outfall near ±El. 364 feet (Cowlitz County local datum). The drainage design should also include a subsurface drain installed above the road as discussed below. The horizontal drains involve drilling five, ±170 to 190-foot long drains extending upslope from a drain gallery located near the base of the slope, 70 feet north of the private drive as shown on Figure 2. The drain gallery should be constructed with 1(H):1(V) maximum side slopes. Table 3 lists the location, direction and vertical angle of the proposed horizontal drains. Note that elevations refer to the elevation provided by the Cowlitz County survey. These locations are for planning purposes and should be adjusted in the field during construction. A detail of the proposed drain outfall is provided on Figure 4. Drain Number Table 3. Horizontal Drain Locations Collar Elev. Length (feet) Azimuth (degrees) Vertical Angle (degrees) Drain Gallery (El. ± 356 ft) 1 1 364 170 332 15 2 364 180 339 16 3 364 190 346 16 4 364 190 353 16 5 364 180 360 16 Note: 1. Gallery elevations refer to a Cowlitz County survey. 2. Dimensions, elevations, azimuths, and vertical angles are approximate and subject to change by field engineer. The drainage improvements should also include a ±10-foot deep subsurface drain in the uphill roadside ditch of Kalama River Road. The subsurface drain should span the length of the slide as indicated in Figure 2 and outfall near El. 420. A detail of the subsurface drain is included in Figure 3. The existing culvert should be replaced with High Density Polyethylene (HDPE) pipe to withstand ground movement without breaking and reduce the chance of releasing water directly into the landslide cracks. The culvert should be angled to the west to avoid draining directly onto the landslide and drain gallery. RECOMMENDATIONS Drainage Recommendations 1. Construct a ±10-foot deep subsurface drain in the uphill roadside ditch of Kalama River Road as shown in Figure 3. 2. Replace the existing CMP and Concrete culvert with an HDPE pipe. Angle the pipe to outfall west of the slide, ±65 feet west of the existing outfall. Kalama River Road, MP 9.16 Landslide June 6, 2013 Geotechnical Investigation Project 212-2-018 Cowlitz County, Washington 7. Cowlitz County, Department of Public Works

Horizontal Drains 3. Prepare access to the horizontal drain gallery location shown on Figure 2. Construct temporary access roads with a separation or drainage geotextile and at least 8 inches of 4-inch minus angular rock. 4. Construct the excavation for the horizontal drain gallery at the location shown on Figure 2. Excavate for the drain gallery with side slopes of 1(H):1(V) or flatter. Slope the base of the drain gallery to drain. 5. Install the horizontal drains at the horizontal and vertical angles shown on Table 3 and near the locations in Figure 2. The final location, direction and angle of the horizontal drains should be adjusted by the engineer in the field. 6. Install the horizontal drains using equipment capable of drilling through soil and weak rock. Use the specification attached in Appendix D. A detail for the horizontal drain outfall is provided on Figure 4. CONSTRUCTION OBSERVATION We should be present during construction to observe the excavation of the drain gallery, installation of the horizontal drains, and assist with location of the horizontal drains. Any geotechnical engineering judgment required in the field should be provided by an FEI representative. VARIATION OF SUBSURFACE CONDITIONS, USE OF THIS REPORT AND WARRANTY The analysis, conclusions, and recommendations contained herein are based on surface observations, exploratory drilling, and instrumentation. The above recommendations assume that we will have the opportunity to be present during construction to confirm the location of the subsurface drain, horizontal drains, slide surface and soil conditions. No changes in the enclosed recommendations should be made without our approval. We will assume no responsibility or liability for any engineering judgment, inspection, or testing performed by others. This report was prepared for the exclusive use of Cowlitz County for the Kalama River Road Mile Post 9.16 Landslide. Information contained herein should not be used for other sites or for unanticipated construction without our written consent. This report is intended for planning and design purposes. Contractors using this information to estimate construction quantities or costs do so at their own risk. Our services do not include any survey or assessment of potential surface contamination or contamination of the soil or ground water by hazardous or toxic materials. We assume that those services, if needed, have been completed by others. Our work was done in accordance with generally accepted soil and foundation engineering practices. No other warranty, expressed or implied, is made. Kalama River Road, MP 9.16 Landslide June 6, 2013 Geotechnical Investigation Project 212-2-018 Cowlitz County, Washington 8. Cowlitz County, Department of Public Works

