Gravel, Sand, Fill and Rock Delivery in Miami, FL

Rain Totals That Drive Every Decision

The NOAA normals station at Miami Intl AP, FL, about 1 mile from the ZIP, averages 67.4 inches of precipitation a year. That is a lot of water to move off a driveway, a patio or a yard, and much of it can arrive in short tropical downpours that fill low spots within minutes.^[1]

Winter cold is a non-issue for stone here. The airport station averages 0.0 inches of snow and counts 0 days a year with a low of 32 F or colder, so frost heave never lifts a paver or loosens a gravel base.^[1]

Without frost to plan around, the whole design of a Miami project turns on drainage. Every layer should either shed water quickly or let it pass straight through, and the finished grade should send it somewhere it can soak in or flow away.^[1]

Hurricane season can bring days of rain in a row, and that is when the wet corners of a poorly drained yard show up. Low corners that stay wet for a day after a summer shower are the places to raise, regrade or drain before the next big storm.^[1]

Fine Sand Over Limestone

At the ZIP's center point, the USDA soil survey maps Urban land, 0 to 2 percent slopes, with urban land, paved or built over, covering 85 percent of the unit. The main named series is Naranja, at 3 percent of the map unit. Its top mineral layer is fine sand.^[2]

The Naranja soil is rated poorly drained, and its hydrologic group is A/D: it acts like group D while the water table is high and like group A where it has been drained. The sand itself lets water in fast, but when the ground is already full, rain has nowhere to go.^[2]

The survey records lithic bedrock at about 58 inches below the surface. The mapped geologic unit at the center point is the Miami Limestone, a Pleistocene formation of limestone and sandstone.^[2],[3]

Shrink-swell in the top 100 cm is low, at 0.2 percent. Sand barely changes volume as it wets and dries, so slabs and pavers set on it stay level as long as the sand is not washed out from under them.^[2]

The USGS puts the ground at the ZIP's center point just 10 feet above sea level.^[4]

A Parking Pad on Wet, Flat Sand

On ground with only 0 to 2 percent slopes, you have to build the grade in. Clear the area, add compacted Fill Sand or Fill Dirt to lift the pad a few inches above the surrounding yard, and shape it so water runs off one side toward a swale or the street.^[2]

Fine sand shifts under load when it is wet. Roll out woven fabric over the compacted subgrade, then spread a layer of Crushed Concrete or Road Base and compact it in lifts. The fabric keeps the stone from sinking into the sand, and the compacted base spreads the weight of a car.^[2]

For the surface, 3/4" Crushed Stone or #57 Crushed Stone stays open and drains, which suits a yard where rain arrives in sheets of runoff. Asphalt Millings make a darker, firmer finish that softens and binds in the heat.^[1]

Railroad Ballast and Riprap are much larger stone. Riprap armors the edge of a canal bank or a drainage swale where moving water would otherwise strip the sand away, and it is too large for a drive surface.^[2]

When the Water Table Comes Up

A group A/D soil changes with the season. When the water table is low, rain sinks into the sand almost as fast as it falls. When the table rises after weeks of storms, the same yard can hold standing water for days, because the ground below is already saturated.^[2]

A French drain or soakage trench helps only if it has a lower place to send water. On a flat lot, connect it to a swale, a dry well that reaches well-drained sand, or the street drainage, rather than running it into the middle of the yard.^[2]

Drain Rock is the stone for that work, since it has no fines to clog the spaces. #57 Crushed Stone does the same job and locks a little better under a walking surface. Wrap either one in fabric so the fine sand around it cannot wash in and fill the voids.^[2]

Under a downspout, a splash pad of River Rock slows roof water and spreads it out before it digs a hole in the sand. Along the drip line of a roof without gutters, a strip of River Rock or #57 Crushed Stone stops the rain from splashing sand onto the walls.^[1]

Pavers, Pool Decks and Patios

Pavers are a common choice on sandy ground because they flex instead of cracking. Set them on a compacted base of Road Base or Crushed Concrete, then a thin bed of Concrete Sand, and sweep sand into the joints. On a low lot, give the patio a slope away from the house and toward a lawn or swale.^[2]

Around a pool, Pea Gravel and River Rock make a cool, open border that drains splash water quickly. Keep them behind an edge so they do not get kicked onto the deck or into the water.^[1]

Mason Sand fills the joints of smaller pavers and works for mortar. Playground Sand is washed and screened for a play area, and it drains fast enough to dry out after a storm.^[2]

Stone Dust Screenings pack between flagstones into a firm joint that still lets some water through. Walkway Gravel makes a casual path to a side gate or a garden shed and drains as fast as the rain falls.^[2]

Homes, Gardens and the State Base Spec

The Census tallies 820 housing units within ZIP 33122. Detached single-family houses make up 7 percent of them, compared with 22 percent across Miami.^[5]

The median home in ZIP 33122 was built in 2014, while the median across Miami's 223,826 housing units is 1979. Owners occupy 4 percent of the occupied homes in the ZIP.^[5]

For planting beds on fine sand, mix Garden Soil or Compost into the top layer so it holds water and nutrients between storms. Topsoil levels a lawn area or fills a low spot before sod goes down. Black Shredded Mulch, Brown Shredded Mulch and Red Mulch keep the sand from drying out in the sun and cut down on weeds, and Wood Chips hold up on paths.^[2]

The Florida Department of Transportation names Graded Aggregate Base in Section 204 of its Standard Specifications for Road and Bridge Construction. A highway base is a graded blend of stone sizes compacted into a dense, stable layer, and that is the same goal for a residential pad on soft sand.^[6]