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diff --git a/docs/conf.py b/docs/conf.py
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--- a/docs/conf.py
+++ b/docs/conf.py
@@ -96,6 +96,10 @@
 #
 html_favicon = "_static/favicon.ico"
 
+# intersphinx mapping to idaes
+intersphinx_mapping = {
+    "idaes": ("https://idaes-pse.readthedocs.io/en/stable/", None),
+}
 
 rst_epilog = """
 .. |Binder launch button| image:: https://mybinder.org/badge_logo.svg
diff --git a/docs/technical_reference/flowsheets/gac.rst b/docs/technical_reference/flowsheets/gac.rst
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+Granular Activated Carbon
+=========================
+
+Introduction
+------------
+
+The simple granular activated carbon (GAC) flowsheet can be simulated to predict the performance of a GAC system to treat residual organics. This flowsheet can
+be useful to expedite the set-up, usage, and costing of a GAC system for conventional water treatment applications using the constant pattern homogeneous
+surface diffusion model (CPHSDM) model.
+
+Implementation
+--------------
+
+Only consisting of a single unit operation, the assumptions for the flowsheet are aligned with those detailed in the :doc:`GAC unit model documentation </technical_reference/unit_models/gac>`.
+The code-based naming of modeling objects for the inlets, outlets, units, and streams are shown in Figure 1.
+
+.. figure:: ../../_static/flowsheets/gac.png
+    :width: 500
+    :align: center
+
+    Figure 1. GAC flowsheet
+
+The following modeling components are used within the flowsheet:
+
+Documentation for property models:
+    * :doc:`/technical_reference/property_models/mc_aq_sol`
+Documentation for unit models:
+    * :doc:`/technical_reference/unit_models/gac`
+Documentation for unit models from IDAES:
+    * :doc:`idaes:reference_guides/model_libraries/generic/unit_models/feed`
+    * :doc:`idaes:reference_guides/model_libraries/generic/unit_models/product`
+Documentation for costing models:
+    * :doc:`/technical_reference/costing/watertap_costing`
+    * :doc:`/technical_reference/costing/gac`
+
+Degrees of Freedom
+------------------
+
+The degrees of freedom for the flowsheet can change depending on the configuration options specified during the build. Excluding those variables which are
+only necessary for specific configuration options, the following variables are initially fixed for simulating the GAC flowsheet (i.e., degrees of freedom = 0):
+
+    * feed conditions (component flows, temperature, pressure)
+    * Freundlich isotherm parameters :math:`k` and :math:`\frac{1}{n}`
+    * liquid phase film transfer coefficient
+    * surface diffusion coefficient
+    * particle apparent density
+    * particle diameter
+    * empty bed contact time
+    * bed voidage
+    * bed length
+    * effluent to inlet concentration ratio at operational time
+    * CPHSDM empirical parameters
+
+Flowsheet Specifications
+------------------------
+
+.. csv-table::
+   :header: "Description", "Value", "Units"
+
+   "feed molar flowrate of water", "2433.81215", ":math:`\text{mol}/\text{s}`"
+   "feed molar flowrate of the solute", "0.05476625", ":math:`\text{mol}/\text{s}`"
+   "feed temperature", "298.15", ":math:`\text{K}`"
+   "feed pressure", "101325", ":math:`\text{Pa}`"
+   "Freundlich isotherm k parameter", "10", ":math:`\left(\text{m}^3\text{/kg}\right)^\left( \frac{1}{n} \right)`"
+   "Freundlich isotherm 1/n parameter", "0.9", ":math:`\text{dimensionless}`"
+   "liquid phase film transfer coefficient", "5e-5", ":math:`\text{m/s}`"
+   "surface diffusion coefficient", "2e-13", ":math:`\text{m}^2\text{/s}`"
+   "gac apparent density", "750", ":math:`\text{kg/}\text{m}^3`"
+   "gac particle diameter", "0.001", ":math:`\text{m}`"
+   "empty bed contact time", "600", ":math:`\text{s}`"
+   "bed void fraction", "0.4", ":math:`\text{dimensionless}`"
+   "bed length", "6", ":math:`\text{m}`"
+   "effluent to inlet concentration ratio at operational time", "0.50", ":math:`\text{dimensionless}`"
+   "Stanton equation parameter 0", "3.68421", ":math:`\text{dimensionless}`"
+   "Stanton equation parameter 1", "13.1579", ":math:`\text{dimensionless}`"
+   "throughput equation parameter 0", "0.784576", ":math:`\text{dimensionless}`"
+   "throughput equation parameter 1", "0.239663", ":math:`\text{dimensionless}`"
+   "throughput equation parameter 2", "0.484422", ":math:`\text{dimensionless}`"
+   "throughput equation parameter 3", "0.003206", ":math:`\text{dimensionless}`"
+   "throughput equation parameter 4", "0.134987", ":math:`\text{dimensionless}`"
+
+Future Refinements
+------------------
+
+The following modifications to the GAC flowsheet are planned for development:
+
+    * Add surrogate models to lessen the need for numerous empirical parameters
+    * Improve auto-scaling of model for ease of use
+
+Code Documentation
+------------------
+
+* :mod:`watertap.examples.flowsheets.gac`
+
+References
+----------
+Hand, D. W., Crittenden, J. C., & Thacker, W. E. (1984). Simplified models for design of fixed-bed adsorption systems.
+Journal of Environmental Engineering, 110(2), 440-456.
+
+Crittenden, J., Rhodes, R., Hand, D., Howe, K., & Tchobanoglous, G. (2012). MWHs Water Treatment. Principles and Design.
+John Wiley & Sons.
+
+United States Environmental Protection Agency. (2021). Work Breakdown Structure-Based Cost Model for Granular Activated
+Carbon Drinking Water Treatment.
\ No newline at end of file
diff --git a/docs/technical_reference/flowsheets/index.rst b/docs/technical_reference/flowsheets/index.rst
index 84beed6bfa..c0b8b04a0c 100644
--- a/docs/technical_reference/flowsheets/index.rst
+++ b/docs/technical_reference/flowsheets/index.rst
@@ -13,3 +13,4 @@ Flowsheets
    electrodialysis_1stack_conc_recirc
    electrodialysis_1stack
    crystallization
+   gac