We hope this discussion meets your current needs and look forward to assisting you with the design of the selected alternative. Please do not hesitate to call with any questions. REFERENCES Phillips, W.M, 1987, Geologic Map of the Vancouver Quadrangle, Washington and Oregon, Washington Division of Geology and Earth Resources Open File Report 87-10. Fiksdal, J.A., 1973, Slope Stability of Longview-Kelso Urban Area, Cowlitz County, Washington Department of Natural Resources Open-File Report 73-2, Revised 1989. Wegmann, K.W., 2006, Digital Landslide Inventory for the Cowlitz County Urban Corridor, Washington: Washington Division of Geology and Earth Resources Report of Investigation 35, Version 1.0, 28 p. Kalama River Road, MP 9.16 Landslide June 6, 2013 Geotechnical Investigation Project 212-2-018 Cowlitz County, Washington 9. Cowlitz County, Department of Public Works

Appendix A Boring Logs Professional Geotechnical Services Foundation Engineering, Inc.

Depth Feet 1 2 3 4 5 6 Asphalt, (±18 inches). Soil and Rock Description and Comments Base Rock Aggregate, (±6 inches). Medium stiff sandy CLAY, trace gravel, (CL); brown, iron-stained, damp to moist, low plasticity, fine to coarse sand, fine gravel, subangular gravel, scattered organics, (fill). Log Elev. Depth 0.0 1.5 2.0 Samples SS-2-1 SPT, Moisture, % N-Value Recovery RQD., % 0 50 100 8 Installations/ Water Table 8-inch Sherwood monument set in concrete Bentonite chips 7 8 9 10 11 12 13 Medium stiff sandy CLAY, trace gravel, (CL); brown, iron-stained, damp, low to medium plasticity, fine to coarse sand, fine gravel, angular gravel, scattered organics, (colluvium). 10.0 SS-2-2 7 14 15 16 17 Medium stiff clayey SILT, some sand, trace gravel, (MH); grey-mottled brown, iron-stained, wet, high plasticity, fine to coarse sand, fine gravel, angular gravel, (colluvium). 15.0 SS-2-3 5 18 19 20 21 22 Soft CLAY, trace sand and gravel, (CL); dark brown, iron-stained, wet, low to medium plasticity, fine to medium sand, fine angular gravel, (colluvium). 20.0 SS-2-4 4 23 24 25 26 27 28 29 30 31 32 33 Brown, mottled red-grey organics at ±25.8 feet. Medium stiff clayey SILT, some sand, trace gravel, (MH); brown, iron-stained, wet, high plasticity, fine to coarse sand, fine gravel, angular gravel, (colluvium). Very stiff sandy CLAY, trace gravel, (CL); brown, blue-grey mottled, moist to wet, medium plasticity, fine to coarse sand, fine gravel, angular gravel, ±4 inches of clayey silt at ±28 feet, (residual soil). Hard SILT, (ML); light grey, iron-stained, damp to moist, low to medium plasticity, (residual soil). Becomes clayey SILT, trace sand, (MH); brown, at ±29.5 feet. Hard SILT, some sand, trace gravel, (ML); brown, iron-stained, damp to moist, low to medium plasticity, fine to coarse sand, fine gravel, angular gravel, weathered rock fragments, (residual soil). BOTTOM OF BORING 25.8 27.0 28.5 32.0 33.5 SS-2-5 SS-2-6 SS-2-7 SS-2-8 SS-2-9 28 50/4" 85/11" Project No.: 2122018 Boring Log: BH-2 Surface Elevation: (Approx.) Kalama River Road MP 9.16 Date of Boring: September 14, 2012 Foundation Engineering, Inc. Cowlitz County, WA Page 1 of 1

Appendix B Field Monitoring and Laboratory Testing Results Professional Geotechnical Services Foundation Engineering, Inc.

