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31B-214 65 Gothic engineering 2017-12-13 Examine Garage – Hagadorn Residence Page 2 ED&T File Number: HFD5204-20442 December 6, 2017 BACKGROUND INFORMATION The Hagadorn residence, shown in Figures 1 and 2, is a single-family, wood-framed residence located at 65 Gothic Street in Northampton, Massachusetts. For the purpose of this report, the residence faces west toward Gothic Street. The residence was constructed in, or around, 1900 and has been owned by Ms. Caroline Hagadorn since 2005. Ms. Hagadorn lives out-of-state and utilizes the residence as a rental home. A two-bay, wood-framed, detached garage, identified by the arrow in Figure 2 and shown in Figures 3 through 5, is located northeast of the residence. The garage was constructed in 2008. The foundation of the garage consists of cast-in-place concrete walls and the floor of the garage consists of a concrete slab-on-grade (floor slab). A neighboring commercial building at 88 King Street, identified by Arrow 1 in Figure 6, is located behind (east of) the residence and garage, identified by Arrow 2 and 3 in Figure 6. An asphalt-paved parking lot extends behind the building, and slopes downward toward the garage of the residence. According to Ms. Beth Graham (current tenant of the residence), during the summer of 2017, the parking lot was extended an estimated two feet toward the rear of the garage. Since that time, she has noticed increased precipitation runoff collecting along the rear of the garage. Between October 24, 2017 and October 25, 2017, a storm passed through the Northampton, Massachusetts area producing heavy rain. Ms. Graham returned to the residence on the evening of October 25, 2017 to find signs posted on the garage by representatives from the Town of Northampton, shown in Figure 7, declaring it unsafe due to an opening that formed underneath a portion of the garage foundation and floor. Between October 27, 2017 and October 31, 2017, representatives from the Town of Northampton conducted testing and evaluation of the garage and surrounding area. Ms. Hagadorn, Ms. Graham, and representatives from the Town of Northampton are concerned about the cause resulting in the opening beneath the garage. Examine Garage – Hagadorn Residence Page 3 ED&T File Number: HFD5204-20442 December 6, 2017 WORK OF INVESTIGATION Engineering Design and Testing Corp. (ED&T) was contacted in the matter on November 1, 2017. An examination of the residence was conducted on November 10, 2017. The scope of work by ED&T included a visual examination of portions of the garage and surrounding area. Ms. Graham was present during the examination and provided background information. Photographs were taken to document the examination. In this regard, Figures 1 through 15 have been made part of this report. As part of the investigation, ED&T contacted representatives from the Town of Northampton. In this regard, Mr. Louis Hasbrouck, Building Commissioner, and Mr. Greg Newman, Senior Engineer (DPW), provided additional information. ADDITIONAL INFORMATION FROM THE TOWN OF NORTHAMPTON The following information was provided to ED&T by Mr. Louis Hasbrouck and Mr. Greg Newman. A map of the area surrounding 65 Gothic Street was provided to ED&T by Mr. Hasbrouck and is included as the appendix of this report. Modifications have been made to the map, by ED&T, some of which are referenced in the following information. 1. The private sewer line of the residence at 70 Gothic Street (located across Gothic Street from the residence at 65 Gothic Street), identified by Arrow 1 in the appendix, passes beneath Gothic Street, and the property of 65 Gothic Street (including the garage at 65 Gothic Street), and discharges into a 48-inch sewer main located behind the garage of 65 Gothic Street (beneath the parking lot of 88 King Street), identified by Arrow 2 in the appendix. It appears that the private sewer line of 70 Gothic Street also passes beneath the southeast corner of the property of 71 Gothic Street (the adjoining property to the north of the Hagadorn residence). There is no sewer easement for the private sewer line of 70 Gothic Street. Examine Garage – Hagadorn Residence Page 4 ED&T File Number: HFD5204-20442 December 6, 2017 2. On October 27, 2017, representatives from the Town of Northampton conducted a dye test of the private sewer line of 70 Gothic Street and confirmed that it discharges into the 48-inch sewer main behind the garage of the Hagadorn residence. 3. On October 31, 2017, representatives from the Town of Northampton inserted a camera into the private sewer line of 70 Gothic Street and observed that the sewer line (made of clay pipe) was broken beneath the vicinity of the Hagadorn garage and that it appeared soil had been entering the sewer line for “some time”. The 48-inch sewer main was visually inspected by representatives from the Town of Northampton and no damage to the sewer main was observed. OBSERVATIONS The following observations were made during the ED&T examination on November 10, 2017: 1. The residence at 70 Gothic Street, identified by Arrow 1 in Figure 8, is located across the street from the Hagadorn residence. 2. An asphalt patch, identified by Arrow 2 in Figure 8 and Arrow 1 in Figure 9, is located along the driveways of the Hagadorn residence and 71 Gothic Street. 3. A cleanout, identified by Arrow 3 in Figure 8 and Arrow 2 in Figure 9, is located near the middle of the asphalt patch. The cleanout provides access to the private sewer line of 70 Gothic Street and is where representatives from the Town of Northampton inserted a camera into the private sewer line. The asphalt patch was installed by representatives from the Town of Northampton after digging was required to access the private sewer line of 70 Gothic Street. Examine Garage – Hagadorn Residence Page 5 ED&T File Number: HFD5204-20442 December 6, 2017 4. An opening, identified by the arrow in Figures 10 and 11 and shown in Figures 12 and 13, was observed along the exterior of the foundation, along the east (rear) side of the Hagadorn garage. 