DUBLIN — A group of residents concerned that a new sports complex attached to a Christian center and school could create too much noise for their neighborhood is suing the center and the city.

“We’re not against sports, or the church. Their education system has done well for the city,” said Shirley Lewandowski, who has lived nearby for decades. “We savor our 31 years of quietness.”

West Dublin Alliance, a neighborhood group, filed the suit earlier this year in Alameda County Superior Court against Valley Christian Center of Dublin and the city of Dublin itself. The lawsuit alleges that the city did not properly study the noise impacts from a proposed 600-seat athletic field to be used for sports such as football and track. The project would also include a concession stand, ticket booth and a plaza, amphitheater and other landscaping.

The group wants a new environmental impact report, which would more closely study noise, traffic and light impacts for the proposed project. But the city instead used a 2003 environmental impact report, and conducted only what is called a “mitigated negative declaration,” finding that the proposed project will not have significant impacts on the environment. The 2003 report was used when Valley Christian first proposed a planned development for its site.

Valley Christian, which includes a preschool through high school in the 7500 block of Inspiration Drive, shares a property line with some homes located just below a small hill. The proposed sports complex would include a football field and eight lanes of tracks and bleachers, and would front the Inspiration Drive side of the campus. The field would be separated by the road itself, then the hill, before the residential neighborhood begins. But residents of the roughly 150-member neighborhood group say the noise from having football games located so close to their homes would be detrimental.

On a typical night, the average noise level in the evenings in that area is 48 to 50 decibels, according to the city’s study conducted by Illingworth & Rodkin.

The city staff report from City Council’s February meeting said that noise analysis was done by conducting tests at a similar high school football game in San Jose. That game between two popular rivals had 1,600 people attending — 1,000 people more then the 600-seat complex would have in Dublin.

The test found that such an event would raise the noise level by one decibel, bringing the total to the Dublin area to 49 to 51, which is below the maximum of 60 decibels allowed in the city.

But Stuart Flashman, the attorney for West Dublin Alliance, said because of the wind in the hills, it’s a unique area that needs to be tested otherwise.

So the city asked the noise consultant to evaluate the resident’s topography and wind concerns. The noise consultant then “applied assumptions,” the city report said. With the worst-case scenario, the wind would increase the noise levels by 4 to 5 decibels, resulting in 50 to 52 decibels total. This is still below the maximum for the area.

“While residents would experience a noticeable increase in noise, this increase would not result in a significant impact under CEQA (California Environmental Quality Act) that would require mitigation,” according to the city’s report.

Valley Christian promised that it would limit the times the loudspeaker system would be used — not before 10 a.m. on any day and only until 8 p.m. Sunday through Thursday, and 10 p.m. on Friday and Saturday nights.

The Christian center also said it would not rent out the facility to outside parties for music or entertainment purposes. It also lowered the seating capacity of the facility from the original proposed 1,100-seat bleachers to 600 seats.

In 2003, the city approved “planned development” zoning for the site, which served as an outline for construction and modifications to the location. This is how the city already had the 2003 environmental impact report on file.

A Dublin representative said the city does not respond to comment on pending litigation. Attempts to reach Valley Christian representatives were not successful.