Kalama River Road MP 9.16 Date 9/1/12 10/27/12 12/22/12 2/16/13 4/13/13 6/8/13 20 22 Ground Water Depth (feet) 24 26 28 Slide Zone Level Troll 30

ATTERBERG LIMITS TEST PLASTICITY CHART 70 60 50 PLASTICITY INDEX (PI) 40 30 20 CH MH CL 10 CL-ML ML 0 0 10 20 30 40 50 60 70 80 90 100 LIQUID LIMIT (LL) SS-2-3 SS-2-5 Depth 15-16.5 26-27 Material Description USCS W% LL PL PI %Fines Medium stiff clayey SILT MH 40.2 54 35 19 83.7 Medium stiff clayey SILT MH 39.9 71 39 32 72.9 FOUNDATION ENGINEERING, INC. Professional Geotechnical Services

0 KALRIV BH-1, A-Axis 0 KALRIV BH-1, B-Axis 5 5 10 10 15 15 Depth in feet 20 25 Depth in feet 20 25 30 30 35 35 40 4/30/2009 11/25/2009 1/26/2010 8/4/2010 1/19/2011 45-1.00-0.50 0.00 0.50 1.00 Cumulative Displacement (in) from 3/3/2009 40 4/30/2009 11/25/2009 1/26/2010 8/4/2010 1/19/2011 45-1.00-0.50 0.00 0.50 1.00 Cumulative Displacement (in) from 3/3/2009

Appendix C Calculations Professional Geotechnical Services Foundation Engineering, Inc.

400 300 200 Safety Factor 0.000 0.250 0.500 0.750 1.000 1.250 1.500 1.750 2.000 2.250 2.500 2.750 3.000 3.250 3.500 3.750 4.000 4.250 4.500 4.750 5.000 5.250 5.500 5.750 6.000+ Colluvium/Fill 0.986 Document Name File Name: KalamaRd_MP9.16 Material Properties Colluvium/Fill Unit Weight: 115 lb/ft3 Cohesion: 0 psf Friction Angle: 32 degrees Water Surface: Water Table Custom Hu value: 1 Slide Surface Soil Unit Weight: 110 lb/ft3 Cohesion: 0 psf Friction Angle: 21 degrees Water Surface: Water Table Custom Hu value: 1 100 Slide Surface Soil W Residual Soil/Rock Unit Weight: 130 lb/ft3 Cohesion: 500 psf Friction Angle: 34 degrees Water Surface: Water Table Custom Hu value: 1 Residual Soil/Rock W 0-100 0 100 200 300 400 500

400 300 200 Safety Factor 0.000 0.250 0.500 0.750 1.000 1.250 1.500 1.750 2.000 2.250 2.500 2.750 3.000 3.250 3.500 3.750 4.000 4.250 4.500 4.750 5.000 5.250 5.500 5.750 6.000+ Colluvium/Fill 1.214 Document Name File Name: KalamaRd_MP9.16 Material Properties Colluvium/Fill Unit Weight: 115 lb/ft3 Cohesion: 0 psf Friction Angle: 32 degrees Water Surface: Water Table Custom Hu value: 1 Slide Surface Soil Unit Weight: 110 lb/ft3 Cohesion: 0 psf Friction Angle: 21 degrees Water Surface: Water Table Custom Hu value: 1 100 Slide Surface Soil W Residual Soil/Rock Unit Weight: 130 lb/ft3 Cohesion: 500 psf Friction Angle: 34 degrees Water Surface: Water Table Custom Hu value: 1 Residual Soil/Rock W 0-100 0 100 200 300 400 500

400 300 200 Safety Factor 0.000 0.250 0.500 0.750 1.000 1.250 1.500 1.750 2.000 2.250 2.500 2.750 3.000 3.250 3.500 3.750 4.000 4.250 4.500 4.750 5.000 5.250 5.500 5.750 6.000+ Colluvium/Fill 1.277 Document Name File Name: KalamaRd_MP9.16 Material Properties Colluvium/Fill Unit Weight: 115 lb/ft3 Cohesion: 0 psf Friction Angle: 32 degrees Water Surface: Water Table Custom Hu value: 1 Slide Surface Soil Unit Weight: 110 lb/ft3 Cohesion: 0 psf Friction Angle: 21 degrees Water Surface: Water Table Custom Hu value: 1 100 Slide Surface Soil W Residual Soil/Rock Unit Weight: 130 lb/ft3 Cohesion: 500 psf Friction Angle: 34 degrees Water Surface: Water Table Custom Hu value: 1 Residual Soil/Rock W 0-100 0 100 200 300 400 500

