CLIENT: Inland Design PROJECT: 10 Malin Road REQUIREMENT: PROFESSIONAL ENGINEERING SERVICES: Geotech/SW LOCATION: 10 Malin Road, West Whiteland Township DATE: September 8, 2014 ATTENTION: Chuck Dobson, P.E. via Email Bo Erixxon, Project Manager via Email PURPOSE The purpose of this report is to present the Findings, Conclusions and Recommendations relative to the physical investigation performed at the above captioned project location. INVESTIGATION Jason Culp, P.E. and Nick Banta were present on site Friday September 5 th, 2014 to conduct a subsurface investigation at the above mentioned project location. The investigation included eight (8) double ring infiltrometer tests to be conducted within proposed infiltration areas. The exact design of the stormwater facilities was not currently known as site data was required to provide preliminary design. The findings and conclusions generated are to provide the initial broad range characteristics for design. A final more detailed investigation of the site may be required as the design proceeds further. In additional to information for the Stormwater related facilities IES was also requested to record pertinent construction costs aspects of the site such as shallow groundwater, soil suitability, rock depth etc. Testing was conducted according to the Pennsylvania Stormwater Best Management Guidelines Appendix C: Site Evaluation and Soil Testing Procedures. All double ring tests were presoaked for a minimum of one hour or two 30 minute intervals prior to recording measured infiltration readings. FINDINGS The Findings below use abbreviated nomenclature germane to soil morphology and other BMP terminology. 1
Test Pit Logs: TP no. 1 Tested at 65 0-8 Topsoil Root mat 8-30 Lt. Brn. To Red Sandy SILT 30-132 Decomposed Schist 80-90% Coarse Fragments, very friable coarse Fragments (Channers) can be broken with significant hand pressure to rock hammer strikes Near vertical strike dipping towards the upslope side Limiting Zone Encountered-Rock @ 11, lack of sufficient soil medium will require filtering TP no. 2 Tested at 58 0-10 Topsoil Root mat 10-30 Reddish Gravels and Channerrs w/ Sandy SILT 30-165 Reddish Channers (schist) fragments with soil filled bedding/fracture planes Soil fill is reddish Silty SAND; coarse Fragments (Channers) can be broken with significant hand pressure to rock hammer strikes Near vertical strike dipping towards the upslope side No GW or Limiting Zone Encountered, lack of sufficient soil medium will require filtering TP no. 3 Tested at 70 0-7 Topsoil Root mat 7-55 Reddish Brn Channery Mica SILT 55-168 Tan/White Mica v.f. SAND & SILT Channery Friable coarse fragments No GW or Limiting Zone Encountered TP no. 4 Tested @ 74 BGS 0-12 Topsoil Root mat 12-36 Lt. Brn Channery Sandy SILT 36-72 Reddish Brn Channery Mica SILT Friable coarse fragments 72-15 Tan/White Mica v.f. SAND & SILT Channery Friable coarse fragments No GW or Limiting Zone Encountered TP no. 5 Tested @ 79 BGS 0-8 Topsoil Root mat 8-89 Lt Brn Gravels/Channers & f. Sandy Mica SILT 89-111 Reddish Brn Channery Mica SILT Friable coarse fragments 111 - Tan/White Mica v.f. SAND & SILT 168 No GW or Limiting Zone Encountered 2
TP no. 6 Tested @ 78 BGS 0-3 Asphalt Subbase 3A modified 3-8 8-15 Tan Sandy SILT Previous fill 15-96 Reddish Brn-Grey-Var v.f. Sandy Mica SILT Saprilite, very Friable CF s 96-172 Grey Mica SILT, Saprolite Friable CF s No GW or Limiting Zone Encountered TP no. 7 Tested @ 78 BGS 0-3 Asphalt 3-8 Subbase 3A modified 8-30 Brn f. Sandy Mica SILT l/s Previous fill Gravels 30-168 Grey Mica SILT S Saprolite of parent formation 96-172 Grey Mica SILT, Saprolite Friable CF s No GW or Limiting Zone Encountered TP no. 8 Tested @ 84 BGS 0-3 Asphalt 3-8 Subbase 3A modified 8-65 Gravelly v.f. Sandy Mica SILT Friable CF s, Fill 65-194 Grey/Tan/Var. v.f. Sandy SILT v. micaceous very steeply Very friable CF s, to near vertical bedding decomposed schist No GW or Limiting Zone Encountered Infiltration Testing TP No. 1 4 4 4 4 4 4 final stabilized reading with 10 minute intervals 24.0 inches/hour Final Stabilized Reading @ 65 inches BGS TP No. 2 3 ½ 3 ½ 3 ½ 3 ½ 3 ½ 3 ½ 3 ½ final stabilized reading with 10 minute intervals 21.0 inches/hour Final Stabilized Reading @ 58 inches BGS TP No. 3 ⅝ ¼ ¼ ¼ ¼ final stabilized reading with 30 minute intervals 0.25 inches/hour Final Stabilized Reading @ 70 inches BGS TP No. 4 ½ ½ ½ 3/8 3/8 3/8 final stabilized reading with 30 minute intervals 0.75inches/hour Final Stabilized Reading @ 74 inches BGS TP No. 5 1 1 ⅝ ½ ½ ½ ½ final stabilized reading with 30 minute intervals 3
