THE NATIONAL COASTAL POLLUTANT DISCHARGE INVENTORY Point Source Methods Document December 1993 Pollution Sources Characterization Branch Strategic Environmental Assessments Division Office of Ocean Resources Conservation and Assessment National Ocean Service National Oceanic and Atmospheric Administration Silver Spring, MD 20910 Project Team Percy A. Pacheco, Project Leader Anthony S. Pait- Methods document author Sheila J. Arenstam- Programming and analysis Alice E. DeSouza- GIS analysis and support Daniel R.G. Farrow - Technical review John J. Hayes -Methods document support Mitchell J. Katz- Editorial assistance Jamie Lowe - Methods document preparation Manyu Swain- Programming and analysis NCPDI Point Source Methods Document This document describes the methods used to develop the NCPDI Point Source Inventory, com­ pleted in December, 1993. Information within the inventory may change if more accurate or complete information is located. Subsequent versions of the national inventory may be released as improvements and refinements in data are incorporated into the inventory. Direct any comments, questions or problems relating to the NCPDI Point Source Inven­ tory to Percy A. Pacheco or Daniel R. G. Farrow at the address on the inside of the back cover. Page Section 1: Overview The Approach ......................................... ,.............................................................................................................. 1 Using the Inventory .............................................................................................................................................. 2 Using this Document............................................................................................................................................ 2 Section 2: Features of the Inventory Definition of Point Source.................................................................................................................................... 4 Base Year and Seasonal Estimates ....................................................................................................... :.............. 4 Study Area .......................... .................................................. ....... .................................. ................. ....................... 4 Pollutants in the Inventory.................................................................................................................................. 4 Additional Pollutant Discharge Information.................................................................................................... 6 Section 3: Estimating Discharges Data Sources .......................................................................................................................................................... 7 Data Input Files ..................................................................................................................................................... 7 Computational Procedures.................................................................................................................................. 11 Section 4: Data Accuracy & Sources of Error Accuracy of the Estimates .............................. ...................... ............................. ................................................... 17 Potential Sources of Error .................................................................................................................................... 18 Suggested Improvements .................................................................................................................................... 19 Appendices Ia. Point Source Data Dictionary...................................................................................................................... I-1 lb. Variable Name Cross Reference Table...................................................................................................... I-129 II. Typical Pollutant Concentrations for NCPDI Discharge Categories ................................................... II-1 III. Typical Flow Values .................................................................................................................................... III-1 IV. SAS Programs Used to Generate Point Source Pollutant Loading Estimates..................................... IV-1 V. Data Fields Included in the Seven Deliverable Files............................................................................... V-1" VI. Estuarine and Coastal Drainage Areas in the NCPDI ............................................................................ VI-1 VII. USGS Hydrologic Cataloging Units in the NCPDI ................................................................................. VII-1 VITI. Counties C:omprising fue NCPDI Study Area ......................................... ~ ....... ;...................................... - Vlll-1 --- ---- -- IX. Ust of Acronyms ....... :................................................................... ·························:····································· IX-1 Figures 1. NCPDI Study Area Showing Coastal Counties and Coastal Watershed Boundaries ....................... 5 2. Schematic for Estimating Point Source Discharges in the NCPDI ····························:·····················..... 8 Tables 1. Pollutants Included in the NCPDI ............................................................................................................. 6 2. Information Sources Used to Develop the NCPDI Point Source Inventory........................................ 9 3. General Equations Used to Estimate Loadings ....................................................................................... 14 i Section 1: Overview This document describes the data pollutant concentrations consid­ the estimates. To give the user sources and methods used to ered typical for the facility's this capability, the Project Team develop an inventory of direct­ industrial or municipal activity. has developed a variety of codes discharging point sources in the Typical pollutant concentration to document the data source(s), coastal watersheds of the Nation, data were an important source of the basis for each estimate, and as part of NOAA's National information used in making the cases where professional judg­ Coastal Pollutant Discharge discharge estimates. ment was used to modify or Inventory (NCPDI) (see insert). override data determined to be The inventory contains estimates The reliability and relative accu­ unacceptable. In addition, several of seasonal and annual pollutant racy of the discharge estimates supporting files have been devel­ loadings for 1991 for each active and the facility characterization oped that contain both the original pipe discharging pollutants to data depended on the availability, data received from the source and surface waters, along with loca­ quantity, and quality of informa­ that derived from key intermedi­ tion and operational characteris­ tion in the national data sources. ate steps in the estimation process. tics of the point source facilities in Because these data sources have This combination of source and the study area. A description of certain limitations, estimates often basis codes and supporting files the study area is included in required the use of assumptions provides an audit trail that can be Section 2. and typical values. used to independently calculate a loading estimate and assess its When possible, pollutant dis­ relative accuracy. charge estimates have been derived from monitoring sources. However, the amount of monitor­ ing data varied by pollutant There are five major steps in parameter. The greatest amount developing an inventory of direct­ of monitoring data was available discharging point sources and for the conventional pollutant estimating their discharge load­ parameters such as flow, total ings. These include: suspended solids (TSS), and biochemical oxygen demand • Identifying the primary data (BODS), with far less monitoring sources and obtaining the data available for heavy metals, . desired information in an nutrients, and oil and grease. appropriate format; Mosfmonitoring data were taken • Developing data input files, from the monthly Discharge including manipulating and Monitoring Reports (DMR) enhancing the primary data to completed as part of each facility's produce the Facility File, the National Pollutant Discharge Permit Data File, and the Elimination System (NPDES) Monitoring Data File; Compliance Monitoring Program. In some cases, monitoring data • Developing a data base of were taken from other data characteristics typical of differ­ sources, such as a facility's NPDES ent types of point sources. permit application. When moni­ These values are used when toring data were not available or facility-specific data are either appeared to be inaccurate, esti­ missing or unacceptable. These mates were made based on typical characteristics include NPDES permit limit requirements estimates for volume of flow when available. discharged, type and concentra­ It is important for users to under- . tion of pollutants discharged, If no monitoring, permit, or other stand the limitations of the data seasonal discharge patterns, and data were available or acceptable, and to be able to independently the percentage of process or estimates were made based on evaluate the relative accuracy of 1 sanitary versus cooling water or • Identification of potential the computational procedures. stormwater flow in