Contractor will take underground video to assess debris
(Nov. 23, 2018) After spending $100,000 last month to clean storm basins along Coastal Highway in conjunction with the State Highway Administration, excessive blockages have required an outside contractor to videoscope pipes in search of clogged sections.
Public Works Director Hal Adkins said the city is working with the state, which owns and maintains Coastal Highway, Philadelphia Avenue and Baltimore Avenue, plus the associated storm drain systems, to address recurring flooding from heavy rainstorms.
Adkins said state highway crews spent about three weeks using a jet vacuum truck to clean storm basins on Coastal Highway north of 123rd Street.
“They found a substantial amount of accumulated sand and dirt,” he said. “In some cases, three quarters of the height of the drain pipe was completely blocked.”
Adkins said the state purview ends at the sidewalk, with Ocean City overseeing the remaining system, which includes 2,700 catch basins and 335-outfall locations.
“Those systems are interconnected,” he said. “Catch basins are piped and eventually drain out into the bay.”
After several weeks of pumping out debris from the storm drain system, state Highway crews hit a snag, Adkins said.
“It is my understanding they put a jet in to try and clean out one of these [pipes] and it got hung up,” he said. “They … will bring in a camera rig …… on wheels you can send up in there.”
Adkins said CES, an environmental services provider based in Delmar, will begin the next phase of work within a few weeks.
Adkins consulted with City Engineer Terry McGean to identify priority locations, including Sinepuxent Avenue between 130th Street and 146th Street.
“We have identified certain areas that we would like CES to focus on initially, areas that have historically had flooding and we feel that our drainage system may be rather clogged in those areas,” he said.
Adkins said attention would also be paid to the area west of Philadelphia Avenue between Ninth and 15th Street, along with additional trouble spots and long sections of pipe.
“When the grade is rather flat, you lose velocity,” he said. “When you lose velocity, the sediment suspended in the rain water falls out and fills up the pipe.”
As part of the project, the state will uncover previously paved-over junction boxes connecting catch basins on the east side of Coastal Highway with corresponding basins along the southbound bus lane.
“For whatever reason, as they’ve paved the highway over the years, they paved completely overtop of the junction boxes and circular metal lids,” he said. “When they put the manhole lid back, they’re going to have to set it at roadway grade and … patch around it.”
Noting the cost for CES to send a jet-vacuum truck with a two-person crew is $150 per hour, Adkins said the $100,000 City Council allocated from the Maryland Stormwater and Critical Area Mitigation fund would need to be bolstered in the future.
“It was competitively bid by state highway,” he said. “We wanted to start with an initial allocation of $100,000 to identify the worst-case scenarios to see how quickly we are able to address this.”
Adkins said he hopes the work undertaken by CES would help with estimating costs for future work, which could be considered during the coming year’s budget discussions.
“This will give us enough data as to what level of sediment buildup there is, data as to what our production rates can be, and how quickly can we do a typical city block of 300 feet,” he said. “Then we can extrapolate … total cost.”
Adkins also said Environmental Engineer Gail Blazer has requested materials removed from storm drain systems be retained for further analysis.
“She wants to know what volume we accumulate,” he said.
The data may allow Blazer to analyze if the project could be married to other regulatory or grant opportunity issues, Adkins said.
“The capacity of the water that’s coming down from the sky is exceeding the ability for that pipe to carry it away because the pipe is clogged and not at full capacity,” he said.
“The minute we get that front-end worth of debris out of there, the velocity of the water that will make it into the catch basin and the pipe will be at a much higher velocity to help clean out the rest of it.”