Civil Engineering & Site Design
Street, storm drain, sewer and site plans drawn to your agency's standards, so conditions of approval become plans a contractor can build.
An improvement plan is a set of construction drawings, signed and sealed by a licensed civil engineer, showing how streets, curbs, storm drains, sewer and water mains and related infrastructure will be built to a public agency's standards.
Often called civil or public improvement plans, they are reviewed by the city engineer or county public works department, then used to set bonds, issue permits and inspect the work.
Building plans cover the structure; improvement plans connect it to the street and utilities. Pads and slopes usually go on a separate grading plan, though some agencies combine the two.
Deliverables
Scope follows the agency's checklist. A typical submittal includes:
Title sheet, plan-and-profile and detail sheets, signed and sealed by a California civil engineer.
Hydrology, hydraulic, pipe sizing and sewer capacity calculations, as the reviewing agency requires.
Quantities and unit costs the agency typically uses to set improvement security and fees.
Responses to agency comments, resubmittals, and record drawings after construction where required.
Most improvement plans answer a condition of approval. Common triggers:
Map conditions often require new streets, drainage and utilities. See parcel and subdivision maps.
The building permit needs onsite utilities, paving and fire access, plus any offsite work. See site layout.
The city or county requires curb, gutter, sidewalk or a driveway approach along the street.
A lot needs a public main extended to reach service or an outlet.
Process
Five steps from conditions to acceptance.
We gather the conditions of approval, agency standards, a topographic survey with boundary data, utility records and any soils report.
Streets, sewers, water mains and storm drains are laid out in plan and profile; storm drains are sized with stormwater calculations.
Signed plans, calculations, the engineer's estimate and fees go to the agency; plans are revised until approved.
The owner signs any improvement agreement and posts security. Encroachment and other permits follow, often issued to the contractor.
Improvements are set out by construction staking from the approved plans; we answer field questions and prepare record drawings.
Most projects combine several.
Subdivision improvement plans design the streets, storm drains, sewer and water mains and street lights that tentative map conditions require.
Apartment complex site improvements cover drive aisles, parking, fire access, onsite utilities and accessible routes, plus any public frontage work.
Street frontage improvements build or replace the curb, gutter, sidewalk, driveway approach and pavement along a property's street edge.
Storm drain improvement plans lay out inlets, pipes, manholes, outfalls and detention or treatment facilities, sized for the design storm in the local drainage manual.
A sanitary sewer main extension carries a public sewer from the nearest existing main to a new lot or subdivision, built to the sewer agency's standards.
California rules
The rules that matter most:
Under the Subdivision Map Act, each city and county regulates the design and improvement of subdivisions by ordinance (§66411). "Design" includes street grades and widths, drainage and sanitary facilities (§66418). So standard plans, sheet formats and checklists differ by agency.
Civil engineering plans must be prepared by, or under the responsible charge of, a licensed civil engineer, who signs, seals and dates each construction sheet. Interim sets are marked with their purpose, such as "for plan check only" (§6735).
If public improvements are unfinished when a final map is approved, the subdivider must sign an improvement agreement backed by security (§66462). Performance and labor-and-materials security are each set by the agency at 50 to 100 percent of the estimated cost, plus a one-year warranty amount (§66499.3).
Any work, driveway or utility in a state highway right-of-way needs a Caltrans encroachment permit (Streets and Highways Code §670). City streets and county roads need that agency's encroachment or street-work permit; names and requirements vary.
Requirements vary by city, county and district; sewer, water and fire agencies may review separately.
Last reviewed .
A set of improvement plans typically includes a title sheet with general notes, plan-and-profile sheets for streets, storm drains and sewer mains, construction details, and striping or street lighting sheets where required. Calculations and an engineer's estimate usually accompany the plans. The reviewing agency's checklist sets the exact sheet list.
Improvement plans in California must be prepared by, or under the responsible charge of, a licensed civil engineer, who signs and seals every sheet released for construction (Business and Professions Code §6735). A land surveyor supplies the survey and staking, but land surveying does not include designing civil engineering works (§8728).
Improvement plans show the streets, storm drains, sewer and water mains and other infrastructure a project builds, often in the public right-of-way. A grading plan shows how the ground itself is reshaped, with existing and finished contours, pads, slopes and earthwork. Many projects need both, designed together so pad, curb and pipe elevations match.
The cost and schedule of improvement plans depend on the improvements required, site slope and drainage, the distance to existing sewer and storm drain connections, the agency's standards and plan check cycles, and whether a sewer district, water purveyor or Caltrans must also approve. Share the conditions of approval, site plan and any survey; the proposal then sets scope and timing.