Attachment_6_-_BEPA_CCTV_Report_FINAL.pdf

NATIONAL PARK SERVICE

U.S. DEPARTMENT OF THE INTERIOR

NATIONAL CAPITAL REGION

FACILITIES, DESIGN AND CONSTRUCTION

WASHINGTON, D.C.

Rehabilitate Belmont-Paul Monument CCTV Inspection Analysis

National Mall and Memorial Parks

NAMA

Washington, D.C.

July 18, 2018

Prepared by:

Alpha Corporation Dulles, VA

Contract No. P14PC00248 Task Number 24

NPS PMIS No. 236219

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Facilities, Design and Construction

WASHINGTON, DC

Table of Contents Introduction

Storm Sewer System A

Inlet #5 (Uppermost Structure):

Inlet #4 & Pipe Segment from Inlet #5 to #4:

Pipe Segment: Inlet #4 to MH #3:

Stairwell Inlet

Storm Sewer System B

East Roof Drain Connections

APPENDIX A – STORM DRAIN CCTV REPORT BY PIPELINE INVESTIGATIONS, INC

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Rehabilitate Belmont‐Paul Monument – CCTV Inspection Analysis

Introduction A closed‐circuit television survey inspection (CCTV) of the storm drain system at Belmont‐Paul Woman’s

Equality National Monument located at 144 Constitution Ave, NE Washington, DC was performed on

April 10, 2018 by Pipeline Investigations, Inc. A representative from Alpha Corporation and National

Park Service were also present on‐site during the CCTV investigations. There are two storm systems located on the site which will be referred to as “System A” and “System B” as described in the following paragraphs. The purpose of the CCTV inspection for “System A” varied from “System B” to meet the specific needs of the project as described in the paragraphs below.

“System A” begins at the storm inlet in the brick walkway on the west side of the building and continues along the west side of the building to the property line to a connection to the public combined system in

Constitution Avenue, NE. In general, the purpose of the CCTV inspection for “System A” was to determine the existing storm sewer pipe and material conditions, verify structure depths, observe flow conditions, and identify direction of flow within segments of the storm sewer located within the property. Prior field investigations by Alpha Corporation on July 24th, 2017 identified several areas of concern which were included in the CCTV inspections. This report discusses these areas of concern in relation to CCTV findings and provides recommendations for further action and/or correction.

“System B” is located on the east side of the building and connects to the public combined system located in 2nd Street NE. The purpose of the inspection for System B was to evaluate roof drain connections on the east side of the building for connection with the public system and observe pipe materials and conditions at roof drain connections. This report discusses the CCTV findings and provides recommendations for further action and/or correction.

Storm Sewer System A

Inlet #5 (Uppermost Structure):

Alpha Preliminary Investigations/Concerns: A brick walkway is located along the west side of the building. Storm sewer inlet #5 is located in the brick walkway. Alpha preliminary storm sewer analysis assumed roof drains along the northern end of the brick walkway connected to

Inlet #5. For additional information on Alpha preliminary investigations/concerns on this and

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other items, reference the “Rehabilitate Belmont‐Paul Monument” Schematic Design Report prepared by Alpha Corporation dated January 30, 2018.

CCTV Findings: CCTV Inspections confirmed the existence of a pipe (PVC, good condition) extending northeast from Inlet #5 to the west building face and toward the northwest building corner. No water was observed in inlet #5 or the upstream pipe. However, CCTV inspections observed sediment near the upper end of the pipe. The full extents of the pipe connection were unable to be assessed due to obstruction (bend and sediment) in the pipe which prevented camera passage to the full pipe extents.

Conclusions and recommendations: This pipe is assumed to be connected to the roof drain at the northwest corner of the building. Recommend flushing of the roof drain to clear existing debris. CCTV inspections indicated the depth of inlet #5 is approximately 17‐inches which is in close proximity to Alpha survey.

Inlet #4 & Pipe Segment from Inlet #5 to #4:

Alpha Preliminary Investigations/Concerns: Alpha preliminary investigations observed approximately 6‐inches of ponded water in inlet #4. This inlet is located in the brick plaza on the west side of the building. Alpha preliminary storm sewer computations indicated the existing 4‐ inch PVC sewer pipe that connects the storm inlet in the brick walkway (Inlet #5) to the storm inlet in the covered brick plaza (Structure #4) is currently operating at near design capacity during the 15‐year design storm. The length of pipe between Inlet #5 and #4 is approximately 40 feet according Alpha survey.