400 300 200 Safety Factor 0.000 0.250 0.500 0.750 1.000 1.250 1.500 1.750 2.000 2.250 2.500 2.750 3.000 3.250 3.500 3.750 4.000 4.250 4.500 4.750 5.000 5.250 5.500 5.750 6.000+ Colluvium/Fill 1.297 Document Name File Name: KalamaRd_MP9.16 Material Properties Colluvium/Fill Unit Weight: 115 lb/ft3 Cohesion: 0 psf Friction Angle: 32 degrees Water Surface: Water Table Custom Hu value: 1 Slide Surface Soil Unit Weight: 110 lb/ft3 Cohesion: 0 psf Friction Angle: 21 degrees Water Surface: Water Table Custom Hu value: 1 100 Slide Surface Soil W Residual Soil/Rock Unit Weight: 130 lb/ft3 Cohesion: 500 psf Friction Angle: 34 degrees Water Surface: Water Table Custom Hu value: 1 Residual Soil/Rock W 0-100 0 100 200 300 400 500

Appendix D Horizontal Drain Specifications Professional Geotechnical Services Foundation Engineering, Inc.

HORIZONTAL DRAIN SPECIFICATIONS HORIZONTAL DRAINS This w ork w ill consist of installing Horizontal Drains at the approximate location show n on the plans. The final location and orientation of the holes w ill be determined in the field by the engineer. The holes w ill be installed in clay, silt, and decomposed basalt w ith drilling conditions that vary from soil to soft rock. The subsurface conditions are summarized in a memorandum dated May 26, 2010. MATERIALS Horizontal Drain Pipe Horizontal drains shall consist of nominal 1 1/2-inch, Schedule 80 polyvinyl chloride (PVC) plastic pipe conforming to the requirements of ASTM Designation D 1785. At the option of the Contractor, the type, grade, and design stress designation of the pipe shall be either 1120, 1220, 2110, 2112, 2116 or 2120 as specified in said ASTM Designation. 1. Slotted pipe shall have 2 row s of slots. The row s shall be in the longitudinal direction of the pipe and the slots shall be cut in the circumferential direction of the pipe. The row s shall be centered on 2 of the third points (120 degrees apart) of the pipe circumference. Each row of slots shall conform to the follow ing configuration. Number of Slots per lineal foot (± 1) Width of Slot Minimum Opening per linear foot (square inches) (inch) 22 0.02 1.00 2. Slots shall be spaced uniformly along the pipe. The minimum opening w ill be measured on the inner surface of the pipe. 3. Fittings for the PVC plastic pipe shall be Schedule 80 Type II PVC solvent w eld type fittings conforming to the requirements in ASTM Designation D 2467. Machined male and female ends may be used in lieu of couplings. 4. The horizontal drain outfall shall be constructed as show n on the plans using steel pipe to protect the plastic drainpipe. Use steel pipe per 9-30.1(4)B and fittings per 9-30.2(4)B. Construction Requirements This w ork consists of furnishing and installing horizontal drains as show n on the plans or as directed by the Engineer and as specified in these specifications. 1. The drains shall be installed as show n on the plans. The locations and orientations of horizontal drains show n on the plans are approximate only and the final location and sequence of placing horizontal drains shall be as directed by the Engineer. 2. The horizontal holes shall be drilled w ith equipment capable of drilling 4-inch to 6-inch diameter holes up to ±320 feet in length to designated lines and grades through soil and rock formations. 3. Plastic pipe shall be installed by pushing it into the hole w ith slots on top or, at the Contractor' s option, shall be installed by inserting the pipe inside the drill rod w ith slots on top and then retracting the drill rod so that the drilled

hole is cased for the full depth. The end of the slotted segment of the plastic pipe shall be capped w ith a rounded or pointed extension. 4. Water used for drilling and w ater developed during drilling operations shall be disposed of by the Contractor in such a manner that no damage w ill result to the project or the environment. Turbid w ater may not enter into w aterw ays. Dispose of sediments or cuttings produced during drilling in a manner that no damage w ill result to the project or the environment. 5. Follow ing the completion of each drain, the Contractor shall determine the azimuth and inclination along the horizontal drains at 50-ft intervals using a single shot magnetic device or other means approved by the Engineer. The Contractor shall furnish all labor, materials, tools, equipment, and incidentals necessary for determining the azimuth and inclination. Measurement The pay quantity for horizontal drains w ill be measured by the linear foot for drilling holes w hich includes furnishing and installing either slotted or unslotted drain pipe, and all of the outlet fittings and steel pipe. The pay length w ill be from the collar tee to the end of the perforated plastic pipe. Payment Horizontal Drains, per linear foot.