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Home My WebLink AboutField Infiltration Test Report - - 364 JOHNSON STREET FIELD INFILTRATION TEST REPORT PROJECT INFORMATION Project: 364 Johnson Street, Single Family Home Addition Location: 364 Johnson Street,North Andover, Massachusetts Applicants: Gregory and Melissa Buitkus Engineer: John J. McDonnell, MSCE, PE, PLS Test Date: June 8, 2025 INFILTRATION TEST LOCATION Location: TH-1 as Depicted on Project Plans Test Hole Ground Surface Elevation: 255.8 ft TESTING METHODOLOGY The testing performed evaluated the rate of infiltration based on a"falling head" of water starting at a depth of 20 inches which was allowed to flow by gravity into the sidewall and bottom area of the virgin soil within the location of the proposed infiltration basin. The testing was performed within a four foot deep hole, excavated by hand at a width of 36 inches, which was adjacent to the 72-inch- deep observation hole excavated to evaluate the soil profile. After the infiltration test hole was excavated a foot of crushed stone was placed at the bottom and 8 inches of crushed stone was placed around the perimeter of a 20 Inch Diameter PVC Cylinder, the bottom of which was set at a depth of 36 inches below the ground surface. Prior to testing, a 60-gallon presoak was conducted. The infiltration rate recorded was based on timed measurements for the water table to drop to specific depths. After pre-soak the subsequent six falling head tests were conducted over an approximate one hour-period. During this time period the infiltration testing process reveals that there is a significantly higher rate of infiltration with greater hydraulic gradient ("head pressure"), when the system has 20 inches of head pressure. These results are consistent with Darcy's Law, regarding the gravitational flow of water through a porous media. Based on this testing the 20 inches of head pressure applied during the initial stages, results in the creation of a hydraulic gradient within the soil column, thus exerting head pressure within the testing components. Based on my testing, when the infiltration system is at or close to capacity, wherein it will have approximately 20 inches of head pressure, the infiltration rate will be greater than 36 inches per hour. I also determined through my testing that, within the proposed components of the infiltration system, when the water is not that deep,infiltration occurs at a slower rate. However, this will not have an impact on the performance of the system because there will be sufficient storage capacity within the system for this water. Further, as this water is allowed to accumulate and increase in depth, the head pressure will also increase, thereby increasing the infiltration rate. In order to accommodate this difference between the lower and higher head pressure, we have applied an average infiltration rate of 24.3 inches per hour, which is only based on the last three tests. Otherwise the infiltration rate per hour would be significantly higher. 1 Test Setup: 1. Excavation: o Observation Hole Excavated by Hand- Dimensions: 4' Diameter x 6' Depth o Deep hole excavation by hand to a depth of 71 inches, where groundwater was encountered 14��u(r � 1 r. 1NVI r✓,'i y I n �li o!/f r ��' r/c lit �1 wtl/r�l r �rllr�� Yo, 1 i h�W � � r /�i �r ym!f'r✓I�'41��i(��ry' � "I�N�j%��n��,,,Dh��r7i�pl �i��ir �rar IIW � �,�� i,;I �//f� �i/ "Y� o✓� r' � r U, r'i a/� III,,°,;✓ ;�� r/ /%//%�I///��:, r, ,� v I ffl y/�i/J�ry I i� r 2. Soil Profile : o Ground Surface = 0" 0 0" - 10": Horizon A - Topsoil 0 10" - 23": Horizon Bw, Fine Sandy Loam (FSL), 10YR 6/8 (brownish yellow) 0 23" - 74": Horizon C, Sandy Loam (SL), 2.5Y 5/6 (light olive brown) o Mottles Encountered at 48 inches o Water weeping at 71 inches in depth (Elevation 249.9 feet) o Soil texture: Predominantly sandy loam throughout profile 3. Test Hole: o The Infiltration Test Hole was located immediately adjacent to the Deep Observation Hole which is depicted as TH-1 on the Project Plans. 4. Testing Apparatus: o Container: Perforated Plastic Cylinder, 33-gallon capacity o Dimensions: 20 in (diameter) x 36 in (height) 2 o Hole Pattern: Holes drilled throughout cylinder o Hole Size: 1/2"in diameter o Hole Spacing: 3 in centers 5. Installation: o Cylinder placed in a hole excavated to a depth of 48 inches o Surrounded with 8 inches of crushed stone o Stone Type: Pea Gravel o Stone Size: 1/2"-3/4" o Stone Depth Surrounding the PVC Cylinder: 8 inches on sides TEST PROCEDURES Water Application/Initial Fill: o Presoak: 60 Gallons o Fill Height for Testing within Cylinder: 20 inches o Water Volume Added: —60 gallons o Presoak Fill Time: 15 minutes o Water Source: Hose r �y a f �f I� gl N�- Jf�/ ou 1 1 �r✓� �,' llU�Wtl r,// � r I,f I r: , r r. V /„� iwr y r ,:: ,yN � ��IIIII II '!'vt�lla"6 Wi rfj✓ �Y J)� f+ 1 1 f o f J Y � iml 1N r f III u 4 r6f r J TIMING AND MEASUREMENTS: Test Start Time: 2:45 Test End Time: 3:45 3 Total Test Duration: 1 Hour TEST MEASUREMENTS TAKEN FIRST TEST Fill the cylinder to a 20-inch depth Allow water to drop 1 inch, from the depth of 20 inches to 19 inches Time for this 1-inch Drop = 52 seconds Infiltration Rate: 69 inches per hour SECOND TEST Fill the cylinder to a depth of 20 inches After water was allowed to drop 4 inches measure the time for the water to drop from a depth of 16 inches to 12 inches Time for this 4 -inch Drop = 5 Min 10 Seconds Infiltration Rate: 46 inches per hour THIRD TEST Fill the cylinder to a depth of 20 inches Allow water to drop 1 inch from a depth of 19 inches to 18 inches Time for this 1-inch Drop = 1 min 7 seconds Infiltration Rate: 51 inches per hour FOURTH TEST Fill the cylinder to a depth of 20 inches Allow water to drop 6 inches from a depth of 19 inches to 13 inches Time for this 6-inch Drop = 8 Min 0 Seconds Infiltration Rate: 45 inches per hour FIFTH TEST Fill the cylinder to a depth of 20 inches Allow water to drop 10 inches to a depth of 10 inches then measure the time for a 1-inche drop from 10 inches to 9 inches Time for this 1-inch Drop =4 Min 0 Seconds Infiltration Rate: 15 inches per hour 4 SIXTH TEST Fill the cytinder to a,depth f 20 inches Allow water to drop fr hedepth of 12 inches, to 8 inches Time for th.is -I ch,, Dr - 18 Min. - 30 Seconds Infiltration Rate 13 inches Per hour INFILTRATIONRATEAS MEASURED INFIELD Average of the Last Three Measured Infiltration e 5 + 11.3=73/3= ',24.,33�l�nches/h,our Infiltration Rate: 243 inches/hour CALCULATED LTR ION USED FOR SYSTEM Apply the Safety Factor of 2.0 to Dete�rmine, the Design Infiltration, '"'ate: Design Rate= I. ' 1n es/hoer PROFESSIONAL CERTIFICATION l certify that this infiltration test was conducted .n accordance with accepted n _.neeri practices and,that the results presented herein,are accurate the best of my knowledge. TitleIoo 364 Johnson St., Field I ,I rati"on Test Report �"" a ��d y: John J. McDonnell SCSI, E� S, � CIVIL DNO-4,1157 ate: 5