Gravel, Stone, Sand and Soil Delivery in Philadelphia, PA

A Mixed Gravel Deposit Below the Pavement

The USDA soil survey maps Urban land at the ZIP's center point, and 90 percent of the map unit counts as paved or built over. In a center-city setting, that covered ground is a patchwork of old foundations, utility trenches and fill.^[1]

Under the fill, the state geologic map shows Trenton Gravel at the center point, a Pleistocene deposit of sand, clay, gravel and silt. A deposit that mixes coarse and fine grains like that can drain well in one spot and hold water a few feet away, depending on which layer a shovel hits.^[2]

For a patio or a planting bed, the safe approach is to treat whatever lies under the surface as unknown. Dig out soft or debris-filled material, pack what remains, and build up with clean Road Base so the finished surface does not depend on what an earlier crew left behind.^[1]

Old fill near the surface can hold brick, mortar and ash. Those bits do no harm under a base, but they make poor growing ground, so a bed dug into that kind of fill starts with fresh soil brought in rather than whatever comes out of the hole.^[1]

Wet Years, Light Snow and Two Freeze Dates

The NOAA station Phila Franklin Inst, PA, about 1 mile away, averages 50.7 inches of precipitation a year and 16.1 inches of snowfall. That is a lot of water for small spaces walled in by brick, so every surface needs a planned way out for it.^[3]

At that station the low reaches 32 F or colder on 62 days a year. The median last spring freeze is March 30, and the median first fall freeze comes on November 17. Repeated freezing and thawing loosens pavers set on a fine base, so an open, well drained layer under any hard surface pays off here.^[3]

Snow shoveled off a walk lands on the nearest bed or gravel strip and melts there over several days. A gravel strip of #57 Crushed Stone along a wall takes that melt and keeps it from soaking the masonry.^[3]

Spring planting and base work both wait for the ground to dry out after that March date, because packing wet soil leaves soft spots that sink later.^[3]

Courtyards and Roof Decks in ZIP 19102

The Census Bureau's survey counts 4,964 housing units in ZIP 19102. Detached single-family houses are 1 percent of them, compared with 8 percent across Philadelphia, a city of 748,270 units. The median year built in the ZIP is 1971, against 1949 for the city as a whole. Owners live in 20 percent of the ZIP's occupied homes.^[4]

Outdoor space in a ZIP of attached homes and apartment buildings comes in small pieces: a rear courtyard, a roof deck with planters, a strip of ground beside an entry, a shared garden. Small jobs still need the right material, and a single load of Garden Soil, Pea Gravel or Brown Shredded Mulch can finish several of them at once.^[4]

Roof decks add a rule of their own: watch the weight. Garden Soil weighs less than Topsoil for the same volume, so it suits deck planters, and a thin top of Brown Shredded Mulch adds little load while keeping the soil from drying in the wind.^[4]

Two Ways to Surface a Narrow Side Yard

A narrow yard between walls gets little sun and a lot of runoff, given the 50.7 inches of yearly precipitation at the nearby station. Two surfaces work well there, and they suit different uses.^[3]

Pea Gravel is the easy choice. It drains instantly, looks neat, and needs only edging and a thin packed base. The tradeoff is that round stones roll underfoot and drift onto pavers, so it suits a quiet garden corner more than a path to the trash bins.^[3]

Stone Dust Screenings is the firmer choice. Spread over Road Base and packed damp, it sets into a hard, flat surface that takes a wheelbarrow or a bicycle. It sheds water rather than soaking it up, so the surface needs a slight slope toward a drain or a strip of Drain Rock. With 62 freezing days a year at the station, keep that slope true so water never sits on it to freeze.^[3]

Edging matters for both surfaces. Steel or stone edging holds Pea Gravel in place, and a firm edge also keeps packed screenings from crumbling at the sides where feet and wheels land most often.^[3]

Soil and Mulch for Small Beds

Small beds in a courtyard or along an entry dry out at the edges and stay wet in the shade, so the soil mix matters more than the size of the bed. Topsoil blended with Compost loosens heavy ground and holds moisture without turning to mud. A new raised bed or a large planter takes Garden Soil straight from the load, and beds planted after the March 30 median last freeze settle in before the summer heat.^[3]

A finished bed looks best with a mulch top. Black Shredded Mulch gives a dark, clean contrast against brick, Brown Shredded Mulch blends in, and Red Mulch brightens a shady corner. Shredded mulch knits together and stays on a bed edge better than Wood Chips, which can float away in a downpour.^[3]

After the November 17 median first freeze, a fresh layer of mulch helps protect roots on the 62 days a year when the station drops to 32 F or colder.^[3]

Under a Patio Slab or a Paver Court

A paver court starts with digging to firm ground and laying fabric, since a deposit of sand, clay, gravel and silt can mix into the base if it is left bare. A lower course of #4 Crushed Stone or 1-1/2" Crushed Gravel drains fast, and Road Base packed in thin lifts gives the firm top layer. A screeded bed of Concrete Sand then sets the pavers.^[2]

A poured slab follows the same idea with fewer layers: a packed course of Road Base or Crushed Concrete, leveled and wetted before the pour. In both cases the slope should carry water toward the street or a drain line, never toward a neighbor's wall.^[3]

Stairwells down to a basement door collect water from the pavement above them. A floor drain set in Drain Rock or #57 Crushed Stone, wrapped in fabric, keeps that pit dry, and Concrete Sand under a few pavers at the foot of the stairs gives a firm, level footing.^[3]

The Pennsylvania Department of Transportation specifies Subbase, No. 2A aggregate, Section 350, in its Publication 408 Specifications. That section governs state roads. A homeowner or a small contractor building a courtyard can ask for the material by name and pack it well.^[5]