LEWISTON — The happy faces of the Salvadoran children as they explored their new schools and bathrooms with running water, which the 136th Engineer Company helped build, was reward enough for the Maine unit’s commander.

“It was pretty amazing to see the children when they took over the schools,” Capt. Steven Morin, who led two groups of 136th soldiers to Sonsonate, El Salvador, this summer to build three schools and four bathrooms, said Friday as he prepared for a Guard weekend. “They were so excited.”

The 136th was part of Joint Task Force Jaguar, a 10-week humanitarian and training project that included solders and airmen from across the country and was commanded by Lt. Col. Raymond Valas of the New Hampshire National Guard.

The schools built by the international task force replaced unstable concrete structures with straw roofs that had been in use for years, Morin said, adding the children “were more interested in the bathrooms and the running water.”

The Maine unit worked with U.S. soldiers and airmen, coalition partners and Colombian engineers to complete the mission, he said.

“There was one area that didn’t have a school at all,” Morin said, referring to Las Marias, El Salvador. “So this building we built them, the biggest school that we built, housed a lot of schoolchildren. And it was just adjacent to their soccer field. They were so grateful.”

Morin left Maine in May with 70 citizen soldiers from his unit for a two-week deployment as part of the international training exercise called Beyond the Horizon-El Salvador 2013, and returned to the South American country in mid-June with a second group of 69 Maine Army National Guard soldiers.

The 136th Engineer Company is made up of carpenters, masons, electricians and plumbers who put their skills to work to better the lives of those living in the rural, underprivileged country, the Maine commander said.

The unit also has done work around Maine, including repairs at two camps done over the Guard weekend, according to Peter Rogers, spokesman for the Maine Department of Defense, Veterans and Emergency Management.

The annual Beyond the Horizon exercise and training offers U.S. soldiers and airmen an opportunity to train alongside international partners while doing humanitarian work and learning about a different culture.

“I had a mix of veterans and some brand-new soldiers,” Morin said of the Maine soldiers who deployed to El Salvador. “Some of the brand-new troops had never left the state.”

He added later that one 15-year veteran in the unit “said it was the best annual training he’s ever had.”

Soldiers had to deal a language barrier and weather that is much different than Vacationland.

“By 9 a.m in the morning it was 100 degrees and the humidity is really high and dehydration was an issue,” Morin said. “There were a lot of things that we did in the mission that we normally don’t have to deal with [in Maine]. It was very good, from a training aspect.”

To overcome the language barrier, bilingual task force members from other states were tapped as interpreters.

“I learned Spanish as we went along,” Morin said. “Not a lot of people in our area know Spanish but fortunately our medical people were from southern California and were bilingual.”

In addition to language, the Maine engineers also had to consider local resources when doing the construction projects.

“We put in an electric pump [then realized that] if the electric pump goes down, they won’t have any water,” Morin said. “They don’t have anybody to fix it.”

A solution came from a village elder who suggested installing a hand pump that can be put to use if the electric pump goes down.

“It was an ingenious little idea and we made it happen for them,” Morin said, adding that he was very pleased when he got a thumbs-up from the village elder.

“It was a fantastic mission, it really was,” the Maine commander said.