Stormwater management plan: Somerset County approval steps

It's the lowest-lying jurisdiction on Maryland's Eastern Shore, and most of its drainage pushes through tidal channels into Tangier Sound and the Pocomoke River. After a two-inch rain on saturated ground, that geography stops being a map and starts being a drainage failure. Standing water shuts down intersections along Route 13, backs up roadside ditches near Westover, and feeds nutrient-loaded runoff straight into the bay. Every acre of impervious cover a developer adds — a parking lot, a poultry house pad, a subdivision road — tilts the drainage network another notch toward failure. The Somerset County stormwater management plan approval process is the gate that decides whether that tilt gets caught or compounded.

The county doesn't run the program on its own. It answers to the Maryland Department of the Environment, the Chesapeake Bay Critical Area Commission, and the Somerset County Soil Conservation District. Three desks, three sets of standards, one engineer on the hook for making sure the drawings match what gets poured in the field. Here's how to navigate that stack without sending the project back to square one.

Regulatory framework: aligning local plans with Maryland standards

Three agencies, three sets of standards, one drainage plan. Cut any one leg and the submittal stalls.

The legal architecture rests on three legs. Take one out and the submission bounces.

The first leg is state law. Maryland's Stormwater Management Act of 2007 — built on the earlier 2000 framework — required every county to adopt a local program meeting or exceeding state standards. Somerset County codified this in the Stormwater Management Ordinance (Chapter 126 of the county code) and enforces the 2000 Maryland Stormwater Management and Sediment Control Manual with current revisions. The Manual mandates Environmental Site Design (ESD) as the first option on every project. ESD means using the site's natural features — sheet flow, vegetated buffers, micro-bioretention, rain gardens — before any structural BMP gets sized.

The second leg is the federal Clean Water Act, enforced through the National Pollutant Discharge Elimination System. Maryland runs its own delegated program. Somerset County is a non-municipal jurisdiction, so all stormwater discharges from its MS4 system are covered under a single county-wide permit. That permit binds the county — and by extension, any new development feeding the same drainage network — to the Chesapeake Bay Total Maximum Daily Load for nitrogen, phosphorus, and sediment. Exceed the approved loads and the bay's overall TMDL budget slides the wrong direction.

The third leg is the Chesapeake Bay Critical Area Act, which buffers tidal waters and the bay by 1,000 feet. Inside that zone, the Critical Area Commission layers on extra restrictions for impervious surface limits, forest cover, and BMP placement. Somerset County carries more Critical Area frontage than nearly any other Eastern Shore jurisdiction. Most projects trip all three layers at once.

A project that disturbs 5,000 square feet or more, or adds 5,000 square feet or more of impervious surface, triggers full state-level plan review. Smaller projects can use a simplified Standard Stormwater Management Plan through the county, but they still have to file. Don't assume residential scale means automatic exemption — every project hits the county desk.

Technical requirements for erosion and sediment control submissions

The Somerset County review desk doesn't grade plans on aesthetics. It grades them on whether the numbers add up in the field. Three documents drive the technical review: the erosion and sediment control (E/S) plan, the stormwater management (SWM) plan, and — where applicable — the Critical Area compliance package.

The E/S plan shows how the developer keeps soil on the site during construction. It starts with a grading plan and a written sequence — when to clear, when to stabilize, when to seed. Somerset County enforces the 2011 Maryland Standards and Specifications for Soil Erosion and Sediment Control, which set silt fence placement, stabilized construction entrances, and temporary sediment basin sizing. That basin sizing calculation is where most contractors trip. Required storage volume is 134 cubic yards per acre of disturbed area, or the volume derived from the 10-year, 24-hour storm, whichever is greater. Get that number wrong and the package bounces on the first technical review.

The SWM plan documents where the water goes after construction. ESD comes first. That means demonstrating the use of sheet flow, sheet flow to a vegetated area, micro-bioretention, and similar practices before any structural BMP is considered. Under COMAR 26.17.02, structural controls can only be evaluated after ESD has been optimized to the Maximum Extent Practicable (MEP). Once ESD can't deliver the required channel protection and water quality volume, the designer moves to a structural BMP — typically a bioretention facility, grass swale, or sand filter.