1.0 inches/hour Final Stabilized Reading @ 79 inches BGS TP No. 6 1 1 1 1 1 final stabilized reading with 30 minute intervals 2.0 inches/hour Final Stabilized Reading @ 78 inches BGS TP No. 7 ¼ ¼ ¼ ¼ ¼ final stabilized reading with 30 minute intervals 0.5inches/hour Final Stabilized Reading @ 78 inches BGS TP No. 8 2 1¼ 1¼ 1¼ 1¼ 1¼ final stabilized reading with 30 minute intervals 2.5inches/hour Final Stabilized Reading @ 84 inches BGS CONCLUSIONS 1. The Design Engineer is recommended to use the above information for sizing the Proposed Stormwater Management Facilities with a slight rate reduction for subsurface infiltration facilities to ensure the longevity of the systems given the presence of fine grain soils and cohesive soil content. 2. The saprolite to residium strata that all tests were conducted within is highly variable both vertically and laterally. The majority of test areas with well draining tests was due to the near vertical bedding planes of the decomposed parent material (schist). The rapidly draining areas of test pits 1 and 2 is composed of decomposed parent rock, in this case Micaceous Schist to Gneiss. The material is highly decomposed however is in a platy, vertical orientation which promotes infiltration through the macropores of the soil/rock medium. In this area a filter layer of concrete sand will be necessary to ensure the proper filtering of pollutants to ensure water quality requirements are met. 3. We strongly recommends that a qualified Soil Engineer or representative thereof be present during infiltration facility installation to ensure the stone facility-sand-soil interface is placed at an appropriate depth to maximize recharge. Facility bottom elevation often varies as overlying soils are not uniform thus requiring over excavation in localized areas of the facility to maximize infiltration potential. 4. The geotextile fabric is recommended to not be utilized at the bottom of any infiltration facility as the liner is serving too often as a hydraulically restrictive material and creating a bath tub effect, ergo only utilize the geotextile on the sides and top of the trench. 5. Test Pit no. 1 is the only area which exhibited somewhat shallow rock refusal. All other test pits were excavated down to the maximum reach of the excavator. Most of the material is fractured and decomposed and therefore rippable, especially in a larger excavation. 4
6. The soils encountered are fine grained soils that are very moisture sensitive. Areas that achieve compaction will be susceptible to breakdown with repeated construction traffic on top of those areas. Additionally, the coarse fragments throughout the site are easily fractured and broken down and therefore will have similar negative effect with repeated traffic. 7. The site topography and open rapidly draining strata encountered at the upslope portion of the site may result in areas downslope receiving intermittent seepage in localized areas. This should be considered for design of retaining walls and for mitigation in any construction activities. 8. Refer to the attached laboratory data for additional information regarding the findings above. 9. Test Pit locations were provided in the field by Inland Design. Please refer to the attached image of then plan provided to IES for test pit locations. 10. Please contact IES should questions/concerns relative to subsurface geology arise during planning or construction phases of this project as actual field conditions are expected to vary and this report does not speak to all possible issues that might arise. Very Truly Yours, Jason Culp, P.E. Project Manager Ingram Engineering Services, Inc. 484.947.5549 office 610.431.7015 fax jason@ingram-engineering.com Chadd W. Ingram, P.E. (DE, MD, NJ, PA), S.E.O. Principal & CEO Ingram Engineering Services, Inc. 484.947.5549 office 610.431.7015 fax chadd@ingram-engineering.com 5
Ingram Engineering Services, Inc. 6
7
8
9
10
11
12