Sunset Valley approved the $8.5 million city facility project to construct a public works building and a police facility at the Sunset Valley City Hall property. The pond was built as part of the project and makes up about $850,000 of total project cost.
According to Robert Scholz, a senior project manager with Halff Associates, the engineering firm that designed the pond, the feature is supposed to work as a water retention and reirrigation pond. As designed, the pond should not release water downstream and should be capable of catching more water than required by water quality standards.
However, according to a Jan. 21 City Council presentation by City Administrator Sylvia Carrillo-Trevino, the pond and an associated rain garden are not operating as designed. She said the pond’s clay liner was not correctly installed by Chasco Contractors, the business that worked on the project, and that she believes there is water leakage in other areas, preventing the pond to retain water.
“We are invested in getting this fixed,” Chasco Project Manager Tina Rutterford said. “We are invested in getting this done properly. We are going to fix it, but I don’t know how long [it will take]. It can be a needle in a haystack crack in the pond.”
During a test of the pond, the structure lost about one foot of water in a 30-hour period, when less than an inch of loss was expected.
“We don’t know where that water is going,” Carrillo-Trevino said, suggesting the runoff could be compromising the neighboring structures at City Hall.
Similarly, the pond seems to stabilize its water level at a shallower depth than was designed.
“We [believe] there is a certain level that it comes to that the water stays at, so we feel like under that level the clay liner is intact and working,” Rutterford said. “Somewhere above that there is an issue, and unfortunately with clay liners it is very hard to track that down.”
Additional concerns include water pumps that are broken and not operational and a large amount of algae growth in the pond. Carrillo-Trevino said she believes the algae could lead to additional pump issues in the future.
“If water levels are not reaching designed points, the system cannot operate as designed,” she said. “There are algae, which will impact pump maintenance.”
Scholz said the algae are likely present because the water pumps are not circulating water. He said he also believes the bottom of the pond is shallower than designed, which could also increase algae production.
Problems with the pond’s accompanying rain garden are due to a missing section of clay liner, which should be replaced.
Course of action
City staff proposed not releasing any additional money for the city facility project until and the pond is resolved. Although there were some disagreements between city staff and Chasco as to the best course of action, the city directed Chasco to develop a method for repair.
“We are not in a position to tell them how to fix it,” Carrillo-Trevino said. “They designed it. They contracted it. If we try to tell them how to fix it, we take on some of that liability.”
Rutterford said the plan of action is to first track down where the leak is above the level that the water is staying and repair it. She also said Chasco will install the needed clay liner in the rain garden.
City Attorney Doug Young said Jan. 21 that the city “is in its rights to retain money” for work that was not done or is not done correctly.
City Council moved part of the discussion into executive session before reconvening the Jan. 21 regular council meeting. No action about the pond was taken following executive session.