Grading & Base Preparation for Paving in Escondido

North County soils vary block to block

Much of inland North County formed from granitic rock that weathers into decomposed granite (DG), sandy soil that drains well but erodes when water runs across it. The Vista soil series, named for the area, is a well-drained coarse sandy loam formed this way.

Other areas sit on darker rock such as the San Marcos gabbro, which weathers into reddish, clay-rich soils. In the Las Posas series, for example, the subsoil averages 35 to 45 percent clay. Clay-rich soils can swell when wet and shrink as they dry, and pavement over them needs more base and good drainage.

Valley floors and drainages often have alluvium, layers of sand, silt and clay deposited by water, which can be softer and wetter.

What good base prep includes

• Excavating to firm soil and removing organic material, roots and soft spots.
• Compacting the subgrade before any rock goes down. Local public-works standards commonly call for 95 percent relative compaction under pavement.
• Geotextile fabric over clay-rich or soft subgrade to keep base rock from mixing into it.
• Crushed aggregate base (Class II base is common in California), placed and compacted in layers.
• Finish grades that move water off and away from the pavement, plus drains where needed.

Hillside and long rural driveways

Steep drives in areas like Valley Center, Hidden Meadows and the hills around Escondido add their own challenges: erosion at the edges, water running down the driveway itself, and heavy trucks on grades. These usually need careful grading, edge support and planned drainage.