Required submittals for a complete technical package:

1. Existing and proposed drainage area maps at no smaller than 1" = 200' scale.

2. A geotechnical report with NRCS Web Soil Survey mapping and on-site soil borings wherever infiltration is proposed.

3. Hydrologic and hydraulic calculations (TR-55 is standard for rural Somerset sites) showing pre- and post-development peak flows for the 1-, 10-, and 100-year storm events.

4. An ESD feasibility narrative — a written explanation of why each practice was or wasn't used.

5. Structural BMP sizing and details, including a maintenance access easement and a recorded maintenance agreement.

6. A long-term inspection and maintenance schedule for every BMP on the site.

That last item gets ignored until the project is already under roof. The county treats the maintenance agreement as load-bearing — it runs with the land, not the owner. If a BMP fails an inspection five years out, the county holds the current owner accountable for the fix.

Navigating the Somerset County review and approval workflow

The county runs a phased stormwater management review process — linear on paper, but it crosses desks that don't share a calendar, and the order matters more than the form. Somerset County requires developers to submit plans through three formal phases administered by the Office of the County Engineer.

Step 1 — Pre-application meeting. Schedule this before any drawings get drafted. Bring a sketch plan, the NRCS Web Soil Survey output, and a rough drainage area. The county will flag which standards apply (Critical Area or not), the impervious surface cap, and known site issues — tidal wetlands, forest stands, FEMA floodplains. The meeting is free and saves months.

Step 2 — Concept phase. Submit the concept package covering overall site layout, drainage concepts, and intended ESD sequence. The county's contracted engineer does the first technical pass. Expect comments on drainage area splits, missed ESD opportunities, and missing soil data. This round usually takes 30 to 45 days.

Step 3 — Site development phase. With concept comments addressed, the site development package gets a second technical pass. ESD analysis tightens here. Anything that can be resolved with grading and landscape work — instead of structural BMPs — gets resolved here. The county also uses this phase to coordinate parallel reviews.

Step 4 — Critical Area Commission review. If the site sits inside the 1,000-foot buffer, the county forwards the package to the Critical Area Commission. Commission review can run 60 to 90 days and frequently requires habitat assessments, forest stand delineations, and buffer mitigation plans. Build that time into the schedule from day one.

Step 5 — Soil Conservation District sign-off. Most Somerset projects need Somerset County Soil Conservation District approval for the E/S portion. The District checks sediment control design against state standards and issues its own approval letter. Stormwater management approval runs parallel to this review — both have to clear before final endorsement.

Step 6 — Final construction phase. The final construction package goes in once concept and site development comments are resolved, ESD has been optimized to MEP under COMAR 26.17.02, and the District has signed off. The county confirms state-level General Permit coverage is in place before issuing final approval.

Step 7 — As-built certification. After construction, the design engineer certifies that installed infrastructure matches approved plans. Anything that wasn't on the approved plans — a relocated swale, a substituted outlet structure — is technically unauthorized until retroactively documented. As-builts get recorded with the Office of the County Engineer.

Standard residential or small commercial projects typically run four to six months. Anything inside the Critical Area, or above the 10-acre disturbance threshold, pushes past nine. Projects under 5,000 square feet of earth disturbance are generally exempt from full state SWM plan approval requirements but still file locally. Where things fall apart: skipping the pre-application meeting, or finding out about the Critical Area designation after the plans are half-drafted.

Environmental constraints in coastal development zones

Most of Somerset sits under five feet of elevation. The drainage network wasn't built for the next thirty years of tide. Pretend otherwise and the BMP becomes a deferred maintenance liability.

Somerset County's waterfront isn't a perk. It's a load-bearing constraint that determines whether the project gets built.

The Critical Area 100-foot buffer is the first line. No new impervious surface, no new structures, no clearing of forest or vegetation inside that buffer. The buffer is measured landward from the mean high water line of tidal waters, or the edge of adjacent tidal wetlands. If the lot has any tidal shoreline, that line goes on the plan first and the rest of the site gets drawn around it.

Behind the buffer sits the 1,000-foot expanded buffer, where the Critical Area Commission's 10% impervious rule applies. Inside that expanded area, a grandfathered lot can be developed, but the impervious cap is the lesser of 10% of the lot area or 25% of the existing impervious surface. Once that threshold is exceeded, every additional square foot of impervious surface requires mitigation — typically forest creation or a fee-in-lieu payment into the Critical Area fund.