5. The opening extends beneath portions of the foundation walls and the concrete floor slab of the garage, so that a void exists beneath the floor slab. 6. The interior of the garage, represented in Figures 14 and 15, was absent of visible damage resulting from the opening. DISCUSSION Recall that a private clay sewer line runs from 70 Gothic Street, beneath the garage of the Hagadorn residence, and discharges to a 48-inch sewer main located behind the garage. Clay pipes are not a common material used in modern construction. As such, it is reasonable to assume that the private clay sewer line of 70 Gothic Street is decades old, if not original to the construction of the residence. Over a long period of time, measured in decades, clay pipes are known to deteriorate and break. Recall that inspection of the private clay sewer line by representatives of the Town of Northampton deemed that the clay sewer line was broken beneath the vicinity of the garage of the Hagadorn residence. Broken sewer lines allow water to escape the line and saturate the surrounding soil, which can then flow back into the sewer line and be carried away. Over time, the repetition of removing saturated soil surrounding a sewer line is known to create subsurface voids. When the surface layer of soil is unable to support itself over a subsurface void, the surface layer is known to displace downward into the void. This displacement of soil can happen by itself, or it may be prompted by loading of the soil, such as when the surface layer of soil is saturated by heavy rain, similar to that which occurred between October 24, 2017 and Examine Garage – Hagadorn Residence Page 6 ED&T File Number: HFD5204-20442 December 6, 2017 October 25, 2017 in the Northampton, Massachusetts area. Although heavy rain may have caused the opening along the exterior of the garage of the Hagadorn residence to become visible on October 25, 2017, displacement of the soil could not have occurred if a void beneath the floor slab of the garage did not already exist due to the broken private sewer line of 70 Gothic Street. Based upon the preceding, it is concluded that, the opening beneath the garage of the Hagadorn residence is the result of a broken private sewer line that services the residence of 70 Gothic Street. CONCLUSION The opening beneath the garage of the Hagadorn residence is the result of a broken private sewer line that services the residence of 70 Gothic Street. REPAIR RECOMMENDATIONS The garage of the Hagadorn residence was absent of visible damage resulting from the opening. However, it is recommended that the private sewer line of 70 Gothic Street be addressed, and the opening beneath the garage filled, in order to prevent the current opening from widening and future openings from forming. Although the design of a repair to the private sewer line of 70 Gothic Street is outside of the scope of work for ED&T, the following repair recommendations are provided: Given the expected age and condition of the private sewer line of 70 Gothic Street, as well as the location of existing damage to the sewer line, it is recommended that a new sewer line be installed to service 70 Gothic Street, rather than attempting to repair the existing line. If it is necessary for the new sewer line of 70 Gothic Street to connect to the 48-inch sewer Examine Garage – Hagadorn Residence Page 7 ED&T File Number: HFD5204-20442 December 6, 2017 main behind the garage of 65 Gothic Street, it is recommended that the sewer line be diverted around the garage. As an alternative, consideration should be given to diverting a new sewer line from 70 Gothic Street to another nearby sewer main, such as those located along Gothic Street and Trumbull Road, identified by Arrows 3 in the appendix. The existing private sewer line of 70 Gothic Street can be removed when a new line is installed, or abandoned in place, and, if necessary, filled with a flowable fill. The opening beneath the concrete floor slab of the Hagadorn garage can be filled with a flowable fill as well, either from the existing opening outside of the foundation, or through one, or more, small hole(s) drilled through the concrete floor slab from the interior of the garage. FIGURES Figure 1 Southwest (front) corner of Hagadorn residence Figure 2 Northwest (front) corner of Hagadorn residence; arrow identifies detached garage Figure 3 Northwest (front) corner of garage Figure 4 Southwest (front) corner of garage Figure 5 East (rear) elevation of residence and garage Figure 6 View from King Street (looking west) Arrow 1 Commercial building (88 King Street) Arrow 2 Hagadorn residence Arrow 3 Hagadorn garage Figure 7 Sign posted on Hagadorn garage Figure 8 Gothic Street (looking west) Arrow 1 70 Gothic Street Arrow 2 Asphalt patch Arrow 3 Cleanout Figure 9 Gothic Street (looking east) Arrow 1 Asphalt patch Arrow 2 Cleanout Figure 10 East (rear) elevation of garage; arrow identifies opening Figure 11 East (rear) elevation of garage; arrow identifies opening Figure 12 Close-up view of opening (exterior of foundation) Figure 13 Close-up view of opening extending inside of foundation and beneath floor slab Figure 14 Interior of garage Figure 15 Interior of garage APPENDIX 65 Gothic St Northampton akuether manholes drain_intake drain_outfall drain_pipe <all other values> lateral subdrain detention_basin culvert channel sewer_mains road_names road_edge rail_trail lots_condos_asr condo lots hydro_surface hydro_linear Stream Intermittent DEP Wetlands northampton November 15, 2017 akuether | Web AppBuilder for ArcGIS 1:626 0 0.01 0.020.005 mi 0 0.02 0.040.01 km