CCTV Findings: Water was observed in inlet structure #4 submerging both the entry and discharge pipes below water. CCTV inspections also observed water in the pipe segment between inlets #5 and #4 beginning approximately 12 feet downstream of the upstream structure (inlet #5). The water level in the pipe increased to completely full as the CCTV inspection continued downstream (southwest) to structure #4. At approximately 15 feet downstream (southwest) from inlet #5, a tap entered the pipe which was determined to be a connection from the building roof drain. Debris was also encountered in the pipe approximately

15 feet downstream from inlet #5 which prevented survey of the downstream portion of the pipe. However, a CCTV inspection of the pipe was also performed in the opposite direction

(beginning at inlet #4 continuing upstream/northeast). This inspection revealed a completely submerged pipe with blockage at approximately the same location in the pipe system.

Conclusions: CCTV inspections confirmed drainage issues within this segment of the pipe system. The cause of the drainage issues at the time of CCTV inspection appears to be due to back‐up of water in structure #4. There is also a blockage of debris in the pipe segment between inlet #5 and #4. CCTV inspections also confirmed the pipe material (PVC, in good condition where visible). The depth to both the inlet and outlet pipe was measured at approximately 45‐

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inches which closely corresponds to Alpha previous survey data. CCTV inspections also confirmed the connection of a roof drain from the west building roofline to this pipe segment as anticipated by Alpha preliminary investigations.

Recommendations: Correction of deficiencies in downstream storm system causing the back‐up in Inlet #4 as discussed in the paragraph below. These corrections will allow proper discharge from Inlet #5 to the public system and prevent back‐up into the upstream pipe. Alpha recommends replacing the 4” PVC pipe segment and increasing the size to 6 inches to increase flow capacity and reduce clogging of the pipe by debris (Option 1 improvements as indicated in the “Rehabilitate Belmont‐Paul Monument” Schematic Design Report prepared by Alpha

Corporation dated January 30, 2018.)

Pipe Segment: Inlet #4 to MH #3:

Alpha Preliminary Investigations/Concerns: Alpha preliminary storm sewer analysis indicated that the segment of pipe extending south of the inlet in the brick plaza (Inlet #4) appears to be currently sloping in the reverse direction. The direction of pipe slope corresponding to this pipe is based on Alpha survey invert out of the brick plaza storm structure and record data invert information for the structure southwest. See the “Rehabilitate Belmont‐Paul Monument”

Schematic Design Report prepared by Alpha Corporation dated January 30, 2018 for additional information.

CCTV Findings: In addition to CCTV inspection of the pipe which extended northeast from this structure as discussed previously, CCTV inspection was also performed in the opposite direction beginning at Inlet #4 and continuing southwest. This CCTV inspection observed water in Inlet #4 above the invert elevations and an unknown device or blockage at the very beginning of the southwest pipe opening blocking virtually all water from the inlet to the pipe. The CCTV camera was able to push through the blockage. Once through the blockage, CCTV inspections had clear visibility in the pipe, but the inlet water did not discharge despite the camera pushing though whatever was stopping the inlet water from entering the pipe.

Due to low visibility in the murky water, CCTV inspections were unable to identify what the unknown blockage was. CCTV inspections also noted the water level in the pipe dropped to less than five percent and continued at approximately this level or slightly higher for remainder of the pipe segment. At approximately 16.3 feet southwest of Inlet #4, leaves were encountered inside the pipe and a potential slight sag in the pipe was noted. The pipe inspection continued a total of approximately 42 feet where a brick manhole structure was encountered. This MH was holding water up to the approximate top of outlet opening elevation (outlet opening submerged).

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The CCTV inspection was unable to proceed beyond the brick structure and to the public storm sewer located in Constitution Avenue as was identified within the scope, due to a lack of an invert in the manhole or bottom of pipe to support the camera.

Conclusions:

o CCTV inspections were unable to determine if the blockage identified at the southwest pipe opening was the cause of a reverse slope condition on the pipe or miscellaneous blockage.

o Alpha had surveyed this structure on August 8, 2017 and required the assistance of NPS personnel to drain water from the inlet to observe invert elevations at the bottom of the structure. At the time, Alpha survey did not note the presence of a backflow prevention device or obstruction but did observe the outgoing pipe appeared to have been reset to a lower invert than originally designed.

o The fact that the CCTV inspections noted that once the camera equipment pushed through the obstruction, the inlet water did not discharge indicates a reverse flow pipe condition may exist. The presence of water at the downstream portion of the pipe indicates pipe slope is less than ideal and a sag in the pipe was observed by the CCTV.

o Potential alterations to pipe system since 1976 record drawings:

Record drawings indicated the pipe extending southwest of Inlet #4 is vitrified clay pipe (6‐inch VCP). CCTV inspections reveal the pipe material is Poly‐Vinyl

Chloride (PVC).

