Enlarging a nearby storm retention basin may allow building of an elementary school needed in southwest Manteca.

School officials are also exploring options with the South San Joaquin Irrigation District that may exist to use the water district’s facilities to dispose on storm run-off.

Manteca Unified is moving forward with construction design drawings for the school that will be located on 21 acres northwest of Woodward and McKinley avenues.

But the project can’t break ground until the district can demonstrate to the state there is adequate drainage.

Much of the water table in southwest Manteca is historically five feet while at certain times of the year it can drop down to 15 feet.

The situation is complicated by the fact the overall southwest Manteca area does not have an outlet to the river for storm water discharge.

The rest of the city is drained via the SSJID’s French Camp Outlet that runs along the train tracks that double as the border between the cities of Lathrop and Manteca.

There is a long-term project identified to drain southwest Manteca to the river by skirting the northern portion of Oakwood Lake Shores but it is expensive and far from being fully funded.

The hydrology is a safety issue for a school given water can back up if it can’t be drained from the campus.

Standalone solutions such as an on-campus retention basin or construction an underground catch basin would render an elementary school being built on the site impractical.

The first solution would create severe issues with trying to place needed facilities on the site given the state would only allow a shallow storm basin capturing a maximum of a foot or less of water due to the presence of children.

Most Manteca basins doubling as green open space in city parks can handle a maximum of four to five feet of water.

The other solution would make the elementary school cost prohibitive as it would require burying massive sections of over-sized culvert pipes.

Although some residents have criticized the city for not requiring the sizing of basins that were put in place in nearby parks when new subdivisions were built to accommodate the school site, it is the first time an elementary school is being built in an area with such a shallow water table.

The district would like to have additional classroom space in southwest Manteca area by 2028.

MUSD is also advancing construction plans for a second new elementary campus on Tinnin Road.

That site, however, is not yet annexed to the city. And unless it is, the district would have to come up with funding or costly infrastructure such as a water well, storm drainage, and a large septic system.

There is also a third option for getting classroom space in place in southwest Manteca.

That is the addition of an annex school on the Nile Garden campus.

Growth projections show housing development in the area justifies the construction of two free-standing elementary schools and eventually the Nile Garden annex.

The district has classroom space elsewhere to accommodate a number of additional students expected as more homes are built in southwest Manteca.

MUSD wants to avoid a situation where a large number of students from southwest area to be bused to campuses elsewhere — likely north of the 120 Bypass — because specific grade levels can’t be accommodated at their neighborhood school.

MCR Engineering is actively researching the capacity of basins within southwest Manteca to ensure school construction plans along with regional storm water management strategies.

To contact Dennis Wyatt, email dwyatt@mantecabulletin.com