Tidal and nontidal wetlands sit in a separate regulatory layer. MDE's Wetlands and Waterways Program regulates any work below mean high water or in wetlands adjacent to tidal waters. A project that dredges, fills, or alters a wetland needs joint state and federal permits — a Maryland Tidal Wetlands License plus a Section 404 permit from the U.S. Army Corps of Engineers. That permit timeline runs six months to a year minimum, and the application has to be in long before the SWM plan is finalized.

Sea level rise is the variable that doesn't fit on a standard site plan. NOAA's intermediate projections put the Eastern Shore at roughly 1.3 to 1.6 feet of additional rise by 2050. For a county where most of the land sits under five feet and the highest point is around 18, that isn't a future concern — it's a present-day grading problem. Freeboard on any structural BMP, tail water elevation on any outlet structure, and the finished floor elevation on any building all need to account for the next 30 years of tide, not the last one.

Somerset County reviewers now ask how the design handles a 2050-condition 10-year storm under a 2050 tide. "We'll deal with it later" is a rejection, not an answer.

Common compliance pitfalls during the permitting lifecycle

Most projects don't fail at the design desk. They fail two years after the last ribbon is cut, when the BMP clogs and nobody on the deed knows whose problem it is.

Five pitfalls account for the majority of failed inspections, resubmissions, and enforcement actions in Somerset County.

1. Missing the Critical Area in deed research. Buyers close on a lot, the surveyor flags tidal wetlands six months later, and the plans get redrawn from scratch. Pull the plat, check the Critical Area map, and walk the shoreline before any work starts. If the property falls inside the 1,000-foot buffer, the Critical Area Commission owns the timeline.

2. Underestimating soil conductivity. Infiltration-based ESD looks cheap on paper until the soil boring comes back with a hydraulic conductivity that won't support it. When that happens, the design has to pivot to a structural BMP — usually a bioretention facility with an underdrain — and the redesign adds 60 to 90 days. Order the geotech work in the concept phase, not after the site development comments come back.

3. Treating ESD as a checkbox. ESD to MEP is not a line item. It's a sequence of design decisions — sheet flow first, vegetated conveyance second, micro-bioretention third — before structural controls get considered. Skipping that sequence and going straight to a sand filter triggers a comment letter under COMAR 26.17.02 and a resubmission cycle.

4. No maintenance plan, no recording. The maintenance agreement runs with the land, but only if it gets recorded against the deed. Engineers who draft BMP details but skip the maintenance schedule end up re-issuing the package. Worse, owners who never see the recorded agreement find out about their obligations the hard way — when the BMP fails an inspection and the county sends the bill to whoever currently holds title.

5. Forgetting the as-built certification. As-built certifications are mandatory upon project completion to verify that installed infrastructure strictly conforms to county-approved engineering plans. The county doesn't accept "we changed it in the field" without a formal as-built revision.

A sixth pitfall sits outside the technical review but bleeds into every project that hits it: budget overruns triggered by review delays. Every month a project sits in comment-response adds carrying costs. The efficient path — pre-application meeting, complete concept package, soil data in hand, ESD optimized before any structural BMP — runs four to six months for a typical small residential project. Anything that misses that window usually doubles the engineering and review fees.

Final position

The Somerset County stormwater management approval process isn't bureaucracy for its own sake. It's the only mechanism standing between a low-lying coastal county and a drainage network that already runs over capacity on a two-inch rain. The system works — three agencies, phased submittals, ESD to MEP, mandatory as-builts — when each leg is treated as load-bearing. Cut one and the project either stalls or it gets built wrong, and the wrong version of a stormwater plan in Somerset County doesn't show up on the inspection report. It shows up the next time the tide doesn't drain.

Pull the soils in the concept phase. Run the Critical Area overlay before the survey. Treat ESD as a real design sequence, not a checkbox. Submit a complete maintenance agreement with the deed. Certify the as-builts before the contractor leaves the site. The county's review desk isn't slow on purpose — it's thorough because the ground in Somerset County doesn't forgive deferred maintenance, and the bay downstream pays for every shortcut.