Record drawings indicate Inlet #4 connects to a manhole (MH #3) located at the southwest building corner approximately 32 feet downstream (southwest) of

Inlet #4. This structure and the structure further south are assumed to be buried and could not be located or accessed during Alpha field investigations or CCTV inspections without earth disturbance. CCTV inspection traveled approximately

42 feet south of Inlet #4 before a structure was encountered, which is approximately 10 feet greater than the length indicated in record drawings.

Recommendations:

o Alpha recommends replacement of existing Structure #4 and the pipe from Structure #4 to the southeast structure (existing Structure #3). We recommend increasing the pipe diameter between these structures to 8 inches to increase capacity and reduce the ability of obstructions and clogging. We recommend the slope of the pipe be set to provide positive drainage from Structure #4 to the southeast (existing Structure #3). The invert into existing Structure #3 should be set an elevation equal to or slightly higher than the invert out of existing Structure #3.

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o We recommend that work include discovering existing buried downstream structures and resetting of manhole covers to match existing grade to allow for access and maintenance of the storm drain pipe system.

o Once each manhole is investigated and uncovered, we recommend the CCTV inspection continue as originally planned to identify the condition of the storm drain pipe and flow conditions in the system to the outfall in Constitution Avenue. The CCTV effort would include a report of findings and provide recommendations to the COR based on its findings.

Stairwell Inlet

Alpha Preliminary Investigations/Concerns: An existing roof drain is present on the west side of the building which discharges at the bottom of a stairwell located at the west side of the building, south of the covered brick plaza. An inlet is located at the bottom of the stairwell to intercept runoff from the roof drain. During Alpha’s July 24th, 2017 site visit, NPS representatives indicated that this inlet previously experienced drainage issues (back‐up and clogging). At the time of the site visit, a temporary wire mesh had been placed at the bottom of the stairwell floor (over the drain opening) to prevent debris from entering the drain and causing blockage issues.

CCTV Findings: The pipe extending from the inlet opening was 3‐inches in diameter and was completely submerged with water beginning approximately 8‐inches below the top of pipe opening. The pipe appeared to extend vertically approximate 1 and a half feet below the top of pipe opening before a bend was encountered. The CCTV camera was unable to maneuver around the bend; thus, the CCTV inspection was terminated at the bend. Approximately 6‐ inches from the top of pipe, a PVC pipe entered the side of the pipe.

Conclusions & Recommendations: Standing water indicates potential pipe clogging or poor drainage conditions at the discharge location. As indicated in the January 30, 2018 Schematic

Design Report, we recommend connecting the existing roof drain currently discharging to the bottom of the existing stairwell to the underground storm sewer system located on the west side of the building. We recommend providing a new inlet cover for existing drain opening at bottom of existing stairwell that is currently screened by temporary wire mesh on the stairwell floor. The new inlet cover should be designed to accommodate the anticipated stormwater runoff from the stairwell and provide inlet protection from debris.

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Storm Sewer System B

East Roof Drain Connections

Alpha Preliminary Investigations/Concerns: On the east side of the building, there are four existing roof drains. Alpha field investigations indicated three of these four roof drains may not be currently connected to the underground sewer system. The purpose of CCTV inspections for

“System B” was to evaluate roof drain connections on the east side of the building for connection with the public system and observe pipe materials and conditions at roof drain connections.

CCTV Findings: CCTV Inspections numbered roof drains in decreasing sequential order along the east building face starting with roof drain 3 at the southeast building corner. CCTV inspections were as follows:

o Roof Drain East 3: Pipe is exposed 24‐inches above grade. After removing the roof drain bracket, several deceased birds and nests were found in the pipe. The birds and approximately 12 inches of compacted debris were removed; however, debris continued to fill the pipe.

o Roof Drain East 2: The roof drain connects to a corrugated HDPE drain pipe which extends several feet before terminating at grade in the landscape area. The HDPE corrugated pipe segment was full of debris.

o Roof Drain East 1: The roof drain does not connect to any pipe (discharge to splash block).

Conclusions & Recommendations:

o Roof Drain East 3: Recommend cleaning of the line to remove debris and returning the roof drain to working condition.

o Roof Drain East 2: Recommend replacement of HDPE pipe segment with perforated PVC pipe to prevent stormwater from pooling near the building structure.

o Roof Drain East 1: Recommend installation of perforated PVC pipe segment onto end of roof drain to direct runoff away from the building/stairway.

For additional Civil/Site related recommendations not associated with CCTV inspections, see the

“Rehabilitate Belmont‐Paul Monument” Schematic Design Report prepared by Alpha Corporation dated

January 30, 2018.

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APPENDIX A – STORM DRAIN CCTV REPORT BY PIPELINE INVESTIGATIONS, INC